WorldWideScience

Sample records for epr-g-ma toughened polyamide

  1. Taguchi analysis of extrusion variables and composition effects on the morphology and mechanical properties of EPR-g-MA toughened polyamide 6 and its composite with short glass fiber

    International Nuclear Information System (INIS)

    Shojaei, A.; Fereydoon, M.

    2009-01-01

    Various compositions of maleated ethylene-propylene-rubber (EPR-g-MA) toughened polyamide 6 without and with short glass fiber, i.e. 5-20 wt.% rubber and 5-20 wt.% fiber, are prepared using an industrial twin-screw extruder at different levels of feed rate (100-250 kg/h), screw speed (200-450 rpm) and barrel temperature (230-260 deg. C). Trial runs designed based on the Taguchi's orthogonal arrays are subjected to tensile, impact, scanning electron microscopy (SEM) and optical microscopy tests; and the results are used to perform the analysis of variance (ANOVA). It is shown that the rubber particle size decreases significantly by increasing the rubber content for the unreinforced blend. The results also indicate that the composition of the compounds is the most influential factor on the phase morphology and mechanical properties of both the unreinforced and reinforced blends compared to the extrusion variables. But the processing parameters can also influence the performance characteristics slightly. The most important processing parameter, among the others, is shown to be the mixing temperature, which decreases the fiber length greatly and leads to the thermo-mechanical degradation of the polymers above 240 deg. C

  2. Dynamic mechanical properties of toughened polyamide composites

    International Nuclear Information System (INIS)

    Alsewailem, Fares D.

    2008-01-01

    The effect of incorporating thermoplastic rubber on the dynamic mechanical properties, storage and loss moduli, of virgin and recycled glass-fiber-reinforced polyamide 66 has been investigated in this study. Styrene-Ethylene-Styrene and Ethylene-Propylene grafted with maleic anhydride were used as elastomers for toughening. Dynamic mechanical properties of the composites were examined by the rotational rhometry. Shear storage and loss moduli of recycled and virgin materials were measured against frequency. Also the variation of storage modulus of the virgin composites was measured against temperatures by conducting a series of torsion tests. Both dynamic storage and loss moduli of the composites were found to increase with increasing glass fiber and rubber contents. Recycled composites had lower values of dynamic modulus compared that of virgin composites; however by proper combining of fiber and rubber into the recycled material, its modulus fairly matches that of the virgin material. Addition of rubber to virgin composites causes a reduction in G' as temperature increases. Rubber, which acts as a stress concentrator, had a major effect on minimizing the overall modulus of the composites. The in G' versus temperature has been observed for all composites: however the temperature at which the transition G' occurs decreases with increasing rubber content. (author)

  3. Experimental comparison of manufacturing techniques of toughened and nanoreinforced polyamides

    Science.gov (United States)

    Siengchin, S.; Bergmann, C.; Dangtungee, R.

    2011-11-01

    Composites consisting of polyamide-6 (PA-6), nitrile rubber (NBR), and sodium fluorohectorite (FH) or alumina silicate (Sungloss; SG) were produced by different techniques with latex precompounding. Their tensile and thermomechanical properties were determined by using tensile tests and a dynamic-mechanical analysis, performed at various temperatures. The PA-6/NBR composite systems produced by the direct melt compounding outperformed those obtained by using the masterbatch technique with respect to the strength and ductility, but the latter ones had a higher storage modulus.

  4. Toughened nanocomposites of polyamide-6 and polyepichlorohydrin elastomer: mechanical and morphological properties

    International Nuclear Information System (INIS)

    Pinotti, Caio A.; Goncalves, Maria C.; Felisberti, Maria I.

    2009-01-01

    Blends of polyamide 6, P A6, and polyepichlorohydrin elastomer, PE Pi, nano composites of P A6 and OMMT and toughened nano composites, P A6/PE Pi/OMMT were prepared by twin-screw extrusion. Nanocomposites of P A6 and organophilic clay presented morphology of exfoliated clay with the presence of some tactoids, which were investigated by XRD and TEM. The blends P A6/PE Pi are immiscible with morphology of elastomer disperse phase. The size of the elastomer phase in the PA6 matrix and a better distribution of these phase were achieved with the incorporation of the clay in the ternary nanocomposites. Toughened nano composites presented increases in Young's modulus, Izod impact strength and yield stress, comparing with the blends of P A6 and polyepichlorohydrin elastomer. (author)

  5. Polyamide 4,6 nanocomposites with and without the use of a maleated polyolefin elastomer as a toughener

    International Nuclear Information System (INIS)

    Chiu, Fang-Chyou; Deng, Tsung-Lin

    2011-01-01

    In this study, polyamide 4,6 (PA 4,6)-based nanocomposites were successfully prepared using a twin screw extruder. A commercial organo-montmorillonite (denoted as 30B) and a commercial maleated polyolefin elastomer (denoted as POEMA) served as the reinforcing filler and toughener, respectively. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results confirmed the nano-scaled dispersion of 30B in the composites. Nevertheless, the presence of POEMA slightly depreciated the dispersibility of 30B. Polarized light microscope (PLM) observations showed that the inclusions of 30B and POEMA led to the formation of diffused/broken PA 4,6 spherulites. Differential scanning calorimetry (DSC) results indicated that the addition of 30B retarded the crystallization of PA 4,6; the addition of POEMA led to a similar retardation effect on PA 4,6 crystallization. Interesting melting behaviors associated mainly with the crystal annealing of PA 4,6 upon heating were observed for the fast-cooled samples. The presence of POEMA was noted to hamper the annealing process of PA 4,6 crystals. The thermal stability enhancement of PA 4,6 in the presence of 30B was further raised to a higher extent when POEMA was included in the matrix. The rigidity, including the storage/Young's/flexural moduli, of PA 4,6 significantly increased after adding 30B. These properties, however, declined after the additional incorporation of POEMA. The PA 4,6/POEMA/30B nanocomposites basically displayed balanced impact strength between those of the neat PA 4,6 and PA 4,6/POEMA blends.

  6. Toughening of poly(lactic acid without sacrificing stiffness and strength by melt-blending with polyamide 11 and selective localization of halloysite nanotubes

    Directory of Open Access Journals (Sweden)

    B. J. Rashmi

    2015-08-01

    Full Text Available This paper aims at improving the mechanical behavior of biobased brittle amorphous polylactide (PLA by extrusion melt-blending with biobased semi-crystalline polyamide 11 (PA11 and addition of halloysite nanotubes (HNT. The morphological analysis of the PLA/PA11/HNT blends shows a strong interface between the two polymeric phases due to hydrogen bonding, and the migration of HNTs towards PA11 phase inducing their selective localization in one of the polymeric phases of the blend. A ‘salami-like’ structure is formed revealing a HNTs-rich tubular-like (fibrillar PA11 phase. Moreover, HNTs localized in the dispersed phase act as nucleating agents for PA11. Compared to neat PLA, this leads to a remarkable improvement in tensile and impact properties (elongation at break is multiplied by a factor 43, impact strength by 2, whereas tensile strength and stiffness are almost unchanged. The toughening mechanism is discussed based on the combined effect of resistance to crack propagation and nanotubes load bearing capacity due to the existence of the fibrillar structure. Thus, blending brittle PLA with PA11 and HNT nanotubes results in tailor-made PLA-based compounds with enhanced ductility without sacrificing stiffness and strength.

  7. Toughening of Zirconia composites

    International Nuclear Information System (INIS)

    Burlingame, N.H.

    1980-06-01

    The addition of a ZrO 2 dispersion can significantly enhance the toughness of a ceramic matrix material. The toughness improvement is due to a stress reduction at the tip of a propagating crack which is the result of a preferential martensitic transformation of ZrO 2 particles in the stress field of the crack. From thermodynamic considerations and experimental observations the toughening effect is show to be strongly dependent on the ZrO 2 particle size. The effect of variations in temperature, composition and matrix materials are demonstrated, and analyzed in respect to the resultant deviations in the particle size toughening effect

  8. Effects of Electron Beam Irradiation on Binary Polyamide-6 Blends with Metallocene Copolymers

    International Nuclear Information System (INIS)

    Rosales, C.

    2006-01-01

    A versatile way to produce new materials with high Izod impact strength and reduced heat deformations is the irradiation of compatibilized blends. The effect of electron beam irradiation and different types of dispersed phase grafted copolymers on thermal and mechanical properties, and SEM morphology of polyamide-6 (PA-6) blends were investigated. Two metallocene copolymers (mEPDM and mPOE) grafted in-situ with maleic anhydride and two commercial maleated copolymers (EPDM-g-MA and mEPR-g-MA) were employed in binary blends with PA6 as matrix. The blends were prepared by extrusion with a composition of 80 wt. % of PA-6. The influence of the radical or functional groups generated in the grafting and the irradiation processes (25, 50, 100 and 200 kGy) was found by ATR-FTIR. The blends exhibited the characteristic thermal behavior of immiscible systems. All compatibilizers employed influenced the melting and crystallization behavior of the blend components without irradiation and an improvement in interface adhesion was clearly observed by SEM micrographs. The sizes of the dispersed phase in the non-irradiated reactive blends were in agreement with the viscosity ratios of the blend components. High toughness materials were obtained with ethylene-polypropylene-diene (mEPDM) grafted copolymers without significant variations in their thermal properties and Izod impact strength at room temperature and -30 degree with the irradiation doses. However, the toughness of the blends with grafted metallocene polyethylenes was affected by the irradiation doses employed. Therefore, the gel content and tensile properties of the samples depended on the chain scission, crosslinking and/or grafting reactions of the blend components

  9. Wear mechanisms of toughened zirconias

    International Nuclear Information System (INIS)

    Becker, P.C.; Libsch, T.A.; Rhee, S.K.

    1985-01-01

    The dry friction and wear behavior of toughened zirconias against hardened steel was studied using the falex ring and block technique. Three experimental ZrO 2 -Y 2 O 3 ceramics and two commerical ZrO 2 -MgO ceramics were investigated. Each ceramic was tested at 500 and 2000 rpm at normal loads in the range 2.3 to 40.8 kg. Significant trends in the friction and wear data were found correlating composition, test speeds, and loads. Microstructural examination of the ring, ceramic block, and wear debris has shown that the wear process is very complex and incorporates a number of mechanisms

  10. Stabilization of modified polyamide matrix

    International Nuclear Information System (INIS)

    Marchini, Leonardo G.; Parra, Duclerc F.; Lugao, Ademar B.

    2011-01-01

    Films of PA 6 (polyamide) doped with europium luminescent complexes have been develop and studied for applications in advanced technologies. Development of optical marker for process monitoring is the focus of the present study. Based in doped luminescent polyamide samples were prepared for polymer processing use. Films were prepared by dissolution of PA 6 in acid moiety with addition of europium complex. Stability evaluation was done in samples submitted to irradiation with 10 and 100 kGy of ionizing source. The luminescent polymer matrices were characterized using the techniques of infrared, thermogravimetry, differential scanning calorimetry and photoluminescent properties by electron emission spectroscopy. (author)

  11. Stabilization of modified polyamide matrix

    Energy Technology Data Exchange (ETDEWEB)

    Marchini, Leonardo G.; Parra, Duclerc F.; Lugao, Ademar B., E-mail: dfparra@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Films of PA 6 (polyamide) doped with europium luminescent complexes have been develop and studied for applications in advanced technologies. Development of optical marker for process monitoring is the focus of the present study. Based in doped luminescent polyamide samples were prepared for polymer processing use. Films were prepared by dissolution of PA 6 in acid moiety with addition of europium complex. Stability evaluation was done in samples submitted to irradiation with 10 and 100 kGy of ionizing source. The luminescent polymer matrices were characterized using the techniques of infrared, thermogravimetry, differential scanning calorimetry and photoluminescent properties by electron emission spectroscopy. (author)

  12. Toughening Mechanisms in Nanolayered MAX Phase Ceramics—A Review

    Directory of Open Access Journals (Sweden)

    Xinhua Chen

    2017-03-01

    Full Text Available Advanced engineering and functional ceramics are sensitive to damage cracks, which delay the wide applications of these materials in various fields. Ceramic composites with enhanced fracture toughness may trigger a paradigm for design and application of the brittle components. This paper reviews the toughening mechanisms for the nanolayered MAX phase ceramics. The main toughening mechanisms for these ternary compounds were controlled by particle toughening, phase-transformation toughening and fiber-reinforced toughening, as well as texture toughening. Based on the various toughening mechanisms in MAX phase, models of SiC particles and fibers toughening Ti3SiC2 are established to predict and explain the toughening mechanisms. The modeling work provides insights and guidance to fabricate MAX phase-related composites with optimized microstructures in order to achieve the desired mechanical properties required for harsh application environments.

  13. Rigid particle toughening of aliphatic polyketone

    NARCIS (Netherlands)

    Zuiderduin, W.C.J.; Huetink, Han; Gaymans, R.J.

    2006-01-01

    The influence of precipitated calcium carbonate particles on the toughening behaviour of aliphatic polyketone has been studied. The calcium carbonate particles had a particle size of 0.7 mm and a stearic acid coating (1%). Composites of 0e31.5 vol% CaCO3 content have been compounded and injection

  14. Toughening and creep in multiphase intermetallics through ...

    Indian Academy of Sciences (India)

    It has however often been the case that the process of ductilisation or toughening has also led to a decrease in high temperature properties, especially creep. In this paper we describe approaches to the ductilisation of two different classes of intermetallic alloys through alloying to introduce beneficial, second phase effects.

  15. Interlayer toughening of fiber composite flywheel rotors

    Science.gov (United States)

    Groves, Scott E.; Deteresa, Steven J.

    1998-01-01

    An interlayer toughening mechanism to mitigate the growth of damage in fiber composite flywheel rotors for long application. The interlayer toughening mechanism may comprise one or more tough layers composed of high-elongation fibers, high-strength fibers arranged in a woven pattern at a range from 0.degree. to 90.degree. to the rotor axis and bound by a ductile matrix material which adheres to and is compatible with the materials used for the bulk of the rotor. The number and spacing of the tough interlayers is a function of the design requirements and expected lifetime of the rotor. The mechanism has particular application in uninterruptable power supplies, electrical power grid reservoirs, and compulsators for electric guns, as well as electromechanical batteries for vehicles.

  16. Grinding mechanism of zirconia toughened alumina

    International Nuclear Information System (INIS)

    Tsukuda, A.; Kondo, Y.; Yokota, K.

    1998-01-01

    In the grinding process, physical properties of ceramics affect both grinding mechanism and quality of ground surface. In this study we focused on fracture toughness of ceramics and the effect on grinding. A grinding test was carried out by single point grinding for ten different zirconia toughened alumina ceramics with different monoclinic zirconia contents. Effects of zirconia contents on the grinding mechanism and crack initiation were discussed. Copyright (1998) AD-TECH - International Foundation for the Advancement of Technology Ltd

  17. Polyamide copolymers having 2,5-furan dicarboxamide units

    Science.gov (United States)

    Chisholm, Bret Ja; Samanta, Satyabrata

    2017-09-19

    Polyamide copolymers, and methods of making and using polyamide copolymers, having 2,5-furan dicarboxamide units are disclosed herein. Such polymers can be useful for engineering thermoplastics having advantageous physical and/or chemical properties.

  18. High temperature strengthening of zirconium-toughened ceramics

    International Nuclear Information System (INIS)

    Claussen, N.

    1986-01-01

    Transformation-toughened (i.e. ZrO/sub 2/-toughened) ceramics represent a new class of high performance ceramics with spectacular strength properties at low and intermediate temperatures. However, at temperatures above about 700 0 C, most of these tough oxide-base ceramics can no longer be used as load-bearing engineering parts because of characteristic deficiencies. The aim of the present paper is to provide and discuss microstructural design strategies which may enable ZrO/sub 2/-toughened ceramics to be applied at higher temperatures. From the various strategies suggested, three appear to show good prospects, namely (a) the prevention of glassy intergranular films, (b) the addition of hard high modulus particles and (c) whikser or fibre reinforcement. Experimental approaches are presented from some ZrO/sub 2/-toughened ceramics, elg. tetragonal ZrO/sub 2/ polycrystals and ZrO/sub 2/-toughened cordierite, spinel and mullite

  19. Glass ceramic toughened with tetragonal zirconia

    Science.gov (United States)

    Keefer, Keith D.; Michalske, Terry A.

    1986-01-01

    A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat-treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nucleating agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200.degree. to 1700.degree. C. and is then heat-treated at a temperature within the range of 800.degree. to 1200.degree. C. in order to precipitate tetragonal ZrO.sub.2. The composition, as well as the length and temperature of the heat-treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

  20. Zirconia toughened ceramics for heat engine applications

    International Nuclear Information System (INIS)

    Rossi, G.A.; Blum, J.B.; Manwiller, K.E.; Knapp, C.E.

    1986-01-01

    Three classes of zirconia toughened ceramics (ZTC) were studied, i.e. Mg-PSZ (MgO-partially stabilized zirconia), Y-TZP (Y/sub 2/O/sub 3/-tetragonal zirconia polycrystals) and ZTA (zirconia toughened alumina). The main objective was to improve the high temperature strength and toughness, which are not satisfactory in the ''state of the art'' ZTC materials. Powders prepared by melting/rapid solidification and by chemical routes were used. The green parts were made by both dry and wet shape forming methods. Fine grained Mg-PSZ ceramics with unique microstructures were produced using the rapidly solidified powders. The Y-TZP materials were improved mainly through microstructure control and by addition of alpha alumina as a dispersed phase. Preliminary results on ZTA ceramics made with the rapidly solidified powders were also obtained. It is concluded that the Al/sub 2/O/sub 3//Y-TZP composites offer a good chance of meeting the program objectives

  1. Interlaminar Toughening of Fiber Reinforced Polymers

    Science.gov (United States)

    Bian, Dakai

    Modification in the resin-rich region between plies, also known as the interlaminar region, was investigated to increase the toughness of laminate composites structures. To achieve suitable modifications, the complexities of the physical and chemical processes during the resin curing procedure must be studied. This includes analyses of the interactions among the co-dependent microstructure, process parameters, and material responses. This dissertation seeks to investigate these interactions via a series of experimental and numerical analyses of the geometric- and temperature-based effects on locally interleaving toughening methods and further interlaminar synergistic toughening without interleaf. Two major weaknesses in composite materials are the brittle resin-rich interlaminar region which forms between the fiber plies after resin infusion, and the ply dropoff region which introduces stress concentration under loads. To address these weaknesses and increase the delamination resistance of the composite specimens, a dual bonding process was explored to alleviate the dropoff effect and toughen the interlaminar region. Hot melt bonding was investigated by applying clamping pressure to ductile thermoplastic interleaf and fiber fabric at an elevated temperature, while diffusion bonding between thermoplastic interleaf and thermoset resin is performed during the resin infusion. This method increased the fracture energy level and thus delamination resistance in the interlaminar region because of deep interleaf penetration into fiber bundles which helped confining crack propagation in the toughened area. The diffusion and precipitation between thermosets and thermoplastics also improved the delamination resistance by forming a semi-interpenetration networks. This phenomenon was investigated in concoctions of low-concentration polystyrene additive modified epoxy system, which facilitates diffusion and precipitation without increasing the viscosity of the system

  2. Evaluation of advanced transformation toughened zirconia

    International Nuclear Information System (INIS)

    Swab, J.J.

    1986-01-01

    Transformation toughened zirconia (TTZ) is a material being considered for use in advanced heat engines. However, at elevated temperatures TTZ materials undergo a phase transformation from tetragonal to the monoclinic with an associated volume increase of approximately 5%. This transformation results in a loss of strength and fracture toughness. Six commercially available Japanese TTZ materials and one experimental domestic grade were examined for the extent and effect of this phase transformation after exposure to elevated temperatures (1000 to 1200 0 C) for times of 100 and 500 hours. Strength losses after heat treatment at 1000 0 C for 100 and 500 hours, ranged from a high of 60% to as little as 7%. Additional heat treatments of 500 hours at 1100 and 1200 0 C were carried out on TTZ's which had strength losses of 15% or less after exposure to 1000 0 C

  3. Synthesis of Cyclic Py-Im Polyamide Libraries

    OpenAIRE

    Li, Benjamin C.; Montgomery, David C.; Puckett, James W.; Dervan, Peter B.

    2013-01-01

    Cyclic Py-Im polyamides containing two GABA turn units exhibit enhanced DNA binding affinity, but extensive studies of their biological properties have been hindered due to synthetic inaccessibility. A facile modular approach toward cyclic polyamides has been developed via microwave-assisted solid-phase synthesis of hairpin amino acid oligomer intermediates followed by macrocyclization. A focused library of cyclic polyamides 1–7 targeted to the androgen response element (ARE) and the estrogen...

  4. Electron beam induced modification of grafted polyamides

    International Nuclear Information System (INIS)

    Timus, D.M.; Brasoveanu, M.M.; Bradley, D.A.; Popov, A.M.

    1998-01-01

    It is well known that irradiation, when applied on its own or in combination with other physical and chemical treatments, can manifest in radiation damage to materials. Radiation processing technology focuses upon producing favourable modification of materials through use of relatively high dose and dose rates. Current interest is in modifying the thermal and electrical properties of textured polymers in an effort to improve safety and wear comfort of clothing. No less important is the production of textiles which are safe to use, both in homes and offices. Present investigations provide additional data in support of findings which show that polyamides, a particular class of textured polymer, are amenable to radiation processing. Accelerated electron beam irradiation of sheets of polyamide fibre results in induced grafting of acrylic and methacrylic acids. The degree of grafting is critically dependent upon irradiation dose and the extent of monomers dilution. Of particular importance is the high correlation which is found between degree of grafting and a decrease in the softening rate of the modified polyamide. A systematic modification of electrical conductivity is also observed. (author)

  5. Fracture toughness measurements on zirconia toughened ceramics

    International Nuclear Information System (INIS)

    El Sayed Ali, M.; Toft Soerensen, O.

    1986-12-01

    Three techniques for fracture toughness measurements on zirconia toughened ceramics were evaluated: the notched beam (NB) technique, the indentation fracture (IF) technique and the indentation strength in bending (ISB) technique. Using these techniques comparative measurements were performed on samples prepared by pressing (uniaxial) and sintering of four commercially available powder types. These were: Toya Soda (Japan) powders with the designations TZ3Y (2.86 mole% Y 2 O 3 ), TZ3YA (2.77 mole% Y 2 O 3 , 0.1 wt% Al 2 O 3 ) and TZ3Y20A (2.88 mole% Y 2 O 3 , 20 wt.% Al 2 O 3 ) and a powder supplied by Viking Chemicals (Denmark) designated as YP5Z-2.5 (2.5 mole% Y 2 O 3 ). The measurements showed that similar K Ic values were obtained with the IF- and ISB-techniques, which therefore are recommended for K Ic measurements. Too high values were, however, obtained with the NB-technique which therefore cannot be recommended. Finally, the measurements showed that a high temperature annealing is recommended prior to testing for the IF-technique. (author)

  6. Novel toughened polylactic acid nanocomposite: Mechanical, thermal and morphological properties

    International Nuclear Information System (INIS)

    Balakrishnan, Harintharavimal; Hassan, Azman; Wahit, Mat Uzir; Yussuf, A.A.; Razak, Shamsul Bahri Abdul

    2010-01-01

    The objective of the study is to develop a novel toughened polylactic acid (PLA) nanocomposite. The effects of linear low density polyethylene (LLDPE) and organophilic modified montmorillonite (MMT) on mechanical, thermal and morphological properties of PLA were investigated. LLDPE toughened PLA nanocomposites consisting of PLA/LLDPE blends, of composition 100/0 and 90/10 with MMT content of 2 phr and 4 phr were prepared. The Young's and flexural modulus improved with increasing content of MMT indicating that MMT is effective in increasing stiffness of LLDPE toughened PLA nanocomposite even at low content. LLDPE improved the impact strength of PLA nanocomposites with a sacrifice of tensile and flexural strength. The tensile and flexural strength also decreased with increasing content of MMT in PLA/LLDPE nanocomposites. The impact strength and elongation at break of LLDPE toughened PLA nanocomposites also declined steadily with increasing loadings of MMT. The crystallization temperature and glass transition temperature dropped gradually while the thermal stability of PLA improved with addition of MMT in PLA/LLDPE nanocomposites. The storage modulus of PLA/LLDPE nanocomposites below glass transition temperature increased with increasing content of MMT. X-ray diffraction and transmission electron microscope studies revealed that an intercalated LLDPE toughened PLA nanocomposite was successfully prepared at 2 phr MMT content.

  7. Kinetics of the deformation induced memory effect in polyamide-6

    NARCIS (Netherlands)

    Drongelen, van M.; Stroeks, A.A.M.; Peters, G.W.M.

    2015-01-01

    Nascent polyamide-6 shows a peculiar and irreversible effect; the quiescent crystallization kinetics on cooling are accelerated upon deformation in the melt, even after full relaxation of the melt. This phenomenon, known as the orientation (or better, deformation) induced memory effect of polyamide

  8. 21 CFR 177.2450 - Polyamide-imide resins.

    Science.gov (United States)

    2010-04-01

    ... Components of Articles Intended for Repeated Use § 177.2450 Polyamide-imide resins. Polyamide-imide resins identified in paragraph (a) of this section may be safely used as components of articles intended for... Safety and Applied Nutrition (HFS-200), Food and Drug Administration, 5100 Paint Branch Pkwy., College...

  9. Polyamides : hydrogen bonding, the Brill transition, and superheated water

    NARCIS (Netherlands)

    Dijkstra - Vinken, E.

    2008-01-01

    Aliphatic polyamide, commonly known as nylon, was the world’s first synthetic fiber and has found its largest application range in tires, carpets, stockings, upholstery, and adhesives. All polyamides have a recurring amide group (–CONH–) present in the molecular structure with hydrogen bonds between

  10. Ultrastrong Bioinspired Graphene-Based Fibers via Synergistic Toughening.

    Science.gov (United States)

    Zhang, Yuanyuan; Li, Yuchen; Ming, Peng; Zhang, Qi; Liu, Tianxi; Jiang, Lei; Cheng, Qunfeng

    2016-04-13

    Ultrastrong bioinspired graphene-based fibers are designed and prepared via synergistic toughening of ionic and covalent bonding. The tensile strength reaches up to 842.6 MPa and is superior to all other reported graphene-based fibers. In addition, its electrical conductivity is as high as 292.4 S cm(-1). This bioinspired synergistic toughening strategy supplies new insight toward the construction of integrated high-performance graphene-based fibers in the near future. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Synthesis and characterization of new soluble polyamides from Acenaphtohydrazinomercaptotriazole diamine

    Directory of Open Access Journals (Sweden)

    Hossein Mighani

    2015-08-01

    Full Text Available AbstractA diamine Acenaphtohydrazinomercaptotriazole (AHTD was synthesized in one step from acenaphthoqinone and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole. The diamin was characterized by FTIR, 1HNMR, 13CNMR and melting point. Diamin was used to prepare novel polyamides. The low temperature solution polycondensation of diamin with tow aromatic and tow aliphatic diacid chlorides afforded diamin-containing polyamides with inherent viscosities of 0.38–0.47 dl/g in DMF at 25 °C. The polyamides were generally soluble in a wide range of solvents such as dimethylformamide(DMF, N-Methylpyrolidone(NMP, tetrachloroethane (TCE, dimethylsulfoxide(DMSO and H2SO4. Thermal analysis showed that these polyamides were practically crustily and with Tg under 100 °C.

  12. Characterization and Solubilization of Pyrrole–Imidazole Polyamide Aggregates

    OpenAIRE

    Hargrove, Amanda E.; Raskatov, Jevgenij A.; Meier, Jordan L.; Montgomery, David C.; Dervan, Peter B.

    2012-01-01

    To optimize the biological activity of pyrrole–imidazole polyamide DNA-binding molecules, we characterized the aggregation propensity of these compounds through dynamic light scattering and fractional solubility analysis. Nearly all studied polyamides were found to form measurable particles 50–500 nm in size under biologically relevant conditions, while HPLC-based analyses revealed solubility trends in both core sequences and peripheral substituents that did not correlate with overall ionic c...

  13. Microstructure, Mechanical Properties, and Toughening Mechanisms of a New Hot Stamping-Bake Toughening Steel

    Science.gov (United States)

    Lin, Tao; Song, Hong-Wu; Zhang, Shi-Hong; Cheng, Ming; Liu, Wei-Jie; Chen, Yun

    2015-09-01

    In this article, the hot stamping-bake toughening process has been proposed following the well-known concept of bake hardening. The influences of the bake time on the microstructure and the mechanical properties of the hot stamped-baked part were studied by means of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and mechanical tests at room temperature. The results show that the amount of the retained austenite was nearly not changed by the bake process. Also observed were spherical Cu-rich precipitates of about 15 nm in martensite laths. According to the Orowan mechanism, their contribution of the Cu-rich precipitates to the strength is approximately 245 MPa. With the increase of the bake time, the tensile strength of the part was decreased, whereas both the ductility and the product of the tensile strength and ductility were increased then decreased. The tensile strength and ductility product and the tensile strength are as high as 21.9 GPa pct, 2086 MPa, respectively. The excellent combined properties are due to the transformation-induced plasticity effect caused by retained austenite.

  14. Feasibility of Using Multilayer Platelets as Toughening Agents

    Directory of Open Access Journals (Sweden)

    Yuan-Liang Chin

    2009-12-01

    Full Text Available It is known that the toughness of brittle ceramics can be improved significantly with the addition of hard platelets. In the present study, platelet-shape multilayer ceramic laminates are utilized as a toughening agent for alumina ceramics. They are prepared by laminating the BaTiO3-based ceramic tapes. Although the elastic modulus of the BaTiO3-based platelets is lower than that of the alumina matrix, and the platelets are also reactive to alumina at elevated temperatures, the weak platelets are found to exhibit the ability to deflect major matrix cracks by forming a large number of microcrack branches within the platelets, thus achieving the desired toughening effect.

  15. Toughening by nano-scaled twin boundaries in nanocrystals

    International Nuclear Information System (INIS)

    Zhou, Haofei; Qu, Shaoxing; Yang, Wei

    2010-01-01

    Joint enhancement on strength and toughness provides a cutting-edge research frontier for metals and alloys. Conventional strengthening methods typically lead to suppressed ductility and fracture toughness. In this study, large-scale atomic simulation on the fracture process is performed featuring nanocrystals embedded with nano-scaled twin boundaries (TBs). Four toughening mechanisms by nano-scaled TBs are identified: (i) crack blunting through dislocation accommodation along the nano-scaled TBs; (ii) crack deflection in a manner of intragranular propagation; (iii) daughter crack formation along the nano-scaled TBs that further enhances the toughness and (iv) curved TB planes owing to an excessive pileup of geometrically necessary dislocations. These toughening mechanisms jointly dictate the mechanical behavior of nano-structured materials, and provide insights into the application of nano-scaled TBs with an aim to simultaneously obtain enhanced strength and toughness. New approaches to introduce these coherent internal defects into the nanostructure of crystalline materials are also proposed

  16. Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites

    Science.gov (United States)

    Kanimozhi, K.; Sethuraman, K.; Selvaraj, V.; Alagar, M.

    2014-01-01

    Recent past decades have witnessed remarkable advances in composites with potential applications in biomedical devices, aerospace, textiles, civil engineering, energy, electronic engineering, and household products. Thermoset polymer composites have further enhanced and broadened the area of applications of composites. In the present work epoxy-BMI toughened-silica hybrid (RHA/DGEBA-BMI) was prepared using bismaleimide as toughener, bisphenol-A as matrix and a silica precursor derived from rice husk ash as reinforcement with glycidoxypropyltrimethoxysilane as coupling agent. Differential scanning calorimetry, electron microscopy, thermogravimetric analysis, and goniometry were used to characterize RHA/DGEBA-BMI composites developed in the present work. Tensile, impact and flexural strength, tensile and flexural modulus, hardness, dielectric properties were also studied and discussed. The hybrid nanocomposites possess the higher values of the glass transition temperature (Tg) and mechanical properties than those of neat epoxy matrix. PMID:25279372

  17. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    Science.gov (United States)

    Patel, Binay S.

    Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

  18. Pressureless sintering of whisker-toughened ceramic composites

    Science.gov (United States)

    Tiegs, T.N.

    1993-05-04

    A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

  19. Topological Toughening of graphene and other 2D materials

    Science.gov (United States)

    Gao, Huajian

    It has been claimed that graphene, with the elastic modulus of 1TPa and theoretical strength as high as 130 GPa, is the strongest material. However, from an engineering point of view, it is the fracture toughness that determines the actual strength of materials, as crack-like flaws (i.e., cracks, holes, notches, corners, etc.) are inevitable in the design, fabrication, and operation of practical devices and systems. Recently, it has been demonstrated that graphene has very low fracture toughness, in fact close to that of ideally brittle solids. These findings have raised sharp questions and are calling for efforts to explore effective methods to toughen graphene. Recently, we have been exploring the potential use of topological effects to enhance the fracture toughness of graphene. For example, it has been shown that a sinusoidal graphene containing periodically distributed disclination quadrupoles can achieve a mode I fracture toughness nearly twice that of pristine graphene. Here we report working progresses on further studies of topological toughening of graphene and other 2D materials. A phase field crystal method is adopted to generate the atomic coordinates of material with specific topological patterns. We then perform molecular dynamics simulations of fracture in the designed samples, and observe a variety of toughening mechanisms, including crack tip blunting, crack trapping, ligament bridging, crack deflection and daughter crack initiation and coalescence.

  20. Living Polycondensation: Synthesis of Well-Defined Aromatic Polyamide-Based Polymeric Materials

    KAUST Repository

    Alyami, Mram Z.

    2016-01-01

    Chain growth condensation polymerization is a powerful tool towards the synthesis of well-defined polyamides. This thesis focuses on one hand, on the synthesis of well-defined aromatic polyamides with different aminoalkyl pendant groups with low

  1. Effects of Green Tea Extract on Physicochemical and Antioxidant Properties of Polyamide Packaging Film

    OpenAIRE

    Ali Asghar Barzegaran; Maryam Jokar; Majid Javanmard Dakheli

    2014-01-01

    Polyamide 6 has been widely used in food packaging applications and also green tea contains amounts of antioxidant compounds. The aim of this study was investigation of green tea effects on properties of polyamide packaging polymer. Polyamide 6 was dissolved in methanol which was saturated with calcium chloride. The active packaging film was produced by incorporation of methanol green tea extracts at levels of 2.5, 5, 10 and 20% in polyamide solution by solution casting method. Mechanical and...

  2. Machining of glass fiber reinforced polyamide

    Directory of Open Access Journals (Sweden)

    2007-12-01

    Full Text Available The machinability of a 30 wt% glass fiber reinforced polyamide (PA was investigated by means of drilling tests. A disk was cut from an extruded rod and drilled on the flat surface: thrust was acquired during drilling at different drilling speed, feed rate and drill diameter. Differential scanning calorimetry (DSC and indentation were used to characterize PA so as to evaluate the intrinsic lack of homogeneity of the extruded material. In conclusion, it was observed that the chip formation mechanism affects the thrust dependence on the machining parameters. A traditional modeling approach is able to predict thrust only in presence of a continuous chip. In some conditions, thrust increases as drilling speed increases and feed rate decreases; this evidence suggests not to consider the general scientific approach which deals the machining of plastics in analogy with metals. Moreover, the thrust can be significantly affected by the workpiece fabrication effect, as well as by the machining parameters; therefore, the fabrication effect is not negligible in the definition of an optimum for the machining process.

  3. Development of polyamide-6/chitosan membranes for desalination

    Directory of Open Access Journals (Sweden)

    A. EL-Gendi

    2014-06-01

    Full Text Available This article deals with “developing novel polyamide-6/chitosan membranes for water desalting using wet phase inversion technique”, in which novel polyamide-6/chitosan membranes were prepared using an appropriate polymer concerning the national circumferences, along with the definition of different controlling parameters of the preparing processes and their effects on the characteristics of the produced membranes. Further, evaluation process of the fabricated sheets was undertaken. Preparation process was followed by assessment of the membrane structural characteristics; then the desalting performance of each prepared membrane was evaluated under different operating conditions in order to find the structure–property relationship. The results show that the membrane flux increases with the increase of operating pressure. The salt rejection and permeation flux have been enhanced this indicates that the chitosan (CS addition to the polyamide-6 (PA-6 membrane increases the membrane hydrophilic property. Hydraulic permeability coefficient is not stable and varies considerably with the operating pressure.

  4. Irradiation Crosslinking of Polyamides for the Electrical and Automotive Industry

    International Nuclear Information System (INIS)

    Gehring, J.

    2006-01-01

    Irradiation crosslinking of electrical cables and heat shrinkable tubes have been widely accepted in the automotive and electrical industry for a long time. Due higher demands regarding temperature resistance, arc resistance and good chemical resistance against oil and greases crosslinked injection moulded parts made out of polyamid and polybutylentherephtalate become also more and more interesting. Crosslinked polyamide can also replace thermosets for switches and offers therefore additional financial benefits. It will be shown on the basis of already realized projects, which basic requirements exist and how irradiation crosslinking can fulfil these demands

  5. Investigating the property profile of polyamide-alumina nanocomposite materials

    International Nuclear Information System (INIS)

    Sarwar, Muhammad Ilyas; Zulfiqar, Sonia; Ahmad, Zahoor

    2009-01-01

    Transparent sol-gel-derived nanocomposites were prepared by incorporating an alumina network into a polyamide matrix. Different amounts of aluminum butoxide were hydrolyzed and condensed to produce the alumina network. Thin composite films were characterized in terms of their optical, morphological, mechanical and thermomechanical properties. Tensile modulus, stress at both yield and break points, improved for alumina loadings of 5-10 wt.%. The glass transition temperature increased to 140 o C for nanocomposites containing 15 wt.% alumina. Scanning electron microscopy investigations indicated a uniform distribution of alumina in the polyamide matrix.

  6. Microwave sintering of zirconia toughened alumina at 28GHz

    International Nuclear Information System (INIS)

    Samandi, M.; Ji, H.; Miyake, S.

    1998-01-01

    Microwave radiation from a 10 kW, CW gyrotron operating at 28 GHz was employed to sinter 10% zirconia toughened alumina (ZTA) ceramic samples. It has been established that the use of millimetre wave radiation circumvents the difficulties encountered during the sintering of ceramics, i e. formation of hot spot, by radiation at industrially permissible frequency of 2.45GHz. Further, careful density measurement and microstructural characterisation of mm- wave and conventionally sintered samples by XRD, SEM and TEM has unequivocally demonstrated the effectiveness of mm-wave radiation for obtaining high density ceramics at lower sintering temperatures. Copyright (1998) Australasian Ceramic Society

  7. Extreme Toughening of Soft Materials with Liquid Metal.

    Science.gov (United States)

    Kazem, Navid; Bartlett, Michael D; Majidi, Carmel

    2018-05-01

    Soft and tough materials are critical for engineering applications in medical devices, stretchable and wearable electronics, and soft robotics. Toughness in synthetic materials is mostly accomplished by increasing energy dissipation near the crack tip with various energy dissipation techniques. However, bio-materials exhibit extreme toughness by combining multi-scale energy dissipation with the ability to deflect and blunt an advancing crack tip. Here, we demonstrate a synthetic materials architecture that also exhibits multi-modal toughening, whereby embedding a suspension of micron sized and highly deformable liquid metal (LM) droplets inside a soft elastomer, the fracture energy dramatically increases by up to 50x (from 250 ± 50 J m -2 to 11,900 ± 2600 J m -2 ) over an unfilled polymer. For some LM-embedded elastomer (LMEE) compositions, the toughness is measured to be 33,500 ± 4300 J m -2 , which far exceeds the highest value previously reported for a soft elastic material. This extreme toughening is achieved by (i) increasing energy dissipation, (ii) adaptive crack movement, and (iii) effective elimination of the crack tip. Such properties arise from the deformability of the LM inclusions during loading, providing a new mechanism to not only prevent crack initiation, but also resist the propagation of existing tears for ultra tough, soft materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Molecular nanomechanics of nascent bone: fibrillar toughening by mineralization

    Science.gov (United States)

    Buehler, Markus J.

    2007-07-01

    Mineralized collagen fibrils are highly conserved nanostructural building blocks of bone. By a combination of molecular dynamics simulation and theoretical analysis it is shown that the characteristic nanostructure of mineralized collagen fibrils is vital for its high strength and its ability to sustain large deformation, as is relevant to the physiological role of bone, creating a strong and tough material. An analysis of the molecular mechanisms of protein and mineral phases under large deformation of mineralized collagen fibrils reveals a fibrillar toughening mechanism that leads to a manifold increase of energy dissipation compared to fibrils without mineral phase. This fibrillar toughening mechanism increases the resistance to fracture by forming large local yield regions around crack-like defects, a mechanism that protects the integrity of the entire structure by allowing for localized failure. As a consequence, mineralized collagen fibrils are able to tolerate microcracks of the order of several hundred micrometres in size without causing any macroscopic failure of the tissue, which may be essential to enable bone remodelling. The analysis proves that adding nanoscopic small platelets to collagen fibrils increases their Young's modulus and yield strength as well as their fracture strength. We find that mineralized collagen fibrils have a Young's modulus of 6.23 GPa (versus 4.59 GPa for the collagen fibril), yield at a tensile strain of 6.7% (versus 5% for the collagen fibril) and feature a fracture stress of 0.6 GPa (versus 0.3 GPa for the collagen fibril).

  9. Molecular nanomechanics of nascent bone: fibrillar toughening by mineralization

    International Nuclear Information System (INIS)

    Buehler, Markus J

    2007-01-01

    Mineralized collagen fibrils are highly conserved nanostructural building blocks of bone. By a combination of molecular dynamics simulation and theoretical analysis it is shown that the characteristic nanostructure of mineralized collagen fibrils is vital for its high strength and its ability to sustain large deformation, as is relevant to the physiological role of bone, creating a strong and tough material. An analysis of the molecular mechanisms of protein and mineral phases under large deformation of mineralized collagen fibrils reveals a fibrillar toughening mechanism that leads to a manifold increase of energy dissipation compared to fibrils without mineral phase. This fibrillar toughening mechanism increases the resistance to fracture by forming large local yield regions around crack-like defects, a mechanism that protects the integrity of the entire structure by allowing for localized failure. As a consequence, mineralized collagen fibrils are able to tolerate microcracks of the order of several hundred micrometres in size without causing any macroscopic failure of the tissue, which may be essential to enable bone remodelling. The analysis proves that adding nanoscopic small platelets to collagen fibrils increases their Young's modulus and yield strength as well as their fracture strength. We find that mineralized collagen fibrils have a Young's modulus of 6.23 GPa (versus 4.59 GPa for the collagen fibril), yield at a tensile strain of 6.7% (versus 5% for the collagen fibril) and feature a fracture stress of 0.6 GPa (versus 0.3 GPa for the collagen fibril)

  10. The fracture properties and toughening mechanisms of bone and dentin

    Science.gov (United States)

    Koester, Kurt John

    The mechanical properties of bone and dentin and in particular their fracture properties, are the subject of intense research. The relevance of these properties is increasing as our population ages and fracture incidence impacts the lives of a greater portion of the population. A robust framework is needed to understand the fracture properties of bone and dentin to guide researchers as they attempt to characterize the effects of aging, disease, and pharmaceutical treatments on the properties of these mineralized tissues. In the present work, this framework is provided and applied to human bone, human dentin, and animal bone. In situ electron microscopy was also used to identify the salient toughening mechanisms in bone and dentin. It was found that bone and dentin are extrinsically toughened materials and consequently their fracture properties are best characterized utilizing a crack-growth resistance approach. A description of the different mechanical measurements commonly employed when using small animal models (rats and mice) to evaluate the influence of drug therapies on bone fragility is provided. A study where these properties were measured for a large population of wild-type rats and mice was also conducted. Given my findings, it was determined that for the most complete understanding of small animal bone it was necessary to measure strength and toughness. Strength measurements probe the flaw distribution and toughness measurements to evaluate the resistance to facture in the presence of a single dominant worst-case flaw.

  11. Toughening elastomers with sacrificial bonds and watching them break

    Science.gov (United States)

    Creton, Costantino

    2014-03-01

    Most unfilled elastomers are relatively brittle, in particular when the average molecular weight between crosslinks is lower than the average molecular weight between entanglements. We created a new class of tough elastomers by introducing isotropically prestretched chains inside ordinary acrylic elastomers by successive swelling and polymerization steps. These new materials combine a high entanglement density with a densely crosslinked structure reaching elastic moduli of 4 MPa and fracture strength of 25 MPa. The highly prestretched chains are the minority in the material and can break in the bulk of the material before catastrophic failure occurs, increasing the toughness of the material by two orders of magnitude up to 5 kJ/m2. To investigate the details of the toughening mechanism we introduced specific sacrificial dioxetane bonds in the prestretched chains that emit light when they break. In uniaxial extension cyclic experiments, we checked that the light emission corresponded exactly and quantitatively to the energy dissipation in each cycle demonstrating that short chains break first and long chains later. We then watched crack propagation in notched samples and mapped spatially the location of bond breakage ahead of the crack tip before and during propagation. This new toughening mechanism for elastomers creates superentangled rubbers and is ideally suited to overcome the trade-off between toughness and stiffness of ordinary elastomers. We gratefully acknowledge funding from DSM Ahead

  12. A study of thermal reactions of coal with polyamides

    Czech Academy of Sciences Publication Activity Database

    Straka, Pavel; Náhunková, Jana

    2004-01-01

    Roč. 1, č. 2 (2004), s. 239-243 ISSN 1211-1910 R&D Projects: GA AV ČR IAA2046902 Institutional research plan: CEZ:AV0Z3046908 Keywords : coal * kinetics * polyamides Subject RIV: CD - Macromolecular Chemistry

  13. The study of epoxy polyamide and polyvinyl resins as corrosion ...

    African Journals Online (AJOL)

    The corrosion resistance of two commonly used protective coatings (epoxy polyamide and polyvinyl resins) in the Niger Delta area of Nigeria has been assessed. The coatings on low carbon steel were subjected to varying conditions of pH, temperature and exposure time and the corrosion rates calculated. At a pH of 2, 3, 4, ...

  14. Microporous membranes from polyolefin-polyamide blend materials

    Czech Academy of Sciences Publication Activity Database

    Meier-Haack, J.; Valko, M.; Lunkwitz, K.; Bleha, Miroslav

    2004-01-01

    Roč. 163, 1-3 (2004), s. 215-221 ISSN 0011-9164. [Membrane Science and Technology Conference PERMEA 2003. Tatranské Matliare, 07.09.2003-11.09.2003] Institutional research plan: CEZ:AV0Z4050913 Keywords : microporous membranes * polypropylene polyamide blends * reactive extrusion Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.057, year: 2004

  15. Effects of Green Tea Extract on Physicochemical and Antioxidant Properties of Polyamide Packaging Film

    Directory of Open Access Journals (Sweden)

    Ali Asghar Barzegaran

    2014-08-01

    Full Text Available Polyamide 6 has been widely used in food packaging applications and also green tea contains amounts of antioxidant compounds. The aim of this study was investigation of green tea effects on properties of polyamide packaging polymer. Polyamide 6 was dissolved in methanol which was saturated with calcium chloride. The active packaging film was produced by incorporation of methanol green tea extracts at levels of 2.5, 5, 10 and 20% in polyamide solution by solution casting method. Mechanical and barrier properties of polyamide films were investigated using ASTM standards and antioxidant activity of polyamide films was evaluated using DPPH method. Results indicated that green tea extract increased antioxidant properties and tensile and young modulus of polyamide films. Oxygen and water vapor permeability of films were decreased by incorporation of green tea extract into polyamide matrix. Green tea extract improved barrier and tensile properties of polyamide films, however elongation at break reduced as increasing of green tea extract in polyamide-based films significantly (P<0.05.

  16. Enhanced Damage Tolerance High Temperature Composite Using a Biomimetic Toughening System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight composite structures are required to provide space vehicles with increased thrust-to-weight ratio and durability. New methods for toughening composites...

  17. Theoretical and experimental analysis of the toughening behavior of whisker reinforcement in ceramic matrix composites

    International Nuclear Information System (INIS)

    Becher, P.F.; Hsueh, C.H.; Angelini, P.; Tiegs, T.N.

    1988-01-01

    Analytical solutions are presented describing the experimentally verified toughening of whisker reinforced ceramics. Clear insights are provided into the interrelationships of whiskers, matrices, and interfaces in the case of strong interfaces with minimized whisker pullout

  18. Fracture and Toughening of Composites of Polymers and Nanoscale Inorganic and Organic Fillers

    National Research Council Canada - National Science Library

    Chung, Neal

    2001-01-01

    The objectives of the project were to investigate the mechanical properties and particularly the fracture mechanisms of a number of nanocomposites, and to discover possible approaches to their toughening...

  19. Tribological properties of toughened zirconia-based ceramics

    International Nuclear Information System (INIS)

    Stachowiak, G.W.; Stachowiak, G.B.

    1991-01-01

    The physical and mechanical properties of toughened zirconia ceramics are briefly characterized and described with a special emphasis on their tribological behaviour. The wear and friction properties of PSZ and TZP ceramics at room and elevated temperatures are described. The influence of the environment on the tribological characteristics of zirconia ceramics is discussed. Both lubricated and unlubricated conditions for ceramic/ceramic and metal/ceramic sliding contacts are analysed. One of the main, and as yet unresolved problems, lubrication of ceramic at elevated temperatures and/or space environment, is addressed and the possible solutions to the problem are suggested. The critical needs in the research and development area of improving the tribological properties of zirconia ceramics are defined and its future market potentials stated. 30 refs., 2 tabs., 4 figs

  20. Elevated Temperature Testing and Modeling of Advanced Toughened Ceramic Materials

    Science.gov (United States)

    Keith, Theo G.

    2005-01-01

    The purpose of this report is to provide a final report for the period of 12/1/03 through 11/30/04 for NASA Cooperative Agreement NCC3-776, entitled "Elevated Temperature Testing and Modeling of Advanced Toughened Ceramic Materials." During this final period, major efforts were focused on both the determination of mechanical properties of advanced ceramic materials and the development of mechanical test methodologies under several different programs of the NASA-Glenn. The important research activities made during this period are: 1. Mechanical properties evaluation of two gas-turbine grade silicon nitrides. 2) Mechanical testing for fuel-cell seal materials. 3) Mechanical properties evaluation of thermal barrier coatings and CFCCs and 4) Foreign object damage (FOD) testing.

  1. An implementation of 3D viscoelatic behavior for glass during toughening

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2007-01-01

    The paper presents a derivation of an incremental formulation for the thermorheological material behavior of glass during the toughening process. The objective of this paper is to provide a constitutive relationship and a discussion for implementing a 3D thermo-viscoelastic material in a numerica......-Software ABAQUS. It has to be emphasized that other phenomena than stress relaxation are present during the toughening process, however, the purpose of this paper is only to provide a model for the thermo viscoelastic behavior....

  2. Tumor Repression of VCaP Xenografts by a Pyrrole-Imidazole Polyamide.

    Directory of Open Access Journals (Sweden)

    Amanda E Hargrove

    Full Text Available Pyrrole-imidazole (Py-Im polyamides are high affinity DNA-binding small molecules that can inhibit protein-DNA interactions. In VCaP cells, a human prostate cancer cell line overexpressing both AR and the TMPRSS2-ERG gene fusion, an androgen response element (ARE-targeted Py-Im polyamide significantly downregulates AR driven gene expression. Polyamide exposure to VCaP cells reduced proliferation without causing DNA damage. Py-Im polyamide treatment also reduced tumor growth in a VCaP mouse xenograft model. In addition to the effects on AR regulated transcription, RNA-seq analysis revealed inhibition of topoisomerase-DNA binding as a potential mechanism that contributes to the antitumor effects of polyamides in cell culture and in xenografts. These studies support the therapeutic potential of Py-Im polyamides to target multiple aspects of transcriptional regulation in prostate cancers without genotoxic stress.

  3. The influence of multiscale fillers reinforcement into impact resistance and energy absorption properties of polyamide 6 and polypropylene nanocomposite structures

    International Nuclear Information System (INIS)

    Silva, Francesco; Njuguna, James; Sachse, Sophia; Pielichowski, Krzysztof; Leszczynska, Agnieszka; Giacomelli, Marco

    2013-01-01

    Highlights: ► Significant improvement in PA composites impact resistance performance. ► Decrease in energy absorption capabilities of PP, this phenomenon is explained. ► Positive effects on mechanical and interphase properties of the matrix material. ► Transition from brittle to ductile fracture mode established. ► Two different toughening mechanisms were observed and explained. - Abstract: Three-phase composites (thermoplastic polymer, glass-fibres and nano-particles) were investigated as an alternative to two-phase (polymer and glass-fibres) composites. The effect of matrix and reinforcement material on the energy absorption capabilities of composite structures was studied in details in this paper. Dynamic and quasi-static axial collapse of conical structures was conducted using a high energy drop tower, as well as Instron universal testing machine. The impact event was recorded using a high-speed camera and the fracture surface was investigated with scanning electron microscopy (SEM). Attention was directed towards the relation between micro and macro fracture process with crack propagation mechanism and energy absorbed by the structure. The obtained results indicated an important influence of filler and matrix material on the energy absorption capabilities of the polymer composites. A significant increase in specific energy absorption (SEA) was observed in polyamide 6 (PA6) reinforced with nano-silica particles and glass-spheres, whereas addition of montmorillonite (MMT) caused a decrease in that property. On the other hand, very little influence of the secondary reinforcement on the energy absorption capabilities of polypropylene (PP) composites was found

  4. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    International Nuclear Information System (INIS)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan; Cheng, Jue; Zhang, Junying

    2013-01-01

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T g and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar

  5. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Cheng, Jue, E-mail: chengjue@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Junying, E-mail: zjybuct@gmail.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2013-02-20

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T{sub g} and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar.

  6. Polyamide 6/clay membranes: effect of precipitation bath in morphology

    International Nuclear Information System (INIS)

    Ferreira, Rodholfo da S.B.; Pereira, Caio H. do O; Leite, Amanda M.D.; Araujo, Edcleide M.; Lira, Helio L.

    2015-01-01

    Polyamide 6 membranes and their nanocomposites with 5% clay were obtained by the phase inversion method and the precipitation was made in distilled water bath and also in the mixture of solvent and distilled water. The nanocomposites were characterized by XRD and membranes by SEM. By XRD analysis, it was found that the obtained nanocomposite presents a structure probably exfoliated and / or partially exfoliated, it was also possible to observe the presence of two characteristic peaks (α and γ) of the polyamide 6 phases. In the SEM micrographs it was seen that the presence of clay promote alterations in morphology, size and distribution of pores. The presence of acid in the precipitation bath leads to a significant decrease in the filter layer, but also an increase in the quantity of pore size. (author)

  7. Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites

    International Nuclear Information System (INIS)

    Paz, Rene A.; Leite, Amanda M.D.; Medeirosa, Vanessa da N.; Araujo, Edcleide M.; Melo, Tomas J.A.; Pessan, Luiz A.

    2010-01-01

    Nanocomposites of polymer/clay have had much attention in recent years, particularly those developed with layered silicates due to the need of engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in crystalline structure of polymer matrices has been studied and has been observed that they affect the crystalline behavior and the physical and mechanical properties. In this study, nanocomposites of polyamide 6 were obtained by the melt intercalation method, using a regional bentonite modified with a quaternary ammonium salt in an amount of 3% by weight. XRD results showed that incorporation of salt among the layers of clay, making it organophilic and obtaining exfoliated and/or partially exfoliated structures. The impact properties of the nanocomposites showed inferior in relation to pure polyamide, in other words, lost of toughness. (author)

  8. Investigation into radiation-chemical transformations of polyamide P-54

    International Nuclear Information System (INIS)

    Khabarov, V.N.; Kozlov, L.L.; Panchenkov, G.M.

    1981-01-01

    Investigation results of alcohol-soluble polyamide P-54 radiolysis by different physicochemical methods are presented. It has been established that under the effect of γ-radiation certain processes take place in polyamide, which are connected with branching, structurization and destruction of macromolecules. Radiation-chemical yields of gaseous products during irradiation in the air and in vacuum at irradiation temperatures from 273 to 393 K are calculated. The ratio of the rates of lacing and destruction processes is found and radiation yields of the processes are determined. Under irradiation in the air at temperatures >333 K chain oxidation of P-54 takes place and the growth of pe-- roxide compounds with 8 molecules/100 eV at 298 K up to 135 mole-- cules/100 eV at irradiation temperature 373 K testifies to the fact

  9. Tumor Repression of VCaP Xenografts by a Pyrrole-Imidazole Polyamide

    OpenAIRE

    Hargrove, Amanda E.; Martinez, Thomas F.; Hare, Alissa A.; Kurmis, Alexis A.; Phillips, John W.; Sud, Sudha; Pienta, Kenneth J; Dervan, Peter B.

    2015-01-01

    Pyrrole-imidazole (Py-Im) polyamides are high affinity DNA-binding small molecules that can inhibit protein-DNA interactions. In VCaP cells, a human prostate cancer cell line overexpressing both AR and the TMPRSS2-ERG gene fusion, an androgen response element (ARE)-targeted Py-Im polyamide significantly downregulates AR driven gene expression. Polyamide exposure to VCaP cells reduced proliferation without causing DNA damage. Py-Im polyamide treatment also reduced tumor growth in a VCaP mouse ...

  10. Synthesis and Characterization of New Polyamides from 1,2-Bis hydrazine Derivatives

    International Nuclear Information System (INIS)

    Salaha, A.; Abdel-Bary, E.M.; Kandilea, N.G.

    2005-01-01

    Preparation of polyamides having different chemical structures allows obtaining new materials with different mechanical and physical properties. The difference in the chemical structure depends mainly on the starting reactants used in condensation polymerization of polyamides. In this paper the synthesis of new polyamides based on the condensation polymerization of 1,2- Bis(3-carboxyacryloyl or carboxybenzoyl) hydrazine derivatives and various diamines has been described. The polymers obtained were characterized using spectroscopic and X-ray analysis. Besides thermal stability and electrical conductivity have been evaluated and correlated with the chemical structure of the polyamides obtained

  11. Kinetics of copyrolysis of coal with polyamide 6

    Czech Academy of Sciences Publication Activity Database

    Straka, Pavel; Náhunková, Jana; Brožová, Zuzana

    2004-01-01

    Roč. 71, č. 1 (2004), s. 213-221 ISSN 0165-2370. [Pyrolysis 2002, 15th International Symposium on Analytical and Applied Pyrolysis. Leoben, 17.09.2002-20.09.2002] R&D Projects: GA AV ČR IBS3046004 Institutional research plan: CEZ:AV0Z3046908 Keywords : coal * kinetics * polyamide 6 Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.352, year: 2004

  12. Factors affecting polyamide prototypes design of Albedo dosemeters

    International Nuclear Information System (INIS)

    Martins, M.M.; Mauricio, C.L.P.; Fonseca, E.S.

    1996-01-01

    This work studies the most important factors which affect the response of albedo neutron dosemeters containing LiF TLDs with the aim to improve their sensitivity. It includes tests of thickness and shape of the polyamide moderator body prototypes, albedo window diameter and TLD position inside the moderator. Analyzing the results, an albedo neutron dosemeter prototype, B 4 C covered, was developed. The prototype has a response three times higher than the albedo dosemeter now in use in Brazil. (author)

  13. Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites

    International Nuclear Information System (INIS)

    Paz, Rene Anisio; Araujo, Edcleide Maria; Tomas Jeferson Alves; Amanda Damiao; Medeiros, Vanessa da Nobrega; Pessan, Luiz Antonio

    2012-01-01

    Nanocomposites of polymer/clay have had much attention in recent years, particularly those developed with layered silicates due to the need of engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in crystalline structure of polymer matrices has been studied and has been observed that it affects the crystalline behavior and the physical and mechanical properties. In this study, nanocomposites of polyamide 6 were obtained by the melt intercalation method, using a Brazilian bentonite modified with a quaternary ammonium salt. X-Ray Diffraction (XRD) results showed the incorporation of salt among the layers of clay, making it organophilic and that the nanocomposites presented exfoliated and/or partially exfoliated structures and confirmed by transmission electron microscopy (TEM). By thermogravimetry (TG), the results indicated that the presence of clay increased the thermal stability of polyamide 6. The impact properties of the nanocomposites showed inferior values in relation to the pure polyamide, in other words, decrease the toughness. (author)

  14. Structure and mechanical properties of polyamide 6/Brazilian clay nanocomposites

    Directory of Open Access Journals (Sweden)

    Amanda Melissa Damião Leite

    2009-06-01

    Full Text Available Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.

  15. Synthesis and Properties of Cross-Linked Polyamide Aerogels

    Science.gov (United States)

    Williams, Jarrod C.; Meador, Mary Ann; McCorkle, Linda

    2015-01-01

    We report the first synthesis of cross-linked polyamide aerogels through step growth polymerization using a combination of diamines, diacid chloride and triacid chloride. Polyamide oligomers endcapped with amines are prepared as stable solutions in N-methylpyrrolidinone from several different diamine precursors and 1,3-benzenedicarbonyl dichloride. Addition of 1,3,5-benzenetricarbonyl trichloride yields gels which form in under five minutes according to the scheme shown. Solvent exchange of the gels into ethanol, followed by drying using supercritical CO2 extraction gives colorless aerogels with densities around 0.1 to 0.2 gcm3. Thicker monolithes of the polyamide aerogels are stiff and strong, while thin films of certain formulations are highly flexible, durable, and even translucent. These materials may have use as insulation for deployable space structures, rovers, habitats or extravehicular activity suits as well as in many terrestrial applications. Strucure property relationships of the aerogels, including surface area, mechanical properties, and thermal conductivity will be discussed.

  16. Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Paz, Rene Anisio; Araujo, Edcleide Maria; Tomas Jeferson Alves; Amanda Damiao; Medeiros, Vanessa da Nobrega [Federal University of Campina Grande (CCT/UFCG), Campina Grande, PB (Brazil). Centro de Ciencias e Tecnologia; Pessan, Luiz Antonio [Federal University of Sao Carlos (DEMa/UFSCar), SP (Brazil). Materials Engineering Department

    2012-07-15

    Nanocomposites of polymer/clay have had much attention in recent years, particularly those developed with layered silicates due to the need of engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in crystalline structure of polymer matrices has been studied and has been observed that it affects the crystalline behavior and the physical and mechanical properties. In this study, nanocomposites of polyamide 6 were obtained by the melt intercalation method, using a Brazilian bentonite modified with a quaternary ammonium salt. X-Ray Diffraction (XRD) results showed the incorporation of salt among the layers of clay, making it organophilic and that the nanocomposites presented exfoliated and/or partially exfoliated structures and confirmed by transmission electron microscopy (TEM). By thermogravimetry (TG), the results indicated that the presence of clay increased the thermal stability of polyamide 6. The impact properties of the nanocomposites showed inferior values in relation to the pure polyamide, in other words, decrease the toughness. (author)

  17. POLYAMIDE 6 WITH A FLAME RETARDANT ENCAPSULATED BY POLYAMIDE 66: FLAME RETARDATION, THERMO-DECOMPOSITION AND THE POTENTIAL MECHANISM

    Institute of Scientific and Technical Information of China (English)

    Wei-cheng Xiong; Li Chen; Bin Zhao; De-yi Wang; Yu-zhong Wang

    2012-01-01

    A novel encapsulated flame retardant containing phosphorus-nitrogen (MSMM-Al-P) was prepared by encapsulating with polyamide 66 (PA66-MSMM-Al-P) for the flame retardation of polyamide 6 (PA6).The structure and thermal properties of PA66-MSMM-Al-P were characterized by Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy and thermogravimetric analysis.The flammability of PA6 containing' flame retardants (MSMMAl-P and PA66-MSMM-Al-P) was investigated by the limiting oxygen index test,vertical burning test and cone calorimeter.The flame retardancy and cone calorimetric analyses suggested a synergistic effect between PA66 and MSMM-Al-P in the flame-retardant PA6.Thermal stability of the flame-retardant PA6 was also investigated.

  18. Simulating the growth process of aromatic polyamide layer by monomer concentration controlling method

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Yan [Vontron Technology Co., Ltd., Guiyang 550018, Guizhou (China); Liang, Songmiao, E-mail: liangsongmiao@vontron.com.cn [Vontron Technology Co., Ltd., Guiyang 550018, Guizhou (China); Wu, Zongce; Cai, Zhiqi [Vontron Technology Co., Ltd., Guiyang 550018, Guizhou (China); Zhao, Ning [National Laboratory of Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (ICCAS), Beijing 100190 (China)

    2014-09-30

    Highlights: • A concentration controlling method to simulate the growth process of polyamide layer was developed. • The surface structure features and properties of polyamide layer at its different growth stages were systematically investigated. • Structure transition from spherical aggregator to leaf-like to typical ridge-and-valley was observed. • The performance of RO membrane is closely related to the structure of polyamide. - Abstract: With the wide distribution and gradual increase of TMC concentration (C{sub TMC}) from 1 × 10{sup −4} wt% to 2.5 × 10{sup −1} wt%, the main purpose of this work is to simulate the surface structure and properties of polyamide layer of reverse osmosis membranes at its different growth stage. The surface structure and properties of the resulted membranes were then characterized by atomic force microscopy (AFM), scanning electron microscope (SEM), attenuated total reflectance infrared (ATR-IR) spectroscopy, drop shape analysis system and electrokinetic analyzer. The structure growth of polyamide layer underwent in turn three different stages including spherical aggregator, leaf-like and typical ridge-valley structure. Spherical aggregator is the intrinsic structure in the inner layer of polyamide while leaf-like structure is transitional on the outmost polyamide layer. Furthermore, to clarify the effect of the structure change on the properties of polyamide layer, contact angle and zeta potential in the surface of polyamide layer were studied. Hydrophilic surface of polyamide layer is accessible at higher TMC concentration because of the presence of negative charged groups. Performances of the membranes were further measured with an emphasis on studying its structure–performance relationship during the growth process of polyamide layer.

  19. Graphene nanosheet-induced toughening of yttria-stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jianan; Chen, Yao; Huang, Qiqi [Soochow University, School of Mechanical and Electric Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China)

    2017-01-15

    Graphene nanosheet (GNS)-reinforced yttria-stabilized tetragonal zirconia polycrystals (TZP) were synthesized using spark plasma sintering (SPS), and the influences of the added GNSs on microstructure evolution and the microscopic mechanical properties of the sintered composites were investigated. Raman spectroscopy and microstructure observation corroborated that these added GNSs, which can survive the harsh SPS processing condition, homogeneously distribute in the matrix of all composites to hinder significantly the grain growth. In comparison with the monolithic TZP, the indentation fracture toughness of a GNS/TZP composite reaches maximum value and increases by up to ∝36% (from ∝4.1 to ∝5.6 MPa m{sup 0.5}) even at 0.5% weight fraction, GNS pullout, crack bridging, crack deflection, and crack branching are responsible for the increased fracture toughness. The computed energy dissipation by GNS pullout decreases with increasing the number of graphene layers due to weak bonding between them, and therefore, graphene agglomeration would impair toughening effect. Moreover, scratch studies suggest that GNS/TZP composites exhibit improved scratch resistance due to the fact that GNSs are promising reinforcing and lubricating nanofillers in ceramic composites. (orig.)

  20. Moisture curable toughened poly(lactide utilizing vinyltrimethoxysilane based crosslinks

    Directory of Open Access Journals (Sweden)

    J. Schneider

    2016-10-01

    Full Text Available Vinyltrimethoxysilane (VTMOS was grafted on to the backbone of poly(lactide (PLA through a free radical grafting reaction using reactive extrusion (REX processing. The methoxy groups of the silane provide the modified PLA sites for crosslinking through a moisture induced pathway. VTMOS grafting efficiencies of up to 90% were obtained. The newly created methoxy functionality of the modified PLA readily undergoes hydrolysis and condensation forming siloxane crosslinks in the material. Crosslinking with VTMOS exhibited improved modulus, strength, and impact toughness while showing a decrease in ductility. Incorporating silanol-terminated poly(dimethylsiloxane (OH-PDMS resulted in the formation of longer siloxane crosslinks. These samples showed an increase in modulus and impact toughness due to the crosslinking, while the longer siloxane linkages resulted in improved ductility and tensile toughness. This is unusual for polymers toughened through crosslinking reactions. Scanning Electron Microscopy (SEM of the fractured surfaces showed the presence of these elongated siloxane crosslinks. This enhanced ability for the modified PLA to deform and absorb energy results in the increase in both impact and tensile toughness.

  1. Toughening mechanisms in interfacially modified HDPE/thermoplastic starch blends.

    Science.gov (United States)

    Taguet, Aurélie; Bureau, Martin N; Huneault, Michel A; Favis, Basil D

    2014-12-19

    The mechanical behavior of polymer blends containing 80 wt% of HDPE and 20 wt% of TPS and compatibilized with HDPE-g-MA grafted copolymer was investigated. Unmodified HDPE/TPS blends exhibit high fracture resistance, however, the interfacial modification of those blends by addition of HDPE-g-MA leads to a dramatic drop in fracture resistance. The compatibilization of HDPE/TPS blends increases the surface area of TPS particles by decreasing their size. It was postulated that the addition of HDPE-g-MA induces a reaction between maleic anhydride and hydroxyl groups of the glycerol leading to a decrease of the glycerol content in the TPS phase. This phenomenon increases the stiffness of the modified TPS particles and stiffer TPS particles leading to an important reduction in toughness and plastic deformation, as measured by the EWF method. It is shown that the main toughening mechanism in HDPE/TPS blends is shear-yielding. This article demonstrates that stiff, low diameter TPS particles reduce shear band formation and consequently decrease the resistance to crack propagation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Polyamide membranes with nanoscale Turing structures for water purification

    Science.gov (United States)

    Tan, Zhe; Chen, Shengfu; Peng, Xinsheng; Zhang, Lin; Gao, Congjie

    2018-05-01

    The emergence of Turing structures is of fundamental importance, and designing these structures and developing their applications have practical effects in chemistry and biology. We use a facile route based on interfacial polymerization to generate Turing-type polyamide membranes for water purification. Manipulation of shapes by control of reaction conditions enabled the creation of membranes with bubble or tube structures. These membranes exhibit excellent water-salt separation performance that surpasses the upper-bound line of traditional desalination membranes. Furthermore, we show the existence of high water permeability sites in the Turing structures, where water transport through the membranes is enhanced.

  3. Morphology study of polyamide 6/bentonite clay nanocomposites

    International Nuclear Information System (INIS)

    Paz, Rene A.; Araujo, Edcleide M.; Melo, Tomas J.A.; Leite, Amanda M.D.; Medeiros, Vanessa Nobrega; Pessan, Luiz A.; Passador, Fabio R.

    2011-01-01

    Polymer/clay nanocomposites have had much attention in recent years, especially those developed with layered silicates, due to the need for engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in the crystalline structure of polymer matrices has been studied and it has been observed that it affects the behavior of crystalline and therefore the mechanical and physical properties. In this study, polyamide 6 nanocomposites were obtained by the melt intercalation technique, using regional bentonite clay modified with a quaternary ammonium salt in an amount of 3% by weight. XRD and TEM tests showed obtaining nanocomposites with exfoliated structures (author)

  4. Grafting of acrylamide onto synthetic co polyamide by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hamoud, M R; Qamhieyh, E A [Chemistry Dept., College of Ibn Al-Haitham Baghdad university-Adhamiyah-Baghdad- (Iraq)

    1995-10-01

    Grafted copolymer was prepared by using gamma irradiation to graft acrylamide onto polymeric molecule prepared by interfacial condensation between two diamine molecules like 1,2 diamino propane and 1,6 diamino-hexane in aqueous layer with sebacoyl chloride in organic layer. The resulted co polyamide was grafted with acrylamide using gamma irradiation. The optimum conditions of grafting reaction were found, also various factors such as the effect of solvents, redox systems and the role water on the radiochemical grafting were studied. Many techniques were used in the characterization of the copolymer before and after grafting. 8 figs.,.

  5. A Polyamide Inhibits Replication of Vesicular Stomatitis Virus by Targeting RNA in the Nucleocapsid

    Energy Technology Data Exchange (ETDEWEB)

    Gumpper, Ryan H.; Li, Weike; Castañeda, Carlos H.; Scuderi, M. José; Bashkin, James K.; Luo, Ming; Dutch, Rebecca Ellis

    2018-02-07

    Polyamides have been shown to bind double-stranded DNA by complementing the curvature of the minor groove and forming various hydrogen bonds with DNA. Several polyamide molecules have been found to have potent antiviral activities against papillomavirus, a double-stranded DNA virus. By analogy, we reason that polyamides may also interact with the structured RNA bound in the nucleocapsid of a negative-strand RNA virus. Vesicular stomatitis virus (VSV) was selected as a prototype virus to test this possibility since its genomic RNA encapsidated in the nucleocapsid forms a structure resembling one strand of an A-form RNA duplex. One polyamide molecule, UMSL1011, was found to inhibit infection of VSV. To confirm that the polyamide targeted the nucleocapsid, a nucleocapsid-like particle (NLP) was incubated with UMSL1011. The encapsidated RNA in the polyamide-treated NLP was protected from thermo-release and digestion by RNase A. UMSL1011 also inhibits viral RNA synthesis in the intracellular activity assay for the viral RNA-dependent RNA polymerase. The crystal structure revealed that UMSL1011 binds the structured RNA in the nucleocapsid. The conclusion of our studies is that the RNA in the nucleocapsid is a viable antiviral target of polyamides. Since the RNA structure in the nucleocapsid is similar in all negative-strand RNA viruses, polyamides may be optimized to target the specific RNA genome of a negative-strand RNA virus, such as respiratory syncytial virus and Ebola virus.

    IMPORTANCENegative-strand RNA viruses (NSVs) include several life-threatening pathogens, such as rabies virus, respiratory syncytial virus, and Ebola virus. There are no effective antiviral drugs against these viruses. Polyamides offer an exceptional opportunity because they may be optimized to target each NSV. Our studies on vesicular stomatitis virus, an NSV, demonstrated that a polyamide molecule could specifically target the viral RNA in the nucleocapsid and inhibit

  6. Investigation on fracture behavior and mechanisms of DGEBF toughened by CTBN

    Science.gov (United States)

    Wang, Lulu; Tan, Yefa; Wang, Haitao; Gao, Li; Xiao, Chufan

    2018-05-01

    Carboxyl-terminated butadiene-co-acrylonitrile (CTBN) was used as the toughener to improve the mechanical performance and fracture toughness of diglycidyl ether of bisphenol F (DGEBF) by prereacted approach. The results show that the chemical bonding interface was formed between DGEBF and CTBN particles in the prepolymerization reaction process, which remarkably enhances the fracture toughness of the composites. Based on the qualitative and quantitative analyses, it shows the main toughening mechanisms are the plastic shear banding effect resulted from the plastic deformation of the EP matrix and the plastic void expansion because of the debonding of CTBN particles from the EP matrix.

  7. Biologically inspired autonomous structural materials with controlled toughening and healing

    Science.gov (United States)

    Garcia, Michael E.; Sodano, Henry A.

    2010-04-01

    the system to its original operating state. The entire system will effectively detect, self toughen, and subsequently heal damage as biological materials such as bone does.

  8. Electron beam radiation effects on recycled polyamide-6

    International Nuclear Information System (INIS)

    Evora, Maria Cecilia; Silva, Leonardo G. de Andrade e

    2001-01-01

    Applications of electron beam processing in the treatment of polymers are commonly used. The interaction of high energy radiation with polymers may cause permanent modifications in the polymer's physicochemical structure. The induced modifications may result in degradation of the polymer or in improvement of its properties (crosslinking), which are simultaneous and competing processes, depending on the radiation dose utilized. Crosslinking occurs more readily in the polymer's amorphous content and this process makes the glass transition temperature (Tg) of the polymers to increase. Successive recycling cycles promote changes in polymers properties, such as breaking of structure, molecular weight reduction, melt index increase and mechanical resistance reduction. The polyamide-6 resin was recycled for three successive recycling cycles and thi polyamide-6 specimens were molded by the process of injection molding. These specimens were irradiated at the Nuclear Energetic Research Institute (IPEN) radiation facility, on a JOB 188 model accelerator, with a 1.5 MeV electron beam, doses of 200, 300, 400, 500 and 600 kGy, and dose rate of 22.61 kGy/s. The DMA tests were performed using DMA-983 equipment from TA Instruments and two heatings were adopted in order to eliminate the moisture absorption. The X-ray diffraction analysis wa carried out at the Philips PW 1830 model equipment

  9. Thin Film Polyamide Membranes with Photoresponsive Antibacterial Activity

    KAUST Repository

    Duong, Phuoc H. H.

    2017-08-09

    Membranes containing a photosensitizer molecule as part of the selective layer are proposed with demonstrated anti-biofouling activity. For the membrane preparation, mixtures of an amine-functionalized photosensitizer molecule, (5,10,15,20-(tetra-4-aminophenyl)porphyrin) and m-phenylene diamine (MPD) reacted with trimesoyl chloride (TMC) by interfacial polymerization to form thin polyamide films on top of an asymmetric porous support. A highly permeable membrane (35.4 Lm−2h−1bar−1) with 99 % rejection of Brilliant Blue R (826 g/mol) was obtained using 0.25 wt% porphyrin and 0.75 wt% MPD as amine monomers. Under visible light exposure, singlet oxygen (1O2) is generated in the porphyrin containing-polyamide film, reaching the bacteria in the feed by diffusion and enhancing the biofouling resistance and anti-microbial activity. Anti-biofouling and anti-microbial photoactivity in solution are demonstrated on Staphylococcus aureus at different porphyrin concentrations and light exposure time.

  10. Thin Film Polyamide Membranes with Photoresponsive Antibacterial Activity

    KAUST Repository

    Duong, Phuoc H. H.; Hong, Pei-Ying; Musteata, Valentina-Elena; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira

    2017-01-01

    Membranes containing a photosensitizer molecule as part of the selective layer are proposed with demonstrated anti-biofouling activity. For the membrane preparation, mixtures of an amine-functionalized photosensitizer molecule, (5,10,15,20-(tetra-4-aminophenyl)porphyrin) and m-phenylene diamine (MPD) reacted with trimesoyl chloride (TMC) by interfacial polymerization to form thin polyamide films on top of an asymmetric porous support. A highly permeable membrane (35.4 Lm−2h−1bar−1) with 99 % rejection of Brilliant Blue R (826 g/mol) was obtained using 0.25 wt% porphyrin and 0.75 wt% MPD as amine monomers. Under visible light exposure, singlet oxygen (1O2) is generated in the porphyrin containing-polyamide film, reaching the bacteria in the feed by diffusion and enhancing the biofouling resistance and anti-microbial activity. Anti-biofouling and anti-microbial photoactivity in solution are demonstrated on Staphylococcus aureus at different porphyrin concentrations and light exposure time.

  11. Characterization of isolated polyamide thin films of RO and NF membranes using novel TEM techniques

    KAUST Repository

    Pacheco, Federico A.; Pinnau, Ingo; Reinhard, Martin; Leckie, James O.

    2010-01-01

    Achieving a better understanding of transport and rejection mechanisms in RO and NF membranes requires more detailed information of the nanostructure of polyamide thin films. This study reports on two novel transmission electron microscopy (TEM) techniques for characterizing polyamide nanostructure. The first technique produces cross-sectional images of isolated polyamide thin films by removing the polysulfone support from regular TEM cross-sections. In the second technique called " projected area" TEM (PA-TEM), isolated polyamide thin films are placed with their surface perpendicular to the electron beam. The resulting images capture the thickness, morphology and mass density of the entire thin film. In combination, these new techniques provide information on polyamide nanostructure that is not evident using conventional methods. For the commercial RO membrane ESPA3, the cross-sectional view of the isolated polyamide thin film shows a 30-60. nm thick base of nodular polyamide (presumably the separation barrier) that forms a relatively smooth interface with the polysulfone support. Above this, a more open structure of loose polyamide extends outward giving rise to the ridge-and-valley surface structure. In PA-TEM images, the ridges and valleys correspond to the dark and bright regions, respectively; the polyamide nodular base appears as round features forming an irregular honeycomb pattern throughout the images. Membrane cross-sections were prepared with a simple resin embedding protocol using the acrylic resin LR White. The protocol did not require dehydration steps, and was applicable to both dry and wet membrane samples. Artifacts that may be produced during sample preparation were also documented. © 2010 Elsevier B.V.

  12. Characterization of isolated polyamide thin films of RO and NF membranes using novel TEM techniques

    KAUST Repository

    Pacheco, Federico A.

    2010-08-15

    Achieving a better understanding of transport and rejection mechanisms in RO and NF membranes requires more detailed information of the nanostructure of polyamide thin films. This study reports on two novel transmission electron microscopy (TEM) techniques for characterizing polyamide nanostructure. The first technique produces cross-sectional images of isolated polyamide thin films by removing the polysulfone support from regular TEM cross-sections. In the second technique called " projected area" TEM (PA-TEM), isolated polyamide thin films are placed with their surface perpendicular to the electron beam. The resulting images capture the thickness, morphology and mass density of the entire thin film. In combination, these new techniques provide information on polyamide nanostructure that is not evident using conventional methods. For the commercial RO membrane ESPA3, the cross-sectional view of the isolated polyamide thin film shows a 30-60. nm thick base of nodular polyamide (presumably the separation barrier) that forms a relatively smooth interface with the polysulfone support. Above this, a more open structure of loose polyamide extends outward giving rise to the ridge-and-valley surface structure. In PA-TEM images, the ridges and valleys correspond to the dark and bright regions, respectively; the polyamide nodular base appears as round features forming an irregular honeycomb pattern throughout the images. Membrane cross-sections were prepared with a simple resin embedding protocol using the acrylic resin LR White. The protocol did not require dehydration steps, and was applicable to both dry and wet membrane samples. Artifacts that may be produced during sample preparation were also documented. © 2010 Elsevier B.V.

  13. Synthesis of nanosilver on polyamide fabric using silver/ammonia complex

    Energy Technology Data Exchange (ETDEWEB)

    Montazer, Majid, E-mail: tex5mm@aut.ac.ir [Textile Department, Functional Fibrous Structures and Environmental Enhancement (FFSEE), Amirkabir University of Technology, Hafez Avenue, Tehran (Iran, Islamic Republic of); Shamei, Ali; Alimohammadi, Farbod [Young Researchers Club, Tehran South Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2014-05-01

    In this paper, a novel synthesis method for nanosilver has been introduced on or within the polymeric chains of polyamide 6 fabric by using silver/ammonia complex [Ag(NH{sub 3}){sub 2}]{sup +}. The silver complex was reduced directly by functional groups of polyamide chains without using any additional chemical reducing agents. The polyamide fabric was also stabilized with formation of new linkages between the polymeric chains of the nylon fabric through silver nanoparticle synthesis. The presence of nanosilver on the fabric was confirmed by UV–vis spectra, EDX patterns and XRD patterns. In addition, X-ray photoelectron spectroscopy (XPS) was utilized to identify the chemical state of silver in a range of silver oxide and silver metal. The SEM images confirmed the presence of nanosilver on the polyamide within the size of 20 and 150 nm. Excellent antibacterial properties were achieved with the treated fabrics against Staphylococcus aureus and Escherichia coli. Further, the antibacterial properties of the polyamide fabric treated with 35 mg/L silver/ammonia were durable against washing as they only decreased to 98.6% after 20 washes. In addition, some other properties of the treated fabrics including color changes, dimensional stability, water droplet adsorption, and reflectance spectrum are reported and thoroughly discussed. - Highlights: • Novel in situ synthesis of nanosilver on polyamide 6 • Synthesis of nanosilver without using external stabilizing and reducing agent • Synthesis of nanosilver particles within molecular chains of polyamide 6 • Producing antibacterial polyamide 6 using 35 mg/L Ag/ammonia complex • Obtaining durable antibacterial properties on polyamide 6 by this method.

  14. Synthesis of nanosilver on polyamide fabric using silver/ammonia complex

    International Nuclear Information System (INIS)

    Montazer, Majid; Shamei, Ali; Alimohammadi, Farbod

    2014-01-01

    In this paper, a novel synthesis method for nanosilver has been introduced on or within the polymeric chains of polyamide 6 fabric by using silver/ammonia complex [Ag(NH 3 ) 2 ] + . The silver complex was reduced directly by functional groups of polyamide chains without using any additional chemical reducing agents. The polyamide fabric was also stabilized with formation of new linkages between the polymeric chains of the nylon fabric through silver nanoparticle synthesis. The presence of nanosilver on the fabric was confirmed by UV–vis spectra, EDX patterns and XRD patterns. In addition, X-ray photoelectron spectroscopy (XPS) was utilized to identify the chemical state of silver in a range of silver oxide and silver metal. The SEM images confirmed the presence of nanosilver on the polyamide within the size of 20 and 150 nm. Excellent antibacterial properties were achieved with the treated fabrics against Staphylococcus aureus and Escherichia coli. Further, the antibacterial properties of the polyamide fabric treated with 35 mg/L silver/ammonia were durable against washing as they only decreased to 98.6% after 20 washes. In addition, some other properties of the treated fabrics including color changes, dimensional stability, water droplet adsorption, and reflectance spectrum are reported and thoroughly discussed. - Highlights: • Novel in situ synthesis of nanosilver on polyamide 6 • Synthesis of nanosilver without using external stabilizing and reducing agent • Synthesis of nanosilver particles within molecular chains of polyamide 6 • Producing antibacterial polyamide 6 using 35 mg/L Ag/ammonia complex • Obtaining durable antibacterial properties on polyamide 6 by this method

  15. Novel bio-composite of hydroxyapatite reinforced polyamide and polyethylene: Composition and properties

    International Nuclear Information System (INIS)

    Zuo Yi; Li Yubao; Li Jidong; Zhang Xiang; Liao Hongbing; Wang Yuanyuan; Yang Weihu

    2007-01-01

    A new bio-composite of hydroxyapatite reinforced polyamide 66 and high density polyethylene was prepared using melt mixing in a co-rotation twin screw extruder. Two series of composites with different composition were investigated using scanning electronic microscopy, mechanical testing, water absorption and infrared spectrometer. The results showed that the change of composition influenced significantly the properties of the composites by different mechanism. Polyethylene mixing with polyamide matrix induced different microstructure and adjusted water absorption and manufacturability. Hydrogen bonding between hydroxyapatite and the polar groups of polyamide improved the adhesion of interface

  16. Processing and properties of pressable ceramic with non-uniform reinforcement for selective-toughening

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Wei [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); School of Dentistry, The University of Western Australia, WA 6009 (Australia); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China); Hu, Xiaozhi, E-mail: xiao.zhi.hu@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Ichim, Paul [School of Dentistry, The University of Western Australia, WA 6009 (Australia); Sun, Xudong [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China)

    2012-12-15

    Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic-matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic-matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.

  17. Processing and properties of pressable ceramic with non-uniform reinforcement for selective-toughening

    International Nuclear Information System (INIS)

    Yi, Wei; Hu, Xiaozhi; Ichim, Paul; Sun, Xudong

    2012-01-01

    Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic–matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic–matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.

  18. Thermally reversible rubber-toughened thermoset networks via Diels-Alder chemistry

    NARCIS (Netherlands)

    Araya-Hermosilla, R.; Fortunato, G.; Pucci, A.; Raffa, P.; Polgar, L.; Broekhuis, A. A.; Pourhossein, P.; Lima, G. M. R.; Beljaars, M.; Picchioni, F.

    In this work we present a reversible and toughened thermoset system based on the covalent incorporation of a furane functionalized ethylene-propylene rubber (EPM-Fu) into a thermoset furane functionalized polyketone (PK-Fu) via Diels-Alder (DA) reversible cross-linking with bismaleimide (b-MA).

  19. Ultrathin Polyamide Membranes Fabricated from Free-Standing Interfacial Polymerization: Synthesis, Modifications, and Post-treatment

    KAUST Repository

    Cui, Yue; Liu, Xiang-Yang; Chung, Neal Tai-Shung

    2016-01-01

    ) membranes. The polyamide selective layer usually possesses a high selectivity and permeability, making it the heart of this membrane technology. To further improve and understand its formation, with entirely excluding the effect of substrate, an ultrathin

  20. Free volume sizes in intercalated polyamide 6/clay nanocomposites

    DEFF Research Database (Denmark)

    Wiinberg, P.; Eldrup, Morten Mostgaard; Pedersen, N.J.

    2005-01-01

    The effect of incorporating modified clay into a polyamide 6 (PA6) matrix, on the free volume cavity sizes and the thermal and viscoelastic properties of the resulting nanocomposite, was studied with positron annihilation lifetime spectroscopy, differential scanning calorimetry and dynamic...... response of PA6/clay nanocomposites, as compared to unfilled PA6, pointed towards a changed mobility in the non-crystalline regions. At high concentrations of clay (> 19 wt%) an increase of the free volume cavity diameter was observed, indicating a lower chain packing efficiency in the PA6/clay...... nanocomposites. The increased free volume sizes were present both above and below the glass transition temperature of PA6. (c) 2005 Elsevier Ltd. All rights reserved....

  1. Stiffening mechanisms in amorphous polyamide bio-nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Focke, Walter W. [Institute of Applied Materials, Department of Chemical Engineering, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria (South Africa); Macheca, Afonso D. [Institute of Applied Materials, Department of Chemical Engineering, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria (South Africa); Department of Chemical Engineering, Eduardo Mondlane University, P.O. Box 257, Maputo (Mozambique); Benhamida, Aida; Kaci, Mustapha [Laboratoire des Matériaux Polymères Avancés (LMPA), Université de Bejaia 06000 (Algeria)

    2016-05-18

    Dimer fatty acid polyamide nanocomposites based on flake- or needle-shaped nanoparticles were prepared via melt compounding. Transmission electron microscopy showed the presence of both individually dispersed particles and particle agglomerates in the polymer matrix. Dynamic mechanical analysis suggests that three stiffening mechanisms were operating. The reinforcing effect of the high stiffness inorganic filler particles is the primary contributor. Together with the chain confinement effect, that expresses itself in an apparent increase in the glass transition temperature, this provided an adequate rationalization of the stiffness variation below Tg. However, an additional stiffening effect is indicated at temperatures above Tg. The mechanism may involve dynamic network formation based on fluctuating hydrogen bonding interactions between the polymer chains and the filler particles.

  2. Processing and Mechanical Properties of Macro Polyamide Fiber Reinforced Concrete.

    Science.gov (United States)

    Jeon, Joong Kyu; Kim, WooSeok; Jeon, Chan Ki; Kim, Jin Cheol

    2014-11-26

    This study developed a macro-sized polyamide (PA) fiber for concrete reinforcement and investigated the influence of the PA fiber on flexural responses in accordance with ASTM standards. PA fibers are advantageous compared to steel fibers that are corrosive and gravitated. The macro-sized PA fiber significantly improved concrete ductility and toughness. Unlike steel fibers, the PA fibers produced two peak bending strengths. The first-peaks occurred near 0.005 mm of deflection and decreased up to 0.5 mm of deflection. Then the bending strength increased up to second-peaks until the deflections reached between 1.0 and 1.5 mm. The averaged flexural responses revealed that PA fiber content did not significantly influence flexural responses before L /600, but had significant influence thereafter. Toughness performance levels were also determined, and the results indicated more than Level II at L /600 and Level IV at others.

  3. Strain rate dependency of laser sintered polyamide 12

    Directory of Open Access Journals (Sweden)

    Cook J.E.T.

    2015-01-01

    Full Text Available Parts processed by Additive Manufacturing can now be found across a wide range of applications, such as those in the aerospace and automotive industry in which the mechanical response must be optimised. Many of these applications are subjected to high rate or impact loading, yet it is believed that there is no prior research on the strain rate dependence in these materials. This research investigates the effect of strain rate and laser energy density on laser sintered polyamide 12. In the study presented here, parts produced using four different laser sintered energy densities were exposed to uniaxial compression tests at strain rates ranging from 10−3 to 10+3 s−1 at room temperature, and the dependence on these parameters is presented.

  4. Research on mechanical properties of carbon fiber /polyamide reinforced PP composites

    Science.gov (United States)

    Chen, Xinghui; Yu, Qiang; Liu, Lixia; Ji, Wenhua; Yang, Li; Fan, Dongli

    2017-10-01

    The polyamide composites reinforced by carbon fiber/polypropylene are produced by injection molding processing. The flow abilities and mechanical properties of the CF/PA/PP composite materials are studied by the fusion index instrument and the universal testing machine. The results show that with the content of carbon fiber/polyamide increase, the impact breaking strength and the tensile property of the composite materials increase, which is instructive to the actual injection production of polypropylene products.

  5. Ultrathin Polyamide Membranes Fabricated from Free-Standing Interfacial Polymerization: Synthesis, Modifications, and Post-treatment

    KAUST Repository

    Cui, Yue

    2016-12-21

    The thin film composite (TFC) membrane synthesized via interfacial polymerization is the workhorse of the prevalent membrane technologies such as nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), and pressure retarded osmosis (PRO) membranes. The polyamide selective layer usually possesses a high selectivity and permeability, making it the heart of this membrane technology. To further improve and understand its formation, with entirely excluding the effect of substrate, an ultrathin membrane which consists of only the polyamide selective layer has been fabricated via free-standing interfacial polymerization between M-phenylenediamine (MPD) and trimesoyl chloride (TMC) in this study. The influences of monomer concentration on polyamide layer formation is first examined. Different from previous studies which indicated that the variation of MPD concentration might affect the polyamide layer formation even when in excess, the MPD concentration when in excess does not affect membrane properties significantly, while increasing the TMC concentration gradually densifies the polyamide layer and enhances its transport resistance. Adding lithium bromide (LiBr) and sodium dodecyl sulfate (SDS) in MPD solutions is found to facilitate the reaction between the two phases and result in a significant improvement in water permeability. However, a high amount of additives leads to an augmentation in transport resistance. The N,N-dimethylformamide (DMF) treatment on the polyamide membrane shows pronounced improvements on water flux under FO tests and water permeability under RO tests without compromising reverse salt flux and salt rejection because the dense polyamide core stays intact. This study may offer a different perspective on membrane formation and intrinsic properties of the polyamide selective layer and provide useful insights for the development of next-generation TFC membranes.

  6. The Effect of Silane Coupling Agents on a Composite Polyamide-6/Talc

    Directory of Open Access Journals (Sweden)

    H. Wiebeck

    1998-12-01

    Full Text Available This paper evaluates the effect of the addition of silane agents on the mechanical properties (tensile strength, hardness and flexibility of the composite polyamide-6/talc. For this purpose, 30% and 40% of a talc with and without the addition of silane agents were incorporated into polyamide-6. Three kinds of silane agents were used, resulting in nine formulations. Comparing the experimental results, it is concluded that the silane agents improve the mechanical properties of the composite material.

  7. 3D visualization of the internal nanostructure of polyamide thin films in RO membranes

    KAUST Repository

    Pacheco Oreamuno, Federico

    2015-11-02

    The front and back surfaces of fully aromatic polyamide thin films isolated from reverse osmosis (RO) membranes were characterized by TEM, SEM and AFM. The front surfaces were relatively rough showing polyamide protuberances of different sizes and shapes; the back surfaces were all consistently smoother with very similar granular textures formed by polyamide nodules of 20–50 nm. Occasional pore openings of approximately the same size as the nodules were observed on the back surfaces. Because traditional microscopic imaging techniques provide limited information about the internal morphology of the thin films, TEM tomography was used to create detailed 3D visualizations that allowed the examination of any section of the thin film volume. These tomograms confirmed the existence of numerous voids within the thin films and revealed structural characteristics that support the water permeance difference between brackish water (BWRO) and seawater (SWRO) RO membranes. Consistent with a higher water permeance, the thin film of the BWRO membrane ESPA3 contained relatively more voids and thinner sections of polyamide than the SWRO membrane SWC3. According to the tomograms, most voids originate near the back surface and many extend all the way to the front surface shaping the polyamide protuberances. Although it is possible for the internal voids to be connected to the outside through the pore openings on the back surface, it was verified that some of these voids comprise nanobubbles that are completely encapsulated by polyamide. TEM tomography is a powerful technique for investigating the internal nanostructure of polyamide thin films. A comprehensive knowledge of the nanostructural distribution of voids and polyamide sections within the thin film may lead to a better understanding of mass transport and rejection mechanisms in RO membranes.

  8. 3D visualization of the internal nanostructure of polyamide thin films in RO membranes

    KAUST Repository

    Pacheco Oreamuno, Federico; Sougrat, Rachid; Reinhard, Martin; Leckie, James O.; Pinnau, Ingo

    2015-01-01

    The front and back surfaces of fully aromatic polyamide thin films isolated from reverse osmosis (RO) membranes were characterized by TEM, SEM and AFM. The front surfaces were relatively rough showing polyamide protuberances of different sizes and shapes; the back surfaces were all consistently smoother with very similar granular textures formed by polyamide nodules of 20–50 nm. Occasional pore openings of approximately the same size as the nodules were observed on the back surfaces. Because traditional microscopic imaging techniques provide limited information about the internal morphology of the thin films, TEM tomography was used to create detailed 3D visualizations that allowed the examination of any section of the thin film volume. These tomograms confirmed the existence of numerous voids within the thin films and revealed structural characteristics that support the water permeance difference between brackish water (BWRO) and seawater (SWRO) RO membranes. Consistent with a higher water permeance, the thin film of the BWRO membrane ESPA3 contained relatively more voids and thinner sections of polyamide than the SWRO membrane SWC3. According to the tomograms, most voids originate near the back surface and many extend all the way to the front surface shaping the polyamide protuberances. Although it is possible for the internal voids to be connected to the outside through the pore openings on the back surface, it was verified that some of these voids comprise nanobubbles that are completely encapsulated by polyamide. TEM tomography is a powerful technique for investigating the internal nanostructure of polyamide thin films. A comprehensive knowledge of the nanostructural distribution of voids and polyamide sections within the thin film may lead to a better understanding of mass transport and rejection mechanisms in RO membranes.

  9. Sequence-specific DNA alkylation by tandem Py-Im polyamide conjugates.

    Science.gov (United States)

    Taylor, Rhys Dylan; Kawamoto, Yusuke; Hashiya, Kaori; Bando, Toshikazu; Sugiyama, Hiroshi

    2014-09-01

    Tandem N-methylpyrrole-N-methylimidazole (Py-Im) polyamides with good sequence-specific DNA-alkylating activities have been designed and synthesized. Three alkylating tandem Py-Im polyamides with different linkers, which each contained the same moiety for the recognition of a 10 bp DNA sequence, were evaluated for their reactivity and selectivity by DNA alkylation, using high-resolution denaturing gel electrophoresis. All three conjugates displayed high reactivities for the target sequence. In particular, polyamide 1, which contained a β-alanine linker, displayed the most-selective sequence-specific alkylation towards the target 10 bp DNA sequence. The tandem Py-Im polyamide conjugates displayed greater sequence-specific DNA alkylation than conventional hairpin Py-Im polyamide conjugates (4 and 5). For further research, the design of tandem Py-Im polyamide conjugates could play an important role in targeting specific gene sequences. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Formation of high aspect ratio polyamide-6 nanofibers via electrically induced double layer during electrospinning

    International Nuclear Information System (INIS)

    Nirmala, R.; Nam, Ki Taek; Park, Soo-Jin; Shin, Yu-Shik; Navamathavan, R.; Kim, Hak Yong

    2010-01-01

    In the present study, the formation of high aspect ratio nanofibers in polyamide-6 was investigated as a function of applied voltage ranging from 15 to 25 kV using electrospinning technique. All other experimental parameters were kept constant. The electrospun polyamide-6 nanofibers were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF). FE-SEM images of polyamide-6 nanofibers showed that the diameter of the electrospun fiber was decreased with increasing applied voltage. At the critical applied voltage, the polymer solution was completely ionized to form the dense high aspect ratio nanofibers in between the main nanofibers. The diameter of the polyamide-6 nanofibers was observed to be in the range of 75-110 nm, whereas the high aspect ratio structures consisted of regularly distributed very fine nanofibers with diameters of about 9-28 nm. Trends in fiber diameter and diameter distribution were discussed for the high aspect ratio nanofibers. TEM results revealed that the formation of double layers in polyamide-6 nanofibers and then split-up into ultrafine fibers. The electrically induced double layer in combination with the polyelectrolytic nature of solution is proposed as the suitable mechanisms for the formation of high aspect ratio nanofibers in polyamide-6.

  11. Synthesis and characterizations of Pt nanorods on electrospun polyamide-6 nanofibers templates

    International Nuclear Information System (INIS)

    Nirmala, R.; Navamathavan, R.; Won, Jeong Jin; Jeon, Kyung Soo; Yousef, Ayman; Kim, Hak Yong

    2012-01-01

    Highlights: ► Electrospun polyamide-6 nanofibers were used as the templates for synthesis Pt nanorods. ► Polyamide-6 nanofibers surfaces were plasma treated to coat Pt. ► High quality Pt nanorods were obtained by calcinations process. ► Pt nanorods with a diameter of few hundred nanometers were obtained. ► Polyamide-6 nanofibers template based Pt nanorods synthesis are a feasible method. - Abstract: We report on the synthesis of platinum (Pt) nanorods by using ultrafine polyamide-6 nanofibers templates produced via electrospinning technique. These ultrafine polyamide-6 nanofibers can be utilized as the templates for growing Pt nanorods after modifying them optimally by plasma passivations. The morphological, structural, optical and electrical properties of the template assisted Pt nanorods were studied by field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), photoluminescence (PL) and current–voltage (I–V) characteristics. The ability to fabricate the ultrafine size controlled Pt nanorods on polyamide-6 templates with optimized growth parameters in real time can be utilized for the variety of technological applications. Therefore, it is possible to obtain high quality with size control Pt nanorods. Once obtaining the high quality metal nanorods on polymer templates, the same can be adapted for the electronic device fabrication.

  12. Toughness determination of zirconia toughened alumina ceramics from growth of indentation-induced cracks

    International Nuclear Information System (INIS)

    Basu, D.; Sarkar, B.K.

    1996-01-01

    Short surface cracks were generated by Vickers indentation on the polished surface of alumina and different zirconia toughened alumina (ZTA) specimens, and their morphology was studied by serial sectioning. These cracks were grown in three-point bend tests under stepwise loading, and variation of toughness with crack extension was plotted to graphically separate the contributions from residual stress intensity and applied stress intensity factors. The plateau toughness determined from the intercept height of the crack extension plots exhibited an upward trend with zirconia content up to 15 vol% ZrO 2 addition in the composition, which was proportional to the fraction of transformable tetragonal grains contributing to transformation toughening. copyright 1996 Materials Research Society

  13. Development of Polymer Blends in order to Toughening of Polymers: A review

    Directory of Open Access Journals (Sweden)

    Carlos Bruno Barreto Luna

    2015-05-01

    Full Text Available Polymers are materials of large use in the various sectors of the world economy. The use of polymeric materials in daily life, instead of the classic materials has increased in recent decades. However, for certain structural applications polymers need to get tougher. One of the principal toughening techniques based on physical mixture of two or more components, forming the so-called polymer blends. The addition of rubber or not vulcanized in polymer compositions is reported in the literature as a means of generating mixtures of easy processing, and economically advantageous to increase the toughness of the thermoplastic matrix of interest. Moreover, it can be an alternative for the recycling of waste tires and footwear coming from industries, as well reduce harmful effects on the environment. Therefore, the present study aims to present a review of the definitions, benefits, thermodynamic fundamentals and toughening polymers.

  14. Microstructural effects of ductile phase toughening of Nb-Nb silicide composites

    International Nuclear Information System (INIS)

    Lewandowski, J.J.; Dimiduk, D.; Kerr, W.; Menddiratta, M.G.

    1988-01-01

    In the Nb-Si system, the terminal Nb phase and Nb 5 Si 3 phase are virtually immiscible up to approximately 2033k. This system offers the potential of producing composites consisting of a ductile refractory metal phase and a strong intermetallic phase. In-situ composites containing different volume fractions of the ductile Nb phase were produced via vacuum arc-casting. Microhardness testing as well as smooth bend bar testing was conducted at temperatures ranging from 298k to 1673k in an attempt to determine microstructural effects on the yield strength and smooth bar fracture strength. Notched bend specimens were similarly tested to determine the effects of the ductile phase (i.e. Nb) on enhancing the notched bend toughness. It is shown that Nb phase often behaves in a ductile manner during testing, thereby toughening the in-situ composite. The mechanism of toughening appears to be due to crack bridging

  15. Transient subcritical crack-growth behavior in transformation-toughened ceramics

    International Nuclear Information System (INIS)

    Dauskardt, R.H.; Ritchie, R.O.; Carter, W.C.; Veirs, D.K.

    1990-01-01

    Transient subcritical crack-growth behavior following abrupt changes in the applied load are studied in transformation-toughened ceramics. A mechanics analysis is developed to model the transient nature of transformation shielding of the crack tip, K s , with subcritical crack extension following the applied load change. conditions for continued crack growth, crack growth followed by arrest, and no crack growth after the load change, are considered and related to the magnitude and sign of the applied load change and to materials properties such as the critical transformation stress. The analysis is found to provide similar trends in K s compared to values calculated from experimentally measured transformation zones in a transformation-toughened Mg-PSZ. In addition, accurate prediction of the post load-change transient crack-growth behavior is obtained using experimentally derived steady-state subcritical crack-growth relationships for cyclic fatigue in the same material

  16. Microcracking and mechanical properties of Hafnia-Zirconia toughened alumina composites

    International Nuclear Information System (INIS)

    Li, H.P.S.; Stevens, R.

    1995-01-01

    Despite the remarkably similar crystal structures and phase transformations of HfO 2 and ZrO 2 , the tetragonal to monoclinic transformation temperature for HfO 2 takes place six hundred degrees higher than that for ZrO 2 . This suggests the potential for HfO 2 as an engineering material for use at elevated temperatures (>700 C). Alloying HfO 2 with ZrO 2 has been suggested a feasible high-temperature toughening strategy for ZrO 2 -toughened ceramics. The role of ZrO 2 as a second phase toughening agent for ceramic composites has long been recognised and a considerable number of studies reported. In contrast, HfO 2 -toughened ceramics, have not been investigated in detail. This paper gives an account of composite ceramics consisting of an Al 2 O 3 matrix, mixed with unstabilised (Zr-Hf)O 2 inclusions containing volume fractions, of 0, 1, 5, 10, 15, and 25 vol. %, developed to investigate the effects of the second phase content on the microstructure and mechanical properties. A simple cubic packing model of microcracking, based on an ''end-point'' thermodynamic approach, is discussed with respect to microcrack extension for a critical volume fraction of second phase content. The results show an Al 2 O 3 matrix containing 5 vol. % of Hf 0.25 Zr 0.75 O 2 inclusions to give the optimum properties. Using the packing model, the critical volume fraction is predicted at 10 vol. %, which is in a good agreement with experimental results. (orig.)

  17. A novel hyper-viscoelastic model for consolidation of toughened prepregs under processing conditions

    OpenAIRE

    Belnoue, J.P.-H.; Nixon-Pearson, O.J.; Ivanov, D.; Hallett, S.R.

    2016-01-01

    The paper presents a new modelling concept for describing the compressibility of toughened uncured prepregs over a wide range of processing conditions (i.e. automatic fibre deposition, hot debulking and pre-curing consolidation). The primary challenge of the work is to simulate the material response due complex flow and deformation mechanisms. This generation of prepreg systems exhibits both percolation (bleeding) flow typical for conventional thermosets, where the pressure gradient causes re...

  18. Direct observation of toughening mechanisms in carbon nanotube ceramic matrix composites

    International Nuclear Information System (INIS)

    Xia, Z.; Riester, L.; Curtin, W.A.; Li, H.; Sheldon, B.W.; Liang, J.; Chang, B.; Xu, J.M.

    2004-01-01

    The excellent mechanical properties of carbon nanotubes (CNTS) are driving research into the creation of new strong, tough nanocomposite systems. Here, the first evidence of toughening mechanisms operating in carbon-nanotube-reinforced ceramic composites is presented. A highly ordered array of parallel multiwall CNTs in an alumina matrix was fabricated. Nanoindentation introduced controlled cracks and the damage was examined by scanning electron microscopy. These nanocomposites exhibit the three hallmarks of toughening found in micron-scale fiber composites: crack deflection at the CNT/matrix interface; crack bridging by CNTs; and CNT pullout on the fracture surfaces. Interface debonding and sliding can thus occur in materials with microstructures approaching the atomic scale. Furthermore, for certain geometries a new mechanism of nanotube collapse in 'shear bands' occurs, rather than crack formation, suggesting that these materials can have multiaxial damage tolerance. The quantitative indentation data and computational models are used to determine the multiwall CNT axial Young's modulus as 200-570 GPa, depending on the nanotube geometry and quality. Three-dimensional FEM analysis indicates that matrix residual stresses on the order of 300 MPa are sustained in these materials without spontaneous cracking, suggesting that residual stress can be used to engineer enhanced performance. These nanoscale ceramic composites thus have potential for toughening and damage tolerance at submicron scales, and so are excellent candidates for wear-resistant coatings

  19. Thermal shock behavior of toughened gadolinium zirconate/YSZ double-ceramic-layered thermal barrier coating

    International Nuclear Information System (INIS)

    Zhong, Xinghua; Zhao, Huayu; Zhou, Xiaming; Liu, Chenguang; Wang, Liang; Shao, Fang; Yang, Kai; Tao, Shunyan; Ding, Chuanxian

    2014-01-01

    Highlights: • Gd 2 Zr 2 O 7 /YSZ DCL thermal barrier coating was designed and fabricated. • The Gd 2 Zr 2 O 7 top ceramic layer was toughened by addition of nanostructured 3YSZ. • Remarkable improvement in thermal shock resistance of the DCL coating was achieved. - Abstract: Double-ceramic-layered (DCL) thermal barrier coating system comprising of toughened Gadolinium zirconate (Gd 2 Zr 2 O 7 , GZ) as the top ceramic layer and 4.5 mol% Y 2 O 3 partially-stabilized ZrO 2 (4.5YSZ) as the bottom ceramic layer was fabricated by plasma spraying and thermal shock behavior of the DCL coating was investigated. The GZ top ceramic layer was toughened by addition of nanostructured 3 mol% Y 2 O 3 partially-stabilized ZrO 2 (3YSZ) to improve fracture toughness of the matrix. The thermal shock resistance of the DCL coating was enhanced significantly compared to that of single-ceramic-layered (SCL) GZ-3YSZ composite coating, which is believed to be primarily attributed to the two factors: (i) the increase in fracture toughness of the top ceramic layer by incorporating nanostructured YSZ particles and (ii) the improvement in strain tolerance through the utilization of 4.5YSZ as the bottom ceramic layer. In addition, the failure mechanisms are mainly attributed to the still low fracture toughness of the top ceramic layer and oxidation of the bond-coat

  20. Learning from evolutionary optimisation: what are toughening mechanisms good for in dentine, a nonrepairing bone tissue?

    Science.gov (United States)

    Zaslansky, Paul; Currey, John D; Fleck, Claudia

    2016-09-12

    The main mass of material found in teeth is dentine, a bone-like tissue, riddled with micron-sized tubules and devoid of living cells. It provides support to the outer wear-resistant layer of enamel, and exhibits toughening mechanisms which contribute to crack resistance. And yet unlike most bone tissues, dentine does not remodel and consequently any accumulated damage does not 'self repair'. Because damage containment followed by tissue replacement is a prime reason for the crack-arresting microstructures found in most bones, the occurrence of toughening mechanisms without the biological capability to repair is puzzling. Here we consider the notion that dentine might be overdesigned for strength, because it has to compensate for the lack of cell-mediated healing mechanisms. Based on our own and on literature-reported observations, including quasistatic and fatigue properties, dentine design principles are discussed in light of the functional conditions under which teeth evolved. We conclude that dentine is only slightly overdesigned for everyday cyclic loading because usual mastication stresses may come close to its endurance strength. The in-built toughening mechanisms constitute an evolutionary benefit because they prevent catastrophic failure during rare overload events, which was probably very advantageous in our hunter gatherer ancestor times. From a bio-inspired perspective, understanding the extent of evolutionary overdesign might be useful for optimising biomimetic structures used for load bearing.

  1. Isocyanate toughening of pCBT/organoclay nanocomposites with exfoliated structure and enhanced mechanical properties

    Directory of Open Access Journals (Sweden)

    T. Abt

    2014-12-01

    Full Text Available Cyclic butylene terephthalate (CBT® is an interesting matrix material for the preparation of nanocomposites due to its very low, water-like melt viscosity which favours clay exfoliation. Nevertheless, polymerized CBT (pCBT is inherently brittle. This paper reports the preparation of isocyanate-toughened nanocomposites made from CBT and organo-modified montmorillonite. The role of the organoclay as reinforcement and the polymeric isocyanate (PMDI as toughening agent on the properties of pCBT was studied. The organoclay increased the stiffness and strength by up to 20% whereas the PMDI improved the deformation behaviour. However, the PMDI did not affect the degree of clay dispersion or exfoliation and flocculated-intercalated structures were observed. The compatibility between the pCBT matrix and clay was further increased by preparing PMDI-tethered intercalated organoclay. The modified organoclay then exfoliated during ring-opening polymerization and yielded true pCBT/clay nanocomposites. This work demonstrates that reactive chain extension of CBT with a polyfunctional isocyanate is an effective method to obtain toughened pCBT nanocomposites. Moreover, isocyanates can enhance the compatibility between pCBT and nanofiller as well as the degree of exfoliation.

  2. Lecithin blended polyamide-6 high aspect ratio nanofiber scaffolds via electrospinning for human osteoblast cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Nirmala, R. [Bio-nano System Engineering, College of Engineering, Chonbuk National University, Jeonju, 561 756 (Korea, Republic of); Park, Hye-Min [Department of Pharmacology and Toxicology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561 756 (Korea, Republic of); Navamathavan, R. [School of Advanced Materials Engineering, Chonbuk National University, Jeonju 561 756 (Korea, Republic of); Kang, Hyung-Sub [Department of Pharmacology and Toxicology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561 756 (Korea, Republic of); El-Newehy, Mohamed H. [Petrochemical Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Kim, Hak Yong, E-mail: khy@jbnu.ac.kr [Petrochemical Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Center for Healthcare Technology and Development, Chonbuk National University, Jeonju, 561 756 (Korea, Republic of)

    2011-03-12

    In this study, we focused on the preparation and characterization of lecithin blended polyamide-6 nanofibers via an electrospinning process for human osteoblastic (HOB) cell culture applications. The morphological, structural characterizations and thermal properties of polyamide-6/lecithin nanofibers were determined by using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). SEM images revealed that the nanofibers were well-oriented with good incorporation of lecithin. FT-IR results indicated the presence of amino groups of lecithin in the blended nanofibers. TGA analysis revealed that the onset degradation temperature decreased with increasing lecithin content in the blended nanofibers. The morphological features of cells attached on polyamide-6/lecithin nanofibers were confirmed by SEM. The adhesion, viability and proliferation properties of osteoblast cells on the polyamide-6/lecithin blended nanofibers were analyzed by in vitro cell compatibility test. This study demonstrated the non-cytotoxic behavior of electrospun polyamide-6/lecithin nanofibers for the osteoblast cell culture.

  3. Lecithin blended polyamide-6 high aspect ratio nanofiber scaffolds via electrospinning for human osteoblast cell culture

    International Nuclear Information System (INIS)

    Nirmala, R.; Park, Hye-Min; Navamathavan, R.; Kang, Hyung-Sub; El-Newehy, Mohamed H.; Kim, Hak Yong

    2011-01-01

    In this study, we focused on the preparation and characterization of lecithin blended polyamide-6 nanofibers via an electrospinning process for human osteoblastic (HOB) cell culture applications. The morphological, structural characterizations and thermal properties of polyamide-6/lecithin nanofibers were determined by using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). SEM images revealed that the nanofibers were well-oriented with good incorporation of lecithin. FT-IR results indicated the presence of amino groups of lecithin in the blended nanofibers. TGA analysis revealed that the onset degradation temperature decreased with increasing lecithin content in the blended nanofibers. The morphological features of cells attached on polyamide-6/lecithin nanofibers were confirmed by SEM. The adhesion, viability and proliferation properties of osteoblast cells on the polyamide-6/lecithin blended nanofibers were analyzed by in vitro cell compatibility test. This study demonstrated the non-cytotoxic behavior of electrospun polyamide-6/lecithin nanofibers for the osteoblast cell culture.

  4. Sugar-Based Polyamides: Self-Organization in Strong Polar Organic Solvents.

    Science.gov (United States)

    Rosu, Cornelia; Russo, Paul S; Daly, William H; Cueto, Rafael; Pople, John A; Laine, Roger A; Negulescu, Ioan I

    2015-09-14

    Periodic patterns resembling spirals were observed to form spontaneously upon unassisted cooling of d-glucaric acid- and d-galactaric acid-based polyamide solutions in N-methyl-N-morpholine oxide (NMMO) monohydrate. Similar observations were made in d-galactaric acid-based polyamide/ionic liquid (IL) solutions. The morphologies were investigated by optical, polarized light and confocal microscopy assays to reveal pattern details. Differential scanning calorimetry was used to monitor solution thermal behavior. Small- and wide-angle X-ray scattering data reflected the complex and heterogeneous nature of the self-organized patterns. Factors such as concentration and temperature were found to influence spiral dimensions and geometry. The distance between rings followed a first-order exponential decay as a function of polymer concentration. Fourier-Transform Infrared Microspectroscopy analysis of spirals pointed to H-bonding between the solvent and the pendant hydroxyl groups of the glucose units from the polymer backbone. Tests on self-organization into spirals of ketal-protected d-galactaric acid polyamides in NMMO monohydrate confirmed the importance of the monosaccharide's pendant free hydroxyl groups on the formation of these patterns. Rheology performed on d-galactaric-based polyamides at high concentration in NMMO monohydrate solution revealed the optimum conditions necessary to process these materials as fibers by spinning. The self-organization of these sugar-based polyamides mimics certain biological materials.

  5. Synthesis of nanosilver on polyamide fabric using silver/ammonia complex.

    Science.gov (United States)

    Montazer, Majid; Shamei, Ali; Alimohammadi, Farbod

    2014-05-01

    In this paper, a novel synthesis method for nanosilver has been introduced on or within the polymeric chains of polyamide 6 fabric by using silver/ammonia complex [Ag(NH3)2](+). The silver complex was reduced directly by functional groups of polyamide chains without using any additional chemical reducing agents. The polyamide fabric was also stabilized with formation of new linkages between the polymeric chains of the nylon fabric through silver nanoparticle synthesis. The presence of nanosilver on the fabric was confirmed by UV-vis spectra, EDX patterns and XRD patterns. In addition, X-ray photoelectron spectroscopy (XPS) was utilized to identify the chemical state of silver in a range of silver oxide and silver metal. The SEM images confirmed the presence of nanosilver on the polyamide within the size of 20 and 150 nm. Excellent antibacterial properties were achieved with the treated fabrics against Staphylococcus aureus and Escherichia coli. Further, the antibacterial properties of the polyamide fabric treated with 35 mg/L silver/ammonia were durable against washing as they only decreased to 98.6% after 20 washes. In addition, some other properties of the treated fabrics including color changes, dimensional stability, water droplet adsorption, and reflectance spectrum are reported and thoroughly discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Tribological properties of nanosized calcium carbonate filled polyamide 66 nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Itagaki, Kaito [Department of Mechanical Engineering, Graduate School of Engineering, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 Japan (Japan); Nishitani, Yosuke [Department of Mechanical Engineering, Faculty of Engineering, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo, 192-0015 Japan (Japan); Kitano, Takeshi [Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, T.G.M. 275, Zlin, 767 72 Czech Republic (Czech Republic); Eguchi, Kenichiro [Shiraishi Central Laboratories, 4-78 Motohama,Amagasaki,Hyogo,660-0085 Japan (Japan)

    2016-03-09

    For the purpose of developing high performance tribomaterials for mechanical sliding parts such as gears, bearings and so on, nanosized calcium carbonate (nano-CaCO{sub 3}) filled polyamide 66 (PA66) nanocomposites were investigated. The nano-CaCO{sub 3} was a kind of precipitated (colloid typed) CaCO{sub 3}, and its average particle size was 40, 80 and 150 nm. Surface treatment was performed by fatty acid on the nano-CaCO{sub 3} and its volume fraction in the nanocomposite was varied from 1 to 20vol.%. These nanocomposites were melt-mixed by a twin screw extruder and injection-molded. Tribological properties were measured by two types of sliding wear testers such as ring-on-plate type and ball-on-plate type one under dry condition. The counterface, worn surface and wear debris were observed by digital microscope and scanning electron microscope. It was found that the nano-CaCO{sub 3} has a good effect on the tribological properties, although the effect on the frictional coefficient and specific wear rate is differed by the volume fraction and the type of sliding wear modes. This is attributed to the change of wear mechanisms, which is the change of form of the transfer films on the counterface and the size of wear debris. It follows from these results that PA66/nano-CaCO{sub 3} nanocomposites may be possible to be the high performance tribomaterials.

  7. Ionic Liquids Incorporating Polyamide 6: Miscibility and Physical Properties

    Directory of Open Access Journals (Sweden)

    Xin Zheng

    2018-05-01

    Full Text Available The effects of 1-vinyl-3-butyl imidazole chloride (VBIM on the structure and properties of Polyamide 6 (PA6 were investigated systematically. It was found that PA6/VBIM blends were homogeneous without phase separation. The glass transition temperature (Tg of PA6 increased with small VBIM loadings followed by the decreasing in Tg with further increasing the amount of VBIM. The crystallization temperature decreased with the addition of VBIM because of the strong interactions between VBIM and the PA6 matrix, as well as the dilution effect when large amounts of VBIM was introduced to the matrix. According to rheological testing, small amounts of VBIM enhanced the storage modulus and melt viscosity of PA6. Tensile tests also show an increase in strength and modulus at relatively low loadings of VBIM. The strength of PA6 with only 1 wt % VBIM improved by 108% compared to that of neat PA6. Fourier transform infrared (FTIR investigations revealed that the ions of VBIM preferred to form hydrogen bonds with amide groups in PA6. Therefore, VBIM acts as physical connection point for the neighboring PA6 molecular chains. The specific interactions between VBIM and PA6 account not only for the enhanced melt viscosity of PA6, but also for the improved mechanical properties. Moreover, outstanding antistatic property was also observed. The surface resistivity of the sample with 1 wt % VBIM was 1.50 × 1010 Ω/sq, which means good electric dissipation property.

  8. Flame retardancy of highly filled polyamide 6/clay nanocomposites

    International Nuclear Information System (INIS)

    Dasari, Aravind; Yu Zhongzhen; Mai Yiuwing; Liu Songlin

    2007-01-01

    To obtain an in-depth physical knowledge of the protective barrier stability and uniformity under fire conditions, we prepared highly filled polyamide 6/organoclay nanocomposites and characterized their thermal and flammability properties. The objectives were to identify a critical composition that is needed to form a stable char with no apertures or cracks and to gain a thorough understanding of the mechanisms of flame retardancy. It was shown that there is no need for higher percentages of clay and even smaller amounts of clay (<10 wt%) should be enough to achieve good fire performance. Factors such as incoherency, poor stability and non-uniformity of the char or the presence of large cracks and formation of island-like structures were insignificant in slowing down the heat release and mass loss rates. Nevertheless, there was no stage during the flammability test where the fire completely extinguished even when the protective layer was stable and free from major cracks/apertures. Based on these results, new insights and approaches to process better flame retardant polymer nanocomposites are discussed

  9. Hybrid membranes of polyamide applied in treatment of waste water

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Keila Machado de; Araujo, Edcleide Maria; Lira, Helio de Lucena, E-mail: keilamachadodemedeiros@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais; Lima, Diego de Farias; Lima, Carlos Antonio Pereira de [Universidade Estadual da Paraiba (UEPB), Campina Grande, PB (Brazil). Departamento de Engenharia Sanitaria e Ambiental

    2017-03-15

    In this work, it was prepared hybrid membranes of polyamide6 (PA6) with montmorillonite (MMT) and porogenic agent (CaCl{sub 2} ). The hybrid membranes with CaCl{sub 2} were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), porosimetry by mercury intrusion (PMI), flux measurements and rejection. By means of X-ray diffraction, it was revealed that the hybrid membranes with CaCl{sub 2} have an exfoliated and/or partially exfoliated structure. For FTIR and DSC of hybrid membranes with CaCl{sub 2} , it was found that the spectra and the crystalline melting temperature remained virtually unchanged compared to PA6 membrane. From the SEM images, it was observed that the addition of the MMT and the CaCl{sub 2} in the membrane of PA6 caused an increase in the amount of pores the surface and cross section of these membranes. By PMI, it was observed that the presence of MMT and CaCl{sub 2} in the membrane caused an increase in the average diameters of pores. The water-oil separation tests, indicated a significant reduction of oil in the permeate, allowing treatment of wastewater contaminated with oil. (author)

  10. Hybrid membranes of polyamide applied in treatment of waste water

    International Nuclear Information System (INIS)

    Medeiros, Keila Machado de; Araujo, Edcleide Maria; Lira, Helio de Lucena; Lima, Diego de Farias; Lima, Carlos Antonio Pereira de

    2017-01-01

    In this work, it was prepared hybrid membranes of polyamide6 (PA6) with montmorillonite (MMT) and porogenic agent (CaCl 2 ). The hybrid membranes with CaCl 2 were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), porosimetry by mercury intrusion (PMI), flux measurements and rejection. By means of X-ray diffraction, it was revealed that the hybrid membranes with CaCl 2 have an exfoliated and/or partially exfoliated structure. For FTIR and DSC of hybrid membranes with CaCl 2 , it was found that the spectra and the crystalline melting temperature remained virtually unchanged compared to PA6 membrane. From the SEM images, it was observed that the addition of the MMT and the CaCl 2 in the membrane of PA6 caused an increase in the amount of pores the surface and cross section of these membranes. By PMI, it was observed that the presence of MMT and CaCl 2 in the membrane caused an increase in the average diameters of pores. The water-oil separation tests, indicated a significant reduction of oil in the permeate, allowing treatment of wastewater contaminated with oil. (author)

  11. Improved Mechanical Properties of Compatibilized Polypropylene/Polyamide-12 Blends

    Directory of Open Access Journals (Sweden)

    Nora Aranburu

    2015-01-01

    Full Text Available Compatibilized blends of polypropylene (PP and polyamide-12 (PA12 as a second component were obtained by direct injection molding having first added 20% maleic anhydride-modified copolymer (PP-g-MA to the PP, which produced partially grafted PP (gPP. A nucleating effect of the PA12 took place on the cooling crystallization of the gPP, and a second crystallization peak of the gPP appeared in the PA12-rich blends, indicating changes in the crystalline morphology. There was a slight drop in the PA12 crystallinity of the compatible blends, whereas the crystallinity of the gPP increased significantly in the PA12-rich blends. The overall reduction in the dispersed phase particle size together with the clear increase in ductility when gPP was used instead of PP proved that compatibilization occurred. Young’s modulus of the blends showed synergistic behavior. This is proposed to be both due to a change in the crystalline morphology of the blends on the one hand and, on the other, in the PA12-rich blends, to the clear increase in the crystallinity of the gPP phase, which may, in turn, have been responsible for the increase in its continuity and its contribution to the modulus.

  12. Fluorescent detection of C-reactive protein using polyamide beads

    Science.gov (United States)

    Jagadeesh, Shreesha; Chen, Lu; Aitchison, Stewart

    2016-03-01

    Bacterial infection causes Sepsis which is one of the leading cause of mortality in hospitals. This infection can be quantified from blood plasma using C - reactive protein (CRP). A quick diagnosis at the patient's location through Point-of- Care (POC) testing could give doctors the confidence to prescribe antibiotics. In this paper, the development and testing of a bead-based procedure for CRP quantification is described. The size of the beads enable them to be trapped in wells without the need for magnetic methods of immobilization. Large (1.5 mm diameter) Polyamide nylon beads were used as the substrate for capturing CRP from pure analyte samples. The beads captured CRP either directly through adsorption or indirectly by having specific capture antibodies on their surface. Both methods used fluorescent imaging techniques to quantify the protein. The amount of CRP needed to give a sufficient fluorescent signal through direct capture method was found suitable for identifying bacterial causes of infection. Similarly, viral infections could be quantified by the more sensitive indirect capture method. This bead-based assay can be potentially integrated as a disposable cartridge in a POC device due to its passive nature and the small quantities needed.

  13. Antibacterial Properties of Functional Polyamide 6.6

    Directory of Open Access Journals (Sweden)

    El Bouchti Mehdi

    2014-06-01

    Full Text Available Polyamide 6.6 multifilaments are grafted with the monomer N-allyliminodiacetic acid for the purpose of removal of some heavy metal ions from their aqueous solutions by forming its metal chelate especially with Ag+ ion. Such a fibrous chelate-forming resin has been used with success due to its large surface area, which contains an important metal chelate-forming functional group, where metal ions are adsorbed or desorbed on its surface, and therefore having an improved adsorption and desorption capability. In previous work, chelate-forming fibre was characterised by ICP-AES analysis according to the digestion method by microwave. The antibacterial activity of the prepared fibre is investigated with Escherichia coli bacteria as reference, according to the zone of inhibition method in agar medium. The material used as reference without metal does not present any effect on E. coli. However, the chelateforming fibres with Ag+ have a strong bactericidal effect, even with a low concentration of silver ions. These modified materials can be used as highly effective bactericidal composites that may be used in future applications for the production of antimicrobial textiles, papers or polymer materials

  14. Structural comparison of nanocomposites membranes of polyamide 6 and polyamide 6.6 with a regional clay; Comparacao estrutural de membranas de nanocompositos de poliamida 6 e poliamida 6.6 com uma argila regional

    Energy Technology Data Exchange (ETDEWEB)

    Leite, A M.D.; Medeiros, V N; Paz, R A; Araujo, E M; Lira, H.L., E-mail: amandamelissa.lins@yahoo.com.b [Universidade Federal de Campina Grande (UAEMa/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Ito, Edson N [Universidade Federal do Rio Grande do Norte (DEMat/UFRN), Natal, RN (Brazil). dept. de Engenharia de Materiais

    2010-07-01

    Polyamide membranes do not require wetting agents because they are hydrophilic membranes and show great interest in the separation of aqueous solutions. With this, there is the interest to produce membranes from nanocomposites (polyamide 6 and polyamide 6.6)/organoclay), using the technique of isothermal immersion-precipitation in a bath with distilled water. The objective of this work was to produce, characterize and compare nanocomposites of polyamide 6 and polyamide 6.6/organoclay for use in the preparation of membranes. The nanocomposites were produced with 3 wt% of clay organically modified by quaternary ammonium salt (Cetremide) and were characterized by XRD and TEM. The nanocomposites presented an exfoliated/partially exfoliated structure. The membranes were characterized by SEM and presented a dense layer (selective skin) and another layer with uniform pores distributed along the membrane. (author)

  15. Vibration electrospinning of Polyamide-66/Multiwall Carbon Nanotube Nanocomposite: introducing electrically conductive, ultraviolet blocking and antibacterial properties

    Directory of Open Access Journals (Sweden)

    Zohoori Salar

    2017-09-01

    Full Text Available Fabrication of electro-conductive fiber is a novel process. Nanocomposites of multiwall carbon nanotube/polyamide66 were produced by electrospinning with different amounts of multiwall carbon nanotube. Field emission scanning electron microscope and Fourier transform infrared spectroscopy of samples proved the existence of multiwall carbon nanotube distribution in polyamide 66 nanofibers. Results showed that electro conductivity of electrospun multiwall carbon nanotube/polyamide 66 nano fiber has increased in comparison with electrospun polyamide 66. Moreover, UV blocking of samples was investigated which has shown that using multiwall carbon nanotube in polyamide 66 increases UV blocking of fibers. Furthermore, anti-bacterial activity of nanocomposite showed that these nanocomposites have antibacterial property against both Staphylococcus Aureus and Escherichia Coli bacteria according to AATCC test method.

  16. Effect of repair resin type and surface treatment on the repair strength of polyamide denture base resin.

    Science.gov (United States)

    Gundogdu, Mustafa; Yanikoglu, Nuran; Bayindir, Funda; Ciftci, Hilal

    2015-01-01

    The purpose of the present study was to evaluate the effects of different repair resins and surface treatments on the repair strength of a polyamide denture base material. Polyamide resin specimens were prepared and divided into nine groups according to the surface treatments and repair materials. The flexural strengths were measured with a 3-point bending test. Data were analyzed with a 2-way analysis of variance, and the post-hoc Tukey test (α=0.05). The effects of the surface treatments on the surface of the polyamide resin were examined using scanning electron microscopy. The repair resins and surface treatments significantly affected the repair strength of the polyamide denture base material (p0.05). The flexural strength of the specimens repaired with the polyamide resin was significantly higher than that of those repaired with the heat-polymerized and autopolymerizing acrylic resins.

  17. MRI diagnosis of the complications of polyamide hydrogel injection for augmentation mammoplasty

    International Nuclear Information System (INIS)

    Chen Xueqiang; Chen Pingyou; Zhang Yunshu; Luo Qinghua; Xu Rong

    2005-01-01

    Objective: To analyze MRI findings and its clinical significance in complications of polyamide hydrogel injection for augmentation mammoplasty. Methods: The complication findings of MR imaging in 20 cases with polyamide hydrogel injection for augmentation mammoplasty were retrospectively reviewed and analyzed. Results: In 20 patients, 26 breasts suffered from complications, including infection (n=5) with pieces of long T 1 and long T 2 signals, aseptic inflammation (n=2) with pieces of slight long T 1 and moderate T 2 signals, hard nodule (n=10) with long T 1 and long T 2 signals, and rupture (n=5) with pieces and nodes of long T 1 and long T 2 signals on MR images. Conclusion: MRI has the great diagnostic value in the detection of complications after polyamide hydrogel injection for augmentation mammoplasty, and it should be taken as the first diagnostic choice. (authors)

  18. Retention and Deformation of Cobalt-Chromium and High-Impact Polyamide Clasps

    Directory of Open Access Journals (Sweden)

    Övül Kümbüloğlu

    2018-04-01

    Full Text Available Objective: The use of metal clasps especially in anterior region may cause aesthetic problems. Polyamide resin has been suggested as an alternative aesthetic denture clasp material. This study compared the retentive force and deformation of cobalt-chromium and polyamide clasps after 36 months of simulated clinical use. Materials and Methods: The retentive force for clasp removal was measured in distilled water using a custom-made apparatus with intervals corresponding to 0, 6, 12, 18, 24, 30 and 36 months of simulated clinical use. The distance (mm between the retentive and reciprocal clasp tips was measured using a microscope before and after the insertion-removal procedures. Results: Significant difference was observed in distance between clasp tips for metal clasps between baseline and 36 months for molars and premolars (p0.05. Conclusion: Polyamide clasps could be alternative to metal clasps particularly on premolars with reliable retention and deformation.

  19. Orientation and the extent of exfoliation of clay on scratch damage in polyamide 6 nanocomposites

    International Nuclear Information System (INIS)

    Dasari, Aravind; Yu Zhongzhen; Mai Yiuwing; Kim, Jang-Kyo

    2008-01-01

    The major objectives of this work are to understand the effects of organoclay, its extent of exfoliation and orientation, and indenter geometry on the scratch characteristics of polyamide 6/organoclay nanocomposites. Two different organically treated clays are used for this purpose and their structural parameters in a polyamide 6 matrix quantified. It is shown that, while the material properties are important for scratching resistance, they are not the only determinants of the scratch performance of materials. Further, despite proving beneficial to scratch resistance, in terms of residual depth, the presence (and exfoliation) of organoclay promotes the formation of brittle cracks during scratching. But with no organoclay layers, plastic flow controls the scratch damage in neat polyamide 6 with large residual depths. Factors such as orientation of clay layers and variations of indenter tip geometry also exert dominant effects on scratch penetration resistance and damage. Additionally, significant plastic flow and rotation of organoclay layers from the original configuration are observed underneath the sliding indenter

  20. Aromatic-aliphatic polyamide/montmorillonite clay nanocomposite materials: Synthesis, nanostructure and properties

    International Nuclear Information System (INIS)

    Zulfiqar, Sonia; Ahmad, Zahoor; Ishaq, Muhammad; Sarwar, Muhammad Ilyas

    2009-01-01

    New type of aromatic-aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T g ) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability.

  1. Aromatic-aliphatic polyamide/montmorillonite clay nanocomposite materials: Synthesis, nanostructure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Zulfiqar, Sonia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ahmad, Zahoor [Department of Chemistry, Faculty of Science, Kuwait University, P. O. Box: 5969, Safat 13060 (Kuwait); Ishaq, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Sarwar, Muhammad Ilyas, E-mail: ilyassarwar@hotmail.com [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States)

    2009-11-15

    New type of aromatic-aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T{sub g}) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability.

  2. Mechanical and rheological properties of nanocomposites of polyamide 6 with national organoclay

    International Nuclear Information System (INIS)

    Paz, Rene Anisio da; Leite, Amanda Melissa Damiao; Araujo, Edcleide Maria; Melo, Tomas Jeferson Alves de; Pessan, Luiz Antonio; Passador, Fabio Roberto

    2013-01-01

    Nanocomposites of polyamide 6 with organoclay were prepared by melt intercalation and their rheological and mechanical properties were studied. The clay was treated with the quaternary ammonium salt (Cetremide) and characterized by Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed the incorporation of salt in the clay and its organophilization. A master was prepared with PA6/clay (1:1) by weight and this was added to the pure polyamide 6 to reach the nominal proportion of 3% of clay, using a co-rotational twin screw extruder. The samples were molded by injection and characterized by: capillary rheometry, XRD, TEM and mechanical testing (tensile and impact). The results of capillary rheometry showed that the presence of organoclay in the PA6 increased the viscosity of the systems. With XRD and TEM, it was verified that all systems presented predominantly exfoliated structure. The tensile properties of the nanocomposites were better than those of pure polyamide 6. (author)

  3. Morphologic characterization for XRD and TEM of polyamide 6 and 66 nanocomposites with bentonite regional clay

    International Nuclear Information System (INIS)

    Leite, Amanda M.D.; Medeiros, Vanessa da N.; Maia, Larissa F.; Araujo, Edcleide M.; Lira, Helio L.

    2009-01-01

    Polyamide 6 and 66 nanocomposites with clay consisting of silicates layer from Paraiba were produced. The clay was modified being used the quaternary salt of ammonium Cetremide, this so there is a better interaction of the clay with polymeric matrix. The clay without treatment (MMT) and treated clay was evaluated by XRD that showed the insertion of the salt molecules into silicates layer. The nanocomposites were obtained from polyamide 6 and 66 were verified that these presented morphological structure composed of exfoliated/partially exfoliated, analyzed by XRD and TEM. (author)

  4. Mechanisms of formation and destruction of nitrogen oxides during polyamide incineration in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Hahnel, F; Gadiou, R; Prado, G [Univ. de Haute Alsace, Mulhouse (France). Lab. de Gestion des Risques et Environnement

    1998-09-01

    In order to study the incineration of nitrogen-containing polymers, a fludized bed has been built. This paper reports the results for polyamide 6-6 incineration. The main nitrogen containing species have been identified, and the axial profiles of concentration of nitrogen oxides, HCN and NH3 have been measured. The main steps of decomposition of the polyamide were identified. We present an experimental investigation of the influence of operating parameters (temperature, excess air) on the formation and reduction of polymer combustion products. The yields of conversion of nitrogen to the different N-species have been calculated as a function of excess air in the fluidized bed. (orig.)

  5. Rheological changes of polyamide 12 under oscillatory shear

    Science.gov (United States)

    Mielicki, C.; Gronhoff, B.; Wortberg, J.

    2014-05-01

    Changes in material properties as well as process deviation prevent Laser Sintering (LS) technology from manufacturing of quality assured parts in a series production. In this context, the viscosity of Polyamide 12 (PA12) is assumed to possess the most significant influence, as it determines the sintering velocity, the resistance towards melt formation and the bonding strength of sintered layers. Moreover, the viscosity is directly related to the structure of the molten polymer. In particular, it has been recently reported that LS process conditions lead to structural changes of PA12 affecting viscosity and coalescence of adjacent polymer particles, i.e. melt formation significantly. Structural change of PA12 was understood as a post condensation. Its influence on viscosity was described by a time and temperature depending rheological model whereas time dependence was considered by a novel structural change shift factor which was derived from melt volume rate data. In combination with process data that was recorded using online thermal imaging, the model is suitable to control the viscosity (processability of the material) as result of material and process properties. However, as soon as laser energy is exposed to the powder bed PA12 undergoes a phase transition from solid to molten state. Above the melting point, structural change is expected to occur faster due to a higher kinetic energy and free volume of the molten polymer. Oscillatory shear results were used to study the influence of aging time and for validation of the novel structural change shift factor and its model parameters which were calibrated based on LS processing condition.

  6. Mechanical properties of hybrid SiC/CNT filled toughened epoxy nanocomposite

    Science.gov (United States)

    Ratim, S.; Ahmad, S.; Bonnia, N. N.; Yahaya, Sabrina M.

    2018-01-01

    Mechanical properties of epoxy nanocomposites filled single filler have been extensively studied by various researchers. However, there are not much discovery on the behavior of hybrid nanocomposite. In this study, single and hybrid nanocomposites of toughened epoxy filled CNT/SiC nanoparticles were investigated. The hybrid nanocomposites samples were prepared by combining CNT and SiC nanoparticles in toughened epoxy matrix via mechanical stirring method assisted with ultrasonic cavitations. Epoxy resin and liquid epoxidized natural rubber (LENR) mixture were first blend prior to the addition of nanofillers. Then, the curing process of the nanocomposite samples were conducted by compression molding technique at 130°C for 2 hours. The purpose of this study is to investigate the hybridization effect of CNT and SiC nanoparticles on mechanical properties toughened epoxy matrix. The total loading of single and hybrid nanofillers were fixed to 4% volume are 0, 4C, 4S, 3S1C, 2S2C, and 1S3C. Mechanical properties of hybrid composites show that the highest value of tensile strength achieved by 3S1C sample at about 7% increment and falls between their single composite values. Meanwhile, the stiffness of the same sample is significantly increased at about 31% of the matrix. On the other hand, a highest flexural property is obtained by 1S3C sample at about 20% increment dominated by CNT content. However, the impact strength shows reduction trend with the addition of SiC and CNT into the matrix. The hybridization of SiC and CNT show highest value in sample 1S3C at about 3.37 kJ/m2 of impact energy absorbed. FESEM micrograph have confirmed that better distributions and interaction observed between SiC nanoparticles and matrix compared to CNT, which contributed to higher tensile strength and modulus.

  7. Thermomechanical response and toughening mechanisms of a carbon nano bead reinforced epoxy composite

    Energy Technology Data Exchange (ETDEWEB)

    Goyat, M.S., E-mail: goyatmanjeetsingh@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India); Suresh, Sumit; Bahl, Sumit [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India); Halder, Sudipta [Department of Mechanical Engineering, National Institute of Technology, Silchar, 788010, Assam (India); Ghosh, P.K. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India)

    2015-09-15

    The current research on carbon nano beads (CNB) is focused on various applications such as high strength nanocomposites, electronic devices, lubricants, semiconductors, and high-performance batteries, etc. The commercial uses of CNB are yet juvenile for the market. Only limited results have been published so far on CNB reinforced polymers [1]. This study highlights the synthesis of uniform size, spherical CNB using chemical vapour deposition (CVD) method. The synthesized CNB are introduced into epoxy matrix by ultrasonic dual mode mixing route to produce CNB/epoxy nanocomposite. The CNB are characterized by X-ray diffraction, Energy dispersive X-ray analysis and field emission scanning electron microscope (FESEM). Morphology, thermal and mechanical properties of the CNB/epoxy nanocomposites is characterized by FESEM, Thermo-gravimetric analyzer and tensile and bending tests respectively. A noticeable improvement in thermal and mechanical properties of CNB reinforced epoxy matrix with low nanofiller content is observed. Several toughening mechanisms such as particle pull out, crack deflection, particle bridging, crack pinning, shear yielding or plastic deformation, and microcracking are identified. But, only the crack deflection, particle bridging and shear yielding or plastic deformations are recognized as the leading toughening mechanisms for CNB/epoxy nanocomposite. These results can be considered as symptomatic of a potential CNB espousal in new composites. - Highlights: • Synthesis of uniform size, spherical CNB using chemical vapour deposition method. • Fabrication of CNB/epoxy nanocomposites by ultrasonic dual mode mixing route. • Significant enhancement in thermomechanical properties of CNB/epoxy nanocomposite. • Main toughening mechanisms: Crack deflection, particle bridging and shear yielding.

  8. Thermomechanical response and toughening mechanisms of a carbon nano bead reinforced epoxy composite

    International Nuclear Information System (INIS)

    Goyat, M.S.; Suresh, Sumit; Bahl, Sumit; Halder, Sudipta; Ghosh, P.K.

    2015-01-01

    The current research on carbon nano beads (CNB) is focused on various applications such as high strength nanocomposites, electronic devices, lubricants, semiconductors, and high-performance batteries, etc. The commercial uses of CNB are yet juvenile for the market. Only limited results have been published so far on CNB reinforced polymers [1]. This study highlights the synthesis of uniform size, spherical CNB using chemical vapour deposition (CVD) method. The synthesized CNB are introduced into epoxy matrix by ultrasonic dual mode mixing route to produce CNB/epoxy nanocomposite. The CNB are characterized by X-ray diffraction, Energy dispersive X-ray analysis and field emission scanning electron microscope (FESEM). Morphology, thermal and mechanical properties of the CNB/epoxy nanocomposites is characterized by FESEM, Thermo-gravimetric analyzer and tensile and bending tests respectively. A noticeable improvement in thermal and mechanical properties of CNB reinforced epoxy matrix with low nanofiller content is observed. Several toughening mechanisms such as particle pull out, crack deflection, particle bridging, crack pinning, shear yielding or plastic deformation, and microcracking are identified. But, only the crack deflection, particle bridging and shear yielding or plastic deformations are recognized as the leading toughening mechanisms for CNB/epoxy nanocomposite. These results can be considered as symptomatic of a potential CNB espousal in new composites. - Highlights: • Synthesis of uniform size, spherical CNB using chemical vapour deposition method. • Fabrication of CNB/epoxy nanocomposites by ultrasonic dual mode mixing route. • Significant enhancement in thermomechanical properties of CNB/epoxy nanocomposite. • Main toughening mechanisms: Crack deflection, particle bridging and shear yielding.

  9. Elastomer toughened polyimide adhesives. [bonding metal and composite material structures for aircraft and spacecraft

    Science.gov (United States)

    St.clair, A. K.; St.clair, T. L. (Inventor)

    1985-01-01

    A rubber-toughened, addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber-containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride has been mixed, and utilizing solvent or mixture of solvents for the reaction.

  10. Sub-10-micrometer toughening and crack tip toughness of dental enamel

    OpenAIRE

    Ang, Siang Fung; Schulz, Anja; Pacher Fernandes, Rodrigo; Schneider, Gerold A.

    2011-01-01

    In previous studies, enamel showed indications to occlude small cracks in-vivo and exhibited R-curve behaviors for bigger cracks ex-vivo. This study quantifies the crack tip toughness (KI0, KIII0), the crack closure stress and the cohesive zone size at the crack tip of enamel and investigates the toughening mechanisms near the crack tip down to the length scale of a single enamel crystallite. The crack-opening-displacement (COD) profile of cracks induced by Vickers indents on mature bovine en...

  11. An investigation on the crack growth resistance of human tooth enamel: Anisotropy, microstructure and toughening

    Science.gov (United States)

    Yahyazadehfar, Mobin

    The enamel of human teeth is generally regarded as a brittle material with low fracture toughness. Consequently, the contributions of this tissue in resisting tooth fracture and the importance of its complex microstructure have been largely overlooked. The primary objective of this dissertation is to characterize the role of enamel's microstructure and degree of decussation on the fracture behavior of human enamel. The importance of the protein content and aging on the fracture toughness of enamel were also explored. Incremental crack growth in sections of human enamel was achieved using a special inset Compact Tension (CT) specimen configuration. Crack extension was achieved in two orthogonal directions, i.e. longitudinal and transverse to the prism axes. Fracture surfaces and the path of crack growth path were evaluated using scanning electron microscopy (SEM) to understand the fundamental mechanisms of crack growth extension. Furthermore, a hybrid approach was adopted to quantify the contribution of toughening mechanisms to the overall toughness. Results of this investigations showed that human enamel exhibits rising R-curve for both directions of crack extension. Cracks extending transverse to the rods in the outer enamel achieved lower rise in toughness with crack extension, and significantly lower toughness (1.23 +/- 0.20 MPa·m 0.5) than in the inner enamel (1.96 +/- 0.28 MPa· 0.5) and in the longitudinal direction (2.01 +/- 0.21 MPa· 0.5). The crack growth resistance exhibited both anisotropy and inhomogeneity, which arise from the complex hierarchical microstructure and the decussated prism structure. Decussation causes deflection of cracks extending from the enamel surface inwards, and facilitates a continuation of transverse crack extension within the outer enamel. This process dissipates fracture energy and averts cracks from extending toward the dentin and vital pulp. This study is the first to investigate the importance of proteins and the effect of

  12. Systems design of transformation toughened blast-resistant naval hull steels

    Science.gov (United States)

    Saha, Arup

    A systems approach to computational materials design has demonstrated a new class of ultratough, weldable secondary hardened plate steels combining new levels of strength and toughness while meeting processability requirements. A first prototype alloy has achieved property goals motivated by projected naval hull applications requiring extreme fracture toughness (Cv > 85 ft-lbs (115 J) corresponding to KId > 200 ksi.in1/2 (220 MPa.m1/2)) at strength levels of 150--180 ksi (1034--1241 MPa) yield strength in weldable, formable plate steels. A theoretical design concept was explored integrating the mechanism of precipitated nickel-stabilized dispersed austenite for transformation toughening in an alloy strengthened by combined precipitation of M2C carbides and BCC copper both at an optimal ˜3nm particle size for efficient strengthening. This concept was adapted to plate steel design by employing a mixed bainitic/martensitic matrix microstructure produced by air-cooling after solution-treatment and constraining the composition to low carbon content for weldability. With optimized levels of copper and M2C carbide formers based on a quantitative strength model, a required alloy nickel content of 6.5 wt% was predicted for optimal austenite stability for transformation toughening at the desired strength level of 160 ksi (1100 MPa) yield strength. A relatively high Cu level of 3.65 wt% was employed to allow a carbon limit of 0.05 wt% for good weldability. Hardness and tensile tests conducted on the designed prototype confirmed predicted precipitation strengthening behavior in quench and tempered material. Multi-step tempering conditions were employed to achieve the optimal austenite stability resulting in significant increase of impact toughness to 130 ft-lb (176 J) at a strength level of 160 ksi (1100 MPa). Comparison with the baseline toughness-strength combination determined by isochronal tempering studies indicates a transformation toughening increment of 60% in Charpy

  13. A reactive polystyrene-block-polyisoprene star copolymer as a toughening agent in an epoxy thermoset

    KAUST Repository

    Francis, Raju

    2015-12-29

    © 2015 Springer-Verlag Berlin Heidelberg A polystyrene-block-polyisoprene ((PS-b-PI)3) star polymer was synthesized by photochemical reversible addition fragmentation chain transfer (RAFT) polymerization. The obtained star polymer was epoxidized and used as a toughening agent in an epoxy thermoset. The incorporation of the epoxidized star polymer resulted in the formation of nanostructures and it was fixed by a crosslinking reaction. The formation of nanostructures in the thermosets follows the mechanism of reaction-induced microphase separation. The mechanical properties such as toughness and tensile strength were considerably increased due to the nanostructures formed by reactive blending.

  14. Effects of reuse and bleach/formaldehyde reprocessing on polysulfone and polyamide hemodialyzers.

    Science.gov (United States)

    Cornelius, Rena M; McClung, W Glenn; Barre, Paul; Esguerra, Fe; Brash, John L

    2002-01-01

    The surface features, morphology, and blood interactions of fibers from pristine, bleach/formaldehyde reprocessed, and reused Fresenius Polysulfone High Flux (Hemoflow F80B) hemodialyzers and Gambro Polyflux 21S Polyamide hemodialyzers have been studied. SEM images of fibers from both hemodialyzer types revealed a dense skin layer on the inner surface and a relatively thick porous layer on the outer surface. The 21S polyamide support layer consisted of interconnected highly porous structures. Environmental scanning electron microscopy and atomic force microscopy images of both membrane types showed alterations in morphology due to reprocessing and reuse; however the changes were more marked for the 21S polyamide dialyzers. Fluorescence microscopy images showed only minimal fluorescence associated with the fibers after patient use and reprocessing, suggesting that blood derived deposits were removed by processing. The protein layers formed on pristine and reused hemodialyzer membranes during clinical use were studied using SDS-PAGE and immunoblotting. Before bleach/formaldehyde treatment, protein layers of considerable amount and complexity were found on the blood side of singly and multiply used dialyzers. Proteins adsorbed on the dialysate side were predominantly in the molecular mass region below 30 kDa. However, some higher molecular mass proteins were detected on the dialysate side of the 21 S polyamide dialyzers. Very little protein was detected on dialyzers that were treated with bleach/formaldehyde after dialysis, regardless of whether they had been used/reprocessed once or 12 times.

  15. Radiolytic crosslinking and chain scission in aliphatic and alkyl-aromatic polyamides: Pt. 2

    International Nuclear Information System (INIS)

    Lyons, B.J.; Glover, L.C. Jr.

    1991-01-01

    Regression analysis of the radiation parameters of nine aliphatic polyamides exposed to ionizing radiation leads to the conclusion that the decline in the ratio of chain scission to crosslinking in higher aliphatic polyamides is best related to the linear increase in the methylene content of, or the number of methylene groups in, the polyamide repeat unit. G(crosslink)[G(X)] and G(chain scission) [G(CS)] values, however, do not correlate well with either of these parameters. Rather it is found that the major determinant of yields [about 80-85% of the variation for G(X), 70% for G(CS)] is the number of hydrogen atoms or methylene groups in the amine residue. Although, logically, the yields of crosslinks and chain scissions in polyamides would be expected to tend to that of polyethylene as the number of methylene groups in the repeat unit increases, use of two models assuming an exponential trend to the G(X) value characteristic of polyethylene in the analysis did not provide better fits to the data than the simple linear model referred to above. Indeed, the assumption of a significant exponential trend factor led to a marked drop in the goodness of fit. (author)

  16. Comparison of Three Different Methods for Pile Integrity Testing on a Cylindrical Homogeneous Polyamide Specimen

    Science.gov (United States)

    Lugovtsova, Y. D.; Soldatov, A. I.

    2016-01-01

    Three different methods for pile integrity testing are proposed to compare on a cylindrical homogeneous polyamide specimen. The methods are low strain pile integrity testing, multichannel pile integrity testing and testing with a shaker system. Since the low strain pile integrity testing is well-established and standardized method, the results from it are used as a reference for other two methods.

  17. Influence of moisture absorption on properties of fiber reinforced polyamide 6 composites

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Løgstrup Andersen, Tom; Lystrup, Aage

    2011-01-01

    sensitive to moisture, and if PA6 is used as matrix material in a fiber composite, the properties of the fiber composite will depend on the moisture content of the material. At standard condition (23 °C and 50% RH) polyamide6 absorbs about 3 weight-% of water, whereas the PA6 material is dry right after...

  18. Living Polycondensation: Synthesis of Well-Defined Aromatic Polyamide-Based Polymeric Materials

    KAUST Repository

    Alyami, Mram Z.

    2016-11-01

    Chain growth condensation polymerization is a powerful tool towards the synthesis of well-defined polyamides. This thesis focuses on one hand, on the synthesis of well-defined aromatic polyamides with different aminoalkyl pendant groups with low polydispersity and controlled molecular weights, and on the other hand, on studying their thermal properties. In the first project, well-defined poly (N-octyl-p-aminobenzoate) and poly (N-butyl-p-aminobenzoate) were synthesized, and for the first time, their thermal properties were studied. In the second project, ethyl4-aminobenzoate, ethyl 4-octyl aminobenzoate and 4-(hydroxymethyl) benzoic acid were used as novel efficient initiators of ε-caprolactone with t-BuP2 as a catalyst. Macroinitiator and Macromonomer of poly (ε-caprolactone) were synthesized with ethyl 4-octyl aminobenzoate and ethyl 4-aminobenzoate as initiators to afford polyamide-block-poly (ε-caprolactone) and polyamide-graft-poly (ε-caprolactone) by chain growth condensation polymerization (CGCP). In the third project, a new study has been done on chain growth condensation polymerization to discover the probability to synthesize new polymers and studied their thermal properties. For this purpose, poly (N-cyclohexyl-p-aminobenzoate) and poly (N-hexyl-p-aminobenzoate) were synthesized with low polydispersity and controlled molecular weights.

  19. Applications of polyamide/cellulose fiber/wollastonite composites for microcellular injection molding

    Science.gov (United States)

    Herman Winata; Lih-Sheng Turng; Daniel F. Caulfield; Tom Kuster; Rick Spindler; Rod Jacobson

    2003-01-01

    In this study, a cellulose-fiber-reinforced Polyamide-6 (PA-6) composite, a hybrid composite (PA-6/cellulose/Wollastonite), and the neat PA-6 resin were injection molded into ASTM test–bar samples with conventional and microcellular injection molding. The impact and tensile strengths of molded samples were measured and the Scanning Electron Microscopy (SEM) images were...

  20. Mechanical Characterization and Fractography of Glass Fiber/Polyamide (PA6) Composites

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Pillai, Saju; Charca, Samuel

    2015-01-01

    The mechanical properties of the glass fiber reinforced Polyamide (PA6) composites made by prepreg tapes and commingled yarns were studied by in-plane compression, short-beam shear, and flexural tests. The composites were fabricated with different fiber volume contents (prepregs—47%, 55%, 60%, an...

  1. Aluminum hypophosphite microencapsulated to improve its safety and application to flame retardant polyamide 6

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Hua [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Tang, Gang [School of Architecture and Civil Engineering, Anhui University of Technology, 59 Hudong Road, Ma’anshan, Anhui 243002 (China); Hu, Wei-Zhao; Wang, Bi-Bo; Pan, Ying [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Song, Lei, E-mail: leisong@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road, Suzhou, Jiangsu 215123 (China)

    2015-08-30

    Highlights: • MCAHP was prepared and applied in polyamide 6. • MCA as the capsule material can improve the fire safety of AHP. • Flame retardant polyamide 6 composites with MCAHP show good flame retardancy. - Abstract: Aluminum hypophosphite (AHP) is an effective phosphorus-containing flame retardant. But AHP also has fire risk that it will decompose and release phosphine which is spontaneously flammable in air and even can form explosive mixtures with air in extreme cases. In this paper, AHP has been microencapsulated by melamine cyanurate (MCA) to prepare microencapsulated aluminum hypophosphite (MCAHP) with the aim of enhancing the fire safety in the procedure of production, storage and use. Meanwhile, MCA was a nitrogen-containing flame retardant that can work with AHP via the nitrogen-phosphorus synergistic effect to show improved flame-retardant property than other capsule materials. After microencapsulation, MCA presented as a protection layer inhibit the degradation of AHP and postpone the generation of phosphine. Furthermore, the phosphine concentration could be effectively diluted by inert decomposition products of MCA. These nonflammable decomposition products of MCA could separate phosphine from air delay the oxidizing reaction with oxygen and decrease the heat release rate, which imply that the fire safety of AHP has been improved. Furthermore, MCAHP was added into polyamide 6 to prepare flame retardant polyamide 6 composites (FR-PA6) which show good flame retardancy.

  2. Aluminum hypophosphite microencapsulated to improve its safety and application to flame retardant polyamide 6

    International Nuclear Information System (INIS)

    Ge, Hua; Tang, Gang; Hu, Wei-Zhao; Wang, Bi-Bo; Pan, Ying; Song, Lei; Hu, Yuan

    2015-01-01

    Highlights: • MCAHP was prepared and applied in polyamide 6. • MCA as the capsule material can improve the fire safety of AHP. • Flame retardant polyamide 6 composites with MCAHP show good flame retardancy. - Abstract: Aluminum hypophosphite (AHP) is an effective phosphorus-containing flame retardant. But AHP also has fire risk that it will decompose and release phosphine which is spontaneously flammable in air and even can form explosive mixtures with air in extreme cases. In this paper, AHP has been microencapsulated by melamine cyanurate (MCA) to prepare microencapsulated aluminum hypophosphite (MCAHP) with the aim of enhancing the fire safety in the procedure of production, storage and use. Meanwhile, MCA was a nitrogen-containing flame retardant that can work with AHP via the nitrogen-phosphorus synergistic effect to show improved flame-retardant property than other capsule materials. After microencapsulation, MCA presented as a protection layer inhibit the degradation of AHP and postpone the generation of phosphine. Furthermore, the phosphine concentration could be effectively diluted by inert decomposition products of MCA. These nonflammable decomposition products of MCA could separate phosphine from air delay the oxidizing reaction with oxygen and decrease the heat release rate, which imply that the fire safety of AHP has been improved. Furthermore, MCAHP was added into polyamide 6 to prepare flame retardant polyamide 6 composites (FR-PA6) which show good flame retardancy

  3. Comparison of the properties polyamide 6.6 surfaces treated by plasma and by ionizing radiation

    International Nuclear Information System (INIS)

    Irineu, Rosa Maria da Silva

    2010-01-01

    This study aims to compare the surface properties of polyamide 6.6 plasma treatment and ionizing radiation, as well as determine the best technique and condition of the surface activation, adhesion of the same order and polyacrylic rubber used in manufacturing of automotive retainers. Treatment of polyamide 6.6 plasma was performed using an equipment 'Electronic Diener - Plasma - Surface-Technology LFG40' with nitrogen gas at a pressure of 1.40 kg/cm 2 . Samples of polyamide 6.6 were also treated with ionizing radiation, atmospheric pressure and in vacuum, using an industrial electron accelerator, Dynamitron JOB 188 with radiation dose of 5, 10, 20, 40, 50, 100, 200, 300, 400 and 500kGy with a dose rate of 11.22 kGy/s for all doses and rate of 11.22 kGy/s and 22.38 kGy/s for a dose of 20kGy. After the processes of surface modification of polyamide 6.6, part of the untreated samples, treated by plasma and by ionizing radiation were incorporated into the polyacrylic rubber, and another part was designed to characterize the surface using the techniques of SEM / EDS, FT- IR, PIXE / RBS, AFM and contact angle. Untreated samples and the irradiated samples did not join the polyacrylic rubber. The samples treated by plasma joined the polyacrylic rubber efficiently and showed differences in roughness in SEM and AFM, and an increase in contact angle when compared with untreated samples. The irradiated samples showed no significant differences in the analysis of properties used in this study when compared with untreated samples. Ionizing radiation was not effective in surface modification of polyamide 6.6 for adherence with polyacrylic rubber. (author)

  4. Study on Strengthening and Toughening Mechanisms of Aluminum Alloy 2618-Ti at Elevated Temperature

    Science.gov (United States)

    Kun, Ma; Tingting, Liu; Ya, Liu; Xuping, Su; Jianhua, Wang

    2018-01-01

    The tensile properties of the alloy 2618 and 2618-Ti were tested using a tensile testing machine. The morphologies of the fracture of tensile samples were observed using scanning electron microscopy. The strengthening and toughening mechanisms of alloy 2618-Ti at elevated temperature were systematically investigated based on the analyses of experimental results. The results showed that the tensile strength of alloy 2618-Ti is much higher than that of alloy 2618 at the temperature range of 250 and 300 °C. But the elongation of alloy 2618-Ti is much higher than that of alloy 2618 at the temperature range of 200 and 300 °C. The equal-strength temperature of intragranular and grain boundary of alloy 2618-Ti is about 235 °C. When the temperature is lower than 235 °C, the strengthening of alloy 2618-Ti is ascribed to the strengthening effect of fine grains and dispersed Al3Ti/Al18Mg3Ti2 phase. When the temperature is higher than 235 °C, the strengthening effect of alloy 2618-Ti is mainly attributed to the load transfer of Al3Ti and Al18Mg3Ti2 particles. The toughening of alloy 2618-Ti at elevated temperature is mainly ascribed to the fine grain microstructure, excellent combination between matrix and dispersed Al3Ti/Al18Mg3Ti2 particles as well as the recrystallization of the alloy at elevated temperature.

  5. Toughening MoSi2 with Niobium metal -- Effects of size and orientation of ductile laminae

    International Nuclear Information System (INIS)

    Shaw, L.; Abbaschian, R.

    1994-01-01

    Effects of size and orientation of ductile laminae on the toughness of brittle matrix composites have been evaluated using MoSi 2 composites reinforced with Nb laminae. Nb laminae with thicknesses ranging from 0.127 to 1.0 mm were hot pressed with MoSi 2 powder to prepare the composites. Toughness of the composites was measured using four-point bend test on chevron-notched specimens. It was found that the toughness of the composites increased with increasing size of the niobium laminae. Furthermore, toughening was observed at crack propagation directions perpendicular to the laminae plane, indicating that ductile laminae offer two dimensional toughening. A model based on the bridging contribution of the ductile phase has been proposed to analyze the chevron-notched specimens of the ductile-phase-reinforced brittle matrix composites. The analysis showed that the dependence of the toughness of the composites on the size and orientation of the ductile laminae could be interpreted in terms of their bridging capability and bending contributions

  6. Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates.

    Science.gov (United States)

    Knowles, Alexander J; Bhowmik, Ayan; Purkayastha, Surajit; Jones, Nicholas G; Giuliani, Finn; Clegg, William J; Dye, David; Stone, Howard J

    2017-10-01

    The data presented in this article are related to the research article entitled "Laves phase intermetallic matrix composite in situ toughened by ductile precipitates" (Knowles et al.) [1]. The composite comprised a Fe 2 (Mo, Ti) matrix with bcc (Mo, Ti) precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al.) [1]. Here, details are given on a focused ion beam (FIB) slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti) precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM)) micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX) maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP) and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al.) [1] along with details of the transformation matrix determined.

  7. Bridge toughening enhancement in double-notched MoSi2/Nb model composites

    International Nuclear Information System (INIS)

    Pickard, S.M.; Ghosh, A.K.

    1996-01-01

    Single-ply composites containing both laminate and continuous Nb fiber reinforcement coated with Al 2 O 3 debond coatings in an MoSi 2 matrix are used as model systems for investigating bridge toughening concepts for various precrack configurations., When cracks are introduced symmetrically on either side of the ductile phase with zero crack offset spacing (S = 0), a minimum amount of energy is expended in plastic deformation and the local rupture process in the metal, as measured by the area of the force displacement curve in tension. For asymmetric precracks introduced on either side of the ductile reinforcement, as the offset spacing, S, was varied from 1 to 20 R (R being the ductile phase half-thickness), the overall extension continuously increased within the bridging ligament. The effective ligament gage length was nearly equal to the crack spacing in the limiting case of a weak interface. However, the ductile Nb phase developed a Nb 5 Si 3 reaction layer on its surface which was strongly bonded to the Nb and was found to undergo periodic cracking, leading to numerous shear bands within the ductile phase. This unique and previously unreported mode of metal deformation in shear loading has been analyzed using a simple geometric model. The results indicate that the profusion of shear bands is the primary source of toughening enhancement in the case of asymmetric crack geometry, which was not recognized in prior work of this type

  8. Zirconia toughened SiC whisker reinforced alumina composites small business innovation research

    Science.gov (United States)

    Loutfy, R. O.; Stuffle, K. L.; Withers, J. C.; Lee, C. T.

    1987-01-01

    The objective of this phase 1 project was to develop a ceramic composite with superior fracture toughness and high strength, based on combining two toughness inducing materials: zirconia for transformation toughening and SiC whiskers for reinforcement, in a controlled microstructure alumina matrix. The controlled matrix microstructure is obtained by controlling the nucleation frequency of the alumina gel with seeds (submicron alpha-alumina). The results demonstrate the technical feasibility of producing superior binary composites (Al2O3-ZrO2) and tertiary composites (Al2O3-ZrO2-SiC). Thirty-two composites were prepared, consolidated, and fracture toughness tested. Statistical analysis of the results showed that: (1) the SiC type is the key statistically significant factor for increased toughness; (2) sol-gel processing with a-alumina seed had a statistically significant effect on increasing toughness of the binary and tertiary composites compared to the corresponding mixed powder processing; and (3) ZrO2 content within the range investigated had a minor effect. Binary composites with an average critical fracture toughness of 6.6MPam sup 1/2, were obtained. Tertiary composites with critical fracture toughness in the range of 9.3 to 10.1 MPam sup 1/2 were obtained. Results indicate that these composites are superior to zirconia toughened alumina and SiC whisker reinforced alumina ceramic composites produced by conventional techniques with similar composition from published data.

  9. Giant panda׳s tooth enamel: Structure, mechanical behavior and toughening mechanisms under indentation.

    Science.gov (United States)

    Weng, Z Y; Liu, Z Q; Ritchie, R O; Jiao, D; Li, D S; Wu, H L; Deng, L H; Zhang, Z F

    2016-12-01

    The giant panda׳s teeth possess remarkable load-bearing capacity and damage resistance for masticating bamboos. In this study, the hierarchical structure and mechanical behavior of the giant panda׳s tooth enamel were investigated under indentation. The effects of loading orientation and location on mechanical properties of the enamel were clarified and the evolution of damage in the enamel under increasing load evaluated. The nature of the damage, both at and beneath the indentation surfaces, and the underlying toughening mechanisms were explored. Indentation cracks invariably were seen to propagate along the internal interfaces, specifically the sheaths between enamel rods, and multiple extrinsic toughening mechanisms, e.g., crack deflection/twisting and uncracked-ligament bridging, were active to shield the tips of cracks from the applied stress. The giant panda׳s tooth enamel is analogous to human enamel in its mechanical properties, yet it has superior hardness and Young׳s modulus but inferior toughness as compared to the bamboo that pandas primarily feed on, highlighting the critical roles of the integration of underlying tissues in the entire tooth and the highly hydrated state of bamboo foods. Our objective is that this study can aid the understanding of the structure-mechanical property relations in the tooth enamel of mammals and further provide some insight on the food habits of the giant pandas. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Study of the toughening mechanisms in bone and biomimetic hydroxyapatite materials using Raman microprobe spectroscopy.

    Science.gov (United States)

    Pezzotti, Giuseppe; Sakakura, Seiji

    2003-05-01

    A Raman microprobe spectroscopy characterization of microscopic fracture mechanisms is presented for a natural hydroxyapatite material (cortical bovine femur) and two synthetic hydroxyapatite-based materials with biomimetic structures-a hydroxyapatite skeleton interpenetrated with a metallic (silver) or a polymeric (nylon-6) phase. In both the natural and synthetic materials, a conspicuous amount of toughening arose from a microscopic crack-bridging mechanism operated by elasto-plastic stretching of unbroken second-phase ligaments along the crack wake. This mechanism led to a rising R-curve behavior. An additional micromechanism, responsible for stress relaxation at the crack tip, was recognized in the natural bone material and was partly mimicked in the hydroxyapatite/silver composite. This crack-tip mechanism conspicuously enhanced the cortical bone material resistance to fracture initiation. A piezo-spectroscopic technique, based on a microprobe measurement of 980 cm(-1) Raman line of hydroxyapatite, enabled us to quantitatively assess in situ the microscopic stress fields developed during fracture both at the crack tip and along the crack wake. Using the Raman piezo-spectroscopy technique, toughening mechanisms were assessed quantitatively and rationally related to the macroscopic fracture characteristics of hydroxyapatite-based materials. Copyright 2003 Wiley Periodicals, Inc.

  11. Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates

    Directory of Open Access Journals (Sweden)

    Alexander J. Knowles

    2017-10-01

    Full Text Available The data presented in this article are related to the research article entitled “Laves phase intermetallic matrix composite in situ toughened by ductile precipitates” (Knowles et al. [1]. The composite comprised a Fe2(Mo, Ti matrix with bcc (Mo, Ti precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al. [1]. Here, details are given on a focused ion beam (FIB slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al. [1] along with details of the transformation matrix determined.

  12. Promoter scanning of the human COX-2 gene with 8-ring polyamides: unexpected weakening of polyamide-DNA binding and selectivity by replacing an internal N-Me-pyrrole with β-alanine.

    Science.gov (United States)

    Bashkin, James K; Aston, Karl; Ramos, Joseph P; Koeller, Kevin J; Nanjunda, Rupesh; He, Gaofei; Dupureur, Cynthia M; David Wilson, W

    2013-02-01

    Rules for polyamide-DNA recognition have proved invaluable for the design of sequence-selective DNA binding agents in cell-free systems. However, these rules are not fully transferrable to predicting activity in cells, tissues or animals, and additional refinements to our understanding of DNA recognition would help biomedical studies. Similar complexities are encountered when using internal β-alanines as polyamide building blocks in place of N-methylpyrrole; β-alanines were introduced in polyamide designs to maintain good hydrogen bonding registry with the target DNA, especially for long polyamides or those with several GC bp (P.B. Dervan, A.R. Urbach, Essays Contemp. Chem. (2001) 327-339). Thus, to clarify important subtleties of molecular recognition, we studied the effects of replacing a single pyrrole with β-alanine in 8-ring polyamides designed against the Ets-1 transcription factor. Replacement of a single internal N-methylpyrrole with β-alanine to generate a β/Im pairing in two 8-ring polyamides causes a decrease in DNA binding affinity by two orders of magnitude and decreases DNA binding selectivity, contrary to expectations based on the literature. Measurements were made by fluorescence spectroscopy, quantitative DNA footprinting and surface plasmon resonance, with these vastly different techniques showing excellent agreement. Furthermore, results were validated for a range of DNA substrates from small hairpins to long dsDNA sequences. Docking studies helped show that β-alanine does not make efficient hydrophobic contacts with the rest of the polyamide or nearby DNA, in contrast to pyrrole. These results help refine design principles and expectations for polyamide-DNA recognition. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  13. Hybrid Carbon-Glass Fiber/Toughened Epoxy Thick Composite Joints Subject to Drop-Weight and Ballistic Impacts

    National Research Council Canada - National Science Library

    Liaw, Benjamin; Delale, Feridun

    2007-01-01

    ... No. DAAD19-02-R-0010 to conduct research on hybrid carbon-S2 glass fiber/toughened epoxy thick-section, hybrid interwoven composite joints subject to drop-weight and ballistic impacts. Dr. Basavaraju B. Raju of U.S...

  14. The phase stability and toughening effect of 3Y-TZP dispersed in the lanthanum zirconate ceramics

    International Nuclear Information System (INIS)

    Wang, Yanfei; Xiao, Ping

    2014-01-01

    The low fracture toughness of lanthanum zirconate (La 2 Zr 2 O 7 , LZ) greatly impedes its wide application as thermal barrier coatings (TBC). The 3 mol% Y 2 O 3 -stabilized tetragonal zirconia polycrystals (3Y-TZP) have been introduced to toughen the brittle LZ ceramics. The dispersive 3Y-TZP undergoes a simultaneous t–m transformation upon cooling below a critical volume fraction x of 3Y-TZP, above which its tetragonal phases can however be preserved. The different stabilities of 3Y-TZP second phases arise from a variation of residual tensile stress within them. The fracture toughness has been greatly improved by dispersing the tetragonal particulates (t-3YSZ) in the LZ matrix and the primary toughening mechanisms are phase transformations of the dispersive second phases and the residual compressive stress within the matrix. An anticipated increase of fracture toughness from the ferroelastic toughening and the residual compressive stress toughening highlights the great potentials to improve coating durability by depositing t′-3YSZ/LZ composite TBCs by the industrial non-equilibrium route

  15. High-performance polyamide thin-film-nanocomposite reverse osmosis membranes containing hydrophobic zeolitic imidazolate framework-8

    KAUST Repository

    Duan, Jintang; Pan, Yichang; Pacheco Oreamuno, Federico; Litwiller, Eric; Lai, Zhiping; Pinnau, Ingo

    2015-01-01

    A hydrophobic, hydrothermally stable metal-organic framework (MOF) - zeolitic imidazolate framework-8 (ZIF-8) was successfully incorporated into the selective polyamide (PA) layer of thin-film nanocomposite (TFN) membranes for water desalination

  16. UV excimer laser and low temperature plasma treatments of polyamide materials

    Science.gov (United States)

    Yip, Yiu Wan Joanne

    Polyamides have found widespread application in various industrial sectors, for example, they are used in apparel, home furnishings and similar uses. However, the requirements for high quality performance products are continually increasing and these promote a variety of surface treatments for polymer modification. UV excimer laser and low temperature plasma treatments are ideally suited for polyamide modification because they can change the physical and chemical properties of the material without affecting its bulk features. This project aimed to study the modification of polyamides by UV excimer laser irradiation and low temperature plasma treatment. The morphological changes in the resulting samples were analysed by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM-AFM). The chemical modifications were studied by x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and chemical force microscopy (CFM). Change in degree of crystallinity was examined by differential scanning calorimetry (DSC). After high-fluence laser irradiation, topographical results showed that ripples of micrometer size form on the fibre surface. By contrast, sub-micrometer size structures form on the polyamide surface when the applied laser energy is well below its ablation threshold. After high-fluence laser irradiation, chemical studies showed that the surface oxygen content of polyamide is reduced. A reverse result is obtained with low-fluence treatment. The DSC result showed no significant change in degree of crystallinity in either high-fluence or low-fluence treated samples. The same modifications in polyamide surfaces were studied after low temperature plasma treatment with oxygen, argon or tetrafluoromethane gas. The most significant result was that the surface oxygen content of polyamide increased after oxygen and argon plasma treatments. Both treatments induced many hydroxyl (-OH) and carboxylic acid (-COOH

  17. Electronic properties of polyamide-PPy/metal junction and electrical conductivity of a typical sample at low temperatures

    International Nuclear Information System (INIS)

    Suenel, N.; Sedef, A.G.; Parlak, M.; Toppare, L.

    2005-01-01

    Electronic properties of junctions fabricated by polyamide-polypyrrole composite films polymerized with adjusted doping concentration and various metal contacts (In, Al, Au and Ag) were investigated. For the junctions giving good rectification I 0 , n and φ b were specified. Conductivity of polyamide-polypyrrole composite polymer was obtained as a function of temperature in the 70-320 K range and was found to obey the VRH model. In addition the Mott parameters were evaluated

  18. Electronic properties of polyamide-PPy/metal junction and electrical conductivity of a typical sample at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Suenel, N. [Gaziosmanpasa University, Physics Department, Tasliciftlik Kampasu, Tokat (Turkey)]. E-mail: nsunel@gop.edu.tr; Sedef, A.G. [Gaziosmanpasa University, Physics Department, Tasliciftlik Kampasu, Tokat (Turkey); Parlak, M. [Middle East Technical University, Physics Department, Ankara (Turkey); Toppare, L. [Middle East Technical University, Chemistry Department, Ankara (Turkey)

    2005-05-15

    Electronic properties of junctions fabricated by polyamide-polypyrrole composite films polymerized with adjusted doping concentration and various metal contacts (In, Al, Au and Ag) were investigated. For the junctions giving good rectification I{sub 0}, n and {phi}{sub b} were specified. Conductivity of polyamide-polypyrrole composite polymer was obtained as a function of temperature in the 70-320 K range and was found to obey the VRH model. In addition the Mott parameters were evaluated.

  19. Preparation and Characterization of Polyurethane-Polydimethylsiloxane/Polyamide12-b-Polytetramethylene Glycol Blend Membranes for Gas Separation

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Semsarzadeh*

    2013-07-01

    Full Text Available Blend membranes of synthesized polyurethane based on toluene diisocyanate (TDI, polydimethylsiloxane (PDMS and polytetramethylene glycol (PTMG with polyamide12-b-PTMG were prepared by solution casting technique. The synthesized polyurethane-polydimethylsiloxane and PU-PDMS/polyamide12-b-PTMG blend membranes were characterized by Fourier transform infrared spectroscopy (FTIR, differential scanning calorimetry (DSC and scanning electron microscopy (SEM. In the FTIR spectrum of the synthesized PU-PDMS, the disappearance of NCO stretching vibration at 2270 cm−1 was used to confirm the completion of the reaction. According to our DSC results, the use of higher polyamide12-b-PTMG content in PU-PDMS/polyamide12-b-PTMG blends led to greater compatibility between the two phases. The SEM images showed that the blends with polyamide12-b-PTMG (20 wt% were significantly more homogeneous in the micrometric scale compared to other samples. Gas transport properties have been determined for N2, CO2 and He gases and the obtained permeability values were correlated with the properties of the blends. The comparison of the results with that of the pure PU-PDMS membrane showed that the blend membranes had a higher permeability toward CO2 and lower toward N2 gas. The blend membrane with 20 wt% polyamide12-b-PTMG showed higher CO2 permeability (≈105 Barrer compared to PU-PDMS membrane. By introduction of polyamide12-b-PTMG into PU-PDMS matrix a perceptible rise in helium ideal selectivity of the blend membranes was observed. In blend membranes with 5-20 wt% polyamide12-b-PTMG contents, an enhancement of CO2/N2 (244%, He/N2 (20% and CO2/He (103% selectivity factor was observed. The experimental permeability values of the blend membranes were compared with the calculated permeability based on a modified additive logarithmic model.

  20. Multi-scale modelling of non-uniform consolidation of uncured toughened unidirectional prepregs

    Science.gov (United States)

    Sorba, G.; Binetruy, C.; Syerko, E.; Leygue, A.; Comas-Cardona, S.; Belnoue, J. P.-H.; Nixon-Pearson, O. J.; Ivanov, D. S.; Hallett, S. R.; Advani, S. G.

    2018-05-01

    Consolidation is a crucial step in manufacturing of composite parts with prepregs because its role is to eliminate inter- and intra-ply gaps and porosity. Some thermoset prepreg systems are toughened with thermoplastic particles. Depending on their size, thermoplastic particles can be either located in between plies or distributed within the inter-fibre regions. When subjected to transverse compaction, resin will bleed out of low-viscosity unidirectional prepregs along the fibre direction, whereas one would expect transverse squeeze flow to dominate for higher viscosity prepregs. Recent experimental work showed that the consolidation of uncured toughened prepregs involves complex flow and deformation mechanisms where both bleeding and squeeze flow patterns are observed [1]. Micrographs of compacted and cured samples confirm these features as shown in Fig.1. A phenomenological model was proposed [2] where bleeding flow and squeeze flow are combined. A criterion for the transition from shear flow to resin bleeding was also proposed. However, the micrographs also reveal a resin rich layer between plies which may be contributing to the complex flow mechanisms during the consolidation process. In an effort to provide additional insight into these complex mechanisms, this work focuses on the 3D numerical modelling of the compaction of uncured toughened prepregs in the cross-ply configuration described in [1]. A transversely isotropic fluid model is used to describe the flow behaviour of the plies coupled with interplay resin flow of an isotropic fluid. The multi-scale flow model used is based on [3, 4]. A numerical parametric study is carried out where the resin viscosity, permeability and inter-ply thickness are varied to identify the role of important variables. The squeezing flow and the bleeding flow are compared for a range of process parameters to investigate the coupling and competition between the two flow mechanisms. Figure 4 shows the predicted displacement of

  1. Prototype evaluation of transformation toughened blast resistant naval hull steels: Part II

    Science.gov (United States)

    Saha, A.; Jung, J.; Olson, G. B.

    2007-07-01

    Application of a systems approach to computational materials design led to the theoretical design of a transformation toughened ultratough high-strength plate steel for blast-resistant naval hull applications. A first prototype alloy has achieved property goals motivated by projected naval hull applications requiring extreme fracture toughness (C v > 85 ft-lbs or 115 J corresponding to K Id≥ 200 ksi.in1/2 or 220 MPa.m1/2) at strength levels of 150 180 ksi (1,030 1,240 MPa) yield strength in weldable, formable plate steels. A continuous casting process was simulated by slab casting the prototype alloy as a 1.75‧‧ (4.45 cm) plate. Consistent with predictions, compositional banding in the plate was limited to an amplitude of 6 7.5 wt% Ni and 3.5 5 wt% Cu. Examination of the oxide scale showed no evidence of hot shortness in the alloy during hot working. Isothermal transformation kinetics measurements demonstrated achievement of 50% bainite in 4 min at 360 °C. Hardness and tensile tests confirmed predicted precipitation strengthening behavior in quench and tempered material. Multi-step tempering conditions were employed to achieve the optimal austenite stability resulting in significant increase of impact toughness to 130 ft-lb (176 J) at a strength level of 160 ksi (1,100 MPa). Comparison with the baseline toughness strength combination determined by isochronal tempering studies indicates a transformation toughening increment of 65% in Charpy energy. Predicted Cu particle number densities and the heterogeneous nucleation of optimal stability high Ni 5 nm austenite on nanometer-scale copper precipitates in the multi-step tempered samples was confirmed using three-dimensional atom probe microanalysis. Charpy impact tests and fractography demonstrate ductile fracture with C v > 80 ft-lbs (108 J) down to -40 °C, with a substantial toughness peak at 25 °C consistent with designed transformation toughening behavior. The properties demonstrated in this first

  2. Mixed field radiation effects on dry and acidic solution saturated polyamide 6,6

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ont., K7K 7B4 (Canada); Bonin, H.W. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ont., K7K 7B4 (Canada)]. E-mail: bonin-h@rmc.ca; Bui, V.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ont., K7K 7B4 (Canada)

    2005-05-15

    The disposal of Canada's radioactive waste materials has been the focus of ongoing research at the Royal Military College of Canada, in the use of polymer-based composite materials for the fabrication of disposal containers. An evaluation of the performance of polyamide 6,6 after exposure to radiation and acidic aqueous solutions provides the basis for the assessment of the lifetime performance of a polymeric-based storage container. This work demonstrates the importance of the combined effects of aqueous solution diffusion and radiation exposure on the mechanical performance and molecular structure of polyamide 6,6. Irradiation of dry samples initially results in a marked reduction of mechanical performance, however, post-irradiation aging allows for the return to pre-irradiation mechanical strength. Samples irradiated after exposure to either distilled water or 0.1 M sulfuric acid solutions exhibited increases in mechanical performance upon exposure to a mixed field radioactive environment.

  3. Mixed field radiation effects on dry and acidic solution saturated polyamide 6,6

    International Nuclear Information System (INIS)

    Brown, L.; Bonin, H.W.; Bui, V.T.

    2005-01-01

    The disposal of Canada's radioactive waste materials has been the focus of ongoing research at the Royal Military College of Canada, in the use of polymer-based composite materials for the fabrication of disposal containers. An evaluation of the performance of polyamide 6,6 after exposure to radiation and acidic aqueous solutions provides the basis for the assessment of the lifetime performance of a polymeric-based storage container. This work demonstrates the importance of the combined effects of aqueous solution diffusion and radiation exposure on the mechanical performance and molecular structure of polyamide 6,6. Irradiation of dry samples initially results in a marked reduction of mechanical performance, however, post-irradiation aging allows for the return to pre-irradiation mechanical strength. Samples irradiated after exposure to either distilled water or 0.1 M sulfuric acid solutions exhibited increases in mechanical performance upon exposure to a mixed field radioactive environment

  4. Preparation and characterization of new polyamide/montmorillonite nanocomposites containing azo moiety in the main chain

    Directory of Open Access Journals (Sweden)

    Khalil Faghihi

    2016-11-01

    Full Text Available Two new samples of polyamide/montmorillonite reinforced nanocomposites containing 4,4′-azobenzoic acid moiety in the main chain were synthesized by a convenient solution intercalation technique. Polyamide (PA 4 as a source of polymer matrix was synthesized by the direct polycondensation reaction of 4,4′-azobenzoic acid 2 with 4,4′-diamino diphenyl ether 3 in the presence of triphenyl phosphite (TPP, CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP. Morphology and structure of the resulting PA-nanocomposite films 4a and 4b with 10 and 20% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposites films were investigated by using UV–vis spectroscopy, thermogravimetric analysis (TGA and water uptake measurements.

  5. Synthesis and Thermal and Photo Behaviors of New Polyamide/Organocaly Nanocomposites Containing Para Phenylenediacrylic Moiety

    Science.gov (United States)

    Faghihi, Khalil; Soleimani, Masoumeh; Shabanian, Meisam; Abootalebi, Ashraf Sadat

    2011-06-01

    New type of aromatic polyamide/montmorillonite nanocomposites were produced using solution process in N-methyl-2-pyrolidone. Amide chains were synthesized from 4,4'-diaminodiphenyl sulfone and p-phenylenediacrylic acid in N-methyl-2-pyrolidone. The resulting nanocomposite films containing 5-15 mass % of organoclay were characterized for FT-IR, scanning electronmicroscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), optical transparency and water absorption measurements. The distribution of organoclay and nanostructure of the composites were investigated by (XRD) and SEM analyses. Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. The percentage optical transparency and water absorption of these hybrids was found to be much reduced upon the addition of modified layered silicate indicating decreased permeability.

  6. Evaluation of rheological behavior and structure of nanocomposites with polymer matrices of polyamide 6 and polyethylene

    International Nuclear Information System (INIS)

    Cavalcanti, Shirley N.; Araujo, Edcleide M.; Paz, Rene A.; Gouveia, Taciana R.; Oliveira, Sara V.; Souza, Dayanne D. de

    2009-01-01

    The objective of this study was to evaluate the results of the obtention of nanocomposites from the system of high density polyethylene (PEAD)/polyamide 6/organoclay, using concentrations of (5 and 10wt.%) compatibilizer PE-g-MA, the organoclay was organophilizate with the quaternary ammonium salt Genamin and mixtures were prepared in a twin screw counter rotating extruder, coupled to a Haake torque rheometer. The rheological behavior of the blends and the nanocomposites was evaluated by torque rheometer. The degree of dispersion of clay in the blend (polyamide 6 and PE) was evaluated by x-ray diffraction (XRD). In general, it was observed an increase in viscosity for the compositions containing the compatibilizer, and the results of XRD showed that the systems presented an intercalated and/or exfoliated structure. (author)

  7. Preparation and Characterization of Silica/Polyamide-imide Nanocomposite Thin Films

    Directory of Open Access Journals (Sweden)

    Hwang Jong-Sun

    2010-01-01

    Full Text Available Abstract The functional silica/polyamide-imide composite films were prepared via simple ultrasonic blending, after the silica nanoparticles were modified by cationic surfactant—cetyltrimethyl ammonium bromide (CTAB. The composite films were characterized by scanning electron microscope (SEM, thermo gravimetric analysis (TGA and thermomechanical analysis (TMA. CTAB-modified silica nanoparticles were well dispersed in the polyamide-imide matrix, and the amount of silica nanoparticles to PAI was investigated to be from 2 to 10 wt%. Especially, the coefficients of thermal expansion (CET continuously decreased with the amount of silica particles increasing. The high thermal stability and low coefficient of thermal expansion showed that the nanocomposite films can be widely used in the enamel wire industry.

  8. Control of the interfacial reactions in Nb-toughened MoSi2

    International Nuclear Information System (INIS)

    Shaw, L.; Abbaschian, R.

    1993-01-01

    Toughening of MoSi 2 for high-temperature applications can be achieved by incorporating ductile refractory-metal reinforcements, provided that a coating is applied to prevent interdiffusion and reaction between the matrix and the reinforcements. In the present study, three different coating techniques for applying a thin Al 2 O 3 film on Nb reinforcements as a diffusion barrier have been studied. The techniques consisted of (1) sol-gel coating; (2) physical vapor deposition (PVD); (3) hot dipping in molten Al, followed by anodizing Al to form Al 2 O 3 . The processing parameters for the techniques were evaluated and the effectiveness of each coating as a diffusion barrier was assessed. For the present MoSi 2 matrix which contains SiO 2 , PVD coatings provided the most effective diffusion barrier for processing MoSi 2 /Nb composites

  9. The influence of gamma radiation on the ESC behaviour of a toughened PMMA through stress relaxation

    International Nuclear Information System (INIS)

    Sousa, Alexandre R.; Araujo, Elmo S.; Rabello, Marcelo S.

    2009-01-01

    On this work we studied the ESC degradation behaviour of a toughened PMMA irradiated with different gamma radiation doses. Tensile samples were obtained by injection moulding, and then irradiated using a 60 Co source. The samples irradiated on several doses were submitted to relaxation tests under air, ethanol and ethylene glycol. The results showed that the ESC action was intensified with the rising radiation doses when the relaxation tests were done under ethanol. On the tests under ethylene glycol the ESC effect was observed only to the irradiated polymer through the higher dose and under the higher relaxation load. The fracture surface analysis of tested relaxation samples, under ethanol, showed a dendritic pattern formed on fracture surfaces. (author)

  10. Toughening of carbon fibre reinforced polymer composites with rubber nanoparticles for advanced industrial applications

    Directory of Open Access Journals (Sweden)

    N. G. Ozdemir

    2016-05-01

    Full Text Available This study investigates the effects of nano carboxylic acrylonitrile butadiene rubber (CNBR-NP and nano acrylonitrile butadiene rubber (NBR-NP on the interlaminar shear strength and fracture toughness of carbon fibre reinforced polymer composites (CFRP with dicyandiamide-cured epoxy matrix. The results show that nano-size dispersion of rubber significantly improved the Mode I delamination fracture toughness (GIC of the CFRP by 250% and its Mode II delamination fracture toughness (GIIC by 80% with the addition of 20 phr of CNBR-NP. For the NBR-NP system, the GIC and GIIC delamination fracture toughness of the CFRP were increased by 200 and 80% respectively with the addition of 20 phr (parts per hundred rubber of nano rubber to the matrix. Scanning electron microscopy (SEM images of the fracture surface revealed that the toughening was mainly achieved by debonding of the nano rubber, crack path deflection and fibre bridging.

  11. Tablet-level origin of toughening in abalone shells and translation to synthetic composite materials.

    Science.gov (United States)

    Espinosa, Horacio D; Juster, Allison L; Latourte, Felix J; Loh, Owen Y; Gregoire, David; Zavattieri, Pablo D

    2011-02-01

    Nacre, the iridescent material in seashells, is one of many natural materials employing hierarchical structures to achieve high strength and toughness from relatively weak constituents. Incorporating these structures into composites is appealing as conventional engineering materials often sacrifice strength to improve toughness. Researchers hypothesize that nacre's toughness originates within its brick-and-mortar-like microstructure. Under loading, bricks slide relative to each other, propagating inelastic deformation over millimeter length scales. This leads to orders-of-magnitude increase in toughness. Here, we use in situ atomic force microscopy fracture experiments and digital image correlation to quantitatively prove that brick morphology (waviness) leads to transverse dilation and subsequent interfacial hardening during sliding, a previously hypothesized dominant toughening mechanism in nacre. By replicating this mechanism in a scaled-up model synthetic material, we find that it indeed leads to major improvements in energy dissipation. Ultimately, lessons from this investigation may be key to realizing the immense potential of widely pursued nanocomposites.

  12. Studies of LENRA-Toughened PVC non-woven membranes prepared by electro spinning technique

    International Nuclear Information System (INIS)

    Dahlan Mohd; Mahathir Mohamed; Khirul Hafiz mohd Yusof

    2010-01-01

    Lately research in use of so-called green chemicals draws strong interest from research community due to the climate change issues. Malaysia is in strong position to take this advantage because we are among the world biggest producers of natural rubber and palm oil - the two sources of important green renewable chemical feedstock in the near future. For the last couple of years we have shown how modified natural rubbers especially liquid natural rubber and its derivatives such as liquid epoxidized natural rubber acrylate (LENRA) could be used in various applications via among others sol-gel technique and radiation curing technology. This time around we will show another application on how non-woven membranes made from PVC can be prepared by electro spinning technique using radiation curable LENRA as toughener. The electro spinning technique has great potential in producing nano fiber materials to be used in various applications to ensure sustainable energy and environments for the future. (author)

  13. Enhancing the cellular uptake of Py–Im polyamides through next-generation aryl turns

    OpenAIRE

    Meier, Jordan L.; Montgomery, David C.; Dervan, Peter B.

    2012-01-01

    Pyrrole–imidazole (Py–Im) hairpin polyamides are a class of programmable, sequence-specific DNA binding oligomers capable of disrupting protein–DNA interactions and modulating gene expression in living cells. Methods to control the cellular uptake and nuclear localization of these compounds are essential to their application as molecular probes or therapeutic agents. Here, we explore modifications of the hairpin γ-aminobutyric acid turn unit as a means to enhance cellular uptake and biologica...

  14. Study of the effect of ionizing radiation on properties of polyamide 6 with fibreglass reinforcement

    International Nuclear Information System (INIS)

    Pinto, Clovis

    2007-01-01

    It is each time more common the use of polymers reinforced with fibreglass in the domestic market. Between them it is used polyamide 6 that it presents good tension resistance, to the impact and the humidity absorption compared with non-reinforced, being also at the present time used in the automobile industry in parts underneath the hood, especially in the radiator frames. The aim of this work is to study the effect of ionizing radiation on properties of polyamide 6 with fibreglass reinforcement, undergone to different radiation doses. Samples were prepared and irradiated on JOB 188 accelerator with an electron beam energy of 1.5 MeV in air with different doses (100 to 600 kGy) and a dose rate of 22.61 kGy/h. Afterward the irradiation, the properties of the samples of irradiated polyamide 6 with fibreglass reinforcement were evaluated and compared with the samples non-irradiated. It evidenced that the mechanical properties flexural resistance and tension resistance increased and the resistance to the impact decreased. Regarding the thermal properties of the temperature of fusing decreased of 224,4 deg C for 212,5 deg C but the loss of mass ahead of the constant increase of the temperature also decreased. In the property of resistance to the glow wire the polyamide 6 with fibreglass reinforcement had a good performance. The images caught for Scanning Electronic Microscopy show that the irradiation provoked a good integration enters the fibreglass and polymer what was responsible for the good performance in the property of resistance to the glow wire. (author)

  15. Effect of graphene oxide on structure and properties of impact-modified polyamide 6

    Czech Academy of Sciences Publication Activity Database

    Kelnar, Ivan; Kratochvíl, Jaroslav; Kaprálková, Ludmila; Špitálsky, Z.; Ujčić, Massimo; Zhigunov, Alexander; Nevoralová, Martina

    2018-01-01

    Roč. 57, č. 9 (2018), s. 827-835 ISSN 0360-2559 R&D Projects: GA ČR(CZ) GA16-03194S Institutional support: RVO:61389013 Keywords : graphene oxide * morphology * polyamide 6 Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 1.232, year: 2016

  16. Study of nanocomposites prepared from polyamides and biodegradable polyesters and poly(ester amide)s

    OpenAIRE

    Morales Gámez, Laura Teresa

    2012-01-01

    Premi extraordinari doctorat curs 2011-2012, àmbit d’Enginyeria Industrial Polymer clay nanocomposites of polyamides and biodegradable polymers with three kinds of organomodified clays were prepared by different techniques (in situ polymerization, solution casting, and melt mixing). The polymers used in this research were nylons 56, 65 and 47 and the biodegradable polymers: poly (glycolic acid-alt-6-hydrohexanoic acid) and poly(glycolic acid-alt-6-aminohexanoic acid). The developmen...

  17. An electron beam irradiation method for modification of surface electrical resistivity of polyamides

    International Nuclear Information System (INIS)

    Brasoveanu, M. M.; Timus, D.; Nemtanu, M. R.

    2002-01-01

    The synthetic textiles which have mechanical and processing properties and a low price are very useful and consequently in high demand. The low antistatic qualities are an important disadvantage, but not impossible to eliminate. The aim of paper is the study of modification the antistatic properties of polyamide by grafting of monomers by irradiation. Twisted and unthermofixed polyamide-6 fibre from CFS Savinesti were investigated. The samples of polyamide were irradiated with an electron beam from the ALIN-7 linear accelerator of Electron Accelerators Laboratory of National Institute for Lasers, Plasma and Radiation Physics, Bucharest. Immediately after irradiation, the samples were measured by electron spin resonance (ESR). ESR spectra were recorded at room temperature using a Jeol spectrometer, JES-ME-3X, with 100 kHz modulation. In polyamide-6 at least two irradiation defect types occurred which present EPR signal by electron beam irradiation. Unstable centres of type A presenting an incompletely resolved hyperfine structure can be attributed to radicals -N-CH 2 - or -NH-CH-CH 2 -. Both radicals can present at room temperature a five-line spectrum like the radical formed in this work. First radical appears with very low probability and if the free bond is at one of carbon atoms then it will be stabilized immediately in a position from nitrogen. These type A radicals can appear in same zone and then they can react and form unsaturated bonds or bridge between the polymeric chains. Thus, it will appear the type B defects which were more stabile and without structure. On these double chains one can graft vinylic monomers even after time intervals longer from irradiation. (authors)

  18. Reuse of effluent from dyeing process of polyamide fibers modified by double barrier discharge (DBD) plasma

    OpenAIRE

    Oliveira, Fernando Ribeiro; Steffens, F.; Souto, A. Pedro; Zille, Andrea

    2016-01-01

    Published online: 27 Feb 2015 Low-temperature plasma technology becomes more and more attractive compared with traditional wet processes in textile preparation and finishing due to its high efficiency and low environmental impact. The objective of this study was to investigate the influence of dielectric barrier discharge plasma treatment on the trichromic dyeing process of polyamide 6.6 (PA66) and the reuse of the generated effluents for new dyeing processes. Chemical and physical charact...

  19. Optimization of preparation conditions of polyamide thin film composite membrane for organic solvent nanofiltration

    International Nuclear Information System (INIS)

    Namvar-Mahboub, Mahdieh; Pakizeh, Majid

    2014-01-01

    Separation performance of polyamide composite membranes is affected by several parameters during formation of thin upper layer via interfacial polymerization. We investigated the effect of various polyamide synthesis conditions on the performance of organic solvent resistant polyamide composite membranes through the model equations designed by 2-level fractional factorial design. The dewaxing solvent recovery was selected as separation process. Five factors were changed in two level includin; TMC concentration (0.05-0.1%), MPD concentration (1-2%), support immersion time in organic solution (2-4 min), support immersion time in aqueous solution (1-2 min), and curing temperature (70-80 .deg. C). The resultant equations showed 93.48% and 94.82% of the variability (R 2 adj ) in data used to fit oil rejection and permeate flux models, respectively. The analysis of variance revealed that both models were high significant. It was also observed that TMC concentration, MPD concentration and immersion time in TMC have more pronounced effect on the oil rejection and permeate flux than other factors and interactions. Optimal polyamide preparation conditions were obtained using multiple response method for 94% oil rejection as target value. According to the results, the best value of permeate flux (8.86 l/(m 2 ·h)) was found at TMC concentration of 0.1%, MPD concentration of 1.94%, immersion time in TMC of 3.88 min, immersion time in MPD of 1.95 min and curing temperature of 71.96 .deg. C with desirability factor of 1

  20. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    International Nuclear Information System (INIS)

    Feng, Pei; Wei, Pingpin; Li, Pengjian; Gao, Chengde; Shuai, Cijun; Peng, Shuping

    2014-01-01

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m 1/2 ) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability

  1. Static and dynamic strain energy release rates in toughened thermosetting composite laminates

    Science.gov (United States)

    Cairns, Douglas S.

    1992-01-01

    In this work, the static and dynamic fracture properties of several thermosetting resin based composite laminates are presented. Two classes of materials are explored. These are homogeneous, thermosetting resins and toughened, multi-phase, thermosetting resin systems. Multi-phase resin materials have shown enhancement over homogenous materials with respect to damage resistance. The development of new dynamic tests are presented for composite laminates based on Width Tapered Double Cantilevered Beam (WTDCB) for Mode 1 fracture and the End Notched Flexure (ENF) specimen. The WTDCB sample was loaded via a low inertia, pneumatic cylinder to produce rapid cross-head displacements. A high rate, piezo-electric load cell and an accelerometer were mounted on the specimen. A digital oscilloscope was used for data acquisition. Typical static and dynamic load versus displacement plots are presented. The ENF specimen was impacted in three point bending with an instrumented impact tower. Fracture initiation and propagation energies under static and dynamic conditions were determined analytically and experimentally. The test results for Mode 1 fracture are relatively insensitive to strain rate effects for the laminates tested in this study. The test results from Mode 2 fracture indicate that the toughened systems provide superior fracture initiation and higher resistance to propagation under dynamic conditions. While the static fracture properties of the homogeneous systems may be relatively high, the apparent Mode 2 dynamic critical strain energy release rate drops significantly. The results indicate that static Mode 2 fracture testing is inadequate for determining the fracture performance of composite structures subjected to conditions such as low velocity impact. A good correlation between the basic Mode 2 dynamic fracture properties and the performance is a combined material/structural Compression After Impact (CAI) test is found. These results underscore the importance of

  2. Three-dimensional deformation mapping of Mode I interlaminar crack extension in particle-toughened interlayers

    International Nuclear Information System (INIS)

    Borstnar, G.; Gillard, F.; Mavrogordato, M.N.; Sinclair, I.; Spearing, S.M.

    2016-01-01

    This paper presents the first use of Digital Volume Correlation (DVC) on Carbon Fibre Reinforced Plastics (CFRPs) to quantify the strain fields ahead of a Mode I delamination. DVC is a relatively novel tool that can be used to measure displacements and strains occurring inside materials under load. In conjunction with Computed Tomography (CT), the technique has been applied to porous materials, with results providing strain data for validation of Finite Element (FE) models. However, the application of the technique to laminated materials has been limited, with studies often requiring fiducial markings required for volume correlation. In this work, crack propagation steps were captured at a 325 nm voxel resolution using Synchrotron Radiation Computed Tomography (SRCT). The material systems investigated featured different crack bridging mechanisms such as; particle-bridges, resin ligaments, and fibre-bridges. An assessment of noise and sub-volume size on the strain measurement determined that the optimal sub-volume size was 150 voxels with 50% overlap. This provided a spatial resolution of 48.8 μm for strain and a corresponding strain resolution ranging between 220 and 690 με for the repeated reference scans. A rigid body translation study confirmed that specimen movements perpendicular to the fibre orientation support the ‘real’ physical displacements. However, along the fibre direction, the correlation was poor, with correct displacements being detected only within the particle-toughened interlayers. The study demonstrates that strain measurements can be made perpendicular to the fibre direction across the interlayer, which could be used to validate future FE models of these poorly understood particle-toughened interlayers.

  3. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Pei [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Wei, Pingpin [Cancer Research Institute, Central South University, Changsha 410078 (China); Li, Pengjian; Gao, Chengde [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Shuai, Cijun, E-mail: shuai@csu.edu.cn [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425 (United States); Peng, Shuping, E-mail: shuping@csu.edu.cn [Cancer Research Institute, Central South University, Changsha 410078 (China)

    2014-11-15

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

  4. Selective etching of injection molded zirconia-toughened alumina: Towards osseointegrated and antibacterial ceramic implants.

    Science.gov (United States)

    Flamant, Quentin; Caravaca, Carlos; Meille, Sylvain; Gremillard, Laurent; Chevalier, Jérôme; Biotteau-Deheuvels, Katia; Kuntz, Meinhard; Chandrawati, Rona; Herrmann, Inge K; Spicer, Christopher D; Stevens, Molly M; Anglada, Marc

    2016-12-01

    Due to their outstanding mechanical properties and excellent biocompatibility, zirconia-toughened alumina (ZTA) ceramics have become the gold standard in orthopedics for the fabrication of ceramic bearing components over the last decade. However, ZTA is bioinert, which hampers its implantation in direct contact with bone. Furthermore, periprosthetic joint infections are now the leading cause of failure for joint arthroplasty prostheses. To address both issues, an improved surface design is required: a controlled micro- and nano-roughness can promote osseointegration and limit bacterial adhesion whereas surface porosity allows loading and delivery of antibacterial compounds. In this work, we developed an integrated strategy aiming to provide both osseointegrative and antibacterial properties to ZTA surfaces. The micro-topography was controlled by injection molding. Meanwhile a novel process involving the selective dissolution of zirconia (selective etching) was used to produce nano-roughness and interconnected nanoporosity. Potential utilization of the porosity for loading and delivery of antibiotic molecules was demonstrated, and the impact of selective etching on mechanical properties and hydrothermal stability was shown to be limited. The combination of injection molding and selective etching thus appears promising for fabricating a new generation of ZTA components implantable in direct contact with bone. Zirconia-toughened alumina (ZTA) is the current gold standard for the fabrication of orthopedic ceramic components. In the present work, we propose an innovative strategy to provide both osseointegrative and antibacterial properties to ZTA surfaces: we demonstrate that injection molding allows a flexible design of surface micro-topography and can be combined with selective etching, a novel process that induces nano-roughness and surface interconnected porosity without the need for coating, avoiding reliability issues. These surface modifications have the

  5. Sub-10-micrometer toughening and crack tip toughness of dental enamel.

    Science.gov (United States)

    Ang, Siang Fung; Schulz, Anja; Pacher Fernandes, Rodrigo; Schneider, Gerold A

    2011-04-01

    In previous studies, enamel showed indications to occlude small cracks in-vivo and exhibited R-curve behaviors for bigger cracks ex-vivo. This study quantifies the crack tip's toughness (K(I0),K(III0)), the crack's closure stress and the cohesive zone size at the crack tip of enamel and investigates the toughening mechanisms near the crack tip down to the length scale of a single enamel crystallite. The crack-opening-displacement (COD) profile of cracks induced by Vickers indents on mature bovine enamel was studied using atomic force microscopy (AFM). The mode I crack tip toughness K(I0) of cracks along enamel rod boundaries and across enamel rods exhibit a similar range of values: K(I0,Ir)=0.5-1.6MPa m(0.5) (based on Irwin's 'near-field' solution) and K(I0,cz)=0.8-1.5MPa m(0.5) (based on the cohesive zone solution of the Dugdale-Muskhelishvili (DM) crack model). The mode III crack tip toughness K(III0,Ir) was computed as 0.02-0.15MPa m(0.5). The crack-closure stress at the crack tip was computed as 163-770 MPa with a cohesive zone length and width 1.6-10.1μm and 24-44 nm utilizing the cohesive zone solution. Toughening elements were observed under AFM and SEM: crack bridging due to protein ligament and hydroxyapatite fibres (micro- and nanometer scale) as well as microcracks were identified. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  6. Ultralow-Carbon Nanotube-Toughened Epoxy: The Critical Role of a Double-Layer Interface.

    Science.gov (United States)

    Liu, Jingwei; Chen, Chao; Feng, Yuezhan; Liao, Yonggui; Ye, Yunsheng; Xie, Xiaolin; Mai, Yiu-Wing

    2018-01-10

    Understanding the chemistry and structure of interfaces within epoxy resins is important for studying the mechanical properties of nanofiller-filled nanocomposites as well as for developing high-performance polymer nanocomposites. Despite the intensive efforts to construct nanofiller/matrix interfaces, few studies have demonstrated an enhanced stress-transferring efficiency while avoiding unfavorable deformation due to undesirable interface fractures. Here, we report an optimized method to prepare epoxy-based nanocomposites whose interfaces are chemically modulated by poly(glycidyl methacrylate)-block-poly(hexyl methacrylate) (PGMA-b-PHMA)-functionalized multiwalled carbon nanotubes (bc@fMWNTs) and also offer a fundamental explanation of crack growth behavior and the toughening mechanism of the resulting nanocomposites. The presence of block copolymers on the surface of the MWNT results in a promising double-layered interface, in which (1) the outer-layered PGMA segment provides good dispersion in and strong interface bonding with the epoxy matrix, which enhances load transfer efficiency and debonding stress, and (2) the interlayered rubbery PHMA segment around the MWNT provides the maximum removable space for nanotubes as well as triggering cavitation while promoting local plastic matrix deformation, for example, shear banding to dissipate fracture energy. An outstanding toughening effect is achieved with only a 0.05 wt % carbon nanotube loading with the bc@fMWNT, that is, needing only a 20-times lower loading to obtain improvements in fracture toughness comparable to epoxy-based nanocomposites. The enhancements of their corresponding ultimate mode-I fracture toughnesses and fracture energies are 4 times higher than those of pristine MWNT-filled epoxy. These results demonstrate that a MWNT/epoxy interface could be optimized by changing the component structure of grafted modifiers, thereby facilitating the transfer of both mechanical load and energy dissipation

  7. Carbon black reinforced C8 ether linked bismaleimide toughened electrically conducting epoxy nanocomposites

    International Nuclear Information System (INIS)

    Mandhakini, M.; Chandramohan, A.; Jayanthi, K.; Alagar, M.

    2014-01-01

    Highlight: • The toughness of the epoxy is improved with C8e-BMI. • Conduction through ohmic contact chain takes the leading mechanism for electrical conduction instead of tunneling with 5 wt% CB. • The phase segregation between epoxy/C8 e-BMI improves the toughness of the nanocomposite. • Both toughening and flexibilization effect is responsible for improvement in impact strength. • The largest challenge of appropriate balance between the electrical conductivity and mechanical behavior is attained in a cost effective manner. - Abstract: The present work deals with the toughening of brittle epoxy matrix with C8 ether linked bismaleimide (C8 e-BMI) and then study the reinforcing effect of carbon black (CB) in enhancing the conducting properties of insulating epoxy matrix. The Fourier transform infrared spectroscopy (FTIR) and Raman analysis indicate the formation of strong covalent bonds between CB and C8 e-BMI/epoxy matrix. The X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis indicate the event of phase separation in 5 wt% CB loaded epoxy C8 e-BMI nanocomposites. The impact strength increased up to 5 wt% of CB loading with particle pull and crack deflection to be driving mechanism for enhancing the toughness of the nanocomposite and beyond 5 wt% the impact strength started to decrease due to aggregation of CB. The dynamic mechanical analysis (DMA) also indicates the toughness of the nanocomposites was improved with 5 wt% of CB loading due to the phase segregation between epoxy and C8 e-BMI in the presence of CB. The electrical conductivity was also increased with 5 wt% of CB due to classical conduction by ohmic chain contact

  8. Study of the ionizing radiation effect on the polyamide 6,6 mechanical properties

    International Nuclear Information System (INIS)

    Colombo, Maria Aparecida da Silva

    2004-01-01

    Polyamide 6,6 due to its excellent mechanical, thermal and electrical properties and its great performance in multiple industrial applications is considered one of the most important engineering polymers. However, in specific applications, some of its properties need to be improved by means additives or fillers to reach the required properties increasing its final cost. By these considerations, the aim of this work was to apply the ionizing radiation to improve the natural mechanical properties of polyamide 6,6. Also, to evaluate the irradiation parameters, and the mechanical performance of the irradiated polymer in order to use the cross-linking, induced by ionizing radiation, as substitute of additives and fillers. Row polyamide 6,6 samples, for mechanical tests, were prepared by injection molded and then irradiated with high energetic electrons to reach doses of 70, 100, 150, and 200 kGy. The mechanical performance, of non-irradiated and irradiated samples, was evaluated by tensile strength, impact, hardness and wear measurements. Furthermore, hardness and wear tests were carried out with samples, which were immersed in petroleum and sea water for 6 months. The experimental results have shown that, in the studied dose range, the tensile strength increases 25%, the hardness Shore D 15%, the impact values diminished by 80% and the wear values decreased 20 times between 0 and 200 kGy. The effect of the petroleum and sea water were shown mainly in the nonirradiated samples. (author)

  9. Proton Conductive Channel Optimization in Methanol Resistive Hybrid Hyperbranched Polyamide Proton Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Liying Ma

    2017-12-01

    Full Text Available Based on a previously developed polyamide proton conductive macromolecule, the nano-scale structure of the self-assembled proton conductive channels (PCCs is adjusted via enlarging the nano-scale pore size within the macromolecules. Hyperbranched polyamide macromolecules with different size are synthesized from different monomers to tune the nano-scale pore size within the macromolecules, and a series of hybrid membranes are prepared from these two micromoles to optimize the PCC structure in the proton exchange membrane. The optimized membrane exhibits methanol permeability low to 2.2 × 10−7 cm2/s, while the proton conductivity of the hybrid membrane can reach 0.25 S/cm at 80 °C, which was much higher than the value of the Nafion 117 membrane (0.192 S/cm. By considering the mechanical, dimensional, and the thermal properties, the hybrid hyperbranched polyamide proton exchange membrane (PEM exhibits promising application potential in direct methanol fuel cells (DMFC.

  10. Immobilization of nanoparticle titanium dioxide membrane on polyamide fabric by low temperature hydrothermal method

    International Nuclear Information System (INIS)

    Zhang Hui; Yang Lu

    2012-01-01

    A thin layer of nanoparticle titanium dioxide was immobilized on polyamide 6 (PA6) fiber using titanium sulfate and urea at low temperature hydrothermal condition. The titanium dioxide loaded fabric was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermal gravimetry techniques. The optical and mechanical properties, water absorption and degradation of methylene blue dye under ultraviolet (UV) irradiation of the PA6 fabric before and after treatments were also examined. It was found that when PA6 fabric was treated in titanium sulfate and urea aqueous solution, anatase nanocrystalline titanium dioxide was synthesized and simultaneously adhered onto the fiber surface. The average crystal size of titanium dioxide nanoparticles was about 13.2 nm. The thermal behavior of PA6 fiber distinctly changed and the onset decomposition temperature decreased. As compared with the untreated fabric, the protection against UV radiation was improved. The water absorbency increased slightly. As the fabric dimensions were reduced in warp and weft directions, the breaking load and tensile strain increased to some extent. The titanium dioxide coated fabric could degradate methylene blue dye under UV irradiation. - Highlights: ► We employed a method to immobilize TiO 2 nanoparticle on polyamide fiber. ► We fabricated the TiO 2 -coated polyamide fabric with the photocatalytic activity. ► The modification method may be suitable for the potential applications.

  11. Allosteric analysis of glucocorticoid receptor-DNA interface induced by cyclic Py-Im polyamide: a molecular dynamics simulation study.

    Directory of Open Access Journals (Sweden)

    Yaru Wang

    Full Text Available BACKGROUND: It has been extensively developed in recent years that cell-permeable small molecules, such as polyamide, can be programmed to disrupt transcription factor-DNA interfaces and can silence aberrant gene expression. For example, cyclic pyrrole-imidazole polyamide that competes with glucocorticoid receptor (GR for binding to glucocorticoid response elements could be expected to affect the DNA dependent binding by interfering with the protein-DNA interface. However, how such small molecules affect the transcription factor-DNA interfaces and gene regulatory pathways through DNA structure distortion is not fully understood so far. METHODOLOGY/PRINCIPAL FINDINGS: In the present work, we have constructed some models, especially the ternary model of polyamides+DNA+GR DNA-binding domain (GRDBD dimer, and carried out molecular dynamics simulations and free energy calculations for them to address how polyamide molecules disrupt the GRDBD and DNA interface when polyamide and protein bind at the same sites on opposite grooves of DNA. CONCLUSIONS/SIGNIFICANCE: We found that the cyclic polyamide binding in minor groove of DNA can induce a large structural perturbation of DNA, i.e. a >4 Å widening of the DNA minor groove and a compression of the major groove by more than 4 Å as compared with the DNA molecule in the GRDBD dimer+DNA complex. Further investigations for the ternary system of polyamides+DNA+GRDBD dimer and the binary system of allosteric DNA+GRDBD dimer revealed that the compression of DNA major groove surface causes GRDBD to move away from the DNA major groove with the initial average distance of ∼4 Å to the final average distance of ∼10 Å during 40 ns simulation course. Therefore, this study straightforward explores how small molecule targeting specific sites in the DNA minor groove disrupts the transcription factor-DNA interface in DNA major groove, and consequently modulates gene expression.

  12. Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mukul M. (Univeristy of Texas at Austin, Austin, TX); Freeman, Benny D. (Univeristy of Texas at Austin, Austin, TX); Van Wagner, Elizabeth M. (Univeristy of Texas at Austin, Austin, TX); Hickner, Michael A. (Pennsylvania State University, University Park, PA); Altman, Susan Jeanne

    2010-08-01

    The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterization of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved

  13. Computational model of spalling and effective fibers on toughening in fiber reinforced composites at an early stage of crack formation

    Directory of Open Access Journals (Sweden)

    Chong Wang

    Full Text Available This work suggests a computational model that takes account of effective fibers on toughening in FRC at an early stage of crack formation. We derived the distribution of pressure provoked by a random inclined fiber in the matrix and calculated stresses through integrating the pressure and tangent stress along the fiber/matrix interface with the Kelvin's fundamental solution and the Mindlin's complementary solution. The evolution of spalling in the matrix was traced. The percentages of effective fibers were evaluated with variations in strength, interface resistance, diameter and elasticity modulus. The main conclusion is that low elasticity modulus combined high strength of fibers raises dramatically the effective fibers, which would benefit toughening.

  14. Morphological Study on Room-Temperature-Cured PMMA-Grafted Natural Rubber-Toughened Epoxy/Layered Silicate Nanocomposite

    OpenAIRE

    Yuhana, N. Y.; Ahmad, S.; Kamal, M. R.; Jana, S. C.; Bahri, A. R. Shamsul

    2012-01-01

    A morphological study was conducted on ternary systems containing epoxy, PMMA-grafted natural rubber, and organic chemically modified montmorillonite (Cloisite 30B). Optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and wide-angle X-ray diffraction (WAXD) analysis were used. The following four materials were prepared at room temperature: cured unmodified epoxy, cured toughened epoxy, cured unmodified epoxy/Cloisite 3...

  15. Carboxyl-terminated butadiene-acrylonitrile-toughened epoxy/carboxyl-modified carbon nanotube nanocomposites: Thermal and mechanical properties

    Directory of Open Access Journals (Sweden)

    H. F. Xie

    2012-09-01

    Full Text Available Carboxyl-modified multi-walled carbon nanotubes (MWCNT–COOHs as nanofillers were incorporated into diglycidyl ether of bisphenol A (DGEBA toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN. The carboxyl functional carbon nanotubes were characterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. Furthermore, cure kinetics, glass transition temperature (Tg, mechanical properties, thermal stability and morphology of DGEBA/CTBN/MWCNT–COOHs nanocomposites were investigated by differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, universal test machine, thermogravimetric analysis and scanning electron microscopy (SEM. DSC kinetic studies showed that the addition of MWCNT–COOHs accelerated the curing reaction of the rubber-toughened epoxy resin. DMA results revealed that Tg of rubber-toughened epoxy nanocomposites lowered with MWCNT–COOH contents. The tensile strength, elongation at break, flexural strength and flexural modulus of DGEBA/CTBN/MWCNT-COOHs nanocomposites were increased at lower MWCNT-COOH concentration. A homogenous dispersion of nanocomposites at lower MWCNT–COOH concentration was observed by SEM.

  16. The effect of gamma irradiation in air and inert atmosphere on structure and properties of unfilled or glass fibre-reinforced polyamide 6

    Czech Academy of Sciences Publication Activity Database

    Porubská, M.; Babić, D.; Janigová, I.; Šlouf, Miroslav; Jomová, K.; Chodák, I.

    2016-01-01

    Roč. 73, č. 6 (2016), s. 1775-1794 ISSN 0170-0839 Institutional support: RVO:61389013 Keywords : polyamide 6 * glass fibre-reinforced polyamide 6 * gamma beam irradiation Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.430, year: 2016

  17. Laser surface treatment of polyamide and NiTi alloy and the effects on mesenchymal stem cell response

    Science.gov (United States)

    Waugh, D. G.; Lawrence, J.; Shukla, P.; Chan, C.; Hussain, I.; Man, H. C.; Smith, G. C.

    2015-07-01

    Mesenchymal stem cells (MSCs) are known to play important roles in development, post-natal growth, repair, and regeneration of mesenchymal tissues. What is more, surface treatments are widely reported to affect the biomimetic nature of materials. This paper will detail, discuss and compare laser surface treatment of polyamide (Polyamide 6,6), using a 60 W CO2 laser, and NiTi alloy, using a 100 W fiber laser, and the effects of these treatments on mesenchymal stem cell response. The surface morphology and composition of the polyamide and NiTi alloy were studied by scanning electron microscopy (SEM) and X-ray photoemission spectroscopy (XPS), respectively. MSC cell morphology cell counting and viability measurements were done by employing a haemocytometer and MTT colorimetric assay. The success of enhanced adhesion and spreading of the MSCs on each of the laser surface treated samples, when compared to as-received samples, is evidenced in this work.

  18. A comparison of transmission, reflection and photoacoustic FTIR techniques in the analysis of recycled and irradiated polyamide-6

    International Nuclear Information System (INIS)

    Evora, Maria C.; Goncalez, Odair L.

    2002-01-01

    A comparative study involving transmission, reflection and photoacoustic FTIR techniques is presented with analysis of polyamide-6. The potential and limitations of these methods are investigated by analyzing structural variations that take place at the surface in the bulk in recycled and irradiated polyamide-6 with a 1.5 MeV electron beam with a 500kGY dose, in the presence of O 2 . FTIR techniques appear to be sensitive in detecting small structural changes that occur in recycled and irradiated polyamide-6. The analysis of samples indicated the formation of OH, HOC=O-, - C=O groups. Also, small structural changes were detected which are characterisitic of NH and CN-C=O groups. Transmission techniques show better the structural changes in the bulk, and microscopy-FTIR appears to be more sensitive in detecting what occurs at the sample surface. (author)

  19. Environmental effect on the mechanical properties of commingled-yarn-based carbon fibre/polyamide 6 composites

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Toftegaard, Helmuth Langmaack

    2014-01-01

    The main objective of this experimental investigation was to evaluate the changes from accelerated ageing on selected properties of carbon fibre/polyamide 6 composites based on hybrid yarns. In this study, two types of mechanical tests were performed to measure the environmental influence...... on the material properties. They are three-point bending to measure the flexural strength and stiffness, and short beam three-point bending to measure the interlaminar shear strength. The 10-mm-thick quasi-isotropic carbon fibre/polyamide 6 composites with 52% volume fraction of carbon fibre to be tested were...... temperature. The interlaminar shear strength values also drop to about 75% at both −45 and 115. Extreme temperatures and long-time exposure to humidity of quasi-isotropic carbon fibre/polyamide 6 laminates can thus reduce the bending stiffness and strength by up to 35% and the interlaminar shear strength...

  20. Polyamide 6/nickel ferrite composites: morphological and structural evaluation; Compositos poliamida 6 /ferrita de niquel: avaliacao morfologica e estrutural

    Energy Technology Data Exchange (ETDEWEB)

    Menezes, P.C.F.; Santos, P.T.A.; Wanderley, A.S.D.; Costa, A.C.F.M.; Araujo, E.M., E-mail: patricia.fernandes24@hotmail.com [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Unidade Academica de Engenharia de Materiais

    2011-07-01

    This study aims to evaluate the influence of particle size of the load on the structure and morphology of polyamide composite 6/ferrita nickel. To obtain the composite, the polyamide 6 was previously vacuum dried at 80 ° C/48h to eliminate moisture, and then the load was incorporated as powders and as synthesized after calcination at 900°C in the mass concentration of 50%. Subsequently, the mixture was compressed using three tons to obtain the composites, which were characterized by XRD and SEM. XRD results showed the characteristic peaks of polyamide 6 and ferrite. An increase in crystallinity was observed for the composite loaded calcined at 900° C. SEM results showed a good dispersion of nickel ferrite loading in the matrix, the presence of larger clusters and evenly distributed load for the composite calcined at 900 ° C. (author)

  1. Evaluation of Shear Resisting Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

    International Nuclear Information System (INIS)

    Choun, Youngsun; Park, Junhee

    2014-01-01

    Conventional reinforced concrete (RC) members generally show a rapid deterioration in shear resisting mechanisms under a reversed cyclic load. However, the use of high-performance fiber-reinforced cement composites provides excellent damage tolerance under large displacement reversals compared with regular concrete. Previous experimental studies have indicated that the use of fibers in conventional RC can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. This study evaluates the shear resisting capacity for a PCCB constructed using steel fiber reinforced concrete (SFRC) or polyamide fiber reinforced concrete (PFRC). The effects of steel and polyamide fibers on the shear performance of a PCCB were investigated. It was revealed that steel fibers are more effective to enhance the shear resisting capacity of a PCCB than polyamide fibers. The ductility and energy dissipation increase significantly in fiber reinforced PCCBs

  2. Evaluation of Shear Resisting Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Choun, Youngsun; Park, Junhee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Conventional reinforced concrete (RC) members generally show a rapid deterioration in shear resisting mechanisms under a reversed cyclic load. However, the use of high-performance fiber-reinforced cement composites provides excellent damage tolerance under large displacement reversals compared with regular concrete. Previous experimental studies have indicated that the use of fibers in conventional RC can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. This study evaluates the shear resisting capacity for a PCCB constructed using steel fiber reinforced concrete (SFRC) or polyamide fiber reinforced concrete (PFRC). The effects of steel and polyamide fibers on the shear performance of a PCCB were investigated. It was revealed that steel fibers are more effective to enhance the shear resisting capacity of a PCCB than polyamide fibers. The ductility and energy dissipation increase significantly in fiber reinforced PCCBs.

  3. Synthesis and characterization of new polyamides derived from alanine and valine derivatives

    Directory of Open Access Journals (Sweden)

    El-Faham Ayman

    2012-11-01

    Full Text Available Abstract Background Many efforts have been recently devoted to design, investigate and synthesize biocompatible, biodegradable polymers for applications in medicine for either the fabrication of biodegradable devices or as drug delivery systems. Many of them consist of condensation of polymers having incorporated peptide linkages susceptible to enzymatic cleavage. Polyamides (PAs containing α-amino acid residues such as L-leucine, L-alanine and L-phenylalanine have been reported as biodegradable materials. Furthermore, polyamides (PAs derived from C10 and C14 dicarboxylic acids and amide-diamines derived from 1,6-hexanediamine or 1,12-dodecanediamine and L-phenylalanine, L-valyl-L-phenylalanine or L-phenylalanyl-L-valine residues have been reported as biocompatible polymers. We have previously described the synthesis and thermal properties of a new type of polyamides-containing amino acids based on eight new symmetric meta-oriented protected diamines derived from coupling of amino acids namely; Fomc-glycine, Fmoc-alanine, Fomc-valine and Fomc-leucine with m-phenylene diamine or 2,6-diaminopyridine. Results revealed that incorporation of pyridine onto the polymeric backbone of all series decreases the thermal stability. Here we describe another family of polyamides based on benzene dicarboxylic acid, pyridine dicarboxylic acid, and α-amino acid linked to benzidine and 4,4′-oxydianiline to study the effect of the dicarboxylic acid as well as the amino acids on the nature and thermal stability of the polymers. Results We report here the preparation of a new type of polyamides based on benzene dicarboxylic acid, pyridine dicarboxylic acid, and α-amino acid linked to benzidine and 4,4′-oxydianiline to study the effect of the dicarboxylic acid as well as the amino acids on the nature and thermal stability of polymers. The thermal properties of the polymers were evaluated by different techniques. Results revealed that structure-thermal property

  4. Sequence-selective single-molecule alkylation with a pyrrole-imidazole polyamide visualized in a DNA nanoscaffold.

    Science.gov (United States)

    Yoshidome, Tomofumi; Endo, Masayuki; Kashiwazaki, Gengo; Hidaka, Kumi; Bando, Toshikazu; Sugiyama, Hiroshi

    2012-03-14

    We demonstrate a novel strategy for visualizing sequence-selective alkylation of target double-stranded DNA (dsDNA) using a synthetic pyrrole-imidazole (PI) polyamide in a designed DNA origami scaffold. Doubly functionalized PI polyamide was designed by introduction of an alkylating agent 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI) and biotin for sequence-selective alkylation at the target sequence and subsequent streptavidin labeling, respectively. Selective alkylation of the target site in the substrate DNA was observed by analysis using sequencing gel electrophoresis. For the single-molecule observation of the alkylation by functionalized PI polyamide using atomic force microscopy (AFM), the target position in the dsDNA (∼200 base pairs) was alkylated and then visualized by labeling with streptavidin. Newly designed DNA origami scaffold named "five-well DNA frame" carrying five different dsDNA sequences in its cavities was used for the detailed analysis of the sequence-selectivity and alkylation. The 64-mer dsDNAs were introduced to five individual wells, in which target sequence AGTXCCA/TGGYACT (XY = AT, TA, GC, CG) was employed as fully matched (X = G) and one-base mismatched (X = A, T, C) sequences. The fully matched sequence was alkylated with 88% selectivity over other mismatched sequences. In addition, the PI polyamide failed to attach to the target sequence lacking the alkylation site after washing and streptavidin treatment. Therefore, the PI polyamide discriminated the one mismatched nucleotide at the single-molecule level, and alkylation anchored the PI polyamide to the target dsDNA.

  5. Effect of Polyamide 6 on Crystalline Structure of Polymer in PVDF-Nanoclay Nanocomposite

    Directory of Open Access Journals (Sweden)

    Ali Akbar Yousefi

    2012-12-01

    Full Text Available The  effect  of  nanocaly  on  crystalline  structure  of  poly(vinylidene  fuoride, PVDF, and the morphology of the resulting nano-composite were investigated using  different  characterization  techniques.  The  presence  of  3wt%  Cloisite 30B in PVDF matrix results in 11 fold increase in the percentage of beta crystalline content of the polymer. This was found to be attributed to the epitaxial effect of the clay  surface. The  beta  crystalline  content  of  the  pure  polymer  (6% was  raised  to 68% in the composite. Addition of 5wt% polyamide 6 (PA6 improved dispersion of nanoclay which led to augmentation of the viscosity and displacement of the crossover frequency of the compatibilized composite towards lower frequencies. However, due to stronger affnity of the PA6 towards organically modifed clay the epitaxial effect of  the  clay on  crystalline  structure of PVDF was  totally  eliminated. The  reduction of  viscosity  in  incompatibilized  nanocomposite was  attributed  to  reduced  number of PVDF chain entanglements  in  the presence of nanoclay. Meanwhile,  increase  in viscosity and displacement of crossover  frequency  towards  lower  frequencies were attributed to formation of clay-PA nanoparticles and PVDF-polyamide 6 interactions. It is expected that the presence of polyamide 6 promotes the formation of oriented-beta crystals in PVDF, which in turn improves the piezoelectric properties of the polymer.

  6. SYNTHESIS AND CHARACTERIZATION OF NEW THERMALLY STABLE POLYAMIDES BASED ON 2,5-PYRIDINE DICARBOXYLIC ACID AND AROMATIC DIAMINES

    OpenAIRE

    FAGHIHI, KHALIL

    2009-01-01

    Six new thermally stable polyamides 3a-f were synthesized through the polycondensation reaction of 2,5-pyridine dicarboxylic acid 1 with six different derivatives of aromatic diamines 2a-f in amedium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. The polycondensation reaction produced a series of novel polyamides containing pyridyl moieties in the main chain in high yield with inherent viscosities between 0.50-0.82 dL/g. The resulting polymers were f...

  7. Synthesis and Properties of New Polyamides Based on 4-Phenylenediacrylic Acid and Hydantoin Derivatives in the Main Chain

    OpenAIRE

    FAGHIHI, Khalil

    2008-01-01

    Six new polyamides (5a-f) containing p-phenylenediacrylic and hydantoin moieties in the main chain were prepared by direct polycondensation reaction of 4-phenylenediacrylic acid (3) with 6 different hydantoin derivatives (4a-f) using thionyl chloride and pyridine as condensing agents and N-methyl-2-pyrolidone as solvent. These new polymers (5a-f) were obtained in high yield and inherent viscosity between 0.35-0.55 dL/g. The resulting polyamides were characterized by elemental analysi...

  8. Evaluation of ionizing radiation effects on recycled polyamide-6 by infrared spectroscopy and measures of fluidity index

    International Nuclear Information System (INIS)

    Evora, Maria Cecilia; Goncalez, Odair Lelis

    2000-01-01

    In this work are presented partial results from a set of experiments and analyses performed at CTA and IPEN laboratories for the characterization of the polyamide-6, recycled and irradiated with a 1.5 MeV electron beam with a 500 kGy dose. The experimental determinations were carried out using infrared spectroscopy with Fourier transform (FTIR), in the medium infrared region (MIR) and in the far infrared region (FAR), to evaluate if exist significant changes in the infrared absorption region of the amide groups due to the polyamide irradiation. Characteristics relative to the measured fluidity index were used to evaluate the irradiated material crosslinking. (author)

  9. Effect of Graphene Nanoplatelets (GNPs on Tribological and Mechanical Behaviors of Polyamide 6 (PA6

    Directory of Open Access Journals (Sweden)

    F. Mindivan

    2017-09-01

    Full Text Available The effects of Graphene Nanoplatelet (GNP on mechanical and tribological properties of Polyamide 6 (PA6 were studied. The composites were blended using twin-screw extruder and subsequently injection molded for test samples. Mechanical properties were investigated in terms of microhardness, scratch hardness and Young’s modulus measurements and tensile test. The tribological behavior of composites was studied by using ball-on-disc reciprocating tribometer. Recent studies showed that the addition of GNP in PA6 matrix resulted in enhancement of mechanical and tribological properties.

  10. Irradiation effects on properties of reverse osmosis membrane based on cross-linked aromatic polyamide

    International Nuclear Information System (INIS)

    Nakase, Yoshiaki; Yanagi, Tadashi; Uemura, Tadahiro.

    1994-01-01

    In order to develop a membrane suitable for reverse osmotic condensation of radioactive liquid wastes, a new cross-linked aromatic polyamide composite reverse osmosis membrane (ROM) was irradiated in water or in wet system, and its mechanical and some thermal properties, and the separation performance for inorganic salt were investigated. A membrane was degraded by irradiation more severely in wet system than in dry system, probably due to the reaction with OH-radicals. In the separation performance for NaCl, the salt rejection of the membrane was kept over 88% until irradiation reached 2MGy, maintaining about 90% of its original water flux. (author)

  11. Thermal stability and degradation behavior of novel wholly aromatic azo polyamide-hydrazides

    International Nuclear Information System (INIS)

    Al-Ghamdia, R.F.; Fahmib, M.M.; Mohamed, N.A.

    2005-01-01

    Thermal stability and degradation behavior of a series of novel wholly aromatic azo polyamide-hydrazides have been investigated in nitrogen and in air atmospheres using differential scanning ealorimetry, thermogravimetry, infrared spectroscopy and elemental analysis. The influences of controlled structural variations and molecular weight on the thermal stability and degradation behavior of this series of polymers have also been studied. The structural differences were achieved by varying the content of para- and meta substituted phenylene rings incorporated within this series. The polymers were prepared by a low temperature solution polycondensation reaction of p aminosalicylic acid hydrazide and an equimolar amount of 4,4-azo dibenzoyl chloride [4,4 ADBC] or 3,3-azo dibenzoyl chloride [3,3ADBC] or mixtures of various molar ratios of 4,4ADBC and 3,3ADBC in anhydrous N,N- dimethyl acetamide [DMAc] containing lithium chloride as a solvent at -10 degree C. The results clearly reveal that these polymers are characterized by high thermal stability. Their weight loss occurred in three distinctive steps. The first was small and assigned to the evaporation of absorbed moisture. The second was appreciable and was attributed to the cyclo dehydration reaction of the hydrazide groups into 1,3,4-oxadiazole rings by losing water, combined with elimination of azo groups by losing molecular nitrogen. This is not a true degradation but rather a thermo-chemical transformation reaction of the azo polyamide-hydrasdes into the corresponding polyamide-l,3,4-oxadiazoles. The third was relatively severe and sharp, particularly in air, and corresponded to the decomposition of the resulting polyamide-l, 3,4-oxadiazoles. In both degradation atmospheres, the improved resistance to high temperatures was always associated with increased content of para- phenylene moieties of the investigated polymer. Further, with exception of 160-200 degree C temperature range, where the lower molecular weight

  12. Mechanical thermal evaluation of polyamide 6 with bentonite organo clay nanocomposites

    International Nuclear Information System (INIS)

    Paz, Rene Anisio da; Araujo, Edcleide M.; Melo, Tomas Jeferson Alves de; Leite, Amanda M.D.; Cavalcanti, Shirley Nobrega; Pessan, Luiz Antonio

    2009-01-01

    This work had for objective to obtain polymeric nanocomposites of polyamide 6 and a clay consisting of silicates layer from of Paraiba mines and to evaluate evaluation mechanical thermal in different processing conditions. The clay was organically modified using a quaternary ammonium salt (Cetremide), so that there is a larger interaction of the clay with the polymer. The obtained nanocomposites showed the morphological structure composed exfoliated/partially exfoliated, as shown XRD. The results of HDT it because the clay increases the dimensional stability of PA6 in high temperatures, making possible the use of the nanocomposites for making of pieces with good resistance to the heat distortion. (author)

  13. Polyamide microcapsules containing jojoba oil prepared by inter-facial polymerization.

    Science.gov (United States)

    Persico, P; Carfagna, C; Danicher, L; Frere, Y

    2005-08-01

    Jojoba oil containing polyamide microcapsules having diameter of approximately 5 microm were prepared by inter-facial polycondensation by direct method (oil-in-water). Qualitative effects of both the formulation and the process parameters on microcapsules characteristics were investigated by SEM observations. Morphological analysis showed the dependence of the external membrane compactness on the chemical nature of the water-soluble polyamine and the oil-soluble acid polychloride: 1,6-hexamethylenediamine (HMDA) and terephthaloyl dichloride (TDC) were found to favour the production of smooth and dense surfaces. The use of ultrasonic irradiations during the dispersion step to get a further reduction of microcapsules size was also evaluated.

  14. Synthesis and characterization of lead oxides for preparation of nanocomposites with polyamide

    International Nuclear Information System (INIS)

    Cado, Ronan Gorski; Severo, Vinicius A.; Bulhores, Luis Otavio S.

    2016-01-01

    Lead oxide nanoparticles with diameters between 100 to 250 nm were obtained using a polymeric precursor method in the presence of citric acid and ethylene glycol. X-ray diffraction (XRD) and dynamic light scattering to measure the size and zeta potential in solution in dispersions with different pH were used to characterize the as-obtained samples. The nanoparticles were incorporated into polyamide 6.6 and composite films were prepared by electrospinning being evaluated the variation of the mechanical properties of the polymer and its effectiveness in attenuation of X-rays. (author)

  15. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    Energy Technology Data Exchange (ETDEWEB)

    Zhul' kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L., E-mail: iordan@chph.ras.ru [Russian Academy of Sciences, Semenov Institute of Chemical Physics (Russian Federation)

    2009-05-15

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  16. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    International Nuclear Information System (INIS)

    Zhul'kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L.

    2009-01-01

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  17. Ductile-phase toughening in V-V3Si in situ composites

    International Nuclear Information System (INIS)

    Henshall, G.; Strum, M.J.; Bewlay, B.P.; Sutliff, J.A.

    1997-01-01

    This article describes the room-temperature fracture behavior of ductile-phase-toughened V-V 3 Si in situ composites that were produced by arc melting (AM), cold-crucible induction melting (IM), and cold-crucible directional solidification (DS). Composites were produced containing a wide range of microstructures, interstitial impurity contents, and volume fractions of the ductile V-Si solid solution phase, denoted (V). The fracture toughness of these composites generally increases as the volume fraction of (V) increases, but is strongly influenced by the microstructure, the mechanical properties of the component phases, and the crystallographic orientation of the (V) phase with respect to the maximum principal stress direction. For eutectic composites that have a (V) volume fraction of about 50 pct, the fracture toughness increases with decreasing ''''effective'''' interstitial impurity concentration, [I] = [N] + 1.33 [O] + 9 [H]. As [I] decreases from 1,400 ppm (AM) to 400 ppm (IM), the fracture toughness of the eutectic composites increases from 10 to 20 MPa √m. Further, the fracture toughness of the DS eutectic composites is greater when the crack propagation direction is perpendicular, rather than parallel, to the composite growth direction. These results are discussed in light of conventional ductile-phase bridging theories, which alone cannot fully explain the fracture toughness of V-Si in situ composites

  18. Fatigue Performance and Multiscale Mechanisms of Concrete Toughened by Polymers and Waste Rubber

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2014-01-01

    Full Text Available For improving bending toughness and fatigue performance of brittle cement-based composites, two types of water-soluble polymers (such as dispersible latex powder and polyvinyl alcohol powder and waste tire-rubber powders are added to concrete as admixtures. Multiscale toughening mechanisms of these additions in concretes were comprehensively investigated. Four-point bending fatigue performance of four series concretes is conducted under a stress level of 0.70. The results show that the effects of dispersible latex powder on bending toughness and fatigue life of concrete are better than those of polyvinyl alcohol powder. Furthermore, the bending fatigue lives of concrete simultaneously containing polymers and waste rubber powders are larger than those of concrete with only one type of admixtures. The multiscale physics-chemical mechanisms show that high bonding effect and high elastic modulus of polymer films as well as good elastic property and crack-resistance of waste tire-rubber powders are beneficial for improving bending toughness and fatigue life of cementitious composites.

  19. Study of toughening mechanisms through the observations of crack propagation in nanostructured and layered metallic sheet

    International Nuclear Information System (INIS)

    Chen, A.Y.; Li, D.F.; Zhang, J.B.; Liu, F.; Liu, X.R.; Lu, J.

    2011-01-01

    Highlights: → A nanostructured and layered steel exhibits high strength and large ductility. → The excellent combination originates from a multiple interlaminar cracking. → The initiation and propagation of cracks are controlled by three aspects. → The cracks are deflected by interface and arrested by compressive residual stress. → Finally, the cracks are blunted by the graded grain size distribution. - Abstract: A layered and nanostructured (LN) 304 SS sheet was produced by combination of surface mechanical attrition treatment (SMAT) with warm co-rolling. The microstructure of LN sheet is characterized by a periodic distribution of nanocrystalline layers and micron-grained layers with a graded transition of grain size. Tensile test results show that exceptional properties of high yield strength and large elongation to fracture are achieved. A multiple interlaminar cracking was observed by scanning electron microscopy, which is induced by repeated crack initiation and propagation. The toughening mechanisms of the LN sheet are proposed to be controlling the crack propagation path by several strategies. The main cracks initiating at interface defects are arrested by large compressive residual stress, deflected by weak interface bonding and blunted by the graded grain size distribution.

  20. Microstructural characterization of a zirconia-toughened alumina fiber reinforced niobium aluminide composite

    International Nuclear Information System (INIS)

    Nourbakhsh, S.; Sahin, O.; Rhee, W.H.; Margolin, H.

    1992-01-01

    This paper reports on an NbAl 3 + Nb 2 Al composite reinforced with continuous zirconia-toughened alumina, PRD-166 fibers, that was produced by pressure casing and was examined by optical and transmission electron microscopy and energy dispersive spectroscopy. Exposure of the fiber to the molten metal resulted in ZrO 2 and Al; 2 O 3 grain growth, formation of a thin layer of an amorphous phase on the grain boundaries of Al 2 O 3 and transformation of ZrO 2 . Preferential Al 2 O 3 grain growth near the surface of the fiber led to the rejection of ZrO 2 from this region into the molten metal. In NbAl 3 slip occurred by the glide of a left-angle 110 right-angle superdislocations and to a lesser extent by the glide of a pair of left-angle 11 bar 1 right-angle + left-angle 3 bar 1 bar 1 right-angle dislocations on the (112) planes and a/2 left-angle 110 right-angle superpartial dislocations on the (001) plane. The operating slip system in Nb 2 Al was identified as {010 left-angle 100 right-angle. A left-angle 100 right-angle dislocations were dissociated into a/x left-angle 100 right-angle partial dislocations joined together by a stacking fault

  1. Toughening of Thermoresponsive Arrested Networks of Elastin-Like Polypeptides To Engineer Cytocompatible Tissue Scaffolds.

    Science.gov (United States)

    Glassman, Matthew J; Avery, Reginald K; Khademhosseini, Ali; Olsen, Bradley D

    2016-02-08

    Formulation of tissue engineering or regenerative scaffolds from simple bioactive polymers with tunable structure and mechanics is crucial for the regeneration of complex tissues, and hydrogels from recombinant proteins, such as elastin-like polypeptides (ELPs), are promising platforms to support these applications. The arrested phase separation of ELPs has been shown to yield remarkably stiff, biocontinuous, nanostructured networks, but these gels are limited in applications by their relatively brittle nature. Here, a gel-forming ELP is chain-extended by telechelic oxidative coupling, forming extensible, tough hydrogels. Small angle scattering indicates that the chain-extended polypeptides form a fractal network of nanoscale aggregates over a broad concentration range, accessing moduli ranging from 5 kPa to over 1 MPa over a concentration range of 5-30 wt %. These networks exhibited excellent erosion resistance and allowed for the diffusion and release of encapsulated particles consistent with a bicontinuous, porous structure with a broad distribution of pore sizes. Biofunctionalized, toughened networks were found to maintain the viability of human mesenchymal stem cells (hMSCs) in 2D, demonstrating signs of osteogenesis even in cell media without osteogenic molecules. Furthermore, chondrocytes could be readily mixed into these gels via thermoresponsive assembly and remained viable in extended culture. These studies demonstrate the ability to engineer ELP-based arrested physical networks on the molecular level to form reinforced, cytocompatible hydrogel matrices, supporting the promise of these new materials as candidates for the engineering and regeneration of stiff tissues.

  2. Zirconia toughened alumina ceramic foams for potential bone graft applications: fabrication, bioactivation, and cellular responses.

    Science.gov (United States)

    He, X; Zhang, Y Z; Mansell, J P; Su, B

    2008-07-01

    Zirconia toughened alumina (ZTA) has been regarded as the next generation orthopedic graft material due to its excellent mechanical properties and biocompatibility. Porous ZTA ceramics with good interconnectivity can potentially be used as bone grafts for load-bearing applications. In this work, three-dimensional (3D) interconnected porous ZTA ceramics were fabricated using a direct foaming method with egg white protein as binder and foaming agent. The results showed that the porous ZTA ceramics possessed a bimodal pore size distribution. Their mechanical properties were comparable to those of cancellous bone. Due to the bio-inertness of alumina and zirconia ceramics, surface bioactivation of the ZTA foams was carried out in order to improve their bioactivity. A simple NaOH soaking method was employed to change the surface chemistry of ZTA through hydroxylation. Treated samples were tested by conducting osteoblast-like cell culture in vitro. Improvement on cells response was observed and the strength of porous ZTA has not been deteriorated after the NaOH treatment. The porous 'bioactivated' ZTA ceramics produced here could be potentially used as non-degradable bone grafts for load-bearing applications.

  3. Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

    Science.gov (United States)

    Smith, Robert A.; Nelson, Luke J.; Mienczakowski, Martin J.

    2018-04-01

    Ultrasonic 3D characterization of ply-level features in layered composites, such as out-of-plane wrinkles and ply drops, is now possible with carefully applied analytic-signal analysis. Study of instantaneous amplitude, phase and frequency in the ultrasonic response has revealed some interesting effects, which become more problematic for 3D characterization as the inter-ply resin-layer thicknesses increase. In modern particle-toughened laminates, the thicker resin layers cause phase singularities to be observed; these are locations where the instantaneous amplitude is zero, so the instantaneous phase is undefined. The depth at which these occur has been observed experimentally to vary with resin- layer thickness, such that a phase-singularity surface is formed; beyond this surface, the ultrasonic response is reduced and significantly more difficult to interpret, so a method for removing the effect would be advantageous. The underlying physics has been studied using an analytical one-dimensional multi-layer model. This has been sufficient to determine that the cause is linked to a phononic band gap in the ultrasound transmitted through multiple equally-spaced partial reflectors. As a result, the phase singularity also depends on input-pulse center frequency and bandwidth. Various methods for overcoming the confusing effects in the data have been proposed and subsequently investigated using the analytical model. This paper will show experimental and modelled evidence of phase-singularities and phase-singularity surfaces, as well as the success of methods for reducing their effects.

  4. Toughened and machinable glass matrix composites reinforced with graphene and graphene-oxide nano platelets

    Science.gov (United States)

    Porwal, Harshit; Tatarko, Peter; Grasso, Salvatore; Hu, Chunfeng; Boccaccini, Aldo R; Dlouhý, Ivo; Reece, Mike J

    2013-01-01

    The processing conditions for preparing well dispersed silica–graphene nanoplatelets and silica–graphene oxide nanoplatelets (GONP) composites were optimized using powder and colloidal processing routes. Fully dense silica–GONP composites with up to 2.5 vol% loading were consolidated using spark plasma sintering. The GONP aligned perpendicularly to the applied pressure during sintering. The fracture toughness of the composites increased linearly with increasing concentration of GONP and reached a value of ∼0.9 MPa m1/2 for 2.5 vol% loading. Various toughening mechanisms including GONP necking, GONP pull-out, crack bridging, crack deflection and crack branching were observed. GONP decreased the hardness and brittleness index (BI) of the composites by ∼30 and ∼50% respectively. The decrease in BI makes silica–GONP composites machinable compared to pure silica. When compared to silica–Carbon nanotube composites, silica–GONP composites show better process-ability and enhanced mechanical properties. PMID:27877614

  5. Toughening and healing of composites by CNTs reinforced copolymer nylon micro-particles

    Science.gov (United States)

    Kostopoulos, V.; Kotrotsos, A.; Tsokanas, P.; Tsantzalis, S.

    2018-02-01

    In this work, nylon micro-particles, both undoped and doped with multiwall carbon nanotubes played the role of the self-healing agent into carbon fibre/epoxy composites (CFRPs). These micro-particles were blended with epoxy matrix and the resulting mixture was used for the composites fabrication. Three types of composites were manufactured; the reference CFRP and the modified CFRPs with undoped and doped nylon micro-particles. After manufacturing, these composites were tested under mode I and II fracture loading conditions and it was shown that the interlaminar fracture toughness characteristics of both nylon modified composites were significantly increased. After first fracture, healing process was activated for the tested nylon modified samples and revealed high fracture toughness characteristics recovery. Morphology examinations supported the results and elucidated the involved toughening and failure mechanisms. Finally, the in-plane mechanical and thermo-mechanical properties of all the composites were characterized for identifying possible knock-down effects due to the nylon modification of composites.

  6. Nanocellulose composites with enhanced interfacial compatibility and mechanical properties using a hybrid-toughened epoxy matrix.

    Science.gov (United States)

    Kuo, Pei-Yu; Barros, Luizmar de Assis; Yan, Ning; Sain, Mohini; Qing, Yan; Wu, Yiqiang

    2017-12-01

    Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites for achieving a higher sustainability, mechanical performance of these composites is limited due to the poor compatibility between fibre reinforcement and polymer matrices. Here we developed a bio-nanocomposite with an enhanced fibre/resin interface using a hybrid-toughened epoxy. A strong reinforcing effect of NCFs was achieved, demonstrating an increase up to 88% in tensile strength and 298% in tensile modulus as compared to neat petro-based P-epoxy. The toughness of neat P-epoxy was improved by 84% with the addition of 10wt% bio-based E-epoxy monomers, which also mitigated the amount of usage of bisphenol A (BPA). The morphological analyses showed that the hybrid epoxy improved the resin penetration and fibre distribution significantly in the resulting composites. Thus, our findings demonstrated the promise of developing sustainable and high performance epoxy composites combing NCFs with a hybrid petro-based and bio-based epoxy resin system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Fabrication of Electrospun Polyamide-6/Chitosan Nanofibrous Membrane toward Anionic Dyes Removal

    Directory of Open Access Journals (Sweden)

    Mozhdeh Ghani

    2014-01-01

    Full Text Available Nanofibrous filter media of polyamide-6/chitosan were fabricated by electrospinning onto a satin fabric substrate and characterized by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, and water contact angle (WCA. Anionic dye removal capability of the filter was investigated for Solophenyl Red 3BL and Polar Yellow GN, respectively, as acidic and direct dyes were investigated with respect to solution parameters (pH and initial dye concentration and membrane parameters (electrospinning time and chitosan ratio through filtration system. Experiments were designed using response surface methodology (RSM based on five-level central composite design (CCD with four parameters to maximize removal efficiency of the filter media. Moreover, the effect of parameters and their likely interactions on dye removal were investigated by mathematically developed models. The optimum values for solution pH, initial dye concentration, electrospinning time, and chitosan ratio were predicted to be 5, 50 mg/L, 4 hr, 30% and 5, 100 mg/L, 4 hr, 10%, respectively, for achieving 96% and 95% removal of Solophenyl Red 3BL and Polar Yellow GN. Evaluation of the estimation capability of applied models revealed that the models have a good agreement with experimental values. This study demonstrated that polyamide-6/chitosan nanofibrous membrane has an enormous applicable potential in dye removal from aqueous solutions.

  8. Modelling mechanical properties of the multilayer composite materials with the polyamide core

    Directory of Open Access Journals (Sweden)

    Talaśka Krzysztof

    2018-01-01

    Full Text Available Due to the wide range of application for belt conveyors, engineers look for many different combinations of mechanical properties of conveyor and transmission belts. It can be made by creating multilayer or fibre reinforced composite materials from base thermoplastic or thermosetting polymers. In order to gain high strength with proper elasticity and friction coefficient, the core of the composite conveyor belt is made of polyamide film core, which can be combined with various types of polymer fabrics, films or even rubbers. In this paper authors show the complex model of multilayer composite belt with the polyamide core, which can be used in simulation analyses. The following model was derived based on the experimental research, which consisted of tensile, compression and shearing tests. In order to achieve the most accurate model, proper simulations in ABAQUS were made and then the results were compared with empirical mechanical characteristics of a conveyor belt. The main goal of this research is to fully describe the perforation process of conveyor and transmission belts for vacuum belt conveyors. The following model will help to develop design briefs for machines used for mechanical perforation.

  9. Design and Characterization of Electrospun Polyamide Nanofiber Media for Air Filtration Applications

    Directory of Open Access Journals (Sweden)

    Jonas Matulevicius

    2014-01-01

    Full Text Available Electrospun polyamide 6 (PA 6 and polyamide 6/6 (PA 6/6 nanofibers were produced in order to investigate their experimental characteristics with the goal of obtaining filtration relevant fiber media. The experimental design model of each PA nanofibers contained the following variables: polymer concentration, ratio of solvents, nanofiber media collection time, tip-to-collector distance, and the deposition voltage. The average diameter of the fibers, their morphology, basis weight, thickness, and resulting media solidity were investigated. Effects of each variable on the essential characteristics of PA 6/6 and PA 6 nanofiber media were studied. The comparative analysis of the obtained PA 6/6 and PA 6 nanofiber characteristics revealed that PA 6/6 had higher potential to be used in filtration applications. Based on the experimental results, the graphical representation—response surfaces—for obtaining nanofiber media with the desirable fiber diameter and basis weight characteristics were derived. Based on the modelling results the nanofiber filter media (mats were fabricated. Filtration results revealed that nanofiber filter media electrospun from PA6/6 8% (w/vol solutions with the smallest fiber diameters (62–66 nm had the highest filtration efficiency (PA6/6_30 = 84.9–90.9% and the highest quality factor (PA6/6_10 = 0.0486–0.0749 Pa−1.

  10. An HRE-Binding Py-Im Polyamide Impairs Hypoxic Signaling in Tumors.

    Science.gov (United States)

    Szablowski, Jerzy O; Raskatov, Jevgenij A; Dervan, Peter B

    2016-04-01

    Hypoxic gene expression contributes to the pathogenesis of many diseases, including organ fibrosis, age-related macular degeneration, and cancer. Hypoxia-inducible factor-1 (HIF1), a transcription factor central to the hypoxic gene expression, mediates multiple processes including neovascularization, cancer metastasis, and cell survival. Pyrrole-imidazole polyamide 1: has been shown to inhibit HIF1-mediated gene expression in cell culture but its activity in vivo was unknown. This study reports activity of polyamide 1: in subcutaneous tumors capable of mounting a hypoxic response and showing neovascularization. We show that 1: distributes into subcutaneous tumor xenografts and normal tissues, reduces the expression of proangiogenic and prometastatic factors, inhibits the formation of new tumor blood vessels, and suppresses tumor growth. Tumors treated with 1: show no increase in HIF1α and have reduced ability to adapt to the hypoxic conditions, as evidenced by increased apoptosis in HIF1α-positive regions and the increased proximity of necrotic regions to vasculature. Overall, these results show that a molecule designed to block the transcriptional activity of HIF1 has potent antitumor activity in vivo, consistent with partial inhibition of the tumor hypoxic response. Mol Cancer Ther; 15(4); 608-17. ©2015 AACR. ©2015 American Association for Cancer Research.

  11. Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

    Science.gov (United States)

    Wang, J.; Magee, D.; Schneider, J. A.

    2009-01-01

    The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

  12. Fire resistant polyamide based on 1-(diorganooxyphosphonyl)methyl-2,4- and -2,6diamino benzene

    Science.gov (United States)

    Mikroyannidis, J. A. (Inventor); Kourtides, D. A. (Inventor)

    1986-01-01

    1-(Diorganooxyphosphonyl)methyl2,4- and-2,6diamino benzenes are reacted with polyacylhalides and optionally comonomers to produce polyamides which have desirable heat and fire resistance properties. These polymers are used to form fibers and fabrics where fire resistance properties are important, e.g., aircraft equipment and structures.

  13. Rigid, bio-based polyamides from galactaric acid derivatives with elevated glass transition temperatures and their characterization

    NARCIS (Netherlands)

    Wróblewska, Aleksandra A.; Bernaerts, Katrien; de Wildeman, Stefaan

    2017-01-01

    A comparative study was prepared investigating the synthesis of polyamides using bio-based building blocks derived from sugar beet pulp, namely 2,3:4,5-di-O-methylene-galactarate (GalXH) and 2,3:4,5-di-O-isopropylidene-galactarate (GalXMe) derivatives. Two different approaches towards the synthesis

  14. Thermo-oxidative degradation study of melt-processed polyethylene and its blend with polyamide using time-resolved rheometry

    CSIR Research Space (South Africa)

    Salehiyan, Reza

    2017-05-01

    Full Text Available Time-resolved mechanical spectroscopy (TRMS) was conducted to study the thermo-oxidative degradation of linear low density polyethylene (LLDPE) samples with different thermal histories and their blends with a polyamide (PA6) in the melt state. Neat...

  15. Correlating PSf Support Physicochemical Properties with the Formation of Piperazine-Based Polyamide and Evaluating the Resultant Nanofiltration Membrane Performance

    Directory of Open Access Journals (Sweden)

    Micah Belle Marie Yap Ang

    2017-10-01

    Full Text Available Membrane support properties influence the performance of thin-film composite nanofiltration membranes. We fabricated several polysulfone (PSf supports. The physicochemical properties of PSf were altered by adding polyethylene glycol (PEG of varying molecular weights (200–35,000 g/mol. This alteration facilitated the formation of a thin polyamide layer on the PSf surface during the interfacial polymerization reaction involving an aqueous solution of piperazine containing 4-aminobenzoic acid and an organic solution of trimesoyl chloride. Attenuated total reflectance-Fourier transform infrared validated the presence of PEG in the membrane support. Scanning electron microscopy and atomic force microscopy illustrated that the thin-film polyamide layer morphology transformed from a rough to a smooth surface. A cross-flow filtration test indicated that a thin-film composite polyamide membrane comprising a PSf support (TFC-PEG20k with a low surface porosity, small pore size, and suitable hydrophilicity delivered the highest water flux and separation efficiency (J = 81.1 ± 6.4 L·m−2·h−1, RNa2SO4 = 91.1% ± 1.8%, and RNaCl = 35.7% ± 3.1% at 0.60 MPa. This membrane had a molecular weight cutoff of 292 g/mol and also a high rejection for negatively charged dyes. Therefore, a PSf support exhibiting suitable physicochemical properties endowed a thin-film composite polyamide membrane with high performance.

  16. COMPOSITE POLYMERICADDITIVESDESIGNATED FORCONCRETEMIXES BASED ONPOLYACRYLATES, PRODUCTS OF THERMAL DECOMPOSITION OF POLYAMIDE-6 AND LOW-MOLECULAR POLYETHYLENE

    Directory of Open Access Journals (Sweden)

    Polyakov Vyacheslav Sergeevich

    2012-07-01

    4 the optimal composite additive that increases the time period of stiffening of the cement grout , improves the water resistance and the compressive strength of concrete, represents the composition of polyacrylates and polymethacrylates, products of thermal decomposition of polyamide-6 and low-molecular polyethylene in the weight ratio of 1:1:0.5.

  17. Effects of surface coating process conditions on the water permeation and salt rejection properties of composite polyamide reverse osmosis membranes

    KAUST Repository

    Louie, Jennifer Sarah; Pinnau, Ingo; Reinhard, Martin

    2011-01-01

    are impacted by the coating process steps, and investigates how such effects could contribute to lower water flux. On one hand, simply pre-soaking dry aromatic polyamide composite membranes in aliphatic alcohols results in a significant increase in water flux

  18. Tensile fracture and thermal conductivity characterization of toughened epoxy/CNT nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, Anandh [School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019 (United States); Saha, Mrinal C., E-mail: msaha@ou.edu [School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019 (United States)

    2011-01-25

    Rubber toughened epoxy/CNT nanocomposites were manufactured at different weight percents between 0 and 1% of multiwall carbon nanotube (MWNT) using a high intensity ultrasonic liquid processor with a titanium probe. Mechanical properties of manufactured dog bone samples were measured in tension and the results indicated a maximum of 23% increase in the elastic modulus at 0.6% by weight of MWNT. However, the fracture strength showed a maximum decrease of about 11% as a function of increasing MWNT loading. Scanning Electron Microscopy (SEM) images from the neat samples revealed a distinct circular pit at the top left edge of the specimen with an overall tearing deformation causing the fracture paths. Comparatively, all nanocomposite samples on an average seemed to show a prominent brittle fracture with little or no evidence of circular pit formation. The amount of tearing deformation seemed to be enhanced in the nanocomposite specimens as compare to the neat ones. Finally, Transmission Electron Microscopy images indicated that different states of dispersion exist in all of the nanocomposite samples. The data showed that agglomeration of nanotubes increases as a function of weight percent. In addition to mechanical property characterization, thermal conductivity of all the samples was determined as a function of temperature between 30 deg. C and 100 deg. C using the 3{omega} method. The tested samples showed an almost 16% increase in thermal conductivity. The minimal enhancement in thermal conductivity has been analyzed from the standpoint of the Effective Medium Theory. Interfacial thermal resistances exhibit no order of magnitude changes explaining the conductivity results.

  19. Tensile fracture and thermal conductivity characterization of toughened epoxy/CNT nanocomposites

    International Nuclear Information System (INIS)

    Balakrishnan, Anandh; Saha, Mrinal C.

    2011-01-01

    Rubber toughened epoxy/CNT nanocomposites were manufactured at different weight percents between 0 and 1% of multiwall carbon nanotube (MWNT) using a high intensity ultrasonic liquid processor with a titanium probe. Mechanical properties of manufactured dog bone samples were measured in tension and the results indicated a maximum of 23% increase in the elastic modulus at 0.6% by weight of MWNT. However, the fracture strength showed a maximum decrease of about 11% as a function of increasing MWNT loading. Scanning Electron Microscopy (SEM) images from the neat samples revealed a distinct circular pit at the top left edge of the specimen with an overall tearing deformation causing the fracture paths. Comparatively, all nanocomposite samples on an average seemed to show a prominent brittle fracture with little or no evidence of circular pit formation. The amount of tearing deformation seemed to be enhanced in the nanocomposite specimens as compare to the neat ones. Finally, Transmission Electron Microscopy images indicated that different states of dispersion exist in all of the nanocomposite samples. The data showed that agglomeration of nanotubes increases as a function of weight percent. In addition to mechanical property characterization, thermal conductivity of all the samples was determined as a function of temperature between 30 deg. C and 100 deg. C using the 3ω method. The tested samples showed an almost 16% increase in thermal conductivity. The minimal enhancement in thermal conductivity has been analyzed from the standpoint of the Effective Medium Theory. Interfacial thermal resistances exhibit no order of magnitude changes explaining the conductivity results.

  20. Highly Porous, Rigid-Rod Polyamide Aerogels with Superior Mechanical Properties and Unusually High Thermal Conductivity.

    Science.gov (United States)

    Williams, Jarrod C; Nguyen, Baochau N; McCorkle, Linda; Scheiman, Daniel; Griffin, Justin S; Steiner, Stephen A; Meador, Mary Ann B

    2017-01-18

    We report here the fabrication of polyamide aerogels composed of poly-p-phenylene-terephthalamide, the same backbone chemistry as DuPont's Kevlar. The all-para-substituted polymers gel without the use of cross-linker and maintain their shape during processing-an improvement over the meta-substituted cross-linked polyamide aerogels reported previously. Solutions containing calcium chloride (CaCl 2 ) and para-phenylenediamine (pPDA) in N-methylpyrrolidinone (NMP) at low temperature are reacted with terephthaloyl chloride (TPC). Polymerization proceeds over the course of 5 min resulting in gelation. Removal of the reaction solvent via solvent exchange followed by extraction with supercritical carbon dioxide provides aerogels with densities ranging from 0.1 to 0.3 g/cm 3 , depending on the concentration of calcium chloride, the formulated number of repeat units, n, and the concentration of polymer in the reaction mixture. These variables were assessed in a statistical experimental study to understand their effects on the properties of the aerogels. Aerogels made using at least 30 wt % CaCl 2 had the best strength when compared to aerogels of similar density. Furthermore, aerogels made using 30 wt % CaCl 2 exhibited the lowest shrinkage when aged at elevated temperatures. Notably, whereas most aerogel materials are highly insulating (thermal conductivities of 10-30 mW/m K), the polyamide aerogels produced here exhibit remarkably high thermal conductivities (50-80 mW/(m K)) at the same densities as other inorganic and polymer aerogels. These high thermal conductivities are attributed to efficient phonon transport by the rigid-rod polymer backbone. In conjunction with their low cost, ease of fabrication with respect to other polymer aerogels, low densities, and high mass-normalized strength and stiffness properties, these aerogels are uniquely valuable for applications such as lightweighting in consumer electronics, automobiles, and aerospace where weight reduction is

  1. Morphological Study on Room-Temperature-Cured PMMA-Grafted Natural Rubber-Toughened Epoxy/Layered Silicate Nanocomposite

    Directory of Open Access Journals (Sweden)

    N. Y. Yuhana

    2012-01-01

    Full Text Available A morphological study was conducted on ternary systems containing epoxy, PMMA-grafted natural rubber, and organic chemically modified montmorillonite (Cloisite 30B. Optical microscopy, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy dispersive X-ray (EDX, and wide-angle X-ray diffraction (WAXD analysis were used. The following four materials were prepared at room temperature: cured unmodified epoxy, cured toughened epoxy, cured unmodified epoxy/Cloisite 30B nanocomposites, and cured toughened epoxy/Cloisite 30B nanocomposites. Mixing process was performed by mechanical stirring. Poly(etheramine was used as the curing agent. The detailed TEM images revealed co-continuous and dispersed spherical rubber in the epoxy-rubber blend, suggesting a new proposed mechanism of phase separation. High-magnification TEM analysis showed good interactions between rubber and Cloisite 30B in the ternary system. Also, it was found that rubber particles could enhance the separation of silicates layers. Both XRD and TEM analyses confirmed that the intercalation of Cloisite 30B was achieved. No distinct exfoliated silicates were observed by TEM. Aggregates of layered silicates (tactoids were observed by SEM and EDX, in addition to TEM at low magnification. EDX analysis confirmed the presence of organic and inorganic elements in the binary and ternary epoxy systems containing Cloisite 30B.

  2. Integrated Ternary Bioinspired Nanocomposites via Synergistic Toughening of Reduced Graphene Oxide and Double-Walled Carbon Nanotubes.

    Science.gov (United States)

    Gong, Shanshan; Cui, Wei; Zhang, Qi; Cao, Anyuan; Jiang, Lei; Cheng, Qunfeng

    2015-12-22

    With its synergistic toughening effect and hierarchical micro/nanoscale structure, natural nacre sets a "gold standard" for nacre-inspired materials with integrated high strength and toughness. We demonstrated strong and tough ternary bioinspired nanocomposites through synergistic toughening of reduced graphene oxide and double-walled carbon nanotube (DWNT) and covalent bonding. The tensile strength and toughness of this kind of ternary bioinspired nanocomposites reaches 374.1 ± 22.8 MPa and 9.2 ± 0.8 MJ/m(3), which is 2.6 and 3.3 times that of pure reduced graphene oxide film, respectively. Furthermore, this ternary bioinspired nanocomposite has a high conductivity of 394.0 ± 6.8 S/cm and also shows excellent fatigue-resistant properties, which may enable this material to be used in aerospace, flexible energy devices, and artificial muscle. The synergistic building blocks with covalent bonding for constructing ternary bioinspired nanocomposites can serve as the basis of a strategy for the construction of integrated, high-performance, reduced graphene oxide (rGO)-based nanocomposites in the future.

  3. Mercuric iodide composite films using polyamide, polycarbonate and polystyrene fabricated by casting

    International Nuclear Information System (INIS)

    Ugucioni, J.C.; Ghilardi Netto, T.; Mulato, M.

    2010-01-01

    Mercuric iodide (HgI 2 ) composite films were obtained by using the casting technique. Insulator polymers such as polyamide, polycarbonate and polystyrene were mixed to HgI 2 crystallites forming a final sub-millimeter thick self-standing film. Fabrication temperature varied from 10 to 100 o C, and total fabrication time reached at most 5 min. The larger the fabrication temperature, the thinner the film and the smaller its electrical resistivity. Electrical characterization was performed in the dark, under UV illumination and under mammographic X-ray exposure. The final properties of the films are discussed and related to fabrication conditions. The optimized composite film might be a better candidate for use as X-ray detector for medical imaging, in place of the single HgI 2 crystalline device.

  4. The Development of Biomimetic Spherical Hydroxyapatite/Polyamide 66 Biocomposites as Bone Repair Materials

    Directory of Open Access Journals (Sweden)

    Xuesong Zhang

    2014-01-01

    Full Text Available A novel biomedical material composed of spherical hydroxyapatite (s-HA and polyamide 66 (PA biocomposite (s-HA/PA was prepared, and its composition, mechanical properties, and cytocompatibility were characterized and evaluated. The results showed that HA distributed uniformly in the s-HA/PA matrix. Strong molecule interactions and chemical bonds were presented between the s-HA and PA in the composites confirmed by IR and XRD. The composite had excellent compressive strength in the range between 95 and 132 MPa, close to that of natural bone. In vitro experiments showed the s-HA/PA composite could improve cell growth, proliferation, and differentiation. Therefore, the developed s-HA/PA composites in this study might be used for tissue engineering and bone repair.

  5. Surface modification of polyamide thin film composite membrane by coating of titanium dioxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Thu Hong Anh Ngo

    2016-12-01

    Full Text Available In this paper, the coating of TiO2 nanoparticles onto the surface of a polyamide thin film composite nanofiltration membrane has been studied. Changes in the properties and separation performance of the modified membranes were systematically characterized. The experimental results indicated that the membrane surface hydrophilicity was significantly improved by the presence of the coated TiO2 nanoparticles with subsequent UV irradiation. The separation performance of the UV-irradiated TiO2-coated membranes was improved with a great enhancement of flux and a very high retention for removal of residual dye in an aqueous feed solution. The antifouling property of the UV-irradiated TiO2-coated membranes was enhanced with higher maintained flux ratios and lower irreversible fouling factors compared with an uncoated membrane.

  6. Thermal and mechanical properties of polyamide 6/compatibilizer/clay nano composites

    International Nuclear Information System (INIS)

    Agrawal, P.; Brito, G.F.; Cunha, C.T.C.; Araujo, E.M.; Melo, T.J.A.

    2010-01-01

    In this work, the thermal and mechanical properties of Polyamide 6 (PA6)/compatibilizer/clay (CL20A) nanocomposites were investigated. The nanocomposites were prepared in a counter-rotating twin screw extruder at 240 deg C and 50 rpm, and characterized by X-Ray Diffraction (XRD), Thermogravimetry (TG) and mechanical properties. XRD results showed that when the clay is mixed with PA6, the clay peak is shifted to lower 2θ angles, indicating that PA6 was intercalated between the clay platelets. For PA6/compatibilizer/clay system, the results indicated that a nanocomposite with exfoliated structure was formed. TG results showed that the thermal stability of PA6/CL20A and PA6/compatibilizer/CL20A was higher than that of neat PA6. The mechanical properties results showed that the addition of the compatibilizer to PA6/CL20A substantially increased the impact strength and decreased the stiffness. (author)

  7. Characterization of an aluminum-filled polyamide powder for applications in selective laser sintering

    International Nuclear Information System (INIS)

    Mazzoli, Alida; Moriconi, Giacomo; Pauri, Marco Giuseppe

    2007-01-01

    Solid free-form fabrication (SFF) techniques use layer-based manufacturing to create physical objects directly from computer-generated models. Using an additive approach to manufacture shapes, SFF systems join liquid, powder or sheet materials. Selective laser sintering (SLS) is a SFF technique by which parts are built layer-by-layer offering the key advantage of the direct manufacturing of functional parts. In SLS, a laser beam is traced over the surface of a tightly compacted powder made of thermoplastic material. In this paper is characterized a new aluminum-filled polyamide powder developed for applications in SLS. This material is promising for many applications that require a metallic look of the part, good finishing properties, high stiffness and higher part quality

  8. The surface characteristics of hyperbranched polyamide modified corncob and its adsorption property for Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hai, E-mail: linhai@ces.ustb.edu.cn [School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory on Resource-oriented Treatment of Industrial Pollutants, Beijing 100083 (China); Han, Shaoke; Dong, Yingbo; He, Yinhai [School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory on Resource-oriented Treatment of Industrial Pollutants, Beijing 100083 (China)

    2017-08-01

    Highlights: • An anion adsorbent was synthesized by hyperbranched polyamide modified corncob (HPMC). • The surface characteristics of samples (RCC, HPMC, HPMC-Cr) were studied. • Langmuir isotherm provided more fit and maximum adsorption capacity was 131.6 mg/g. • The adsorption process was chemisorption, controlled by intra-particle diffusion and film diffusion. • Adsorption is fast, stable, spontaneous and endothermic. - Abstract: A low-cost anion adsorbent for Cr(VI) effectively removing was synthesized by hyperbranched polyamide modified corncob (HPMC). Samples were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy, Fourier transform infrared (FTIR) and zeta potential analysis. Kinetics, isotherms and thermodynamics studies of HPMC for Cr(VI) adsorption were investigated in batch static experiments, in the temperature range of 25–45 °C, pH = 2.0. Results showed that the adsorption was rapid and stable, with the uptake capacity higher than 80% after 30 min. Adsorption behavior and rate-controlling mechanisms were analyzed using three kinetic models (pseudo-first order, pseudo-second order, intra-particle kinetic model). Kinetic studies showed that the adsorption of HPMC to Cr(VI) relied the pseudo-second-order model, and controlled both by the intra-particle diffusion and film diffusion. Equilibrium data was tested by Langmuir and Freundlich adsorption isotherm models. Langmuir model was more suitable to indicate a homogeneous distribution of active sites on HPMC and monolayer adsorption. The maximum adsorption capacity from the Langmuir model, q{sub max}, was 131.6 mg/g at pH 2.0 and 45 °C for HPMC. Thermodynamic parameters revealed spontaneous and endothermic nature of the Cr(VI) adsorption onto HPMC.

  9. Preliminary biocompatible evaluation of nano-hydroxyapatite/polyamide 66 composite porous membrane

    Directory of Open Access Journals (Sweden)

    Yili Qu

    2010-06-01

    Full Text Available Yili Qu1,3, Ping Wang1,3, Yi Man1, Yubao Li2, Yi Zuo2, Jidong Li21State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610064, China; 2Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064, China; 3These authors contributed equally to this workAbstract: Nano-hydroxyapatite/polyamide 66 (nHA/PA66 composite with good bioactivity and osteoconductivity was employed to develop a novel porous membrane with asymmetric structure for guided bone regeneration (GBR. In order to test material cytotoxicity and to investigate surface-dependent responses of bone-forming cells, the morphology, proliferation, and cell cycle of bone marrow stromal cells (BMSCs of rats cultured on the prepared membrane were determined. The polygonal and fusiform shape of BMSCs was observed by scanning electronic microscopy (SEM. The proliferation of BMSCs cultured on nHA/PA66 membrane tested by the MTT method (MTT: [3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazoliumbromide] was higher than that of negative control groups for 1 and 4 days’ incubation and had no significant difference for 7 and 11 days’ culture. The results of cell cycle also suggested that the membrane has no negative influence on cell division. The nHA/PA66 membranes were then implanted into subcutaneous sites of nine Sprague Dawley rats. The wounds and implant sites were free from suppuration and necrosis in all periods. All nHA/PA66 membranes were surrounded by a fibrous capsule with decreasing thickness 1 to 8 weeks postoperatively. In conclusion, the results of the in vitro and in vivo studies reveal that nHA/PA66 membrane has excellent biocompatibility and indicate its use in guided tissue regeneration (GTR or GBR.Keywords: hydroxyapatite/polyamide, barrier membrane, biocompatibility, guided bone regeneration

  10. Effect of acidic aqueous solution on chemical and physical properties of polyamide NF membranes

    Science.gov (United States)

    Jun, Byung-Moon; Kim, Su Hwan; Kwak, Sang Kyu; Kwon, Young-Nam

    2018-06-01

    This work was systematically investigated the effects of acidic aqueous solution (15 wt% sulfuric acid as model wastewater from smelting process) on the physical and chemical properties of commercially available nanofiltration (NF) polyamide membranes, using piperazine (PIP)-based NE40/70 membranes and m-phenylene diamine (MPD)-based NE90 membrane. Surface properties of the membranes were studied before and after exposure to strong acid using various analytical tools: Scanning Electron Microscopy (SEM), Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), contact angle analyzer, and electrophoretic light scattering spectrophotometer. The characterization and permeation results showed piperazine-based NE40/70 membranes have relatively lower acid-resistance than MPD-based NE90 membrane. Furthermore, density functional theory (DFT) calculation was also conducted to reveal the different acid-tolerances between the piperazine-based and MPD-based polyamide membranes. The easiest protonation was found to be the protonation of oxygen in piperazine-based monomer, and the N-protonation of the monomer had the lowest energy barrier in the rate determining step (RDS). The calculations were well compatible with the surface characterization results. In addition, the energy barrier in RDS is highly correlated with the twist angle (τD), which determines the delocalization of electrons between the carbonyl πCO bond and nitrogen lone pair, and the tendency of the twist angle was also maintained in longer molecules (dimer and trimer). This study clearly explained why the semi-aromatic membrane (NE40/70) is chemically less stable than the aromatic membrane (NE90) given the surface characterizations and DFT calculation results.

  11. Novel thermoplastic vulcanizates (TPVs based on silicone rubber and polyamide exploring peroxide cross-linking

    Directory of Open Access Journals (Sweden)

    K. Naskar

    2014-04-01

    Full Text Available Novel thermoplastic vulcanizates (TPVs based on silicone rubber (PDMS and polyamide (PA12 have been prepared by dynamic vulcanization process. The effect of dynamic vulcanization and influence of various types of peroxides as cross-linking agents were studied in detail. All the TPVs were prepared at a ratio of 50/50 wt% of silicone rubber and polyamide. Three structurally different peroxides, namely dicumyl peroxide (DCP, 3,3,5,7,7-pentamethyl 1,2,4-trioxepane (PMTO and cumyl hydroperoxide (CHP were taken for investigation. Though DCP was the best option for curing the silicone rubber, at high temperature it suffers from scorch safety. An inhibitor 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO was added with DCP to stabilize the radicals in order to increase the scorch time. Though CHP (hydroperoxide had higher half life time than DCP at higher temperature, it has no significant effect on cross-linking of silicone rubber. PMTO showed prolonged scorch safety and better cross-linking efficiency rather than the other two. TPVs of DCP and PMTO were made up to 11 minutes of mixing. Increased values of tensile strength and elongation at break of PMTO cross-linked TPV indicate the superiority of PMTO. Scanning electron micrographs correlate with mechanical properties of the TPVs. High storage modulus (E' and lower loss tangent value of the PMTO cross-linked TPV indicate the higher degree of cross-linking which is also well supported by the overall cross-link density value. Thus PMTO was found to be the superior peroxide for cross-linking of silicone rubber at high temperature.

  12. Toughening effect of multi-walled boron nitride nanotubes and their influence on the sintering behaviour of 3Y-TZP zirconia ceramics

    Czech Academy of Sciences Publication Activity Database

    Tatarko, Peter; Grasso, S.; Chlup, Zdeněk; Porwal, H.; Kasiarova, M.; Dlouhý, Ivo; Reece, M.J.

    2014-01-01

    Roč. 34, č. 7 (2014), s. 1829-1843 ISSN 0955-2219 EU Projects: European Commission(XE) 264526 - GLACERCO Institutional support: RVO:68081723 Keywords : Zirconia * Boron nitride nanotubes * Composite * Spark plasma sintering * Toughening mechanism Subject RIV: JI - Composite Materials Impact factor: 2.947, year: 2014

  13. Toughening behavior in ceramics associated with the transformation of tetragonal ZrO/sub 2/

    International Nuclear Information System (INIS)

    Becher, P.F.

    1986-01-01

    The contribution of the stress-induced phase transformation ZrO/sub 2/ to the fracture toughness of ceramics is described in terms of the zone size, the critical transformation stress and the influence of these parameters on the tetragonal to monoclinic transformation. For example in partially stabilized zirconia (PSZ), the ΔK/sub lC//sup T/ is shown to depend upon the martensite start (M/sub s/) temperature, which can be altered by the solute content and the particle or precipitate size. This behavior is consistent with the thermodynamics of the transformation. Experimental data correspond to the behavior predicted for various systems toughened by the addition of tetragonal ZrO/sub 2/ [e.g. PSZ and Al/sub 2/O/sub 3/-Z/sub 4/O/sub 2/(Y/sub 2/O/sub 3/). The stress required to transform the ZrO/sub 2/ is also modified by residual stresses due to the mismatch in matrix and particle (esp. thermal expansion) properties in the composite systems. The total residual stress acting on a particle is the sum of the particle's internal stress and the stress field of neighboring particles, and as a result, the total residual stress increases with volume fraction of ZrO/sub 2/ (V/sub f/). In the case of the Al/sub 2/O/sub 3/-ZrO/sub 2/ composites the pertinent stresses are tensile in character and thus promote the ZrO/sub 2/ transformation as V/sub f/ increases] For each level of Y/sub 2/O/sub 3/ in the ZrO/sub 2/, ΔK/sub lc//sup T/ then goes through a maximum with increase in V/sub f/ at a value of V/sub f/ where σ/sub R//sup T/ - σ/sub C//sup T/. The critical transformation stress is thus described for different levels of solute (e.g. Y/sub 2/O/sub 3/) in the ZrO/sub 2/. The dependence of ΔK/sub lc//sup T/ upon (σ/sub C//sup T/ - σ/sub R//sup T/) obtained is found to agree with the predicted behavior

  14. Strengthening and toughening of poly(L-lactide) composites by surface modified MgO whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Qin, Xiaopeng; Li, Cairong [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian; Ding, Shan [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2015-03-30

    Highlights: • The grafted PLLA chain on the surface of g-MgO whisker was ruled out by FTIR spectroscopy and TG/DTG analyses. • The excellent dispersion of g-MgO whiskers and the strong interfacial adhesion of g-MgO whiskers/PLLA composite were proved by FSEM. • Comparing to MgO particles and MgO whiskers, fibrous-like g-MgO whiskers are the most effective reinforcing and toughening fillers for PLLA. - Abstract: To improve both the strength and toughness of poly(L-lactide) (PLLA), fibrous-like MgO whiskers with diameters of 0.15–1 μm and lengths of 15–110 μm were prepared, and subsequently surface modified with L-lactide to obtain grafted MgO whiskers (g-MgO whiskers). The structures and properties of MgO whiskers and g-MgO whiskers were studied. Then, a series of MgO whiskers/PLLA and g-MgO whiskers/PLLA composites were prepared by solution casting method, for comparison, MgO particles/PLLA composite was prepared too. The resulting composites were evaluated in terms of hydrophilicity, crystallinity, dispersion of whiskers, interfacial adhesion and mechanical performance by means of polarized optical microscopy (POM), contact angle measurement, field emission scanning electron microscope (FSEM), transmission electron microscopy (TEM) and tensile testing. The results revealed that the crystallization rate and hydrophilicity of PLLA were improved by the introduction of MgO whiskers and g-MgO whiskers. The g-MgO whiskers can disperse more uniformly in and show stronger interfacial adhesion with the matrix than MgO whiskers as a result of the surface modification. Due to the bridge effect of the whiskers and the excellent interfacial adhesion between g-MgO whiskers and PLLA, g-MgO whiskers/PLLA composites exhibited remarkably higher strength, modulus and toughness compared to the pristine PLLA, MgO particles/PLLA and MgO whiskers/PLLA composites.

  15. Synthesis and characterization of novel polyamide-ethers based on bis-imidazole containing bulky aryl pendant groups

    Directory of Open Access Journals (Sweden)

    Seyed Mahdi Saadati

    2013-01-01

    Full Text Available A series of novel polyamide-ethers (PAEs based on bis-imidazole containing bulky aryl pendant groups was prepared by direct polycondensation of a diamine, 4-(1-(4-(4-(2-(4-aminophenyl-4,5-diphenyl-1H-imidazol-1-ylphenoxyphenyl-4,5-diphenyl-1H-imidazol-2-ylbenzenamine (DABI, and various dicarboxylic acids. All the resulting polyamide-ethers were amorphous with inherent viscosities ranged from 0.52 to 0.61 dL/g and were readily soluble in many organic solvents which could be solution-cast into transparent and tough films. The glass transition temperatures (Tg of these polymers were affected considerably by their chemical structure and ranged from 230 to 310 ºC. They had useful levels of thermal stability associated with relatively high temperatures of 10% weight loss (T10 in the range of 329-399 ºC in air atmosphere.

  16. Extraction and Characterization of Natural Dye from Green Walnut Shells and Its Use in Dyeing Polyamide: Focus on Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    Mohammad Mirjalili

    2013-01-01

    Full Text Available Extraction of dyes from walnut using Soxhlet apparatus has been studied. The color components extracted and isolated from walnut shells were characterized by column chromatography, thin layer chromatography (TLC, nuclear magnetic resonance (NMR, mass spectroscopy (MS, and infrared (IR techniques. Natural dye extract obtained from the walnut was used in dyeing polyamide fabrics with different mordants. The dyed fabrics were evaluated for antibacterial activity against pathogenic strains of Gram-positive (Staphylococcus aureus and Gram-negative (Escherichia coli bacteria. As such, the relationship between antibacterial activity and dye concentration is investigated. Durability of antibacterial activity to laundering is also discussed. Results indicate that the polyamide dyed with walnut displayed excellent antibacterial activity in the presence of ferric sulfate, cupric sulfate, and potassium aluminum sulfate and exhibited good and durable fastness properties.

  17. The influence of sterilisation on the macromechanical properties of polyamide fibre-reinforced PDMS composites for orthopaedic applications

    Czech Academy of Sciences Publication Activity Database

    Sedláček, R.; Suchý, Tomáš; Sucharda, Zbyněk; Balík, Karel; Sochor, M.; Šepitka, J.; Lukeš, J.

    2012-01-01

    Roč. 15, S1 (2012), s. 91-92 ISSN 1025-5842. [Congress of the Société de Biomécanique /37./. Toulouse, 16.10.2012-19.10.2012] R&D Projects: GA ČR(CZ) GAP108/10/1457 Institutional research plan: CEZ:AV0Z30460519 Keywords : composite material * polymer matrix * polyamide Subject RIV: JI - Composite Materials Impact factor: 1.393, year: 2012

  18. New polyamides based on 1,3-bis(4-carboxy phenoxy propane and hydantoin derivatives: synthesis and properties

    Directory of Open Access Journals (Sweden)

    Khalil Faghihi

    2010-04-01

    Full Text Available Six new polyamides 5a-f containing flexible trimethylene segments in the main chain were synthesized through the direct polycondensation reaction of 1,3-bis(4-carboxy phenoxy propane 3 with six derivatives of hydantoins 5a-f in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. The polycondensation reaction produced a series of novel polyamides in high yield with inherent viscosities between 0.30-0.47 dL/g. The resulted polymers were fully characterized by means of FT-IR, 1H-NMR spectroscopy, elemental analyses, inherent viscosity, solubility tests and gel permeation chromatography (GPC. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA and differential thermal gravimetry (DTG. The glass-transition temperatures of these polyamides were recorded between 130 and 155 oC by differential scanning calorimetry (DSC, and the 5% weight loss temperatures were ranging from 325 to 415 oC under nitrogen. 1,3-bis(4-Carboxy phenoxy propane 3 was prepared from the reaction of 4-hydroxy benzoic acid 1 with 1,3-dibromo propane 2 in the presence of NaOH solution.

  19. Utilization of rice husk ash as filler for polyamide 6 and ionizing radiation effect studies on this composite

    International Nuclear Information System (INIS)

    Ferro, Waldir Pedro

    2009-01-01

    In order to improve the dimensional stability, as well as, electrical, mechanical and thermal properties of polymers, new filler to this purpose has been developed. The mos applied filler to propitiate the features previously mentioned are the glass and carbon fibers, the mineral filler as the calcium carbonate, the talc and the micro glass sphere. The main aim of this work was to study the rice husk ash as filler for polyamide 6 and ionizing radiation effect studies on this composite, irradiated by electron beam at different doses, since it is constituted of at least 90% of silicon dioxide, and compared with the talc which is the most applied mineral filler. This comparison was made from a compound made through the refined rice husk ash and the polyamide 6 (PA 6), which is one of the main engineering plastic with applications in several productive areas. The samples were injected and irradiated in a electron accelerator. Afterwards, their mechanical and thermal properties were measured. It was also inject automotive parts to verify the processing of the PA 6 with CCA. The results showed that the use of the rice husk ash as filler for polyamide 6 composite is technically and economically viable. The irradiation of the studied composite (PA 6 with 30% of rice husk ash) did not provide any improvement for the mechanical and thermal properties previously appraised. (author)

  20. Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding.

    Science.gov (United States)

    Nagakura, Manamu; Tanimoto, Yasuhiro; Nishiyama, Norihiro

    2017-07-26

    The use of non-metal clasp denture (NMCD) materials may seriously affect the remaining tissues because of the low rigidity of NMCD materials such as polyamides. The purpose of this study was to develop a high-rigidity glass fiber-reinforced thermoplastic (GFRTP) composed of E-glass fiber and polyamide-6 for NMCDs using an injection molding. The reinforcing effects of fiber on the flexural properties of GFRTPs were investigated using glass fiber content ranging from 0 to 50 mass%. Three-point bending tests indicated that the flexural strength and elastic modulus of a GFRTP with a fiber content of 50 mass% were 5.4 and 4.7 times higher than those of unreinforced polyamide-6, respectively. The result showed that the physical characteristics of GFRTPs were greatly improved by increasing the fiber content, and the beneficial effects of fiber reinforcement were evident. The findings suggest that the injection-molded GFRTPs are adaptable to NMCDs because of their excellent mechanical properties.

  1. Effect of ultraviolet light irradiation and sandblasting treatment on bond strengths between polyamide and chemical-cured resin.

    Science.gov (United States)

    Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

    2014-01-01

    The aim of this study was to evaluate the effects of ultraviolet light (UV) irradiation and sandblasting treatment on the shear bond strength between polyamide and chemical-cured resin. Three types of commercial polyamides were treated using UV irradiation, sandblasting treatment, and a combining sandblasting and UV irradiation. The shear bond strength was measured and analyzed using the Kruskal-Wallis test (α=0.05). Comparing shear bond strengths without surface treatment, from 4.1 to 5.7 MPa, the UV irradiation significantly increased the shear bond strengths except for Valplast, whose shear bond strengths ranged from 5.2 to 9.3 MPa. The sandblasting treatment also significantly increased the shear bond strengths (8.0 to 11.4 MPa). The combining sandblasting and UV irradiation significantly increased the shear bond strengths (15.2 to 18.3 MPa) comparing without surface treatment. This combined treatment was considered the most effective at improving the shear bond strength between polyamide and chemical-cured resin.

  2. Improvement of surface wettability and interfacial adhesion of poly-(p-phenylene terephthalamide) by incorporation of the polyamide benzimidazole segment

    International Nuclear Information System (INIS)

    Cai Renqin; Peng Tao; Wang Fengde; Ye Guangdou; Xu Jianjun

    2011-01-01

    In order to investigate the effect of the polyamide benzimidazole group on the surface wettability and interfacial adhesion of fiber/matrix composites, surface features of two kinds of aramid fibers, poly (p-phenylene terephthalamide) fiber (Kevlar-49) and poly-(polyamide benzimidazole-co-p-phenylene terephthalamide) (DAFIII), have been analyzed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis (CAA) system, respectively. The results show that with the incorporation of the polyamide benzimidazole segment, more polar functional groups exist on DAFIII surface. The contact angles of water and diiodomethane on DAFIII surface get smaller. The surface free energy of DAFIII increases to 36.5 mJ/m 2 , which is 2.3% higher than that of Kevlar-49. In addition, DAFIII has a larger rough surface compared with that of Kevlar-49 due to different spinning processes. The interfacial shear strength (IFSS) of DAFIII/matrix composite is 25.7% higher than that of Kevlar-49/matrix composite, in agreement with the observed results from surface feature tests. SEM micrographs of failed micro-droplet specimens reveal a strong correlation between the fracture features and the observed test data.

  3. Binary Synergy Strengthening and Toughening of Bio-Inspired Nacre-like Graphene Oxide/Sodium Alginate Composite Paper.

    Science.gov (United States)

    Chen, Ke; Shi, Bin; Yue, Yonghai; Qi, Juanjuan; Guo, Lin

    2015-08-25

    A crucial requirement for most engineering materials is the excellent balance of strength and toughness. By mimicking the hybrid hierarchical structure in nacre, a kind of nacre-like paper based on binary hybrid graphene oxide (GO)/sodium alginate (SA) building blocks has been successfully fabricated. Systematic evaluation for the mechanical property in different (dry/wet) environment/after thermal annealing shows a perfect combination of high strength and toughness. Both of the parameters are nearly many-times higher than those of similar materials because of the synergistic strengthening/toughening enhancement from the binary GO/SA hybrids. The successful fabrication route offers an excellent approach to design advanced strong integrated nacre-like composite materials, which can be applied in tissue engineering, protection, aerospace, and permeable membranes for separation and delivery.

  4. Effects of intra- and inter-laminar resin content on the mechanical properties of toughened composite materials

    Science.gov (United States)

    Grande, Dodd H.; Ilcewicz, Larry B.; Avery, William B.; Bascom, Willard D.

    1991-01-01

    Composite materials having multiphase toughened matrix systems and laminate architectures characterized by resin-rich interlaminar layers (RIL) have been the subject of much recent attention. Such materials are likely to find applications in thick compressively loaded structures such as the keel area of commercial aircraft fuselages. The effects of resin content and its interlaminar and intralaminar distribution on mechanical properties were investigated with test and analysis of two carbon-epoxy systems. The RIL was found to reduce the in situ strengthening effect for matrix cracking in laminates. Mode 2 fracture toughness was found to increase with increasing RIL thickness over the range investigated, and Mode 1 interlaminar toughness was negligibly affected. Compressive failure strains were found to increase with increasing resin content for specimens having no damage, holes, and impact damage. Analytical tools for predicting matrix cracking of off-axis plies and damage tolerance in compression after impact (CAI) were successfully applied to materials with RIL.

  5. Toughening modification of poly(butylene terephthalate)/poly(ethylene terephthalate) blends by an epoxy-functionalized elastomer

    Science.gov (United States)

    Zhang, Weizhou; Wang, Kai; Yan, Wei; Guo, Weihong

    2017-10-01

    New toughened poly(butylene terephthalate) (PBT)/poly(ethylene terephthalate) (PET) (40/60 wt%) blends were obtained by melting with Glycidyl methacrylate grafted poly(ethylene octane) copolymer (POE-g-GMA), varying the POE-g-GMA content up to 20 wt%, in a twin-screw extruder, followed by injection molding. The influence of POE-g-GMA on the properties of the PBT/PET blends was investigated by mechanical testing, Fourier transform infrared (FT-IR) analysis, gel fractions analysis, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and scanning electronic microscopy (SEM). The mechanical testing results indicated that the incorporation of POE-g-GMA led to increases in the notched impact strength and decreases in the tensile strength, flexural strength, and flexural modulus. When POE-g-GMA content reached 20 wt%, the notched impact strength (8.0 kJ m-2) was achieved for the PBT/PET/POE-g-GMA blends. FT-IR results proved that some PBT/PET/POE-g-GMA copolymers were produced, which improved the compatibility between POE-g-GMA and the PBT/PET matrix. The extent of crosslinking was observed by gel fraction measurements. DMA results further testified chain-extending and micro-crosslink reactions occurred between POE-g-GMA and PBT/PET blends. In addition, the reactions induced by POE-g-GMA affected the crystallization behavior of PBT/PET blends obviously, as observed from DSC results. By means of SEM observation of the impact fracture surface morphology, and the discussion of the micro-crosslink reaction process between the epoxide-containing elastomers and PBT/PET matrix, the toughening mechanism was proposed to be taken into account the shear yielding of PBT/PET matrix and cavitation of elastomer particles.

  6. Double-Layer Surface Modification of Polyamide Denture Base Material by Functionalized Sol-Gel Based Silica for Adhesion Improvement.

    Science.gov (United States)

    Hafezeqoran, Ali; Koodaryan, Roodabeh

    2017-09-21

    Limited surface treatments have been proposed to improve the bond strength between autopolymerizing resin and polyamide denture base materials. Still, the bond strength of autopolymerizing resins to nylon polymer is not strong enough to repair the fractured denture effectively. This study aimed to introduce a novel method to improve the adhesion of autopolymerizing resin to polyamide polymer by a double layer deposition of sol-gel silica and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (AE-APTMS). The silica sol was synthesized by acid-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) as silica precursors. Polyamide specimens were dipped in TEOS-derived sol (TS group, n = 28), and exposed to ultraviolet (UV) light under O 2 flow for 30 minutes. UV-treated specimens were immersed in AE-APTMS solution and left for 24 hours at room temperature. The other specimens were either immersed in AE-APTMS solution (AP group, n = 28) or left untreated (NT group, n = 28). Surface characterization was investigated by fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). Two autopolymerizing resins (subgroups G and T, n = 14) were bonded to the specimens, thermocycled, and then tested for shear bond strength with a universal testing machine. Data were analyzed with one-way ANOVA followed by Tukey's HSD (α = 0.05). FTIR spectra of treated surfaces confirmed the chemical modification and appearance of functional groups on the polymer. One-way ANOVA revealed significant differences in shear bond strength among the study groups. Tukey's HSD showed that TS T and TS G groups had significantly higher shear bond strength than control groups (p = 0.001 and p < 0.001, respectively). Moreover, bond strength values of AP T were statistically significant compared to controls (p = 0.017). Amino functionalized TEOS-derived silica coating is a simple and cost-effective method for improving the bond strength between the autopolymerizing resin and polyamide

  7. Flame Retardant Polyamide Fibres: The Challenge of Minimising Flame Retardant Additive Contents with Added Nanoclays

    Directory of Open Access Journals (Sweden)

    Richard Horrocks

    2016-08-01

    Full Text Available This work shows that halogen-free, flame retarded polyamide 6 (PA6, fabrics may be produced in which component fibres still have acceptable tensile properties and low levels (preferably ≤10 wt % of additives by incorporating a nanoclay along with two types of flame retardant formulations. The latter include (i aluminium diethyl phosphinate (AlPi at 10 wt %, known to work principally in the vapour phase and (ii ammonium sulphamate (AS/dipentaerythritol (DP system present at 2.5 and 1 wt % respectively, believed to be condense phase active. The nanoclay chosen is an organically modified montmorillonite clay, Cloisite 25A. The effect of each additive system is analysed in terms of its ability to maximise both filament tensile properties relative to 100% PA6 and flame retardant behaviour of knitted fabrics in a vertical orientation. None of the AlPi-containing formulations achieved self-extinguishability, although the presence of nanoclay promoted lower burning and melt dripping rates. The AS/DP-containing formulations with total flame retardant levels of 5.5 wt % or less showed far superior properties and with nanoclay, showed fabric extinction times ≤ 39 s and reduced melt dripping. The tensile and flammability results, supported by thermogravimetric analysis, have been interpreted in terms of the mechanism of action of each flame retardant/nanoclay type.

  8. Tribological and mechanical behaviors of polyamide 6/glass fiber composite filled with various solid lubricants.

    Science.gov (United States)

    Li, Duxin; Xie, Ying; Li, Wenjuan; You, Yilan; Deng, Xin

    2013-01-01

    The effects of polytetrafluoroethylene (PTFE), graphite, ultrahigh molecular weight polyethylene (UHMWPE), and their compounds on mechanical and tribological properties of glass-fiber-reinforced polyamide 6 (PA6/GF) were studied. The polymeric materials were blended using twin-screw extruder and subsequently injection molded for test samples. Mechanical properties were investigated in terms of hardness, tensile strength, and impact strength. Friction and wear experiments were run under ambient conditions at a rotating speed of 200 rpm and load of 100 N. The morphologies of the worn surfaces were also observed with scanning electron microscope. The results showed that graphite could increase the tensile strength of PA6/GF-15 composite, but the material became soft. Graphite/UHMWPE complex solid lubricants were effective in increasing the already high impact strength of PA6/GF-15 composite. 5% PTFE gave the maximum reduction in the coefficient of friction. However, PTFE/UHMWPE complex solid lubricants were the best choice for improving both friction and wear behaviors due to the lower friction coefficient and mass wear rate. Moreover, the worn surface of PA6 composites revealed that adhesive wear, abrasive wear, and fatigue wear occurred in this study.

  9. Triclosan-immobilized polyamide thin film composite membranes with enhanced biofouling resistance

    Science.gov (United States)

    Park, Sang-Hee; Hwang, Seon Oh; Kim, Taek-Seung; Cho, Arah; Kwon, Soon Jin; Kim, Kyoung Taek; Park, Hee-Deung; Lee, Jung-Hyun

    2018-06-01

    We report on a strategy to improve biofouling resistance of a polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) membrane via chemically immobilizing triclosan (TC), known as a common organic biocide, on its surface. To facilitate covalent attachment of TC on the membrane surface, TC was functionalized with amine moiety to prepare aminopropyl TC. Then, the TC-immobilized TFC (TFC-TC) membranes were fabricated through a one-step amide formation reaction between amine groups of aminopropyl TC and acyl chloride groups present on the PA membrane surface, which was confirmed by high-resolution XPS. Strong stability of the immobilized TC was also confirmed by a hydraulic washing test. Although the TFC-TC membrane showed slightly reduced separation performance compared to the pristine control, it still maintained a satisfactory RO performance level. Importantly, the TFC-TC membrane exhibited excellent antibacterial activity against both gram negative (E. coli and P. aeruginosa) and gram positive (S. aureus) bacteria along with greatly enhanced resistance to biofilm formation. Our immobilization approach offers a robust and relatively benign strategy to control biofouling of functional surfaces, films and membranes.

  10. Preparation and characterisation of polyamide 11/montmorillonite (MMT) nanocomposites for use in angioplasty balloon applications

    International Nuclear Information System (INIS)

    Halim, Khairul Anwar A.; Farrell, Joseph B.; Kennedy, James E.

    2013-01-01

    With increased demands on catheter balloon functionality, there is an emphasis to blend new materials which can improve mechanical performance. Polymer nanocomposites were prepared by melt blending polyamide 11 (PA 11) with organically modified montmorillonite nanoclay. The effects of incorporating the nanoclay on the short-term mechanical properties of PA 11 were assessed using a design of experiments (DoEs) approach. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis techniques (DMA) were used to characterise the morphology of the nanocomposites. Design of experiments studies revealed that the optimum nanocomposites properties can be achieved by carefully controlling the melt compounding parameters. XRD and TEM data proved that exfoliated clay morphologies existed within the matrix at low clay loading (2%). Whereas the interaction between the polymer matrix and nanoclay was quantified in the DMA spectra, showed a significant increase in storage modulus (up to 80%). The reinforcing effect of nanoclay within the PA 11 was further investigated using mechanical testing, where significant increases in the ultimate tensile strength and strain at break of reinforced tri-layer balloon tubing were observed. - Highlights: • TEM reveals the coexistence of exfoliated and intercalated nanostructures. • Isothermal crystallisation studies found that the nano-clays reduced the crystallisation time. • Significant increase in the storage modulus was due to the reinforcing effect of the nano-clay platelets. • It was observed that the activation energy values decreased due to the presence of nanoclay

  11. Preparation and characterisation of polyamide 11/montmorillonite (MMT) nanocomposites for use in angioplasty balloon applications

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Khairul Anwar A. [Department of Polymer Engineering, Athlone Institute of Technology, Athlone (Ireland); School of Materials Engineering, Universiti Malaysia Perlis, Perlis (Malaysia); Farrell, Joseph B. [Department of Polymer Engineering, Athlone Institute of Technology, Athlone (Ireland); Kennedy, James E., E-mail: jkennedy@ait.ie [Department of Polymer Engineering, Athlone Institute of Technology, Athlone (Ireland)

    2013-12-16

    With increased demands on catheter balloon functionality, there is an emphasis to blend new materials which can improve mechanical performance. Polymer nanocomposites were prepared by melt blending polyamide 11 (PA 11) with organically modified montmorillonite nanoclay. The effects of incorporating the nanoclay on the short-term mechanical properties of PA 11 were assessed using a design of experiments (DoEs) approach. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis techniques (DMA) were used to characterise the morphology of the nanocomposites. Design of experiments studies revealed that the optimum nanocomposites properties can be achieved by carefully controlling the melt compounding parameters. XRD and TEM data proved that exfoliated clay morphologies existed within the matrix at low clay loading (2%). Whereas the interaction between the polymer matrix and nanoclay was quantified in the DMA spectra, showed a significant increase in storage modulus (up to 80%). The reinforcing effect of nanoclay within the PA 11 was further investigated using mechanical testing, where significant increases in the ultimate tensile strength and strain at break of reinforced tri-layer balloon tubing were observed. - Highlights: • TEM reveals the coexistence of exfoliated and intercalated nanostructures. • Isothermal crystallisation studies found that the nano-clays reduced the crystallisation time. • Significant increase in the storage modulus was due to the reinforcing effect of the nano-clay platelets. • It was observed that the activation energy values decreased due to the presence of nanoclay.

  12. Synergistic Flame Retardancy of Aluminium Dipropylphosphinate and Melamine in Polyamide 6

    Directory of Open Access Journals (Sweden)

    Linsheng Tang

    2013-01-01

    Full Text Available The synergistic flame retardancy of aluminium dipropylphosphinate (ADPP and melamine (ME in polyamide 6 (PA6 was studied by the limiting oxygen index (LOI measurement, the vertical burning test, and the cone calorimeter test, and the mechanism was also discussed by thermogravimetric and residual analyses. The experimental results indicated that there was obvious synergistic flame retardancy between ADPP and ME under their appropriate weight ratios. The thermogravimetric results and the analysis of the residues obtained in cone calorimeter test showed that ADPP and ADPP/ME played the role of flame retardance by gaseous- and condensed-phase mechanisms, where, on one hand, they were decomposed into nonvolatile aluminum phosphate and promoted the carbonization of PA6, and the formed intumescent layer resulted in flame retardancy by the barrier effect on heat, air, and decomposition products, and on the other hand, they were decomposed into volatile phosphorus compounds which bring about flame retardancy by flame inhibition. Using a combination of ADPP and ME improved charring of PA6 and raised the residual rate of P and Al, thus, improving the barrier effect in the condensed phase.

  13. Multifunctional glass fiber/polyamide composites with thermal energy storage/release capability

    Directory of Open Access Journals (Sweden)

    G. Fredi

    2018-04-01

    Full Text Available Thermoplastic composite laminates with thermal energy storage (TES capability were prepared by combining a glass fabric, a polyamide 12 (PA12 matrix and two different phase change materials (PCMs, i.e. a paraffinic wax microencapsulated in melamine-formaldehyde shells and a paraffin shape stabilized with carbon nanotubes. The melt flow index of the PA12/PCM blends decreased with the PCM concentration, especially in the systems with shape stabilized wax. Differential scanning calorimetry showed that, for the matrices with microcapsules, the values of enthalpy were approximately the 70% of the theoretical values, which was attributed to the fracture of some microcapsules. Nevertheless, most of the energy storage capability was preserved. On the other hand, much lower relative enthalpy values were measured on the composites with shape stabilized wax, due to a considerable paraffin leakage or degradation. The subsequent characterization of the glass fabric laminates highlighted that the fiber and void volume fractions were comparable for all the laminates except for that with the higher amount of shape stabilized wax, where the high viscosity of the matrix led to a low fiber volume fraction and higher void content. The mechanical properties of the laminates were only slightly impaired by PCM addition, while a more sensible drop of the elastic modulus, of the stress at break and of the interlaminar shear strength could be observed in the shape stabilized wax systems.

  14. CRYSTALLIZATION KINETICS OF POLYMERIC NANOCOMPOSITES BASED ON POLYAMIDE 12 MODIFIED BY Cr2O3 NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    E. S. Shapoval

    2014-09-01

    Full Text Available In situ polymerization method is used for obtaining polymeric composites based on polyamide12 matrix (PA 12, filled with Cr2O3 nanoparticles. The carried out researches result in synthesis method development for polymeric nanocomposites based on PA 12 matrix filled with nano-sized Cr2O3magnetic particles providing uniform embedding of the filler into polymeric matrix without formation of nanoparticles agglomerates. Mechanical tests on samples compression are carried out. It is shown that mechanical properties of polymeric composites (Young’s modulus, durability limit are decreased for 20-30 % as compared with not modified PA 12 synthesized by means of the chosen method. The influence of the filler on crystallization morphology and kinetics of polymeric nanocomposites is determined by electron microscopy and differential scanning calorimetry. The values of crystallization degree, crystallization rate constant for different supercooling intervals and parameters of Avrami equation are obtained. The initial nucleation is shown to be going on according to non-thermal mechanism, and nanoparticles are not the germs of crystallization. It is stated that nanoparticles are embedded into polymeric matrix and uniformly allocated in crystallites. Research results can find their application at creation of electric and magnetic fields, micro-sized mechanical devices, and at development of new materials for 3D printers.

  15. Selenopentathionic and Telluropentathionic Acids as Precursors for Formation of Semiconducting Layers on the Surface of Polyamide

    Directory of Open Access Journals (Sweden)

    Skirma Zalenkiene

    2007-01-01

    Full Text Available The layers of copper chalcogenides, which were formed on the surface of semihydrophilic polymer—polyamide 6 (PA using monoselenopentathionic H2SeS4O6 and monotelluropentathionic H2TeS4O6 acids as precursors of chalcogens, were characterized. Fourier transform infrared (FT-IR and UV spectroscopy were used to monitor the effect of chalcogens on the changes in structure of PA corresponding to the concentration of the precursor's solution and an exposure time. The IR spectra of modified PA were completely different from that of the initial PA. Further interaction of chalcogenized PA with copper (II/I salt solution leads to the formation of CuxS, CuxSe, CuxTe, and mixed –CuxS–CuySe and CuxS–CuyTe layers which have different electric transport properties. The surface properties of PA after treatment are studied using AFM and XRD. The electrical resistances of layers with various composition formed over a wide concentration range 0.01–0.5 mol⋅dm−3 of precursor's solution were measured. Variation in the conductivity of layers of Cu–Se–S and Cu–Te–S on the surface of PA shows an evident increase with the increasing of the mass fraction of selenium or tellurium.

  16. Tensile fracture behaviors of T-ZnOw/polyamide 6 composites

    International Nuclear Information System (INIS)

    Shi Jing; Wang Yong; Liu Li; Bai Hongwei; Wu Jun; Jiang Chongxi; Zhou, Zuowan

    2009-01-01

    As a part of serial work about the application of tetra-needle-shaped zinc oxide whisker (T-ZnOw) in polymer composites, this work is focused on the crystallization and tensile fracture behaviors of T-ZnOw/polyamide 6 (T-ZnOw/PA6) composites. Our results show that the addition of T-ZnOw improves the composites tensile strength greatly. For virgin PA6, the stress-strain curve exhibits double-yielding phenomenon. Surface modified T-ZnOw reinforced PA6 composites exhibit higher yield stress and smaller strain-to-fracture compared with virgin PA6. The morphologies of tensile-fractured surfaces show that, addition of T-ZnOw changes the fracture mode from crazing-tearing/brittle fracture mode of virgin PA6 into fibrillation/brittle fracture mode of PA6 composites. Especially, the fracture process of T-ZnOw in composites during the tensile test has been characterized by scanning electronic microscope (SEM) and the corresponding reinforcement mechanism has been discussed.

  17. Study on thermal stability and chemical structure of polyamide blended with small amount of Cu

    International Nuclear Information System (INIS)

    Arai, Tsuyoshi; Ueno, Tomonaga; Kajiya, Takafumi; Ishikawa, Tomoyuki; Takeda, Kunihiko

    2007-01-01

    The thermal stability and the chemical structure of Polyamide 66 (PA66) blended with a small amount of copper have been studied. The thermal degradation of the blend with 35 ppm or more of copper was restrained and no strong influence of the concentration of copper was observed. The molecular weight of PA66 decreased by the thermal aging process but the amount of decrease of the blend was smaller than that of the non-blend. The water uptake of the blend increased. The chemical structure, which was observed by IR and NMR, changed slightly by blending with copper after aging at higher temperatures. Multiple items influenced the thermal stability of PA66 blended with a small amount of copper instead of just one. Namely, the main chain of PA66 is cut by heat and the degree of the cut is restrained by the copper. The diffusion time of copper atoms that disperse uniformly in the PA66 matrix is short enough to cover the individual amide groups and the effect enlarges the entire configuration of the PA66 chain to enhance the thermal stability. (author)

  18. Evaluation of the permeability of microporous membranes polyamide 6 / clay bentonite for water-oil separation

    International Nuclear Information System (INIS)

    Medeiros, P.S.S.; Medeiros, K.M.; Araujo, E.M.; Lira, H.L.

    2014-01-01

    The petroleum refining industries have faced major problems in relation to the treatment of their effluents before disposal into the environment. Among the conventional technologies treatment of these effluents, the process of oil-water separation by means of membranes has been extensively used, for having enormous potentiality. Therefore, in this study, hybrid membranes of polyamide 6/ bentonite clay were produced by the technique of phase inversion and by precipitation of the solution from the nanocomposites obtained by melt intercalation. The clay was organically modified with the quaternary ammonium salt (Cetremide®). The nanocomposites were obtained from (PA6) with untreated (AST) and treated clay (ACT), which were subsequently characterized by X-ray diffraction (XRD). Already membranes were characterized by XRD, scanning electron microscopy (SEM) and flow measurements. From the XRD results, it was observed an exfoliated and/or partially exfoliated structure for the nanocomposites and for the membranes. From SEM images it was observed that the presence of AST and ACT clays in the polymeric matrix caused changes in membrane morphology and pore formation. The flow with distilled water in the membranes showed a decrease initially and then followed by stability. All membranes tested in the process of separating emulsions of oil in water, particularly those of nanocomposites obtained a significant reduction of oil concentration in the permeate, thus showing that these membranes have a great potential to be applied to the water-oil separation. (author)

  19. Tribological and Mechanical Behaviors of Polyamide 6/Glass Fiber Composite Filled with Various Solid Lubricants

    Directory of Open Access Journals (Sweden)

    Duxin Li

    2013-01-01

    Full Text Available The effects of polytetrafluoroethylene (PTFE, graphite, ultrahigh molecular weight polyethylene (UHMWPE, and their compounds on mechanical and tribological properties of glass-fiber-reinforced polyamide 6 (PA6/GF were studied. The polymeric materials were blended using twin-screw extruder and subsequently injection molded for test samples. Mechanical properties were investigated in terms of hardness, tensile strength, and impact strength. Friction and wear experiments were run under ambient conditions at a rotating speed of 200 rpm and load of 100 N. The morphologies of the worn surfaces were also observed with scanning electron microscope. The results showed that graphite could increase the tensile strength of PA6/GF-15 composite, but the material became soft. Graphite/UHMWPE complex solid lubricants were effective in increasing the already high impact strength of PA6/GF-15 composite. 5% PTFE gave the maximum reduction in the coefficient of friction. However, PTFE/UHMWPE complex solid lubricants were the best choice for improving both friction and wear behaviors due to the lower friction coefficient and mass wear rate. Moreover, the worn surface of PA6 composites revealed that adhesive wear, abrasive wear, and fatigue wear occurred in this study.

  20. Thermal conductivity of plasma modified polyethylene terephthalate and polyamide-6 layers

    Directory of Open Access Journals (Sweden)

    G. Kalacska

    2016-05-01

    Full Text Available Tribological performance of the materials greatly depends on the temperature of the contacting zones and surfaces and hence on the heat conducting behaviour of the materials. Heat conduction of polymers is, however, greatly affected even by a very narrow (few tens of nm modified layer formed on the surface after subjecting the polymer to plasma treatment. In this article the heat flow inhibiting properties of plasma modified surface layers were investigated on polyethylene terephthalate (PET and polyamide-6 (PA6 engineering polymers. Nitrogen Plasma Immersion Ion Implantation gave rise to compositional and structural changes of the polymers in a depth of 110 nm. It was found that even this thin layer exhibited significant heat flow inhibiting effect. The modified layer considerably decreased the thermal conductivity coefficient of the treated polymer and resulted in a reduced heat transmission for PET and PA6 by 33 and 28%, respectively. This new information supports and is in accordance with the former tribological results about extra friction heat generation experienced under NPIII surface layer of PA6 and PET during dry sliding.

  1. Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

    Science.gov (United States)

    Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

    2013-05-10

    Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

  2. Generation of conductivity through transfer charge properties, for polyesters and polyamides with characteristic functional groups

    Science.gov (United States)

    Gonzalez, Carmen; Tagle, Luis Hernan; Terraza, Claudio A.; Barriga, Andres; Cabrera, A. L.; Volkmann, Ulrich G.

    2011-03-01

    Electro-optic properties of σ -conjugated polymers, as polysilylene; are associated with electron conjugation in the silicon atom, which allows a significant delocalization of electrons along of the chain. Thus, the conductivity is intimately connected to the mobility of charge carriers, which in turn depends on the structure and morphology of the system. We report the characterization of polyesters (PEFs) and polyamides (PAFs). Film thicknesses were obtained by ellipsometry. The vibration frequencies of the groups were determined by FT-IR and corroborated by Raman spectroscopy. Structural information was obtained from X-Ray diffraction (XRD). The structural and surface morphology were studied by scanning electron microscope (SEM). Electrical conductivity of the polymers was measured before and after exposure to iodine vapor, for films of different thicknesses. Morphological differentiation was studied by energy dispersive microscopy (EDX), showing a regular distribution of iodine within the polymer. Preliminary conductivity measurements showed adverse effects when oxidation of the polymer films is induced These effects are related to a certain grade of disorder within the system

  3. Preparation of Polyamide-6 Submicrometer-Sized Spheres by In Situ Polymerization.

    Science.gov (United States)

    Zhao, Xingke; Xia, Housheng; Fu, Xubing; Duan, Jianping; Yang, Guisheng

    2015-11-01

    Polyamide-6 (PA6) submicron-sized spheres are prepared by two steps: (1) anionic ring-opening polymerization of ε-caprolactam in the presence of poly(ethylene glycol)-block-poly-(propylene glycol)-block-poly(ethylene glycol)(PEG-b-PPG-b-PEG) and (2) separation of PA6 spheres by dissolving PEG-b-PPG-b-PEG from the prepared blends. The PA6 microspheres obtained are regular spherical, with diameter ranging from 200 nm to 2 μm and narrow size distribution, as confirmed by scanning electron microscopy. By comparison with PA6/PS and PA6/PEG systems, it is denominated that the PEG blocks in PEG-b-PPG-b-PEG can effectively reduce the surface tension of PA6 droplets and further decrease the diameter of the PA6 microspheres. The PPG block in PEG-b-PPG-b-PEG can prevent the PA6 droplets coalescing with each other, and isolated spherical particles can be obtained finally. The phase inversion of the PA6/PEG-b-PPG-b-PEG blends occurs at very low PEG-b-PPG-b-PEG content; the PEG-b-PPG-b-PEG phase can be removed by water easily. The whole experiment can be finished in a short time (approximately in half an hour) without using any organic solvents; it is an efficient strategy for the preparation of submicron-sized PA6 microspheres. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Control of biofouling on reverse osmosis polyamide membranes modified with biocidal nanoparticles and antifouling polymer brushes

    KAUST Repository

    Rahaman, Md. Saifur

    2014-01-01

    Thin-film composite (TFC) polyamide reverse osmosis (RO) membranes are prone to biofouling due to their inherent physicochemical surface properties. In order to address the biofouling problem, we have developed novel surface coatings functionalized with biocidal silver nanoparticles (AgNPs) and antifouling polymer brushes via polyelectrolyte layer-by-layer (LBL) self-assembly. The novel surface coating was prepared with polyelectrolyte LBL films containing poly(acrylic acid) (PAA) and poly(ethylene imine) (PEI), with the latter being either pure PEI or silver nanoparticles coated with PEI (Ag-PEI). The coatings were further functionalized by grafting of polymer brushes, using either hydrophilic poly(sulfobetaine) or low surface energy poly(dimethylsiloxane) (PDMS). The presence of both LBL films and sulfobetaine polymer brushes at the interface significantly increased the hydrophilicity of the membrane surface, while PDMS brushes lowered the membrane surface energy. Overall, all surface modifications resulted in significant reduction of irreversible bacterial cell adhesion. In microbial adhesion tests with E. coli bacteria, a normalized cell adhesion in the range of only 4 to 16% on the modified membrane surfaces was observed. Modified surfaces containing silver nanoparticles also exhibited strong antimicrobial activity. Membranes coated with LBL films of PAA/Ag-PEI achieved over 95% inactivation of bacteria attached to the surface within 1 hour of contact time. Both the antifouling and antimicrobial results suggest the potential of using these novel surface coatings in controlling the fouling of RO membranes. © The Royal Society of Chemistry 2014.

  5. Natural organic matter interactions with polyamide and polysulfone membranes: Formation of conditioning film

    KAUST Repository

    Gutierrez, Leonardo

    2015-03-31

    A conditioning film changes the physicochemical properties of the membrane surface and strongly affects subsequent fouling behavior. Results from this Atomic Force Microscopy study indicate that Natural Organic Matter (NOM) characteristics, membrane surface properties, and solution chemistry are fundamental during conditioning film formation. Repulsive forces were observed between HUM (humic-NOM) and Polyamide (PA) or Polysulfone (PS) membranes during approach in Na+ and Ca2+ solutions. However, repulsive and attractive forces were randomly recorded during BIOP (biopolymer-NOM) approach to both membranes, possibly caused by low electrostatic repulsion, hydrogen bonding, and presence of chemically/physically heterogeneous regions on membrane surfaces. During retracting, Ca2+ ions increased HUM adhesion to PA and PS membrane, indicating cation bridging/complexation as dominant interacting mechanism for this isolate. BIOP adsorption on PS and PA membrane was stronger than HUM under similar solution conditions, where hydrogen bonding would play an important role. Additionally, irrespective of solution conditions, higher adhesion energy was recorded on PS than on PA membrane for both NOM isolates, indicating membrane hydrophobicity as an important interacting factor. Results from this research will advance our understanding of conditioning film formation for NOM isolates and membranes of different physicochemical characteristics.

  6. Synergistically improved thermal conductivity of polyamide-6 with low melting temperature metal and graphite

    Directory of Open Access Journals (Sweden)

    Y. C. Jia

    2016-08-01

    Full Text Available Low melting temperature metal (LMTM-tin (Sn was introduced into polyamide-6 (PA6 and PA6/graphite composites respectively to improve the thermal conductivity of PA6 by melt processing (extruding and injection molding. After introducing Sn, the thermal conductivity of PA6/Sn was nearly constant because of the serious agglomeration of Sn. However, when 20 wt% (5.4 vol% of Sn was added into PA6 containing 50 wt% (33.3 vol% of graphite, the thermal conductivity of the composite was dramatically increased to 5.364 versus 1.852 W·(m·K–1 for the PA6/graphite composite, which suggests that the incorporation of graphite and Sn have a significant synergistic effect on the thermal conductivity improvement of PA6. What is more, the electrical conductivity of the composite increased nearly 8 orders of magnitudes after introducing both graphite and Sn. Characterization of microstructure and energy dispersive spectrum analysis (EDS indicates that the dispersion of Sn in PA6/graphite/Sn was much more uniform than that of PA6/Sn composite. According to Differential Scanning Calorimetry measurement and EDS, the uniform dispersion of Sn in PA6/graphite/Sn and the high thermal conductivity of PA6/graphite/Sn are speculated to be related with the electron transfer between graphite and Sn, which makes Sn distribute evenly around the graphite layers.

  7. Processing – morphology – property relationships of polyamide 6/polyethylene blend–clay nanocomposites

    Directory of Open Access Journals (Sweden)

    R. Scaffaro

    2013-10-01

    Full Text Available In this work, we studied the effect of the method of preparation and of reprocessing on the morphology and, consequently, on the physical properties of polyamide 6 (PA6/ high density polyethylene (HDPE-clay nanocomposite blends in the presence of different compatibilizers. In particular, the nanocomposites were obtained by melt mixing using a corotating twin screw extruder (E1. The blends thus obtained were re-extruded (E2 under the same operating conditions. Moreover, blends with the same final composition were produced using a masterbatch of the compatibilizer with the clay prepared in a separated stage in a batch mixer (MB. All the materials were characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM and X-ray diffractometry (XRD analyses. In addition, the rheological behaviour and the, tensile and impact, properties were evaluated. The XRD and TEM analysis showed that re-extrusion slightly improves the morphology of the nanocomposites. A further improvement of the morphology, in terms of lower clay dimension and better dispersion, was observed in the MB blends. The results of the mechanical tests showed that reprocessing (E2 induced an increase of all the properties for all the three systems. A further general increase of the mechanical properties was showed by the MB blends.

  8. Diffuse plasma treatment of polyamide 66 fabric in atmospheric pressure air

    International Nuclear Information System (INIS)

    Li, Lee; Peng, Ming-yang; Teng, Yun; Gao, Guozhen

    2016-01-01

    Graphical abstract: - Highlights: • A cylindrical-electrode nanosecond-pulse diffuse-discharge reactor is presented. • Large-scale non-thermal plasmas were generated steadily in atmospheric air. • Treated PA66 fabric is etched with oxygen-containing group increases. • The hydrophily of treated PA66 fabric improves effectively. • Extending the treatment time is a method to reduce the treatment frequency. - Abstract: The polyamide 66 (PA66) fabrics are hard to be colored or glued in industrial production due to the poor hydrophily. Diffuse plasma is a kind of non-thermal plasma generated at atmospheric pressure in air. This paper proposes that large-scale diffuse plasma generated between wire electrodes can be employed for improving the hydrophily of PA66 fabrics. A repetitive nanosecond-pulse diffuse-discharge reactor using a cylindrical wire electrode configuration is presented, which can generate large-scale non-thermal plasmas steadily at atmospheric pressure without any barrier dielectric. Then the reactor is used to treat PA66 fabrics in different discharge conditions. The hydrophilicity property of modified PA66 is measured by wicking test method. The modified PA66 is also analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to prove the surface changes in physical microstructure and chemical functional groups, respectively. What's more, the effects of treatment time and treatment frequency on surface modification are investigated and discussed.

  9. Chlorine-Resistant Polyamide Reverse Osmosis Membrane with Monitorable and Regenerative Sacrificial Layers.

    Science.gov (United States)

    Huang, Hai; Lin, Saisai; Zhang, Lin; Hou, Li'an

    2017-03-22

    Improving chlorine stability is a high priority for aromatic polyamide (PA) reverse osmosis (RO) membranes especially in long-term desalination. In this Research Article, PA RO membranes of sustainable chlorine resistance was synthesized. Glycylglycine (Gly) was grafted onto the membrane surface as a regenerative chlorine sacrificial layer, and the zeta-potential was used to monitor the membrane performance and to conduct timely regeneration operations for chlorinated Gly. The Gly-grafted PA membrane exhibited ameliorative chlorine resistance in which the N-H moiety of glycylglycine served as sacrificial pendants against chlorine attacks. Cyclic chlorination experiments, combined with FT-IR and XPS analysis, were carried out to characterize the membrane. Results indicated that the resulting N-halamines could be fast regenerated by a simple alkaline reduction step (pH 10). A synchronous relationship between the zeta-potential and the chlorination extent of the sacrificial layer was observed. This indicated that the zeta-potential can be used as an on-site sensor to conduct a timely regeneration operation. The intrinsic mechanism of the surface sacrificial process was also studied.

  10. Reinforced nanohydroxyapatite/polyamide66 scaffolds by chitosan coating for bone tissue engineering.

    Science.gov (United States)

    Huang, Di; Zuo, Yi; Zou, Qin; Wang, Yanying; Gao, Shibo; Wang, Xiaoyan; Liu, Haohuai; Li, Yubao

    2012-01-01

    High porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n-HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n-HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast-like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n-HA/PA66 scaffolds. The CS reinforced n-HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair. Copyright © 2011 Wiley Periodicals, Inc.

  11. Viscosity of nanoconfined polyamide-6,6 oligomers: atomistic reverse nonequilibrium molecular dynamics simulation.

    Science.gov (United States)

    Eslami, Hossein; Müller-Plathe, Florian

    2010-01-14

    Our new simulation scheme in isosurface-isothermal-isobaric ensemble [Eslami, H.; Mozaffari, F.; Moghadasi, J.; Müller-Plathe, F. J. Chem. Phys. 2008, 129, 194702], developed to simulate confined fluids in equilibrium with bulk, is applied to simulate polyamide-6,6 oligomers confined between graphite surfaces. The reverse nonequilibrium molecular dynamics simulation technique is employed to shear the graphite surfaces. In this work, six confined systems, with different surface separations, as well as the bulk fluid are simulated. Our results show a viscosity increase with respect to the bulk fluid, with decreasing distance between surfaces. Also, the calculated viscosities of the confined systems show an oscillatory behavior with maxima corresponding to well-formed layers between the surfaces. We observe a substantial slip at the surfaces, with the slip length depending on the shear rate and on the slit width. The slip length and the slip velocity show oscillatory behavior with out-of-phase oscillations with respect to the solvation force oscillations. Moreover, the temperature difference between coldest and hottest parts of the simulation box depends on the shear rate and on the layering effect (solvation force oscillations). An analysis of oligomer deformation under flow shows preferential alignment of oligomers parallel to the surfaces with increasing shear rate.

  12. Microporous membranes from polyamide 6/national clay nanocomposites - Part 2: microstructural and permeability evaluation

    International Nuclear Information System (INIS)

    Leite, Amanda M.D.; Araujo, Edcleide M.; Lira, Helio de L.; Paz, Rene Anisio da; Medeiros, Vanessa da Nobrega

    2014-01-01

    Organic/inorganic hybrid membranes of polyamide 6 and mineral clay containing layers of silicate were prepared and compared to those of the pure polymer. Use was made of an as-received sodium clay from industry and another organophilized with ammonium quaternary salts (Dodigen and Cetremide). The salts make the clays surface hydrophobic and improve their incorporation into the polymer matrix in the molten state. Membranes were prepared with these nanocomposites using the immersion-precipitation technique with formic acid as a solvent, and precipitation in a water bath as non-solvent. The acid concentration in the solution containing the polymer and the hybrids was varied to study its influence in morphology and permeability of the membranes. An asymmetric morphology consisting of a filter skin and a porous support was observed, with pores both on the surface and in the cross section being affected by the different salts. This asymmetric morphology was also affected significantly by the acid concentration, with thicker filter skins for higher concentrations. The acid concentration affected the pores size and their distribution. The clay particles probably acted as a barrier to the flow. The permeating flux for the two acid concentrations varied as a function of the distinct morphologies. (author)

  13. Polyamide Microparticles Containing Vitamin C by Interfacial Polymerization: An Approach by Design of Experimentation

    Directory of Open Access Journals (Sweden)

    Lionel Ripoll

    2016-11-01

    Full Text Available Vitamin C is widely use in cosmetics and pharmaceutics products for its active properties. However ascorbic acid shows unfavourable chemical instability such as oxidation leading to formulation problems. Therefore, carriers, such as micro- and nanoparticles, have been widely investigated as delivery systems for vitamin C to improve its beneficial effects in skin treatment. However, none of the previous studies have been able to produce microparticles with a high encapsulation entrapment of vitamin C. The aim of the present study is to use an experimental design to optimize the synthesis of polyamide microparticles for the delivery of ascorbic acid. The effect of four formulation parameters on microparticles properties (size and morphology, encapsulation efficiency and yield, release kinetics were investigated using a surface response design. Finally, we were able to obtain stable microparticles containing more than 65% of vitamin C. This result confirms the effectiveness of using design of experiments for the optimisation of microparticle formulation and supports the proposal of using them as candidate for the delivery of vitamin C in skin treatment.

  14. Vieillissement du polyamide 11 utilisé dans les conduites flexibles : influence de la composition du fluide transporté Influence of the Chemical Nature of the Environment on the Aging of Polyamide 11 Used for Offshore Flexible Pipes

    Directory of Open Access Journals (Sweden)

    Ubrich E.

    2006-11-01

    Full Text Available Le polyamide 11 est utilisé comme gaine d'étanchéité interne des conduites flexibles de transport de produits pétroliers. Dans certaines conditions d'utilisation, celui-ci subit une dégradation de ses propriétés mécaniques et physico-chimiques initiales. Des échanges de matières s'établissent entre le matériau et le fluide transporté : des composés constitutifs du fluide (eau, hydrocarbures peuvent être absorbés par le polyamide tandis que le principal additif du matériau (le plastifiant est extrait. Cette étude, entreprise pour déterminer l'influence de la composition du milieu chimique sur les propriétés du polyamide 11, a permis : 1 De développer une nouvelle méthode d'analyse des matières diffusant dans le polyamide 11. Le principe de cette méthode consiste à réaliser une thermodésorption des différentes matières présentes dans le polymère et à les analyser en ligne par spectrométrie de masse à moyenne résolution (résolution = 3000. Cette méthode permet l'analyse quantitative simultanée du plastifiant résiduel, de l'eau et des hydrocarbures absorbés ainsi que la détermination de la répartition par familles chimiques de ces hydrocarbures. 2 De proposer un modèle prédictif du vieillissement du polyamide 11 dans des milieux modèles constitués d'eau, d'une coupe gazole principalement aliphatique et d'une coupe gazole principalement aromatique. La composition de ces différents milieux de vieillissement a été choisie à l'aide d'un plan d'expériences appliqué aux mélanges. L'influence de l'eau sur les propriétés mécaniques (diminution de l'allongement à la rupture et physico-chimiques (diminution de la masse moléculaire moyenne et augmentation du taux de cristallinité a été mise en évidence. Par ailleurs, quel que soit le milieu de vieillissement, à 140°C, le plastifiant est extrait du polyamide. L'influence du milieu aromatique sur la plastification du matériau a été d

  15. Mechanical and rheological properties of nanocomposites of polyamide 6 with national organoclay; Propriedades mecanicas e reologicas de nanocompositos de poliamida 6 com argila organofilica nacional

    Energy Technology Data Exchange (ETDEWEB)

    Paz, Rene Anisio da; Leite, Amanda Melissa Damiao; Araujo, Edcleide Maria; Melo, Tomas Jeferson Alves de, E-mail: rene@cct.ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Pessan, Luiz Antonio; Passador, Fabio Roberto [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2013-07-01

    Nanocomposites of polyamide 6 with organoclay were prepared by melt intercalation and their rheological and mechanical properties were studied. The clay was treated with the quaternary ammonium salt (Cetremide) and characterized by Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed the incorporation of salt in the clay and its organophilization. A master was prepared with PA6/clay (1:1) by weight and this was added to the pure polyamide 6 to reach the nominal proportion of 3% of clay, using a co-rotational twin screw extruder. The samples were molded by injection and characterized by: capillary rheometry, XRD, TEM and mechanical testing (tensile and impact). The results of capillary rheometry showed that the presence of organoclay in the PA6 increased the viscosity of the systems. With XRD and TEM, it was verified that all systems presented predominantly exfoliated structure. The tensile properties of the nanocomposites were better than those of pure polyamide 6. (author)

  16. Comparative study by TG and DSC Of membranes polyamide66/bentonite clay nanocomposite; Estudo comparativo por TG e DSC de membranas de nanocompositos poliamida66/argila bentonitica

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, K.M. de; Kojuch, L R; Araujo, E M; Lira, H.L., E-mail: keilamm@ig.com.b [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Lima, F [Universidade Estadual da Paraiba (UEPB), Campina Grande, PB (Brazil). Dept. de Quimica

    2010-07-01

    In this study, it was obtained membranes of nanocomposites polyamide66 with 3 and 5% bentonite clay consists of silicates in layers from the interior of Paraiba. The clay was treated with a quaternary ammonium salt in order to make it organophilic. The membranes were prepared by phase inversion technique from the nanocomposites in solution. The clays were characterized by X-ray diffraction (XRD) and thermogravimetry (TG). Also the membranes were characterized by differential scanning calorimetry (DSC) and TG. The XRD and TG confirmed the presence of salt in the clay and thermal stability of the treated clay. For DSC, it was observed that there was no change in melting temperature of the membranes of nanocomposites compared to membrane pure polyamide66. By TG, it was found that the decomposition of the membranes of polyamide66 with treated clay were higher compared with the untreated clay. (author)

  17. Effects of hydrophilic solvent and oxidation resistance post surface treatment on molecular structure and forward osmosis performance of polyamide thin-film composite (TFC) membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Qibo; Xu, Yangyu [School of Environment, Tsinghua University, Beijing 100084 (China); Shen, Jianquan [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Haijun, E-mail: yanghj@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Lu, E-mail: zhoulu@tsinghua.edu.cn [School of Environment, Tsinghua University, Beijing 100084 (China)

    2015-11-30

    Graphical abstract: - Highlights: • NMP promotes swelling of polyamide, which enhances the TFC FO membrane water flux. • Electron-withdrawing carboxyl groups reduce the activity of polyamide molecules. • TMC and oxalic acid can improve the oxidation resistance properties of the FO membrane. • Oxalic acid and EDC improve the FO membrane separation performance significantly. - Abstract: In this article, novel hydrophilic solvents and antioxidants were used to post-treat aromatic polyamide thin-film composite (TFC) hollow fiber forward osmosis (FO) membranes. The effects of trimesoyl chloride (TMC) and oxalic acid on the structure of polyamide skin layer were investigated using ATR-FTIR and XPS analyses. Pure water flux and rejection of salts were detected using 2 M NaCl solution as draw solutions in FO processes. The results demonstrated that hydrophilic solvent N-methyl pyrrolidone (NMP) enhanced the water flux and kept a high salt retention of the TFC FO membrane. TMC and oxalic acid were both found to improve the oxidation resistance properties of the skin layer of TFC membrane because the electron-withdrawing carboxyl groups reduced the activity of polyamide molecular. The effects of the oxalic acid and carbodiimide on the molecular structures and the FO water flux of the polyamide TFC membranes were more marked than those of TMC. The novel TFC FO membrane treated by oxalic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) exhibited a high level of water flux (20.33 L m{sup −2} h{sup −1}), and the rates of salt rejection and salt reverse rejection were higher by 50% and 83%, respectively.

  18. Bonding properties of acrylonitrile butadiene rubber with polyamide mediated by a functional layer of silane coupling agent

    International Nuclear Information System (INIS)

    Sang, J.; Aisawa, S.; Hirahara, H.; Mori, K.

    2017-01-01

    This study demonstrates that coating layers, expected to be formed as self-assembled monolayers, of silane coupling agents can act as adhesion layers as the hydrogenated acrylonitrile butadiene rubber (HNBR) and polyamide (PA6) plate interfaces. The resulting PA6/HNBR joints showed excellent adhesion properties with cohesive failure and the interfaces were jointed through chemical bonds, which were confirmed by swelling tests. The surfaces and bonding properties of rubber and PA6 were studied by means of peel tests, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nanoscale infrared microscopy and chemical imaging (AFM-IR). (authors)

  19. Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants

    OpenAIRE

    Abe, Yutaka; Mutsuga, Motoh; Ohno, Hiroyuki; Kawamura, Yoko; Akiyama, Hiroshi

    2016-01-01

    Small amounts of cyclic monomers and oligomers are present in polyamide (PA)-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam) and PA66 (a polymer of 1,6-diaminohexane and adipic acid). Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of m...

  20. Experiments on different materials (polyamide, stainless & galvanized steel) influencing geothermal CaCO3 scaling formation: Polymorphs & elemental incorporation

    Science.gov (United States)

    Wedenig, Michael; Dietzel, Martin; Boch, Ronny; Hippler, Dorothee

    2016-04-01

    Thermal water is increasingly used for heat and electric power production providing base-load capable renewable and virtually unlimited geothermal energy. Compared to other energy sources geothermal facilities are less harmful to the environment, i.e. chemically and visually. In order to promote the economic viability of these systems compared to other traditional and renewable energy sources, production hindering processes such as corrosion and scaling of components arising from the typically high salinity thermal waters have to be considered as important economic factors. In this context, using proper materials being in contact with the thermal water is crucial and a playground for further improvements. Aim of the study presented, are basic experiments and observations of scaling and corrosive effects from hydrothermal water interacting with different materials and surfaces (stainless steel, polyamide, galvanized steel) and in particular the nucleation and growth effects of these materials regarding the precipitation of solid carbonate phases. The incorporation of Mg, Sr and Ba cations into the carbonate scalings are investigated as environmental proxy. For this purpose, hydrothermal carbonate precipitating experiments were initialized by mixing NaHCO3 and Ca-Mg-Sr-Ba-chloride solutions at temperatures ranging from 40 to 80 °C in glass reactors hosting artificial substrates of the above mentioned materials. The experiments show a strong dependence of the precipitation behaviour of calcium carbonate polymorphs on the particular material being present. Stainless steel and polyamide seem to restrict aragonite formation, whereas galvanized steel supports aragonite nucleation. Vaterite formation is promoted by polyamide surfaces. Importantly, vaterite is more soluble (less stable) compared to the other anhydrous calcium carbonate polymorphs, i.e. vaterite can be more easily re-dissolved. Thus, the use of polyamide components might reduce the amount and durability of

  1. Surface modification of polyamide reverse osmosis membrane with organic-inorganic hybrid material for antifouling

    Science.gov (United States)

    Zhang, Yang; Wan, Ying; Pan, Guoyuan; Yan, Hao; Yao, Xuerong; Shi, Hongwei; Tang, Yujing; Wei, Xiangrong; Liu, Yiqun

    2018-03-01

    A series of thin-film composite reverse osmosis membranes based on polyamide have been modified by coating the polyvinyl alcohol and 3-mercaptopropyltriethoxysilane aqueous solution prepared by a sol-gel process on the membrane surface, followed by thermal crosslinking treatment. In order to improve the hydrophilicity of the modified TFC membranes, the membranes were then immersed into H2O2 aqueous solution to convert -SH into -SO3H. The resulting TFC membranes were characterized by SEM, AFM, ATR-FTIR, streaming potential, XPS as well as static contact angle. After surface modification with the organic-inorganic hybrid material, the TFC membranes show increased NaCl rejection and decreased water flux with increasing 3-mercaptopropyltrimethoxysilane content in coating solution. The optimal modification membrane (PA-SMPTES-0.8) exhibits a NaCl rejection of 99.29%, higher than that (97.20%) of the virgin PA membrane, and a comparable water flux to virgin PA membrane (41.7 L/m2 h vs 47.9 L/m2 h). More importantly, PA-SMPTES-0.8 membrane shows much more improved fouling resistance to BSA than virgin PA and PVA modified PA (PA-PVA-1.0) membranes. PA-SMPTES-0.8 membrane loses about 13% of the initial flux after BSA fouling for 12 h, which is lower than that of virgin PA and PA-PVA-1.0 membranes (42% and 18%). Furthermore, the flux recovery of PA-SMPTES-0.8 membrane reaches 94% after cleaning. Thus the TFC membranes modified by this organic-inorganic hybrid technology show potential applications as antifouling RO membrane for desalination and purification.

  2. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    International Nuclear Information System (INIS)

    Shin, Boo Young; Kim, Jae Hong

    2015-01-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity. - Highlights: • PA6 was modified by the electron-beam initiated mediation process. • Maximum increase in complex viscosity of modified PA6 was 75 times higher than virgin PA6 at 0.1 rad/s. • Mechanical properties were improved without scarifying of processability. • The GMA as a mediator played a key role in the electron-beam initiated mediation process

  3. Electrospinning and characterization of polyamide 66 nanofibers with different molecular weights

    Directory of Open Access Journals (Sweden)

    Lilia Muller Guerrini

    2009-06-01

    Full Text Available Polyamide 66 (PA66 nanofibers of different molecular weights were obtained by electrospinning of formic acid solutions. An ionic salt, NaCl, was also added to the solutions to increase the conductivity. PA66 concentrations between 15-17 wt.(%/v and electrical fields between 2.0 and 2.5 kV/cm were the best conditions to produce the smallest nanofibers; however, the addition of NaCl increased the fibers average diameters.The characterization of the fibers was done by scanning electron microscopy (SEM, differential scanning calorimetry (DSC, wide angle X rays diffraction (WAXD and Fourier Transformed Infrared (FTIR. As the molecular weight decreased, the nanofibers average diameters also decreased; however, critical number average and weight average molecular weights were necessary for electrospinning. As the amounts of carboxyl terminal groups (CTG increased, the nanofibers average diameters decreased; however, above CTG's critical values of 8.7 x 10-5 mol.g-1 no electrospinning was possible. The addition of ionic salt increased the electrical conductivity of the solutions and increased the nanofibers' average diameters. By DSC, residual solvent in all the electrospun mats was found; two melting endotherms, one between 248 and 258 °C and the other one between 258 and 267 °C, depending on the sample were also observed. These endotherms were attributed to the melting, re-crystallization and re-melting of the PA66 α-phase. The nanofibers had low % of crystallinity compared to a textile fiber. By WAXS and FTIR, confirmation of the presence of α-phase crystals, of small dimensions and highly imperfect and of a very small amount of β and γ-phases crystals in the nanofibers structure was obtained.

  4. Dual-skinned polyamide/poly(vinylidene fluoride)/cellulose acetate membranes with embedded woven

    KAUST Repository

    Duong, Phuoc H.H.

    2016-08-31

    We propose multilayer membranes including (i) a thin selective polyamide (PA) layer prepared via interfacial polymerization, (ii) a poly (vinylidene fluoride) (PVDF) asymmetric porous support with high adhesion to the PA layer and high mechanical strength, (iii) a strong woven fabric, and (iv) fouling resistant porous cellulose acetate (CA) layer. The PA layer rejects solutes of the draw solution. The PVDF/woven fabric/CA (PVDF/CA) integrated layer performs as a mechanical support with unique properties for forward osmosis (FO) applications. It consists of a modified PVDF top layer suitable for the deposition of a PA layer and a highly hydrophilic bottom layer (CA) with a tunable pore size to minimize foulant deposition and intrusion onto and into the support. The experimental results using bovine serum albumin (BSA) as a model foulant show that the presence of the CA layer at the bottom of the FO membrane (PA/PVDF/CA) reduces 75% fouling propensity compared to the simple FO membrane made of PVDF, woven fabric and PA (PA/PVDF). Fouling tests with 2000 ppm oily feed faced the bottom of the FO membranes further indicate the superiority of the PA/PVDF/CA membrane compared to the PA/PVDF membrane. Moreover, the bottom CA layer can be adjusted with a flexible range of pore size, varied from sub-micron to sub-nanometer depending on the feed composition. The newly developed multilayer FO membrane has comparable performance to the state-of-the-art membrane with added tailored fouling resistance for specific wastewater feeds.

  5. Electromechanical properties of polyamide/lycra fabric treated with PEDOT:PSS

    Science.gov (United States)

    Tadesse, M. G.; Mengistie, D. A.; Loghin, C.; Chen, Y.; Wang, L.; Catalin, D.; Müller, C.; Nierstrasz, V.

    2017-10-01

    One of the challenges in smart textiles is to develop suitable multifunctional materials that can address simultaneously several characteristics such as durability, stretchability, lightweight, and conductivity. Conductive polymers which showed success in different technological fields like polymer solar cells and light emitting diodes are promising in many smart textile applications. In this work, we treated a common polyamide/lycra knitted fabric with PEDOT:PSS for stretchable e-textiles. PEDOT:PSS, with DMSO as a conductivity enhancer and different ratios of water-based polyurethane dispersions as a binder, was applied to the fabric with simple immersion and coating applications. The effect of different application methods and binder ratio on the surface resistance of the fabric was monitored with four point probe electrical surface resistance measurement systems. Samples prepared by immersion technique are more uniform and have higher conductivity than those prepared by a coating technique. SEM images showed that PEDOT:PSS is incorporated into the structure in the immersion method while in the coating it is majorly present on the surface of the fabric. The tensile measurement showed that the acidic PEDOT:PSS and polyurethane dispersion coating has no adverse effect on the tensile strength of the fabric. The coated samples can be stretched up to 700% while still reasonably conductive. The resistance increases only by a small amount when samples were stretched cyclically by stretching 100%. Generally, samples prepared by the immersion method maintained better conductivity while stretching than those by a coating method. The washing fastness of the samples was also assessed.

  6. Development of nanocomposites polyamide66/ bentonite clay membranes obtained by solution for water-oil separation

    International Nuclear Information System (INIS)

    Medeiros, Keila Machado de

    2010-01-01

    Microporous membranes were obtained from nanocomposites polyamide66 and regional bentonite clay, through the technique of immersion precipitation. The nanocomposites were obtained by solution with a pre-established reaction time. The clay was treated with quaternary ammonium salt (Cetremide®) in order to make it organophilic. Untreated and treated clay were characterized by X-ray fluorescence (XRF) spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD) and thermogravimetry (TG), which confirmed the insertion of the Cetremide® salt in the layers of clay and their thermal stability. While the membranes were characterized by XRD, TG, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and flow measurements. The results of XRD, TG and DSC confirmed the thermal stability and morphological structure with intercalated/partially exfoliated lamellae of clay in the polymer matrix. By SEM, it was revealed an asymmetric morphology consisting of a skin layer and a porous sublayer. The higher clay content in the membrane give the lower film thickness. This influencing directly the flow measurements of the membranes produced from the nanocomposites. In general, the initial flow with distilled water through the membranes decrease and stabilise after 60 min, this due to a compression or swelling occurred in the membranes. In tests of water-oil separation it was found that the relationship J/J0 tends to be greater when using emulsions with lower concentration. The water-oil separation tests at concentrations of 300 and 500 ppm for all membranes showed a significant reduction in oil concentration in the permeate, thus showing that these membranes have potential for this application. (author)

  7. Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

    International Nuclear Information System (INIS)

    Kan, Ze; Chen, Peng; Liu, Zhengying; Feng, Jianmin; Yang, Mingbo

    2015-01-01

    Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, and the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects

  8. Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

    Science.gov (United States)

    Kan, Ze; Chen, Peng; Liu, Zhengying; Feng, Jianmin; Yang, Mingbo

    2015-05-01

    Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, and the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects.

  9. Preparation and water desalination properties of POSS-polyamide nanocomposite reverse osmosis membranes

    KAUST Repository

    Duan, Jintang

    2015-01-01

    The application of nanotechnology to thin-film nanocomposites (TFN) is a new route to enhance membrane performance in water desalination. Here, the potential of polyhedral oligomeric silsesquioxane (POSS) as the nanofiller in polyamide (PA) reverse osmosis membranes was systematically investigated. Four POSS materials (P-8Phenyl, P-8NH3Cl, P-8NH2 and P-1NH2) were introduced into the selective layer by physical blending or chemical fixation during standard interfacial polymerization. Water flux and NaCl rejection were measured with 2000ppm NaCl solution under 15.5bar pressure, and SEM and TEM images of membrane selective layers were obtained. Membranes prepared without POSS showed water flux of 20.0±0.5L/m2·h and salt rejection of 98.0±0.2%. TFN membranes prepared with 0.4% (w/v) P-8Phenyl in the organic phase showed a 65% increase in water flux compared to the pristine PA membrane while maintaining high salt rejection. The selective layer of this membrane maintained the typical ridge-and-valley structure of aromatic PA. Results with P-8NH3Cl and P-8NH2 added to the organic phase were similar. TFN membranes prepared with monoamine P-1NH2 in the organic phase had poor water flux of 3.2L/m2·h, a smooth and more hydrophobic surface, and a much thicker (~400nm) selective layer. One of the four POSS compounds studied, P-8NH3Cl, is sufficiently soluble in water for incorporation into the selective layer via the aqueous phase. Membranes were prepared with P-8NH3Cl in the aqueous phase at varying reaction time, loading, and additive (triethylamine) concentration. With these parameters optimized, water flux increased to 35.4L/m2·h.

  10. Influence of Nanomaterial Compatibilization Strategies on Polyamide Nanocomposites Properties and Nanomaterial Release during the Use Phase.

    Science.gov (United States)

    Fernández-Rosas, Elisabet; Vilar, Gemma; Janer, Gemma; González-Gálvez, David; Puntes, Victor; Jamier, Vincent; Aubouy, Laurent; Vázquez-Campos, Socorro

    2016-03-01

    The incorporation of small amounts of nanofillers in polymeric matrices has enabled new applications in several industrial sectors. The nanofiller dispersion can be improved by modifying the nanomaterial (NM) surface or predispersing the NMs to enhance compatibility. This study evaluates the effect of these compatibilization strategies on migration/release of the nanofiller and transformation of polyamide-6 (PA6), a thermoplastic polymer widely used in industry during simulated outdoors use. Two nanocomposites (NCs) containing SiO2 nanoparticles (NPs) with different surface properties and two multiwalled carbon nanotube (MWCNT) NCs obtained by different addition methods were produced and characterized, before and after accelerated wet aging conditions. Octyl-modified SiO2 NPs, though initially more aggregated than uncoated SiO2 NPs, reduced PA6 hydrolysis and, consequently, NM release. Although no clear differences in dispersion were observed between the two types of MWCNT NCs (masterbatch vs direct addition) after manufacture, the use of the MWCNT masterbatch reduced PA6 degradation during aging, preventing MWCNT accumulation on the surface and further release or potential exposure by direct contact. The amounts of NM released were lower for MWCNTs (36 and 108 mg/m(2)) than for SiO2 NPs (167 and 730 mg/m(2)), being lower in those samples where the NC was designed to improve the nanofiller-matrix interaction. Hence, this study shows that optimal compatibilization between NM and matrix can improve NC performance, reducing polymer degradation and exposure and/or release of the nanofiller.

  11. Adsorption of pharmaceuticals onto isolated polyamide active layer of NF/RO membranes.

    Science.gov (United States)

    Liu, Yan-Ling; Wang, Xiao-Mao; Yang, Hong-Wei; Xie, Yuefeng F

    2018-06-01

    Adsorption of trace organic compounds (TrOCs) onto the membrane materials has a great impact on their rejection by nanofiltration (NF) and reverse osmosis (RO) membranes. This study aimed to investigate the difference in adsorption of various pharmaceuticals (PhACs) onto different NF/RO membranes and to demonstrate the necessity of isolating the polyamide (PA) active layer from the polysulfone (PS) support layer for adsorption characterization and quantification. Both the isolated PA layers and the PA+PS layers of NF90 and ESPA1 membranes were used to conduct static adsorption tests. Results showed that apparent differences existed between the PA layer and the PA+PS layer in the adsorption capacity of PhACs as well as the time necessary to reach the adsorption equilibrium. PhACs with different physicochemical properties could be adsorbed to different extents by the isolated PA layer, which was mainly attributed to electrostatic attraction/repulsion and hydrophobic interactions. The PA layer of ESPA1 exhibited apparently higher adsorption capacities for the positively charged PhACs and similar adsorption capacities for the neutral PhACs although it had significantly less total interfacial area (per unit membrane surface area) for adsorption compared to the PA layer of NF90. The higher affinity of the PA layer of ESPA1 for the PhACs could be due to its higher capacity of forming hydrogen bonds with PhACs resulted from the modified chemistry with more -OH groups. This study provides a novel approach to determining the TrOC adsorption onto the active layer of membranes for the ease of investigating adsorption mechanisms. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Researches on increasing compatibility between mixtures of PPS (poly-phenylene sulfide) and polyamide; Recherches en vue de la compatibilisation de melanges de polyamide et de polysulfure de phenylene

    Energy Technology Data Exchange (ETDEWEB)

    Montagne, O.

    1997-01-08

    This work aims to increase the compatibility between PPS (Poly Phenylene Sulfide) and a Polyamide. In order to do so, a bloc co-polymer was synthesised by the coupling of telechelic oligomers of PPS and PA oligomers. These telechelic oligomers of PPS were synthesised in a single step which a synthesis was made possible were the nitrile and secondary amide functions. These oligomers were characterised by various techniques which lead to a rather good precision (difficult to achieve for insolubility reasons). These oligomers were then coupled with the polyamide oligomers. In order to do so, a new reaction was discovered between an aromatic nitrile and a secondary aliphatic amide. It was assessed both on model molecules and on oligomers. An original mechanism is proposed. Once the characterisation of these copolymers was made, various blends of PPS and PA were studied. At last, the incorporation of the block copolymers in the blend obtained by a twin screw extruder, lead to an improvement of the compatibility between the two polymers and in an increase of the resistance to crack propagation. (author) 314 refs.

  13. Analysis of damage processes in short glass fibre reinforced polyamide under mechanical loading by X-ray refractometry, fracture mechanics and fractography; Analyse der Schaedigungsprozesse in einem kurzglasfaserverstaerkten Polyamid unter mechanischer Belastung mittels Roentgenrefraktometrie, Bruchmechanik und Fraktografie

    Energy Technology Data Exchange (ETDEWEB)

    Guenzel, Stephan

    2013-04-01

    This thesis presents an analysis of the damage behaviour in a short glass fibre reinforced polyamide. The micro cracking is investigated by X-ray refraction technique under various, mechanical in-service loadings. In this context, potentials and limits of X-ray refraction analysis for short glass fibre reinforced polyamides are compiled. In particular the influence of fibre orientation and the influence of damage mechanisms are examined according to the X-ray refraction analysis and its interpretation. The method offers a quantitative and phenomenological based characterisation of micro crack damage. For the investigated material micro crack damage emerges as fibre matrix debonding and matrix micro cracking. The state of damage correlates with a nonlinear strain portion in a linear manner and depends on the kind of loading. Absorption of moisture in the material may influence significantly the micro crack damage behaviour. Damage of micro cracking appears preferentially under tension. The macro damage due to propagation of a single crack is characterised in an automated test setup, considering the fibre orientation and content of moisture. Based on the findings an empirical assessment approach is developed. The investigations of the micro and macro damage behaviour are accompanied by fractography, in order to support the model assumptions according to damage and fracture mechanisms.

  14. Surface modifications on toughened, fine-grained, recrystallized tungsten with repetitive ELM-like pulsed plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y., E-mail: ykikuchi@eng.u-hyogo.ac.jp [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Sakuma, I.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M. [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Ueda, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Kurishita, H. [Institute for Materials Research, Tohoku University, Ibaraki 311-1313 (Japan)

    2015-08-15

    Surface modifications of toughened, fine-grained, recrystallized tungsten (TFGR W) materials with 1.1 wt.% TiC and 3.3 wt.% TaC dispersoids due to repetitive ELM-like pulsed (∼0.15 ms) helium plasma irradiation have been investigated by using a magnetized coaxial plasma gun. No surface cracking at the center part of the TFGR W samples exposed to 20 plasma pulses of ∼0.3 MJ m{sup −2} was observed. The suppression of surface crack formation due to the increase of the grain boundary strength by addition of TiC and TaC dispersoids was confirmed in comparison with a pure W material. On the other hand, surface cracks and small pits appeared at the edge part of the TFGR W sample after the pulsed plasma irradiation. Erosion of the TiC and TaC dispersoids due to the pulsed plasma irradiation could cause the small pits on the surface, resulting in the surface crack formation.

  15. Surface modifications on toughened, fine-grained, recrystallized tungsten with repetitive ELM-like pulsed plasma irradiation

    Science.gov (United States)

    Kikuchi, Y.; Sakuma, I.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M.; Ueda, Y.; Kurishita, H.

    2015-08-01

    Surface modifications of toughened, fine-grained, recrystallized tungsten (TFGR W) materials with 1.1 wt.% TiC and 3.3 wt.% TaC dispersoids due to repetitive ELM-like pulsed (∼0.15 ms) helium plasma irradiation have been investigated by using a magnetized coaxial plasma gun. No surface cracking at the center part of the TFGR W samples exposed to 20 plasma pulses of ∼0.3 MJ m-2 was observed. The suppression of surface crack formation due to the increase of the grain boundary strength by addition of TiC and TaC dispersoids was confirmed in comparison with a pure W material. On the other hand, surface cracks and small pits appeared at the edge part of the TFGR W sample after the pulsed plasma irradiation. Erosion of the TiC and TaC dispersoids due to the pulsed plasma irradiation could cause the small pits on the surface, resulting in the surface crack formation.

  16. On the comparison of the ballistic performance of 10% zirconia toughened alumina and 95% alumina ceramic target

    International Nuclear Information System (INIS)

    Zhang, X.F.; Li, Y.C.

    2010-01-01

    Ballistic performance of different type of ceramic materials subjected to high velocity impact was investigated in many theoretical, experimental and numerical studies. In this study, a comparison of ballistic performance of 95% alumina ceramic and 10% zirconia toughened alumina (ZTA) ceramic tiles was analyzed theoretically and experimentally. Spherical cavity model based on the concepts of mechanics of compressible porous media of Galanov was used to analyze the relation of target resistance and static mechanical properties. Experimental studies were carried out on the ballistic performance of above two types of ceramic tiles based on the depth of penetration (DOP) method, when subjected to normal impact of tungsten long rod projectiles. Typical damaged targets were presented. The residual depth of penetration on after-effect target was measured in all experiments, and the ballistic efficiency factor of above two types ceramic plates were determined. Both theoretical and experimental results show that the improvement on ballistic resistance was clearly observed by increasing fracture toughness in ZTA ceramics.

  17. Toughened cyanate ester alloys via reaction-induced phase separation; Hanno yuhatsugataso bunkai ni yoru taishogekisei cyanate ester alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hirohata, T.; Kuroda, M.; Nishimura, A. [Sumitomo Electric Industries, Ltd., Osaka (Japan); Inoue, T. [Tokyo Institute of Technology, Tokyo (Japan)

    1998-03-15

    For the purpose of toughening the matrices of fiber-reinforced plastics (FRPs), the effect of thermosetting/thermoplastic polymer alloys based on cyanate ester alloys is investigated. In the experiment, materials are heated and then allowed to set, which are mixtures of 87.0-43.5wt% of cyanate ester resin, 0-43.5wt% of epoxy resin, and 13.0wt% of soluble polyimide. FRP properties are examined by measuring the after-shock compressive strength, flexural elasticity and flaxural strength, and by performing morphology observation. It is then found that a cyanate ester/soluble polyimide system forms a polymer alloy with phase separation, that its glass transition temperature does not drop, and that the rupture strength is increased approximately twice. A carbon fiber-reinforced plastic (CFRP) incorporating this system is twice higher in after-shock compression strength than a CFRP incorporating a cyanate ester. The system withstands high temperatures, retaining at 200degC approximately 90% of the elastic modulus it exhibits at room temperature. 15 refs., 16 figs.

  18. Strength-toughness relations in sintered and isostatically hot-pressed ZrO2-toughened Al2O3

    International Nuclear Information System (INIS)

    Hori, S.; Yoshimura, M.; Somiya, S.

    1986-01-01

    The fracture toughness of fine-grained undoped ZrO 2 -toughened Al 2 O 3 (ZTA) was essentially unchanged by post-sintering hot isostatic pressing and increased monotonically with ZrO 2 additions up to 25 wt%. The strength of ZTA with 5 to 15 wt% tetragonal ZrO 2 , which depended monotonically on the amount of ZrO 2 present before hot isostatic pressing, was increased by pressing but became almost constant between 5 and 15 wt% ZrO 2 addition. The strength appeared to be controlled by pores before pressing and by surface flaws after pressing; the size of flaws after pressing increased with ZrO 2 content. The strength of ZTA containing mostly monoclinic ZrO 2 (20 to 25 wt%) remained almost constant despite the noticeable density increase upon hot isostatic pressing because the strength was controlled by preexisting microcracks whose extent did not change on postsintering pressing. These strength-toughness relations in sintered and isostatically hot-pressed ZTA are explained on the basis of R-curve behavior. The importance of the contribution of microcracks to the toughness of ZTA is emphasized

  19. Femtosecond laser microstructured Alumina toughened Zirconia: A new strategy to improve osteogenic differentiation of hMSCs

    Science.gov (United States)

    Carvalho, Angela; Cangueiro, Liliana; Oliveira, Vítor; Vilar, Rui; Fernandes, Maria H.; Monteiro, Fernando J.

    2018-03-01

    The use of topographic patterns has been a continuously growing area of research for tissue engineering and it is widely accepted that the surface topography of biomaterials can influence and modulate the initial biological response. Ultrafast lasers are extremely powerful tools to machine and pattern the surface of a wide range of biomaterials, however, only few work has been performed on ceramics with the intent of biomedical applications, and the biological characterization of these structured materials is scarce. In this work, relevance is given to the biological performance of such materials. A femtosecond laser ablation technique was used to modify Alumina toughened Zirconia (ATZ) surface topography, developing surfaces structured at the micro and nanoscale levels (μATZ), in a controlled and reproducible manner. Materials characterization was performed before and after laser treatment, and both materials were compared in terms of osteogenic response of human bone marrow derived mesenchymal stem cells cultured under basal conditions, expecting that the micro/nanofeatures will improve the biological response of cells. Cells metabolic activity and proliferation increased with the culture time and surface microtopography modulated cells alignment and guided proliferation. The modified surface, displayed significantly higher expression of osteogenic transcription factors and genes and, additionally, the formation of a mineralized extracellular matrix, when compared to the control surface, i.e. unmodified ATZ.

  20. Preparative separation of polyphenols from artichoke by polyamide column chromatography and high-speed counter-current chromatography

    International Nuclear Information System (INIS)

    Shu, Xikai; Wang, Mei; Liu, Daicheng; Wang, Daijie; Lin, Xiaojing; Liu, Jianhua; Wang, Xiao; Huang, Luqi

    2013-01-01

    An efficient method for the rapid separation and purification of polyphenols from artichoke by polyamide column chromatography in combination with high-speed counter-current chromatography (HSCCC) was successfully built. The crude ethanol extracts from dry artichoke were first pre-separated by polyamide column chromatography and divided in two parts as sample 1 and sample 2. Then, the samples were further separated by HSCCC and yielded 7.8 mg of chlorogenic acid (compound I), 24.5 mg of luteolin-7-O-β-D-rutinoside (compound II), 18.4 mg of luteolin-7-O-β-D-glucoside (compound III), and 33.4 mg of cynarin (compound IV) with purity levels of 92.0%, 98.2%, 98.5%, and 98.0%, respectively, as determined by high-performance liquid chromatography (HPLC) method. The chemical structures of these compounds were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). (author)

  1. Sequence-specific DNA alkylation targeting for Kras codon 13 mutation by pyrrole-imidazole polyamide seco-CBI conjugates.

    Science.gov (United States)

    Taylor, Rhys Dylan; Asamitsu, Sefan; Takenaka, Tomohiro; Yamamoto, Makoto; Hashiya, Kaori; Kawamoto, Yusuke; Bando, Toshikazu; Nagase, Hiroki; Sugiyama, Hiroshi

    2014-01-27

    Hairpin N-methylpyrrole-N-methylimidazole polyamide seco-CBI conjugates 2-6 were designed for synthesis by Fmoc solid-phase synthesis, and their DNA-alkylating activities against the Kras codon 13 mutation were compared by high-resolution denaturing gel electrophoresis with 225 base pair (bp) DNA fragments. Conjugate 5 had high reactivity towards the Kras codon 13 mutation site, with alkylation occurring at the A of the sequence 5'-ACGTCACCA-3' (site 2), including minor 1 bp-mismatch alkylation against wild type 5'-ACGCCACCA-3' (site 3). Conjugate 6, which differs from conjugate 5 by exchanging one Py unit with a β unit, showed high selectivity but only weakly alkylated the A of 5'-ACGTCACCA-3' (site 2). The hairpin polyamide seco-CBI conjugate 5 thus alkylates according to Dervan's pairing rule with the pairing recognition which β/β pair targets T-A and A-T pairs. SPR and a computer-minimized model suggest that 5 binds to the target sequence with high affinity in a hairpin conformation, allowing for efficient DNA alkylation. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Preparative separation of polyphenols from artichoke by polyamide column chromatography and high-speed counter-current chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Xikai; Wang, Mei; Liu, Daicheng [College of Life Science, Shandong Normal University, Jinan, Shandong (China); Wang, Daijie; Lin, Xiaojing; Liu, Jianhua; Wang, Xiao; Huang, Luqi, E-mail: wxjn1998@126.com [Shandong Analysis and Test Center, Shandong Academy of Sciences, Jinan, Shandong (China)

    2013-09-01

    An efficient method for the rapid separation and purification of polyphenols from artichoke by polyamide column chromatography in combination with high-speed counter-current chromatography (HSCCC) was successfully built. The crude ethanol extracts from dry artichoke were first pre-separated by polyamide column chromatography and divided in two parts as sample 1 and sample 2. Then, the samples were further separated by HSCCC and yielded 7.8 mg of chlorogenic acid (compound I), 24.5 mg of luteolin-7-O-{beta}-D-rutinoside (compound II), 18.4 mg of luteolin-7-O-{beta}-D-glucoside (compound III), and 33.4 mg of cynarin (compound IV) with purity levels of 92.0%, 98.2%, 98.5%, and 98.0%, respectively, as determined by high-performance liquid chromatography (HPLC) method. The chemical structures of these compounds were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). (author)

  3. Characterization of Polyamide 66 membranes prepared by phase inversion using formic acid and hydrochloric acid such as solvents

    Directory of Open Access Journals (Sweden)

    Patrícia Poletto

    2011-12-01

    Full Text Available The membranes properties prepared from water/formic acid (FA/ polyamide 66 (PA66 and water/hydrochloric acid (HCl/polyamide 66 (PA 66 systems has been studied. The different solvents interact distinctly with the polymer, affecting the membrane morphology. The asymmetric structure of the membranes showed a dense top layer and a porous sublayer. The membranes M-HCl prepared from HCl/PA 66 system showed a larger dense layer (around 23 μm in compared to those prepared from FA/PA 66 system (M-FA (around 10 μm. The membrane morphology was a determinant factor in results of water absorption, porosity and pure water flux. The lower thickness of dense layer in M-FA membranes resulted in a higher water absorption and, consequently, porosity, approximately 50%, compared with M-HCl membranes, approximately 15%. The same trend was observed to permeate flux, the lower thickness of dense layer higher pure water flux.

  4. Effects of surface coating process conditions on the water permeation and salt rejection properties of composite polyamide reverse osmosis membranes

    KAUST Repository

    Louie, Jennifer Sarah

    2011-02-01

    The application of polymer surface coatings to improve the fouling resistance of reverse osmosis membranes tends to increase flow resistance across the membrane. This paper presents a systematic analysis on how membrane properties and performance are impacted by the coating process steps, and investigates how such effects could contribute to lower water flux. On one hand, simply pre-soaking dry aromatic polyamide composite membranes in aliphatic alcohols results in a significant increase in water flux, which is attributed to wetting of pores in the selective polyamide layer and to changes in the polymer structure. This flux increase was not readily reversible, based on a 300-h water permeation test. Conversely, drying a wetted membrane led to a decrease in water flux, which we hypothesize is caused by increased interchain hydrogen-bonding in the selective layer. This drop in water flux was not permanent; higher flux was observed if the same wetted/dried membrane was then re-soaked in ethanol prior to the water permeation experiment. An ethanol pre-soaking step also increased water flux of a PEBAX-coated membrane by nearly 70%. In contrast to the reduction in water flux caused by the specific treatment sequence of ethanol-swelling followed by drying, this same sequence actually increased gas transport. The eight- to ten-fold increase in Knudsen diffusion-based gas permeance after this pre-treatment was attributed to an increase in the number or size of membrane defects. © 2010 Elsevier B.V.

  5. Evaluation of Ultimate Pressure Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Choun, Youngsun; Hahm, Daegi [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Fiber reinforced concrete (FRC) includes thousands of small fibers that are distributed randomly in the concrete. Fibers resist the growth of cracks in concrete through their bridging at the cracks. Therefore, FRC fails in tension only when the fibers break or are pulled out of the cement matrix. For this reason, the addition of fibers in concrete mixing increases the tensile toughness of concrete and enhances the post-cracking behavior. A prevention of through-wall cracks and an increase of the post-cracking ductility will improve the ultimate internal pressure capacity of a prestressed concrete containment building (PCCB). In this study, the effects of steel or polyamide fiber reinforcement on the ultimate pressure capacity of a PCCB are evaluated. When R-SFRC contains hooked steel fibers in a volume fraction of 1.0%, the ultimate pressure capacity of a PCCB can be improved by 17%. When R-PFRC contains polyamide fibers in a volume fraction of 1.5%, the ultimate pressure capacity of a PCCB can be enhanced by 10%. Further studies are needed to determine the strain limits acceptable for PCCBs reinforced with fibers.

  6. Evaluation of Ultimate Pressure Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

    International Nuclear Information System (INIS)

    Choun, Youngsun; Hahm, Daegi

    2014-01-01

    Fiber reinforced concrete (FRC) includes thousands of small fibers that are distributed randomly in the concrete. Fibers resist the growth of cracks in concrete through their bridging at the cracks. Therefore, FRC fails in tension only when the fibers break or are pulled out of the cement matrix. For this reason, the addition of fibers in concrete mixing increases the tensile toughness of concrete and enhances the post-cracking behavior. A prevention of through-wall cracks and an increase of the post-cracking ductility will improve the ultimate internal pressure capacity of a prestressed concrete containment building (PCCB). In this study, the effects of steel or polyamide fiber reinforcement on the ultimate pressure capacity of a PCCB are evaluated. When R-SFRC contains hooked steel fibers in a volume fraction of 1.0%, the ultimate pressure capacity of a PCCB can be improved by 17%. When R-PFRC contains polyamide fibers in a volume fraction of 1.5%, the ultimate pressure capacity of a PCCB can be enhanced by 10%. Further studies are needed to determine the strain limits acceptable for PCCBs reinforced with fibers

  7. Preparation of epoxy-functionalized methyl methacrylate-butadiene-styrene core-shell particles and investigation of their dispersion in polyamide-6

    NARCIS (Netherlands)

    Aerdts, A.M.; Groeninckx, G.; Zirkzee, H.F.; Aert, van H.A.M.; Geurts, J.M.

    1997-01-01

    Functional core—shell impact modifiers of glycidyl methacrylate (GMA) functionalized methyl methacrylate—butadiene—styrene (MBS) have been prepared via a seeded semi-continuous emulsion polymerization. These functional MBS—GMA particles were blended with polyamide-6. Investigations by transmission

  8. 3D morphological characterization of the polyamide active layer of RO and NF membranes using TEM and soft X-ray scattering

    Science.gov (United States)

    Culp, Tyler; Paul, Mou; Roy, Abhishek; Rosenberg, Steve; Behr, Michael; Kumar, Manish; Gomez, Enrique; Penn State Team; Dow Team

    Polyamide-based thin-film composite (TFC) membranes used for reverse osmosis (RO) and nanofiltration (NF) separation processes are at the forefront of water desalination and purification technologies due to their high salt rejection, high energy efficiency, and ease of operation. Nevertheless, in spite of the benefits of RO and NF membranes, many open questions about the internal nanostructure of the membrane active layer remain, such as the dispersion and distribution of acid functional groups. We demonstrate that resonant soft X-ray scattering (RSOXS), where the X-ray energy is tuned to absorption edges of the constituent materials, is a powerful tool to examine the microstructure of the polyamide layer. In conjunction with complementary techniques such as transmission electron microscopy (TEM), where tomography is used to obtain a 3D reconstruction of the polyamide active layer, the effect of cross-linking can be quantified in 3D for a systematic series of membranes. This relationship can then be applied to a series of commercially available RO and NF membranes where the effect of polyamide cross-linking on their respective structure and water transport properties can be evaluated. The combination of RSOXS with traditional characterization tools provides a strategy for linking the chemical structure to the morphology and water transport properties of RO and NF membranes.

  9. Synthesis and characterization of soluble, blue-fluorescent polyamides and polyimides containing substituted p-terphenyl as well as long aliphatic segments in the main chain

    NARCIS (Netherlands)

    Mikroyannidis, JA; Tsivgoulis, GM

    1999-01-01

    A novel class of semiflexible polyamides and polyimides bearing substituted p-terphenyl as well as long aliphatic segments in the main chain were synthesized through pyrylium salts. Characterization of polymers was accomplished by inherent viscosity, elemental analysis, FT-IR, NMR, UV-vis

  10. Influence of properties and morphology of elastomeric phase on the behavior of ternary reactive blends of polyamide 6/rigid polymer/elastomer

    Czech Academy of Sciences Publication Activity Database

    Kelnar, Ivan; Kotek, Jiří; Munteanu, B. S.; Fortelný, Ivan

    2003-01-01

    Roč. 89, č. 13 (2003), s. 3647-3651 ISSN 0021-8995 R&D Projects: GA ČR GA106/01/0601 Institutional research plan: CEZ:AV0Z4050913 Keywords : polyamides * toughness * elastomers Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.017, year: 2003

  11. Highly toughened polypropylene/ethylene–propylene-diene monomer/zinc dimethacrylate ternary blends prepared via peroxide-induced dynamic vulcanization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yukun, E-mail: cyk@scut.edu.cn [The Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Xu, Chuanhui [College of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Cao, Liming [The Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Cao, Xiaodong [College of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2013-02-15

    Polypropylene (PP)/ethylene–propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blends with remarkable toughness and extensibility were successfully prepared via peroxide dynamical vulcanization. A unique structure with the EPDM particles surrounded by a transition zone containing numerous polymerized ZDMA (PZDMA) nano-particles was observed for the first time by using transmission electron microscopy (TEM) examination, which contributed to the dramatically increase of Izod impact strength. Dynamic mechanical analysis (DMA) confirmed that the possible PZDMA graft products resulted from peroxide dynamical vulcanization improved the compatibility between EPDM and PP phases. The specific morphology of the PP/EPDM/ZDMA blends indicated that ZDMA can lead to size reduction and good distribution uniformity of the crosslinked rubber particles and the increase of adhesion between PP matrix and EPDM phases during deformation. The synergic effect of the increase in the effective volume of the EPDM phase, the improved compatibility and adhesion between EPDM and PP phases and the deformation of those fine rubber particles is believed to result in the remarkable high toughness and extensibility of the PP/EPDM/ZDMA blends. Particularly for the PP/EPDM ratio of 70/30, the PP/EPDM/ZDMA (70/30/9, w/w/w) ternary blends with the Izod impact strength nearly 2 times higher than PP/EPDM (70/30, w/w) binary blends and 15–20 times higher than PP are achieved; besides, the elongation at break of PP/EPDM/ZDMA ternary blends is 4–5 times higher than that of PP/EPDM binary blends. - Highlights: ► ZDMA largely toughen peroxide dynamically vulcanized PP/EPDM blend. ► PZDMA graft products improved the compatibility and adhesion between EPDM and PP. ► Size reduction and good distribution uniformity of crosslinked rubber particles.

  12. Highly toughened polypropylene/ethylene–propylene-diene monomer/zinc dimethacrylate ternary blends prepared via peroxide-induced dynamic vulcanization

    International Nuclear Information System (INIS)

    Chen, Yukun; Xu, Chuanhui; Cao, Liming; Cao, Xiaodong

    2013-01-01

    Polypropylene (PP)/ethylene–propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blends with remarkable toughness and extensibility were successfully prepared via peroxide dynamical vulcanization. A unique structure with the EPDM particles surrounded by a transition zone containing numerous polymerized ZDMA (PZDMA) nano-particles was observed for the first time by using transmission electron microscopy (TEM) examination, which contributed to the dramatically increase of Izod impact strength. Dynamic mechanical analysis (DMA) confirmed that the possible PZDMA graft products resulted from peroxide dynamical vulcanization improved the compatibility between EPDM and PP phases. The specific morphology of the PP/EPDM/ZDMA blends indicated that ZDMA can lead to size reduction and good distribution uniformity of the crosslinked rubber particles and the increase of adhesion between PP matrix and EPDM phases during deformation. The synergic effect of the increase in the effective volume of the EPDM phase, the improved compatibility and adhesion between EPDM and PP phases and the deformation of those fine rubber particles is believed to result in the remarkable high toughness and extensibility of the PP/EPDM/ZDMA blends. Particularly for the PP/EPDM ratio of 70/30, the PP/EPDM/ZDMA (70/30/9, w/w/w) ternary blends with the Izod impact strength nearly 2 times higher than PP/EPDM (70/30, w/w) binary blends and 15–20 times higher than PP are achieved; besides, the elongation at break of PP/EPDM/ZDMA ternary blends is 4–5 times higher than that of PP/EPDM binary blends. - Highlights: ► ZDMA largely toughen peroxide dynamically vulcanized PP/EPDM blend. ► PZDMA graft products improved the compatibility and adhesion between EPDM and PP. ► Size reduction and good distribution uniformity of crosslinked rubber particles

  13. Influence of the clay content and drying of successive no solvents change in the morphology of polyamide 6 / clay membranes

    International Nuclear Information System (INIS)

    Pereira, C.H.; Ferreira, R.S.B.; Bezerra, E.B.; Leite, A.M.D.; Araujo, E.D.; Lira, H.L.

    2014-01-01

    Membranes of polyamide 6/clay nanocomposites with different contents (1 and 3%) of Brazilian bentonite clay using the technique of phase inversion was obtained. The nanocomposites were obtained in a co-rotating twin screw extruder, by the melt intercalation method and were characterized by x-ray diffraction (XRD), which showed possibly an exfoliated and / or partially exfoliated structure was obtained. The membranes were dried at room temperature and also by successive exchange of non-solvents, to prevent collapse the pores using ethanol and n-hexane as a non-solvent. From the photomicrographs of top surface by scanning electron microscopy (SEM) showed to morphology change in the membranes from the presence of different clay contents as well as drying the same by successive exchange of non-solvents, obtaining membranes with larger amount of pores uniformly distributed. (author)

  14. High-performance multi-functional reverse osmosis membranes obtained by carbon nanotube·polyamide nanocomposite

    Science.gov (United States)

    Inukai, Shigeki; Cruz-Silva, Rodolfo; Ortiz-Medina, Josue; Morelos-Gomez, Aaron; Takeuchi, Kenji; Hayashi, Takuya; Tanioka, Akihiko; Araki, Takumi; Tejima, Syogo; Noguchi, Toru; Terrones, Mauricio; Endo, Morinobu

    2015-01-01

    Clean water obtained by desalinating sea water or by purifying wastewater, constitutes a major technological objective in the so-called water century. In this work, a high-performance reverse osmosis (RO) composite thin membrane using multi-walled carbon nanotubes (MWCNT) and aromatic polyamide (PA), was successfully prepared by interfacial polymerization. The effect of MWCNT on the chlorine resistance, antifouling and desalination performances of the nanocomposite membranes were studied. We found that a suitable amount of MWCNT in PA, 15.5 wt.%, not only improves the membrane performance in terms of flow and antifouling, but also inhibits the chlorine degradation on these membranes. Therefore, the present results clearly establish a solid foundation towards more efficient large-scale water desalination and other water treatment processes. PMID:26333385

  15. Photo and Thermal Behavior of New Reinforced Polyamide-nanocomposite Montmorillonite on 2,3-Pyrazin Dicarboxylic Acid

    Science.gov (United States)

    Faghihi, Khalil; Samiei, Mojtaba; Hajibeygi, Mohsen

    2012-06-01

    Two new samples of reinforce polyamidemontmorillonite nanocomposites were synthesized by a convenient solution intercalation technique. Polyamide (PA) 3 as a source of polymer matrix was synthesized by the direct polycondensation reaction of pyrazine 2,3-dicarboxylic acid 1 with 4,4'-diamino diphenyl ether 2 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PA matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

  16. Direct assembly of in situ templated CdSe quantum dots via crystalline lamellae structure of polyamide 66

    Energy Technology Data Exchange (ETDEWEB)

    Cheval, Nicolas; Brooks, Richard [University of Nottingham, Division of Materials, Mechanics and Structures, Faculty of Engineering (United Kingdom); Fahmi, Amir, E-mail: Amir.Fahmi@hochschule-Rhein-waal.de [Rhein-Waal University of Applied Sciences, Faculty of Technology and Bionics (Germany)

    2012-03-15

    A simple concept is proposed for templating in situ synthesised CdSe quantum dots (QDs) into an organised nano-pattern using the crystalline lamellae structure of polyamide 66 (PA66). The morphology obtained for PA66 and the hybrid material on Si/SiO{sub x} solid substrate was characterised by means of atomic force microscope. Controlling the PA66 concentration in solution and the organic-inorganic interactions are found to be the keys factors to direct the assembly of CdSe QDs along the PA66 linear crystalline structure. This simple approach could be opened a new avenue for a large spectrum of innovative high-tech applications.

  17. Direct investigations of deformation and yield induced structure transitions in polyamide 6 below glass transition temperature with WAXS and SAXS

    DEFF Research Database (Denmark)

    Guo, Huilong; Wang, Jiayi; Zhou, Chengbo

    2015-01-01

    Deformation and yield induced structure transitions of polyamide 6 (PA6) were detected with the combination of the wide- and small-angle X-ray scattering (WAXS and SAXS) at 30 degrees C below glass transition temperature (T-g) of PA6. During deformation, gamma-alpha phase transition was found...... at elastic stage. The concentrated stress in crystals at elastic stage provided adequate energy for the direct gamma-alpha phase transition under T-g. The force to promote the gamma-phase into a phase directly is insufficient at the yield stage and a transient phase as a compromise was formed. The transient...... phase was confirmed by DSC measurements and assisted the gamma-alpha phase transition indirectly. The gamma-phase slips into incomplete fragments at yield point, and the parts along tensile direction are responsible for the formation of transient phase. The gamma-fragments after yield is oriented...

  18. Recognition by nonaromatic and stereochemical subunit-containing polyamides of the four Watson-Crick base pairs in the DNA minor groove.

    Science.gov (United States)

    Zhang, Hong-Fei; Wu, Yan-Ling; Jiang, Shi-Kun; Wang, Pu; Sugiyama, Hiroshi; Chen, Xing-Lai; Zhang, Wen; Ji, Yan-Juan; Guo, Chuan-Xin

    2012-06-18

    In order to develop an optimal subunit as a T-recognition element in hairpin polyamides, 15 novel chirality-modified polyamides containing (R)-α,β-diaminopropionic acid ((R) β α-NH 2), (S)-α,β-diaminopropionic acid ((S) β α-NH 2), (1R,3S)-3-aminocyclopentanecarboxylic acid ((RS) Cp), (1S,3R)-3-amino-cyclopentanecarboxylic acid ((RS) Cp), (1R,3R)-3-aminocyclopentanecarboxylic acid ((RR) Cp) and (1S,3S)-3-amino-cyclopentanecarboxylic acid ((SS) Cp) residues were synthesized. Their binding characteristics to DNA sequences 5'-TGCNCAT-3'/3'-ACGN'GTA-5' (N⋅N'=A⋅T, T⋅A, G⋅C and C⋅G) were systemically studied by surface plasmon resonance (SPR) and molecular simulation (MSim) techniques. SPR showed that polyamide 4, AcIm-(S) β α-NH 2-ImPy-γ-ImPy-β-Py-βDp (β/(S) β α-NH 2 pair), bound to a DNA sequence containing a core binding site of 5'-TGCACAT-3' with a dissociation equilibrium constant (K(D) ) of 4.5×10(-8)  m. This was a tenfold improvement in specificity over 5'-TGCTCAT-3' (K(D) =4.5×10(-7)  M). MSim studies supported the SPR results. More importantly, for the first time, we found that chiral 3-aminocyclopentanecarboxylic acids in polyamides can be employed as base readers with only a small decrease in binding affinity to DNA. In particular, SPR showed that polyamide 9 ((RR) Cp/β pair) had a 15-fold binding preference for 5'-TGCTCAT-3' over 5'-TGCACAT-3'. A large difference in standard free energy change for A⋅T over T⋅A was determined (ΔΔG(o) =5.9 kJ mol(-1) ), as was a twofold decrease in interaction energy by MSim. Moreover, a 1:1 stoichiometry (9 to 5'-TGCTCAT-3'/3'-ACGAGTA-5') was shown by MSim to be optimal for the chiral five-membered cycle to fit the minor groove. Collectively, the study suggests that the (S)-α-amino-β-aminopropionic acid and (1R,3R)-3-aminocyclopentanecarboxylic acid can serve as a T-recognition element, and the stereochemistry and the nature of these subunits significantly influence

  19. SiC Nanoparticles Toughened-SiC/MoSi2-SiC Multilayer Functionally Graded Oxidation Protective Coating for Carbon Materials at High Temperatures

    Science.gov (United States)

    Abdollahi, Alireza; Ehsani, Naser; Valefi, Zia; Khalifesoltani, Ali

    2017-05-01

    A SiC nanoparticle toughened-SiC/MoSi2-SiC functionally graded oxidation protective coating on graphite was prepared by reactive melt infiltration (RMI) at 1773 and 1873 K under argon atmosphere. The phase composition and anti-oxidation behavior of the coatings were investigated. The results show that the coating was composed of MoSi2, α-SiC and β-SiC. By the variations of Gibbs free energy (calculated by HSC Chemistry 6.0 software), it could be suggested that the SiC coating formed at low temperatures by solution-reprecipitation mechanism and at high temperatures by gas-phase reactions and solution-reprecipitation mechanisms simultaneously. SiC nanoparticles could improve the oxidation resistance of SiC/MoSi2-SiC multiphase coating. Addition of SiC nanoparticles increases toughness of the coating and prevents spreading of the oxygen diffusion channels in the coating during the oxidation test. The mass loss and oxidation rate of the SiC nanoparticle toughened-SiC/MoSi2-SiC-coated sample after 10-h oxidation at 1773 K were only 1.76% and 0.32 × 10-2 g/cm3/h, respectively.

  20. Supertoughened Biobased Poly(lactic acid)-Epoxidized Natural Rubber Thermoplastic Vulcanizates: Fabrication, Co-continuous Phase Structure, Interfacial in Situ Compatibilization, and Toughening Mechanism.

    Science.gov (United States)

    Wang, Youhong; Chen, Kunling; Xu, Chuanhui; Chen, Yukun

    2015-09-10

    In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel "sea-sea" co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical "sea-island" morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle-ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m(2), nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the effects of various DCP contents on the impact property were investigated. The toughening mechanism under impact testing was researched, and the influence factors for toughening were discussed.

  1. Optical and Thermal Behaviors of Polyamide-Layered Silicate Nanocomposites Based on 4,4'-Azodibenzoic Acid by Solution Intercalation Technique

    Science.gov (United States)

    Faghihi, Khalil; Shabanian, Meisam

    2011-04-01

    Two new samples of polyamide-montmorillonite reinforced nanocomposites based on 4,4'-azodibenzoic acid were prepared by a convenient solution intercalation technique. Polyamide (PA) 4 as a source of polymer matrix was synthesized by the direct polycondensation reaction of 4,4'-azodibenzoic acid 2 with 4,4'-diamino diphenyl sulfone 3 in the presence of triphenyl phosphate (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PA-nanocomposite films 4a and 4b with 10 and 20% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposite films were investigated by using Uv-vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements.

  2. Isolation and identification of arctiin and arctigenin in leaves of burdock (Arctium lappa L.) by polyamide column chromatography in combination with HPLC-ESI/MS.

    Science.gov (United States)

    Liu, Shiming; Chen, Kaoshan; Schliemann, Willibald; Strack, Dieter

    2005-01-01

    A simple method involving polyamide column chromatography in combination with HPLC-PAD and HPLC-ESI/MS for isolating and identifying two kinds of lignans, arctiin and arctigenin, in the leaves of burdock (Arctium lappa L.) has been established. After extraction of burdock leaves with 80% methanol, the aqueous phase of crude extracts was partitioned between water and chloroform and the aqueous phase was fractionated on a polyamide glass column. The fraction, eluting with 100% methanol, was concentrated and gave a white precipitate at 4 degrees C from which two main compounds were purified by semi-preparative HPLC. In comparison with the UV and ESI-MS spectra and the HPLC retention time of authentic standards, the compounds were determined to be arctiin and arctigenin. The extraction/separation technique was validated using an internal standard method.

  3. Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites; Avaliacao da resistencia mecanica sob impacto de nanocompositos de poliamida 6/argila bentonitica

    Energy Technology Data Exchange (ETDEWEB)

    Paz, Rene A.; Leite, Amanda M.D.; Medeirosa, Vanessa da N., E-mail: rene@cct.ufcg.edu.b [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Curso de Pos-Graduacao em Ciencia e Engenharia de Materiais; Araujo, Edcleide M.; Melo, Tomas J.A. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais; Pessan, Luiz A. [Universidade Federal de Sao Carlos (DEMa/UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    Nanocomposites of polymer/clay have had much attention in recent years, particularly those developed with layered silicates due to the need of engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in crystalline structure of polymer matrices has been studied and has been observed that they affect the crystalline behavior and the physical and mechanical properties. In this study, nanocomposites of polyamide 6 were obtained by the melt intercalation method, using a regional bentonite modified with a quaternary ammonium salt in an amount of 3% by weight. XRD results showed that incorporation of salt among the layers of clay, making it organophilic and obtaining exfoliated and/or partially exfoliated structures. The impact properties of the nanocomposites showed inferior in relation to pure polyamide, in other words, lost of toughness. (author)

  4. Study of the radiation effect on the mechanical properties of flammability and the glow wire of polyamide 6.6 with and without fiber glass reinforcement

    International Nuclear Information System (INIS)

    Ferro, Waldir Pedro; Silva, Leonardo Gondim de Andrade e

    2002-01-01

    The Automotive, Electric and Electronic Component Industry, more and more employ the Engineering Plastic as a viable alternative for the reduction of costs and increase of productivity without loss of quality. Polyamide 6.6 is an Engineering Plastic with distinguished role on this category of polymers due to its high thermal and chemical resistances and strength. The aim of this work is to present the results of Tensile Strength, Flexural Strength and Izod Notched Impact Strength as well as thermal experiments of Flammability (Automotive and Electronic Components Industry) and of Glow Wire (Electric Components Industry) of Polyamide 6.6 with or without Fiber Glass reinforcement, irradiated by Electron Beams in different doses. (author)

  5. A New Flame-Retardant Polyamide Containing Phosphine Oxide and N,N-(4,4-diphenylether) Moieties in the Main Chain: Synthesis and Characterization

    OpenAIRE

    FAGHIHI, Khalil

    2014-01-01

    A new flame-retardant polyamide containing phosphine oxide moieties in the main chain was synthesized from the solution polycondensation reaction of bis(3-aminophenyl) phenyl phosphine oxide with N,N-(4,4-diphenylether) bis trimellitimide, using thionyl chloride, N-methyl-2-pyrolidone, and pyridine as condensing agents. This new polymer was obtained in high yield (92%), has high inherent viscosity (0.73 dL/g), and was characterized by elemental analysis, FT-IR spectroscopy, thermal gr...

  6. Modification of PSf/SPSf Blended Porous Support for Improving the Reverse Osmosis Performance of Aromatic Polyamide Thin Film Composite Membranes

    Directory of Open Access Journals (Sweden)

    Li-Fen Liu

    2018-06-01

    Full Text Available In this study, modification of polysulfone (PSf/sulfonated polysulfone (SPSf blended porous ultrafiltration (UF support membranes was proposed to improve the reverse osmosis (RO performance of aromatic polyamide thin film composite (TFC membranes. The synergistic effects of solvent, polymer concentration, and SPSf doping content in the casting solution were investigated systematically on the properties of both porous supports and RO membranes. SEM and AFM were combined to characterize the physical properties of the membranes, including surface pore natures (porosity, mean pore radius, surface morphology, and section structure. A contact angle meter was used to analyze the membrane surface hydrophilicity. Permeate experiments were carried out to evaluate the separation performances of the membranes. The results showed that the PSf/SPSf blended porous support modified with 6 wt % SPSf in the presence of DMF and 14 wt % PSf had higher porosity, bigger pore diameter, and a rougher and more hydrophilic surface, which was more beneficial for fabrication of a polyamide TFC membrane with favorable reverse osmosis performance. This modified PSf/SPSf support endowed the RO membrane with a more hydrophilic surface, higher water flux (about 1.2 times, as well as a slight increase in salt rejection than the nascent PSf support. In a word, this work provides a new facile method to improve the separation performance of polyamide TFC RO membranes via the modification of conventional PSf porous support with SPSf.

  7. Polyamide nanocapsules and nano-emulsions containing Parsol® MCX and Parsol® 1789: in vitro release, ex vivo skin penetration and photo-stability studies.

    Science.gov (United States)

    Hanno, Ibrahim; Anselmi, Cecilia; Bouchemal, Kawthar

    2012-02-01

    To prepare polyamide nanocapsules for skin photo-protection, encapsulating α-tocopherol, Parsol®MCX (ethylhexyl methoxycinnamate) and/or Parsol®1789 (butyl methoxydibenzoylmethane). Nanocapsules were obtained by combining spontaneous emulsification and interfacial polycondensation reaction between sebacoyl chloride and diethylenetriamine. Nano-emulsions used as control were obtained by the same process without monomers. The influence of carrier on release rate was studied in vitro with a membrane-free model. Epidermal penetration of encapsulated sunscreens was ex vivo evaluated using Franz diffusion cells. Ability of encapsulated sunscreens to improve photo-stability was verified by comparing percentage of degradation after UV radiation exposure. Sunscreen-containing nanocapsules (260-400 nm) were successfully prepared; yield of encapsulation was >98%. Parsol®MCX and Parsol®1789 encapsulation led to decreased release rate by up to 60% in comparison with nano-emulsion and allowed minimum penetration through pig ear epidermis. Presence of polyamide shell protected encapsulated sunscreen filters from photo-degradation without affecting their activity. Encapsulation of Parsol®MCX and Parsol®1789 into oil-core of polyamide nanocapsules allowed protection from photo-degradation, controlled release from nanocapsules, and limited penetration through pig ear epidermis.

  8. Missing facial parts computed by a morphable model and transferred directly to a polyamide laser-sintered prosthesis: an innovation study.

    Science.gov (United States)

    Mueller, A A; Paysan, P; Schumacher, R; Zeilhofer, H-F; Berg-Boerner, B-I; Maurer, J; Vetter, T; Schkommodau, E; Juergens, P; Schwenzer-Zimmerer, K

    2011-12-01

    Mirroring of missing facial parts and rapid prototyping of templates have become widely used in the manufacture of prostheses. However, mirroring is not applicable for central facial defects, and the manufacture of a template still requires labour-intensive transformation into the final facial prosthesis. We have explored innovative techniques to meet these remaining challenges. We used a morphable model of a face for the reconstruction of missing facial parts that did not have mirror images, and skin-coloured polyamide laser sintering for direct manufacture of the prosthesis. From the knowledge gleaned from a data set of 200 coloured, three-dimensional scans, we generated a missing nose that was statistically compatible with the remaining parts of the patient's face. The planned prosthesis was manufactured directly from biocompatible skin-coloured polyamide powder by selective laser sintering, and the prosthesis planning system produced a normal-looking reconstruction. The polyamide will need adjustable colouring, and we must be able to combine it with a self-curing resin to fulfil the requirements of realistic permanent use. Copyright © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  9. Novel Organic Phototransistor-Based Nonvolatile Memory Integrated with UV-Sensing/Green-Emissive Aggregation Enhanced Emission (AEE)-Active Aromatic Polyamide Electret Layer.

    Science.gov (United States)

    Cheng, Shun-Wen; Han, Ting; Huang, Teng-Yung; Chang Chien, Yu-Hsin; Liu, Cheng-Liang; Tang, Ben Zhong; Liou, Guey-Sheng

    2018-05-30

    A novel aggregation enhanced emission (AEE)-active polyamide TPA-CN-TPE with a high photoluminesence characteristic was successfully synthesized by the direct polymerization of 4-cyanotriphenyl diamine (TPA-CN) and tetraphenylethene (TPE)-containing dicarboxylic acid. The obtained luminescent polyamide plays a significant role as the polymer electret layer in organic field-effect transistors (OFETs)-type memory. The strong green emission of TPA-CN-TPE under ultraviolet (UV) irradiation can be directly absorbed by the pentacene channel, displaying a light-induced programming and voltage-driven erasing organic phototransistor-based nonvolatile memory. Memory window can be effectively manipulated between the programming and erasing states by applying UV light illumination and electrical field, respectively. The photoinduced memory behavior can be maintained for over 10 4 s between these two states with an on/off ratio of 10 4 , and the memory switching can be steadily operated for many cycles. With high photoresponsivity ( R) and photosensitivity ( S), this organic phototransistor integrated with AEE-active polyamide electret layer could serve as an excellent candidate for UV photodetectors in optical applications. For comparison, an AEE-inactive aromatic polyimide TPA-PIS electret with much weaker solid-state emission was also applied in the same OFETs device architecture, but this device did not show any UV-sensitive and UV-induced memory characteristics, which further confirmed the significance of the light-emitting capability of the electret layer.

  10. Polyethyleneimine-Functionalized Polyamide Imide (Torlon) Hollow-Fiber Sorbents for Post-Combustion CO 2 Capture

    KAUST Repository

    Li, Fuyue Stephanie

    2013-05-24

    Carbon dioxide emitted from existing coal-fired power plants is a major environmental concern due to possible links to global climate change. In this study, we expand upon previous work focused on aminosilane-functionalized polymeric hollow-fiber sorbents by introducing a new class of polyethyleneimine (PEI)-functionalized polymeric hollow-fiber sorbents for post-combustion carbon dioxide capture. Different molecular weight PEIs (Mn≈600, 1800, 10 000, and 60 000) were studied as functional groups on polyamide imide (PAI, Torlon) hollow fibers. This imide ring-opening modification introduces two amide functional groups and was confirmed by FTIR attenuated total reflectance spectroscopy. The carbon dioxide equilibrium sorption capacities of PEI-functionalized Torlon materials were characterized by using both pressure decay and gravimetric sorption methods. For equivalent PEI concentrations, PAI functionalized with lower molecular weight PEI exhibited higher carbon dioxide capacities. The effect of water in the ring-opening reaction was also studied. Up to a critical value, water in the reaction mixture enhanced the degree of functionalization of PEI to Torlon and resulted in higher carbon dioxide uptake within the functionalized material. Above the critical value, roughly 15 % w/w water, the fiber morphology was lost and the fiber was soluble in the solvent. PEI-functionalized (Mn≈600) PAI under optimal reaction conditions was observed to have the highest CO2 uptake: 4.9 g CO2 per 100 g of polymer (1.1 mmol g-1) at 0.1 bar and 35°C with dry 10 % CO2/90 % N2 feed for thermogravimetric analysis. By using water-saturated feeds (10 % CO2/90 % N2 dry basis), CO2 sorption was observed to increase to 6.0 g CO2 per 100 g of sorbent (1.4 mmol g-1). This material also demonstrated stability in cyclic adsorption-desorption operations, even under wet conditions at which some highly effective sorbents tend to lose performance. Thus, PEI-functionalized PAI fibers can be

  11. Fabrication of SiC Composites with Synergistic Toughening of Carbon Whisker and In Situ 3C-SiC Nanowire

    Directory of Open Access Journals (Sweden)

    Zhang Yunlong

    2016-01-01

    Full Text Available The SiC composites with synergistic toughening of carbon whisker and in situ 3C-SiC nanowire have been fabricated by hot press sinter technology and annealed treatment technology. Effect of annealed time on the morphology of SiC nanowires and mechanical properties of the Cw/SiC composites was surveyed in detail. The appropriate annealed time improved mechanical properties of the Cw/SiC composites. The synergistic effect of carbon whisker and SiC nanowire can improve the fracture toughness for Cw/SiC composites. The vapor-liquid-solid growth (VLS mechanism was proposed. TEM photo showed that 3C-SiC nanowire can be obtained with preferential growth plane ({111}, which corresponded to interplanar spacing about 0.25 nm.

  12. Toughening of thermosetting polyimides

    Science.gov (United States)

    Gollob, D. S.; Mandell, J. F.; Mcgarry, F. J.

    1979-01-01

    Work directed toward increasing the resistance to crack propagation of thermoset polyimides is described. Rubber modification and Teflon microfiber impregnation techniques for increasing fracture toughness are investigated. Unmodified Kerimid 601 has a fracture surface work value of 0.20 in-lbs/sq in. Dispersed particles of amine terminated butadiene acrylonitrile liquid rubber or of silicone rubber do not raise this value much. By contrast, 5 percent of well fibrillated Teflon produces an eight-fold increase in fracture toughness. Further process improvements should increase this factor to 20-30.

  13. Hybrid joining of polyamide and hydrogenated acrylonitrile butadiene rubber through heat-resistant functional layer of silane coupling agent

    Science.gov (United States)

    Sang, Jing; Sato, Riku; Aisawa, Sumio; Hirahara, Hidetoshi; Mori, Kunio

    2017-08-01

    A simple, direct adhesion method was developed to join polyamide (PA6) to hydrogenated acrylonitrile butadiene rubber (HNBR) by grafting a functional layer of a silane coupling agent on plasma functionalized PA6 surfaces. The functional layer of the silane coupling agent was prepared using a self-assembly method, which greatly improved the heat resistance of PA6 from 153 °C up to 325 °C and the resulting PA6/HNBR joints showed excellent adhesion properties with cohesive failure between PA6 and HNBR. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nanoscale infrared microscopy and chemical imaging (Nano-IR, AFM-IR) were employed to characterize the surfaces and interfaces. The Nano-IR analysis method was employed for the first time to analyze the chemical structures of the adhesion interfaces between different materials and to establish the interface formation mechanism. This study is of significant value for interface research and the study of adhesion between resins and rubbers. There is a promising future for heat-resistant functional layers on resin surfaces, with potential application in fuel hose composite materials for the automotive and aeronautical industries.

  14. Flame retardancy of polyamide 6 hybrid fibers: Combined effects of α-zirconium phosphate and ammonium sulfamate

    Directory of Open Access Journals (Sweden)

    Hengxue Xiang

    2017-06-01

    Full Text Available Synergistic effect between α-zirconium phosphate (α-ZrP and ammonium sulfamate (AS for enhanced flame retardant properties of Polyamide 6 (PA6 was investigated by using oxygen index instrument, cone calorimeter, thermogravimetric analyzer (TGA, Instron universal test machine and scanning electron microscopy (SEM. PA6/AS/α-ZrP ternary hybrid materials with various contents of α-ZrP and AS were fabricated by melt-mixing method. The result from flammability indicated that the Limiting oxygen index (LOI and Underwriters Laboratories-94 (UL-94 rating of PA6/AS/α-ZrP were significantly accelerated under the coordinating function of α-ZrP and AS. Moreover, the thermal stability for PA6/AS/α-ZrP studied by TGA also demonstrated this synergistic effect between α-ZrP and AS on the heat resistance. The effects of the usage amount of α-ZrP and AS on mechanical properties were analyzed by using uniaxial tensile test. It was found that the addition of AS provided negative effects on the tensile strength of PA6/AS/α-ZrP, however, the adverse trends that mentioned above could be overcome by using the well dispersed α-ZrP.

  15. Fabrication and characterization of drug-loaded nano-hydroxyapatite/polyamide 66 scaffolds modified with carbon nanotubes and silk fibroin

    Directory of Open Access Journals (Sweden)

    Yao MZ

    2016-11-01

    Full Text Available Meng-Zhu Yao,1 Ming-Yi Huang-Fu,1 Hui-Na Liu,1 Xia-Rong Wang,1 Xiaoxia Sheng,2 Jian-Qing Gao1 1Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, 2Hangzhou SoliPharma Co., Ltd, Hangzhou, Zhejiang, People’s Republic of China Abstract: Nano-hydroxyapatite/polyamide 66 (nHA/PA66 porous scaffolds were fabricated by a phase inversion method. Carbon nanotubes (CNTs and silk fibroin (SF were used to modify the surface of the nHA/PA66 scaffolds by freeze-drying and cross-linking. Dexamethasone was absorbed to the CNTs to promote the osteogenic differentiation of bone mesenchymal stem cells (BMSCs. The cell viability of BMSCs was investigated by changing the concentration of the CNT dispersion, and the most biocompatible scaffold was selected. In addition, the morphology and mechanical property of the scaffolds were investigated. The results showed that the nHA/PA66 scaffolds modified with CNTs and SF met the requirements of bone tissue engineering scaffolds. The dexamethasone-loaded CNT/SF-nHA/PA66 composite scaffold promoted the osteogenic differentiation of BMSCs, and the drug-loaded scaffolds are expected to function as effective bone tissue engineering scaffolds. Keywords: BMSCs, tissue engineering, porous scaffold, carbon nanotubes, silk fibroin, surface modification, dexamethasone

  16. Water Diffusion Mechanism in Carbon Nanotube and Polyamide Nanocomposite Reverse Osmosis Membranes: A Possible Percolation-Hopping Mechanism

    Science.gov (United States)

    Araki, Takumi; Cruz-Silva, Rodolfo; Tejima, Syogo; Ortiz-Medina, Josue; Morelos-Gomez, Aaron; Takeuchi, Kenji; Hayashi, Takuya; Terrones, Mauricio; Endo, Morinobu

    2018-02-01

    This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. The mechanism of water diffusion across reverse osmosis nanocomposite membranes made of carbon nanotubes (CNTs) and aromatic polyamide is not completely understood despite its high potential for desalination applications. While most of the groups have proposed that superflow inside the CNT might positively impact the water flow across membranes, here we show theoretical evidence that this is not likely the case in composite membranes because CNTs are usually oriented parallel to the membrane surface, not to mention that sometimes the nanotube cores are occluded. Instead, we propose an oriented diffusion mechanism that explains the high water permeation by decreasing the diffusion path of water molecules across the membranes, even in the presence of CNTs that behave as impermeable objects. Finally, we provide a comprehensive description of the molecular dynamics occurring in water desalination membranes by considering the bond polarizability caused by dynamic charge transfer and explore the use of molecular-dynamics-derived stochastic diffusion simulations. The proposed water diffusion mechanism offers an alternative and most likely explanation for the high permeation phenomena observed in CNTs and PA nanocomposite membranes, and its understanding can be helpful to design the next generation of reverse osmosis desalination membranes.

  17. SYNERGISTIC EFFECTS OF NOVOLAC-BASED CHAR FORMER WITH A PHOSPHORUS/NITROGEN-CONTAINING FLAME RETARDANT IN POLYAMIDE 6

    Institute of Scientific and Technical Information of China (English)

    Wei-cheng Xiong; Li Chen; De-yi Wang; Fei Song; Yu-zhong Wang

    2012-01-01

    The synergistic effect of phosphorus oxynitride (PON) with a novolac-based char former modified by salification (NA-metal salt) on the flame retardance of polyamide 6 (PA6) was investigated.For this purpose,various flame-retardant PA6 systems were melt-compounded with PON,PON/NA,PON/NA-V2O5 and PON/NA-Fe2O3,and their flame retardance was evaluated by measuring the limiting oxygen index (LOI) values and UL-94 vertical burning ratings.The results showed that,compared with the PA6/PON/NA system,the combination of two char formers (NA-V2O5,NA-Fe2O3) with PON could obviously improve the char formation and flame retardance of PA6.The flame retardance and cone calorimetric analyses showed the stronger synergism as well as the better flame retardant performance of PON/NA-Fe2O3 flame retardant system.The effects of different char formers on the flame retardance and thermal stability of this system were also discussed.

  18. Evaluation of Thermal and Thermomechanical Behaviour of Bio-Based Polyamide 11 Based Composites Reinforced with Lignocellulosic Fibres

    Directory of Open Access Journals (Sweden)

    Helena Oliver-Ortega

    2017-10-01

    Full Text Available In this work, polyamide 11 (PA11 and stone ground wood fibres (SGW were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of PA11-based composites were studied. Natural fibres have lower degradation temperatures than PA11, thus, composites showed lower onset degradation temperatures than PA11, as well. The thermal transition and the semi-crystalline structure of the composites were similar to PA11. On the other hand, when SGW was submitted to an annealing treatment, the composites prepared with these fibres increased its crystallinity, with increasing fibre contents, compared to PA11. The differences between the glass transition temperatures of annealed and untreated composites decreased with the fibre contents. Thus, the fibres had a higher impact in the composites mechanical behaviour than on the mobility of the amorphous phase. The crystalline structure of PA11 and PA11-SGW composites, after annealing, was transformed to α’ more stable phase, without any negative impact on the properties of the fibres.

  19. Nanocomposites of polyamide 6/residual monomer with organic-modified montmorillonite and their nanofibers produced by electrospinning

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Gonçalves Beatrice

    2012-08-01

    Full Text Available Nanocomposites of an organic-modified montmorillonite (MMT and polyamide 6 (PA6 with a residual monomer were produced by melt mixing in a torque rheometer. By wide angle X-rays diffraction (WAXD, intercalated/exfoliated structures were observed in the PA6/MMT nanocomposites with 3 and 5 wt. (% of MMT; on the other hand, when 7 wt. (% of MMT was added, a nanocomposite with exfoliated structures was obtained due to the predominant linking reactions between the residual monomer and the "nanoclays" organic surfactant. Solutions of these PA6/MMT nanocomposites at 15, 17 and 20 wt. (% in formic acid were prepared. The 3 and 5 wt. (% nanocomposites were successfully electrospun; however, electrospinning of the 7 wt. (% nanocomposite was not possible. WAXD, scanning and transmission electron microscopy results showed that the 3 and 5 wt. (% nanofibers with average diameter between 80-250 nm had exfoliated structures. These results indicate that the high elongational forces developed during the electrospinning process changed the initial intercalated/exfoliated structure of the nanocomposites to an exfoliated one.

  20. Quantitation of Pyrrole-Imidazole Polyamide in Rat Plasma by High-Performance Liquid Chromatography Coupled with UV Detection

    Directory of Open Access Journals (Sweden)

    Tomonori Kamei

    2012-01-01

    Full Text Available A simple and robust method using high-performance liquid chromatography with UV detection was developed and validated for the determination of six pyrrole-imidazole (PI polyamides (HN.49, TGF-β1f, TGF-β1t, HN.50f, HN.50t, and LOX-1 in rat plasma. After the plasma proteins were precipitated with methanol containing phenacetin as an internal standard, the analytes were separated on a Luna C18 (2 (5 μm, 4.6×150 mm. Calibration curves were linear over the range of 0.5 to 200 μg/mL for HN.49, 0.25 to 200 μg/mL for TGF-β1f, TGF-β1t, HN.50t, and LOX-1, 1 to 200 μg/mL for HN.50f in rat plasma. The inter- and intraday precision were below 15%, and the accuracy was within 15% at the quality controls. The validated method was successfully applied to sample analysis for the pharmacokinetic study.

  1. The improvement of mechanical and thermal properties of polyamide 12 3D printed parts by fused deposition modelling

    Directory of Open Access Journals (Sweden)

    T. N. A. T. Rahim

    2017-12-01

    Full Text Available This paper addresses the utilisation of fused deposition modelling (FDM technology using polyamide 12, incorporated with bioceramic fillers (i.e. zirconia and hydroxyapatite as a candidate for biomedical applications. The entire production process of printed PA12 is described, starting with compounding, filament wire fabrication and finally, FDM printing. The potential to process PA12 using this technique and mechanical, thermal and morphological properties were also examined. Commonly, a reduction of mechanical properties of printed parts would occur in comparison with injection moulded parts despite using the same material. Therefore, the mechanical properties of the samples prepared by injection moulding were also measured and applied as a benchmark to examine the effect of different processing methods. The results indicated that the addition of fillers improved or maintained the strength and stiffness of neat PA12, at the expense of reduced toughness and flexibility. Melting behaviours of PA12 were virtually insensitive to the processing techniques and were dependent on additional fillers and the cooling rate. Incorporation of fillers slightly lowered the melting temperature, however improved the thermal stability. In summary, PA12 composites were found to perform well with FDM technique and enabling the production of medical implants with acceptable mechanical performances for non-load bearing applications.

  2. Double dielectric barrier (DBD) plasma-assisted deposition of chemical stabilized nanoparticles on polyamide 6,6 and polyester fabrics

    Science.gov (United States)

    Ribeiro, A. I.; Modic, M.; Cvelbar, U.; Dinescu, G.; Mitu, B.; Nikiforov, A.; Leys, C.; Kuchakova, I.; Vanneste, M.; Heyse, P.; De Vrieze, M.; Carneiro, N.; Souto, A. P.; Zille, A.

    2017-10-01

    The development of new multifunctional textiles containing nanoparticles (NPs) has a special interest in several applications for pharmaceutical and medical products. Cu, Zn and Ag are the most promising antimicrobial NPs, exhibiting strong antibacterial activities. However, most of antimicrobial textiles coated with NPs are not able to perform a controlled release of NPs because of the high degree of aggregation. The aim of this study is to assess the effect of NPs stabilizers such as citrate, alginate and polyvinyl alcohol (PVA) in Cu, Zn and Ag NPs dispersions. The obtained dispersions were used to develop a new class of antibacterial NPs coatings onto polyamide 6,6 (PA66) and polyester fabrics (PES) by Double Dielectric Barrier (DBD) plasma discharge. Dynamic light scattering (DLS) was used to evaluate the best dispersing agent in terms of size, polydispersity index and zeta potential. Coating efficiency was evaluated by SEM, XPS and FTIR. The washing fastness of the coatings developed was also tested. The results show that the best dispersions were obtained using 2.5% of citrate for ZnO, 5% Alginate for Cu and 2.5% alginate for Ag NPs. SEM, XPS and FTIR analysis shows that DBD is an efficient deposition technique only for Ag and Cu NPs and that better perform in PA66 than PES fabric. The DBD deposition in air display similar results in term of NPS deposition of usually more efficient plasma jets using carrier gas such as N2 and Ar.

  3. Bone plate composed of a ternary nano-hydroxyapatite/polyamide 66/glass fiber composite: biomechanical properties and biocompatibility.

    Science.gov (United States)

    Qiao, Bo; Li, Jidong; Zhu, Qingmao; Guo, Shuquan; Qi, Xiaotong; Li, Weichao; Wu, Jun; Liu, Yang; Jiang, Dianming

    2014-01-01

    An ideal bone plate for internal fixation of bone fractures should have good biomechanical properties and biocompatibility. In this study, we prepared a new nondegradable bone plate composed of a ternary nano-hydroxyapatite/polyamide 66/glass fiber (n-HA/PA66/GF) composite. A breakage area on the n-HA/PA66/GF plate surface was characterized by scanning electron microscopy. Its mechanical properties were investigated using bone-plate constructs and biocompatibility was evaluated in vitro using bone marrow-derived mesenchymal stem cells. The results confirmed that adhesion between the n-HA/PA66 matrix and the glass fibers was strong, with only a few fibers pulled out at the site of breakage. Fractures fixed by the n-HA/PA66/GF plate showed lower stiffness and had satisfactory strength compared with rigid fixation using a titanium plate. Moreover, the results with regard to mesenchymal stem cell morphology, MTT assay, Alizarin Red S staining, enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction for alkaline phosphatase and osteocalcin showed that the n-HA/PA66/GF composite was suitable for attachment and proliferation of mesenchymal stem cells, and did not have a negative influence on matrix mineralization or osteogenic differentiation of mesenchymal stem cells. These observations indicate that the n-HA/PA66/GF plate has good biomechanical properties and biocompatibility, and may be considered a new option for internal fixation in orthopedic surgery.

  4. Interfacial Interaction in Anodic Aluminum Oxide Templates Modifies Morphology, Surface Area, and Crystallization of Polyamide-6 Nanofibers.

    Science.gov (United States)

    Xue, Junhui; Xu, Yizhuang; Jin, Zhaoxia

    2016-03-08

    Here, we demonstrated that, when the precipitation process of polyamide-6 (PA6) solution happens in cylindrical channels of an anodized aluminum oxide membrane (AAO), interface interactions between a solid surface, solvent, non-solvent, and PA6 will influence the obtained polymer nanostructures, resulting in complex morphologies, increased surface area, and crystallization changes. With the enhancing interaction of PA6 and the AAO surface, the morphology of PA6 nanostructures changes from solid nanofibers, mesoporous, to bamboo-like, while at the same time, metastable γ-phase domains increase in these PA6 nanostructures. Brunauer-Emmett-Teller (BET) surface areas of solid, bamboo-like, and mesoporous PA6 nanofibers rise from 16, 20.9, to 25 m(2)/g. This study shows that interfacial interaction in AAO template fabrication can be used in manipulating the morphology and crystallization of one-dimensional polymer nanostructures. It also provides us a simple and novel method to create porous PA6 nanofibers with a large surface area.

  5. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    International Nuclear Information System (INIS)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2002-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

  6. High-performance polyamide thin-film-nanocomposite reverse osmosis membranes containing hydrophobic zeolitic imidazolate framework-8

    KAUST Repository

    Duan, Jintang

    2015-02-01

    A hydrophobic, hydrothermally stable metal-organic framework (MOF) - zeolitic imidazolate framework-8 (ZIF-8) was successfully incorporated into the selective polyamide (PA) layer of thin-film nanocomposite (TFN) membranes for water desalination. The potential advantages of ZIF-8 over classic hydrophilic zeolite used in TFNs include: i) theoretically faster water transport within the framework and ii) better compatibility with the PA matrix. The TFN membranes were characterized with SEM, TEM, AFM, XPS, water contact angle measurements and reverse osmosis tests under 15.5bar hydraulic pressure with 2000ppm NaCl solution. Lab-made, nano-sized (~200nm) ZIF-8 increased water permeance to 3.35±0.08L/m2·h·bar at 0.4% (w/v) loading, 162% higher than the pristine PA membranes; meanwhile, high NaCl rejection was maintained. The TFN surface was less crosslinked and more hydrophilic than that of the pristine PA. A filler encapsulation mechanism was proposed for the effects of filler on TFN membrane surface morphology and properties. This study experimentally verified the potential use of ZIF-8 in advanced TFN RO membranes.

  7. Time dependent voiding mechanisms in polyamide 6 submitted to high stress triaxiality: experimental characterisation and finite element modelling

    Science.gov (United States)

    Selles, Nathan; King, Andrew; Proudhon, Henry; Saintier, Nicolas; Laiarinandrasana, Lucien

    2017-08-01

    Double notched round bars made of semi-crystalline polymer polyamide 6 (PA6) were submitted to monotonic tensile and creep tests. The two notches had a root radius of 0.45 mm, which imposes a multiaxial stress state and a state of high triaxiality in the net (minimal) section of the specimens. Tests were carried out until the failure occurred from one of the notches. The other one, unbroken but deformed under steady strain rate or steady load, was inspected using the Synchrotron Radiation Computed Tomography (SRCT) technique. These 3D through thickness inspections allowed the study of microstructural evolution at the peak stress for the monotonic tensile test and at the beginning of the tertiary creep for the creep tests. Cavitation features were assessed with a micrometre resolution within the notched region. Spatial distributions of void volume fraction ( Vf) and void morphology were studied. Voiding mechanisms were similar under steady strain rates and steady loads. The maximum values of Vf were located between the axis of revolution of the specimens and the notch surface and voids were considered as flat cylinders with a circular basis perpendicular to the loading direction. A model, based on porous plasticity, was used to simulate the mechanical response of this PA6 material under high stress triaxiality. Both macroscopic behaviour (loading curves) and voiding micro-mechanisms (radial distributions of void volume fraction) were accurately predicted using finite element simulations.

  8. Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants.

    Science.gov (United States)

    Abe, Yutaka; Mutsuga, Motoh; Ohno, Hiroyuki; Kawamura, Yoko; Akiyama, Hiroshi

    2016-01-01

    Small amounts of cyclic monomers and oligomers are present in polyamide (PA)-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam) and PA66 (a polymer of 1,6-diaminohexane and adipic acid). Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of migration into food simulants were quantified by high-performance liquid chromatography/mass spectrometry using purchased PA6 monomer and isolated PA66 monomers, and isolated PA6 and PA66 oligomers as calibration standards. Their total residual levels among 23 PA-based kitchen utensils made from PA6, PA66, and copolymers of PA6 and PA66 (PA6/66) ranged from 7.8 to 20 mg/g. Using water, 20% ethanol, and olive oil as food simulants, the total migration levels of the PA monomers and oligomers ranged from 0.66 to 100 μg/cm2 under most examined conditions. However, the total migration levels of the PA66 monomer and oligomers from PA66 and PA6/66 kitchen utensils into 20% ethanol at 95°C were very high (1,700 and 2,200 μg/cm2, respectively) due to swelling by high-temperature ethanol.

  9. Comparison of mechanical properties for polyamide 12 composite-based biomaterials fabricated by fused filament fabrication and injection molding

    Science.gov (United States)

    Rahim, Tuan Noraihan Azila Tuan; Abdullah, Abdul Manaf; Akil, Hazizan Md; Mohamad, Dasmawati

    2016-12-01

    The emergence of 3D printing technology known as fused filament fabrication (FFF) has offered the possibility of producing an anatomically accurate, patient specific implant with more affordable prices. The only weakness of this technology is related to incompatibility and lack of properties of current material to be applied in biomedical. Therefore, this study aims to develop a new, polymer composite-based biomaterial that exhibits a high processability using FFF technique, strong enough and shows acceptable biocompatibility, and safe for biomedical use. Polyamide 12 (PA12), which meets all these requirements was incorporated with two bioceramic fillers, zirconia and hydroxyapatite in order to improve the mechanical and bioactivity properties. The obtained mechanical properties were compared with injection-molded specimens and also a commercial biomedical product, HAPEXTM which is composed of hydroxyapatite and polyethylene. The yield strength and modulus of the PA12 composites increased steadily with increasing filler loading. Although the strength of printed PA12 composites were reduced compared with injection molded specimen, but still higher than HAPEXTM material. The higher surface roughness obtained by printed PA12 was expected to enhance the cell adhesion and provide better implant fixation.

  10. A Controlled Design of Ripple-Like Polyamide-6 Nanofiber/Nets Membrane for High-Efficiency Air Filter.

    Science.gov (United States)

    Zhang, Shichao; Liu, Hui; Zuo, Fenglei; Yin, Xia; Yu, Jianyong; Ding, Bin

    2017-03-01

    The filtration capacity of fibrous media for airborne particles is restricted by their thick diameter, low porosity, and limited frontal area. The ability to solve this problem would have broad technological implications for various air filtration applications; despite many past efforts, it remains a great challenge to achieve. Herein, a facile and scalable strategy to fabricate the ripple-like polyamide-6 nanofiber/nets (PA-6 NF/N) air filter via combining electrospinning/netting technique with receiving substrate design is demonstrated. This proposed approach allows the scaffold filaments to orderly embed into 2D PA-6 nanonets layer with Steiner-tree structures and nanoscale diameter of ≈20 nm, resulting in the ripple-like membrane with extremely small pore size, highly porous structure, and hugely extended frontal surface, by facilely adjusting its pleat span and pleat pitch. These unique structural advantages enable the ripple-like PA-6 NF/N filter to filtrate the ultrafine particles with high removal efficiency of 99.996%, low air resistance of 95 Pa, and robust quality factor of >0.11 Pa -1 ; using its superlight weight of 0.9 g m -2 and physical sieving manner. This approach has the potentialities to give rise to a novel generation of filter media displaying enhanced filtration capacity for various applications thanks to their nanoscale features and designed macrostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The Effect of Toughening Combined with Microjet Cooling During Quenching (Solution Heat Treatment of Calcium Carbide-Modified CuAl10Fe4Ni4 Alloy on its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Górny Z.

    2013-03-01

    Full Text Available The work presents the results of the experimental research concerning the impact of a heat treatment (toughening of aluminum bronze CuAl10Fe4Ni4 on its mechanical properties. The conditions of the experiments and selected results are described. A detailed description of the effects of individual heat treatment conditions namely low and high temperature aging is also presented in the work.

  12. The Effect of Toughening Combined with Microjet Cooling During Quenching (Solution Heat Treatment of Calcium Carbide-modified CuAl10Fe4Ni4 Alloy on its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Z. Górny

    2013-01-01

    Full Text Available The work presents the results of the experimental research concerning the impact of a heat treatment (toughening of aluminum bronze CuAl10Fe4Ni4 on its mechanical properties. The conditions of the experiments and selected results are described. A detailed description of the effects of individual heat treatment conditions namely low and high temperature aging is also presented in the work.

  13. Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, Habib, E-mail: bagheri@sharif.edu [Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Azadi Av., P.O. Box 11365-9516, Tehran (Iran, Islamic Republic of); Aghakhani, Ali; Baghernejad, Masoud; Akbarinejad, Alireza [Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Azadi Av., P.O. Box 11365-9516, Tehran (Iran, Islamic Republic of)

    2012-02-24

    A novel solid phase microextraction (SPME) fiber was fabricated by electrospinning method in which a polymeric solution was converted to nanofibers using high voltages. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three dimensional structure. Polyamide (nylon 6), due to its suitable characteristics was used to prepare the unbreakable SPME nanofiber. The scanning electron microscopy (SEM) images of this new coating showed a diameter range of 100-200 nm for polyamide nanofibers with a homogeneous and porous surface structure. The extraction efficiency of new coating was investigated for headspace solid-phase microextraction (HS-SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. Effect of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength and polyamide amount were investigated and optimized. In order to improve the chromatographic behavior of phenolic compounds, all the analytes were derivatized prior to the extraction process using basic acetic anhydride. The detection limits of the method under optimized conditions were in the range of 2-10 ng L{sup -1}. The relative standard deviations (RSD) (n = 3) at the concentration level of 1.7-6.7 ng mL{sup -1} were obtained between 1 and 7.4%. The calibration curves of chlorophenols showed linearity in the range of 27-1330 ng L{sup -1} for phenol and monochlorophenols and 7-1000 ng L{sup -1} for dichloro and trichlorophenols. Also, the proposed method was successfully applied to the extraction of phenol and chlorophenols from real water samples and relative recoveries were between 84 and 98% for all the selected analytes except for 2,4,6 tricholophenol which was between 72 and 74%.

  14. Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples

    International Nuclear Information System (INIS)

    Bagheri, Habib; Aghakhani, Ali; Baghernejad, Masoud; Akbarinejad, Alireza

    2012-01-01

    A novel solid phase microextraction (SPME) fiber was fabricated by electrospinning method in which a polymeric solution was converted to nanofibers using high voltages. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three dimensional structure. Polyamide (nylon 6), due to its suitable characteristics was used to prepare the unbreakable SPME nanofiber. The scanning electron microscopy (SEM) images of this new coating showed a diameter range of 100–200 nm for polyamide nanofibers with a homogeneous and porous surface structure. The extraction efficiency of new coating was investigated for headspace solid-phase microextraction (HS-SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography–mass spectrometry (GC–MS) analysis. Effect of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength and polyamide amount were investigated and optimized. In order to improve the chromatographic behavior of phenolic compounds, all the analytes were derivatized prior to the extraction process using basic acetic anhydride. The detection limits of the method under optimized conditions were in the range of 2–10 ng L −1 . The relative standard deviations (RSD) (n = 3) at the concentration level of 1.7–6.7 ng mL −1 were obtained between 1 and 7.4%. The calibration curves of chlorophenols showed linearity in the range of 27–1330 ng L −1 for phenol and monochlorophenols and 7–1000 ng L −1 for dichloro and trichlorophenols. Also, the proposed method was successfully applied to the extraction of phenol and chlorophenols from real water samples and relative recoveries were between 84 and 98% for all the selected analytes except for 2,4,6 tricholophenol which was between 72 and 74%.

  15. Poly(amic acid)s and their poly(amide imide) counterparts containing azobenzene moieties: Characterization, imidization kinetics and photochromic properties

    Energy Technology Data Exchange (ETDEWEB)

    Konieczkowska, Jolanta [Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 M. Curie-Sklodowska Str., 41-819 Zabrze (Poland); Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice (Poland); Janeczek, Henryk [Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 M. Curie-Sklodowska Str., 41-819 Zabrze (Poland); Kozanecka-Szmigiel, Anna, E-mail: annak@if.pw.edu.pl [Faculty of Physics, Warsaw University of Technology, 75 Koszykowa Str., 00-662 Warszawa (Poland); Schab-Balcerzak, Ewa, E-mail: eschab-balcerzak@cmpw-pan.edu.pl [Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 M. Curie-Sklodowska Str., 41-819 Zabrze (Poland)

    2016-09-01

    We report on a series of novel photochromic poly(amide imide)s and their poly(amic acid) precursors bearing azobenzene chromophores as the side groups. The chemical structures of the polymers were designed so that they exhibited an enhanced thermal stability combined with a large and stable birefringence photogenerated by light of the wavelengths belonging to a wide spectral range. The polymers possessed rigidly attached azochromophores in the content of either one or two per a repeating unit, which in the latter case differed in their structures. The imidization kinetics of the poly(amic acid)s was investigated by differential scanning calorimetry and the kinetic parameters were estimated using Ozawa and Kissinger methods. Measurements of the selected physical properties of the polymers, such as solubility, supramolecular structure, linear absorption, thermal stability, glass transition and photochromic response were performed and used for determination of the structure-property relations. The measurements of photochromic properties showed a very efficient generation of optical anisotropy upon blue and violet irradiation, for both the poly(amide imide)s containing two different chromophores in the repeating unit and for their precursors. For these poly(amide imide)s and for their precursors an exceptionally slow decrease in the photoinduced optical anisotropy in the dark was also observed. - Highlights: • Three azopoly(amide imide)s were obtained from azopoly(amic acid)s. • Chosen physicochemical properties and photochromic responses were measured. • Desired optical response was found for polymers with two azo-dyes in repeating unit. • Structure-property relations were shown.

  16. Synthesis and Characterization of Novel Polyamide and Polyhydrazides Based on the 6,6´-disubstituted-2,2´-bipyridine

    OpenAIRE

    ŞENGÜL, Abdurrahman; ARSLAN, Hülya

    2014-01-01

    The monomers namely 6,6'-dicarbonylchloride-2,2'-bipyridine (1) and 6,6'-dihydrazine-2,2'-bipyridine (2) were synthesized and characterized thoroughly. The polyhydrazides (PHZ1 and PHZ2) were obtained by direct polycondensation of 2 with terephtaloylchloride (TPCl}), and novel polyamide (PA1) by direct polycondensation of 1 with hexametyhlenediamine (HMDA}). Polymers with low PDIs were generated in all cases (PD \\sim 1.02-1.3). The polymers were c...

  17. Structural and morphological characteristics of composite: polyamide 6/ferrite nickel; Caracteristicas morfologicas e estruturais do composito: poliamida 6/ferrita de niquel

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, P.C.; Santos, P.T.A.; Silva, T.R.G.; Araujo, E.M.; Costa, A.C.F.M., E-mail: patricia.fernandes24@hotmail.co [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2010-07-01

    This study aims to evaluate the structural and morphological characteristics of a composite polyamide 6 with 50% loading of nickel ferrite. The ferrite was obtained by combustion synthesis and calcined in muffle furnace at 700 deg C. The polymer matrix was previously dried in vacuum oven at 80 deg C / 48 h to eliminate moisture. The composites were characterized by XRD and SEM. XRD results show the incorporation of cargo in the matrix, and that increasing temperature led to a considerable increase in crystallinity. The particle size of the load in the matrix was changed by increasing temperature. (author)

  18. Reinforcement of the Gas Barrier Properties of Polyethylene and Polyamide Through the Nanocomposite Approach: Key Factors and Limitations

    Directory of Open Access Journals (Sweden)

    Picard E.

    2015-02-01

    Full Text Available In this study, polyamide 6 (PA6 and polyethylene (PE nanocomposites were prepared from melt blending and a detailed characterization of the nanocomposite morphology and gas barrier properties was performed. The choice of the organoclay was adapted to each polymer matrix. Exfoliated morphology and improved gas transport properties were obtained by melt mixing the polar PA6 matrix and the organoclay, whereas a microcomposite with poor barrier properties was formed from the binary PE/organomodified clay mixture. Different modified polyethylenes were examined as compatibilizers for the polyethylene/organoclay system. The effect of compatibilizer molar mass, polarity and content was investigated on the clay dispersion and on the gas barrier properties. The optimal compatibilizer to clay weight ratio was found to be equal to 4 whatever the compatibilizer. However, a high degree of clay delamination was obtained with the high molar mass compatibilizer whereas highly swollen clay aggregates resulted from the incorporation of the low molar mass interfacial agents. Contrary to the PA based system, the barrier properties of PE nanocomposites were not directly related to the clay dispersion state but resulted also from the matrix/clay interfacial interactions. Oxidized wax was identified as a very promising interfacial agent and a step by step study was performed to optimize the gas transport properties of the systems based on PE, oxidized wax and organoclay. In particular, an interesting combination of oxidized wax and high molar mass maleic anhydride grafted polyethylene allowing dividing the gas permeability by a factor 2 in comparison with neat PE was proposed.

  19. Tensile strength decreases and perfusion pressure of 3-holed polyamide epidural catheters increases in long-term epidural infusion.

    Science.gov (United States)

    Kim, Pascal; Meyer, Urs; Schüpfer, Guido; Rukwied, Roman; Konrad, Christoph; Gerber, Helmut

    2011-01-01

    Epidural analgesia is an established method for pain management. The failure rate is 8% to 12% due to technical difficulties (catheter dislocation and/or disconnection; partial or total catheter occlusion) and management. The mechanical properties of the catheters, like tensile strength and flow rate, may also be affected by the analgesic solution and/or the tissue environment. We investigated the tensile strength and perfusion pressure of new (n=20), perioperatively (n=30), and postoperatively (n=73) used epidural catheters (20-gauge, polyamide, closed tip, 3 side holes; Perifix [B. Braun]). To prevent dislocation, epidural catheters were taped (n=5) or fixed by suture (n=68) to the skin. After removal, mechanical properties were assessed by a tensile-testing machine (INSTRON 4500), and perfusion pressure was measured at flow rates of 10, 20, and 40 mL/h. All catheters demonstrated a 2-step force transmission. Initially, a minimal increase of length could be observed at 15 N followed by an elongation of several cm at additional forces (7 N). Breakage occurred in the control group at 23.5±1.5 N compared with 22.4±1.6 N in perioperative and 22.4±1.7 N in postoperative catheters (Ptensile strength, whereas perfusion pressure at clinically used flow rates (10 mL/h) increased significantly from 19±1.3 to 44±72 mm Hg during long-term (≥7 days) epidural analgesia (Ptensile strength or perfusion pressure. Epidural catheter use significantly increases the perfusion pressure and decreases the tensile strength. Copyright © 2011 by American Society of Regional Anesthesia and Pain Medicine

  20. Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma.

    Science.gov (United States)

    Zille, Andrea; Fernandes, Margarida M; Francesko, Antonio; Tzanov, Tzanko; Fernandes, Marta; Oliveira, Fernando R; Almeida, Luís; Amorim, Teresa; Carneiro, Noémia; Esteves, Maria F; Souto, António P

    2015-07-01

    This work studies the surface characteristics, antimicrobial activity, and aging effect of plasma-pretreated polyamide 6,6 (PA66) fabrics coated with silver nanoparticles (AgNPs), aiming to identify the optimum size of nanosilver exhibiting antibacterial properties suitable for the manufacture of hospital textiles. The release of bactericidal Ag(+) ions from a 10, 20, 40, 60, and 100 nm AgNPs-coated PA66 surface was a function of the particles' size, number, and aging. Plasma pretreatment promoted both ionic and covalent interactions between AgNPs and the formed oxygen species on the fibers, favoring the deposition of smaller-diameter AgNPs that consequently showed better immediate and durable antimicrobial effects against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Surprisingly, after 30 days of aging, a comparable bacterial growth inhibition was achieved for all of the fibers treated with AgNPs silver. Overall, the results suggest that instead of reducing the size of the AgNPs, which is associated with higher toxicity, similar long-term effects can be achieved with larger NPs (40-60 nm), even in lower concentrations. Because the antimicrobial efficiency of AgNPs larger than 30 nm is mainly ruled by the release of Ag(+) over time and not by the size and number of the AgNPs, this parameter is crucial for the development of efficient antimicrobial coatings on plasma-treated surfaces and contributes to the safety and durability of clothing used in clinical settings.

  1. Hybrid joining of polyamide and hydrogenated acrylonitrile butadiene rubber through heat-resistant functional layer of silane coupling agent

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Jing; Sato, Riku [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Aisawa, Sumio, E-mail: aisawa@iwate-u.ac.jp [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Hirahara, Hidetoshi [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Mori, Kunio [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan)

    2017-08-01

    Highlights: • We modify PA6 surface using silane coupling agent layer of APTMS to link HNBR. • APTMS greatly improved heat resistance of PA6 from 153 °C up to 325 °C. • A PA6/HNBR joined body was obtained, and it exhibits high adhesion strength with cohesive failure. • Chemical structures of the adhesion interfaces of PA6/HNBR were confirmed by Nano-IR. - Abstract: A simple, direct adhesion method was developed to join polyamide (PA6) to hydrogenated acrylonitrile butadiene rubber (HNBR) by grafting a functional layer of a silane coupling agent on plasma functionalized PA6 surfaces. The functional layer of the silane coupling agent was prepared using a self-assembly method, which greatly improved the heat resistance of PA6 from 153 °C up to 325 °C and the resulting PA6/HNBR joints showed excellent adhesion properties with cohesive failure between PA6 and HNBR. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nanoscale infrared microscopy and chemical imaging (Nano-IR, AFM-IR) were employed to characterize the surfaces and interfaces. The Nano-IR analysis method was employed for the first time to analyze the chemical structures of the adhesion interfaces between different materials and to establish the interface formation mechanism. This study is of significant value for interface research and the study of adhesion between resins and rubbers. There is a promising future for heat-resistant functional layers on resin surfaces, with potential application in fuel hose composite materials for the automotive and aeronautical industries.

  2. Compatibility of polyamide 6.6 and low density polyethylene polymeric blend using electron beam ionizing radiation

    International Nuclear Information System (INIS)

    Feitosa, Marcos Antonio Fernandes

    2008-01-01

    The plastic industry has recognized that mixture of polymers, called polymeric blends, yields new materials with improve properties and better features of those of the polymer blended. In most of the cases, blends are formed by immiscible components presenting separated phases, micro-structures or morphologies. One of the main factors for good mechanical performance is the interfacial adhesion of the blend components. The improvement of miscibility between the polymer components and the enhancement of blend performance is denominated of compatibility. This compatibility can be achieved by chemical methods or using ionizing radiation. The present work has as a main objective the study of the effect of the ionizing radiation from electron beam in the compatibility of the polyamide (PA) 6.6 and low density polyethylene (LDPE) 75%/25% wt blend, in the range of applied doses from 50 to 250 kGy. The compatibility effect was evaluated by mechanical test, which has shown improvement in the tensile strength and hardness properties and a reduction of the impact resistant. This mechanical behavior can be considered as a combination effect of the cross-linking, induced in the molecular structure on the polymers, and the increase of the miscibility of the blend components. The degree of compatibility was evaluated by the behavior of the glass transition temperatures (T g ) for the blend components obtained by dynamic mechanical analysis (DMA) measurements. The results have shown that the values of T g for PA 6.6 and LDPE get near by 8 deg C showing that the ionizing radiation have promoted a compatibility effect on the irradiated blend. (author)

  3. Effect of dynamic crosslinking on phase morphology and mechanical properties of polyamide 6,12/ethylene vinyl acetate copolymer blends

    Directory of Open Access Journals (Sweden)

    Fabrício Bondan

    2015-03-01

    Full Text Available The dynamic crosslinking of polyamide 6,12 and ethylene vinyl acetate (PA6,12/EVA blends in the mixing chamber of a torque rheometer was investigated. EVA was selectively crosslinked within the PA6,12 phase through free radical reactions using dycumil peroxide. The degree of EVA crosslinking in the PA12,6/EVA materials was estimated based on the gel content (insoluble EVA fraction. The PA6,12/EVA phase morphology was investigated by scanning electron microscopy. The mechanical properties were investigated by determining the tensile strength and hardness. The half-life time ( for homolytic scission of the dcumil peroxide (DCP was ~6s, and this time is longer than the dispersion time of the DCP in the blends. The addition of DCP resulted in increased torque values due to specific crosslinking in the EVA phase. For the pure EVA and its blends with PA6,12 the stabilized torque values increased proportionally with the amount of DCP in the system, due to a higher degree of crosslinking of the elastomeric phase. The gel content of the dynamically crosslinked blends increased with the amount of DCP incorporated until 4 phr. At 1 phr the gel content value was 2.6wt.%, while at 4 phr it was 17wt.%. For the polymer blend with 8 phr of DCP a lubricating effect contributed to reducing the gel content. The dynamically crosslinked blends, regardless of the amount of DCP added, showed a reduction in the mechanical properties, which is related to the morphological features of the system due to the low mechanical fragmentation during melt processing.

  4. Morphological and mechanical properties of polyamide 6/linear low density polyethylene blend compatibilized by electron-beam initiated mediation process

    International Nuclear Information System (INIS)

    Shin, Boo Young; Han, Do Hung

    2014-01-01

    The aim of this study was to compatibilize immiscible polyamide 6 (PA6)/linear low density polyethylene (LLDPE) blend by using electron-beam initiated mediation process. Glycidyl methacrylate (GMA) was chosen as a mediator for cross-copolymerization at the interface between PA6 and LLDPE. The exposure process was carried out to initiate cross-copolymerization by the medium of GMA at the interface between PA and LLDPE. The mixture of the PA6/LLDPE/GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam radiation at various doses at room temperature. To investigate the results of this compatibilization strategy, the morphological and mechanical properties of the blend were analyzed. Morphology study revealed that the diameters of the dispersion particles decreased and the interfacial adhesion increased with respect to irradiation doses. The elongation at break of the blends increases significantly with increasing irradiation dose up to 100 kGy while the tensile strength and the modulus increased nonlinearly with increasing irradiation dose. The reaction mechanisms of the mediation process with the GMA mediator at the interface between PA6 and LLDPE were estimated. - Highlights: • PA6/LLDPE blend was compatibilized by the electron-beam initiated mediation process. • Interfacial adhesion was significantly enhanced by the radiation initiated cross-copolymerization. • The elongation at break of blend irradiated at 100 kGy was 4 times higher than PA6. • The GMA as a mediator played a key role in the electron-beam initiated mediation process

  5. Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants.

    Directory of Open Access Journals (Sweden)

    Yutaka Abe

    Full Text Available Small amounts of cyclic monomers and oligomers are present in polyamide (PA-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam and PA66 (a polymer of 1,6-diaminohexane and adipic acid. Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of migration into food simulants were quantified by high-performance liquid chromatography/mass spectrometry using purchased PA6 monomer and isolated PA66 monomers, and isolated PA6 and PA66 oligomers as calibration standards. Their total residual levels among 23 PA-based kitchen utensils made from PA6, PA66, and copolymers of PA6 and PA66 (PA6/66 ranged from 7.8 to 20 mg/g. Using water, 20% ethanol, and olive oil as food simulants, the total migration levels of the PA monomers and oligomers ranged from 0.66 to 100 μg/cm2 under most examined conditions. However, the total migration levels of the PA66 monomer and oligomers from PA66 and PA6/66 kitchen utensils into 20% ethanol at 95°C were very high (1,700 and 2,200 μg/cm2, respectively due to swelling by high-temperature ethanol.

  6. Temperature-dependent rigidity and magnetism of polyamide 6 nanocomposites based on nanocrystalline Fe-Ni alloy of various geometries

    Directory of Open Access Journals (Sweden)

    M. A. A. Mohamed

    2016-10-01

    Full Text Available The focus of this study is to explore the potential use of Polyamide 6 nanocomposite reinforced with nanocrystalline (nc Fe20Ni80 alloy (Fe20Ni80/PA6 PNC in electromagnetic applications and provide understanding of how the alloy particle geometry is controlling the nanocomposite’s physical properties. Thermomechanical rigidity, room-temperature soft magnetic performance and thermal soft magnetic stability of Fe20Ni80/PA6 PNCs based on spherical-sea urchin alloy particles (UMB2-SU and necklace-like alloy chains (UMB2-NC have been investigated. Both PNCs have considerably superior bulk properties compared to neat PA6 and UMB2-SU exhibits the most remarkable overall performance. Morphological observations disclose two relevant phenomena: i improved dispersion and distribution of the SU alloy particles than the NC ones within PA6 matrix, leading to stronger filler-matrix interfacial interactions within the UMB2-SU as compared to the UMB2-NC and ii presence of constraint polymer regions in between alloy segments within the UMB2-SU that provide secondary reinforcing and soft magnetic mechanisms. Such phenomena along with the lower alloy crystallite size and PA6 γ-crystal type content within the UMB2-SU than in the UMB2-NC, are considered the main responsible factors for the distinctive performance of UMB2-SU. Overall, compared to various ferromagnetic nanocrystalline metallic materials, the research proposes the SU nc Fe20Ni80 alloy as a valuable nanofiller in polymers for electromagnetic applications.

  7. Reactive microencapsulation of carbon allotropes in polyamide shell-core structures and their transformation in hybrid composites with tailored electrical properties

    Directory of Open Access Journals (Sweden)

    F. Oliveira

    2016-02-01

    Full Text Available Polyamide 6 microcapsules (PAMC loaded with 2–10 wt% of different carbon allotropes: carbon black, multiwalled carbon nanotubes, carbon nanofibers and graphite were synthesized via activated anionic polymerization (AAROP of ε-caprolactam in solution performed in the presence of the respective micro- or nanosized loads. The forming high-molecular weight microporous PAMC showed typical diameters of 15–35 µm, the filler particles being entrapped in the core as proven by microscopy methods. The melt processing of the loaded microcapsules produced PA6/C-filler hybrid thermoplastic composites with homogeneous distribution of one or two C-fillers even at loads of up to 10% without any functionalization. The crystalline structure of all PAMC and molded composites was studied by thermal and X-ray diffraction methods focusing on possible structure modification during the transition from PAMC to molded plates. Mechanical tests in tension and electrical conductivity measurements showed that transforming loaded PAMC into composites by melt processing could be a facile and rapid method to fabricate polyamide composites with improved mechanical performance and tailored electrical and dielectric properties.

  8. Controlled Surface Modification of Polyamide 6.6 Fibres Using CaCl2/H2O/EtOH Solutions

    Directory of Open Access Journals (Sweden)

    Barbara Rietzler

    2018-02-01

    Full Text Available Polyamide 6.6 is one of the most widely used polymers in the textile industry due to its durability; however, it has rather limited modification potential. In this work, the controlled surface modification of polyamide 6.6 fibres using the solvent system CaCl2/H2O/EtOH was studied. The effects of solvent composition (relative proportions of the three components and treatment time on fibre properties were studied both in situ (with fibres in solvent and ex situ (after the solvent was washed off. The fibres swell and/or dissolve in the solvent depending on its composition and the treatment time. We believe that the fibre–solvent interaction is through complex formation between the fibre carbonyl groups and the CaCl2. On washing, there is decomplexation and precipitation of the polymer. The treated fibres exhibit greater diameters and surface roughness, structural difference between an outer shell and an inner core is observable, and water retention is higher. The solvent system is more benign than current alternatives, and through suitable tailoring of the treatment conditions, e.g., composition and time, it may be used in the design of advanced materials for storage and release of active substances.

  9. Structure-properties relationships of novel poly(carbonate-co-amide) segmented copolymers with polyamide-6 as hard segments and polycarbonate as soft segments

    Science.gov (United States)

    Yang, Yunyun; Kong, Weibo; Yuan, Ye; Zhou, Changlin; Cai, Xufu

    2018-04-01

    Novel poly(carbonate-co-amide) (PCA) block copolymers are prepared with polycarbonate diol (PCD) as soft segments, polyamide-6 (PA6) as hard segments and 4,4'-diphenylmethane diisocyanate (MDI) as coupling agent through reactive processing. The reactive processing strategy is eco-friendly and resolve the incompatibility between polyamide segments and PCD segments in preparation processing. The chemical structure, crystalline properties, thermal properties, mechanical properties and water resistance were extensively studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermal gravity analysis (TGA), Dynamic mechanical analysis (DMA), tensile testing, water contact angle and water absorption, respectively. The as-prepared PCAs exhibit obvious microphase separation between the crystalline hard PA6 phase and amorphous PCD soft segments. Meanwhile, PCAs showed outstanding mechanical with the maximum tensile strength of 46.3 MPa and elongation at break of 909%. The contact angle and water absorption results indicate that PCAs demonstrate outstanding water resistance even though possess the hydrophilic surfaces. The TGA measurements prove that the thermal stability of PCA can satisfy the requirement of multiple-processing without decomposition.

  10. A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites

    Science.gov (United States)

    Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

    2016-09-01

    A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas.

  11. A Multi-Response Optimization of Thrust Forces, Torques, and the Power of Tapping Operations by Cooling Air in Reinforced and Unreinforced Polyamide PA66

    Directory of Open Access Journals (Sweden)

    Rosario Domingo

    2018-03-01

    Full Text Available The use of cooling air during machining is an environmentally conscious procedure, and its applicability to different processes is a research priority. We studied tapping operations, an important operation in the assembly process, using cooling air with unreinforced polyamide (PA66 and polyamide reinforced with glass fiber (PA66-GF30. These materials are widely used in industry, but their behavior with respect to tapping has not been studied. We analyze the outcomes regarding the thrust force, torque, and power at cutting speeds between 15 and 60 m/min. The experimental tests were executed using cooling air at 22 °C, 2 °C, and −18 °C in dry conditions. The M12 × 1.75 mm taps were high-speed steel, with cobalt as the base material and coatings of TiN and AlCrN. To identify the more influential factors, an analysis of variance was performed, along with multi-response optimization to identify the desirability values. This optimization shows that the optimum for PA66can be found in environments close to 3 °C, while the optimum for PA66-GF30 is found at the minimal temperature studied (−18 °C. Thus, cooling air can be considered an adequate procedure for tapping operations, to increase the sustainability of the manufacturing processes.

  12. An efficient preparative procedure for main flavonoids from the peel of Trichosanthes kirilowii Maxim. using polyamide resin followed by semi-preparative high performance liquid chromatography.

    Science.gov (United States)

    Li, Aifeng; Sun, Ailing; Liu, Renmin; Zhang, Yongqing; Cui, Jichun

    2014-08-15

    In this study, a simple and efficient preparative procedure was developed for preparation of seven flavonoids from the peel of Trichosanthes kirilowii Maxim. using polyamide resin followed by semi-preparative high performance liquid chromatography (SPHPLC). First, the ethyl acetate fraction from the peel of T. kirilowii Maxim. obtained "prefractionation" using polyamide resin, which yielded two subfractions. And then the two subfractions were isolated by SPHPLC with an isocratic elution of methanol-water. Finally, seven known flavonoids were purified from 35 g of ethyl acetate extract including quercetin-3-O-[α-l-rhamnose (1→2)-β-d-glucopyranosyl]-5-O-β-d-glucopyranoside (19 mg), quercetin-3-O-rutinoside (24 mg), apigenin-7-O-β-d-glucopyranoside (10mg), diosmetin-7-O-β-d-glucopyranoside (45 mg), luteolin (21 mg), apigenin (15 mg), and diosmetin (56 mg). The purities of the compounds were determined by HPLC and the chemical structures were confirmed by UV and NMR analysis. In the present study, a simple, effective, and rapid procedure was established for preparative separation of multiple components from the peel of T. kirilowii Maxim. Furthermore, it was scalable and economical, so it was a promising basis for large-scale preparation of flavonoids from other plant extracts. Copyright © 2014. Published by Elsevier B.V.

  13. Amide Link Scission in the Polyamide Active Layers of Thin-Film Composite Membranes upon Exposure to Free Chlorine: Kinetics and Mechanisms.

    Science.gov (United States)

    Powell, Joshua; Luh, Jeanne; Coronell, Orlando

    2015-10-20

    The volume-averaged amide link scission in the aromatic polyamide active layer of a reverse osmosis membrane upon exposure to free chlorine was quantified at a variety of free chlorine exposure times, concentrations, and pH and rinsing conditions. The results showed that (i) hydroxyl ions are needed for scission to occur, (ii) hydroxide-induced amide link scission is a strong function of exposure to hypochlorous acid, (iii) the ratio between amide links broken and chlorine atoms taken up increased with the chlorination pH and reached a maximum of ∼25%, (iv) polyamide disintegration occurs when high free chlorine concentrations, alkaline conditions, and high exposure times are combined, (v) amide link scission promotes further chlorine uptake, and (vi) scission at the membrane surface is unrepresentative of volume-averaged scission in the active layer. Our observations are consistent with previously proposed mechanisms describing amide link scission as a result of the hydrolysis of the N-chlorinated amidic N-C bond due to nucleophilic attack by hydroxyl ions. This study increases the understanding of the physicochemical changes that could occur for membranes in treatment plants using chlorine as an upstream disinfectant and the extent and rate at which those changes would occur.

  14. Bulk chlorine uptake by polyamide active layers of thin-film composite membranes upon exposure to free chlorine-kinetics, mechanisms, and modeling.

    Science.gov (United States)

    Powell, Joshua; Luh, Jeanne; Coronell, Orlando

    2014-01-01

    We studied the volume-averaged chlorine (Cl) uptake into the bulk region of the aromatic polyamide active layer of a reverse osmosis membrane upon exposure to free chlorine. Volume-averaged measurements were obtained using Rutherford backscattering spectrometry with samples prepared at a range of free chlorine concentrations, exposure times, and mixing, rinsing, and pH conditions. Our volume-averaged measurements complement previous studies that have quantified Cl uptake at the active layer surface (top ≈ 7 nm) and advance the mechanistic understanding of Cl uptake by aromatic polyamide active layers. Our results show that surface Cl uptake is representative of and underestimates volume-averaged Cl uptake under acidic conditions and alkaline conditions, respectively. Our results also support that (i) under acidic conditions, N-chlorination followed by Orton rearrangement is the dominant Cl uptake mechanism with N-chlorination as the rate-limiting step; (ii) under alkaline conditions, N-chlorination and dechlorination of N-chlorinated amide links by hydroxyl ion are the two dominant processes; and (iii) under neutral pH conditions, the rates of N-chlorination and Orton rearrangement are comparable. We propose a kinetic model that satisfactorily describes Cl uptake under acidic and alkaline conditions, with the largest discrepancies between model and experiment occurring under alkaline conditions at relatively high chlorine exposures.

  15. Synthesis and DNA binding properties of 1-(3-aminopropyl)-imidazole-containing triamide f-Im*PyIm: a novel diamino polyamide designed to target 5'-ACGCGT-3'.

    Science.gov (United States)

    Satam, Vijay; Babu, Balaji; Porte, Alexander; Savagian, Mia; Lee, Megan; Smeltzer, Thomas; Liu, Yang; Ramos, Joseph; Wilson, W David; Lin, Shicai; Kiakos, Kostantinos; Hartley, John A; Lee, Moses

    2012-09-15

    A novel diamino/dicationic polyamide f-Im(*)PyIm (5) that contains an orthogonally positioned aminopropyl chain on an imidazole (Im(*)) moiety was designed to target 5'-ACGCGT-3'. The DNA binding properties of the diamino polyamide 5, determined by CD, ΔT(M), DNase I footprinting, SPR, and ITC studies, were compared with those of its monoamino/monocationic counterpart f-ImPyIm (1) and its diamino/dicationic isomer f-ImPy(*)Im (2), which has the aminopropyl group attached to the central pyrrole unit (Py(*)). The results gave evidence for the minor groove binding and selectivity of polyamide 5 for the cognate sequence 5'-ACGCGT-3', and with strong affinity (K(eq)=2.3×10(7) M(-1)). However, the binding affinities varied according to the order: f-ImPy(*)Im (2)>f-ImPyIm (1)≥f-Im(*)PyIm (5) confirming that the second amino group can improve affinity, but its position within the polyamide can affect affinity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Rigid-rod polyamides and polyimides derived from 4,3 ''-diamino-2 ',6 '-diphenyl- or di(4-biphenylyl)-p-terphenyl and 4-amino-4 ''-carboxy-2 ',6 '-diphenyl-p-terphenyl

    NARCIS (Netherlands)

    Spiliopoulos, IK; Mikroyannidis, JA; Tsivgoulis, GM

    1998-01-01

    4,3 "-Diamino-2',6'-diphenyl- or di(4-biphenylyl)p-terphenyl (3a or 3b) and 4-amino-4 "-carboxy-2',6'-diphenyl-p-terphenyl (6) were synthesized through pyrylium salts and used for the preparation of rigid-rod polyamides and polyimides. The polymers were characterized by inherent viscosity, elemental

  17. Properties and toughening mechanisms of PVA/PAM double-network hydrogels prepared by freeze-thawing and anneal-swelling.

    Science.gov (United States)

    Ou, Kangkang; Dong, Xia; Qin, Chengling; Ji, Xinan; He, Jinxin

    2017-08-01

    It is well known that preparation method of hydrogels has a significant effect on their properties. In this paper, freeze-thawing and anneal-swelling were applied to prepare poly(vinyl alcohol)/polyacrylamide (PVA/PAM) double-network hydrogels with covalently and physically cross-linked networks. The properties of these hydrogels were investigated and compared to control hydrogels. Results indicated that hydrogels fabricated by freeze-thawing show larger pores size and higher swelling capacity than those made by anneal-swelling and control hydrogels. Hydrogels prepared by anneal-swelling exhibit higher mechanical strength, energy dissipation, fracture energy, gel fraction and crystallinity than those made by freeze-thawing and control hydrogels. Physical cross-linking plays a key role in formation of physical-chemical double-network. The toughening mechanism of double-network hydrogel is related to their chain-fracture behavior and elasticity. The results also indicated that appropriate methods can endow hydrogels with specific microstructures and properties which would broaden current hydrogels research and applications in biomedical fields. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Graphene-and-Copper Artificial Nacre Fabricated by a Preform Impregnation Process: Bioinspired Strategy for Strengthening-Toughening of Metal Matrix Composite.

    Science.gov (United States)

    Xiong, Ding-Bang; Cao, Mu; Guo, Qiang; Tan, Zhanqiu; Fan, Genlian; Li, Zhiqiang; Zhang, Di

    2015-07-28

    Metals can be strengthened by adding hard reinforcements, but such strategy usually compromises ductility and toughness. Natural nacre consists of hard and soft phases organized in a regular "brick-and-mortar" structure and exhibits a superior combination of mechanical strength and toughness, which is an attractive model for strengthening and toughening artificial composites, but such bioinspired metal matrix composite has yet to be made. Here we prepared nacre-like reduced graphene oxide (RGrO) reinforced Cu matrix composite based on a preform impregnation process, by which two-dimensional RGrO was used as "brick" and inserted into "□-and-mortar" ordered porous Cu preform (the symbol "□" means the absence of "brick"), followed by compacting. This process realized uniform dispersion and alignment of RGrO in Cu matrix simultaneously. The RGrO-and-Cu artificial nacres exhibited simultaneous enhancement on yield strength and ductility as well as increased modulus, attributed to RGrO strengthening, effective crack deflection and a possible combined failure mode of RGrO. The artificial nacres also showed significantly higher strengthening efficiency than other conventional Cu matrix composites, which might be related to the alignment of RGrO.

  19. Ductile-reinforcement toughening in γ-TiAl intermetallic-matrix composites: Effects on fracture toughness and fatigue-crack propagation resistance

    International Nuclear Information System (INIS)

    Venkateswara Rao, K.T.; Ritchie, R.O.; Odette, G.R.

    1994-01-01

    The influence of the type, volume fraction, thickness and orientation of ductile phase reinforcements on the room temperature fatigue and fracture resistance of γ-TiAl intermetallic alloys is investigated. Large improvements in toughness compared to monolithic γ-TiAl are observed in both the TiNb- and Nb-reinforced composites under monotonic loading. Toughness increases with increasing ductile phase content, reinforcement thickness and strength; orientation effect are minimal. Crack-growth behavior is characterized by steep resistance curves primarily due to crack trapping/renucleation and extensive crack bridging by the ductile-phase particles. In contrast, under cyclic loading the influence of ductile phases on fatigue resistance is strongly dependent upon reinforcement orientation. Compared to monolithic γ-TiAl, improvements in fatigue-crack growth resistance are observed in TiNb-reinforced composites only in the face (C-L) orientation; crack-growth rates for the edge (C-R) orientation are actually faster in the composite. In comparison, Nb-particle reinforcements offer less toughening under monotonic loading but enhance the fatigue properties compared to TiNb reinforcements under cyclic loading

  20. Facile fabrication of epoxy-TiO2 nanocomposites: A critical analysis of TiO2 impact on mechanical properties and toughening mechanisms.

    Science.gov (United States)

    Goyat, M S; Rana, S; Halder, Sudipta; Ghosh, P K

    2018-01-01

    Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO 2 ) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (T g ) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Toughening of a Carbon-Fibre Composite Using Electrospun Poly(Hydroxyether of Bisphenol A Nanofibrous Membranes Through Inverse Phase Separation and Inter-Domain Etherification

    Directory of Open Access Journals (Sweden)

    Bronwyn Fox

    2011-11-01

    Full Text Available The interlaminar toughening of a carbon fibre reinforced composite by interleaving a thin layer (~20 microns of poly(hydroxyether of bisphenol A (phenoxy nanofibres was explored in this work. Nanofibres, free of defect and averaging several hundred nanometres, were produced by electrospinning directly onto a pre-impregnated carbon fibre material (Toray G83C at various concentrations between 0.5 wt % and 2 wt %. During curing at 150 °C, phenoxy diffuses through the epoxy resin to form a semi interpenetrating network with an inverse phase type of morphology where the epoxy became the co-continuous phase with a nodular morphology. This type of morphology improved the fracture toughness in mode I (opening failure and mode II (in-plane shear failure by up to 150% and 30%, respectively. Interlaminar shear stress test results showed that the interleaving did not negatively affect the effective in-plane strength of the composites. Furthermore, there was some evidence from DMTA and FT-IR analysis to suggest that inter-domain etherification between the residual epoxide groups with the pendant hydroxyl groups of the phenoxy occurred, also leading to an increase in glass transition temperature (~7.5 °C.

  2. Diagnostics of N2-Ar plasma mixture excited in A 13.56 MHz hollow cathode discharge system: Application to remote plasma treatment of polyamide surface

    International Nuclear Information System (INIS)

    Saloum, S.; Naddaf, M.; Al-khaled, B.

    2009-01-01

    N 2 -x % Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double langmuir probe, as a function of experimental parameters: Total pressure (5-33 Pa), and different fractions of argon (7≤ x ≤ 80), at a constant applied RF power of 300 W. N 2 dissociation degree has been investigated qualitatively by both actinometry method and the ratio of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N 2 second positive system at 337.1 nm. Both methods showed that the increase of argon fraction enhances the dissociation of N 2 , with a maximum at x=50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of N 2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 K and 12300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N 2 + density varies between 5.10 9 cm-3 and 1.4 10 10 cm -3 , and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide surface interaction, in the remote plasma zone, has been studied through optical emission spectroscopy analysis during plasma treatment of polyamide to monitor the possible emissions due to the polymer etching. An increase of atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from CN (B 2 Σ + -X 2 Σ + ) violet system were observed. The polyamide surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased. (author)

  3. Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

    Science.gov (United States)

    Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-02-01

    There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. New polyamide 12 grades for large diameter oil and pipes: VESTAMID{sup TM} LX9020 and VESTAMID{sup TM} LX9030

    Energy Technology Data Exchange (ETDEWEB)

    Dowe, Andreas; Baron, Christian; Coelho, Germano [Evonik Degussa GmbH, Arlington Heights, IL(United States)

    2008-07-01

    Polyamide 12 (PA 12) is a high performance polymer with outstanding mechanical properties and excellent chemical stability. It is the preferred material in many demanding applications, e. g. in the automotive industry for fuel lines of passenger cars or for air brake tubing's in trucks. In recent years PA 12 pipes underwent an approval process for the use in high-pressure gas distribution and offshore oil explorations. Also the applications lining and rehabilitation of pipes are under investigation. Especially the swelling behavior and the outstanding resistance to oil and other petrochemicals make VESTAMID{sup TM} the material of choice for rehabilitation and lining applications. The authors will give an introduction to the excellent technical performance of PA 12. The very high melt viscosity and stiffness of the newly developed VESTAMID{sup TM} grades enables new applications of PA 12 in oil and gas applications which will be discussed in this paper. (author)

  5. Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

    International Nuclear Information System (INIS)

    Kim, Sang-Woo; Seong, Dong Gi; Yi, Jin-Woo; Um, Moon-Kwang

    2016-01-01

    In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ε-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ε-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

  6. Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang-Woo; Seong, Dong Gi; Yi, Jin-Woo; Um, Moon-Kwang [Composites Research Division, Korea Institute of Materials Science (KIMS), Changwon, Gyeongnam, 642–831 (Korea, Republic of)

    2016-05-18

    In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ε-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ε-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

  7. Synthesis and characterization of hybrid organic-inorganic materials of polyamide-imide (PAI) and copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES)

    International Nuclear Information System (INIS)

    Demarchi, A.A.; Pezzin, S.H.

    2010-01-01

    In this work, organic-inorganic hybrids were obtained by adding copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES), prepared by sol-gel, to the polyamide-imide (PAI). The synthesis of PAI oligomer from trimellitic anhydride (TMA) and 4,4-diphenyl-methane diisocyanate (MDI), was monitored by FTIR, noting that two steps of 80 deg C and 120 deg C for 2 h each are sufficient to obtain it. PAI-copolysilsesquioxanes hybrids were characterized by FTIR, viscometry, thermogravimetry, NMR and microscopy. The spectrum of the PAI and PAI-hybrid copolysilsesquioxanes show the formation of amide and imide. Copolysilsesquioxanes with high levels of APES increased the viscosity and generated the PAI oligomer gelatinization, hindering the formation of uniform films. Gelatinization did not occur with copolysilsesquioxanes rich PTES, allowing the formation of homogeneous films improvements in thermal resistance. (author)

  8. [Study of relationship between powder-size gradation and mechanical properties of Zirconia toughened glass infiltrated nanometer-ceramic composite powder].

    Science.gov (United States)

    Chai, Feng; Xu, Ling; Liao, Yun-mao; Chao, Yong-lie

    2003-07-01

    The fabrication of all-ceramic dental restorations is challenged by ceramics' relatively low flexural strength and intrinsic poor resistance to fracture. This paper aimed at investigating the relationships between powder-size gradation and mechanical properties of Zirconia toughened glass infiltrated nanometer-ceramic composite (Al(2)O(3)-nZrO(2)). Al(2)O(3)-nZrO(2) ceramics powder (W) was processed by combination methods of chemical co-precipitation and ball milling with addition of different powder-sized ZrO(2). Field-emission scanning electron microscopy was used to determine the particle size distribution and characterize the particle morphology of powders. The matrix compacts were made by slip-casting technique and sintered to 1,450 degrees C and flexural strength and the fracture toughness of them were measured. 1. The particle distribution of Al(2)O(3)-nZrO(2) ceramics powder ranges from 0.02 - 3.5 micro m and among them the superfine particles almost accounted for 20%. 2. The ceramic matrix samples with addition of nZrO(2) (W) showed much higher flexural strength (115.434 +/- 5.319) MPa and fracture toughness (2.04 +/- 0.10) MPa m(1/2) than those of pure Al(2)O(3) ceramics (62.763 +/- 7.220 MPa; 1.16 +/- 0.02 MPa m(1/2)). The particle size of additive ZrO(2) may impose influences on mechanical properties of Al(2)O(3)-nZrO(2) ceramics matrix. Good homogeneity and reasonable powder-size gradation of ceramic powder can improve the mechanical properties of material.

  9. Synergistic effect of carbon nanotube as sintering aid and toughening agent in spark plasma sintered molybdenum disilicide-hafnium carbide composite

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Biswajyoti; Asiq Rahman, O.S.; Sribalaji, M [Materials Science and Engineering, Indian Institute of Technology Patna, Bihta Kanpa Road, Bihta, Patna, Bihar 801103 (India); Bakshi, Srinivasa Rao [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Keshri, Anup Kumar, E-mail: anup@iitp.ac.in [Materials Science and Engineering, Indian Institute of Technology Patna, Bihta Kanpa Road, Bihta, Patna, Bihar 801103 (India)

    2016-12-15

    Hafnium carbide (HfC) along with sintering aids was consolidated at a relatively lower temperature i.e. 1600 °C (i.e. T=~0.41 T{sub m}) under a uniaxial load of 50 MPa by spark plasma sintering. Two different sintering aids such as molybdenum disilicide (MoSi{sub 2}) and carbon nanotube (CNT) were added to enhance the densification and lower the extent of grain growth in the sintered pellets. Density of the sintered pellet increased from 96.0±0.8% in HfC +5 wt% MoSi{sub 2} (HM) to 99.0±0.5% with the addition of 2 wt% CNT in HfC+5 wt% MoSi{sub 2} (HMC) at sintering temperature of 1600 °C. Further, the extent of grain growth drastically reduced from 204% in HM to 50% in HMC. Analysis of linear shrinkage during densification revealed that CNT addition increased densification rate and decreased the time required to reach the density of 99.0±0.5% at 1600 °C. Increased densification and lower degree of grain growth could be due to the synergistic effect offered by the CNT, which are as follows: (i) Lubrication effect of CNT, (ii) Lower activation energy for grain boundary diffusion (iii) Reduction in liquid phase sintering temperature and (iv) Grain boundary pinning. Fracture toughness of the sintered HM and HMC composite was obtained using indentation technique. By the addition of 2 wt% CNT in HM, drastic increase of 91% in fracture toughness was seen. This significant improvement in fracture toughness was due to the enhanced densification and relatively lower grain size of HMC. Also crack bridging, crack deflection, crack arrest, CNT and graphene sheet pull-out and swording played major role in toughening of HMC pellet.

  10. Liquid and Gas Permeation Studies on the Structure and Properties of Polyamide Thin-Film Composite Membranes

    KAUST Repository

    Duan, Jintang

    2014-11-01

    This research was undertaken to improve the understanding of structure-property-performance relationships in crosslinked polyamide (PA) thin-film composite (TFC) membranes as characterized by liquid and gas permeation studies. The ultrathin PA selective layer formed by interfacial polymerization between meta-phenylene diamine and trimesoyl chloride was confirmed to contain dense polymer matrix regions and defective regions in both dry and hydrated states. The first part of this research studied the effect of non-selective convection through defective regions on water flux and solute flux in pressure-assisted forward osmosis (PAFO). Through systematic comparison with cellulose triacetate (CTA) and PEBAX-coated PA-TFC membranes, the existence of defects in pristine, hydrated PA-TFC membranes was verified, and their effects were quantified by experimental and modeling methods. In the membrane orientation of selective layer facing the draw solution, water flux increases of up to 10-fold were observed to result from application of low hydraulic pressure (1.25 bar). Convective water flux through the defects was low (< 1% of total water flux for PA-TFC membranes) and of little consequence in practical FO or reverse osmosis (RO) applications. However, it effectively mitigated the concentration polarization in PAFO and therefore greatly increased the diffusive flux through the dense regions. The second part of this research characterized the structures of the PA material and the PA selective layer by gas adsorption and gas permeation measurements. Gas adsorption isotherms (N2 at 77K, CO2 at 273K) confirmed the microporous nature of PA in comparison with dense CTA and polysulfone materials. Gas permeation through the commercial PA-TFC membranes tested occurred primarily in the defective regions, resulting in Knudsen gas selectivity for various gas pairs. Applying a Nafion coating layer effectively plugged the defects and allowed gas permeation through the dense PA regions

  11. Chemical and structural changes in polyamide based organic–inorganic hybrid materials upon incorporation of SeS{sub 2}O{sub 6}{sup 2−} precursor

    Energy Technology Data Exchange (ETDEWEB)

    Krylova, V.; Dukstienė, N.; Žalenkienė, S. [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu st. " 1" 9" , LT-50254, Kaunas (Lithuania); Baltrusaitis, J., E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

    2017-01-15

    Highlights: • We investigated deposited and diffused K{sub 2}SeS{sub 2}O{sub 6} into polyamide 6 (PA 6). • AAS showed Se:S molar ratio = 1:2 within the PA. • Various decomposition products were detected within the polymer. • Measured bandgap shifted towards lower light absorption energies. - Abstract: Composite organic-inorganic functional materials are of significant importance in various applications of science and technology. In this work, physicochemical characterization of such composite materials obtained after the exposure of polyamide PA 6 to K{sub 2}SeS{sub 2}O{sub 6} precursor solution was performed. Chalcogenized polymer surface was characterized using X-ray diffraction, infrared, and UV–vis spectroscopies while their bulk chemical analysis was performed using atomic absorption spectroscopy. Crystallite size was not found to change with the exposure to K{sub 2}SeS{sub 2}O{sub 6} precursor but PA 6 chain–chain separation decreased. Importantly, infrared and X-ray analyses showed chemical bonding taking place between the PA 6 and SeS{sub 2}O{sub 6}{sup 2−} ions via −NH− functional group. A distinct change in bandgap, E{sub g}, value was observed in UV–vis spectra due to the presence of SeS{sub 2}O{sub 6}{sup 2−}, SeSO{sub 3}{sup 2−} and Se{sub 2}S{sub 2}O{sub 6}{sup 2−} ions formed via decomposition of the precursor material in acidic medium. After extended 4 h chalcogenation a distinct absorption due to the elemental selenium was also observed as obtained from Tauc plots.

  12. Study of the effect of ionizing radiation on properties of polyamide 6 with fibreglass reinforcement; Estudo do efeito da radiacao ionizante sobre as propriedades da poliamida 6 com reforco de fibra de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Clovis

    2007-07-01

    It is each time more common the use of polymers reinforced with fibreglass in the domestic market. Between them it is used polyamide 6 that it presents good tension resistance, to the impact and the humidity absorption compared with non-reinforced, being also at the present time used in the automobile industry in parts underneath the hood, especially in the radiator frames. The aim of this work is to study the effect of ionizing radiation on properties of polyamide 6 with fibreglass reinforcement, undergone to different radiation doses. Samples were prepared and irradiated on JOB 188 accelerator with an electron beam energy of 1.5 MeV in air with different doses (100 to 600 kGy) and a dose rate of 22.61 kGy/h. Afterward the irradiation, the properties of the samples of irradiated polyamide 6 with fibreglass reinforcement were evaluated and compared with the samples non-irradiated. It evidenced that the mechanical properties flexural resistance and tension resistance increased and the resistance to the impact decreased. Regarding the thermal properties of the temperature of fusing decreased of 224,4 deg C for 212,5 deg C but the loss of mass ahead of the constant increase of the temperature also decreased. In the property of resistance to the glow wire the polyamide 6 with fibreglass reinforcement had a good performance. The images caught for Scanning Electronic Microscopy show that the irradiation provoked a good integration enters the fibreglass and polymer what was responsible for the good performance in the property of resistance to the glow wire. (author)

  13. Utilization of rice husk ash as filler for polyamide 6 and ionizing radiation effect studies on this composite;Utilizacao da cinza da casca de arroz como carga em matriz de poliamida 6 submetida a radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Ferro, Waldir Pedro

    2009-07-01

    In order to improve the dimensional stability, as well as, electrical, mechanical and thermal properties of polymers, new filler to this purpose has been developed. The mos applied filler to propitiate the features previously mentioned are the glass and carbon fibers, the mineral filler as the calcium carbonate, the talc and the micro glass sphere. The main aim of this work was to study the rice husk ash as filler for polyamide 6 and ionizing radiation effect studies on this composite, irradiated by electron beam at different doses, since it is constituted of at least 90% of silicon dioxide, and compared with the talc which is the most applied mineral filler. This comparison was made from a compound made through the refined rice husk ash and the polyamide 6 (PA 6), which is one of the main engineering plastic with applications in several productive areas. The samples were injected and irradiated in a electron accelerator. Afterwards, their mechanical and thermal properties were measured. It was also inject automotive parts to verify the processing of the PA 6 with CCA. The results showed that the use of the rice husk ash as filler for polyamide 6 composite is technically and economically viable. The irradiation of the studied composite (PA 6 with 30% of rice husk ash) did not provide any improvement for the mechanical and thermal properties previously appraised. (author)

  14. Reconciling in vivo and in vitro kinetics of the polymorphic transformation in zirconia-toughened alumina for hip joints: III. Molecular scale mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Pezzotti, Giuseppe, E-mail: pezzotti@kit.ac.jp [Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto (Japan); Bal, B. Sonny [Department of Orthopaedic Surgery, University of Missouri, Columbia, MO 65212 (United States); Amedica Corporation, 1885 West 2100 South, Salt Lake City, UT 84119 (United States); Zanocco, Matteo; Marin, Elia [Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto (Japan); Sugano, Nobuhiko [Department of Medical Engineering for Treatment of Bone and Joint Disorders, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0854 (Japan); McEntire, Bryan J. [Amedica Corporation, 1885 West 2100 South, Salt Lake City, UT 84119 (United States); Zhu, Wenliang, E-mail: wlzhu2002@hotmail.com [Department of Medical Engineering for Treatment of Bone and Joint Disorders, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0854 (Japan)

    2017-02-01

    Understanding the intrinsic reason(s) for the enhanced tetragonal to monoclinic (t → m) polymorphic phase transformation observed on metal-stained surfaces of zirconia-toughened alumina (ZTA) requires detailed knowledge of off-stoichiometry reactions at the molecular scale. In this context, knowledge of the mechanism(s) for oxygen vacancy creation or annihilation at the material surface is a necessary prerequisite. The crucial aspect of the surface destabilization phenomenon, namely the availability of electrons and holes that allow for vacancy creation/annihilation, is elucidated in this paper. Metal-enhanced alterations of the oxygen sublattice in both Al{sub 2}O{sub 3} and ZrO{sub 2} of the ZTA composite play a decisive role in accelerating the polymorphic transformation. According to spectroscopic evidences obtained through nanometer-scale analyses, enhanced annihilation of oxygen vacancies triggers polymorphic transformation in ZrO{sub 2} near the metal stain, while the overall Al{sub 2}O{sub 3} lattice tends to dehydroxylate by forming oxygen vacancies. A mechanism for chemically driven “reactive metastability” is suggested, which results in accelerating the polymorphic transformation. The Al{sub 2}O{sub 3} matrix is found to play a key-role in the ZrO{sub 2} transformation process, with unambiguous confirmation of oxygen and hydrogen transport at the material surface. It is postulated that this transport is mediated by migration of dissociated O and H elements at the surface of the stained transition metal as they become readily available by the thermally activated surrounding. - Graphical abstract: Metal-enhanced alterations of the oxygen sublattice in both Al{sub 2}O{sub 3} and ZrO{sub 2} of the ZTA composite play a decisive role in the polymorphic transformation. According to spectroscopic evidence obtained through nanometer-scale analyses, enhanced annihilation of oxygen vacancies in Al{sub 2}O{sub 3} and ZrO{sub 2} occurs near the metal stain

  15. Effects of a silicone-coated polyamide net dressing and calcium alginate on the healing of split skin graft donor sites: a prospective randomised trial.

    LENUS (Irish Health Repository)

    O'Donoghue, J M

    2012-02-03

    An open randomised prospectively controlled trial was performed to assess the healing efficacy, slippage rate and degree of discomfort on removal of calcium alginate and a silicone-coated polyamide net dressing on split skin graft donor sites. Sixteen patients were randomised to the calcium alginate group and 14 to the silicone-coated group. The donor sites were assessed at days 7, 10, 14 and up to day 21. The mean time to healing in the calcium alginate group was 8.75 +\\/- 0.78 days (range 7 to 14 days) compared to 12 +\\/- 0.62 days (range 7 to 16 days) for the silicone-coated group (p < 0.01). Although more silicone-coated dressings slipped (5 versus 1), the difference was not statistically significant. Pain during the first dressing change was assessed using a visual analogue pain scale. Although no significant differences were found between the groups, it was necessary to change the dressing protocol in the silicone-coated arm of the trial after entering the first two patients. Overlaid absorbent gauze adhered to the donor site through the fenestrations in the dressing necessitating the placement of paraffin gauze between the experimental dressing and the overlying cotton gauze. There was one infection in the study, occurring in the alginate group. Based on these results we recommend calcium alginate as the dressing of choice for split skin graft donor sites.

  16. Optical, thermal and combustion properties of self-colored polyamide nanocomposites reinforced with azo dye surface modified ZnO nanoparticles

    Science.gov (United States)

    Hajibeygi, Mohsen; Shabanian, Meisam; Omidi-Ghallemohamadi, Mehrdad; Khonakdar, Hossein Ali

    2017-09-01

    New self-colored aromatic-polyamide (PA) nanocomposites containing azo and naphthalene chromophores were prepared with azo-dye surface-modified ZnO nanoparticles (SMZnO) using solution method in dimethylformamide. The X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results showed the uniform distribution for ZnO nanoparticles in the PA matrix. The UV-vis spectra of PA/ZnO nanocomposites (PANC) showed a blue shift as well as reduction in absorbance intensities and the photoluminescence studies revealed that the increasing intensities of the violet emission in SMZnO loading. From thermo gravimetric analysis (TGA), the temperature at 10% mass loss (T10) increased from 291.8 °C to 387.6 °C for PANC containing 8 mass% of SMZnO, as well as the char yield enhanced significantly, which was about 23.5% higher than the neat PA. The peak heat release rate resulted from microscale combustion calorimeter (MCC), by 8 mass% loading of SMZnO, decreased about 56.9% lower than the neat PA.

  17. A novel reduced graphene oxide decorated with halloysite nanotubes (HNTs-d-rGO hybrid composite and its flame-retardant application for polyamide 6

    Directory of Open Access Journals (Sweden)

    M. F. Zhu

    2014-06-01

    Full Text Available The improvement of flame-retardant properties of polyamide 6 (PA6 was achieved by using reduced graphene oxide decorated with halloysite nanotubes (HNTs-d-rGO hybrid composite as the additive in PA6 matrix. The intimate integration of reduced graphene oxide (rGO and halloysite nanotubes (HNTs through a three-step chemical functionalization, enabled the combination of their unique physical and chemical characteristics together. The nanostructure of HNTs-d-rGO was determined by Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS and transmission electron microscopy (TEM. A morphological study revealed that HNTs-d-rGO was dispersed uniformly in PA6 matrix. From the results of cone calorimetry measurements, the fire retardant properties of PA6 were further improved with the addition of HNTs-d-rGO when compared with that of either HNTs, or GO, or a mixture of HNTs and GO (HNTs-m-GO used in PA6 matrix. The results indicate clearly that higher flame-retardant activity of the integrated HNTs-d-rGO nanostructures than that of the simple mixture verifies the importance of the intimate integration between HNTs and rGO, which ascribe to the combination of the stable silica layer created by HNT and the barrier effect of rGO.

  18. Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part I: Effects of Bisphenol A on Freshwater Zooplankton Are Lower in Presence of Polyamide Particles

    Science.gov (United States)

    Rehse, Saskia; Kloas, Werner; Zarfl, Christiane

    2018-01-01

    Microplastics can have direct physical effects on organisms in freshwater systems, and are considered as vectors for absorbed environmental pollutants. It is still under discussion if microplastics are relevant pollutant vectors for uptake into aquatic organisms in comparison to further uptake pathways, e.g., via water or sediment particles. We analyzed how the presence of microplastics (polyamide particles, PA) modifies acute effects of the environmental pollutant bisphenol A (BPA) on freshwater zooplankton (Daphnia magna). Daphnids were exposed to PA particles and BPA alone, before combining them in the next step with one concentration of PA and varying concentrations of BPA. The PA particles themselves did not induce negative effects, while the effects of BPA alone followed a typical dose-dependent manner. Sorption of BPA to PA particles prior to exposure led to a reduction of BPA in the aqueous phase. The combination of BPA and PA led to decreased immobilization, although PA particles loaded with BPA were ingested by the daphnids. Calculations based on physiochemistry and equilibrium assumptions indicated lower BPA body burden of daphnids in the presence of PA particles. These results confirm model-based studies, and show that investigated microplastic concentrations are negligible for the overall pollutant uptake of daphnids with water as additional uptake pathway. PMID:29415519

  19. Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part I: Effects of Bisphenol A on Freshwater Zooplankton Are Lower in Presence of Polyamide Particles

    Directory of Open Access Journals (Sweden)

    Saskia Rehse

    2018-02-01

    Full Text Available Microplastics can have direct physical effects on organisms in freshwater systems, and are considered as vectors for absorbed environmental pollutants. It is still under discussion if microplastics are relevant pollutant vectors for uptake into aquatic organisms in comparison to further uptake pathways, e.g., via water or sediment particles. We analyzed how the presence of microplastics (polyamide particles, PA modifies acute effects of the environmental pollutant bisphenol A (BPA on freshwater zooplankton (Daphnia magna. Daphnids were exposed to PA particles and BPA alone, before combining them in the next step with one concentration of PA and varying concentrations of BPA. The PA particles themselves did not induce negative effects, while the effects of BPA alone followed a typical dose-dependent manner. Sorption of BPA to PA particles prior to exposure led to a reduction of BPA in the aqueous phase. The combination of BPA and PA led to decreased immobilization, although PA particles loaded with BPA were ingested by the daphnids. Calculations based on physiochemistry and equilibrium assumptions indicated lower BPA body burden of daphnids in the presence of PA particles. These results confirm model-based studies, and show that investigated microplastic concentrations are negligible for the overall pollutant uptake of daphnids with water as additional uptake pathway.

  20. Effects of Organomontmorillonite Content on Morphology and Mechanical and Thermal Properties of Poly(2,6-dimethyl-1,4-phenylene oxide/Polyamide-66 Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kunxiao Yang

    2016-01-01

    Full Text Available The nanocomposites consisting of polymer matrix and nanofiller have attracted great attention because of the improved physical properties. In this paper, organomontmorillonite (OMMT was introduced into poly(2,6-dimethyl-1,4-phenylene oxide grafted maleic anhydride (PPO-g-MA compatibilized poly(2,6-dimethyl-1,4-phenylene oxide/polyamide-66 (PPO/PA66 blends by melt extrusion. The morphology of PPO/PA66 nanocomposites with different amounts of OMMT was investigated using transmission electron microscopy (TEM, wide-angle X-ray diffraction (WAXD, and scanning electron microscopy (SEM. The OMMT platelets exhibited an exfoliated structure in the PA66 matrix and an intercalated structure on the surface of PPO domains at low OMMT loading (2 phr. However, the exfoliated platelets in matrix were found to transform into intercalated stacks by adding 6 phr of OMMT. The mechanical properties and thermal stability were significantly improved with the coexistence of exfoliated and intercalated OMMT at low OMMT loading (2–4 phr. The exfoliated OMMT platelets imposed a confinement effect on the macromolecular chains and thereby increased the storage modulus and complex viscosity of nanocomposites.

  1. Study the influence of reacted aliphatic amine series length on its kinetic reaction with dimeric fatty acid C36 and properties of resulted polyamide

    International Nuclear Information System (INIS)

    Al-Mohammad, H.; Falah, A.; Al-Hammoy, M.

    2013-01-01

    Kinetic studies were carried out on the reaction between dimeric fatty acid C 3 6 with 1.3 Diamino propane and 1.4 Diamino butane and 1.6 Diamino hexane and 1.8 Diamino octane in molten phase. The reaction was performed at 145 o C. The polyamidation reaction was found to be on the overall a second order up to 83% conversion for reaction dimeric fatty acid C-36 with 1.3 Diamino propane and 86% conversion for reaction dimeric fatty acid C 3 6 with 1.4 Diamino butane and 87% conversion for reaction dimeric fatty acid C 3 6 with 1.6 Diamino hexane and 1.8 Diamino octane then the reaction order changes to the third order above last conversion. The degree of polymerization,number average molecular weight and weight average molecular weight have been calculated during different times. Their relationships with the times are linear until last conversion. The melting point and thermodynamic constants for melting are determined by use of differential scanning calorimetry DSC. The melting point and thermodynamic constants increase by increasing the length of reacted amine series. (author)

  2. Integrated effect of supramolecular self-assembled sandwich-like melamine cyanurate/MoS{sub 2} hybrid sheets on reducing fire hazards of polyamide 6 composites

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiaming [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Wang, Xin, E-mail: wxcmx@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Cai, Wei; Hong, Ningning [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Liew, Kim Meow [Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Department of Architectural and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2016-12-15

    A novel strategy of using supramolecular self-assembly for preparing sandwich-like melamine cyanurate/MoS{sub 2} sheets as the hybrid flame retardants for polyamide 6 (PA6) is reported for the first time. The introduction of MoS{sub 2} sheets function not only as a template to induce the formation of two-dimensional melamine cyanurate capping layers but also as a synergist to generate integrated flame-retarding effect of hybrid sheets, as well as a high-performance smoke suppressor to reduce fire hazards of PA6 materials. Once incorporating this well-designed structures (4 wt%) into PA6 matrix, there resulted in a remarkable drop (40%) in the peak heat release rate and a 25% reduction in total heat release. Moreover, the smoke production and pyrolysis gaseous products were efficiently suppressed by the addition of sandwich-like hybrid sheets. The integrated functions consisting of inherent flame retarding effect, physical barrier performance and catalytic activity are believed to the crucial guarantee for the reduced fire hazards of PA6 nanocomposites. Furthermore, this novel strategy with facile and scalable features may provide reference for developing various kinds of MoS{sub 2} based hybrid sheets for diverse applications.

  3. The influence of aging process generated by biodiesel in different conditions of time and temperature on the mechanical properties of polyamide 12

    International Nuclear Information System (INIS)

    Nascimento, Roberto A.; Souza, Adriana M.C.

    2015-01-01

    This work aimed to evaluate the influence of aging processes generated by biodiesel, through immersion tests in different times (1000, 3000 and 5000 hours) and temperatures (23 and 100°C), on the mechanical properties of a commercial polyamide 12 used for fuel hoses manufacturing. Specimens were injection molded, aged and further characterized by FTIR, XRD and tensile and impact strength tests. FTIR analysis indicated a possible thermo-oxidative degradation mainly for the aging carried out at 100°C. The XRD spectra indicated an increase in the surface crystallinity of the specimens with increasing aging time for the aging carried out at 100°C. The tensile strength and elastic modulus of PA12 samples aged at 23°C decreased with increasing aging time. For the aging carried out at 100°C, the tensile strength and elastic modulus increased with aging time. The impact strength at -40°C of PA12 presented different behaviors when aged at room temperature and 100°C. (author)

  4. Effect of CO{sub 2}-laser irradiation on properties and performance of thin-film composite polyamide reverse osmosis membrane

    Energy Technology Data Exchange (ETDEWEB)

    Jahangiri, Foad; Mousavi, Seyyed Abbas; Farhadi, Fathollah; Sabzi, Behnam; Chenari, Zeinab [Sharif University of Technology, Tehran (Iran, Islamic Republic of); Vatanpour, Vahid [Kharazmi (Tarbiat Moallem) University, Tehran (Iran, Islamic Republic of)

    2016-03-15

    CO{sub 2}-laser irradiation was used to modify the surface properties of thin-film composite (TFC) polyamide reverse osmosis (RO) membranes. These membranes were first synthesized via interfacial polymerization of m-phenylenediamine (MPD) monomers and trimesoyl chloride (TMC) over porous polysulfone ultrafiltration support, followed by a CO{sub 2}-irradiation. AFM, ATR-FTIR, SEM and contact angle measurements were used to characterize the surface properties of these membranes. The ATR-FTIR results indicated that CO{sub 2}-laser irradiation did not induce any functional groups on the membrane surface. However, it was found that the laser irradiation enhanced the NaCl salt rejection and slightly reduced the permeate flux. Moreover, the maintenance of the flux in modified membranes was much higher than untreated ones. Specially, after 180 min of filtration, the reduction in initial flux for the unmodified membranes was 22%. However, the reduction in initial flux for the modified membranes was less than 5%. Bovine serum albumin (BSA) filtration revealed an improvement in the antifouling properties of the modified membranes. The changes in the membrane surface morphology showed that the roughness of membrane surface is reduced significantly.

  5. Construction of flame retardant coating on polyamide 6.6 via UV grafting of phosphorylated chitosan and sol-gel process of organo-silane.

    Science.gov (United States)

    Kundu, Chanchal Kumar; Wang, Xin; Hou, Yanbei; Hu, Yuan

    2018-02-01

    Phosphorylated chitosan (PCS) was synthesized and grafted onto the surface of polyamide 6.6 (PA 6.6) fabrics via UV-induced grafting polymerization in order to improve the flame retardant properties. Subsequently, PCS grafted PA 6.6 fabrics were modified by (3-aminopropyl) triethoxysilane (APTES) through sol-gel process in order to form a cross-linking coating. The results obtained from the vertical burning test indicated that only the PCS grafted and simultaneously sol-gel treated fabrics could stop the melt dripping. A maximum reduction (30%) in the peak heat release rate was achieved for the PA6.6-PCS-4W-SG fabric sample. The optimal flame retardant effect was achieved for the PA6.6 fabrics treated by PCS and APTES simultaneously, which was attributed to the joint effect of thermal shielding exerted by the silica and char-forming effect derived from PCS. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. New polyvinyl chloride (PVC) nanocomposite consisting of aromatic polyamide and chitosan modified ZnO nanoparticles with enhanced thermal stability, low heat release rate and improved mechanical properties

    Science.gov (United States)

    Hajibeygi, Mohsen; Maleki, Mahdiye; Shabanian, Meisam; Ducos, Franck; Vahabi, Henri

    2018-05-01

    New ternary nanocomposite systems containing polylvinyl chloride (PVC), chitosan modified ZnO (CMZN) nanoparticles and new synthesized polyamide (PA) were designed and prepared by solution casting method. As a potential reinforcement, CMZN was used in PVC system combined with and without PA. Morphology, mechanical, thermal and combustion properties of the all PVC systems were studied. In the presence of the CMZN, PA showed a synergistic effect on improvement of the all investigated properties of PVC. The 5 mass% loss temperature (T5) was increased from 195 °C to 243 °C in PVC/CMZN-PA nanocomposite containing 1 mass% of each PA and CMZN (PZP 2). The peak of heat release rate was decreased from 131 W/g for PVC to 104 W/g for PVC/CMZN-PA nanocomposite containing 3 mass% of each PA and CMZN (PZP 6). According to the tensile tests, compared to the neat PVC, the tensile strength was increased from 35.4 to 53.4 MPa for PZP 6.

  7. Performance Enhancement of Silicon Alloy-Based Anodes Using Thermally Treated Poly(amide imide) as a Polymer Binder for High Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Yang, Hwi Soo; Kim, Sang-Hyung; Kannan, Aravindaraj G; Kim, Seon Kyung; Park, Cheolho; Kim, Dong-Won

    2016-04-05

    The development of silicon-based anodes with high capacity and good cycling stability for next-generation lithium-ion batteries is a very challenging task due to the large volume changes in the electrodes during repeated cycling, which results in capacity fading. In this work, we synthesized silicon alloy as an active anode material, which was composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. Poly(amide imide)s, (PAI)s, with different thermal treatments were used as polymer binders in the silicon alloy-based electrodes. A systematic study demonstrated that the thermal treatment of the silicon alloy electrodes at high temperature made the electrodes mechanically strong and remarkably enhanced the cycling stability compared to electrodes without thermal treatment. The silicon alloy electrode thermally treated at 400 °C initially delivered a discharge capacity of 1084 mAh g(-1) with good capacity retention and high Coulombic efficiency. This superior cycling performance was attributed to the strong adhesion of the PAI binder resulting from enhanced secondary interactions, which maintained good electrical contacts between the active materials, electronic conductors, and current collector during cycling. These findings are supported by results from X-ray photoelectron spectroscopy, scanning electron microscopy, and a surface and interfacial cutting analysis system.

  8. Evaluation of Uniformity and Glare Improvement with Low Energy Efficiency Losses in Street Lighting LED Luminaires Using Laser-Sintered Polyamide-Based Diffuse Covers

    Directory of Open Access Journals (Sweden)

    Alfonso Gago-Calderón

    2018-04-01

    Full Text Available Energy saving in street lighting is garnering more interest and has become a priority in municipal management. Therefore, LED luminaires are gradually becoming prevalent in our cities. Beyond their energy/economic saving potential, quality in public lighting installations concerns aspects such as uniformity and glare which must be maintained if not improved in any installation renewal project using this technology. The high light intensity generated in a discrete point in LED packages and its directional nature result in significant deficiencies in these last two parameters. To soften these effects, translucent covers are being used as one of the most common solutions with the drawback of significant light intensity losses. The objective of this paper is to evaluate the behavior of LED luminaire’s polyamide-based optical covers manufactured with a laser-sintered process. These are designed to improve glare and uniformity output, to minimize light output reductions, and to be industrially manufactured with no increment of cost for their lighting equipment compared to conventional transparent polycarbonate solutions. A laboratory and field lighting test study has been applied to different covers with the same LED lamp and luminaire to compare the performance of three different solutions built with different polymeric materials and with different light transmission surface textures. The photometric results have been observed and discussed to demonstrate the ability to significantly improve the lighting performance of LED luminaires—illuminance and uniformity levels and discomfort and disability glare indexes— using an improved optic cover.

  9. In vitro and in vivo evaluations of nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF as a novel bioactive bone screw.

    Directory of Open Access Journals (Sweden)

    Bao Su

    Full Text Available In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications.

  10. Increasing the Thermal Conductivity of Graphene-Polyamide-6,6 Nanocomposites by Surface-Grafted Polymer Chains: Calculation with Molecular Dynamics and Effective-Medium Approximation.

    Science.gov (United States)

    Gao, Yangyang; Müller-Plathe, Florian

    2016-02-25

    By employing reverse nonequilibrium molecular dynamics simulations in a full atomistic resolution, the effect of surface-grafted chains on the thermal conductivity of graphene-polyamide-6.6 (PA) nanocomposites has been investigated. The interfacial thermal conductivity perpendicular to the graphene plane is proportional to the grafting density, while it first increases and then saturates with the grafting length. Meanwhile, the intrinsic in-plane thermal conductivity of graphene drops sharply as the grafting density increases. The maximum overall thermal conductivity of nanocomposites appears at an intermediate grafting density because of these two competing effects. The thermal conductivity of the composite parallel to the graphene plane increases with the grafting density and grafting length which is attributed to better interfacial coupling between graphene and PA. There exists an optimal balance between grafting density and grafting length to obtain the highest interfacial and parallel thermal conductivity. Two empirical formulas are suggested, which quantitatively account for the effects of grafting length and density on the interfacial and parallel thermal conductivity. Combined with effective medium approximation, for ungrafted graphene in random orientation, the model overestimates the thermal conductivity at low graphene volume fraction (f 10%). For unoriented grafted graphene, the model matches the experimental results well. In short, this work provides some valuable guides to obtain the nanocomposites with high thermal conductivity by grafting chain on the surface of graphene.

  11. Dispersion toughened silicon carbon ceramics

    Science.gov (United States)

    Wei, G.C.

    1984-01-01

    Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

  12. Transformation-Toughened Silicon Nitride

    Science.gov (United States)

    1988-08-01

    of pores, could be eliminated by iso - statically pressing the green flexure test bars after the burnout operation and before the sintering...Company Fourth and Canal Streets PO Box 27003 Richmond, VA 23261 Stephen C. Danforth Rutgers University Post Office Box 909 Bowser Road

  13. Influence of non-covalent modification of multiwalled carbon nanotubes on the crystallization behaviour of binary blends of polypropylene and polyamide 6.

    Science.gov (United States)

    Mukhopadhyay, Nabaneeta; Panwar, Ajay S; Kumar, Gulshan; Samajdar, I; Bhattacharyya, Arup R

    2015-02-14

    Blends of polypropylene (PP) and polyamide 6 (PA6) with multiwalled carbon nanotubes (MWNTs) were prepared using different processing strategies in a twin-screw micro-compounder. The effect of MWNTs on the crystallization behaviour of the PP phase and the PA6 phase of the blend has been investigated through non-isothermal crystallization studies by differential scanning calorimetric analysis. Furthermore, the effect of the addition of the compatibilizer (PP-g-MA) and the modification of MWNTs (m-MWNTs) with a non-covalent organic modifier (Li-salt of 6 amino hexanoic acid, Li-AHA) has also been studied in context to the crystallization behaviour of the PP and PA6 phase in the blend. The crystallization studies have indicated a significant increase in bulk crystallization temperature of the PP phase in the blend in the presence of MWNTs. Moreover, the formation of 'trans-lamellar crystalline' structure consisting of PA6 'trans-crystalline lamellae' on MWNTs surface was facilitated in the case of blends prepared via 'protocol 2' as compared to the corresponding blends prepared via 'protocol 1'. Wide angle X-ray diffraction analysis has showed the existence of a β-polymorph of the PP phase due to incorporation of the PA6 phase in the blend. Addition of MWNTs in the blends has facilitated further β-crystalline structure formation of the PP phase. In the presence of m-MWNTs, a higher β-fraction was observed in the PP phase as compared to the blend with pristine MWNTs. Addition of PP-g-MA has suppressed the β-phase formation in the PP phase in the blend. X-ray bulk texture analysis revealed that incorporation of PA6 as well as pristine/modified MWNTs has influenced the extent of orientation of the PP chains towards specific crystalline planes in various blend compositions of PP and PA6.

  14. Morphological studies on block copolymer modified PA 6 blends

    Energy Technology Data Exchange (ETDEWEB)

    Poindl, M., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de; Bonten, C., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de [Institut für Kunststofftechnik, University of Stuttgart (Germany)

    2014-05-15

    Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymer was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.

  15. Polietileno de Alta Densidade Tenacificado com Elastômero Metalocênico: 1. Propriedades Mecânicas e Características Morfológicas Rubber Toughened High Density Polyethylene: 1. Mechanical Properties and Morphological Characteristics

    Directory of Open Access Journals (Sweden)

    Maria José O. C. Guimarães

    2002-01-01

    Full Text Available Neste trabalho foram estudadas as propriedades mecânicas e morfológicas de polietileno de alta densidade (HDPE tenacificado com dois tipos de elastômeros metalocênicos à base de etileno/1- octeno (EOC. Esses elastômeros são polímeros comerciais com diferenças quanto ao peso molecular, índice de fluidez e índice Dow de reologia (DRI. Misturas físicas de HDPE e EOC foram processadas em extrusora monorosca Wortex (L/D=32, à 230°C e 50 rpm, utilizando percentagem mássica do EOC de 5% a 80%. Foi observado um efeito sinergístico nas propriedades tênseis e características de supertenacificação para materiais contendo proporções do EOC maiores do que 5%. Cavitação, deformação plástica e cavitação fibrilada foram observados nos processos de deformação. Materiais contendo até 50% do EOC apresentaram morfologias dispersas com domínios elastoméricos esféricos, distribuídos uniformemente e com tamanho médio de partícula na faixa de 0,30 a 0,45 µm. A tenacificação de HDPE com os elastômeros etilênicos produziu materiais com boas propriedades e compatibilização tecnológica devido à existência de baixa tensão interfacial entre esses polímeros.The mechanical and morphological properties of high density polyethylene (HDPE toughened with two different grades of metallocene elastomers based on ethylene/1- octene (EOC were studied. These elastomers were commercial polymers differing in molecular weight, melt flow index and Dow rheology index (DRI. Blends were processed in a Wortex single screw extruder (L/D=32, at 230°C and 50 rpm, using mass fraction weight percent of EOC in the range from 5% to 80%. A synergistic effect on the tensile properties and supertough behavior for blends with EOC concentrations higher than 5% was observed. Cavitation, plastic deformation and fibrillized cavitation were observed in the deformation processes. Materials containing up to 50% of EOC exhibited dispersed morphologies with EOC

  16. In vitro and in vivo biocompatibility and osteogenesis of graphene-reinforced nanohydroxyapatite polyamide66 ternary biocomposite as orthopedic implant material

    Directory of Open Access Journals (Sweden)

    Zhang S

    2016-07-01

    Full Text Available Shiyang Zhang,1 Qiming Yang,1 Weikang Zhao,1 Bo Qiao,1 Hongwang Cui,1 Jianjun Fan,2 Hong Li,3 Xiaolin Tu,4 Dianming Jiang1 1Department of Orthopedics, The First Affiliated Hospital of Chongqing Medical University, 2Molecular Medicine and Cancer Research Centre, Chongqing Medical University, Chongqing, 3College of Physical Science and Technology, Sichuan University, Chengdu, 4Institutes of Life Sciences, Chongqing Medical University, Chongqing, People’s Republic of China Abstract: Graphene and its derivatives have been receiving increasing attention regarding their application in bone tissue engineering because of their excellent characteristics, such as a vast specific surface area and excellent mechanical properties. In this study, graphene-reinforced nanohydroxyapatite/polyamide66 (nHA/PA66 bone screws were prepared. The results of scanning electron microscopy observation and X-ray diffraction data showed that both graphene and nHA had good dispersion in the PA66 matrix. In addition, the tensile strength and elastic modulus of the composites were significantly improved by 49.14% and 21.2%, respectively. The murine bone marrow mesenchymal stem cell line C3H10T1/2 exhibited better adhesion and proliferation in graphene reinforced nHA/PA66 composite material compared to the nHA/PA66 composites. The cells developed more pseudopods, with greater cell density and a more distinguishable cytoskeletal structure. These results were confirmed by fluorescent staining and cell viability assays. After C3H10T1/2 cells were cultured in osteogenic differentiation medium for 7 and 14 days, the bone differentiation-related gene expression, alkaline phosphatase, and osteocalcin were significantly increased in the cells cocultured with graphene reinforced nHA/PA66. This result demonstrated the bone-inducing characteristics of this composite material, a finding that was further supported by alizarin red staining results. In addition, graphene reinforced nHA/PA66

  17. Diagnostics of N2 Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    Science.gov (United States)

    Saloum, S.; Naddaf, M.; Alkhaled, B.

    2008-02-01

    N2-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 <= x <= 80), at a constant applied RF power of 300 W. N2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I_N/I_{N_2} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N2, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N_{2}^{+} density varies between 5 × 109 and 1.4 × 1010 cm-3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2Σ+-X 2Σ+) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

  18. Diagnostics of N2-Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    International Nuclear Information System (INIS)

    Saloum, S; Naddaf, M; Alkhaled, B

    2008-01-01

    N 2 -x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 ≤ x ≤ 80), at a constant applied RF power of 300 W. N 2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I N /I N 2 of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N 2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N 2 , with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N 2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N 2 + density varies between 5 x 10 9 and 1.4 x 10 10 cm -3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2 Σ + -X 2 Σ + ) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased

  19. Diagnostics of N{sub 2}-Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    Energy Technology Data Exchange (ETDEWEB)

    Saloum, S; Naddaf, M; Alkhaled, B [Atomic Energy Commission of Syria (AECS), Physics Department, PO Box 6091, Damascus (Syrian Arab Republic)], E-mail: scientific@aec.org.sy

    2008-02-21

    N{sub 2}-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 {<=} x {<=} 80), at a constant applied RF power of 300 W. N{sub 2} dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I{sub N}/I{sub N{sub 2}} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N{sub 2} second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N{sub 2}, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N{sub 2} second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N{sub 2}{sup +} density varies between 5 x 10{sup 9} and 1.4 x 10{sup 10} cm{sup -3} and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

  20. Exploration of polyamide structure-property relationships by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Barrère, Caroline; Rejaibi, Majed; Curat, Aurélien; Hubert-Roux, Marie; Lavanant, Hélène; Afonso, Carlos; Kebir, Nasreddine; Desilles, Nicolas; Lecamp, Laurence; Burel, Fabrice; Loutelier-Bourhis, Corinne

    2014-08-15

    Polyamides (PA) are among the most used classes of polymers because of their attractive properties. Depending on the nature and proportion of the co-monomers used for their synthesis, they can exhibit a very large range of melting temperatures (Tm ). This study aims at the correlation of data from mass spectrometry (MS) with differential scanning calorimetry (DSC) and X-ray diffraction analyses to relate molecular structure to physical properties such as melting temperature, enthalpy change and crystallinity rate. Six different PA copolymers with molecular weights around 3500 g mol(-1) were synthesized with varying proportions of different co-monomers (amino-acid AB/di-amine AA/di-acid BB). Their melting temperature, enthalpy change and crystallinity rate were measured by DSC and X-ray diffraction. Their structural characterization was carried out by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Because of the poor solubility of PA, a solvent-free sample preparation strategy was used with 2,5-dihydroxybenzoic acid (2,5-DHB) as the matrix and sodium iodide as the cationizing agent. The different proportions of the repeating unit types led to the formation of PA with melting temperatures ranging from 115°C to 185°C. The structural characterization of these samples by MALDI-TOF-MS revealed a collection of different ion distributions with different sequences of repeating units (AA, BB; AB/AA, BB and AB) in different proportions according to the mixture of monomers used in the synthesis. The relative intensities of these ion distributions were related to sample complexity and structure. They were correlated to DSC and X-ray results, to explain the observed physical properties. The structural information obtained by MALDI-TOF-MS provided a better understanding of the variation of the PA melting temperature and established a structure-properties relationship. This work will allow future PA designs to be monitored. Copyright

  1. Surface treatment of poly(ethylene terephthalate) by gamma-ray induced graft copolymerization of methyl acrylate and its toughening effect on poly(ethylene terephthalate)/elastomer blend

    International Nuclear Information System (INIS)

    Ma, Liang; Wang, Mozhen; Ge, Xuewu

    2013-01-01

    To improve the compatibility between ethylene-methyl acrylate-glycidyl methacrylate random terpolymer (E-MA-GMA) elastomer and poly(ethylene terephthalate) (PET), thereby enhance the toughening effect of E-MA-GMA on PET, γ-radiation-induced graft copolymerization technique was used to graft methyl acrylate (MA) monomer onto PET. The produced PET-g-PMA copolymer can be used as a self-compatibilizer in PET/E-MA-GMA blend since the copolymer contains the same segments, respectively, with PET and E-MA-GMA. The impact strength of PET/E-MA-GMA blend increased nearly by 30% in the presence of less than 0.1 wt% PET-g-PMA compared with that of the neat PET/elastomer blend, without loss of the tensile strength of the blends. This work proposed a potential application of radiation-induced grafting copolymerization technique on the in-situ compatibilization of PET/elastomer blends so as to improve the integral mechanical properties of PET based engineering plastic. - Highlights: • PMA was grafted onto PET resins by γ-ray radiation-induced copolymerization. • The obtained PET-g-PMA can improve the compatibility between PET and E-MA-GMA. • A small amount of PET-g-PMA can enhance the impact strength of PET/E-MA-GMA blend

  2. Influence of heat treatments upon the mechanical properties and in vitro bioactivity of ZrO2-toughened MgO-CaO-SiO2-P2O5-CaF2 glass-ceramics.

    Science.gov (United States)

    Li, Huan-Cai; Wang, Dian-Gang; Meng, Xiang-Guo; Chen, Chuan-Zhong

    2014-09-01

    Zirconia-toughened MgO-CaO-SiO2-P2O5-CaF2 glass-ceramics are prepared using sintering techniques, and a series of heat treatment procedures are designed to obtain a glass-ceramic with improved properties. The crystallization behavior, phase composition, and morphology of the glass-ceramics are characterized. The bending strength, elastic modulus, fracture toughness, and microhardness of the glass-ceramics are investigated, and the effect mechanism of heat treatments upon the mechanical properties is discussed. The bioactivity of glass-ceramics is then evaluated using the in vitro simulated body fluid (SBF) soaking test, and the mechanism whereby apatite forms on the glass-ceramic surfaces in the SBF solution is discussed. The results indicate that the main crystal phase of the G-24 sample undergoing two heat treatment procedures is Ca5(PO4)3F (fluorapatite), and those of the G-2444 sample undergoing four heat treatment procedures are Ca5(PO4)3F and β-CaSiO3 (β-wollastonite). The heat treatment procedures are found to greatly influence the mechanical properties of the glass-ceramic, and an apatite layer is induced on the glass-ceramic surface after soaking in the SBF solution.

  3. Improved dielectric constant and breakdown strength of γ-phase dominant super toughened polyvinylidene fluoride/TiO2 nanocomposite film: an excellent material for energy storage applications and piezoelectric throughput

    Science.gov (United States)

    Mehebub Alam, Md; Ghosh, Sujoy Kumar; Sarkar, Debabrata; Sen, Shrabanee; Mandal, Dipankar

    2017-01-01

    Titanium dioxide (TiO2) nanoparticles (NPs) embedded γ-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m-1). It also exhibits a high energy density of 4 J cm-3 which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.

  4. Analysis of linear and cyclic oligomers in polyamide-6 without sample preparation by liquid chromatography using the sandwich injection method. II. Methods of detection and quantification and overall long-term performance.

    Science.gov (United States)

    Mengerink, Y; Peters, R; Kerkhoff, M; Hellenbrand, J; Omloo, H; Andrien, J; Vestjens, M; van der Wal, S

    2000-05-05

    By separating the first six linear and cyclic oligomers of polyamide-6 on a reversed-phase high-performance liquid chromatographic system after sandwich injection, quantitative determination of these oligomers becomes feasible. Low-wavelength UV detection of the different oligomers and selective post-column reaction detection of the linear oligomers with o-phthalic dicarboxaldehyde (OPA) and 3-mercaptopropionic acid (3-MPA) are discussed. A general methodology for quantification of oligomers in polymers was developed. It is demonstrated that the empirically determined group-equivalent absorption coefficients and quench factors are a convenient way of quantifying linear and cyclic oligomers of nylon-6. The overall long-term performance of the method was studied by monitoring a reference sample and the calibration factors of the linear and cyclic oligomers.

  5. Kinetics of reaction dimer fatty acid C_36 with 1,9 diamino nonane and determination of thermodynamic constants by use of thermogravimetric analysis tga, and rheological constants for the resulted polyamide

    International Nuclear Information System (INIS)

    Mohammad, H.; Falah, Al; Hammoy, M.

    2014-01-01

    Study the kinetics degradation of poly (dimeric acid C_36 with 1.9 – diamino nonane) was carried out by thermal analysis (TGA), and thermodynamic and equilibrium constants have been defined, moreover, study the kinetics of reaction between 1.9 – diamino nonane and dimer fatty acid C_36 was carried out in molten state, the reaction was performed at 160°, the acid value, and percentage of carboxylic functions of the product were determined. The polyamidation reaction was found to be of overall second order until conversion of 97% at 160°, then the order of reaction changes. The degree of dispersion, number molecular weight, weight molecular weight ,and viscosity molecular weight have been calculated during different times.The relationships between degree of dispersion, number Average molecular weight, weight average molecular weight, and viscosity molecular weight with time is linear at160°. Spectroscopy studies were carried out by infra-red and ultraviolet spectroscopy (author).

  6. Evaluation of the permeability of microporous membranes polyamide 6 / clay bentonite for water-oil separation; Avaliacao da permeabilidade de membranas microporosas de poliamida 6/argila bentonitica para separacao agua-oleo

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, P.S.S.; Medeiros, K.M.; Araujo, E.M.; Lira, H.L., E-mail: keilamm@ig.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2014-07-01

    The petroleum refining industries have faced major problems in relation to the treatment of their effluents before disposal into the environment. Among the conventional technologies treatment of these effluents, the process of oil-water separation by means of membranes has been extensively used, for having enormous potentiality. Therefore, in this study, hybrid membranes of polyamide 6/ bentonite clay were produced by the technique of phase inversion and by precipitation of the solution from the nanocomposites obtained by melt intercalation. The clay was organically modified with the quaternary ammonium salt (Cetremide®). The nanocomposites were obtained from (PA6) with untreated (AST) and treated clay (ACT), which were subsequently characterized by X-ray diffraction (XRD). Already membranes were characterized by XRD, scanning electron microscopy (SEM) and flow measurements. From the XRD results, it was observed an exfoliated and/or partially exfoliated structure for the nanocomposites and for the membranes. From SEM images it was observed that the presence of AST and ACT clays in the polymeric matrix caused changes in membrane morphology and pore formation. The flow with distilled water in the membranes showed a decrease initially and then followed by stability. All membranes tested in the process of separating emulsions of oil in water, particularly those of nanocomposites obtained a significant reduction of oil concentration in the permeate, thus showing that these membranes have a great potential to be applied to the water-oil separation. (author)

  7. Microporous membranes from polyamide 6/national clay nanocomposites - Part 2: microstructural and permeability evaluation; Obtencao de membranas microporosas a partir de nanocompositos de polimida 6/argila nacional - Parte 2: avaliacao microestrutural e de permeabilidade das membranas obtidas

    Energy Technology Data Exchange (ETDEWEB)

    Leite, Amanda M.D.; Araujo, Edcleide M.; Lira, Helio de L.; Paz, Rene Anisio da; Medeiros, Vanessa da Nobrega, E-mail: amandamelissa.lins@yahoo.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

    2014-06-01

    Organic/inorganic hybrid membranes of polyamide 6 and mineral clay containing layers of silicate were prepared and compared to those of the pure polymer. Use was made of an as-received sodium clay from industry and another organophilized with ammonium quaternary salts (Dodigen and Cetremide). The salts make the clays surface hydrophobic and improve their incorporation into the polymer matrix in the molten state. Membranes were prepared with these nanocomposites using the immersion-precipitation technique with formic acid as a solvent, and precipitation in a water bath as non-solvent. The acid concentration in the solution containing the polymer and the hybrids was varied to study its influence in morphology and permeability of the membranes. An asymmetric morphology consisting of a filter skin and a porous support was observed, with pores both on the surface and in the cross section being affected by the different salts. This asymmetric morphology was also affected significantly by the acid concentration, with thicker filter skins for higher concentrations. The acid concentration affected the pores size and their distribution. The clay particles probably acted as a barrier to the flow. The permeating flux for the two acid concentrations varied as a function of the distinct morphologies. (author)

  8. Carbon nanotubes: do they toughen brittle matrices?

    Czech Academy of Sciences Publication Activity Database

    Chao, J.; Inam, F.; Reece, M.J.; Chlup, Zdeněk; Dlouhý, Ivo; Shaffer, M.S.P.; Boccaccini, A. R.

    2011-01-01

    Roč. 46, č. 14 (2011), s. 4770-4779 ISSN 0022-2461 R&D Projects: GA ČR GA101/09/1821 Institutional research plan: CEZ:AV0Z20410507 Keywords : fracture toughness * carbon nanotube * silica glass Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.015, year: 2011 http://www.springerlink.com/content/74106l0458326n91/

  9. A comparison of the performance of aromatic polyamide and cellulose acetate reverse osmosis membrane on the regeneration of secondary effluents; Comparacion del funcionamiento de membranas de osmosis inversa de poliamida aromatica y acetato de celulosa en la regeneracion de efluentes secundarios

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Ramirez, J. A.; Carrasco Vega, M.; Sales Marquez, D.; Quiroga Alonso, J. M.

    2002-07-01

    The application of reverse osmosis in regenerating waste waters has aroused a great deal of interest, although relatively few experiments using this technique have so far been carried out in Spain. In 1994, an experimental pilot plant was built at the La Barrosa waste water treatment plant in Chiclana de la Frontera in the province of Cadiz. This pilot plant with a capacity of 100 m''3/day, was equipped with various advanced treatments, most notably reverse osmosis, for treating urban waste waters for re-use. Since this pilot plant was built, various experiments have been carried out employing cellulose acetate (Hydranautics) and different types of Spanish-made aromatic polyamide membranes (Pridesa). Each type of membrane proposed different operating characteristics and feed-water requirements making each one suitable for a particular purpose. In this study, the secondary effluents was subjected to different kinds of treatment-called intense treatment, moderate treatment and minimum treatment-before reaching the reverse osmosis unit, which influenced the conditions in which the membranes operated. Following each type of treatment, the waters entering and leaving the installation were analysed to evaluate the quality of the final effluent and the effectiveness of the treatment carried out. The quality was extremely good in all the permeate samples analysed, almost irrespective of the type of treatment applied. It was also found that the cellulose acetate membranes tended to become less dirty than the aromatic polyamide membranes,due to their surface morphology. Nevertheless, the polyamide membranes have various advantages allowing them to be used in a wide range of applications at a lower energy cost. (Author) 8 refs.

  10. Blendas de poliamida 6/elastômero: propriedades e influência da adição de agente compatibilizante Polyamide 6/elastomer blends: properties and compatibilizer influence

    Directory of Open Access Journals (Sweden)

    Guilherme M. O. Barra

    2003-06-01

    Full Text Available Neste trabalho foram estudadas as propriedades micro e macroscópicas de misturas físicas binárias de poliamida 6 [PA6] com copolímero poli(etileno-co-propileno-co-dieno [EPDM] e em presença de pequenas quantidades de EPDM ou EPM enxertados com anidrido maleico, atuando como agentes compatibilizantes. Os componentes puros (poliamida 6 e EPDM e as blendas poliméricas em diferentes composições foram analisados por calorimetria diferencial de varredura (DSC e espectroscopia de infravermelho (FTIR. Os resultados indicaram a imiscibilidade dos componentes da mistura em toda a faixa de composição estudada. A utilização das técnicas de análise elementar, microscopia eletrônica de varredura e propriedades mecânicas permitiu avaliar a homogeneidade da mistura, a redução do tamanho dos domínios do elastômero e o aumento da força de impacto da matriz de PA6 com a adição do agente compatibilizante à mistura binária de PA6/EPDM.This study describes the micro- and macroscopic properties of polyamide 6 (PA6 and ethylene /propylene/diene copolymer (EPDM blends, and the effects from small quantities of EPDM or EPM grafted with maleic anhydride in this polymer mixture. The components and polymer blends at different compositions were analyzed by differential scanning calorimeter (DSC and infrared spectroscopy (FTIR. The results suggest immiscible mixture in all ranges of the blend's compositions. Scanning electron microscopy (SEM micrographs of the blends indicated that the size of rubber aggregates decreases as the functionalized elastomer (EPDM-g-MA or EPM-g-MA is added to the PA6/EPDM mixture, and the impact strength of the PA6 matrix increases significantly.

  11. Mistura reativa de poliamida 6 e policarbonato: reatividade do copolímero formado "in situ" Polyamide 6 and polycarbonate reactive blends: reactivity of the copolymer formed "in situ"

    Directory of Open Access Journals (Sweden)

    Dilma A. Costa

    2004-01-01

    Full Text Available As misturas físicas de poliamida 6 (PA6 e policarbonato (PC processadas a 240 ºC, durante 10, 30 e 60 minutos formam um copolímero de PA6-PC. A alta temperatura e o longo tempo de processamento podem causar modificações nas propriedades dessas misturas e degradar o copolímero, originando grupos isocianato e subseqüentemente CO2 e grupos NH2 terminais. A quantidade de copolímero PA6-PC formado durante o processo de mistura é maior com o aumento da proporção de PC na mistura. As ligações uretânicas de polímeros termoplásticos exibem mais baixas estabilidades térmica e oxidativa, resultando no aumento da concentração de grupos terminais NH2. A reatividade dessas misturas foi investigada através do torque durante o processo de mistura, da titulação potenciométrica dos grupos NH2 terminais e por microscopia eletrônica de varredura.Polyamide 6 (PA6 and polycarbonate (PC blends processed at 240 °C, during 10, 30 and 60 minutes produced a copolymer of PA6-PC. The high temperature and long processing time can cause modifications on the properties of these blends and degradation of the copolymer. It can also form isocyanate groups and subsequently CO2 and NH2 "end groups". The amount of PA6-PC copolymer formed during the blending process was found to increase when the PC content is increased. The thermoplastic urethanes normally exhibit smaller thermal and oxidative stability, resulting in an increase in the concentration of NH2 terminal groups. The reactivity of the blends was investigated by monitoring the torque during the blending, potentiometer titration of NH2 terminal groups and scanning electronic microscopy (SEM.

  12. Caracterização morfológica de nanomembranas de poliamida-66 dopadas com grafeno obtidas por electrospinning Morphological characterization of polyamide-66 nanomembranes with graphene obtained by electrospinning

    Directory of Open Access Journals (Sweden)

    José de Ávila Júnior

    2013-01-01

    Full Text Available Neste estudo, investigou-se a síntese de nanomembranas por eletrofiação (electrospinning. A poliamida-66 (PA-66 foi usada para estudar a influência dos parâmetros operacionais (concentração do polímero, diferença de potencial elétrico aplicada, vazão da solução, distância entre ponta da agulha e o coletor na morfologia das nanofibras. Também foi estudado o efeito da adição de nanofolhas de grafeno na morfologia das nanofibras. Os resultados demonstraram que o diâmetro médio das nanofibras é diretamente proporcional à vazão, à concentração do polímero e à diferença de potencial elétrico aplicada. A adição de nanopartículas de base carbono fez com que o diâmetro médio das nanofibras aumentasse. Os diâmetros médios para as concentrações de grafeno de 0%, 1%, e 2% variaram de 57 nm (0% até 141 nm (2%. No entanto, é importante salientar que os diâmetros médios das nanofibras obtidas estão 37% menores que aqueles reportados na literatura.This paper reports on the synthesis of polymeric nanomembranes produced by electrospinning. Polyamide-66 (PA-66 was used for studying the influence of fabrication parameters (polymer concentration, applied tension, solution flow rate, gap between needle and target on the morphology of the nanofibers. Also investigated was the effect from adding graphene into the nanofiber. The average diameter was directly proportional to polymeric concentration, flow rate, and applied tension. The addition of graphene led to an increase in the average diameter, which ranged from 57 nm for the fibers in absence of graphene to 141 nm for a 2 wt% of graphene added. It should be stressed, however, that the average diameters were 37% smaller than the values reported in the literature.

  13. Caracterização morfológica de nanomembranas de poliamida-66 dopadas com grafeno obtidas por electrospinning Morphological characterization of polyamide-66 nanomembranes with graphene obtained by electrospinning

    Directory of Open Access Journals (Sweden)

    José de Ávila Júnior

    2012-01-01

    Full Text Available Neste estudo, investigou-se a síntese de nanomembranas por eletrofiação (electrospinning. A poliamida-66 (PA-66 foi usada para estudar a influência dos parâmetros operacionais (concentração do polímero, diferença de potencial elétrico aplicada, vazão da solução, distância entre ponta da agulha e o coletor na morfologia das nanofibras. Também foi estudado o efeito da adição de nanofolhas de grafeno na morfologia das nanofibras. Os resultados demonstraram que o diâmetro médio das nanofibras é diretamente proporcional à vazão, à concentração do polímero e à diferença de potencial elétrico aplicada. A adição de nanopartículas de base carbono fez com que o diâmetro médio das nanofibras aumentasse. Os diâmetros médios para as concentrações de grafeno de 0%, 1%, e 2% variaram de 57 nm (0% até 141 nm (2%. No entanto, é importante salientar que os diâmetros médios das nanofibras obtidas estão 37% menores que aqueles reportados na literatura.This paper reports on the synthesis of polymeric nanomembranes produced by electrospinning. Polyamide-66 (PA-66 was used for studying the influence of fabrication parameters (polymer concentration, applied tension, solution flow rate, gap between needle and target on the morphology of the nanofibers. Also investigated was the effect from adding graphene into the nanofiber. The average diameter was directly proportional to polymeric concentration, flow rate, and applied tension. The addition of graphene led to an increase in the average diameter, which ranged from 57 nm for the fibers in absence of graphene to 141 nm for a 2 wt% of graphene added. It should be stressed, however, that the average diameters were 37% smaller than the values reported in the literature.

  14. Influence of the clay content and drying of successive no solvents change in the morphology of polyamide 6 / clay membranes; Influencia do teor de argila e da secagem por troca sucessiva de nao solventes na morfologia das membranas de poliamida 6 / argila

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, C.H.; Ferreira, R.S.B.; Bezerra, E.B.; Leite, A.M.D.; Araujo, E.D.; Lira, H.L., E-mail: caio.henrique7@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2014-07-01

    Membranes of polyamide 6/clay nanocomposites with different contents (1 and 3%) of Brazilian bentonite clay using the technique of phase inversion was obtained. The nanocomposites were obtained in a co-rotating twin screw extruder, by the melt intercalation method and were characterized by x-ray diffraction (XRD), which showed possibly an exfoliated and / or partially exfoliated structure was obtained. The membranes were dried at room temperature and also by successive exchange of non-solvents, to prevent collapse the pores using ethanol and n-hexane as a non-solvent. From the photomicrographs of top surface by scanning electron microscopy (SEM) showed to morphology change in the membranes from the presence of different clay contents as well as drying the same by successive exchange of non-solvents, obtaining membranes with larger amount of pores uniformly distributed. (author)

  15. Synthesis and characterization of hybrid organic-inorganic materials of polyamide-imide (PAI) and copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES); Sintese e caracterizacao de materiais hibridos organico-inorganicos de poliamida-imida e copolisilsesquioxanos de 3-aminopropiltrietoxissilano e feniltrietoxissilano

    Energy Technology Data Exchange (ETDEWEB)

    Demarchi, A.A., E-mail: aa_demarchi@terra.com.b [WEG Equipamentos Eletricos S.A., Jaragua do Sul, SC (Brazil). Dept. de P e D do Produto; Pezzin, S H [Universidade do Estado de Santa Catarina (UDESC), SC (Brazil). Centro de Ciencias Tecnologicas

    2010-07-01

    In this work, organic-inorganic hybrids were obtained by adding copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES), prepared by sol-gel, to the polyamide-imide (PAI). The synthesis of PAI oligomer from trimellitic anhydride (TMA) and 4,4-diphenyl-methane diisocyanate (MDI), was monitored by FTIR, noting that two steps of 80 deg C and 120 deg C for 2 h each are sufficient to obtain it. PAI-copolysilsesquioxanes hybrids were characterized by FTIR, viscometry, thermogravimetry, NMR and microscopy. The spectrum of the PAI and PAI-hybrid copolysilsesquioxanes show the formation of amide and imide. Copolysilsesquioxanes with high levels of APES increased the viscosity and generated the PAI oligomer gelatinization, hindering the formation of uniform films. Gelatinization did not occur with copolysilsesquioxanes rich PTES, allowing the formation of homogeneous films improvements in thermal resistance. (author)

  16. Enzymatic Synthesis of Biobased Polyesters and Polyamides

    NARCIS (Netherlands)

    Jiang, Yi; Loos, Katja

    2016-01-01

    Nowadays, "green" is a hot topic almost everywhere, from retailers to universities to industries; and achieving a green status has become a universal aim. However, polymers are commonly considered not to be "green", being associated with massive energy consumption and severe pollution problems (for

  17. Ethynyl-Containing Aromatic Polyamide Resin.

    Science.gov (United States)

    1988-06-21

    added over two hours at 130"-150" C. and the final 17 polymer, e.g., an alcohol such as methanol, thereby ml was added over two hours at 150*-160* C...2,5A.(phayIbyly) 4,4’. Oxyd n flne 0.30 (b) 2W0 295 (c) etahaloyl chinde IV 2.S-bi(pmykihynyl) 4.,V-pbmyieue- 0.51 19 222 250 (c) tewephd loyl chloride

  18. Enzymatic Synthesis of Biobased Polyesters and Polyamides

    Directory of Open Access Journals (Sweden)

    Yi Jiang

    2016-06-01

    Full Text Available Nowadays, “green” is a hot topic almost everywhere, from retailers to universities to industries; and achieving a green status has become a universal aim. However, polymers are commonly considered not to be “green”, being associated with massive energy consumption and severe pollution problems (for example, the “Plastic Soup” as a public stereotype. To achieve green polymers, three elements should be entailed: (1 green raw materials, catalysts and solvents; (2 eco-friendly synthesis processes; and (3 sustainable polymers with a low carbon footprint, for example, (biodegradable polymers or polymers which can be recycled or disposed with a gentle environmental impact. By utilizing biobased monomers in enzymatic polymerizations, many advantageous green aspects can be fulfilled. For example, biobased monomers and enzyme catalysts are renewable materials that are derived from biomass feedstocks; enzymatic polymerizations are clean and energy saving processes; and no toxic residuals contaminate the final products. Therefore, synthesis of renewable polymers via enzymatic polymerizations of biobased monomers provides an opportunity for achieving green polymers and a future sustainable polymer industry, which will eventually play an essential role for realizing and maintaining a biobased and sustainable society.

  19. Enzymatic polymerization of biobased polyesters and polyamides

    NARCIS (Netherlands)

    Jiang, Yi

    2016-01-01

    Nowadays "green" is a hot topic almost everywhere, from retailers to universities to industries; and achieving green has become a universal perspective. However, polymers are commonly considered not to be “green”, being associated with massive energy consumption and severe pollution problems (e.g.

  20. Preparação e Caracterização de Nanofibras de Nanocompósitos de Poliamida 6,6 e Argila Montmorilonita Preparation and Characterization of Nanofibers of Polyamide 66 and Montmorillonite Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Camila R. dos Santos

    2011-01-01

    the great objective of researchers and industry, since these fibers have many applications. They can be produced by an electrospinning process from a polymeric solution. In this work, nanocomposites´ fibers of polyamide 66 and montmorillonite clay were obtained by melt mixing, following by electrospinning of the solution. Nanocomposites with three different clay concentrations, 2, 3 and 4 wt.%, were obtained by melt mixing, and solutions of these nanocomposites in formic acid were prepared at different concentrations. The influence of the clay addition, nanocomposites´ solution concentration, variation of the applied electric field on the mixture and solutions properties and on the average diameter of the nanofibers was studied. Wide-angle X-ray (WAXD and transmission electron microscopy (TEM measurements showed that the process of electrospinning was efficient in the maintenance of the clay exfoliation in the fibers. Results of scanning electron microscopy (SEM and differential scanning calorimetry (DSC showed that the fibers had average diameters of the order of nanometers, were cylindrical and not porous, having low degree of crystallinity and residual solvent. The addition of clay increased slightly the viscosity of the polymeric solution, which increased the nanofibers average diameter. It was also observed that the increase in the fiber diameters was proportional to the increase of the polymer concentration in the solution. Regarding the applied electric field, it was observed a tendency to reduction in the average diameter of the fibers with the reduction of this parameter.

  1. The influence of aging process generated by biodiesel in different conditions of time and temperature on the mechanical properties of polyamide 12; A influencia dos processos de envelhecimento gerados pelo biodiesel, em diferentes condicoes de tempo e temperatura, nas propriedades mecanicas da poliamida 12

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Roberto A.; Souza, Adriana M.C., E-mail: amcsouza@fei.edu.br [Centro Universitario da FEI, Sao Bernardo do Campo, SP (Brazil)

    2015-07-01

    This work aimed to evaluate the influence of aging processes generated by biodiesel, through immersion tests in different times (1000, 3000 and 5000 hours) and temperatures (23 and 100°C), on the mechanical properties of a commercial polyamide 12 used for fuel hoses manufacturing. Specimens were injection molded, aged and further characterized by FTIR, XRD and tensile and impact strength tests. FTIR analysis indicated a possible thermo-oxidative degradation mainly for the aging carried out at 100°C. The XRD spectra indicated an increase in the surface crystallinity of the specimens with increasing aging time for the aging carried out at 100°C. The tensile strength and elastic modulus of PA12 samples aged at 23°C decreased with increasing aging time. For the aging carried out at 100°C, the tensile strength and elastic modulus increased with aging time. The impact strength at -40°C of PA12 presented different behaviors when aged at room temperature and 100°C. (author)

  2. Migração de β-caprolactama de embalagens contendo poliamida 6 para simulante ácido acético 3% e validação do método analítico β-Caprolactam migration from polyamide 6 packaging into 3% acetic acid food simulant and validation of the analytical method

    Directory of Open Access Journals (Sweden)

    Juliana Silva Félix

    2007-08-01

    Full Text Available Este trabalho teve como objetivo desenvolver e validar método analítico para determinar ε-caprolactama no simulante de alimentos solução de ácido acético 3% e estudar sua migração de embalagens contendo poliamida 6 para o simulante em contato. Foi empregada a cromatografia gasosa usando ε-caprolactama como padrão analítico e 2-azociclononanona como padrão interno. A linearidade esteve entre 1,60 e 640,00 µg de ε-caprolactama.mL-1 de simulante, com coeficiente de correlação 0,9999. Os limites de detecção e de quantificação do método foram 0,24 e 1,60 ng, respectivamente. A precisão do método revelou valores de coeficiente de variação menores que 4,3% e a avaliação da exatidão mostrou recuperação de 100 a 106%. O método demonstrou ser eficaz para quantificar ε-caprolactama no simulante, apresentando ampla linearidade, boa precisão e exatidão. No ensaio de migração, embalagens contendo poliamida 6 foram colocadas em tubos de vidro com 10 mL do simulante, que foram hermeticamente fechados e acondicionados a 40 ± 1 °C durante 10 dias. O ensaio de migração foi realizado por imersão total. A quantidade de ε-caprolactama migrada variou de 7,8 a 10,5 e de 6,9 a 7,6 mg.kg-1 de simulante para as embalagens destinadas aos produtos cárneos e queijos, respectivamente. Todas as embalagens atenderam às exigências da Legislação Brasileira para migração de ε-caprolactama.The aim of this work was to develop and validate an analytical method to determine ε-caprolactam in 3% acetic acid solution and to study its migration from polyamide 6 into food simulant. Gas chromatography was used with ε-caprolactam as an analytical standard and 2-azacyclononanone as an internal standard. The linearity was obtained by the concentration range of 1.60 to 640.00 µg.mL-1, with a correlation coefficient of 0.9999. Detection and quantification limits of the method were 0.24 ng and 1.60 ng, respectively. Relative standard

  3. Caracterização Mecânica de Compósitos de Poliamida/Fibra de Carbono Via Ensaios de Cisalhamento Interlaminar e de Mecânica da Fratura Mechanical Characterization of Polyamide/Carbon Fiber Composites by Using Interlaminar Shear Strength and Fracture Mechanical Tests

    Directory of Open Access Journals (Sweden)

    Edson C. Botelho

    2002-01-01

    Full Text Available Compósitos termoplásticos a partir de poliamidas 6 e 6,6 e tecido de fibras de carbono com 40, 50 e 60 % em volume de reforço foram processados via moldagem por compressão a quente e caracterizados por ensaios mecânicos destrutivos (cisalhamento interlaminar em três pontos (short-beam, cisalhamento interlaminar por compressão (CST e ensaios de mecânica da fratura e por inspeção não-destrutiva (ultra-som e microscopias óptica e eletrônica de varredura. Os resultados obtidos mostraram que os compósitos termoplásticos processados apresentaram uma distribuição homogênea do polímero no reforço. Entretanto, nos compósitos com maior quantidade de poliamida (40 % de reforço foram observadas regiões ricas em matriz entre as camadas de tecido. Os ensaios de mecânica da fratura (DCB e ENF e de cisalhamento interlaminar em três pontos não apresentaram falha interlaminar, não sendo observada a propagação de trincas de forma homogênea e retilínea no interior do material. Em função destes resultados foi utilizado o ensaio de cisalhamento por compressão, desenvolvido no Institute of Polymer Research Dresden da Alemanha, que permitiu uma caracterização mais precisa dos compósitos termoplásticos estudados. Foi observado também, a partir dos ensaios de CST, que os compósitos obtidos da poliamida 6,6 apresentaram um aumento no valor do cisalhamento interlaminar de até 20 % com o aumento do volume de fibras.Thermoplastics composites of polyamide 6 and 6.6 reinforced with carbon fiber fabric were obtained by compression molding and characterized by destructive (short-beam, compression shear (CST and fracture mechanics testing as well as by non-destructive inspection (ultrasound analysis, optical and scanning electron microscopy. The results show that, in general, the matrix was homogeneously distributed about the reinforcing fabric. However, for the composites with higher polyamide content (>50% matrix-rich regions were

  4. Biomimetic routes to nanoscale-toughened oxide ceramics

    Science.gov (United States)

    Deschaume, Olivier

    In this work, a novel anion exchange technique has been developed and optimised in order to prepare extra-pure, hydroxide-free solutions of aluminium polyoxocations (A113 and A130) as well as for the preparation of nanosized, highly monodisperse aluminium hydroxide particles in the particle size range 20-200nm. In order for the evolution and composition of the resulting systems to be monitored, an array of characterisation techniques including 27A1 NMR, dynamic light scattering, po-tentiometry, conductometry and UV-Vis spectroscopy, have been implemented and complemented with successful data treatment strategies. The quantitative data obtained indicates that the static anion exchange method is a soft, environmentally friendly, low-cost, energy-saving and convenient procedure for the preparation of Al- containing model systems. The A1 species obtained can be used for high-precision model studies on A1 speciation, and serve as nanosize precursors to a variety of Al-containing materials. The use of these pure A1 precursors has a clear advantage in materials synthesis arising from an improved understanding and better control of A1 speciation. In a second development of the project, the model systems have been used in a nanotectonic approach to biomimetic materials synthesis, with possible applications to the optimisation of Al-containing materials such as ceramics or composite films. Bearing this aim in mind, the interactions of the prepared aluminium species with the model protein BSA and a bioelastomer, elastin, were monitored and the resulting composite materials characterised. The methodology developed for the synthesis and characterisation of pure A1 species and A1 species/biomolecule systems is a robust base for further studies spanning research fields such as Chemistry, Biology or Environmental sciences, and possess a large potential for application to industrial products and processes.

  5. Dispersion toughened ceramic composites and method for making same

    Science.gov (United States)

    Stinton, D.P.; Lackey, W.J.; Lauf, R.J.

    1984-09-28

    Ceramic composites exhibiting increased fracture toughness are produced by the simultaneous codeposition of silicon carbide and titanium disilicide by chemical vapor deposition. A mixture of hydrogen, methyltrichlorosilane and titanium tetrachloride is introduced into a furnace containing a substrate such as graphite or silicon carbide. The thermal decomposition of the methyltrichlorosilane provides a silicon carbide matrix phase and the decomposition of the titanium tetrachloride provides a uniformly dispersed second phase of the intermetallic titanium disilicide within the matrix phase. The fracture toughness of the ceramic composite is in the range of about 6.5 to 7.0 MPa..sqrt..m which represents a significant increase over that of silicon carbide.

  6. Tattooing to "Toughen up": Tattoo experience and secretory immunoglobulin A.

    Science.gov (United States)

    Lynn, Christopher D; Dominguez, Johnna T; DeCaro, Jason A

    2016-09-10

    A costly signaling model suggests tattooing inoculates the immune system to heightened vigilance against stressors associated with soft tissue damage. We sought to investigate this "inoculation hypothesis" of tattooing as a costly honest signal of fitness. We hypothesized that the immune system habituates to the tattooing stressor in repeatedly tattooed individuals and that immune response to the stress of the tattooing process would correlate with lifetime tattoo experience. Participants were 24 women and 5 men (aged 18-47). We measured immune function using secretory immunoglobulin A (SIgA) and cortisol (sCORT) in saliva collected before and after tattoo sessions. We measured tattoo experience as a sum of number of tattoos, lifetime hours tattooed, years since first tattoo, percent of body covered, and number of tattoo sessions. We predicted an inverse relationship between SIgA and sCORT and less SIgA immunosuppression among those with more tattoo experience. We used hierarchical multiple regression to test for a main effect of tattoo experience on post-tattoo SIgA, controlling for pretest SIgA, tattoo session duration, body mass, and the interaction between tattoo experience and test session duration. The regression model was significant (P = 0.006) with a large effect size (r(2)  = 0.711) and significant and positive main (P = 0.03) and interaction effects (P = 0.014). Our data suggest that the body habituates over time to the tattooing stressor. It is possible that individuals with healthy immune systems heal faster, making them more likely to get multiple tattoos. Am. J. Hum. Biol. 28:603-609, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Toughening elastomers with sacrificial bonds and watching them break

    NARCIS (Netherlands)

    Ducrot, E.; Chen, Y.; Bulters, M.J.H.; Sijbesma, R.P.; Creton, C.

    2014-01-01

    Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4

  8. Toughening elastomers with sacrificial bonds and watching them break.

    Science.gov (United States)

    Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

    2014-04-11

    Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials.

  9. The development of Zirconia and Copper toughened Alumina ceramic insert

    Science.gov (United States)

    Amalina Sabuan, Nur; Zolkafli, Nurfatini; Mebrahitom, A.; Azhari, Azmir; Mamat, Othman

    2018-04-01

    Ceramic cutting tools have been utilized in industry for over a century for its productivity and efficiency in machine tools and cutting tool material. However, due to the brittleness property the application has been limited. In order to manufacture high strength ceramic cutting tools, there is a need for suitable reinforcement to improve its toughness. In this case, copper (Cu) and zirconia (ZrO2) powders were added to investigate the hardness and physical properties of the developed composite insert. A uniaxial pre-forming process of the mix powder was done prior to densification by sintering at 1000 and 1300°C. The effect of the composition of the reinforcement on the hardness, density, shrinkage and microstructure of the inserts was investigated. It was found that an optimum density of 3.26 % and hardness 1385HV was obtained for composite of 10wt % zirconia and 10wt% copper at temperature 1000 °C.

  10. Isocyanate toughened pCBT: Reactive blending and tensile properties

    Directory of Open Access Journals (Sweden)

    T. Abt

    2013-02-01

    Full Text Available Cyclic butylene terephthalate oligomers (CBT were reacted in a ring-opening polymerization with three types of isocyanates: a bifunctional aromatic type, a bifunctional aliphatic type and a polymeric aromatic isocyanate. All reactions took place in a batch mixer. The use of 0.5 to 1 wt% isocyanate led to a dramatic increase in elongation at break of polymerized cyclic butylene terephthalate (pCBT, from 8 to above 100%. The stiffness and strength of the modified pCBT, however, were found to slightly decrease. Proton nuclear magnetic resonance (NMR analysis shows that the formation of thermally stable amide groups is the dominant chain extension reaction mechanism. Gel content measurements suggest a linear structure for samples containing bifunctional isocyanates while pCBT modified with polyfunctional isocyanate exhibited some gel formation at higher isocyanate content. Melting and crystallization temperatures as well as degree of crystallinity were found to decrease with increasing isocyanate content. No phase separation was detected by scanning electron microscopy (SEM analysis. Moreover, a high degree of polymerization is deduced due to the absence of CBT oligomer crystals.

  11. Zirconia toughened mica glass ceramics for dental restorations.

    Science.gov (United States)

    Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

    2018-03-01

    The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. Uncovering and Validating Toughening Mechanisms in High Performance Composites

    Science.gov (United States)

    2015-09-17

    tan dY Z X dX φ" #= $ % & ’ (1) The local coordinate systems of continuous twisted crack (x’, y’, z’) are to be defined based on the...Suksangpanya (The entire project) -! Nicolas Guarin (funded from other sources) -! David Restrepo (minimum involvement, funded from other sources

  13. Toughened microstructures for ductile phase reinforced molybdenum disilicide

    International Nuclear Information System (INIS)

    Pickard, S.M.; Ghosh, A.K.

    1995-01-01

    Various morphologies of ductile Nb refractory metal reinforcement are incorporated into a MoSi 2 matrix using powder metallurgy, including single-ply laminates, continuous metal ribbons and sections of 2-dimensional wire mesh. Hot forging techniques are used to redistribute the reinforcement and change the dimensions and the aspect ratio of the reinforcing metal ligaments. Work-of-rupture measurements are conducted on bend test specimens and precracked tensile specimens of the composite so that the toughness contribution from the various ductile metal morphologies can be assessed according to its effectiveness. Accompanying microstructural examination of crack bridging interaction with the reinforcement is conducted

  14. Interface-induced electronic structure toughening of nitride superlattices

    Czech Academy of Sciences Publication Activity Database

    Řehák, Petr; Černý, Miroslav; Holec, D.

    2017-01-01

    Roč. 325, SEP (2017), s. 410-416 ISSN 0257-8972 R&D Projects: GA ČR(CZ) GA16-24711S Institutional support: RVO:68081723 Keywords : Ab initio calculations * Cleavage * Friedel oscillations * Nitride multilayers Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.589, year: 2016

  15. Ceramics in engines - Long term stability of transformation toughened zirconia

    International Nuclear Information System (INIS)

    Marmach, M.; Swain, M.V.

    1985-01-01

    The long term thermal stability of two types of magnesia partially stabilized zirconia at temperatures below 1000 0 C has been determined. The effect on mechanical properties and phase stability of isothermal heating at 800 0 C and 900 0 C for up to 2000 hours, and with thermal cycling for a similar period between R.T. and 800 0 C in air, was measured. it was found that peak-aged (MS) type Mg-PSZ was much more stable than the thermal shock resistant (TS) type in both tests and showed minimal degradation

  16. Biodegradable toughened nanohybrid shape memory polymer for smart biomedical applications.

    Science.gov (United States)

    Biswas, Arpan; Singh, Akhand Pratap; Rana, Dipak; Aswal, Vinod K; Maiti, Pralay

    2018-05-17

    A polyurethane nanohybrid has been prepared through the in situ polymerization of an aliphatic diisocyanate, ester polyol and a chain extender in the presence of two-dimensional platelets. Polymerization within the platelet galleries helps to intercalate, generate diverse nanostructure and improve the nano to macro scale self-assembly, which leads to a significant enhancement in the toughness and thermal stability of the nanohybrid in comparison to pure polyurethane. The extensive interactions, the reason for property enhancement, between nanoplatelets and polymer chains are revealed through spectroscopic measurements and thermal studies. The nanohybrid exhibits significant improvement in the shape memory phenomena (91% recovery) at the physiological temperature, which makes it suitable for many biomedical applications. The structural alteration, studied through temperature dependent small angle neutron scattering and X-ray diffraction, along with unique crystallization behavior have extensively revealed the special shape memory behavior of this nanohybrid and facilitated the understanding of the molecular flipping in the presence of nanoplatelets. Cell line studies and subsequent imaging testify that this nanohybrid is a superior biomaterial that is suitable for use in the biomedical arena. In vivo studies on albino rats exhibit the potential of the shape memory effect of the nanohybrid as a self-tightening suture in keyhole surgery by appropriately closing the lips of the wound through the recovery of the programmed shape at physiological temperature with faster healing of the wound and without the formation of any scar. Further, the improved biodegradable nature along with the rapid self-expanding ability of the nanohybrid at 37 °C make it appropriate for many biomedical applications including a self-expanding stent for occlusion recovery due to its tough and flexible nature.

  17. Multi-scale Multi-mechanism Toughening of Hydrogels

    Science.gov (United States)

    Zhao, Xuanhe

    Hydrogels are widely used as scaffolds for tissue engineering, vehicles for drug delivery, actuators for optics and fluidics, and model extracellular matrices for biological studies. The scope of hydrogel applications, however, is often severely limited by their mechanical properties. Inspired by the mechanics and hierarchical structures of tough biological tissues, we propose that a general principle for the design of tough hydrogels is to implement two mechanisms for dissipating mechanical energy and maintaining high elasticity in hydrogels. A particularly promising strategy for the design is to integrate multiple pairs of mechanisms across multiple length scales into a hydrogel. We develop a multiscale theoretical framework to quantitatively guide the design of tough hydrogels. On the network level, we have developed micro-physical models to characterize the evolution of polymer networks under deformation. On the continuum level, we have implemented constitutive laws formulated from the network-level models into a coupled cohesive-zone and Mullins-effect model to quantitatively predict crack propagation and fracture toughness of hydrogels. Guided by the design principle and quantitative model, we will demonstrate a set of new hydrogels, based on diverse types of polymers, yet can achieve extremely high toughness superior to their natural counterparts such as cartilages. The work was supported by NSF(No. CMMI- 1253495) and ONR (No. N00014-14-1-0528).

  18. Obtenção de um revestimento compósito de poliéster-uretana reforçado com alumina pela técnica de deposição por imersão sobre fibras de poliamida 6 Preparation of a composite coating of alumina reinforced polyester urethane by dip coating on polyamide 6 fibers

    Directory of Open Access Journals (Sweden)

    F. A. L. Sánchez

    2009-12-01

    Full Text Available O uso de revestimentos compósitos de matriz polimérica e reforço cerâmico capazes de manter a flexibilidade e a elasticidade das fibras poliméricas, agregando propriedades típicas dos materiais cerâmicos (como ação bactericida ou fotocatalítica, resistência à chama, ao desgaste e à abrasão, tem atraído interesse da indústria têxtil. Baseado na técnica dip coating e usando fibras sintéticas de poliamida como substrato, foram produzidas suspensões de poliéster-uretana com partículas de alumina (tamanho médio de partícula 2,2 μm para obtenção de revestimentos uniformes e espessos sobre o material base, poliamida 6. A viscosidade das suspensões foi controlada pela adição de carboximetilcelulose e avaliada por reometria rotacional. A distribuição granulométrica das suspensões também foi determinada. Os parâmetros operacionais do dip coating, i.e., velocidade de bobinamento e temperatura dos fornos, foram mantidos constantes em todas as amostras. O processo mostrou viabilidade para deposição uniforme do recobrimento avaliado, com espessura adequada, indicando ser promissor para revestir fibras, agregando propriedades de interesse tecnológico.Ceramic reinforced polymer composite coatings that can retain the flexibility and elasticity of the polymeric fibers, being also able to incorporate the functionality of ceramic materials (e.g. fire, wear, or abrasion resistance, antibacterial performance, photocatalytic effect are interesting to the processing of textile materials. In this work, polyester-urethane slurries with alumina particles (mean particle size: 2.2 μm were developed based on the dip coating technique and using polyamide-6 synthetic fibers as the substrate, seeking to obtain an uniform and thick coating. The viscosity of the slurries was varied using carboxymethylcellulose as a rheological agent and evaluated by rotational rheometry. Particle size distribution of the slurries was also analyzed. The

  19. Reciclagem de rejeitos de poli(tereftalato de etileno (PET e de poliamida (PA por meio de extrusão reativa para a preparação de blendas Recycling of wastes from poly(ethylene tereftalate (PET and polyamide (PA by reactive extrusion for preparation of polymeric blends

    Directory of Open Access Journals (Sweden)

    Caio T Ferreira

    2011-01-01

    Full Text Available O consumo crescente de materiais poliméricos em diversas formas de aplicação leva à produção de uma quantidade enorme de resíduos pós-consumo e pós-industriais com potencial poluidor elevado. A reciclagem mecânica é uma das maneiras mais adequadas para contornar os problemas gerados por estes rejeitos, uma vez que permite conciliar interesse econômico com benefícios ambientais. Neste trabalho foi feito um estudo sobre a reciclagem de rejeitos pós-industriais de poli(tereftalato de etileno (PET provenientes da fabricação de mantas de tecido não tecido e de resíduos de poliamida (PA oriundos de pneus usados na forma de blendas, produzidas por meio de extrusão reativa dos dois resíduos em presença de catalisador. Os resultados obtidos a partir de caracterização térmica e química das blendas evidenciaram a ocorrência de trans-reações entre segmentos de cadeia polimérica dos dois polímeros, possibilitando a compatibilização do sistema. A produção de blendas PET/PA se configura como uma forma adequada para a reciclagem dos rejeitos de PET e de PA.The increasing use of polymeric materials in several applications leads to the production of a high amount of post consume and post industrial wastes with expressive pollutant potential. Mechanical recycling is an important way to decrease the problems caused by these wastes because it allows one to associate economic viability with environmental benefits. In this paper a study was carried out on the recycling of poly(ethylene tereftalate (PET wastes from the production of nonwoven fabrics (NWF and of polyamide (PA wastes from old tires for production of polymeric blends via reactive extrusion in the presence of trans-reaction catalysts. The results from thermal and chemical characterization indicated trans-reactions between segments of polymeric chains of the two polymers, promoting the system compatibilization. The production of PET/PA blends is an interesting alternative

  20. Estudo das propriedades reológicas, morfológicas e mecânicas de blendas injetadas de polipropileno com poliamidas reforçadas com fibras de vidro An experimental study of the rheological, morphological and mechanical properties of reinforced polypropylene/polyamide blends

    Directory of Open Access Journals (Sweden)

    G. Villoutreix

    1998-12-01

    Full Text Available RESUMO: Neste trabalho foi estudada a influência da adição de compatibilizantes, da composição e dos parâmetros de processamento nas propriedades reológicas, morfológicas e mecânicas de blendas de polipropileno com poliamidas aromáticas, adicionadas de fibras de vidro, obtidas por moldagem por injeção. Os resultados obtidos mostram que a adição de um compatibilizante melhora a adesão entre as fases da blenda, apresentando um papel emulsificante e estabilizador da morfologia da blenda. Utilizando-se um reômetro "in line" na máquina de injeção, e através de observações morfológicas, foi mostrado que ocorre uma evolução significativa da morfologia em função dos parâmetros de processamento e da composição da blenda. A orientação das fibras de vidro em função da posição dentro do molde foi também estudada neste trabalho, demonstrando a existência de três camadas distintas no molde.ABSTRACT: In this work, the influence of compatibilization, blend composition and processing parameters on the rheological, morphological and mechanical properties were studied for blends of polypropylene with aromatic polyamide with glass fibers obtained by injection molding. It was shown that the compatibilizer improves the adhesion at the interface, emulsifies and stabilizes the morphology. Using rheological data obtained with an in-line rheometer, localized in the injection molding machine and morphological observations, it was shown that significant evolution of phase structure occurred depending on processing or compounding parameters. Also, the orientation of the glass fibers was studied as a function of the position in the mold cavity, showing the presence of three layers of different morphology in the molding.