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Sample records for acrylic composites loaded

  1. Radiation sensitive acrylate composition

    This application relates to radiation-sensitive compositions and more particularly to such compositions comprising acrylated esters. As used in this specification, the term acrylated esters refers to either acrylic or methacrylic acid resins. 3 tabs

  2. Permittivity and Electromagnetic Interference Shielding Investigations of Activated Charcoal Loaded Acrylic Coating Compositions

    Sharief ud Din Khan

    2014-01-01

    Full Text Available Acrylic resin (AR based electromagnetic interference (EMI shielding composites have been prepared by incorporation of up to 30 wt% activated charcoal (AC in AR matrix. These composites have been characterized by XRD, Raman spectroscopy, scanning electron microscopy, dielectric, and EMI shielding measurement techniques. XRD patterns and Raman studies confirm the incorporation of AC particles inside AR matrix and suggest possible interactions between phases. The SEM images show that incorporation of AC particles leads to systematic change in the morphology of composites especially the formation of porous structure. The dielectric measurements show that 30 wt% AC loading composite display higher relative permittivity value (~79 compared to pristine AR (~5. Further, the porous structure, electrical conductivity, and permittivity value contribute towards EMI shielding effectiveness value of −36 dB (attenuation of >99.9% of incident radiation for these composites, thereby demonstrating their suitability for making efficient EMI shielding coatings.

  3. Permittivity and Electromagnetic Interference Shielding Investigations of Activated Charcoal Loaded Acrylic Coating Compositions

    Sharief ud Din Khan; Manju Arora; Wahab, M. A.; Parveen Saini

    2014-01-01

    Acrylic resin (AR) based electromagnetic interference (EMI) shielding composites have been prepared by incorporation of up to 30 wt% activated charcoal (AC) in AR matrix. These composites have been characterized by XRD, Raman spectroscopy, scanning electron microscopy, dielectric, and EMI shielding measurement techniques. XRD patterns and Raman studies confirm the incorporation of AC particles inside AR matrix and suggest possible interactions between phases. The SEM images show that incorpo...

  4. Poly(lauryl acrylate) and poly(stearyl acrylate) grafted multiwalled carbon nanotubes for polypropylene composites

    Daugaard, Anders Egede; Jankova Atanasova, Katja; Hvilsted, Søren

    2014-01-01

    , polymerizations of lauryl or stearyl acrylate were performed, resulting in two novel polymer modifications on the MWCNT (poly(lauryl acrylate) or poly(stearyl acrylate)). The method was found to give time dependent loading of polymers as a function of time (up to 38 wt% for both acrylates), and showed a plateau...... were found to be substantially improved, where poly(lauryl acrylate) was found to be the superior surface modification, resulting in a conductive composite....

  5. Synergistic effect of additives including multifunctional acrylates in wood plastic composites

    Wood Plastic Composite (WPC) was prepared with simul (soft wood, density = 0.4g/cc) and butylmethacrylate (BMA) monomer using 10% methanol as the swelling agent. Effect of additives including multifunctional acrylates such as tripropylene glycol diacrylate (TPGDA), trimethylol propane triacrylate (TMPTA), oligomer acrylates like the urethane (UA), epoxy (EA) and polyester (PEA) acrylates and N-vinyl pyrrolidone (NVP) was investigated using 1 to 3 Mrad dose at 0.8 Mrad/h. Synergistic increases in polymer loading yields was achieved in presence of the additives, particularly with the trifunctional acrylate (TMPTA). In addition, acid as well as urea were also used as co-additives and synergistic enhancement in yields of polymer loading were obtained. The synergistic polymer loading by acid addition causes substantial decrease in tensile strength of the composite; but other additives and co-additives increase both the polymer loading and the tensile strength in these systems. (author)

  6. Radiation hardening of epoxide-acrylate compositions

    Radiation setting of epoxy oligomers modified with vinyl monomers was studied. The setting was accomplished under the effect of γ-radiation of 60Co at the dose rate of 1750 Mrad/s. The content of the gel fraction in the radiation set epoxy-acrylate-styrene compositions increases by 20%, and the phase transition temperature is higher than for compositions set under normal conditions. In all compositions investigated the maximum content of the gel fraction is observed at 8-9 Mrad dose and is 60-70%, on the average. An increase in degree of setting up to 92-98% can be achieved by additional heat treatment of the compositions

  7. Biocompatibility of alendronate-loaded acrylic cement for vertebroplasty

    T Calvo-Fernández

    2010-10-01

    Full Text Available This paper reports a biological evaluation of a non-resorbable acrylic cement loaded with alendronate for the treatment of osteoporotic vertebral compression fractures. The cement formulation was based on polymethyl methacrylate and acrylic monomers; one of these had covalently linked vitamin E residues. The same cement in the absence of alendronate was used as a control. The setting of the charged cement presented a maximum polymerization temperature of 44ºC, a setting time of 24 min, a residual monomer content lower than 3 wt.%, a compressive strength of 99±10 MPa and an elastic modulus of 1.2±0.2 GPa. Cytotoxicity studies using human osteoblast cultures revealed that the leachable substances of the alendronate loaded cement collected between 1 and 7 days decreased cell viability to values lower than 80%. However, morphological changes and cellular damage in cells produced by the extracts decreased with the leak time. Cell adhesion and growth on charged cement was significantly lower than on the control. Implantation of the cement paste in the intra-femoral cavity of rabbits showed that initially the osteogenic activity was evident for the cement charged with alendronate, and the osteosynthesis process took place mainly in the trabeculae and was manifested by the presence of a non-mineralised osseous spicule. The interface between material and adjacent bone tissue was initially characterized by a variable fibrous response that in many cases it appeared reduced to thin connective tissue after a 24-week-period.

  8. Radiation cross-linking of epoxide-acrylic compositions

    The process of hardening of epoxy-acryl compositions on copper, aluminium, iron, and glass substrates has been studied under the action of ionizing radiation (accelerated electrons, γ-radiation). Irradiated samples have been heat treated for 2 hours at 100 and 150 deg C for accelerating posteffect. In the epoxy oligomer-acrylic acid system structurization is completed at a dose of 10-12 Mrad. The content of gel fraction equals 30-62% when irradiation is performed in air and up to 85% when the samples are irradiated under film. The effect has been established of natural epoxy oligomers and various plasticizers on the structurization process. The possibility has been shown of obtaining heat-resistant coatings based on epoxy oligomers

  9. Antifouling foldable acrylic IOLs loaded with norfloxacin by aqueous soaking and by supercritical carbon dioxide technology.

    González-Chomón, Clara; Braga, Mara E M; de Sousa, Herminio C; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2012-10-01

    Cataracts treatment usually involves the extraction of the opaque crystalline lens and its replacement by an intraocular lens (IOL). A serious complication is the occurrence of endophthalmitis, a post-surgery infection mainly caused by Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa. IOLs having the ability to load and to release norfloxacin in a controlled way and at efficient therapeutic levels may help to overcome these issues. In this work, acrylic hydrogels combining 2-hydroxyethyl methacrylate (HEMA) and 2-butoxyethyl methacrylate (BEM) at various ratios were prepared to attain biocompatible networks that can be foldable even in the dry state and thus insertable through minor ocular incision, and that load therapeutic amounts of norfloxacin. Acrylamide (AAm) and methacrylic acid (MAAc) were also incorporated as functional comonomers in small proportions. Water sorption, contact angle, protein adsorption, and optical properties of the networks were characterized. BEM notably decreased the T(g) of the networks, but also the loading by immersion in aqueous solution (presoaking). Then, a scCO(2)-based impregnation/deposition (SSI) method was implemented to improve the uptake of the drug. Loading capacities were discussed in terms of the comonomers composition and the employed method and operational conditions. The networks prepared with HEMA/BEM 20:80 vol/vol and processed with supercritical fluids combine adequate mechanical properties, biocompatibility and norfloxacin loading/release, and seem to be suitable for developing norfloxacin-eluting IOLs. PMID:22846620

  10. Influence of Sea Water Aging on the Mechanical Behaviour of Acrylic Matrix Composites

    Davies, P.; Le Gac, P.-Y.; Le Gall, M.

    2016-07-01

    A new matrix resin was recently introduced for composite materials, based on acrylic resin chemistry allowing standard room temperature infusion techniques to be used to produce recyclable thermoplastic composites. This is a significant advance, particularly for more environmentally-friendly production of large marine structures such as boats. However, for such applications it is essential to demonstrate that composites produced with these resins resist sea water exposure in service. This paper presents results from a wet aging study of unreinforced acrylic and glass and carbon fibre reinforced acrylic composites. It is shown that the acrylic matrix resin is very stable in seawater, showing lower property losses after seawater aging than those of a commonly-used epoxy matrix resin. Carbon fibre reinforced acrylic also shows good property retention after aging, while reductions in glass fibre reinforced composite strengths suggest that specific glass fibre sizing may be required for optimum durability.

  11. The influence of ultrasound on the release of gentamicin from antibiotic-loaded acrylic beads and bone cements

    Ensing, GT; Hendriks, JGE; Jongsma, JE; van Horn, [No Value; van der Mei, HC; Busscher, HJ

    2005-01-01

    Gentamicin-loaded acrylic beads are loosely placed in infected bone cavities, whereas gentamicin-loaded acrylic bone cement is used as a mechanical filler in bone to anchor prosthetic components. Both drug delivery systems are used to decrease infection rates by gentamicin release. The objective of

  12. Loading rate effects on the fracture of Ni/Au nano-coated acrylic particles

    Zhang, Z. L.; He, J. Y.; Nagao, S; Kristiansen, H.

    2012-01-01

    Mechanical failure of monodisperse Ni/Au coated acrylic particles has been investigated by individual compression tests using nanoindentation-based technique equipped with a flat diamond punch. We have found that both fracture property and morphology of particles depend on the compression loading rate. The breaking strain of the metal coating decreases with increasing loading rate, while the breaking stress increases. Two obvious fracture patterns with cracking in meridian or latitude directi...

  13. Synthesis of Acrylic Acid/Kaoline Powder Superabsorbent Composite by Inverse-suspending Polymerization

    ZHONG Jin-feng; XUE Yi-ming; WU Ji-huai; LIN Jian-ming; WEI Yue-lin

    2004-01-01

    An acrylic acid/kaoline powder superabsorbent composite with a water absorbency of the superabsorbent composite about 1/800 was synthesized by inverse-suspending polymerization reaction between acrylic acid monomer and kaoline ultrafine powder. The influence of the dispersant agent on the configuration of the products in the inverse suspension polymerization is investigated. The influences of the kaoline powder, cross-linker, initiator, neutralization degree and the volume ratio of oil to water phase on the water absorbency of the superabsorbent composites are discussed in the paper.

  14. Loading rate effects on the fracture of Ni/Au nano-coated acrylic particles

    Z. L. Zhang

    2012-03-01

    Full Text Available Mechanical failure of monodisperse Ni/Au coated acrylic particles has been investigated by individual compression tests using nanoindentation-based technique equipped with a flat diamond punch. We have found that both fracture property and morphology of particles depend on the compression loading rate. The breaking strain of the metal coating decreases with increasing loading rate, while the breaking stress increases. Two obvious fracture patterns with cracking in meridian or latitude direction are identified according to the loading rate, and attributed respectively to tension- or bendingdominated deformation of the coating. The findings reported here give a significant guiding to the manufacture design of metal coated polymer particles for Anisotropic Conductive Adhesive (ACA packaging.

  15. Synthesis and characterization of poly(sodium acrylate)/ bentonite superabsorbent composite

    Poly(sodium acrylate)/bentonite superabsorbent composite with water absorbency 1562 g·g−1 was synthesized by inverse suspension polymerization. The introduction of bentonite improves the water absorbency and facilitates the particle size even distribution of the composite. The network structure in the superabsorbent hydrogel is confirmed.

  16. Preparation and characteristics of acrylic acid/styrene composite plasma polymerized membranes

    Plasma polymerization has gained increasing interest for the deposition of functional plasma-polymerized membranes suitable for a wide range of applications on account of its advantageous features. In this work, acrylic acid/styrene composite plasma polymerized membranes were synthesized by plasma polymerization of a mixture of acrylic acid and styrene monomers in a low-frequency after-glow capacitively coupled plasma (CCP) discharge process. The structure and composition of the plasma polymerized membranes were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed that the partial pressure ratio between acrylic acid (AA) and styrene (St), applied discharge power and the energy of the extracted particles have considerable effects on the structure and the content of functional groups of the deposited membranes.

  17. Stiffness and strength of composite acrylic bone cements

    I. Knets

    2007-01-01

    Full Text Available Purpose: Different acrylic bone cements based upon PMMA-MMA system are applicable for implant fixation inbone tissue. The aim of present study is the optimisation of the structure of some new bone acrylic cements madeon the basis of PMMA-ethylmethacrylate-triethyleneglycoldimethacrylate and bone cements having additives (HAand radio pacifier, and the finding of the effect of these modifications on the flexural strength and stiffness.Design/methodology/approach: Different new bone cements on the basis of PMMA-EMA-TEGDMA system(ABC were developed experimentally. The stiffness and strength of the samples of these modified cements weredetermined in the special three point bending equipment.Findings: A comparison of the flexural properties of new PMMA-EMA-TEGDMA cements and commercialavailable PMMA-MMA cement showed that commercial bone cement had larger values of ultimate strengthand modulus of elasticity, but the difference is not very important. As concerns the polymerisation peaktemperature, then there is a significant difference between commercial PMMA-MMA cement (~ 800C andPMMA-EMA-TEGDMA modified cements (50 – 600C. The introduction of 10% and 18% of HA into solidphase does not influence essentially strength and modulus of elasticity of the PMMA-EMA-TEGDMA bonecements. The introduction of radio pacifier BaSO4 into bone cement leads to flexural strength diminishing.Low polymerisation peak temperature and appropriate mechanical properties of bone cements developed allowsregarding new 3-D structure acrylic bone cements as promising biomaterials.Research limitations/implications: It is supposed to carry out animal testing to learn more about reaction ofmodified implanted material on the biological environment.Practical implications: The new materials could be efficiently used as bone cements because they will notdamage surrounding biological tissue during curing.Originality/value: Paper is providing the new information about possibilities to

  18. Polypyrrole-coated styrene-butyl acrylate copolymer composite particles with tunable conductivity

    HUANG Liyan; HOU Wenbo; LIU Zhengping; ZHANG Qingyue

    2005-01-01

    A series of near or monodisperse styrene-butyl acrylate (SBA) copolymer latex particles with different butyl acrylate contents were coated with polypyrrole. The structure of the SBA/PPy composites was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and standard four-probe method. The core-shell morphology of the SBA/PPy composite particles was confirmed. The result of DSC showed that Tg of the composite is mainly determined by the core component. The effects of the concentration of polypyrrole, the butyl acrylate content in SBA copolymer and the nature of the counter-anion on the electrical conductivity of compression-moulded samples were studied. It was first found that the electrical conductivity of the samples can be tuned by varying the butyl acrylate content in SBA copolymer and the highest conductivity of the core-shell composite was 0.17 S·cm-1.

  19. Characterization and Absorbing Properties of Oil Palm Empty Fruit Bunch Filled Poly (Acrylic Acid-co-Acrylamide) Super absorbent Polymer Composites

    Oil palm empty fruit bunch graft poly (acrylic acid-co-acrylamide) super absorbent composite (OPEFB-g-(PAA-co-PAM) SAPC) was synthesized by graft copolymerization of the acrylic acid (AA) and acrylamide (AM) comonomer onto OPEFB fibre using ammonium persulfate (APS) and N,N-methylene bisacarylamide (MBA) as an initiator and crosslinked, respectively. The absorbency in various chloride salt solutions indicated that the absorbency decreased with increasing ionic strength of the salt solutions. Moreover, the absorbency under load (AUL) of SAPC was investigated at various applied loading and results show that, AUL decreased with increasing applied loading. Infrared Spectroscopy (IR) and Thermogravimetric Analysis (TGA) were carried out to confirm the chemical structure and thermal properties of the synthesized super absorbent, respectively. (author)

  20. Effect of Additives on UV-Activated Urethane Acrylate Polymerization Composite Coatings

    Zane GRIGALE-SOROCINA; Martins KALNINS; Jana SIMANOVSKA; Elīna VINDEDZE; Ingmars BIRKS; Evita BRAZDAUSKA

    2016-01-01

    An increased demand for new and improved coating systems, for environmental & health & safety and performance reasons, have appeared during the recent decades. Currently, there is new interest in preparation of thin UV curable urethane acrylate (UA) composite coatings with short-term properties. Cellulose based additives: nitrocellulose, cellulose acetate butyrate, sucrose benzoate and silica were evaluated to determine their influence on unreacted composite characteristics (viscosity, pigmen...

  1. Effect of Additives on UV-activated Urethane Acrylate Polymerization Composite Coatings

    Zane GRIGALE-SOROCINA

    2016-05-01

    Full Text Available An increased demand for new and improved coating systems, for environmental & health & safety and performance reasons, have appeared during the recent decades. Currently, there is new interest in preparation of thin UV curable urethane acrylate (UA composite coatings with short-term properties. Cellulose based additives: nitrocellulose, cellulose acetate butyrate, sucrose benzoate and silica were evaluated to determine their influence on unreacted composite characteristics (viscosity, pigment suspension stability and characteristics of cured film (ultimate tensile strength, elongation at break, surface gloss, surface scratch resistance and film adhesion loss time. The most suitable additive content was found to provide required viscosity. All additives increase surface scratch resistance, but cellulose based additives increase surface gloss values and decrease the time of adhesion loss. Silica has great effect on the interaction between linear and hyperbranched urethane acrylates, which has crucial influence on the stability of uncured pigmented mixture samples.

  2. Real-time monitoring of graphene oxide reduction in acrylic printable composite inks

    Porro, S.; Giardi, R.; Chiolerio, A.

    2014-06-01

    This work reports the electrical characterization of a water-based graphene oxide/acrylic composite material, which was directly inkjet printed to fabricate dissipative patterns. The graphene oxide filler, which is strongly hydrophilic due to its heavily oxygenated surface and can be readily dispersed in water, was reduced by UV irradiation during photo-curing of the polymeric matrix. The concurrent polymerization of the acrylic matrix and reduction of graphene oxide filler was demonstrated by real-time resistance measurements during UV light irradiation. The presence of graphene filler allowed decreasing the resistance of the pure polymeric matrix by nearly five orders of magnitude. This was explained by the fact that clusters of reduced graphene oxide inside the polymer matrix act as preferential pathways for the mobility of charge carriers, thus leading to an overall decrease of the material's resistance.

  3. Influence of Methacrylic-Acrylic Copolymer Composition on Plasticiser-free Optode Films for pH Sensors

    Musa Ahmad; Loh Han Chern; Teh Huey Fang; Lee Yook Heng

    2003-01-01

    In this work we have examined the use of plasticiser-free polymeric films incorporating a proton selective chromoionophore for optical pH sensor. Four types of methacrylic-acrylic copolymers containing different compositions of n-butyl acrylate (nBA) and methyl methacrylate (MMA) were synthesised for use as optical sensor films. The copolymers were mixed with appropriate amounts of chromoionophore (ETH5294) and a lipophilic salt before spin coated on glass slides to form films for the evaluat...

  4. Mechanical and thermal properties of UV curable polyurethane acrylate composite coatings

    UV curable coating formulation comprises urethane acrylate resin and nano silica as filter were synthesized to develop UV curable inorganic hybrid composite (PUA). The surface of the nano silica was chemically modified to improve its chemical interaction within the urethane acrylate matrix. The modification had been undertaken by applying vinyltrymetoxysilane (VTMOS) that acted as a coupling agent to produce organophilic silica shell (SIMA). The shell is linked to the silica via reaction with the surface silanol group of the silica. The disappearance of methoxy groups in VTMOS was demonstrated by FTIR spectrum. The percentage of silica particles in UV curable hybrid formulation were varied on 5 %, 10 %, 15 %, 20 % and 25 wt % respectively. In this work, the formulation was applied on medium density fiber board (MDF) substrate and subsequent has been irradiated under UV light. Then, the coated MDF were characterized by several testing equipment (TGA, DSC, scratch tester, instron, SEM). From the result, we found that the addition of silica nanoparticles exhibit significant improvement in coating film properties as compared to film without silica nanoparticle includes significant improvement in its modulus and scratch resistance. This make them as promising coating candidate for MDF product. On the other hand, we also found that an increase of silica particle up to 25 wt %, the viscosity has increased rapidly indicates that it is not suitable for acrylate coating formulation due to disappearance of desired effect known as thixotropy. (Author)

  5. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. PMID:24433897

  6. Multi-walled carbon nanotubes/polymer composites in absence and presence of acrylic elastomer (ACM).

    Kumar, S; Rath, T; Mahaling, R N; Mukherjee, M; Khatua, B B; Das, C K

    2009-05-01

    Polyetherimide/Multiwall carbon nanotube (MWNTs) nanocomposites containing as-received and modified (COOH-MWNT) carbon nanotubes were prepared through melt process in extruder and then compression molded. Thermal properties of the composites were characterized by thermo-gravimetric analysis (TGA). Field emission scanning electron microscopy (FESEM) images showed that the MWNTs were well dispersed and formed an intimate contact with the polymer matrix without any agglomeration. However the incorporation of modified carbon nanotubes formed fascinating, highly crosslinked, and compact network structure throughout the polymer matrix. This showed the increased adhesion of PEI with modified MWNTs. Scanning electron microscopy (SEM) also showed high degree of dispersion of modified MWNTs along with broken ends. Dynamic mechanical analysis (DMA) results showed a marginal increase in storage modulus (E') and glass transition temperature (T(g)) with the addition of MWNTs. Increase in tensile strength and impact strength of composites confirmed the use the MWNTs as possible reinforcement agent. Both thermal and electrical conductivity of composites increased, but effect is more pronounced on modification due to formation of network of carbon nanotubes. Addition of acrylic elastomer to developed PEI/MWNTs (modified) nanocomposites resulted in the further increase in thermal and electrical properties due to the formation of additional bond between MWNTs and acrylic elastomers at the interface. All the results presented are well corroborated by SEM and FESEM studies. PMID:19452959

  7. Acrylic coatings exhibiting improved hardness, solvent resistance and glossiness by using silica nano-composites

    Dashtizadeh, Ahmad; Abdouss, Majid; Mahdavi, Hossein; Khorassani, Manuchehr

    2011-01-01

    To prepare nano-composite emulsion acrylic resins with improved surface hardness and solvent resistance, nano-silica particles were treated with surfactants. The monomers of methyl methacrylate/butylacrylate were co-polymerized on the surface of dispersed silica particles. Several emulsions with different silica contents and copolymer mole fractions were prepared. Finally the emulsions were modified to water-based acrylic coatings and improved properties such as surface hardness, solvent resistance and glossiness were determined. The study of coatings was directed to find the improved resin by optimum surface properties. Size distribution and morphology of latexes were characterized by Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. The glass transition temperature of nano-composites was measured and discussed its relation with silica contents, monomer mole fractions and improved properties of coatings. The optimum pendulum hardness of coatings was on 0.46 methyl methacrylate mole fraction and 120 g silica content. An increase in pendulum hardness of nano-composites with the addition of modified silica was observed. DLS and TEM studies indicate that silica particles were dispersed homogenously through the polymer matrix.

  8. Radiation-curing of acrylate composites including carbon fibres: A customized surface modification for improving mechanical performances

    Martin, Arnaud; Pietras-Ozga, Dorota; Ponsaud, Philippe; Kowandy, Christelle; Barczak, Mariusz; Defoort, Brigitte; Coqueret, Xavier

    2014-12-01

    The lower transverse mechanical properties of radiation-cured acrylate-based composites reinforced with carbon-fibre with respect to the thermosettable analogues was investigated from the viewpoint of chemical interactions at the interface between the matrix and the carbon material. XPS analysis of representative commercial carbon fibres revealed the presence of a significant amount of chemical functions potentially exerting an adverse effect on the initiation and propagation of the free radical polymerization initiated under high energy radiation. The EB-induced polymerization of n-butyl acrylate as a simple model monomer was conducted in the presence of various aromatic additives exhibiting a strong inhibiting effect, whereas thiols efficiently sensitize the initiation mechanism and undergo transfer reactions. A method based on the surface modification of sized fibres by thiomalic acid is proposed for overcoming the localized inhibition phenomenon and for improving the mechanical properties of the resulting acrylate-based composites.

  9. A Study on Effect of Surface Treatments on the Shear Bond Strength between Composite Resin and Acrylic Resin Denture Teeth

    Chatterjee, Nirmalya; Gupta, Tapas K.; Banerjee, Ardhendu

    2011-01-01

    Visible light-cured composite resins have become popular in prosthetic dentistry for the replacement of fractured/debonded denture teeth, making composite denture teeth on partial denture metal frameworks, esthetic modification of denture teeth to harmonize with the characteristics of adjacent natural teeth, remodelling of worn occlusal surfaces of posterior denture teeth etc. However, the researches published on the bond strength between VLC composite resins and acrylic resin denture teeth i...

  10. FTIR and morphology of liquid epoxidized natural rubber acrylate (LENRA)/silica hybrid composites

    Synthesis of organic-inorganic hybrid composites was carried out by combination of liquid epoxidized natural rubber acrylate (LENRA) and silica. Silica was introduce to the matrix by sol gel technique. The sol-gel technique was employed to prepare silica using tetraethyorthosilicate (TEOS) as precursor. HDDA and irga cure 184 were added to the formulations as reactive diluents and photosensitizer, respectively. The chemical modification was studied by Fourier Transform Infrared (FTIR) and energy dispersive X-ray analysis (EDAX). The morphological studies were conducted by the optical and scanning electron microscopes (SEM). It shows that silica was dispersed very well in the matrix for lower concentration of TEOS while agglomeration occurs at the higher concentration. The average particles size of silica were less than 100 nm. (Author)

  11. Synthesis of polyoxometalate-loaded epoxy composites

    Anderson, Benjamin J

    2014-10-07

    The synthesis of a polyoxometalate-loaded epoxy uses a one-step cure by applying an external stimulus to release the acid from the polyoxometalate and thereby catalyze the cure reaction of the epoxy resin. Such polyoxometalate-loaded epoxy composites afford the cured epoxy unique properties imparted by the intrinsic properties of the polyoxometalate. For example, polyoxometalate-loaded epoxy composites can be used as corrosion resistant epoxy coatings, for encapsulation of electronics with improved dielectric properties, and for structural applications with improved mechanical properties.

  12. Enhanced Dielectric Constant for Efficient Electromagnetic Shielding Based on Carbon-Nanotube-Added Styrene Acrylic Emulsion Based Composite

    Chen Changxin; Zhang Song; Ni Yuwei; Cai Seng; Huang Jie; Li Yong; Li Jiang-Tao

    2010-01-01

    Abstract An efficient electromagnetic shielding composite based on multiwalled carbon nanotubes (MWCNTs)-filled styrene acrylic emulsion-based polymer has been prepared in a water-based system. The MWCNTs were demonstrated to have an effect on the dielectric constants, which effectively enhance electromagnetic shielding efficiency (SE) of the composites. A low conductivity threshold of 0.23 wt% can be obtained. An EMI SE of ~28 dB was achieved for 20 wt% MWCNTs. The AC conductivity (σ ac...

  13. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites

    Song, Cunfeng [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chang, Ying; Cheng, Ling; Xu, Yiting [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Xiaoling, E-mail: tinachen0628@163.com [Department of Endodontics, Xiamen Stomatology Hospital, Teaching Hospital of Fujian Medical University, Xiamen 361003 (China); Zhang, Long; Zhong, Lina [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Dai, Lizong, E-mail: lzdai@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. - Highlights: • A new type of antibacterial agent (PSA/Ag-NPs nanocomposites) was synthesized. • The antibacterial activity against S. aureus and E. coli was studied. • Inhibition zone, MIC, MBC, and bactericidal kinetics were evaluated. • PSA/Ag-NPs nanocomposites showed excellent antibacterial activity.

  14. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. - Highlights: • A new type of antibacterial agent (PSA/Ag-NPs nanocomposites) was synthesized. • The antibacterial activity against S. aureus and E. coli was studied. • Inhibition zone, MIC, MBC, and bactericidal kinetics were evaluated. • PSA/Ag-NPs nanocomposites showed excellent antibacterial activity

  15. Factors influencing photo curing kinetics of novel UV-cured siloxane-modified acrylic coatings: Oxygen inhibition and composition

    Esposito Corcione, Carola, E-mail: carola.corcione@unile.it [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Lecce (Italy); Frigione, Mariaenrica [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Lecce (Italy)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer The inhibition effect of oxygen on the kinetic behaviour of photopolymerizable siloxane acrylic formulations was analyzed by thermal analysis. Black-Right-Pointing-Pointer The addition of a thiol in the mixtures allows to obtain higher conversion, to reduce the content of the UV initiator and to increase the T{sub g}. Black-Right-Pointing-Pointer The data found in air were fitted as a function of the presence of the thiol monomer obtaining a good agreement. - Abstract: An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings of stone substrates. The kinetics of the radical photopolymerization mechanism induced by UV radiations in presence of a suitable photoinitiator was studied by a calorimetric analysis by varying the atmosphere (oxygen or nitrogen) and the composition of the mixtures, in particular of the UV photoinitiator. The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free radical polymerization. The addition of a proper thiol to the acrylic modified resin was found to reduce the adverse effect of oxygen on the kinetic reaction and on the degree of conversion. This result allowed to reduce the content of the photoinitiator and to increase the content of the siloxane in the acrylic based mixtures. The effect of the change of the composition of the formulations on the kinetic behaviour of the acrylic based resins was also analysed by calorimetric analysis. Calorimetric experimental data were fitted to a simple kinetic model for radical photopolymerization reactions. Finally, a proper relationship between the glass transition temperature and the total extent of reaction was applied to the experimental data. A good agreement

  16. Factors influencing photo curing kinetics of novel UV-cured siloxane-modified acrylic coatings: Oxygen inhibition and composition

    Highlights: ► The inhibition effect of oxygen on the kinetic behaviour of photopolymerizable siloxane acrylic formulations was analyzed by thermal analysis. ► The addition of a thiol in the mixtures allows to obtain higher conversion, to reduce the content of the UV initiator and to increase the Tg. ► The data found in air were fitted as a function of the presence of the thiol monomer obtaining a good agreement. - Abstract: An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings of stone substrates. The kinetics of the radical photopolymerization mechanism induced by UV radiations in presence of a suitable photoinitiator was studied by a calorimetric analysis by varying the atmosphere (oxygen or nitrogen) and the composition of the mixtures, in particular of the UV photoinitiator. The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free radical polymerization. The addition of a proper thiol to the acrylic modified resin was found to reduce the adverse effect of oxygen on the kinetic reaction and on the degree of conversion. This result allowed to reduce the content of the photoinitiator and to increase the content of the siloxane in the acrylic based mixtures. The effect of the change of the composition of the formulations on the kinetic behaviour of the acrylic based resins was also analysed by calorimetric analysis. Calorimetric experimental data were fitted to a simple kinetic model for radical photopolymerization reactions. Finally, a proper relationship between the glass transition temperature and the total extent of reaction was applied to the experimental data. A good agreement between the experimental data and both the theoretical models was generally found.

  17. Design for cyclic loading endurance of composites

    Shiao, Michael C.; Murthy, Pappu L. N.; Chamis, Christos C.; Liaw, Leslie D. G.

    1993-12-01

    The application of the computer code IPACS (Integrated Probabilistic Assessment of Composite Structures) to aircraft wing type structures is described. The code performs a complete probabilistic analysis for composites taking into account the uncertainties in geometry, boundary conditions, material properties, laminate lay-ups, and loads. Results of the analysis are presented in terms of cumulative distribution functions (CDF) and probability density function (PDF) of the fatigue life of a wing type composite structure under different hygrothermal environments subjected to the random pressure. The sensitivity of the fatigue life to a number of critical structural/material variables is also computed from the analysis.

  18. Preparation and drug-loading properties of Fe{sub 3}O{sub 4}/Poly(styrene-co-acrylic acid) magnetic polymer nanocomposites

    Lu, Wensheng [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Coordination Chemistry Institute, School of Chemistry and Chemical Engineering and Life Science, Chaohu University, Chaohu 238000 (China); Shen, Yuhua, E-mail: s_yuhua@163.com [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Xie, Anjian [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Zhang, Weiqiang [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Coordination Chemistry Institute, School of Chemistry and Chemical Engineering and Life Science, Chaohu University, Chaohu 238000 (China)

    2013-11-15

    Fe{sub 3}O{sub 4}/poly(styrene-co-acrylic acid) magnetic polymer nanocomposites were synthesized by the dispersion polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe{sub 3}O{sub 4} nanoparticles modified with oleic acid as core, and poly(styrene-co-acrylic acid) as shell. Drug-loading properties of magnetic polymer nanocomposites with curcumin as a model drug were also studied. The results indicated that magnetic polymer nanocomposites with monodisperse were obtained, the particle size distribution was 50–120 nm, and the average size was about 100 nm. The contents of poly(styrene-co-acrylic acid) and Fe{sub 3}O{sub 4} nanoparticles in magnetic polymer nanocomposites were 74% and 24.7%, respectively. The drug-loading capacity and entrapment efficiency were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer nanocomposites at 300 K was 20.2 emu/g without coercivity and remanence. The as-prepared magnetic polymer nanocomposites have not only lots of functional carboxyl groups but also stronger magnetic response, which might have potential applications in drug carrier and targeted drug release.

  19. A drug-loaded gel based on polyelectrolyte complexes of poly (acrylic acid) with poly (vinylpyrrolidone) and chitosan

    A drug-loaded gel (CSPP) based on ionic crosslinked chitosan (CS) and polyelectrolyte complexes of poly (acrylic acid) (PAA) with poly (vinylpyrrolidone) (PVP) was prepared by dropping CS solution containing suitable amount of PVP into PAA and trisodium citrate co-existing gelling solution. The surface and cross-section morphology of the gel was observed using scanning electron microscopy, and the observation showed that the CSPP gel had more compact structure than CS gel. In vitro release profiles of model drug from the CSPP gel, which was prepared under different conditions, were investigated in simulative gastric fluid (pH 1.8) using an UV/vis spectrophotometer. The results showed that the rapid release of the model was restrained due to the complex of PVP and PAA, and the CSPP gel could serve as a suitable candidate in drug delivery system such as the site-specific controlled release of the drug in stomach. In addition, the release mechanism of drug was analyzed by fitting the amount of drug released into Peppa's potential equation.

  20. Thick composite structures under a load pinch

    Karama, Moussa

    2015-01-01

    Thick composites are increasingly used in the design of mechanical structures. Combined with low weight, they are generally resistant structures, which can support importante loads. In addition, depending on the number and nature of the materials used, it is possible to adapt properties for specific applications (damping structures).This work proposes the establishment of a new theoretical model of multilayer beam. The model, which is simple and easy handling, is intended for the subsequent e...

  1. Synthesis of linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(Ⅱ) from aqueous solutions

    Maryam Irani; Hanafi Ismail; Zulkifli Ahmad; Maohong Fan

    2015-01-01

    The purpose of this work is to remove Pb(Ⅱ) from the aqueous solution using a type of hydrogel composite.A hydrogel composite consisting of waste linear low density polyethylene,acrylic acid,starch,and organo-montmorillonite was prepared through emulsion polymerization method.Fourier transform infrared spectroscopy (FTIR),Solid carbon nuclear magnetic resonance spectroscopy (CNMR)),silicon-29 nuclear magnetic resonance spectroscopy (Si NMR)),and X-ray diffraction spectroscope ((XRD) were applied to characterize the hydrogel composite.The hydrogel composite was then employed as an adsorbent for the removal of Pb(Ⅱ) from the aqueous solution.The Pb(Ⅱ)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy (FTIR)),scanning electron microscopy (SEM)),and X-ray photoelectron spectroscopy ((XPS)).From XPS results,it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(Ⅱ).Kinetic studies indicated that the adsorption of Pb(Ⅱ)followed the pseudo-second-order equation.It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm.The maximum removal capacity of the hydrogel composite for Pb(Ⅱ) ions was 430 mg/g.Thus,the waste linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(Ⅱ) adsorbent.

  2. Enhanced dielectric constant for efficient electromagnetic shielding based on carbon-nanotube-added styrene acrylic emulsion based composite.

    Li, Yong; Chen, Changxin; Li, Jiang-Tao; Zhang, Song; Ni, Yuwei; Cai, Seng; Huang, Jie

    2010-01-01

    An efficient electromagnetic shielding composite based on multiwalled carbon nanotubes (MWCNTs)-filled styrene acrylic emulsion-based polymer has been prepared in a water-based system. The MWCNTs were demonstrated to have an effect on the dielectric constants, which effectively enhance electromagnetic shielding efficiency (SE) of the composites. A low conductivity threshold of 0.23 wt% can be obtained. An EMI SE of ~28 dB was achieved for 20 wt% MWCNTs. The AC conductivity (σac) of the composites, deduced from imaginary permittivity, was used to estimate the SE of the composites in X band (8.2-12.4 GHz), showing a good agreement with the measured results. PMID:20596498

  3. Enhanced Dielectric Constant for Efficient Electromagnetic Shielding Based on Carbon-Nanotube-Added Styrene Acrylic Emulsion Based Composite

    Chen Changxin

    2010-01-01

    Full Text Available Abstract An efficient electromagnetic shielding composite based on multiwalled carbon nanotubes (MWCNTs-filled styrene acrylic emulsion-based polymer has been prepared in a water-based system. The MWCNTs were demonstrated to have an effect on the dielectric constants, which effectively enhance electromagnetic shielding efficiency (SE of the composites. A low conductivity threshold of 0.23 wt% can be obtained. An EMI SE of ~28 dB was achieved for 20 wt% MWCNTs. The AC conductivity (σ ac of the composites, deduced from imaginary permittivity, was used to estimate the SE of the composites in X band (8.2–12.4 GHz, showing a good agreement with the measured results.

  4. Behavior of Composite Columns Subjected to Lateral Cyclic Loading

    AL-Bdoor, Mazen

    2013-01-01

    ABSTRACT: Nonlinear 3-D finite element models were developed to investigate the cumulative damage of composite columns subjected to cyclic loading by comparing the effects of different levels of axial loads on the cyclic capacity of steel, reinforced concrete, and composite beam-columns. The beam-column specimens were modeled as fixed cantilever beam-columns with an axial load level of 10%, 15%, and 20% of their axial load capacity as well as cyclic loading similar to that suggested ...

  5. Synthesis and urea-loading of an eco-friendly superabsorbent composite based on mulberry branches

    Xiying Liang

    2013-02-01

    Full Text Available Mulberry branch, consisting of bark and stalk, was used as raw skeleton material without any chemical pre-treatment to synthesize an eco-friendly mulberry branch-g-poly(acrylic acid-co-acrylamide (PMB/P(AA-co-AM superabsorbent composite. The synthesis conditions and properties of the PMB/P(AA-co-AM superabsorbent composite were investigated. The results showed that under the optimal synthesis conditions, the water absorbency of the prepared PMB/P(AA-co-AM reached 570.5 g/g in deionized water, 288.0 g/g in tap water, and 70.0 g/g in 0.9 wt% aqueous NaCl solution. The PMB/P(AA-co-AM composite also exhibited excellent water retention capacity as well as a rapid water absorbency rate. The urea loading percentage of the PMB/P(AA-co-AM composite was controlled by the concentration of aqueous urea solution. The release of urea from the loaded PMB/P(AA-co-AM composite in deionized water initially exhibited a high rate of release for 60 min, followed by a rapid decline. Meanwhile, the PMB/P(AA-co-AM superabsorbent composite with larger particle size achieved a better sustained release of urea.

  6. Influence of Methacrylic-Acrylic Copolymer Composition on Plasticiser-free Optode Films for pH Sensors

    Musa Ahmad

    2003-03-01

    Full Text Available In this work we have examined the use of plasticiser-free polymeric films incorporating a proton selective chromoionophore for optical pH sensor. Four types of methacrylic-acrylic copolymers containing different compositions of n-butyl acrylate (nBA and methyl methacrylate (MMA were synthesised for use as optical sensor films. The copolymers were mixed with appropriate amounts of chromoionophore (ETH5294 and a lipophilic salt before spin coated on glass slides to form films for the evaluation of pH response using spectrophotometry. Co-polymer films with high nBA content gave good response and the response time depended on the film thickness. A preliminary evaluation of the optical films of high nBA content with pHs from 2 - 14 showed distinguishable responses from pH 5 - 9. However, the adhesion of the pH sensitive film was good for copolymers with higher content of MMA but not for films with high nBA.

  7. Calcium Phosphate Mineralization in Cellulose Derivative/Poly(acrylic acid) Composites Having a Chiral Nematic Mesomorphic Structure.

    Ogiwara, Takuya; Katsumura, Ayaka; Sugimura, Kazuki; Teramoto, Yoshikuni; Nishio, Yoshiyuki

    2015-12-14

    Calcium phosphate mineralization was conducted by using polymer composites of liquid-crystalline (ethyl)cellulose (EC) or (hydroxypropyl)cellulose (HPC) with poly(acrylic acid) (PAA) as a scaffolding medium for the inorganic deposition. The EC/PAA and HPC/PAA samples were prepared in colored film form from EC and HPC lyotropic liquid crystals of left-handed and right-handed chiral nematics, respectively, by polymerization and cross-linking of acrylic acid as the main solvent component. The mineralization was allowed to proceed in a batchwise operation by soaking the liquid-crystalline films in an aqueous salt solution containing the relevant ions, Ca(2+) and HPO4(2-). The calcium phosphate-deposited EC/PAA and HPC/PAA composites (weight gain, typically 15-25% and 6-11%, respectively) retained the chiral nematic organization of the respective original handedness but exhibited selective light-reflection of longer wavelengths relative to that of the corresponding nonmineralized samples. From X-ray diffraction and energy-dispersive X-ray spectroscopy measurements, it was deduced that the calcium and phosphorus were incorporated inside the polymer matrices in three forms: amorphous calcium phosphate, hydroxyapatite, and a certain complex of PAA-Ca(2+). Dynamic mechanical analysis and thermogravimetry revealed that the inorganic hybridization remarkably enhanced the thermal and mechanical performance of the optically functionalized cellulosic/synthetic polymer composites; however, the effect was more drastic in the EC/PAA series rather than the HPC/PAA series, reflecting the difference in the deposited mineral amount between the two. PMID:26536381

  8. Adsorptive features of poli(acrylic acid-co-hydroxyapatite) composite for UO22+

    The copolymer of poli(acrylic acid-co-hydroxyapatite) (PAA-HAP) was prepared and characterized by means of FT-IR and SEM analysis. The adsorptive features of PAA-HAP for UO22+ was studied as a function of pH, adsorbent dosage, initial metal ion concentration and temperature. The adsorption isotherm data fitted well to the Langmuir isotherm model. The adsorbed UO22+ can be desorbed effectively by 0.1 M HNO3. The maximum adsorption capacities for UO22+ of the dry PAA-HAP was 1.86 x 10-4 mol/g. The high adsorption capacity and kinetics results indicate that PAA-HAP can be used as an alternative adsorbent to remove UO22+ from aqueous solution. (author)

  9. Electron-beam initiated polymerization of acrylate compositions 1 : FTIR monitoring of incremental irradiation

    Patacz, C; Coqueret, X

    2000-01-01

    The electron-beam induced polymerization of some representative formulations including acrylate functional oligomers and diluents has been investigated by means of FTIR spectroscopy applied to films that were cured under a nitrogen flow. In order to gain a deeper insight into the reactivity of the polymerizable systems, the conversion-dose relationship was examined with emphasis on the following points : depth cure profile of the films, and the additivity of effects of incremental radiation doses on monomer conversion. It was shown to be possible to reproduce the actual polymerization profile from discontinuous measurements. This remarkable result is tentatively explained by the geometry of the samples causing limited thermal effects and by the minor influence of possible inhibition and post-polymerization that could influence each of the incremental transformations compared to a single large dose treatment. This method provides a fine tool for revealing differences in kinetic behavior between polymerizable m...

  10. Effect of Molecular Weight on the Properties of Liquid Epoxidized Natural Rubber Acrylate (LENRA)/ Silica Hybrid Composites

    This paper reports on the effect of molecular weight on the morphological and mechanical properties of liquid epoxidized natural rubber acrylate (LENRA)/ silica hybrid composites prepared by sol-gel technique. The sol-gel reaction was conducted at different concentration of tetraethyl orthosilicate (TEOS), used as a precursor of silica. TEOS were introduced in 10, 20, 30, 40 and 50 parts per hundred rubber (phr) in the composites. Two different molecular weights of ENR were used to study the effect of molecular weight on the mechanical and morphological properties of the compounds. These compounds were cured by ultraviolet (UV) irradiation. The mechanical properties were studied through pendulum hardness and scratch tests. Higher molecular weight of ENR showed better mechanical properties than lower molecular weight. Transmission electron microscope was used to determine the silica size and to study the distribution and dispersion of the silica particles. High molecular weight showed greater distribution and dispersion of silica particles with diameter of 13 - 256 nm. Morphological and mechanical properties of LENRA/ silica hybrid composites were improved by using high molecular weight of ENR. (author)

  11. Predicting the Structural Performance of Composite Structures Under Cyclic Loading

    Kassapoglou, C.

    2012-01-01

    The increased use of advanced composite materials on primary aircraft structure has brought back to the forefront the question of how such structures perform under repeated loading. In particular, when damage or other stress risers are present, tests have shown that the load to cause failure after a given number of cycles is a decreasing function of these cycles. This is a result of damage that was already present in the structure or was created during cyclic loading. In composites, multiple ...

  12. Precise 3D printing of micro/nanostructures using highly conductive carbon nanotube-thiol-acrylate composites

    Liu, Y.; Xiong, W.; Jiang, L. J.; Zhou, Y. S.; Lu, Y. F.

    2016-04-01

    Two-photon polymerization (TPP) is of increasing interest due to its unique combination of truly three-dimensional (3D) fabrication capability and ultrahigh spatial resolution of ~40 nm. However, the stringent requirements of non-linear resins seriously limit the material functionality of 3D printing via TPP. Precise fabrication of 3D micro/nanostructures with multi-functionalities such as high electrical conductivity and mechanical strength is still a long-standing challenge. In this work, TPP fabrication of arbitrary 3D micro/nanostructures using multi-walled carbon nanotube (MWNT)-thiolacrylate (MTA) composite resins has been developed. Up to 0.2 wt% MWNTs have been incorporated into thiol-acrylate resins to form highly stable and uniform composite photoresists without obvious degradation for one week at room temperature. Various functional 3D micro/nanostructures including woodpiles, micro-coils, spiral-like photonic crystals, suspended micro-bridges, micro-gears and complex micro-cars have been successfully fabricated. The MTA composite resin offers significant enhancements in electrical conductivity and mechanical strength, and on the same time, preserving high optical transmittance and flexibility. Tightly controlled alignment of MWNTs and the strong anisotropy effect were confirmed. Microelectronic devices including capacitors and resistors made of the MTA composite polymer were demonstrated. The 3D micro/nanofabrication using the MTA composite resins enables the precise 3D printing of micro/nanostructures of high electrical conductivity and mechanical strength, which is expected to lead a wide range of device applications, including micro/nano-electromechanical systems (MEMS/NEMS), integrated photonics and 3D electronics.

  13. Effect of silver-supported materials on the mechanical and antibacterial properties of reinforced acrylic resin composites

    Highlights: • The novel Novaron-nano-ZrO2–ABW/PMMA composites was synthesized. • Nano-ZrO2 and ABWs could increase the mechanical behavior of this composites. • Novaron had synergistic effect to improve the composites mechanical property and the 4 wt% was the optimal proportion. • Novaron could improve the antibacterial properties through their direct contact with the bacteria. • The composites did not have an adverse affect on cell viability. - Abstract: The aim of this study was to investigate the effect of silver-supported material (Novaron (N)) in acrylic resin (poly(methyl methacrylate) (PMMA)) composites, which reinforced with zirconium dioxide nanoparticles (nano-ZrO2) and aluminum borate whiskers (ABWs), on the mechanical behavior, antibacterial properties and cytotoxicity. Silanized ABWs (4 wt%) and nano-ZrO2 (2 wt%) were mixed with PMMA powder to obtain nano-ZrO2–ABW/PMMA matrices. Various amounts of Novaron particles were incorporated into the matrices and the pure PMMA to test the flexural strength. In addition, Streptococcus mutans (S. mutans) and Canidia albicans (C. albicans) biofilms on the specimen surface and in the culture medium were investigated for metabolic activity and colony-forming units (CFUs). Extracts taken in the cell culture medium of the specimens were used to evaluate cell viability. Results showed that the silanized nano-ZrO2 and ABWs could improve the flexural strength of composites compared with the pure PMMA. Novaron itself had no mechanical function for composites while it had synergistic effect when it mixed with silanized nano-ZrO2 and ABWs. And when 4 wt% (N-4) Novaron mixed in nano-ZrO2–ABW/PMMA composites, flexural strength achieved an increase of 44%, getting the maximum value. For the antibacterial properties, the values of MTT and CFUs of S. mutans and C. albicans biofilms on the composites surface were greatly reduced (p < 0.05) with the higher proportion of Novaron, and no significant difference was

  14. Polymer composite material structures comprising carbon based conductive loads

    Jérôme, Robert; Pagnoulle, Christophe; Detrembleur, Christophe; Thomassin, Jean-Michel; Huynen, Isabelle; Bailly, Christian; Bednarz, Lucasz; Daussin, Raphaël; Saib, Aimad

    2006-01-01

    The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 to 6 wt% carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loads. Th...

  15. STUDY OF COMPOSITE MEMBRANE OF CELLULOSE ACETATE OR POLYVINYL ALCOHOL BLENDED WITH METHYLMETHACRYLATE-ACRYLIC ACID COPOLYMER FOR PERVAPORATION SEPARATION

    Huan-lin Chen; Jun Tan; Mo-e Liu; Chang-luo Zhu

    1999-01-01

    In this paper, methylmethacrylate-acrylic acid MMA-AA hydrophilic and hydrophobic copolymers were prepared by copolymerization for preparing membrane materials. The composite membrane of cellulose acetate (CA) blended with MMA-AA hydrophobic copolymer was used for the separation of methanol from pentane-methanol mixture. When the methanol concentration was only 1 wt%, the permeate flux still maintained at 350 g/m2h and separation factor was as big as 800. The composite membrane of PVA (polyvinyl alcohol) blended with MMA-AA hydrophilic copolymer was used for the separation of ethanolwater mixture. The permeate flux was increased to 975 g/m2h at 74℃ and the separation factor reached 3000at 25℃. The PVA/MMA-AA blended membrane surface modified by ammonia plasma was also investigated for separating ethanol-water mixture. Both permeate flux and separation factor of the membrane was improved. However, there was no obvious difference of plasma treatment time in the interval of 20~40 min.

  16. Electroactive behavior assessment of poly(acrylic acid)-graphene oxide composite hydrogel in the detection of cadmium

    Bejarano-Jimenez, A.; Escobar-Barrios, V.A.; Kleijn, J.M.; Oritz-Ledon, C.A.; Chazaro-Ruiz, L.F.

    2014-01-01

    Super absorbent polymers of acrylic acid-graphene oxide (PAA-GO) were synthesized with different percentage of chemical neutralization (0, 10, and 20%) of the acrylic acid monomer before its polymerization. The influence of their swelling and adsorption/desorption capacity of cadmium ions in aqueous

  17. Fracture mechanics and statistical modeling of ternary blends of polylactide/ethylene-acrylate copolymer /wood-flour composites

    Afrifah, Kojo Agyapong

    This study examined the mechanisms of toughening the brittle bio-based poly(lactic acid) (PLA) with a biodegradable rubbery impact modifier to develop biodegradable and cost effective PLA/wood-flour composites with improved impact strength, toughness, high ductility, and flexibility. Semicrystalline and amorphous PLA grades were impact modified by melt blending with an ethylene-acrylate copolymer (EAC) impact modifier. EAC content was varied to study the effectiveness and efficiency of the impact modifier in toughening the semicrystalline and amorphous grades of the PLA. Impact strength was used to assess the effectiveness and efficiency of the EAC in toughening the blends, whereas the toughening mechanisms were determined with the phase morphologies and the miscibilities of the blends. Subsequent tensile property analyses were performed on the most efficiently toughened PLA grade. Composites were made from PLA, wood flour of various particle sizes, and EAC. Using two-level factorial design the interaction between wood flour content, wood flour particle size, and EAC content and its effect on the mechanical properties of the PLA/wood-flour composites was statistically studied. Numerical optimization was also performed to statistically model and optimize material compositions to attain mechanical properties for the PLA/wood-flour composites equivalent to at least those of unfilled PLA. The J-integral method of fracture mechanics was applied to assess the crack initiation (Jin) and complete fracture (J f) energies of the composites to account for imperfections in the composites and generate data useful for engineering designs. Morphologies of the fractured surfaces of the composites were analyzed to elucidate the failure and toughening mechanisms of the composites. The EAC impact modifier effectively improved the impact strength of the PLA/EAC blends, regardless of the PLA type. However, the EAC was more efficient in the semicrystalline grades of PLA compared to the

  18. Acrylic vessel cleaning tests

    The acrylic vessel as constructed is dirty. The dirt includes blue tape, Al tape, grease pencil, gemak, the glue or residue form these tapes, finger prints and dust of an unknown composition but probably mostly acrylic dust. This dirt has to be removed and once removed, the vessel has to be kept clean or at least to be easily cleanable at some future stage when access becomes much more difficult. The authors report on the results of a series of tests designed: (a) to prepare typical dirty samples of acrylic; (b) to remove dirt stuck to the acrylic surface; and (c) to measure the optical quality and Th concentration after cleaning. Specifications of the vessel call for very low levels of Th which could come from tape residues, the grease pencil, or other sources of dirt. This report does not address the concerns of how to keep the vessel clean after an initial cleaning and during the removal of the scaffolding. Alconox is recommended as the cleaner of choice. This acrylic vessel will be used in the Sudbury Neutrino Observatory

  19. Preparation of mesoporous poly (acrylic acid)/SiO2 composite nanofiber membranes having adsorption capacity for indigo carmine dye

    Xu, Ran; Jia, Min; Li, Fengting; Wang, Hongtao; Zhang, Bingru; Qiao, Junlian

    2012-03-01

    Mesoporous poly (acrylic acid)/SiO2 (PAA/SiO2) composite nanofiber membranes functionalized with mercapto groups were fabricated by a sol-gel electrospinning method, and their adsorption capacity for indigo carmine was investigated. The membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, x-ray powder diffraction (XRD), and nitrogen adsorption-desorption measurement. SEM and TEM observation results showed that the PAA/SiO2 fibers had diameters between 400-800 nm and mesopores with an average pore size of 3.88 nm. The specific surface area of the mesoporous nanofiber membranes was 514.89 m2/g. The characteristic peaks for mercapto group vibration in FTIR and Raman spectra demonstrated that the mercapto groups have been incorporated into the silica skeleton. The adsorption isotherm data of indigo carmine on the membranes fit well with Redlich-Peterson model, and the maximum adsorption capacity calculated was 523.11 mg/g. It was found that the removal rate of indigo carmine by the membranes reached a maximum of 98% in 90 min and the adsorption kinetics followed a pseudo-second-order model. The high adsorption capacity of PAA/SiO2 nanofiber membrane makes it a promising adsorbent for indigo carmine removal from the wastewater.

  20. Behavior of slender steel concrete composite columns in eccentric loading

    ZHAO Gen-tian; ZHANG Meng-xi; LI Yong-he

    2009-01-01

    Ten slender steel reinforced cencrete (SRC) composite columns are tested under eccentric loading conditions.Effects of concrete strength, slenderness of columns and eccentricity of the axial load are studied. The load-carrying capacity is reduced with increased slenderness ratio and eccentricity. Concrete strength has no obvious influence on eccentrically loaded columns. Then, a nonlinear numerical method of pin-ended slender columns is also presented. This method is applicable for determining the material failure load or buckling failure load of a slender steel reinforced concrete composite column. In this method both material and geometric nonlinearities are taken into account. The results of numerical analysis accord well with the test results. The test results are also compared with the results predicted by ACI318-05 and the China Specifications.

  1. Thermal and mechanical properties of palm oil-based polyurethane acrylate/ clay nano composites prepared by in-situ intercalative method and electron beam radiation

    Full-text: Palm oil based-polyurethane acrylate (POBUA)/ clay nano composites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5 % wt), and then subjected to polycondensation reaction with MDI. Nano composites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nano clay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Angstrom, while the structure morphology of the nano composites was investigated by TEM and SEM. The nano composites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nano composites was significantly increased by incorporation of nano clay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nano composites. Tensile strength and Young's modulus of the nano composites showed remarkable improvement compared to the neat POBUA. (author)

  2. Culture-Loaded Expressions in Korean EFL Students' Compositions.

    Choe, Yongjae Paul

    2001-01-01

    Discusses the inevitability of native culture-loaded expressions in Korean English-as-a-Foreign-Language students' compositions. Cultures, both native and target play a major role in forming ideas in any communicative situation. Thus, Korean EFL students' compositions all reveal without exception the traits of Korean culture. (Author/VWL)

  3. Polymer composite material structures comprising carbon based conductive loads

    Jérôme, Robert; Pagnoulle, Christophe; Detrembleur, Christophe; Thomassin, Jean-Michel; Huynen, Isabelle; Bailly, Christian; Bednarz, Luikasz; Daussin, Raphaël; Saib, Aimad; Baudouin, Anne-Christine; Laloyaux, Xavier

    2007-01-01

    The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 wt % to 6 wt % carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loa...

  4. Impact Loading of Composite and Sandwich Structures

    Kazemahvazi, Sohrab

    2010-01-01

    Low weight is one of the most important factors in the design process of high speed naval ships, road vehicles and aircrafts. Lower structural weight enables the possibility of down-sizing the propulsion system and thus decrease manufacturing and operating costs as well as reducing the environmental impact. Two efficient ways of reducing the structural weight of a structure is by using high performance composite materials and by using geometrically efficient structures such as the sandwich co...

  5. Effect of chemical composition on corneal tissue response to photopolymerized materials comprising 2-hydroxyethyl methacrylate and acrylic acid

    The purpose of this work was to investigate the relationship between the feed composition of 2-hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc) and hydrogel material compatibility towards ocular anterior segment tissues, particularly the corneal endothelium. The monomer solutions of HEMA and AAc were mixed at varying volume ratios of 92:0, 87:5, 82:10, 77:15, and 72:20, and were subjected to UV irradiation. Then, the 7-mm-diameter membrane implants made from photopolymerized materials were placed into the ocular anterior chamber for 4 days and assessed by biomicroscopic examinations, corneal thickness measurements, and quantitative real-time reverse transcription polymerase chain reaction analyses. The poly(HEMA-co-AAc) implants prepared from the solution mixture containing 0–10 vol.% AAc displayed good biocompatibility. However, with increasing volume ratio of AAc and HEMA from 15:77 to 20:72, the enhanced inflammatory response, decreased endothelial cell density, and increased ocular score and corneal thickness were observed, probably due to the influence of surface charge of copolymer membranes. On the other hand, the ionic pump function of corneal endothelium exposed to photopolymerized membranes was examined by analyzing the Na+,K+-ATPase alpha 1 subunit (ATP1A1) expression level. The presence of the implants having higher amount of AAc incorporated in the copolymers (i.e., 15.1 to 24.7 μmol) and zeta potential (i.e., -38.6 to − 56.5 mV) may lead to abnormal transmembrane transport. It is concluded that the chemical composition of HEMA/AAc has an important influence on the corneal tissue responses to polymeric biomaterials. - Highlights: • We examine the corneal tissue responses to photopolymerized biomaterials. • Carboxyl groups in copolymers increased with increasing volume ratio of AAc/HEMA. • 15–20 vol.% AAc raised ocular score and caused corneal endothelial loss and edema. • High anionic charge density stimulated inflammation and

  6. Effect of chemical composition on corneal cellular response to photopolymerized materials comprising 2-hydroxyethyl methacrylate and acrylic acid

    Characterization of corneal cellular response to hydrogel materials is an important issue in ophthalmic applications. In this study, we aimed to investigate the relationship between the feed composition of 2-hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc) and material compatibility towards corneal stromal and endothelial cells. The monomer solutions of HEMA and AAc were mixed at varying volume ratios of 92:0, 87:5, 82:10, 77:15, and 72:20, and were subjected to UV irradiation. Results of electrokinetic measurements showed that an increase in absolute zeta potential of photopolymerized membranes is observed with increasing the volume ratios of AAc/HEMA. Following 4 days of incubation with various hydrogels, the primary rabbit corneal stromal and endothelial cell cultures were examined for viability, proliferation, and pro-inflammatory gene expression. The samples prepared from the solution mixture containing 0–10 vol.% AAc displayed good cytocompatibility. However, with increasing volume ratio of AAc and HEMA from 15:77 to 20:72, the decreased viability, inhibited proliferation, and stimulated inflammation were noted in both cell types, probably due to the stronger charge–charge interactions. On the other hand, the ionic pump function of corneal endothelial cells exposed to photopolymerized membranes was examined by analyzing the Na+,K+-ATPase alpha 1 subunit (ATP1A1) expression level. The presence of material samples having higher anionic charge density (i.e., zeta potential of − 38 to − 56 mV) may lead to abnormal transmembrane transport. It is concluded that the chemical composition of HEMA/AAc has an important influence on the corneal stromal and endothelial cell responses to polymeric biomaterials. - Highlights: • We examine the corneal cellular responses to photopolymerized biomaterials. • Charge density of membranes was increased with increasing volume ratio of AAc/HEMA. • 15–20 vol.% AAc decreased viability and proliferation of all

  7. Effect of chemical composition on corneal tissue response to photopolymerized materials comprising 2-hydroxyethyl methacrylate and acrylic acid

    Lai, Jui-Yang, E-mail: jylai@mail.cgu.edu.tw

    2014-01-01

    The purpose of this work was to investigate the relationship between the feed composition of 2-hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc) and hydrogel material compatibility towards ocular anterior segment tissues, particularly the corneal endothelium. The monomer solutions of HEMA and AAc were mixed at varying volume ratios of 92:0, 87:5, 82:10, 77:15, and 72:20, and were subjected to UV irradiation. Then, the 7-mm-diameter membrane implants made from photopolymerized materials were placed into the ocular anterior chamber for 4 days and assessed by biomicroscopic examinations, corneal thickness measurements, and quantitative real-time reverse transcription polymerase chain reaction analyses. The poly(HEMA-co-AAc) implants prepared from the solution mixture containing 0–10 vol.% AAc displayed good biocompatibility. However, with increasing volume ratio of AAc and HEMA from 15:77 to 20:72, the enhanced inflammatory response, decreased endothelial cell density, and increased ocular score and corneal thickness were observed, probably due to the influence of surface charge of copolymer membranes. On the other hand, the ionic pump function of corneal endothelium exposed to photopolymerized membranes was examined by analyzing the Na{sup +},K{sup +}-ATPase alpha 1 subunit (ATP1A1) expression level. The presence of the implants having higher amount of AAc incorporated in the copolymers (i.e., 15.1 to 24.7 μmol) and zeta potential (i.e., -38.6 to − 56.5 mV) may lead to abnormal transmembrane transport. It is concluded that the chemical composition of HEMA/AAc has an important influence on the corneal tissue responses to polymeric biomaterials. - Highlights: • We examine the corneal tissue responses to photopolymerized biomaterials. • Carboxyl groups in copolymers increased with increasing volume ratio of AAc/HEMA. • 15–20 vol.% AAc raised ocular score and caused corneal endothelial loss and edema. • High anionic charge density stimulated inflammation

  8. Effect of chemical composition on corneal cellular response to photopolymerized materials comprising 2-hydroxyethyl methacrylate and acrylic acid

    Lai, Jui-Yang, E-mail: jylai@mail.cgu.edu.tw

    2013-10-15

    Characterization of corneal cellular response to hydrogel materials is an important issue in ophthalmic applications. In this study, we aimed to investigate the relationship between the feed composition of 2-hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc) and material compatibility towards corneal stromal and endothelial cells. The monomer solutions of HEMA and AAc were mixed at varying volume ratios of 92:0, 87:5, 82:10, 77:15, and 72:20, and were subjected to UV irradiation. Results of electrokinetic measurements showed that an increase in absolute zeta potential of photopolymerized membranes is observed with increasing the volume ratios of AAc/HEMA. Following 4 days of incubation with various hydrogels, the primary rabbit corneal stromal and endothelial cell cultures were examined for viability, proliferation, and pro-inflammatory gene expression. The samples prepared from the solution mixture containing 0–10 vol.% AAc displayed good cytocompatibility. However, with increasing volume ratio of AAc and HEMA from 15:77 to 20:72, the decreased viability, inhibited proliferation, and stimulated inflammation were noted in both cell types, probably due to the stronger charge–charge interactions. On the other hand, the ionic pump function of corneal endothelial cells exposed to photopolymerized membranes was examined by analyzing the Na{sup +},K{sup +}-ATPase alpha 1 subunit (ATP1A1) expression level. The presence of material samples having higher anionic charge density (i.e., zeta potential of − 38 to − 56 mV) may lead to abnormal transmembrane transport. It is concluded that the chemical composition of HEMA/AAc has an important influence on the corneal stromal and endothelial cell responses to polymeric biomaterials. - Highlights: • We examine the corneal cellular responses to photopolymerized biomaterials. • Charge density of membranes was increased with increasing volume ratio of AAc/HEMA. • 15–20 vol.% AAc decreased viability and proliferation

  9. Lead titanate/cyclic carbonate dependence on ionic conductivity of ferro/acrylate blend polymer composites

    Jayaraman, R.; Vickraman, P.; Subramanian, N. M. V.; Justin, A. Simon

    2016-05-01

    Impedance, XRD, DSC and FTIR studies had been carried out for PVdF-co-HFP/LIBETI based system for three plasticizer (EC/DMC) - filler (PbTiO3) weight ratios. The enhanced conductivity 4.18 × 10-5 Scm-1 was noted for 57.5 wt% -7.5 wt% plasticizer - filler. while blending PEMA to PVdF-co-HFP respectively 7.5: 22.5 wt % (3/7), 15 wt%: 15 wt % (5/5) and 22.5wt %: 7.5 wt % (7/3), the improved conductivity was noted for 3/7 ratio 1.22 × 10-5 S cm-1 and its temperature dependence abide Arrhenius behavior. The intensity of peaks in XRD diffractogram registered dominance of lead titanate, from 2θ = 10° to 80° and absence of VdF crystallites (α+β phase) was noted. In DSC studies, the presence of the exotherm events, filler effect was distinctively seen exhibiting recrystallization of VdF crystallites. In blending PEMA, however, no trace of exotherms was found suggestive of PEMA better inhibiting recrystallization. FTIR study confirmed molecular interactions of various constituents in the vibrational band 500 - 1000 cm-1 both in pristine PVdF-co-HFP and PEMA blended composites with reference to C-F stretching, C-H stretching and C=O carbonyl bands.

  10. Fatigue Life Prediction of Composite Under Two Block Loading

    M. Bendouba

    2014-02-01

    Full Text Available The damage evolution mechanism is one of the important focuses of fatigue behaviour investigation of composite materials and also the foundation to predict fatigue life of composite structures for engineering applications. This paper is dedicated to damage investigation of composite materials under two block loading cycle fatigue conditions. The loading sequence effect and the influence of the cycle ratio of the first stage on the cumulative fatigue life are studied. Two loading sequences, i.e., high-to-low and low-to-high cases are considered. The proposed damage indicator is connected cycle by cycle to the S-N curve and the experimental results are in agreement with model expectations. Previous experimental research is employed for validation.

  11. Study on Crosslinkable Urethane/Styrene-acrylic Polymer Composite Emulsion%交联型聚氨酯/苯丙树脂复合乳液的研究

    2001-01-01

    The Crosslinkable polyurethane/styrene-acrylic polymer composite emulsion was obtained by mixing the styrene-acrylic polymer emulsion incorporating DAAM with the polyurethane dispersion con taining hydrazine group. The influence of the amount of DAAM on styrene-acrylic polymer emulsion was studied. The crosslinking reaction between keto group and hydrazine group was proved by FTIR and TEM (transimission electron microscope) technology. Studies on the film properties show that water-resistance, solvent-resistance, tensile strength and elongation at break of the emulsion film were all improved due to the crosslinking reaction.%将双丙酮丙烯酰胺(DAAM)参与共聚的苯丙乳液与含有肼基的聚氨酯水分散体混合后,得到了交联型聚氨酯/苯丙树脂复合乳液。研究了DAAM的用量对苯丙乳液的影响。用傅里叶红外光谱和透射电镜证实了酮羰基与肼基之间发生了交联反应。对乳液膜性能的研究结果表明,交联反应提高了乳液膜的耐水性、耐溶剂性、断裂强度、断裂伸长率。

  12. Analysis of Load Test on Composite I-Girder Bridge

    Huseynov, F.; Brownjohn, J. M. W.; O'Brien, Eugene J.; Hester, David

    2016-01-01

    This paper showcases the importance of field testing in efforts to deal with the deteriorating infrastructure. It demonstrates a load test performed on a healthy but aging composite reinforced concrete bridges in Exeter, UK. The bridge girders were instrumented with strain transducers and static strains were recorded while a four-axle, 32 tonne lorry remained stationary in a single lane. The results obtained from the field test were used to calculate transverse load distribution factors (DFs)...

  13. Tetracycline Loaded Collagen/Hydroxyapatite Composite Materials for Biomedical Applications

    Laura Cristina Rusu

    2015-01-01

    Full Text Available The paper describes the preparation, characterisation, and testing of tetracycline loaded collagen-carboxymethylcellulose/hydroxyapatite ternary composite materials. The synthesis of this drug delivery system consists in two steps: the first step is the mineralization of collagen-carboxymethylcellulose gel while the second step corresponds to the loading of the ternary composite material with tetracycline. The obtained DDS is characterised by physicochemical, morphological, and release behaviour by using FTIR spectroscopy and microscopy, scanning electron microscopy, and UV-VIS spectroscopy. Based on the release study, it can be assumed that tetracycline is released in a prolonged way, assuring at least 6 days of antiseptic properties.

  14. Optimum design of laminated composite under axial compressive load

    N G R Iyengar; Nilesh Vyas

    2011-02-01

    In the present study optimal design of composite laminates, with and without rectangular cut-out, is carried out for maximizing the buckling load. Optimization study is carried out for obtaining the maximum buckling load with design variables as ply thickness, cut-out size and orientation of cut-out with respect to laminate. Buckling load is evaluated using a ‘simple higher order shear deformation theory’ based on four unknown displacements $u,v,w_b$ and $w_s$. A C1 continuous shear flexible finite element based on HSDT model is developed using Hermite cubic polynomial. It is observed that for thick anti-symmetric laminates, the non-dimensional buckling load decreases with increase in aspect ratio and increase in fibre orientation angle. There is a decrease in the non-dimensional buckling load of symmetric laminate in the presence of cut-out.

  15. Preparation and characterization of electrically conductive composites of poly(vinyl alcohol–g–poly(acrylic acid hydrogels impregnated with polyaniline (PANI

    2008-01-01

    Full Text Available Novel electrically conducting composite materials consisting of poly(aniline (PANI nanoparticles dispersed in a poly(vinyl alcohol (PVA-g-poly(acrylic acid (PAA hydrogels were prepared within the polymer matrix by in situ polymerization of aniline. The conversion yield of aniline into PANI particles was determined gravimetrically while structural confirmation of the synthesized polymer was sought by Fourier Transform Infrared (FTIR, UV-visible analysis and X-ray diffraction (XRD technique. Morphology and dimension of PANI particles embedded into the colored optically semi-transparent hydrogels were evaluated by Scanning Electron Microscopy (SEM analysis. Electrical conductivity of composite hydrogels of different composition was determined by LCR meter while electroactive behavior of composite hydrogels swollen in electrolyte solution was investigated by Effective Bend Angle (EBA measurements.

  16. A pH-, salt- and solvent-responsive carboxymethylcellulose-g-poly(sodium acrylate/medical stone superabsorbent composite with enhanced swelling and responsive properties

    2011-05-01

    Full Text Available Free-radical graft copolymerization among sodium carboxymethylcellulose (CMC, partially neutralized acrylic acid (NaA, medical stone (MS and crosslinker N,N'-methylene-bis-acrylamide (MBA was performed to prepare new carboxymethylcellulose-g-poly(sodium acrylate/medical stone (CMC-g-PNaA/MS superabsorbent composites. Fourier transform infrared (FTIR spectra, thermogravimetry- differential scanning calorimetry (TG-DSC and field emission scanning electromicrsocopic (FESEM analysis confirmed that NaA had been grafted onto CMC backbone and MS participated in polymerization, and the thermal stability and surface morphologies were improved by the addition of MS. Energy dispersive spectrometer (EDS and elemental map (EM analyses revealed the better distribution of MS in the CMC-g-PNaA matrix. The incorporation of 20 wt% MS clearly enhanced the water absorption by 100% (from 317 to 634 g/g. The developed composites showed enhanced swelling rate and On-Off switching swelling characteristics in various pH solutions, saline solutions and hydrophilic organic solvents, which represented interesting and reversible pH-, saline- and hydrophilic organic solvent-responsive characteristics. In addition, the composite exhibited intriguing time-dependent kinetic swelling properties in various heavy metal solutions.

  17. Hybrid S2/Carbon Epoxy Composite Armours Under Blast Loads

    Dolce, F.; Meo, Michele; Wright, A.; French, M.; Bernabei, M.

    2012-06-01

    Civil and military structures, such as helicopters, aircrafts, naval ships, tanks or buildings are susceptible to blast loads as terroristic attacks increases, therefore there is the need to design blast resistant structures. During an explosion the peak pressure produced by shock wave is much greater than the static collapse pressure. Metallic structures usually undergo large plastic deformations absorbing blast energy before reaching equilibrium. Due to their high specific properties, fibre-reinforced polymers are being considered for energy absorption applications in blast resistant armours. A deep insight into the relationship between explosion loads, composite architecture and deformation/fracture behaviour will offer the possibility to design structures with significantly enhanced energy absorption and blast resistance performance. This study presents the results of a numerical investigation aimed at understanding the performance of a hybrid composite (glass/carbon fibre) plate subjected to blast loads using commercial LS-DYNA software. In particular, the paper deals with numerical 3D simulations of damages caused by air blast waves generated by C4 charges on two fully clamped rectangular plates made of steel and hybrid (S2/Carbon) composite, respectively. A Multi Materials Arbitrary Lagrangian Eulerian (MMALE) formulation was used to simulate the shock phenomenon. For the steel plates, the Johnson-Cook material model was employed. For the composite plates both in-plane and out-of-plane failure criteria were employed. In particular, a contact tiebreak formulation with a mixed mode failure criteria was employed to simulate delamination failure. As for the steel plates the results showed that excellent correlation with the experimental data for the two blast load conditions in terms of dynamic and residual deflection for two different C4 charges. For the composite plates the numerical results showed that, as expected, a wider delamination damage was observed

  18. Antibiotic-loaded acrylic bone cements: An in vitro study on the release mechanism and its efficacy

    Miola, Marta, E-mail: marta.miola@polito.it [Applied Science and Technology Department, Politecnico di Torino (Italy); Bistolfi, Alessandro [Department of Orthopaedics, Traumatology and HM, University of Turin (Italy); AO CTO, M Adelaide Hospital, Turin (Italy); Valsania, Maria Carmen; Bianco, Carlotta [Department of Orthopaedics, Traumatology and HM, University of Turin (Italy); Fucale, Giacomo [Chemical, Clinical and Microbiological Analyses Dept., CTO, Turin (Italy); Verné, Enrica [Applied Science and Technology Department, Politecnico di Torino (Italy)

    2013-07-01

    An in vitro study was carried out in order to investigate the antibiotic release mechanism and the antibacterial properties of commercially (Palacos® R + G and Palacos® LV + G) and manually (Palacos® R + GM and Palacos® LV + GM) blended gentamicin-loaded bone cements. Samples were characterized by means of scanning electron microscopy (SEM) and compression strength was evaluated. The antibiotic release was investigated by dipping sample in simulated body fluid (SBF) and periodically analyzing the solution by means of high pressure liquid chromatography (HPLC). Different antibacterial tests were performed to investigate the possible influence of blending technique on antibacterial properties. Only some differences were observed between gentamicin manually added and commercial ones, in the release curves, while the antibacterial effect and the mechanical properties seem to not feel the blending technique. Highlights: • The efficacy of commercially and manually mixed antibiotic-loaded cements is studied. • Exhaustive mechanical, drug release and antibacterial studies are carried out. • The blending technique does not affect the antibacterial and mechanical properties. • The blending process influences only the release curve, not the released drug amount.

  19. Antibiotic-loaded acrylic bone cements: An in vitro study on the release mechanism and its efficacy

    An in vitro study was carried out in order to investigate the antibiotic release mechanism and the antibacterial properties of commercially (Palacos® R + G and Palacos® LV + G) and manually (Palacos® R + GM and Palacos® LV + GM) blended gentamicin-loaded bone cements. Samples were characterized by means of scanning electron microscopy (SEM) and compression strength was evaluated. The antibiotic release was investigated by dipping sample in simulated body fluid (SBF) and periodically analyzing the solution by means of high pressure liquid chromatography (HPLC). Different antibacterial tests were performed to investigate the possible influence of blending technique on antibacterial properties. Only some differences were observed between gentamicin manually added and commercial ones, in the release curves, while the antibacterial effect and the mechanical properties seem to not feel the blending technique. Highlights: • The efficacy of commercially and manually mixed antibiotic-loaded cements is studied. • Exhaustive mechanical, drug release and antibacterial studies are carried out. • The blending technique does not affect the antibacterial and mechanical properties. • The blending process influences only the release curve, not the released drug amount

  20. Micromechanical design of hierarchical composites using global load sharing theory

    Rajan, V. P.; Curtin, W. A.

    2016-05-01

    Hierarchical composites, embodied by natural materials ranging from bone to bamboo, may offer combinations of material properties inaccessible to conventional composites. Using global load sharing (GLS) theory, a well-established micromechanics model for composites, we develop accurate numerical and analytical predictions for the strength and toughness of hierarchical composites with arbitrary fiber geometries, fiber strengths, interface properties, and number of hierarchical levels, N. The model demonstrates that two key material properties at each hierarchical level-a characteristic strength and a characteristic fiber length-control the scalings of composite properties. One crucial finding is that short- and long-fiber composites behave radically differently. Long-fiber composites are significantly stronger than short-fiber composites, by a factor of 2N or more; they are also significantly tougher because their fiber breaks are bridged by smaller-scale fibers that dissipate additional energy. Indeed, an "infinite" fiber length appears to be optimal in hierarchical composites. However, at the highest level of the composite, long fibers localize on planes of pre-existing damage, and thus short fibers must be employed instead to achieve notch sensitivity and damage tolerance. We conclude by providing simple guidelines for microstructural design of hierarchical composites, including the selection of N, the fiber lengths, the ratio of length scales at successive hierarchical levels, the fiber volume fractions, and the desired properties of the smallest-scale reinforcement. Our model enables superior hierarchical composites to be designed in a rational way, without resorting either to numerical simulation or trial-and-error-based experimentation.

  1. Areca Fiber Reinforced Epoxy Composites: Effect of Chemical Treatments on Impact Strength

    Dhanalakshmi, S.; Ramadevi, P.; Basavaraju, B.

    2015-01-01

    In this research work, impact strength of untreated, alkali treated, potassium permanganate treated, benzoyl chloride treated and acrylic acid treated areca fiber reinforced epoxy composites were studied under 40%, 50%, 60% and 70% fiber loadings. Impact strength increased with increase in fiber loading up to 60% and then showed a decline for all untreated and chemically treated areca fiber reinforced epoxy composites. The acrylic acid treated areca fiber reinforced epoxy composites with 60% ...

  2. Synthesis of poly(acrylic acid-maleic acid)SiO2/Al2O3 as novel composite material for cesium removal from acidic solutions

    A novel composite material of SiO2-Al2O3 based on poly(acrylic acid-maleic acid) was synthesized by irradiated with 60Co γ-rays at a dose of 25 KGy. The composite material was characterized using FTIR, TGA and BET surface area. Adsorption of 134Cs from HNO3 was studied as a function of contact time, temperature and concentration of Cs. Sorption behavior of 134Cs in different concentration of HCl, HNO3, acetic acid, ascorbic acid, citric acid, NaCl and NaNO3 solutions has been investigated. It can be concluded that the P(AA-MA)/SiO2/Al2O3 is promising adsorbent for Cs removal from acidic liquid radioactive waste. (author)

  3. pH-sensitive photocatalytic activities of TiO2/poly(vinyl alcohol)/poly(acrylic acid) composite hydrogels

    The pH-sensitive photocatalytic system was prepared by embedding TiO2 into poly(vinyl alcohol)/poly(acrylic acid) hydrogel. Two different type TiO2/hydrogel composites, such as matrix and nanofiber, were prepared to investigate the morphological effects on the photocatalytic activity. TiO2 was distributed uniformly in the composite hydrogel and kept the original anatase structure without any structural change. The photocatalytic activity of TiO2 was evaluated based on the efficiency of photobleaching of dye. The photobleaching of dye was improved greatly as the pH was changed into basic condition and the larger surface area of hydrogel was available for TiO2 by using nanofiber supports.

  4. Analysis of delamination growth in compressively loaded composite laminates

    Tratt, Matthew D.

    The present analytical and empirical study of composite structure delamination has attempted to predict the threshold stress for the initiation of delamination growth in compressively loaded composite laminates. The strain-energy release-rate distributions around circular delaminations are computed via MSC/NASTRAN analysis in conjunction with a virtual crack-opening technique. Static compression tests were conducted on specimens of graphite fiber-reinforced epoxy having circular delaminations of various sizes. Computed delamination growth threshold-stress prediction results were at substantial variance with the test data, but confirmed trends and gave qualitative insight into quasi-static delamination growth.

  5. Load sequence effects on the fatigue of unnotched composite materials

    Yang, J. N.; Jones, D. L.

    1981-01-01

    A more comprehensive version of an earlier fatigue and residual strength degradation model is proposed to predict the effect of load sequence on the statistical fatigue behavior of composite laminates. The model, which reduces to various fatigue models proposed in the literature by means of approximations, is verified by a survey of experiments on glass/epoxy laminates. It is shown that the correlation between the model and the test results under dual stress levels is reasonable, and that a simplified version of the model is verified by experiments on graphite/epoxy laminates in which the correlation between theoretical predictions and results under dual stress levels is satisfactory. The model is also shown capable of predicting the effect of proof loads on the fatigue behavior of composite materials.

  6. Dynamic Viscoelasticity of Polyester/Rubber Composites under Cyclic Loading

    Yuyan LIU; Zhenhui TIAN; Zhimin XIE; Xingwen DU

    2005-01-01

    This paper focuses on the influence of dynamic viscoelasticity and surface temperature on the fatigue mechanism and fatigue lifetime of polyester/rubber composites. Rubber composites show significant viscoelasticity during fatigue process. The variations of dynamic elastic modulus, mechanical loss angle, loss energy per cycle exhibit different trend in fatigue initial stage and final stage. Due to high viscoelasticity high heat generation occurs under cyclic loading, which leads to a high surface temperature. It is found that the variation of specimen surface temperaturedepends strongly on cycling frequency and stress amplitude. SEM (scanning electron microscopy) observation and static residual stiffness studies reveal that the surface temperature affects fracture morphology and fatigue lifetime of rubber composites strongly because of heat aging.

  7. Microcracking in composite laminates under thermal and mechanical loading. Thesis

    Maddocks, Jason R.

    1995-01-01

    Composites used in space structures are exposed to both extremes in temperature and applied mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. The goal of the present investigation is to develop a predictive methodology to quantify microcracking in general composite laminates under both thermal and mechanical loading. This objective is successfully met through a combination of analytical modeling and experimental investigation. In the analysis, the stress and displacement distributions in the vicinity of a crack are determined using a shear lag model. These are incorporated into an energy based cracking criterion to determine the favorability of crack formation. A progressive damage algorithm allows the inclusion of material softening effects and temperature-dependent material properties. The analysis is implemented by a computer code which gives predicted crack density and degraded laminate properties as functions of any thermomechanical load history. Extensive experimentation provides verification of the analysis. AS4/3501-6 graphite/epoxy laminates are manufactured with three different layups to investigate ply thickness and orientation effects. Thermal specimens are cooled to progressively lower temperatures down to -184 C. After conditioning the specimens to each temperature, cracks are counted on their edges using optical microscopy and in their interiors by sanding to incremental depths. Tensile coupons are loaded monotonically to progressively higher loads until failure. Cracks are counted on the coupon edges after each loading. A data fit to all available results provides input parameters for the analysis and shows them to be material properties, independent of geometry and loading. Correlation between experiment and analysis is generally very good under both thermal and mechanical loading, showing the methodology to be a powerful, unified tool. Delayed crack initiation observed in a few cases is attributed to a

  8. Optimization of Sandwich Composites Fuselages Under Flight Loads

    Yuan, Chongxin; Bergsma, Otto; Koussios, Sotiris; Zu, Lei; Beukers, Adriaan

    2012-02-01

    The sandwich composites fuselages appear to be a promising choice for the future aircrafts because of their structural efficiency and functional integration advantages. However, the design of sandwich composites is more complex than other structures because of many involved variables. In this paper, the fuselage is designed as a sandwich composites cylinder, and its structural optimization using the finite element method (FEM) is outlined to obtain the minimum weight. The constraints include structural stability and the composites failure criteria. In order to get a verification baseline for the FEM analysis, the stability of sandwich structures is studied and the optimal design is performed based on the analytical formulae. Then, the predicted buckling loads and the optimization results obtained from a FEM model are compared with that from the analytical formulas, and a good agreement is achieved. A detailed parametric optimal design for the sandwich composites cylinder is conducted. The optimization method used here includes two steps: the minimization of the layer thickness followed by tailoring of the fiber orientation. The factors comprise layer number, fiber orientation, core thickness, frame dimension and spacing. Results show that the two-step optimization is an effective method for the sandwich composites and the foam sandwich cylinder with core thickness of 5 mm and frame pitch of 0.5 m exhibits the minimum weight.

  9. Failure behavior of composite sandwich structures under local Loading

    Rizov, V. [University of Architecture, Civil Engineering and Geodesy, Department of Technical Mechanics, Sofia (Bulgaria)

    2009-03-15

    Usually when analyzing the mechanical response of foam-cored fiber-reinforced composite sandwich structures to localized static loading, the face sheets are treated as a linear-elastic material and no damage initiation and growth is considered. However, practice shows that at higher indentation magnitudes damage develops in the face sheet in the area of contact with the indentor, which could lead to local failure of the face laminate due to the loss of bending stiffness and strength. Therefore, the main objective of the present study is to develop a damage model for predicting the local failure in the composite face sheet and its influence on the load-displacement behavior of sandwich structures under local loading. For this purpose, the Hoffman failure criterion is incorporated into a finite element modeling procedure using the ABAQUS program system. Results deducted from the modeling procedure are compared with experimental data obtained in the case of static indentation tests performed on sandwich beam specimens using steel cylindrical indentors. It is shown that taking into account the damage in the face sheet leads to a substantial improvement in the performance of the model when simulating the mechanical behavior of the sandwich structures at higher indentation values. (orig.)

  10. Assessment of Composite Delamination Self-Healing Under Cyclic Loading

    O'Brien, T. Kevin

    2009-01-01

    Recently, the promise of self-healing materials for enhanced autonomous durability has been introduced using a micro-encapsulation technique where a polymer based healing agent is encapsulated in thin walled spheres and embedded into a base polymer along with a catalyst phase. For this study, composite skin-stiffener flange debonding specimens were manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin-walled spheres. Constant amplitude fatigue tests in three-point bending showed the effect of self-healing on the fatigue response of the skin-stiffener flange coupons. After the cycling that created debonding, fatigue tests were held at the mean load for 24 hours. For roughly half the specimens tested, when the cyclic loading was resumed a decrease in compliance (increase in stiffness) was observed, indicating that some healing had occurred. However, with continued cycling, the specimen compliance eventually increased to the original level before the hold, indicating that the damage had returned to its original state. As was noted in a prevoius study conducted with specimens tested under monotonically increasing loads to failure, healing achieved via the micro-encapsulation technique may be limited to the volume of healing agent available relative to the crack volume.

  11. Testing and simulation of composite laminates under impact loading

    Dang, Xinglai

    Owing to their high stiffness-to-weight and high strength-to-weight ratios, fiber-reinforced polymer-matrix composite laminates are excellent materials for high-performance structures. However, their properties in the thickness direction are very poor as they are weakly bonded by polymeric matrices through laminate interfaces. Accordingly, when a composite laminate is subjected to impact loading, high interlaminar stresses along with the low interlaminar strengths could easily result in interlaminar damage such as delamination. This thesis investigated the response of composite laminates under low-velocity impact and presented numerical techniques for impact simulation. To begin with, instrumented drop-weight impacts ranging from subperforation to perforation levels were introduced to composite laminates having various dimensions and thicknesses. Damaged composite laminates were then subjected to compression-after-impact tests for evaluations of residual properties. Experimental results revealed that perforation was an important damage milestone since impact parameters such as peak force, contact duration, maximum deflection and energy absorption, and residual properties such as compressive stiffness, strength and energy absorption all reached critical levels as perforation took place. It was also found that thickness played a more important role than in-plane dimensions in perforation process. In order to understand more about the relationship between laminate thickness and perforation resistance and to present an economical method to improve perforation resistance, thick laminated composite plates and their assembled counterparts were investigated and compared. An energy profile correlating the impact energy and absorbed energy at all energy levels for each type of composite plates investigated was established and found to be able to address the relationship between energy and damage. Experimental results concluded that increasing thickness was more efficient

  12. Study on acrylic acid bentonite of high amount/poly(sodium acrylate) superabsorbent composite Ⅰ :the preparation process and morphology%高含量丙烯酸膨润土/聚丙烯酸钠高吸水性复合材料的研究Ⅰ:制备工艺与形貌

    付丽华; 彭英知; 韦藤幼; 童张法

    2012-01-01

    Superabsorbent composite of high amount of acrylic acid bentonite/poly(sodium acrylic) was synthesized through solution polymerization with acrylic acid bentonite(ABT) and sodium acrylic and acrylic acid. The morphology of the composite was observed by scanning electron microscope(SEM). The results show that a-crylic acid bentonite is evenly and disorder dispersed in the composite with the sheets of 20-30 nm thickness. The preparation process are optimized. The results are as follows. The amount of ABT, crosslinker and initiator are 30wt% , 0. 3wt% , 1. lwt% of the monomer mass respectively. The total water in the system is 340 % of the monomer mass, the neutralization degree is 64 %). The absorbency of the composite is 1103 g/g in deionized water in the conditions. At the same time, the water retention property of the superabsorbent composite(PAA) is better compared to that of PAA.%通过特殊工艺将丙烯酸膨润土(简称ABT)和丙烯酸钠单体采用溶液聚合法制备出高含量丙烯酸膨润土/聚丙烯酸钠高吸水性复合材料(简称HABT/PAA).SEM考察材料的形貌得知,ABT以20~30nm的尺寸较均匀、无序地分散在聚合物基体中,且与聚合物有很好的相容性.对合成工艺进行了优化得到较优的工艺:ABT用量为单体质量的30%(质量分数),交联剂用量为单体质量的0.3%(质量分数),引发剂用量为单体质量的1.1%(质量分数),体系总水量为单体质量的340%(质量分数),中和度为64%,在此条件下,材料吸附去离子水的能力为1103g/g.同时,HABT/PAA的保水性能较聚丙烯酸钠(PAA)好.

  13. Areca Fiber Reinforced Epoxy Composites: Effect of Chemical Treatments on Impact Strength

    S. Dhanalakshmi

    2015-06-01

    Full Text Available In this research work, impact strength of untreated, alkali treated, potassium permanganate treated, benzoyl chloride treated and acrylic acid treated areca fiber reinforced epoxy composites were studied under 40%, 50%, 60% and 70% fiber loadings. Impact strength increased with increase in fiber loading up to 60% and then showed a decline for all untreated and chemically treated areca fiber reinforced epoxy composites. The acrylic acid treated areca fiber reinforced epoxy composites with 60% fiber loading showed highest impact strength of 28.28 J/mm2 amongst all untreated and chemically treated areca/epoxy composites with same 60% fiber loading.

  14. Synthesis and Characterization of Chemically Cross-Linked Acrylic Acid/Gelatin Hydrogels: Effect of pH and Composition on Swelling and Drug Release

    Syed Majid Hanif Bukhari

    2015-01-01

    Full Text Available This present work was aimed at synthesizing pH-sensitive cross-linked AA/Gelatin hydrogels by free radical polymerization. Ammonium persulfate and ethylene glycol dimethacrylate (EGDMA were used as initiator and as cross-linking agent, respectively. Different feed ratios of acrylic acid, gelatin, and EGDMA were used to investigate the effect of monomer, polymer, and degree of cross-linking on swelling and release pattern of the model drug. The swelling behavior of the hydrogel samples was studied in 0.05 M USP phosphate buffer solutions of various pH values pH 1.2, pH 5.5, pH 6.5, and pH 7.5. The prepared samples were evaluated for porosity and sol-gel fraction analysis. Pheniramine maleate used for allergy treatment was loaded as model drug in selected samples. The release study of the drug was investigated in 0.05 M USP phosphate buffer of varying pH values (1.2, 5.5, and 7.5 for 12 hrs. The release data was fitted to various kinetic models to study the release mechanism. Hydrogels were characterized by Fourier transformed infrared (FTIR spectroscopy which confirmed formation of structure. Surface morphology of unloaded and loaded samples was studied by surface electron microscopy (SEM, which confirmed the distribution of model drug in the gel network.

  15. Modeling of damage evaluation in thin composite plate loaded by pressure loading

    Dudinský M.

    2012-12-01

    Full Text Available This article presents the results of numerical analysis of elastic damage of thin laminated long fiber-reinforced composite plate consisting of unidirectional layers which is loaded by uniformly distributed pressure. The analysis has been performed by means of the finite element method (FEM. The numerical implementation uses layered plate finite elements based on the Kirchhoff plate theory. System of nonlinear equations has been solved by means of the Newton- Raphson procedure. Evolution of damage has been solved using the return-mapping algorithm based on the continuum damage mechanics (CDM. The analysis was performed using own program created in MATLAB. Problem of laminated fiber-reinforced composite plate fixed on edges for two different materials and three different laminate stacking sequences (LSS was simulated. Evolution of stresses vs. strains and also evolution of damage variables in critical points of the structure are shown.

  16. Synthesis of acrylic prepolymer

    An acrylic prepolymer was synthesized from glycidyl methacrylate (GMA), butyl methacrylate (BMA), methyl methacrylate (MMA) and acrylic acid (AA). Butyl acetate (BAc), benzoyl peroxide (BzO), 4-methoxyphenol (MPh) and triethylamine (TEA) were used as solvent, initiator, inhibitor and catalyst respectively. Observations of the synthesis leading to the formation of acrylic prepolymer are described. (author)

  17. Innovative Manufacturing of Carbon Nanotube-Loaded Fibrillar Polymer Composites

    Lin, R. J. T.; Bhattacharyya, D.; Fakirov, S.

    The concept of microfibrillar composite (MFC) has been used to create a new type of polymer composites, in which the reinforcing microfibrils are loaded with carbon nanotubes (CNT). Polyamide 66 (PA66) has been melt blended with polypropylene in a twin screw extruder with and without CNT, and thereafter cold drawn to create a fibrillar state as well as to align the CNT in the PA66 microfibrils. The drawn bristles were compression moulded at 180°C to prepare MFC plates. The scanning electron microscope (SEM) observations indicate near perfect distribution of CNT in the reinforcing PA66 microfibrils. Although the fibrillated PA66 is able to improve the tensile stiffness and strength as expected from the MFC structure, the incorporation of CNT does not exhibit any further enhancing effect. It rather adversely affects the mechanical properties due to poor interface adhesion between the matrix and the reinforcing microfibrils with the presence of CNT, as demonstrated by SEM. However, the resulting highly aligned CNT within the MFC are expected to affect the physical and functional properties of these composites.

  18. Active shape control of composite structures under thermal loading

    Binette, P.; Dano, M.-L.; Gendron, G.

    2009-02-01

    Maintaining the shape of high-precision structures such as space antennas and optical mirrors is still a challenging issue for designers. These structures are subjected to varying temperature conditions which often introduce thermal distortions. The development of smart materials offers great potential to correct the shape and to minimize the surface error. In this study, shape control of a composite structure under thermal loading using piezocomposites is investigated. The composite structure is made of a foam core and two carbon-epoxy face sheets. Macro-fiber composite (MFC™) patches are bonded on one side of the structure. The structure is subjected to a through-the-thickness temperature gradient which induces thermal distortion, essentially in the form of bending. The objective is to apply electric potential to the MFC™ actuators such that the deflection can be minimized. Finite-element analyses are conducted using the commercial software ABAQUS. Experiments are performed to study thermally induced distortion, piezoelectric actuation, and compensation of thermal distortion using MFC™ actuators. Numerical and experimental results are compared. A control loop based on strain measurements is used to actively control the structure. The results show that MFC™ actuators can compensate thermal distortion at all times, and that this is an efficient methodology.

  19. Active shape control of composite structures under thermal loading

    Maintaining the shape of high-precision structures such as space antennas and optical mirrors is still a challenging issue for designers. These structures are subjected to varying temperature conditions which often introduce thermal distortions. The development of smart materials offers great potential to correct the shape and to minimize the surface error. In this study, shape control of a composite structure under thermal loading using piezocomposites is investigated. The composite structure is made of a foam core and two carbon–epoxy face sheets. Macro-fiber composite (MFC(TM)) patches are bonded on one side of the structure. The structure is subjected to a through-the-thickness temperature gradient which induces thermal distortion, essentially in the form of bending. The objective is to apply electric potential to the MFC(TM) actuators such that the deflection can be minimized. Finite-element analyses are conducted using the commercial software ABAQUS. Experiments are performed to study thermally induced distortion, piezoelectric actuation, and compensation of thermal distortion using MFC(TM) actuators. Numerical and experimental results are compared. A control loop based on strain measurements is used to actively control the structure. The results show that MFC(TM) actuators can compensate thermal distortion at all times, and that this is an efficient methodology

  20. A preliminary study of the composition of commercial oil, acrylic and vinyl paints and their behaviour after accelerated ageing conditions

    Francesca Caterina Izzo

    2014-12-01

    Full Text Available This study is part of a research project dealing with the establishment of monitoring and damage prevention plans for contemporary artworks. For this purpose, some commercial paints, among the most currently used by young artists, were selected: Winton oil paint (Winsor & Newton, UK, Heavy Body acrylic paint (Liquitex, USA and Flashe vinyl paint (Lefranc & Bourgeois, France. The paints were subjected to different treatments of accelerated ageing, the results indicating different behaviour in relation both to the type of binders and pigments present in the different formulations. In particular, it was observed that ageing produced by ozone plays an important role in the stability of the oil paints, above all in those containing organic azo pigments. Thermal ageing, as expected, influences the stability of all the commercial paints examined, with the formation of alteration products and visible changes in the paint films. Ageing produced by moisture clearly affects the synthetic polymer-based paints, particularly evident in the changes in mass. In all cases, the accelerated ageing treatments produced chromatic variations, more evidently for the oil paints containing organic pigment.

  1. Thermal and topographical characterization of polyester- and styrene/acrylate-based composite powders by scanning probe microscopy

    Backfolk, Kaj [Stora Enso Oyj, Imatra Research Centre, FI-55 800 Imatra (Finland)], E-mail: Kaj.Backfolk@storaenso.com; Sirvioe, Petri [Stora Enso Oyj, Imatra Research Centre, FI-55 800 Imatra (Finland); Department of Physical Chemistry, Abo Akademi University, Porthaninkatu 3-5, FI-20500 Turku (Finland); Ihalainen, Petri [Department of Physical Chemistry, Abo Akademi University, Porthaninkatu 3-5, FI-20500 Turku (Finland); Peltonen, Jouko [Laboratory of Paper Coating and Converting, Abo Akademi University, Porthaninkatu 3-5, FI-20500 Turku (Finland)

    2008-04-10

    The thermal properties of two conventional polyester-based toners and a chemically prepared styrene/acrylate toner with different thermal histories were studied by scanning probe microscopy (SPM) and differential scanning calorimetry (DSC). The thermal transition temperatures detected by SPM agreed with the results of the DSC measurements. The validity of SPM for detecting thermal transitions was further confirmed by studying two amorphous reference polymers with different glass transition points (T{sub g}) and three crystalline reference polymers with different melting points (T{sub m}). When the toner sample was heated by the SPM probe above the glass transition temperature of the toner powder (T{sub probe} > T{sub g}), changes occurred in the surface topography and roughness causing different levels of local sintering of the particles. A set of roughness parameters calculated from the SPM image data were used to quantify the most essential features of toner surfaces. Environmental scanning electron microscopy (ESEM) was used to study the penetration depth of heat dissipated by the SPM probe. The probe-annealing was compared with oven-annealing in order to establish the effect of thermal history on the thermal properties of the materials.

  2. Thermal and topographical characterization of polyester- and styrene/acrylate-based composite powders by scanning probe microscopy

    The thermal properties of two conventional polyester-based toners and a chemically prepared styrene/acrylate toner with different thermal histories were studied by scanning probe microscopy (SPM) and differential scanning calorimetry (DSC). The thermal transition temperatures detected by SPM agreed with the results of the DSC measurements. The validity of SPM for detecting thermal transitions was further confirmed by studying two amorphous reference polymers with different glass transition points (Tg) and three crystalline reference polymers with different melting points (Tm). When the toner sample was heated by the SPM probe above the glass transition temperature of the toner powder (Tprobe > Tg), changes occurred in the surface topography and roughness causing different levels of local sintering of the particles. A set of roughness parameters calculated from the SPM image data were used to quantify the most essential features of toner surfaces. Environmental scanning electron microscopy (ESEM) was used to study the penetration depth of heat dissipated by the SPM probe. The probe-annealing was compared with oven-annealing in order to establish the effect of thermal history on the thermal properties of the materials

  3. Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

    Hamid Kermanshah

    2016-01-01

    Conclusion: Silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except Aelite. In addition, cyclic loading did not affect the marginal microleakage of evaluated composite restorations .

  4. Fracture control method for composite tanks with load sharing liners

    Bixler, W. D.

    1975-01-01

    The experimental program was based on the premise that the plastic sizing cycle, which each pressure vessel is subjected to prior to operation, acts as an effective proof test of the liner, screening out all flaws or cracks larger than a critical size. In doing so, flaw growth potential is available for cyclic operation at pressures less than the sizing pressure. Static fracture and cyclic life tests, involving laboratory type specimens and filament overwrapped tanks, were conducted on three liner materials: (1) 2219-T62 aluminum, (2) Inconel X750 STA, and (3) cryoformed 301 stainless steel. Variables included material condition, thickness, flaw size, flaw shape, temperature, sizing stress level, operating stress level and minimum-to-maximum operating stress ratio. From the empirical data base obtained, a procedure was established by which the service life of composite tanks with load sharing liners could be guaranteed with a high degree of confidence.

  5. Energy absorption capabilities of composite sandwich panels under blast loads

    Sankar Ray, Tirtha

    As blast threats on military and civilian structures continue to be a significant concern, there remains a need for improved design strategies to increase blast resistance capabilities. The approach to blast resistance proposed here is focused on dissipating the high levels of pressure induced during a blast through maximizing the potential for energy absorption of composite sandwich panels, which are a competitive structural member type due to the inherent energy absorption capabilities of fiber reinforced polymer (FRP) composites. Furthermore, the middle core in the sandwich panels can be designed as a sacrificial layer allowing for a significant amount of deformation or progressive failure to maximize the potential for energy absorption. The research here is aimed at the optimization of composite sandwich panels for blast mitigation via energy absorption mechanisms. The energy absorption mechanisms considered include absorbed strain energy due to inelastic deformation as well as energy dissipation through progressive failure of the core of the sandwich panels. The methods employed in the research consist of a combination of experimentally-validated finite element analysis (FEA) and the derivation and use of a simplified analytical model. The key components of the scope of work then includes: establishment of quantified energy absorption criteria, validation of the selected FE modeling techniques, development of the simplified analytical model, investigation of influential core architectures and geometric parameters, and investigation of influential material properties. For the parameters that are identified as being most-influential, recommended values for these parameters are suggested in conceptual terms that are conducive to designing composite sandwich panels for various blast threats. Based on reviewing the energy response characteristic of the panel under blast loading, a non-dimensional parameter AET/ ET (absorbed energy, AET, normalized by total energy

  6. Composite Vessels for Containment of Extreme Blast Loadings

    Pastrnak, J; Henning, C; Grundler, W; Switzer, V; Hollaway, R; Morrison, J; Hagler, L; Kokko, E; Deteresa, S; Hathcoat, B; Dalder, E

    2004-07-15

    A worldwide trend for explosives testing has been to replace open-air detonations with containment vessels, especially when any hazardous materials are involved. As part of the National Nuclear Security Administration's (NNSA) effort to ensure the safety and reliability of the nation's nuclear stockpile, researchers at Lawrence Livermore National Laboratory have been developing a high performance filament wound composite firing vessel that is nearly radiographically transparent. It was intended to contain a limited number of detonations of metal cased explosive assemblies in radiographic facilities such as the Advanced Hydrodynamic Facility (AHF) being studied by Los Alamos National Laboratory. A 2-meter diameter pressure vessel was designed to contain up to 35 kg (80 lb) of TNT equivalent explosive without leakage. Over the past 5 years a total of three half-scale (1 meter diameter) vessels have been constructed, and two of them were tested to 150% load with 8.2 kg (18-pound) spheres of C4 explosive. The low density and high specific strength advantages used in this composite vessel design may have other additional applications such as transporting sensitive explosives that could otherwise be moved only in very small quantities. Also, it could be used for highly portable, explosive containment systems for law enforcement.

  7. Effect of in vivo loading on bone composition varies with animal age.

    Aido, Marta; Kerschnitzki, Michael; Hoerth, Rebecca; Checa, Sara; Spevak, Lyudmila; Boskey, Adele L; Fratzl, Peter; Duda, Georg N; Wagermaier, Wolfgang; Willie, Bettina M

    2015-03-01

    Loading can increase bone mass and size and this response is reduced with aging. It is unclear, however how loading affects bone mineral and matrix properties. Fourier transform infrared imaging and high resolution synchrotron scanning small angle X-ray scattering were used to study how bone's microscale and nanoscale compositional properties were altered in the tibial midshaft of young, adult, and elderly female C57Bl/6J mice after two weeks of controlled in vivo compressive loading in comparison to physiological loading. The effect of controlled loading on bone composition varied with animal age, since it predominantly influenced the bone composition of elderly mice. Interestingly, controlled loading led to enhanced collagen maturity in elderly mice. In addition, although the rate of bone formation was increased by controlled loading based on histomorphometry, the newly formed tissue had similar material quality to the new bone tissue formed during physiological loading. Similar to previous studies, our data showed that bone composition was animal age- and tissue age-dependent during physiological loading. The findings that the new tissue formed in response to controlled loading and physiological loading had similar bone composition and that controlled loading enhanced bone composition in elderly mice further support the use of physical activity as a noninvasive treatment to enhance bone quality as well as maintain bone mass in individuals suffering from age-related bone loss. PMID:25639943

  8. Synthesis and characterization of chitosan-graft-poly(acrylic acid)/rice husk ash hydrogels composites; Sintese e caracterizacao de hidrogeis compositos de cinza da casca de arroz e quitosana enxertada com poli(acido acrilico)

    Rodrigues, Francisco H.A. [Universidade Estadual Vale do Acarau - UVA, Sobral, CE (Brazil); Lopes, Gabriel V.; Pereira, Antonio G.B.; Fajardo, Andre R.; Muniz, Edvani C. [Universidade Estadual de Maringa - UEM, PR (Brazil)

    2011-07-01

    According to environmental concerns, super absorbent hydrogel composites were synthesized based on rice husk ash (RHA), an industrial waste, and Chitosan-graft-poly(acrylic acid). The WAXS and FTIR data confirmed the syntheses of hydrogel composites. The effect of crystalline or amorphous RHA on water uptake was investigated. It was found that the RHA in crystalline form induces higher water capacity (W{sub eq}) of composites hydrogels due to the fact that the intra-interactions among silanol groups on RHA make available new sites in the polymer matrix, which could interact to water. (author)

  9. Response of marine composites subjected to near field blast loading

    LiVolsi, Frank

    Experimental studies were performed to understand the explosive response of composite panels when exposed to near-field explosive loading in different environments. The panel construction under consideration was an E-glass fiber-reinforced composite laminate infused with vinyl ester resin (Derakane 8084). The panel was layered bi-axially with plain-woven fiber orientations at 0° and 90°. Panel dimensions were approximately 203 mm x 203 mm x 1 mm (8 in x 8 in x 0.04 in). Experiments were carried out with the panel fully clamped in a holding fixture, which was in turn fastened inside a water tank. The fixture was fastened in such a way as to allow for explosive loading experiments in the following environments: water submersion with water backing, water submersion with air backing, and air immersion with air backing. Experiments were performed in room temperature conditions, and additional experiments in the submerged environments were also performed at high and low water temperatures of 40°C and 0°C, respectively. A stereo Digital Image Correlation (DIC) system was employed to capture the full-field dynamic behavior of the panel during the explosive event. Results indicated that the immersion environment contributes significantly to the blast response of the material and to the specimens' appreciable damage characteristics. The water submersion with air backing environment was found to encourage the greatest panel center point deflection and the most significant damage mechanisms around the boundary. The air immersion with air backing environment was found to encourage less center point deflection and exhibited significant impact damage from the explosive capsule. The water submersion with water backing environment encouraged the least panel deflection and minimal interlaminate damage around the panel boundary and center. Water temperature was found to influence the panel center point deflection, but not damage mechanisms. Maximum positive center point

  10. Performance of patch repaired composite panels under fatigue loads

    This paper evaluates the performance of bonded patch-scarf repairs of full scale laminated composite panels under cyclic load conditions. Nondestructive testing to characterize the quality of repairs and destructive testing to evaluate the performance of repaired panels were used in this study. Carbon/Epoxy prepreg material used was used to lay up six-ply (12 in. x 27 in. /305x686mm) (-60/60/0) s quasi-isotropic laminates. 7-ply scarf repair with a gradient of 0.5 inch (12.7mm) per layer was used to perform the repair of a damaged zone. The patch consisted of 7.5 inches (190mm) diameter adhesive film, 1 inch (25.4mm) diameter filler ply at 90fiber orientation, and six plies (2-7 inches (51-178mm) diameter) to match the lay-up of the parent material. The study was extended to include defective repairs. The defect was engineered by inserting a 1 inch (25.4 mm) circular Teflon flaw between the fifth and sixth layers of the patch. A total of 28 panels were prepared and divided into five categories: (1) three pristine panels (undamaged parental materials); (2) three damaged panels (1-inch-centered-hole); (3) two repaired panels with wrong fiber orientation; (4) nine good repaired panels, and (5) eleven defective repair panels (1 inch flaw). A nondestructive evaluation to check the conditions of the repairs was performed on most of the tested panels that include the pulse-echo C-scan and pseudo through transmission air coupled and water coupled C-scan. Based on the results of the experimental evaluation of this study, good repair restored 95% of the tensile strength while defective repair restored 90% of the tensile strength of the pristine panels. Under fatigue loading, panels repaired with a 1 inch delamination flaw within the patch layers showed a major reduction in fatigue life compared to the good repair panels under similar loading conditions. (author)

  11. Development of highly-filled, bioactive acrylic-based composite bone cements for orthopedic and craniofacial surgery: Tuning of material properties after incorporation of calcium phosphate and antimicrobial fillers

    Rodriguez, Lucas Carlos

    Bone cements are used in a variety of healthcare specialties ranging from orthopedics to dentistry to craniofacial surgery to spinal disc reconstruction. These materials need characteristics which mimic their surrounding tissues. Currently available materials have struggled to maintain these necessary characteristics. Poly (methyl methacrylate) is a very high strength bio-inert polymer which has been utilized in healthcare since the 1940's. Calcium phosphate cements are well established as being bone mimicking, but cannot sustain the compressive loads in a weight bearing application. This study sought to solve the problem of currently available bone cements by filling calcium phosphates and antimicrobials into an acrylic polymer matrix. The intended outcome was a material capable of retaining high mechanical stability from the acrylic polymer phase, while becoming sufficiently bone mimicking and antimicrobial. This thesis work presented, characterizes the material properties of the developed materials and eventually isolates a material of interest for future studies.

  12. Synthesis of berberine loaded polymeric nanoparticles by central composite design

    Mehra, Meenakshi; Sheorain, Jyoti; Kumari, Santosh

    2016-04-01

    Berberine is an isoquinoline alkaloid which is extracted from bark and roots of Berberis vulgaris plant. It has been used in ayurvedic medicine as it possess antimicrobial, antidiabetic, anticancer, antioxidant properties etc. But poor solubility of berberine leads to poor stability and bioavailability in medical formulations decreasing its efficacy. Hence nanoformulations of berberine can help in removing the limiting factors of alkaloid enhancing its utilization in pharmaceutical industry. Sodium alginate polymer was used to encapsulate berberine within nanoparticles by emulsion solvent evaporation method using tween 80 as a surfactant. Two factors and three level in central composite design was used to study the formulation. The optimized formulation (1% v/v of Tween 80 and 0.01% w/v of sodium alginate) of polymeric nanoparticles was taken for further evaluations. The size of synthesized nanoparticles was found to be 71.18 nm by particle size analysis (PSA). The berberine loaded polymeric nanoparticles showed better antibacterial activity compared to aqueous solution of berberine by well diffusion assay.

  13. LDEXPT, an intelligent database system for the Composite Load Spectra project

    Ho, H.; Newell, J. F.; Hopkins, D.; Chamis, C. C.

    1990-01-01

    The Composite Load Spectra project develops probabilistic models to simulate the probabilistic loads for selected components of a generic space propulsion system. Tremendous information such as engine load variables and their distributions is needed by the simulation program. An intelligent data base system was constructed and integrated with the probabilistic load simulation program to manage and maintain the knowledge base of the Composite Load Spectra project. The intelligent data base system takes care of the data retrieval and storage functions and has expert knowledge on engine load models and associated engine variables. The integration of the intelligent data base into the load simulation program achieves a smooth coupling between the numeric processing (load simulation calculation) and the symbolic processing (intelligent load information management).

  14. Polymer optical waveguide composed of europium-aluminum-acrylate composite core for compact optical amplifier and laser

    Mitani, Marina; Yamashita, Kenichi; Fukui, Toshimi; Ishigure, Takaaki

    2015-02-01

    We successfully fabricate polymer waveguides with Europium-Aluminum (Eu-Al) polymer composite core using the Mosquito method that utilizes a microdispenser for realizing a compact waveguide optical amplifiers and lasers. Rareearth (RE) ions are widely used as the gain medium for fiber lasers and optical fiber amplifiers. However, high concentration doping of rare-earth-ion leads to the concentration quenching resulting in observing less gain in optical amplification. For addressing the concentration quenching problem, a rare-earth metal (RE-M) polymer composite has been proposed by KRI, Inc. to be a waveguide core material. Actually, 10-wt% RE doping into organic polymer materials was already achieved. Hence, realization of compact and high-efficiency waveguide amplifiers and lasers have been anticipated using the RE-M polymer composite. In this paper, a microdispenser is adopted to fabricate a Eu-doped polymer waveguide. Then, it is experimentally confirmed that the low-loss waveguides are fabricated with a high reproducibility. Optical gain is estimated by measuring the amplified spontaneous emission using the variable stripe length method. The fabricated waveguide exhibits an optical gain as high as 7.1 dB/cm at 616-nm wavelength.

  15. 新型喷涂用双组分聚脲/丙烯酸聚氨酯复合涂料%Novel Tow-component Polyurea/Acrylic Polyurethane Composite Coating for Spray

    仇伟; 刘见祥; 潘鲁; 张波; 刘蔚凯; 曾舒

    2013-01-01

    采用羟基丙烯酸树脂与聚天门冬氨酸酯制备喷涂用双组分聚脲/丙烯酸聚氨酯涂料,考察了涂料的基本性能,研究了两种树脂的配比、流平剂用量等对涂料性能的影响.结果表明,当羟基丙烯酸树脂与聚天门冬氨酸酯的质量比为35∶45,流平剂用量为0.3%时,涂料具有优良的综合性能和耐老化性能.%The tow-component polyurea/ acrylic polyurethane composite coating for spray was prepared by using hydrox-yl acrylic resins and polyaspartic. The basic properties of the coatings were investigated, and the influences of the ratio of two resins and flow agent on the properties of coating were studied. The results show that when using hydroxy acrylic resin and polyaspartic at 35 : 45, flow agent 0. 3% , the composite coating provides excellent comprehensive performance and anti-aging properties.

  16. Silicone/Acrylate Copolymers

    Dennis, W. E.

    1982-01-01

    Two-step process forms silicone/acrylate copolymers. Resulting acrylate functional fluid is reacted with other ingredients to produce copolymer. Films of polymer were formed by simply pouring or spraying mixture and allowing solvent to evaporate. Films showed good weatherability. Durable, clear polymer films protect photovoltaic cells.

  17. Exploring the piezoelectric performance of PZT particulate-epoxy composites loaded in shear

    Van Loock, F.; Deutz, D. B.; van der Zwaag, S.; Groen, W. A.

    2016-08-01

    The active and passive piezoelectric response of lead zirconium titanate (PZT)-epoxy particulate composites loaded in shear is studied using analytical models, a finite element model and by experiments. The response is compared to that of the same composites when loaded in simple tension. Analogously to bulk PZT, particulate PZT-polymer composites loaded in shear show higher piezoelectric charge coefficient (d 15) and energy density figure of merit (FOM15) values compared to simple tension (d 33) and (FOM33). This outcome demonstrates the as-yet barely explored potential of piezoelectric particulate composites for optimal strain energy harvesting when activated in shear.

  18. Performance of Pre-Stressed Sandwich Composites Subjected to Shock Wave Loading

    Shukla A.

    2010-06-01

    Full Text Available The present paper experimentally studies the dynamic behaviour of prestressed sandwich composites under blast loading. The in-plane static compression loadings are implemented on the sandwich composites before they are subjected to the transverse shock wave loading. Three different pre-stress levels are chosen. 3-D realtime deformation data are captured by two high-speed photography systems: a backview Digital Image Correlation (DIC system and a side-view camera system. The results show that pre-stresses can induce local buckling in the front face-sheet of sandwich composites, consequently reduce the blast resistance of sandwich composites.

  19. 聚丙烯酸-腐植酸钠复合高吸水树脂的合成研究∗%Study on the Synthesis of Poly Acrylic Acid-sodium Humate Composite Super Absorbent Polymer

    李东芳; 杜明华

    2015-01-01

    该研究采用不除去丙烯酸中阻聚剂及不通氮气的工艺,以丙烯酸、腐植酸钠为原料,通过水溶液聚合法制备了聚丙烯酸-腐植酸钠复合高吸水树脂。研究结果表明:该复合高吸水树脂在丙烯酸的中和度为60%,腐植酸钠用量为1.0g,引发剂过硫酸钾用量为55mg,交联剂N,N′-亚甲基双丙烯酰胺用量为20mg时,吸蒸馏水量最大,为1200 g/g。%The poly acrylic acid-sodium humate composite super absorbent polymer was synthesized by aqueous solution polymerization through the technology of no nitrogen and not removing polymerization inhibitor in acrylic acid. In the synthesis process, acrylic acid and sodium humate were as monomer. The study results showed that when the neutralization degree of acrylic acid was 60%,the dosage of sodium humate was 1. 0g,the dosage of initia-tor( potassium persulfate) was 55mg, and the dosage of crosslinking agent ( N, N′-methylenebisacrylamide) was 20mg,the highest distilled water-absorbing capacity of the composite super absorbent polymer was 1200g/g.

  20. Effect of a silane coupling agent on the optical and the mechanical characteristics of nano diamond / acrylic resin composites

    Nano diamond (ND) is a good candidate for a filler material to fabricate transparent films. This study explores a characterization of the optical and the mechanical properties of ND dispersed polymer films. An attrition milling method was adapted to break ND aggregates, and a silane coupling agent (3-methacryloxy propyl trimethoxysilane) was used to modify the ND surfaces and stabilize the dispersion. Dipentaerylthritol hexaacrylate and pentaerythritol tetraacrylate were used in the polymer matrix, and up to 3 wt.% of ND was added to improve the mechanical properties. Fabricated composites were analyzed and tested using UV-visible spectroscopy for the optical properties and a Micro-Vickers hardness tester and ball-on-disktype friction tester for the mechanical properties. Results show that the transmittance of the ND-added composite increased with decreasing aggregate size. Through the addition of small amounts of NDs, the mechanical properties were greatly improved, the material became 3.5 times as hard, and the wear rate were greatly decreased. Possible mechanisms responsible for the enhancement of the mechanical and the optical properties are discussed.

  1. Effect of a silane coupling agent on the optical and the mechanical characteristics of nano diamond / acrylic resin composites

    Jeong, Min-Gun; Chun, Yoon-Soo; Lim, Dae-Soon [Korea University, Seoul (Korea, Republic of); Kim, Jung Youl [LG Electronics Inc., Seoul (Korea, Republic of)

    2014-10-15

    Nano diamond (ND) is a good candidate for a filler material to fabricate transparent films. This study explores a characterization of the optical and the mechanical properties of ND dispersed polymer films. An attrition milling method was adapted to break ND aggregates, and a silane coupling agent (3-methacryloxy propyl trimethoxysilane) was used to modify the ND surfaces and stabilize the dispersion. Dipentaerylthritol hexaacrylate and pentaerythritol tetraacrylate were used in the polymer matrix, and up to 3 wt.% of ND was added to improve the mechanical properties. Fabricated composites were analyzed and tested using UV-visible spectroscopy for the optical properties and a Micro-Vickers hardness tester and ball-on-disktype friction tester for the mechanical properties. Results show that the transmittance of the ND-added composite increased with decreasing aggregate size. Through the addition of small amounts of NDs, the mechanical properties were greatly improved, the material became 3.5 times as hard, and the wear rate were greatly decreased. Possible mechanisms responsible for the enhancement of the mechanical and the optical properties are discussed.

  2. Effect of a silane coupling agent on the optical and the mechanical characteristics of nanodiamond/acrylic resin composites

    Jeong, Min-Gun; Chun, Yoon-Soo; Lim, Dae-Soon; Kim, Jung Youl

    2014-10-01

    Nanodiamond (ND) is a good candidate for a filler material to fabricate transparent films. This study explores a characterization of the optical and the mechanical properties of ND dispersed polymer films. An attrition milling method was adapted to break ND aggregates, and a silane coupling agent (3-methacryloxypropyltrimethoxysilane) was used to modify the ND surfaces and stabilize the dispersion. Dipentaerylthritol hexaacrylate and pentaerythritol tetraacrylate were used in the polymer matrix, and up to 3 wt.% of ND was added to improve the mechanical properties. Fabricated composites were analyzed and tested using UV-visible spectroscopy for the optical properties and a Micro-Vickers hardness tester and ball-on-disktype friction tester for the mechanical properties. Results show that the transmittance of the ND-added composite increased with decreasing aggregate size. Through the addition of small amounts of NDs, the mechanical properties were greatly improved, the material became 3.5 times as hard, and the wear rate were greatly decreased. Possible mechanisms responsible for the enhancement of the mechanical and the optical properties are discussed.

  3. Injectable, high modulus, and fatigue resistant composite scaffold for load-bearing soft tissue regeneration.

    Hayami, James W S; Waldman, Stephen D; Amsden, Brian G

    2013-12-01

    High modulus, two-phase, bicontinuous scaffolds were prepared by photocross-linking an aqueous suspension of chondrocytes and N-methacrylate glycol chitosan with a hydrolyzable, hydrophobic, acrylated star-copolymer. Two acrylated star-copolymers were examined: poly(ε-caprolactone-co-d,l-lactide) (5446DLLACL) and poly(ε-caprolactone-co-trimethylene carbonate) (7030TMCCL). The scaffolds were assessed for injectability, two-phase interconnectivity, fatigue resistance, and long-term static culture behavior. The 7030TMCCL scaffolds demonstrated decreased moduli of 17% after 1 × 10(6) cycles at 30% strain and 5% after 56 days in culture, compared to the 5446DLLACL scaffolds, which exhibited decreases of 58 and 68%, respectively. The 7030TMCCL scaffolds accumulated more extracellular matrix after 56 days of culture (GAG: 20.1 ± 1, collagen: 35.5 ± 1.8 μg) compared to 5446DLLACL scaffolds (GAG: 13.2 ± 0.6, collagen: 6.2 ± 3.4 μg). Overall, the 7030TMCCL-based scaffolds were shown to be better suited for use as a load bearing soft tissue scaffold. PMID:24147621

  4. Buckling of Cracked Laminated Composite Cylindrical Shells Subjected to Combined Loading

    Allahbakhsh, Hamidreza; Shariati, Mahmoud

    2013-10-01

    A series of finite element analysis on the cracked composite cylindrical shells under combined loading is carried out to study the effect of loading condition, crack size and orientation on the buckling behavior of laminated composite cylindrical shells. The interaction buckling curves of cracked laminated composite cylinders subject to different combinations of axial compression, bending, internal pressure and external pressure are obtained, using the finite element method. Results show that the internal pressure increases the critical buckling load of the CFRP cylindrical shells and bending and external pressure decrease it. Numerical analysis show that axial crack has the most detrimental effect on the buckling load of a cylindrical shell and results show that for lower values of the axial compressive load and higher values of the external pressure, the buckling is usually in the global mode and for higher values of axial compressive load and lower levels of external pressure the buckling mode is mostly in the local mode.

  5. The Effect of Water Acrylate Dispersion on the Properties of Polymer-Carbon Nanotube Composites / Wpływ Wodnej Dyspersji Akrylanowej Na Właściwości Kompozytów Polimer-Nanorurki Węglowe

    Zygoń P.

    2015-12-01

    Full Text Available The paper presents properties of polymer composites reinforced with carbon nanotubes (CNT containing various mixtures of dispersion. Acrylates of different particle size and viscosity were used to produce composites. The mechanical strength of composites was determined by three-point bending tests. The roughness parameter of composites was determined with a profilometer and compared with the roughness parameter determined via atomic force microscopy (AFM. Also X-ray studies (phase composition analysis, crystallite sizes determination were carried out on these composites. Measurements of the surface topography using the Tapping Mode method were performed, acquiring the data on the height and on the phase imaging. The change of intensity, crystallite size and half-value width of main reflections originating from carbon within the composites have been determined using the X-ray analysis. The density of each obtained composite was determined as well as the resistivity at room temperature. The density of composites is quite satisfactory and ranges from 0.27 to 0.35 g/cm3. Different composites vary not only in strength but also in density. Different properties were achieved by the use of various dispersions. Carbon nanotubes constituting the reinforcement for a polymer composite improve the mechanical properties and conductivity composite.

  6. Delaminations in composite plates under transverse static loads - Experimental results

    Finn, Scott R.; He, Yi-Fei; Springer, George S.

    1992-01-01

    Tests were performed measuring the damage initiation loads and the locations, shapes, and sizes of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite-PEEK plates subjected to transverse static loads. The data were compared to the results of the Finn-Springer model, and good agreements were found between the measured and calculated delamination lengths and widths.

  7. Impact loading of an aluminum/alumina composite

    Johnson, J.; Hixson, R.; Gray, G

    1994-01-01

    The combined demands of increased strength and reduced weight in modern dynamic structural applications require improved understanding of composite materials subject to impact conditions. In order to isolate and identify individual contributions to composite material behavior under these conditions, an experimental and theoretical program was undertaken to examine dynamic behavior of an aluminum/alumina composite consisting of a 6061-T6 aluminum matrix containing elastic, spherical Al2O3 incl...

  8. Effects of simulated functional loading conditions on dentin, composite, and laminate structures.

    Walker, Mary P; Teitelbaum, Heather K; Eick, J David; Williams, Karen B

    2009-02-01

    Use of composite restorations continues to increase, tempered by more potential problems when placed in posterior dentition. Thus, it is essential to understand how these materials function under stress-bearing clinical conditions. Because mastication is difficult to replicate in the laboratory, cyclic loading is frequently used within in vitro evaluations but often employs traditional fatigue testing, which typically does not simulate occlusal loading because higher stresses and loading frequencies are used, so failure mechanisms may be different. This investigation utilized relevant parameters (specimen size, loading frequency) to assess the effects of cyclic loading on flexural mechanical properties and fracture morphology of (coronal) dentin, composite, and dentin-adhesive-composite "laminate" structures. Incremental monitoring of flexural modulus on individual beams over 60,000 loading cycles revealed a gradual increase across materials; post hoc comparisons indicated statistical significance only for 1 versus 60k cycles. Paired specimens were tested (one exposed to 60k loading cycles, one to static loading only), and comparisons of flexural modulus and strength showed statistically significantly higher values for cyclically loaded specimens across materials, with no observable differences in fracture morphology. Localized reorganization of dentin collagen and polymer chains could have increased flexural modulus and strength during cyclic loading, which may have implications toward the life and failure mechanisms of clinical restorations and underlying tooth structure. PMID:18823019

  9. An analytical solution for the elastoplastic response of a continuous fiber composite under uniaxial loading

    Lee, Jong-Won; Allen, David H.

    1990-01-01

    A continuous fiber composite is modelled by a two-element composite cylinder in order to predict the elastoplastic response of the composite under a monotonically increasing tensile loading parallel to fibers. The fibers and matrix are assumed to be elastic-perfectly plastic materials obeying Hill's and Tresca's yield criteria, respectively. Here, the composite behavior when the fibers yield prior to the matrix is investigated.

  10. FRP Composites Strengthening of Concrete Columns under Various Loading Conditions

    Azadeh Parvin

    2014-04-01

    Full Text Available This paper provides a review of some of the progress in the area of fiber reinforced polymers (FRP-strengthening of columns for several loading scenarios including impact load. The addition of FRP materials to upgrade deficiencies or to strengthen structural components can save lives by preventing collapse, reduce the damage to infrastructure, and the need for their costly replacement. The retrofit with FRP materials with desirable properties provides an excellent replacement for traditional materials, such as steel jacket, to strengthen the reinforced concrete structural members. Existing studies have shown that the use of FRP materials restore or improve the column original design strength for possible axial, shear, or flexure and in some cases allow the structure to carry more load than it was designed for. The paper further concludes that there is a need for additional research for the columns under impact loading senarios. The compiled information prepares the ground work for further evaluation of FRP-strengthening of columns that are deficient in design or are in serious need for repair due to additional load or deterioration.

  11. Assessment of particulate cellulose epoxy composites manufactured by JMFIL under impact load

    Srinivasababu, Nadendla

    2015-08-01

    Increase in environmental concern towards sustainable development invites the development of new materials which are eco-friendly to satisfy various engineering needs. The present work introduces a new manufacturing method i.e. "Just Mold Fill and Immediate Loading" to prepare epoxy composites reinforced at different contents of particulate cellulose. The fabricated composites specimens are post processed and machined, tested as per ASTM procedures under impact load.

  12. Structural investigation of composite wind turbine blade considering various load cases and fatigue life

    This study proposes a structural design for developing a medium scale composite wind turbine blade made of E-glass/epoxy for a 750 kW class horizontal axis wind turbine system. The design loads were determined from various load cases specified at the IEC61400-1 international specification and GL regulations for the wind energy conversion system. A specific composite structure configuration, which can effectively endure various loads such as aerodynamic loads and loads due to accumulation of ice, hygro-thermal and mechanical loads, was proposed. To evaluate the proposed composite wind turbine blade, structural analysis was performed by using the finite element method. Parametric studies were carried out to determine an acceptable blade structural design, and the most dominant design parameters were confirmed. In this study, the proposed blade structure was confirmed to be safe and stable under various load conditions, including the extreme load conditions. Moreover, the blade adapted a new blade root joint with insert bolts, and its safety was verified at design loads including fatigue loads. The fatigue life of a blade that has to endure for more than 20 years was estimated by using the well-known S-N linear damage theory, the service load spectrum, and the Spera's empirical equations. With the results obtained from all the structural design and analysis, prototype composite blades were manufactured. A specific construction process including the lay-up molding method was applied to manufacturing blades. Full-scale static structural test was performed with the simulated aerodynamic loads. From the experimental results, it was found that the designed blade had structural integrity. In addition, the measured results of deflections, strains, mass, and radial center of gravity agreed well with the analytical results. The prototype blade was successfully certified by an international certification institute, GL (Germanisher Lloyd) in Germany

  13. Performance of composite I-beams under axial compression and bending load modes

    Khalid, Y.A.; Ali, F.A.; Sahari, B.B.; Saad, E.M.A

    2005-04-15

    An experimental and finite-element analyses for glass/epoxy composite I-beams have been carried out. Four, six, eight and 10 layers of woven fabric glass/epoxy composite I-beams were fabricated by a hand lay-up (molding) process. Quasi-static axial crushing and bending loading modes were used for this investigation. The load-displacement response was obtained and the energy absorption values were calculated for all the composite I-beams. Three tests were done for each composite I-beams type and each loading case for the results conformation. The second part of this study includes the elastic behavior of composite I-beams of the same dimensions and materials using finite-element analysis. The woven fabric glass/epoxy composite I-beams mechanical properties have been obtained from tensile tests. Results from this investigation show that the load required and the specific energy absorption for composite I-beams under axial compression load were higher than those for three and four point bending. On the other hand, the loads required for composite I-beams under four point bending were higher than those for three point bending, while the specific energy absorption for composite I-beams under three point bending were higher than those for four point bending. The first crushing loads difference between the experimental and finite-element results fell in the 3.6-10.92% range for axial compression tests, while fell in the 1.44-12.99% and 4.94-22.0% range for three and four point bending, respectively.

  14. Controlled release and antibacterial activity of tetracycline hydrochloride-loaded bacterial cellulose composite membranes.

    Shao, Wei; Liu, Hui; Wang, Shuxia; Wu, Jimin; Huang, Min; Min, Huihua; Liu, Xiufeng

    2016-07-10

    Bacterial cellulose (BC) is widely used in biomedical applications. In this study, we prepared an antibiotic drug tetracycline hydrochloride (TCH)-loaded bacterial cellulose (BC) composite membranes, and evaluated the drug release, antibacterial activity and biocompatibility. The structure and morphology of the fabricated BC-TCH composite membranes were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TCH release results show that the incorporation of BC matrix to load TCH is able to control the release. In vitro antibacterial assay demonstrate that the developed BC-TCH composites displayed excellent antibacterial activity solely associated with the loaded TCH drug. More importantly, the BC-TCH composite membranes display good biocompatibility. These characteristics of BC-TCH composite membranes indicate that they may successfully serve as wound dressings and other medical biomaterials. PMID:27106158

  15. Aeroelastic Loads Modeling for Composite Aircraft Design Support

    Baluch, H.A.

    2009-01-01

    With regard to the simulation of structural vibrations and consequent aeroelastic loads in aircraft components, the use of elastic axis e.a as reference of vibrations is quite common. The e.a decouples the bending and torsion degrees of freedom (D.o.F) during the dynamic analysis. The use of the e.a

  16. Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

    Kermanshah, Hamid; Yasini, Esmail; Hoseinifar, Razieh

    2016-01-01

    Background: There are many concerns regarding the marginal seal of composite restorations, especially when composite restorations are subjected to cyclic loading. The aim of this study was to evaluate the effect of cyclic loading on the microleakage of silorane based composite compared with low shrinkage methacrylate-based composites in class V cavities. Materials and Methods: In this in vitro study, class V cavities were prepared on the facial and lingual surfaces of 48 human premolars (96 cavities). The teeth were randomly divided into four groups of 12 teeth (24 cavities) each and restored as follows: Group 1 (Siloran System Adhesive + Filtek P90), Group 2 (All Bond SE + Aelite LS Posterior), Group 3 (Futurabond NR + Grandio), and Group 4 (G-Bond + Kalore-GC). All the specimens were thermocycled for 2000 cycles (5-55°C) and then half of the specimens from each group, were Load cycled. All teeth were immersed in 0.5% basic fuchsine dye, sectioned, and observed under a stereomicroscope. Data were analyzed using Wilcoxon test, Kruskal–Wallis, and Mann–Whitney U-tests. P < 0.05 was considered as significant. Results: In both unloaded and loaded groups, no statistically significant differences were observed among four composites at the occlusal margin, but a significant difference in gingival microleakage was found between Aelite and silorane. Occlusal and gingival microleakage was not affected by cyclic loading in none of the four restorative materials. Conclusion: Silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except Aelite). In addition, cyclic loading did not affect the marginal microleakage of evaluated composite restorations. PMID:27274348

  17. Intermediate-scale Fire Performance of Composite Panels under Varying Loads

    Brown, Alexander [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jernigan, Dann A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dodd, Amanda B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-04-01

    New aircraft are being designed with increasing quantities of composite materials used in their construction. Different from the more traditional metals, composites have a higher propensity to burn. This presents a challenge to transportation safety analyses, as the aircraft structure now represents an additional fuel source involved in the fire scenario. Most of the historical fire testing of composite materials is aime d at studying kinetics, flammability or yield strength under fire conditions. Most of this testing is small - scale. Heterogeneous reactions are often length - scale dependent, and this is thought to be particularly true for composites which exhibit signific ant microscopic dynamics that can affect macro - scale behavior. We have designed a series of tests to evaluate composite materials under various structural loading conditions with a consistent thermal condition. We have measured mass - loss , heat flux, and temperature throughout the experiments. Several types of panels have been tested, including simple composite panels, and sandwich panels. The main objective of the testing was to understand the importance of the structural loading on a composite to its b ehavior in response to fire - like conditions. During flaming combustion at early times, there are some features of the panel decomposition that are unique to the type of loading imposed on the panels. At load levels tested, fiber reaction rates at later t imes appear to be independent of the initial structural loading.

  18. Preparation of anti-yellowing polyurethane-acrylate hybrid emulsion with composite polyols%多元醇复配制备耐黄变聚氨酯丙烯酸酯复合乳液

    沈慧芳; 严小妹; 刘天亮

    2011-01-01

    以异佛尔酮二异氰酸酯( IPDI)、混合多元醇、甲基丙烯酸甲酯(MMA)为主要原料合成了脂肪族聚氨酯丙烯酸酯复合乳液.混合多元醇由聚碳酸酯二醇( PCDL)、聚四亚甲基醚二醇(PTMEG)、聚醚二醇( N220)以不同比例复配而成.重点探讨了PCDL与N220、PTMEG与N220及PTMEG与PCDL复配比例对乳液、胶膜性能的影响.实验发现,当PTMEG与N220以相同质量比复配且控制硬段含量在60%时,得到贮存稳定性好,胶膜硬度高、耐水、耐溶剂性能好、耐黄变性优异的PUA复合乳液.%The aliphatic polyurethane-acrylate hybrid emulsions were prepared with isophorone diisocyanate (IPDI),composite polyols,and methyl methacrylate (MMA) as the main raw materials.The composite polyols were obtained by mixing polytetramethylene ether glycol (PTMEG) and polyether diol(N220),PTMEG and polycarbonate diol (PCDL),PCDL and N220 respectively at different ratio.The influences of mixing ratio of polyols on the properties of polyurethane-acrylate hybrid emulsions and their dry films were mainly discussed.The results showed that the polyurethane-acrylate hybrid emulsions had good stability,high film hardness,good water resistance and solvent resistance and excellent yollowing resistance when PTMEG and N220 were mixed by the same mass ratio and the content of hard segments was 60% in polyurethane prepolymer.

  19. General Factor Loadings and Specific Effects of the Differential Ability Scales, Second Edition Composites

    Maynard, Jennifer L.; Floyd, Randy G.; Acklie, Teresa J.; Houston, Lawrence, III

    2011-01-01

    The purpose of this study was to investigate the "g" loadings and specific effects of the core and diagnostic composite scores from the Differential Abilities Scales, Second Edition (DAS-II; Elliott, 2007a). Scores from a subset of the DAS-II standardization sample for ages 3:6 to 17:11 were submitted to principal factor analysis. Four composites,…

  20. Modeling the Tensile Strength of Carbon Fiber - Reinforced Ceramic - Matrix Composites Under Multiple Fatigue Loading

    Li, Longbiao

    2016-06-01

    An analytical method has been developed to investigate the effect of interface wear on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs) under multiple fatigue loading. The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure and the difference existed in the new and original interface debonded region. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress degradation model and fibers strength degradation model have been adopted to analyze the interface wear effect on the tensile strength of the composite subjected to multiple fatigue loading. Under tensile loading, the fibers failure probabilities were determined by combining the interface wear model and fibers failure model based on the assumption that the fiber strength is subjected to two - parameter Weibull distribution and the loads carried by broken and intact fibers satisfy the Global Load Sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength corresponding to multiple fatigue peak stress levels and different cycle number have been analyzed.

  1. DYNAMIC ANALYSIS OF UNDERGROUND COMPOSITE STRUCTURES UNDER EXPLOSION LOADING

    赵晓兵; 薛大为; 赵玉祥

    2004-01-01

    In selecting rational types of underground structures resisting explosion, in order to improve stress states of the structural section and make full use of material strength of each part of the section, the research method of composite structures is presented. Adopting the analysis method of micro-section free body, equilibrium equations, constraint equations and deformation coordination equations are given. Making use of the concept of generalized work and directly introducing Lagrange multiplier specific in physical meaning, the validity of the constructed generalized functional is proved by using variation method. The rational rigidity matching relationship of composite structure section is presented through example calculations.

  2. Mechanical behavior of a continuous fiber reinforced aluminum matrix composite subjected to transverse and thermal loading

    Jansson, S.; Leckie, F. A.

    1991-01-01

    The transverse properties of an aluminum alloy metal matrix composite reinforced by continuous alumina fibers were investigated. The composite is subjected to both mechanical and cyclic thermal loading. The results of an experimental program indicate that the shakedown concept of structural mechanics provides a means of describing the material behavior. When the loading conditions are within the shakedown region, the material finally responds in an elastic manner after initial plastic response, and for loading conditions outside the shakedown region, the material exhibits a rapid incremental plastic strain accumulation. The failure strain varies by an order of magnitude according to the operating conditions. Hence, for high mechanical and low thermal loading, the failure strains is small; for low mechanical and high thermal loading, the failure strain is large.

  3. Correlation of gas permeability with polymer loading on radiation-induced wood composites

    Selected local hardwoods and their wood polymer combinations or composites (WPC) were tested for their specific permeability in the longitudinal direction and polymer loading respectively. WPC were prepared by polymerizing methyl methacrylate monomer in situ in oven-dried woods by gamma radiation. Correlation studies between permeability of the oven-dried hardwood samples and two other factors, extractive content and polymer loading, were made. A significantly high correlation was obtained between permeability and polymer loading. Low correlation was observed between extractive content and permeability as well as polymer loading. The high permeability of most hardwoods can be attributed to their large vessel sizes and absence of any vessel deposits. (author)

  4. Diet and Environment Shape Fecal Bacterial Microbiota Composition and Enteric Pathogen Load of Grizzly Bears

    Schwab, Clarissa; Cristescu, Bogdan; Northrup, Joseph M.; Stenhouse, Gordon B.; Gänzle, Michael

    2011-01-01

    Background Diet and environment impact the composition of mammalian intestinal microbiota; dietary or health disturbances trigger alterations in intestinal microbiota composition and render the host susceptible to enteric pathogens. To date no long term monitoring data exist on the fecal microbiota and pathogen load of carnivores either in natural environments or in captivity. This study investigates fecal microbiota composition and the presence of pathogenic Escherichia coli and toxigenic cl...

  5. Bearing capacity investigation of pin-ended composite columns with eccentricity loading using finite element simulation

    Ahmed Abdulhaq; W.H. WAN BADARUZZAMAN

    2011-01-01

    In this paper, a complete non-linear finite element model that could represent the behaviour of the composite columns tested under axial compression in the laboratory was developed. A numerical analyses study was presented based on experimental results for investigating the effects of introducing column head on the structural behaviour of 10 finite element models of fully encased composite columns with embedded I-beam. Effects of parameters such as length of composite columns and loading cond...

  6. Acrylic purification and coatings

    ,

    2012-01-01

    Radon (Rn) and its decay daughters are a well-known source of background in direct WIMP detection experiments, as either a Rn decay daughter or an alpha particle emitted from a thin inner surface layer of a detector could produce a WIMP-like signal. Different surface treatment and cleaning techniques have been employed in the past to remove this type of contamination. A new method of dealing with the problem has been proposed and used for a prototype acrylic DEAP-1 detector. Inner surfaces of the detector were coated with a layer of ultra pure acrylic, meant to shield the active volume from alphas and recoiling nuclei. An acrylic purification technique and two coating techniques are described: a solvent-borne (tested on DEAP-1) and solvent-less (being developed for the full scale DEAP-3600 detector).

  7. Delaminations in composite plates under transverse impact loads - Experimental results

    Finn, Scott R.; He, Ye-Fei; Springer, George S.

    1993-01-01

    Tests were performed measuring the locations and geometries of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite/PEEK plates subjected to transverse impact loads. The data provide specific information on the effects of impactor velocity, impactor mass, material, thickness of back ply group, difference in fiber orientation between adjacent ply groups, plate thickness, and impactor nose radius. The data were compared to the results of the Finn-Springer model. The model was found to describe the data with reasonable accuracy.

  8. Cyclic loadings on steel and lightweight concrete composite beams

    Valente, Isabel; Cruz, Paulo J. S.

    2006-01-01

    This communication describes the experimental cyclic tests performed on steel and high strength lightweight concrete composite beams, at Universidade do Minho, Portugal. The experimental study involves tests on simply supported beams, all with the same geometrical disposition, supports and materials. Headed studs are used to provide the connection between the steel profile and the lightweight concrete slab. The parameters in study are the stud disposition and the number and range of the...

  9. Properties of natural rubber/attapulgite composites prepared by latex compounding method: Effect of filler loading

    Muttalib, Siti Nadzirah Abdul, E-mail: sitinadzirah.amn@gmail.com; Othman, Nadras, E-mail: srnadras@usm.my; Ismail, Hanafi, E-mail: ihanafi@usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

    2015-07-22

    This paper reports on the effect of filler loading on properties of natural rubber (NR)/attapulgite (ATP) composites. The NR/ATP composites were prepared by latex compounding method. It is called as masterbatch. The masterbatch was subsequently added to the NR through melt mixing process. The vulcanized NR/ATP composites were subjected to mechanical, swelling and morphological tests. All the results were compared with NR/ATP composites prepared by conventional system. The composites from masterbatch method showed better results compared to composites prepared by conventional method. They have higher tensile properties, elongation at break and tear strength. The images captured through scanning electron microscopy test revealed the improvement of tensile strength in masterbatch NR/ATP composites. It can be seen clearly that masterbatch NR/ATP have better filler dispersion compared to conventional method NR/ATP composites.

  10. Properties of natural rubber/attapulgite composites prepared by latex compounding method: Effect of filler loading

    This paper reports on the effect of filler loading on properties of natural rubber (NR)/attapulgite (ATP) composites. The NR/ATP composites were prepared by latex compounding method. It is called as masterbatch. The masterbatch was subsequently added to the NR through melt mixing process. The vulcanized NR/ATP composites were subjected to mechanical, swelling and morphological tests. All the results were compared with NR/ATP composites prepared by conventional system. The composites from masterbatch method showed better results compared to composites prepared by conventional method. They have higher tensile properties, elongation at break and tear strength. The images captured through scanning electron microscopy test revealed the improvement of tensile strength in masterbatch NR/ATP composites. It can be seen clearly that masterbatch NR/ATP have better filler dispersion compared to conventional method NR/ATP composites

  11. Research on torsional friction behavior and fluid load support of PVA/HA composite hydrogel.

    Chen, Kai; Zhang, Dekun; Yang, Xuehui; Cui, Xiaotong; Zhang, Xin; Wang, Qingliang

    2016-09-01

    Hydrogels have been extensively studied for use as synthetic articular cartilage. This study aimed to investigate (1) the torsional friction contact state and the transformation mechanism of PVA/HA composite hydrogel against CoCrMo femoral head and (2) effects of load and torsional angle on torsional friction behavior. The finite element method was used to study fluid load support of PVA/HA composite hydrogel. Results show fluid loss increases gradually of PVA/HA composite hydrogel with torsional friction time, leading to fluid load support decreases. The contact state changes from full slip state to stick-slip mixed state. As the load increases, friction coefficient and adhesion zone increase gradually. As the torsional angle increases, friction coefficient and slip trend of the contact interface increase, resulting in the increase of the slip zone and the reduction of the adhesion zone. Fluid loss increases of PVA/HA composite hydrogel as the load and the torsional angle increase, which causes the decrease of fluid load support and the increase of friction coefficient. PMID:27209115

  12. Stress Corrosion Cracking of Basalt/Epoxy Composites under Bending Loading

    Shokrieh, Mahmood M.; Memar, Mahdi

    2010-04-01

    The purpose of this research is to study the stress corrosion behavior of basalt/epoxy composites under bending loading and submerged in 5% sulfuric acid corrosive medium. There are limited numbers of research in durability of fiber reinforced polymer composites. Moreover, studies on basalt fibers and its composites are very limited. In this research, mechanical property degradation of basalt/epoxy composites under bending loading and submerged in acidic corrosive medium is investigated. Three states of stress, equal to 30%, 50% and 70% of the ultimate strength of composites, are applied on samples. High stress states are applied to the samples to accelerate the testing procedure. Mechanical properties degradation consists of bending strength, bending modulus of elasticity and fracture energy of samples are examined. Also, a normalized strength degradation model for stress corrosion condition is presented. Finally, microscopic images of broken cross sections of samples are examined.

  13. Finite Element Analysis of Ultimate Load Capacity of Slender Concrete-Filled Steel Composite Columns

    Alireza Bahrami

    2011-01-01

    Full Text Available Ultimate load capacity of slender concrete-filled steel composite columns is investigated in this paper. Nonlinear analyses are done by the use of finite element software, LUSAS, to study the ultimate axial load behaviour of the columns. Verification of the finite element modelling is done by comparing the result with the corresponding experimental result reported by other researchers. Analyses are carried out to assess different shapes and number of cold-formed steel sheeting stiffeners with various thicknesses of cold-formed steel sheets and their effects on the behaviour and ultimate axial load capacity of the columns. The results are presented in the form of axial load-normalized axial shortening plots. It is demonstrated that the ultimate axial load capacity of the slender concrete-filled steel composite columns can be accurately predicted by proposed finite element modelling. Obtained results from the study show that various thicknesses of cold-formed steel sheets, and different shapes and number of stiffeners influence the ultimate axial load capacity and behaviour of the columns. Also, the ultimate axial load capacity of the columns is improved by increase of number of stiffeners. Moreover, increase of thickness of cold-formed steel sheet enhances the ultimate axial load capacity.

  14. High-Density Protein Loading on Hierarchically Porous Layered Double Hydroxide Composites with a Rational Mesostructure.

    Tokudome, Yasuaki; Fukui, Megu; Tarutani, Naoki; Nishimura, Sari; Prevot, Vanessa; Forano, Claude; Poologasundarampillai, Gowsihan; Lee, Peter D; Takahashi, Masahide

    2016-09-01

    Hierarchically porous biocompatible Mg-Al-Cl-type layered double hydroxide (LDH) composites containing aluminum hydroxide (Alhy) have been prepared using a phase-separation process. The sol-gel synthesis allows for the hierarchical pores of the LDH-Alhy composites to be tuned, leading to a high specific solid surface area per unit volume available for high-molecular-weight protein adsorptions. A linear relationship between the effective surface area, SEFF, and loading capacity of a model protein, bovine serum albumin (BSA), is established following successful control of the structure of the LDH-Alhy composite. The threshold of the mean pore diameter, Dpm, above which BSA is effectively adsorbed on the surface of LDH-Alhy composites, is deduced as 20 nm. In particular, LDH-Alhy composite aerogels obtained via supercritical drying exhibit an extremely high capacity for protein loading (996 mg/g) as a result of a large mean mesopore diameter (>30 nm). The protein loading on LDH-Alhy is >14 times that of a reference LDH material (70 mg/g) prepared via a standard procedure. Importantly, BSA molecules pre-adsorbed on porous composites were successfully released on soaking in ionic solutions (HPO4(2-) and Cl(-) aqueous). The superior capability of the biocompatible LDH materials for loading, encapsulation, and releasing large quantities of proteins was clearly demonstrated. PMID:27501777

  15. Experimental and Numerical Analysis of Notched Composites Under Tension Loading

    Aidi, Bilel; Case, Scott W.

    2015-12-01

    Experimental quasi-static tests were performed on center notched carbon fiber reinforced polymer (CFRP) composites having different stacking sequences made of G40-600/5245C prepreg. The three-dimensional Digital Image Correlation (DIC) technique was used during quasi-static tests conducted on quasi-isotropic notched samples to obtain the distribution of strains as a function of applied stress. A finite element model was built within Abaqus to predict the notched strength and the strain profiles for comparison with measured results. A user-material subroutine using the multi-continuum theory (MCT) as a failure initiation criterion and an energy-based damage evolution law as implemented by Autodesk Simulation Composite Analysis (ASCA) was used to conduct a quantitative comparison of strain components predicted by the analysis and obtained in the experiments. Good agreement between experimental data and numerical analyses results are observed. Modal analysis was carried out to investigate the effect of static damage on the dominant frequencies of the notched structure using the resulted degraded material elements. The first in-plane mode was found to be a good candidate for tracking the level of damage.

  16. Hyperbranched urethane-acrylates

    Tasić Srba

    2004-01-01

    Full Text Available The synthesis, characterization and UV-curing of hyperbranched urethaneacrylates (HB-UA were investigated in this study. They were evaluated as oli-gomers in model UV curable coatings. HB-UAs were synthesized by reaction of an aliphatic hyperbranched polyester of the second generation (HBRG2 and an isocyanate adduct, obtained by the reaction of isophoronediisocyana-te and different hydroxy alkyl acrylates. Their thermal properties and viscosities depend on the degree of modification of HBRG2 and the type of hydroxy alkyl acrylate used. The introduction of a flexible alkoxylated spacer between the HBP core and acrylate end groups reduces steric hindrance by moving the cross linkable acrylate groups away from the HBP core and increase its reactivity. Due to the presence of abstractable H-atoms in the α-position to the ether links, HB-UAs based on poly(ethylene oxide monoacrylate are very reactive and do not show oxygen inhibition. The obtained coatings combine a high cross linking density with flexible segments between the cross links, which results in a good compromise between hardness and flexibility and have the potential to be used in different UV-curing applications.

  17. Combination of modified mixing technique and low frequency ultrasound to control the elution profile of vancomycin-loaded acrylic bone cement

    Wendling, A.; Mar, D.; Wischmeier, N.; Anderson, D.

    2016-01-01

    Objectives The objective of this study was to determine if combining variations in mixing technique of antibiotic-impregnated polymethylmethacrylate (PMMA) cement with low frequency ultrasound (LFUS) improves antibiotic elution during the initial high phase (Phase I) and subsequent low phase (Phase II) while not diminishing mechanical strength. Methods Three batches of vancomycin-loaded PMMA were prepared with different mixing techniques: a standard technique; a delayed technique; and a control without antibiotic. Daily elution samples were analysed using flow injection analysis (FIA). Beginning in Phase II, samples from each mix group were selected randomly to undergo either five, 15, 45, or 0 minutes of LFUS treatment. Elution amounts between LFUS treatments were analysed. Following Phase II, compression testing was done to quantify strength. A-priori t-tests and univariate ANOVAs were used to compare elution and mechanical test results between the two mix groups and the control group. Results The delayed technique showed a significant increase in elution on day one compared with the standard mix technique (p DOI: 10.1302/2046-3758.52.2000412 PMID:26843512

  18. Compressive damage mechanism of GFRP composites under off-axis loading: Experimental and numerical investigations

    Zhou, H.W.; Li, H.Y.; Gui, L.L.;

    2013-01-01

    angles between the loading vector and fiber direction were carried out under scanning electron microscopy (SEM) in situ observation. The damage mechanisms as well as stress strain curves were obtained in the experiments. It was shown that the compressive strength of composites drastically reduces when...... the angle between the fiber direction and the loading vector goes from 0° to 45° (by 2.3–2.6 times), and then slightly increases (when the angle approaches 80–90°). At the low angles between the fiber and the loading vector, fiber buckling and kinking are the main mechanisms of fiber failure....... With increasing the angle between the fiber and applied loading, failure of glass fibers is mainly controlled by shear cracking. For the computational analysis of the damage mechanisms, 3D multifiber unit cell models of GFRP composites and X-FEM approach to the fracture modeling were used. The computational...

  19. Composite slab behavior and strength analysis under static and dynamic loads

    Florin Radu HARIGA

    2012-07-01

    Full Text Available Steel-framed buildings are typically constructed using steel-deck-reinforced concrete floor slabs. The in-plane (or diaphragm strength and stiffness of the floor system are frequently utilized in the lateral load-resisting system design. This paper presents the results of an experimental research program in which four full size composite diaphragms were vertically loaded to the limit state, under static or dynamic loads. Two test specimens were provided with longitudinal steel-deck ribs, and the other two specimens with cross steel-deck ribs. Typical composite diaphragm limit states are described, and the controlling limit state for each of the full size tests is indicated. The interaction effects between the reinforced concrete slab and the steel girder on the composite slab strength and stiffness were mainly studied.

  20. Finite Element Analysis of Ultimate Load Capacity of Slender Concrete-Filled Steel Composite Columns

    Alireza Bahrami; Wan Hamidon Wan Badaruzzaman; Siti Aminah Osman

    2011-01-01

    Ultimate load capacity of slender concrete-filled steel composite columns is investigated in this paper. Nonlinear analyses are done by the use of finite element software, LUSAS, to study the ultimate axial load behaviour of the columns. Verification of the finite element modelling is done by comparing the result with the corresponding experimental result reported by other researchers. Analyses are carried out to assess different shapes and number of cold-formed steel sheeting stiffeners with...

  1. Influence of metal loading on hydrocracking of rapeseed oil using bifunctional micro-/mesoporous composite materials

    Gille, T.; Busse, O.; Reschetilowski, W. [Technische Univ. Dresden (Germany). Inst. of Industrial Chemistry

    2013-11-01

    Hydrocracking of rapeseed oil has been investigated in a fixed bed reactor under integral conditions. A synthesized micro-/mesoporous composite material Al-MCM-41/ZSM-5 modified by different metal loadings (NiMo, PtNiMo, Pt) was used as catalyst system. It could be demonstrated that the support material and their metal loading influence the product selectivity as well as the deactivation tendencies of the catalyst sample. (orig.)

  2. Evaluation of flawed composite structural components under static and cyclic loading. [fatigue life of graphite-epoxy composite materials

    Porter, T. R.

    1979-01-01

    The effects of initial defects on the fatigue and fracture response of graphite-epoxy composite laminates are presented. The structural laminates investigated were a typical angle ply laminate, a polar/hoop wound pressure vessel laminate, and a typical engine fan blade laminate. Defects investigated were full and half penetration circular holes, full and half penetration slits, and countersink holes. The effects of the defect size and type on the static fracture strength, fatigue performance, and residual static strength are shown as well as the results of loadings on damage propagation in composite laminates. The data obtained were used to define proof test levels as a qualification procedure in composite structure subjected to cyclic loading.

  3. In vitro and in vivo efficacy of doxorubicin loaded biodegradable semi-interpenetrating hydrogel implants of poly (acrylic acid)/gelatin for post surgical tumor treatment

    The paper describes the preparation and evaluation of doxorubicin loaded semi-interpenetrating polymeric hydrogel network of polyacrylic acid (PAc) and gelatin (G). Post surgical antitumor efficacy and biodistribution of doxorubicin from the implanted degradable hydrogels was investigated on Ehrlich's ascites tumor model using albino mice. Polycaprolactone diacrylate (PCL-DAr) was employed as a crosslinking agent for PAc chains whereas G was kept free. The effect of crosslinking concentration on various physico-chemical properties such as thermal behavior, swelling, degradation behavior, drug release and polymer–polymer interactions was investigated by various physico-chemical tools. Semi-interpenetrating polymeric networks (IPNs) with 0.2 mol% crosslinking concentration showed degradation within 20 days in phosphate buffer (pH 6.5). To determine the in vivo anticancer efficacy, placebo and drug laden cylindrical implants (65 ± 5 µg/implant of 10 mg) were implanted in tumor cavity post tumor excision. After predetermined time intervals (day 7, 11, 14, 20 and 25), drug biodistribution was assessed in tumor, tumor periphery, residual hydrogel and all vital organs i.e. liver, spleen, kidney, heart, lung and blood (spectrofluorimetrically). The drug distribution study showed the concentration of drug in the tumor, tumor periphery and residual hydrogel decreased with increasing time; on the 7th day, drug concentration was highest while, on the 25th day, it was negligible; however, insignificant quantities of the drug was found in vital organs. Histological examination revealed no sign of tumor recurrence until the 25th day with 100% necrosis and slight inflammation in treated the group. In vivo results established that these biodegradable implants can be utilized as post surgical therapy for solid tumors. (paper)

  4. Optimization Formulations for the Maximum Nonlinear Buckling Load of Composite Structures

    Lindgaard, Esben; Lund, Erik

    2011-01-01

    This paper focuses on criterion functions for gradient based optimization of the buckling load of laminated composite structures considering different types of buckling behaviour. A local criterion is developed, and is, together with a range of local and global criterion functions from literature......, benchmarked on a number of numerical examples of laminated composite structures for the maximization of the buckling load considering fiber angle design variables. The optimization formulations are based on either linear or geometrically nonlinear analysis and formulated as mathematical programming problems...

  5. Loading-dependent elemental composition of α-pinene SOA particles

    J. E. Shilling; Chen, Q; S. M. King; Rosenoern, T.; Kroll, J. H.; Worsnop, D. R.; Decarlo, P. F.; A. C. Aiken; D. Sueper; Jimenez, J. L.; Martin, S. T.

    2009-01-01

    The chemical composition of secondary organic aerosol (SOA) particles, formed by the dark ozonolysis of α-pinene, was characterized by a high-resolution time-of-flight aerosol mass spectrometer. The experiments were conducted using a continuous-flow chamber, allowing the particle mass loading and chemical composition to be maintained for several days. The organic portion of the particle mass loading was varied from 0.5 to >140 μg/m3 by adjusting the concentration of ...

  6. Loading-dependent elemental composition of α-pinene SOA particles

    Jimenez, J. L.; D. Sueper; A. C. Aiken; Kroll, J. H.; Worsnop, D. R.; Decarlo, P. F.; S. M. King; Rosenoern, T.; J. E. Shilling; Chen, Q; Martin, S. T.

    2008-01-01

    The chemical composition of secondary organic aerosol (SOA) particles, formed by the dark ozonolysis of α-pinene, was characterized by a high-resolution time-of-flight aerosol mass spectrometer. The experiments were conducted using a continuous-flow chamber, allowing the particle mass loading and chemical composition to be maintained for several days. The organic portion of the particle mass loading was varied from 0.5 to >140 μg/m3 by adjusting the concentration of reacted α-pinene ...

  7. Shock-loading response of 6061-T6 aluminum-alumina metal-matrix composites

    Vecchio, K.; Gray, G

    1994-01-01

    The purpose of this research is to systematically study the influence of peak-shock pressure and second-phase reinforcement on the structure/property response of shock-loaded 6061-T6 Al-alumina composites. The reload stress-strain response of monolithic 6061-T6 Al showed no increased shock hardening compared to the unshocked material deformed to an equivalent strain. The reload stress-strain response of the shock-loaded 6061-T6 Al-alumina composites exhibits a lower reload yield strength than...

  8. Synthesis and photocatalytic activity of carbon spheres loaded Cu{sub 2}O/Cu composites

    Li, Yinhui, E-mail: lillian09281@hotmail.com; Zhao, Mengyao; Zhang, Na; Li, Ruijuan; Chen, Jianxin

    2015-09-15

    Highlights: • Carbon spheres loaded Cu{sub 2}O/Cu composites are obtained by hydrothermal process. • Cu{sub 2}O/Cu nanocrystals grow on the surface of carbon spheres. • The composites with core–shell structure show highly photo-catalytic activity. • The composites can degrade methyl orange under simulated solar light irradiation. • The composites can be used to treat dye wastewater or organic pollutants. - Abstract: In this work, using amylose as carbon source and cupric acetate as copper source, carbon spheres loaded Cu{sub 2}O/Cu composites were obtained by hydrothermal synthesis. The effects of the molar ratios between glucose and Cu(II), and hydrothermal time on the morphology and sizes of the composites were investigated. The result of photocatalytic experiments demonstrated that the composites could degrade methyl orange in aqueous solution under simulated solar light irradiation. The highest degradation rate was achieved to 93.83% when the composites were prepared by hydrothermal synthesis at 180 °C for 16 h and the molar ratio between glucose and Cu(II) was 10/1. The composites, as new and promising materials, can be used to treat dye wastewater or other organic pollutants.

  9. Synthesis and photocatalytic activity of carbon spheres loaded Cu2O/Cu composites

    Highlights: • Carbon spheres loaded Cu2O/Cu composites are obtained by hydrothermal process. • Cu2O/Cu nanocrystals grow on the surface of carbon spheres. • The composites with core–shell structure show highly photo-catalytic activity. • The composites can degrade methyl orange under simulated solar light irradiation. • The composites can be used to treat dye wastewater or organic pollutants. - Abstract: In this work, using amylose as carbon source and cupric acetate as copper source, carbon spheres loaded Cu2O/Cu composites were obtained by hydrothermal synthesis. The effects of the molar ratios between glucose and Cu(II), and hydrothermal time on the morphology and sizes of the composites were investigated. The result of photocatalytic experiments demonstrated that the composites could degrade methyl orange in aqueous solution under simulated solar light irradiation. The highest degradation rate was achieved to 93.83% when the composites were prepared by hydrothermal synthesis at 180 °C for 16 h and the molar ratio between glucose and Cu(II) was 10/1. The composites, as new and promising materials, can be used to treat dye wastewater or other organic pollutants

  10. Buckling of Laminated Composite Stiffened Panels Subjected to Linearly Varying In-Plane Edge Loading

    Mallela, Upendra K.; Upadhyay, Akhil

    2014-01-01

    The presence of in-plane loading may cause buckling of stiffened panels. An accurate knowledge of critical buckling load and mode shapes is essential for reliable and lightweight structural design. This paper presents parametric studies on simply supported laminated composite blade-stiffened panels subjected to linearly varying in-plane edge/compressive loading. Studies are carried out by changing the panel orthotropy ratio, stiffener depth, pitch length (number of stiffeners), smeared extensional stiffness ratio of stiffener to that of the plate and load distribution parameter. Based on the studies, a few important parameters influencing the buckling behavior are identified and their significance is discussed. Further, the interaction equations for combined loadings are validated by carrying out numerical studies.

  11. Experimental Investigation on Laminated Composite Leaf springs Subjected to Cyclic Loading

    S.Rajesh

    2014-03-01

    Full Text Available An automobile industry have an interest in replacement of conventional leaf spring with composite leaf spring to get better performance with less weight. This paper deals with by replacing the conventional leaf spring with composite leaf spring. The dimensions of an existing conventional steel leaf spring of a light commercial vehicle were taken to fabricate the special die which is further used to manufacture the composite leaf spring. A single leaf with constant cross sectional area similar to that of conventional leaf spring(CLS in each case such as bidirectional glass fiber reinforced plastic (GFRP, bidirectional carbon fiber reinforced plastic (CFRP, bidirectional carbon-glass reinforced plastic (C-GFRP and bidirectional glass-carbon reinforced plastic (G-CFRP were fabricated by hand layup technique and tested by universal testing machine. By using universal testing machine, load per deflection and maximum load that a leaf spring can withstand were measured. The cyclic loading with specific duration was given to the above mentioned composite leaf springs by using a laboratory designed loading set up through milling machine. From the experimented results it was observed that if conventional leaf springs are replaced by composite leaf springs an appropriate amount of weight reduction and there by improved vehicle performance could be achieved.

  12. DELAMINATION FORMATION AND DELAMINATION PROPAGATION OF COMPOSITE LAMINATES UNDER COMPRESSIVE FATIGUE LOADING

    2000-01-01

    Fatigue tests of the smooth composite laminates and the notched composite laminates under compressive cyclic loading have been carried out. The damage mechanism is discussed and analyzed. Damage evolution is monitored using stiffness decay. From these tests, it is found that the initial delamination occurs at the free boundary of smooth specimens, or the notch boundary of notched specimens, subjected to the compression-compression cyclic load. A point of view in relation to two-phases of compression fatigue delamination of composites is proposed, namely, compression-compression delamination consists of the delamination formation phase and the delamination propagation, and there is a "damage transition point" to separate this two-phases. Furthermore, an empirical modulus degradation formula and its parameters fitting method are presented. According to the test data handling results, it is shown that this formula is univocal and can fit the test data conveniently. In addition, two kinds of new anti-buckling devices are designed for these tests. At last, the E-N curves, the D-N curves and the S-N curve of the smooth carbon fiber reinforced composite laminates of T300/648C are determined to predict the fatigue life of the notched composite laminate. And the E-N curve of the notched specimens at the given load ratio R=10 and minimum load P min=-0.45 kN is also measured to verify the estimated result of fatigue life.

  13. Self-Sensing of Damage Progression in Unidirectional Multiscale Hierarchical Composites Subjected to Cyclic Tensile Loading.

    Ku-Herrera, J J; Pacheco-Salazar, O F; Ríos-Soberanis, C R; Domínguez-Rodríguez, G; Avilés, F

    2016-01-01

    The electrical sensitivity of glass fiber/multiwall carbon nanotube/vinyl ester hierarchical composites containing a tailored electrically-percolated network to self-sense accumulation of structural damage when subjected to cyclic tensile loading-unloading is investigated. The hierarchical composites were designed to contain two architectures differentiated by the location of the multiwall carbon nanotubes (MWCNTs), viz. MWCNTs deposited on the fibers and MWCNTs dispersed within the matrix. The changes in electrical resistance of the hierarchical composites are associated to their structural damage and correlated to acoustic emissions. The results show that such tailored hierarchical composites are able to self-sense damage onset and accumulation upon tensile loading-unloading cycles by means of their electrical response, and that the electrical response depends on the MWCNT location. PMID:26999158

  14. Self-Sensing of Damage Progression in Unidirectional Multiscale Hierarchical Composites Subjected to Cyclic Tensile Loading

    J. J. Ku-Herrera

    2016-03-01

    Full Text Available The electrical sensitivity of glass fiber/multiwall carbon nanotube/vinyl ester hierarchical composites containing a tailored electrically-percolated network to self-sense accumulation of structural damage when subjected to cyclic tensile loading-unloading is investigated. The hierarchical composites were designed to contain two architectures differentiated by the location of the multiwall carbon nanotubes (MWCNTs, viz. MWCNTs deposited on the fibers and MWCNTs dispersed within the matrix. The changes in electrical resistance of the hierarchical composites are associated to their structural damage and correlated to acoustic emissions. The results show that such tailored hierarchical composites are able to self-sense damage onset and accumulation upon tensile loading-unloading cycles by means of their electrical response, and that the electrical response depends on the MWCNT location.

  15. TENSILE AND FLEXURAL STUDIES ON GLASS - CARBON HYBRID COMPOSITES SUBJECTED TO LOW FREQUENCY CYCLIC LOADING

    K. Poyyathappan

    2014-03-01

    Full Text Available Glass fiber reinforced polymeric composite (GFRP, Carbon fiber reinforced polymeric composite (CFRP, glass-carbon-glass, carbon-glass-carbon hybrid composite laminates have been prepared by hand layup method. The test specimens have been prepared according to ASTM standard size to carry out the tensile and flexural tests. Six specimens with 0±90° orientation have been prepared for both the tests. The specimens have been subjected to low frequency cyclic load for specific duration prior to the flexural bending analysis. Three point bend method has been adopted to find out the flexural strength and flexural modulus. Flexural strength and modulus have been calculated from the load deflection curve obtained from the tensometer for respective specimens. The results show that the hybrid composites have better flexural properties than the GFRP.

  16. Effect of Nanoclay on Thermal Conductivity and Flexural Strength of Polymethyl Methacrylate Acrylic Resin

    Tahereh Ghaffari; Ali Barzegar; Fahimeh Hamedi Rad; Elnaz Moslehifard

    2016-01-01

    Statement of the Problem: The mechanical and thermal properties of polymethyl methacrylate (PMMA) acrylic resin should be improved to counterweigh its structural deficiencies. Purpose: The aim of this study was to compare the flexural strength and thermal conductivity of conventional acrylic resin and acrylic resin loaded with nanoclay. Materials and Method: The methacrylate monomer containing the 0.5, 1 and 2 wt% of nanoclay was placed in an ultrasonic probe and mixed with the PMMA p...

  17. Load transfer and deformation mechanisms in carbon nanotube-polystyrene composites

    Qian, D.; Dickey, E. C.; Andrews, R.; Rantell, T.

    2000-05-01

    Multiwall carbon nanotubes have been dispersed homogeneously throughout polystyrene matrices by a simple solution-evaporation method without destroying the integrity of the nanotubes. Tensile tests on composite films show that 1 wt % nanotube additions result in 36%-42% and ˜25% increases in elastic modulus and break stress, respectively, indicating significant load transfer across the nanotube-matrix interface. In situ transmission electron microscopy studies provided information regarding composite deformation mechanisms and interfacial bonding between the multiwall nanotubes and polymer matrix.

  18. Self-Sensing of Damage Progression in Unidirectional Multiscale Hierarchical Composites Subjected to Cyclic Tensile Loading

    Ku-Herrera, J. J.; Pacheco-Salazar, O. F.; Ríos-Soberanis, C. R.; G. Domínguez-Rodríguez; Avilés, F.

    2016-01-01

    The electrical sensitivity of glass fiber/multiwall carbon nanotube/vinyl ester hierarchical composites containing a tailored electrically-percolated network to self-sense accumulation of structural damage when subjected to cyclic tensile loading-unloading is investigated. The hierarchical composites were designed to contain two architectures differentiated by the location of the multiwall carbon nanotubes (MWCNTs), viz. MWCNTs deposited on the fibers and MWCNTs dispersed within the matrix. T...

  19. Finite element analysis of composite tubes with integral ends subjected to bending loads

    Adams, Michael B.

    1995-01-01

    An analytical investigation was perfonned to study the effect of applied bending loads on laminated composite tubes. Elasticity-based linear models were developed using finite element software to predict stresses within the individual plies of the tubes. The tubes under investigation were graphite/epoxy laminated composites with a stacking sequence of [0/-45/+45/90/90/+45/ -45/0] X 2 (Sixteen plies per tube). End pieces of isotropic titanium were integrally constructed with bon...

  20. Finite Element Analysis of Composite Hardened Walls Subjected to Blast Loads

    Girum S. Urgessa

    2009-01-01

    Problem statement: There is currently no standard design guideline to determine the number of composites needed to retrofit masonry walls in order to withstand a given explosion. Past design approaches were mainly based on simplified single-degree-of-freedom analysis. A finite element analysis was conducted for concrete masonry walls hardened with composites and subjected to short duration blast loads. Approach: The analysis focused on displacement time history responses which form the basis ...

  1. Study of the damaging mechanisms of a copper / carbon - carbon composite under thermomechanical loading

    The purpose of this work is to understand and to identify the damaging mechanisms of Carbon-Carbon composite bonded to copper under thermomechanical loading. The study of the composite allowed the development of non-linear models. These ones have been introduced in the finite elements analysis code named CASTEM2000. They have been validated according to a correlation between simulation and mechanical tests on multi-material samples. These tests have also permitted us to better understand the behaviour of the bonding between composite and copper (damaging and fracture modes for different temperatures) under shear and tensile loadings. The damaging mechanisms of the bond under thermomechanical loading have been studied and identified according to microscopic observations on mock-ups which have sustained thermal cycling tests: some cracks appear in the composite, near the bond between the composite and the copper. The correlation between numerical and experimental results have been improved because of the reliability of the composite modelization, the use of residual stresses and the results of the bond mechanical characterization. (author)

  2. Study of the damaging mechanisms of a carbon - carbon composite bonded to copper under thermomechanical loading

    The purpose of this work is to understand and to identify the damaging mechanisms of Carbon-Carbon composite bonded to copper under thermomechanical loading. The study of the composite allowed the development of non-linear models. These ones have been introduced in the finite elements analysis code named CASTEM 2000. They have been validated according to a correlation between simulation and mechanical tests on multi-material samples. These tests have also permitted us to better understand the behaviour of the bonding between composite and copper (damaging and fracture modes for different temperatures) under shear and tensile loadings. The damaging mechanisms of the bond under thermomechanical loading have been studied and identified according to microscopic observations on mock-ups which have sustained thermal cycling tests: some cracks appear in the composite, near the bond between the composite and the copper. The correlation between numerical and experimental results have been improved because of the reliability of the composite modelization, the use of residual stresses and the results of the bond mechanical characterisation. (author)

  3. Experimental Tests on the Composite Foam Sandwich Pipes Subjected to Axial Load

    Li, Feng; Zhao, QiLin; Xu, Kang; Zhang, DongDong

    2015-12-01

    Compared to the composite thin-walled tube, the composite foam sandwich pipe has better local flexural rigidity, which can take full advantage of the high strength of composite materials. In this paper, a series of composite foam sandwich pipes with different parameters were designed and manufactured using the prefabricated polyurethane foam core-skin co-curing molding technique with E-glass fabric prepreg. The corresponding axial-load compressive tests were conducted to investigate the influence factors that experimentally determine the axial compressive performances of the tubes. In the tests, the detailed failure process and the corresponding load-displacement characteristics were obtained; the influence rules of the foam core density, surface layer thickness, fiber ply combination and end restraint on the failure modes and ultimate bearing capacity were studied. Results indicated that: (1) the fiber ply combination, surface layer thickness and end restraint have a great influence on the ultimate load bearing capacity; (2) a reasonable fiber ply combination and reliable interfacial adhesion not only optimize the strength but also transform the failure mode from brittle failure to ductile failure, which is vital to the fully utilization of the composite strength of these composite foam sandwich pipes.

  4. Behavior of plywood and fiberglass steel composite tube structures subjected to impact loading

    Armaghani, Seyamend Bilind

    Paratransit buses are custom built as the major vehicle manufacturer produces the custom built passenger cage installed on the chassis for the Paratransit bus. In order for these Paratransit bus members to be sufficient, they have to be evaluated for crashworthiness and energy absorption. This has prompted Florida Department of Transportation (FDOT) to fund research for the safety evaluation of Paratransit busses consisting of crash and safety analysis. There has been a large body of research done on steel subjected to static loads, but more research is needed for steel applied under dynamic loading and high speeds in order to improve crashworthiness in events such as rollovers and side impacts. Bare steel Hollow Structural Section (HSS) tubing are used a lot as structural members of Paratransit buses because of their lightness and progressive buckling under loading. The research will be conducted on quantifying the tubing's behavior under bending by conducting static three point bending and impact loading tests. In addition to the bare tubing, plywood and fiberglass composites are investigated because they are both strong and lightweight and their behavior under dynamic loading hasn't been quantified. As a result, the main purpose of this research is to quantify the differences between the dynamic and static behavior of plywood steel composite and fiberglass steel composite tubing and compare these findings with those of bare steel tubing. The differences will be quantified using detailed and thorough experiments that will examine the composites behavior under both static and dynamic loading. These tests will determine if there are any advantages of using the composite materials and thus allow for recommendations to be made to the FDOT with the goal of improving the safety of Paratransit busses. Tensile tests were conducted to determine the material properties of the tested specimens. Before the static and dynamic experiments are run to investigate the differences

  5. Effects of variations in loading conditions on maximum pressure and muzzle velocity when using composite charge

    V. B. Tawakley

    1960-10-01

    Full Text Available In this paper the effects on maximum pressure and muzzle velocity due to small changes in various quantities defining the loading conditions have been obtained mathematically when using composite charge in guns. Calculations have been done for a particular gun to illustrate these results.

  6. A micromechanical study of porous composites under longitudinal shear and transverse normal loading

    Ashouri Vajari, Danial

    2015-01-01

    The mechanical response of porous unidirectional composites under transverse normal and longitudinal shear loading is studied using the finite element analysis. The 3D model includes discrete and random distribution of fibers and voids. The micromechanical failure mechanisms are taken into accoun...

  7. Effect of organic loading rate and feedstock composition on foaming in manure-based biogas reactors

    Kougias, Panagiotis; Boe, Kanokwan; Angelidaki, Irini

    2013-01-01

    composition, such as content of proteins or lipids were factors that in combination with the organic loading were triggering foaming. More specifically, gelatine could initiate foam formation at a lower OLR than sodium oleate. Moreover, the volume of foam produced by gelatine was relatively stable and was not...... increased when further increasing either OLR or gelatine concentration in the feed. © 2013 Elsevier Ltd....

  8. Effect of Loading Rate on the Behaviour of Partially Pyrolyzed Basalt Fibre Reinforced Composite

    Halasová, Martina; Chlup, Zdeněk; Černý, Martin; Strachota, Adam; Sucharda, Zbyněk; Dlouhý, Ivo

    Montecatini Terme : CIMTEC, 2014. [CIMTEC 2014. Ceramics Congress /13./. 08.06.2014-13.06.2014, Montecatini Terme] R&D Projects: GA ČR GAP107/12/2445 Institutional support: RVO:68081723 ; RVO:67985891 ; RVO:61389013 Keywords : pyrolysis * basalt fibre * impact loading Subject RIV: JI - Composite Materials

  9. Load-induced debonding of FRP composites applied to reinforced concrete

    Blok, Joel; Brown, Jeff

    2009-05-01

    Fiber-reinforced polymer (FRP) composites are widely used to increase the flexural and shear capacity of reinforced concrete (RC) elements. One potential disadvantage is that strengthened surfaces are no longer visible and cracks or delaminations that result from excessive loading or fatigue may go undetected. This research investigated thermal imaging techniques for monitoring and evaluating load-induced delamination of FRP composites applied to small scale RC beams. Two beams (3.5 in x 4.5 in x 58 in) were loaded monotonically to failure. Infrared thermography (IRT) inspections were performed at various load levels through failure using a composite phase imaging technique. Two similar beams were tested in fatigue and periodic IRT inspections were performed at 50,000-cycle intervals. Individual phase values for each pixel were designated as "well-bonded", "suspect" or "unbonded" to indicate the quality of FRP bond. Suspect areas included regions of excess thickened-epoxy tack-coat and smaller installation defects in the unloaded specimens. The long-term objective of this research is to develop a practical framework for conducting quantitative IRT inspections of FRP composites applied to RC and incorporating these results into acceptance criteria for new installations and predictions for the remaining service life of in-service FRP systems. This method may also offer insight into the necessity for repairs to in-service systems.

  10. The relationship of compliance changes during fatigue loading to the fracture of composite materials

    Reifsnider, K. L.; Highsmith, A.

    1982-01-01

    The study outlined here is based on measurements of the change in engineering stiffness values induced by the development of damage in composite laminates during quasi-static or cyclic (fatigue) loading. These changes are found to be related to the individual details of the damage events in the laminates, as well as to the residual strength and life of the laminates. It is believed that the stiffness changes can also be used to relate composite material behavior under cyclic loading to its behavior under quasi-static loading. Results are presented for both notched and unnotched laminates. Compliance changes are found to be caused by damage events that bring about both global and local redistributions of stress. It is also found that the redistributions of stress determine the residual strength of the laminate. The quantitative link between compliance changes and fracture strength is the mechanics of the internal stress redistributions.

  11. Reliability Analysis for Adhesive Bonded Composite Stepped Lap Joints Loaded in Fatigue

    Kimiaeifar, Amin; Sørensen, John Dalsgaard; Lund, Erik;

    2012-01-01

    This paper describes a probabilistic approach to calculate the reliability of adhesive bonded composite stepped lap joints loaded in fatigue using three- dimensional finite element analysis (FEA). A method for progressive damage modelling is used to assess fatigue damage accumulation and residual...... strength under fully reversed cyclic loading based on stiffness/strength degradation. The FEA simulations are conducted using the commercial FEA code ANSYS 12.1. A design equation for fatigue failure of wind turbine blades is chosen based on recommendations given in the wind turbine standard IEC 61400...... by the wind turbine standard IEC 61400-1. Finally, an approach for the assessment of the reliability of adhesive bonded composite stepped lap joints loaded in fatigue is presented. The introduced methodology can be applied in the same way to calculate the reliability level of wind turbine blade...

  12. Discrete Meso-Element Simulation of Failure Behavior of Short-Fiber Composites under Shock Loading

    Tang, Z. P.; Liu, Wenyan; Liu, Yunxin

    1999-06-01

    Recent years, it was paid more attention to better understanding the failure behavior and mechanism of heterogeneous materials at meso- scale level. In this paper, the crack initiation and development in epoxy composite reinforced with short steel fibre under dynamic loading were simulated and analyzed with 2D Discrete Meso-Element Dynamic Method. Results show that cracks initiate at the tips of fibres on the Loading side where stress concentrates. The effective strength of the composite sample is related to shape, orientation, weight percentage of the fibres, and particularly, the bonding strength between fibre and matrix. In the case of low bonding strength, the crack will propagate along the fibre and finally penetrate the whole sample. The differences compared with static loading are also discussed.

  13. Testing and Analysis of Composite Skin/Stringer Debonding Under Multi-Axial Loading

    Krueger, Ronald; Cvitkovich, Michael K.; O'Brien, T. Kevin; Minguet, Pierre J.

    2000-01-01

    A consistent step-wise approach is presented to investigate the damage mechanism in composite bonded skin/stringer constructions under uniaxial and biaxial (in-plane/out-of-plane) loading conditions. The approach uses experiments to detect the failure mechanism, computational stress analysis to determine the location of first matrix cracking and computational fracture mechanics to investigate the potential for delamination growth. In a first step, tests were performed on specimens, which consisted of a tapered composite flange, representing a stringer or frame, bonded onto a composite skin. Tests were performed under monotonic loading conditions in tension, three-point bending, and combined tension/bending to evaluate the debonding mechanisms between the skin and the bonded stringer. For combined tension/bending testing, a unique servohydraulic load frame was used that was capable of applying both in-plane tension and out-of-plane bending loads simultaneously. Specimen edges were examined on the microscope to document the damage occurrence and to identify typical damage patterns. For all three load cases, observed failure initiated in the flange, near the flange tip, causing the flange to almost fully debond from skin. In a second step, a two dimensional plane-strain finite element model was developed to analyze the different test cases using a geometrically nonlinear solution. For all three loading conditions, computed principal stresses exceeded the transverse strength of the material in those areas of the flange where the matrix cracks had developed during the tests. In a third step, delaminations of various lengths were simulated in two locations where delaminations were observed during the tests. The analyses showed that at the loads corresponding to matrix ply crack initiation computed strain energy release rates exceeded the values obtained from a mixed mode failure criterion in one location, Hence. Unstable delamination propagation is likely to occur as

  14. Enhanced microwave shielding and mechanical properties of high loading MWCNT–epoxy composites

    Dispersion of high loading of carbon nanotubes (CNTs) in epoxy resin is a challenging task for the development of efficient and thin electromagnetic interference (EMI) shielding materials. Up to 20 wt% of multiwalled carbon nanotubes (MWCNTs) loading in the composite was achieved by forming CNT prepreg in the epoxy resin as a first step. These prepreg laminates were then compression molded to form composites which resulted in EMI shielding effectiveness of −19 dB for 0.35 mm thick film and −60 dB at for 1.75 mm thick composites in the X-band (8.2–12.4 GHz). One of the reasons for such high shielding is attributed to the high electrical conductivity of the order of 9 S cm−1 achieved in these composites which is at least an order of magnitude higher than previously reported results at this loading. In addition, an improvement of 40 % in the tensile strength over the neat resin value is observed. Thermal conductivity of the MWCNTs–epoxy composite reached 2.18 W/mK as compared to only 0.14 W/mK for cured epoxy.

  15. Relationship between the Composition of Polymer of n-Alkyl Substituted Acrylate and Vinyl Amine and Their Performance on Pour Point Depression

    Jiang Qingzhe; Luo Fangmin; Song Zhaozheng; Ke Ming

    2005-01-01

    Polymer of n-alkyl substituted acrylate (PA) with the alkyl side chains C16- 30 were synthesized.Their crystallinity, solubility and effect on pour point depression were studied. Results showed that only carbon atoms located far away from polar groups of PA pour point depressants participated in crystallization.When the number of carbon atoms that participated in crystallization is about three fourths of the average carbon number of wax in crude, the effect of PA is the best. The molecular weight distribution of PA pour point depressant has little influence on the effect of pour point depression, and the average molecular weight of PA in the range of (1.5- 2.2)× 104 shows the best effect. The introduction of polar groups into the molecule of PA can improve its performance. However, a too high content of polar groups in PA would cause deterioration, and even lead to loss of PA's performance for pour point depression.

  16. Failure modes of vacuum plasma spray tungsten coating created on carbon fibre composites under thermal loads

    Vacuum plasma spray tungsten (VPS-W) coating created on a carbon fibre reinforced composite (CFC) was tested under two thermal load schemes in the electron beam facility to examine the operation limits and failure modes. In cyclic ELM-like short transient thermal loads, the VPS-W coating was destroyed sub-layer by sub-layer at 0.33 GW/m2 for 1 ms pulse duration. At longer single pulses, simulating steady-state thermal loads, the coating was destroyed at surface temperatures above 2700 deg. C by melting of the rhenium containing multilayer at the interface between VPS-W and CFC. The operation limits and failure modes of the VPS-W coating in the thermal load schemes are discussed in detail.

  17. Micromechanical Analysis of FRP Composite with Orthotropic Fibers Subjected To Longitudinal and Transverse Loading

    M. Gowtha Muneswara Rao

    2014-05-01

    Full Text Available The present research work deals with the micromechanical analysis of fiber reinforced composites with orthotropic fibers under fiber directional tensile loading and transverse directional tensile loading using three-dimensional finite element method. The problem is modeled in ANSYS software and the FE model is validated with bench mark results. Longitudinal Young's modulus and transverse Young's modulus corresponding Poisson's ratios are predicted. Fiber reinforced composite materials are now an important class of an engineering materials. They offer outstanding mechanical properties, unique flexibility in design capabilities, and ease of fabrication. Additional advantages include light weight and corrosion resistance, impact resistance, and excellent fatigue strength. Today fiber composites are routinely used in such diverse applications as automobiles, aircraft, space vehicles, offshore structures, containers and piping, sporting goods, electronics, and appliances.

  18. Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

    吴玉程; 吴侠; 李广海; 张立德

    2003-01-01

    In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica,the silica was prepared by sol-gel technique,leading to an amorphous solid with mesoporosity,and the pore size distribution is narrow,centered at 3-5 nm.The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen.The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination,resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature.The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

  19. Prediction of Spring Rate and Initial Failure Load due to Material Properties of Composite Leaf Spring

    Oh, Sung Ha [Maxoft Inc., Seongnam (Korea, Republic of); Choi, Bok Lok [Gangneung-Wonju National University, Gangneung (Korea, Republic of)

    2014-12-15

    This paper presented analysis methods for adapting E-glass fiber/epoxy composite (GFRP) materials to an automotive leaf spring. It focused on the static behaviors of the leaf spring due to the material composition and its fiber orientation. The material properties of the GFRP composite were directly measured based on the ASTM standard test. A reverse implementation was performed to obtain the complete set of in-situ fiber and matrix properties from the ply test results. Next, the spring rates of the composite leaf spring were examined according to the variation of material parameters such as the fiber angles and resin contents of the composite material. Finally, progressive failure analysis was conducted to identify the initial failure load by means of an elastic stress analysis and specific damage criteria. As a result, it was found that damage first occurred along the edge of the leaf spring owing to the shear stresses.

  20. Prediction of Spring Rate and Initial Failure Load due to Material Properties of Composite Leaf Spring

    This paper presented analysis methods for adapting E-glass fiber/epoxy composite (GFRP) materials to an automotive leaf spring. It focused on the static behaviors of the leaf spring due to the material composition and its fiber orientation. The material properties of the GFRP composite were directly measured based on the ASTM standard test. A reverse implementation was performed to obtain the complete set of in-situ fiber and matrix properties from the ply test results. Next, the spring rates of the composite leaf spring were examined according to the variation of material parameters such as the fiber angles and resin contents of the composite material. Finally, progressive failure analysis was conducted to identify the initial failure load by means of an elastic stress analysis and specific damage criteria. As a result, it was found that damage first occurred along the edge of the leaf spring owing to the shear stresses

  1. Loading-dependent elemental composition of α-pinene SOA particles

    J. L. Jimenez

    2008-08-01

    Full Text Available The chemical composition of secondary organic aerosol (SOA particles, formed by the dark ozonolysis of α-pinene, was characterized by a high-resolution time-of-flight aerosol mass spectrometer. The experiments were conducted using a continuous-flow chamber, allowing the particle mass loading and chemical composition to be maintained for several days. The organic portion of the particle mass loading was varied from 0.5 to >140 μg/m3 by adjusting the concentration of reacted α-pinene from 0.9 to 91.1 ppbv. The mass spectra of the organic material changed with loading. For loadings below 5 μg/m3 the unit-mass-resolution m/z 44 signal intensity exceeded that of m/z 43, suggesting more oxygenated organic material at lower loadings. Composition measurements displayed a greater dependence for lower loadings (0.5 to 15 μg/m3 compared to higher loadings (15 to >140 μg/m3. The high-resolution mass spectra showed that from >140 to 0.5 μg/m3 the mass percentage of fragments containing carbon and oxygen (CxHyOz+ monotonically increased from 48% to 54%. Correspondingly, the mass percentage of fragments representing CxHy+ decreased from 52% to 46%, and the atomic oxygen-to-carbon ratio increased from 0.29 to 0.45. The atomic ratios were accurately parameterized by a four-product basis set of decadal volatility (viz. 0.1, 1.0, 10, 100 μg/m−3 employing products with the empirical formulas C1H1.32O0.48, C1H1.36O0.39, C1H1.57O0.24, and C1H1.76O0.14. These findings suggest considerable caution is warranted in the extrapolation of laboratory results that were obtained under conditions of relatively high loading (i.e., >15 μg/m3 to modeling applications relevant to the atmosphere, for which loadings of 0.1 to 20 μg/m3 are typical. For the lowest loadings, the particle mass spectra resembled observations reported in the literature for some atmospheric particles.

  2. Modelling of Fiber/Matrix Debonding of Composites Under Cyclic Loading

    Naghipour, Paria; Pineda, Evan J.; Bednarcyk, Brett A.; Arnold, Steven M.

    2013-01-01

    The micromechanics theory, generalized method of cells (GMC), was employed to simulate the debonding of fiber/matrix interfaces, within a repeating unit cell subjected to global, cyclic loading, utilizing a cyclic crack growth law. Cycle dependent, interfacial debonding was implemented as a new module to the available GMC formulation. The degradation of interfacial stresses, with applied load cycles, was achieved via progressive evolution of the interfacial compliance. A periodic repeating unit cell, representing the fiber/matrix architecture of a composite, was subjected to combined normal and shear loadings, and degradation of the global transverse stress in successive cycles was monitored. The obtained results were compared to values from a corresponding finite element model. Reasonable agreement was achieved for combined normal and shear loading conditions, with minimal variation for pure loading cases. The local effects of interfacial debonding, and fatigue damage will later be combined as sub-models to predict the experimentally obtained fatigue life of Ti-15-3/Sic composites at the laminate level.

  3. Regularity of acoustic radiation at ascending load on a pair of friction from a composite material

    С. Ф. Філоненко

    2013-07-01

    Full Text Available In this article the simulation the results of acoustic emission signals formed by friction surfaces with composite materials at load increasing were showed. The results showed that at increase of axial load increases the amplitude of the resulting parameters of acoustic emission signals, such as the average amplitude, its standard deviation and variance. Thus were obtained the basic changes of amplitude parameters generated signals. Was determined that the variation of the percentage increase in the average amplitude, its standard deviation and variance were  the same type of character, with well approximate by linear functions. The results showed that with growing of axial load the percent increase in average amplitude of the resulting acoustic emission signals. Also, an analysis of the energy parameters of acoustic emission with increasing axial load on the friction pair with composite materials was conducted. The simulation results showed that the percentage increase in the average level of energy and its standard deviation are approximate by linear functions. At the same time the greatest percentage increase with increasing axial load on the friction pair is observed in the dispersion of the average energy of the resulting acoustic emission signals. The results showed that at experimental study of the acoustic emission signals with increasing axial load on the friction pair with composite materials greatest growth is expected in the average amplitude of the resulting AE signals. The growth of its standard deviation and variance will be not significant. At the same time, the greatest growth is expected in the dispersion of the average energy of acoustic emission signals

  4. Dynamic delamination in curved composite laminates under quasi-static loading

    In the wind energy industry, new advances in composite manufacturing technology and high demand for lightweight structures are fostering the use of composite laminates in a wide variety of shapes as primary load carrying elements. However, once a moderately thick laminate takes highly curved shape, such as an L-shape, Interlaminar Normal Stresses (ILNS) are induced together with typical Interlaminar Shear Stresses (ILSS) on the interfaces between the laminas. The development of ILNS promotes mode-I type of delamination propagation in the curved part of the L-shaped structure, which is a problem that has recently raised to the forefront in in-service new composite wind turbines. Delamination propagation in L-shaped laminates can be highly dynamic even though the loading is quasistatic. An experimental study to investigate dynamic delamination under quasi-static loading is carried out using a million fps high speed camera. Simulations of the experiments are conducted with a bilinear cohesive zone model implemented in user subroutine of the commercial FEA code ABAQUS/explicit. The experiments were conducted on a 12-layered woven L-shaped CFRP laminates subjected to shear loading perpendicular to the arm of the specimen with a free-sliding fixture to match the boundary conditions used in the FEA. A single delamination is found to initiate at the 5th interface during a single drop in the load. The delamination is then observed to propagate to the arms at intersonic speed of 2200m/s. The results obtained using cohesive zone models in the numerical simulations were found to be in good agreement with experimental results in terms of load displacement behavior and delamination history

  5. Controlled release of anti-diabetic drug Gliclazide from poly(caprolactone)/poly(acrylic acid) hydrogels.

    Bajpai, S K; Chand, Navin; Soni, Shweta

    2015-01-01

    Drug Gliclazide (Glz) has limited solubility and low bioavailability. In order to obtain a controlled release of this drug and to improve its bioavailability, the drug has been loaded into poly(caprolactone) (PCL)/poly(acrylic acid) (PAAc) hydrogels, prepared by free radical polymerization of acrylic acid in the presence of poly(caprolactone) in acetone medium using azo-isobutyronitrile as initiator and N,N' methylene bisacrylamide as cross-linking agent. The swelling behaviour of these hydrogels has been investigated in the physiological gastric and intestinal fluids to obtain an optimum composition suitable for delivery of a biologically active compound. The gels were loaded with anti-diabetic drug Glz and a detailed investigation of release of drug has been carried out. Various kinetic models have been applied on the release data. Finally, the Albino wistar rats were treated for Streptozotocin plus nicotinamide - induced diabetes using a Glz-loaded PCL/PAAc hydrogel. The results indicated a fair reduction in the glucose level of rats. PMID:26135033

  6. Stress Analysis of Laminated Composite Cylinders Under Non-Axisymmetric Loading

    Starbuck, J.M.

    1999-10-26

    The use of thick-walled composite cylinders in structural applications has seen tremendous growth over the last decade. Applications include pressure vessels, flywheels, drive shafts, spoolable tubing, and production risers. In these applications, the geometry of a composite cylinder is axisymmetric but in many cases the applied loads are non-axisymmetric and more rigorous analytical tools are required for an accurate stress analysis. A closed-form solution is presented for determining the layer-by-layer stresses, strains, and displacements and first-ply failure in laminated composite cylinders subjected to non-axisymmetric loads. The applied loads include internal and external pressure, axial force, torque, axial bending moment, uniform temperature change, rotational velocity, and interference fits. The formulation is based on the theory of anisotropic elasticity and a state of generalized plane deformation along the axis of the composite cylinder. Parametric design trade studies can be easily and quickly computed using this closed-form solution. A computer program that was developed for performing the numerical calculations is described and results from specific case studies are presented.

  7. Dynamic stability of simply supported composite cylindrical shells under partial axial loading

    Dey, Tanish; Ramachandra, L. S.

    2015-09-01

    The parametric vibration of a simply supported composite circular cylindrical shell under periodic partial edge loadings is discussed in this article. Donnell's nonlinear shallow shell theory considering first order shear deformation theory is used to model the shell. The applied partial edge loading is represented in terms of a Fourier series and stress distributions within the cylindrical shell are determined by prebuckling analysis. The governing equations of the dynamic instability of shells are derived in terms of displacements (u-v-w) and rotations (φx, φθ). Employing the Galerkin and Bolotin methods the dynamic instability regions are computed. Using the expression for the stress function derived in this paper, the pre-buckling stresses in the cylindrical shell due to partial loading can be calculated explicitly. Numerical results are presented to show the influence of radius-to-thickness ratio, different partial edge loading distributions and shear deformation on the dynamic instability regions. The linear and nonlinear responses in the stable and unstable regions are presented to bring out the characteristic features of the dynamic instability regions, such as the existence of beats, its dependence on forcing frequency and effect of nonlinearity on the response. The effect of dynamic load amplitude on the nonlinear response is also studied. It is found that for higher values of dynamic loading, the shell exhibits chaotic behavior.

  8. Monotonic and fatigue properties of kenaf /glass hybrid composites under fully reversed cyclic loading

    Sharba, M. J.; Leman, Z.; Sultan, M. T. H.; Ishak, M. R.; Hanim, M. A. A.

    2015-12-01

    The aim of this work is to investigate the effect of hybridization of kenaf-glass fibers reinforced unsaturated polyester on fatigue life. Three types of composites were fabricated using hands lay-up method, namely, kenaf, glass, and hybrid composites with 30% of weight fraction, the hybrid was mixed with a ratio of kenaf: glass 10:20. Monotonic tests were achieved (Tensile and compression) to determine the fatigue stress levels. Fully reversed fatigue loading was conducted with a stress ratio of -1 and stress levels 55-85% of the ultimate static stresses, all tests were conducted at 10 Hz of frequency. The results proof a positive hybrid composite; also agree with the rule of mixture that can predict the final composite properties. Moreover, it's been observed an improvement in overall mechanical properties of hybrid compared to individual ones.

  9. Conductivity of microfibrillar polymer-polymer composites with CNT-loaded microfibrils or compatibilizer: A comparative study

    Fakirov, S.; S. M. Panamoottil; P. Potschke; R. J. T. Lin; Bhattacharyya, D

    2013-01-01

    Conductive polymer composites have wide ranging applications, but when they are produced by conventional melt blending, high conductive filler loadings are normally required, hindering their processability and reducing mechanical properties. In this study, two types of polymer-polymer composites were studied: i) microfibrillar composites (MFC) of polypropylene (PP) and 5 wt% carbon nanotube (CNT) loaded poly(butylene terephthalate) (PBT) as reinforcement, and ii) maleic anhydride-grafted poly...

  10. Impact damage evolution under fatigue loading by InfraRed Thermography on composite structures

    Pastor M.-L.

    2010-06-01

    Full Text Available This study deals with cumulative damage and its evolution in already impact damage composite structure. In order to follow the growing damage and to compare it with cumulative model, tests are monitored with an InfraRed thermography system. A carbon-epoxy composite is first low-energy impacted and then fatigued under tensioncompression loading. This study also enables a very fast analysis of predicting the damage evolution coupling InfraRed Thermography as NDT method and InfraRed thermography as a following system.

  11. Interface debond crack growth in tension–tension cyclic loading of single fiber polymer composites

    Pupurs, Andrejs; Goutianos, Stergios; Brøndsted, Povl;

    2013-01-01

    Fiber/matrix interface debond crack growth from a fiber break is defined as one of the key mechanisms of fatigue damage in unidirectional composites. Considering debond as an interface crack its growth in cyclic loading is analyzed utilizing a power law, where the debond growth rate is a power...... glass fiber/epoxy single fiber composites. Analytical method in the steady-state growth region and FEM for short debonds are combined for calculating the strain energy release rate of the growing debond crack. Interface failure parameters in fatigue are determined by fitting the modeling and...

  12. Meshless Analysis of Laminated Composite and Sandwich Plates Subjected to Various Types of Loads

    Singh, Jeeoot; Singh, Sandeep; Shukla, K. K.

    2014-03-01

    The bending analysis of laminated composite and sandwich plates using different radial basis functions and higher-order shear deformation theory is presented. This meshfree technique is insensitive to spatial dimension and considers only a cloud of nodes (centers) for the spatial discretization of both the problem domain and the boundary. Numerical results for simply supported isotropic, symmetric cross-ply composite and sandwich plate are presented. The results are compared with other available results. It is observed that convergence of the polynomial function is faster as compared to other radial basis functions, whereas Gaussian function takes the least solution time. The effect of various types of loadings on sandwich plate is presented.

  13. [Acrylic resin removable partial dentures

    Baat, C. de; Witter, D.J.; Creugers, N.H.J.

    2011-01-01

    An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of

  14. Optimization of coating diameter of fiber optic sensors embedded in composite structures under arbitrary loading conditions

    Lammens, Nicolas; Luyckx, Geert; Voet, Eli; van Paepegem, Wim; Degrieck, Joris

    2015-11-01

    Due to mismatches in size and material properties, optical fiber (OF) sensors act as inclusions when embedded in composite hosts. The resulting stress concentrations surrounding the OF sensor may lead to premature failure of the host structure. In this work, a novel technique is presented to determine optimal coating properties for OF sensors embedded in composite structures in order to minimize stress concentrations surrounding these sensors. The method is validated against methodologies available in literature and is shown to produce identical results under these specific circumstances. Compared to the methods in literature, the proposed method is significantly more flexible as it allows the optimization of the coating for any arbitrary load condition. The results of the computations can be reused for any load case in the given combination of host and coating material, reducing the computations to a one time effort for a specific combination of host and coating.

  15. Timber-Concrete Composite Floor Beams under 4 Years Long-Term Load

    David Yeoh

    2013-12-01

    Full Text Available The long-term behaviour of timber-concrete composite is characterized by the response of its three components (timber, concrete and connection to load, moisture content, temperature and relative humidity of the environment. This paper reports results of a 4-years long-term test on three 8m span laminated veneer lumber (LVL-concrete composite floor beams under service load performed in an indoor, uncontrolled, and unheated environment at the University of Canterbury. The environmental conditions were characterized by either low temperature with high relative humidity or high temperature with low relative humidity, conditions considered to be reasonably severe and presumably close to service class 3 according to Eurocode 5. The mid-span deflections were extrapolated to the end of service life (50 years and compared to span/200 deflection limit, which was exceeded by all beams.

  16. Optimum Design of Composite Sandwich Structures Subjected to Combined Torsion and Bending Loads

    Li, Xiang; Li, Gangyan; Wang, Chun H.; You, Min

    2012-06-01

    This research is motivated by the increase use of composite sandwich structures in a wide range of industries such as automotive, aerospace and civil infrastructure. To maximise stiffness at minimum weight, the paper develops a minimum weight optimization method for sandwich structure under combined torsion and bending loads. We first extend the minimum-weight design of sandwich structures under bending load to the case of torsional deformation and then present optimum solutions for the combined requirements of both bending and torsional stiffness. Three design cases are identified for a sandwich structure required to meet multiple design constraints of torsion and bending stiffness. The optimum solutions for all three cases are derived. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins.

  17. The Use of Micro and Nano Particulate Fillers to Modify the Mechanical and Material Properties of Acrylic Bone Cement

    Slane, Joshua A.

    Acrylic bone cement (polymethyl methacrylate) is widely used in total joint replacements to provide long-term fixation of implants. In essence, bone cement acts as a grout by filling in the voids left between the implant and the patient's bone, forming a mechanical interlock. While bone cement is considered the `gold standard' for implant fixation, issues such as mechanical failure of the cement mantle (aseptic loosening) and the development of prosthetic joint infection (PJI) still plague joint replacement procedures and often necessitate revision arthroplasty. In an effort to address these failures, various modifications are commonly made to bone cement such as mechanical reinforcement with particles/fibers and the addition of antibiotics to mitigate PJI. Despite these attempts, issues such as poor particle interfacial adhesion, inadequate drug release, and the development of multidrug resistant bacteria limit the effectiveness of bone cement modifications. Therefore, the overall goal of this work was to use micro and nanoparticles to enhance the properties of acrylic bone cement, with particular emphasis placed on improving the mechanical properties, cumulative antibiotic release, and antimicrobial properties. An acrylic bone cement (Palacos R) was modified with three types of particles in various loading ratios: mesoporous silica nanoparticles (for mechanical reinforcement), xylitol microparticles (for increased antibiotic release), and silver nanoparticles (as an antimicrobial agent). These particles were used as sole modifications, not in tandem with one another. The resulting cement composites were characterized using a variety of mechanical (macro to nano, fatigue, fracture, and dynamic), imaging, chemical, thermal, biological, and antimicrobial testing techniques. The primary outcomes of this dissertation demonstrate that: (1) mesoporous silica, as used in this work, is a poor reinforcement phase for acrylic bone cement, (2) xylitol can significantly

  18. Damage and failure behavior of metal matrix composites under biaxial loads

    Kirkpatrick, Steven Wayne

    Metal matrix composites (MMCs) are being considered for increased use in structures that require the ductility and damage tolerance of the metal matrix and the enhanced strength and creep resistance at elevated temperatures of high performance fibers. Particularly promising for advanced aerospace engines and airframes are SiC fiber/titanium matrix composites (TMCs). A large program was undertaken in the Air Force to characterize the deformation and failure behaviors of TMCs and to develop computational models that can be used for component design. The effort reported here focused on a SiC SCS-6/Timetal 21S composite under biaxial loading conditions. Biaxial loading conditions are important because multiaxial stresses have been shown to influence the strength and ductility of engineering materials and, in general, structural components are subjected to multiaxial loads. The TMC material response, including stress-strain curves and failure surfaces, was measured using a combination of off-axis uniaxial tension and compression tests and biaxial cruciform tests. The off-axis tests produce combinations of in-plane tension, compression, and shear stresses, the mix of which are controlled by the relative angle between the fiber and specimen axes. The biaxial cruciform tests allowed independent control over the tensile or compressive loads in the fiber and transverse directions. The results of these characterization tests were used to develop a microstructural constitutive model and failure criteria. The basis of the micromechanical constitutive model is a representative unit volume of the MMC with a periodic array of fibers. The representative unit volume is divided into a fiber and three matrix cells for which the microstructural equilibrium and compatibility equations can be analyzed. The resulting constitutive model and associated failure criteria can be used to predict the material behavior under general loading conditions.

  19. Investigation and characterization of constraint effects on flaw growth during fatigue loading of composite materials

    Stinchcomb, W. W.; Reifsnider, K. L.; Yeung, P.; Gibbins, M. N.

    1979-01-01

    An investigative program is presented in an attempt to add to the current understanding of constraint effects on the response of composite materials under cyclic loading. The objectives were: (1) to use existing data and to develop additional data in order to establish an understanding and quantitative description of flaw growth in unidirectional lamina under cyclic loading at different load direction to fiber direction angles; (2) to establish a similar understanding and description of flaw growth in lamina which are embedded in laminates between other unflawed lamina; (3) to determine the nature of the influence of constraint on flaw growth by quantitatively comparing the results of the tests; and (4) to develop a model and philosophy of constraints effects based on our investigative results.

  20. Structural effects of three-dimensional angle-interlock woven composite undergoing bending cyclic loading

    Jin, LiMin; Yao, Yao; Yu, YiMin; Rotich, Gideon; Sun, BaoZhong; Gu, BoHong

    2014-03-01

    This paper reports the structural effects of three-dimensional (3-D) angle-interlock woven composite (3DAWC) undergoing three-point bending cyclic loading from experimental and finite element analysis (FEA) approaches. In experiment, the fatigue tests were conducted to measure the bending deflection and to observe the damage morphologies. By the FEA approach, a micro-structural unit-cell model of the 3DAWC was established at the yarn level to simulate the fatigue damage. The stress degradation at the loading condition of constant deformation amplitude was calculated to show the degradation of mechanical properties. In addition, the stress distribution, fatigue damage evolution and critical damage regions were also obtained to qualitatively reveal the structural effects and damage mechanisms of the 3DAWC subjected to three-point bending cyclic loading.

  1. Characterization of debond growth mechanism in adhesively bonded composites under mode II static and fatigue loadings

    Mall, S.; Kochhar, N. K.

    1988-01-01

    An experimental investigation of adhesively bonded composite joint was conducted to characterize the debond growth mechanism under mode II static and fatigue loadings. For this purpose, end-notched flexure specimens of graphite/epoxy (T300/5208) adherends bonded with EC 3445 adhesive were tested. In all specimen tested, the fatigue failure occurred in the form of cyclic debonding. The present study confirmed the result of previous studies that total strain-energy-release rate is the driving parameter for cyclic debonding. Further, the debond growth resistance under cyclic loading with full shear reversal (i.e., stress ratio, R = -1) is drastically reduced in comparison to the case when subjected to cyclic shear loading with no shear reversal (i.e., R = 0.1).

  2. Design optimization of blade stiffened laminated composite plates for maximum buckling load

    Achenbach, Mark R.

    1990-01-01

    Approved for public release; distribution unlimited. The buckling load of a blade stiffened laminated composite plate having midplane symmetry is maximized for a given total weight. The thickness of the layers and the width and height of the stiffener are taken as the design variables. Buckling analysis is carried out using a finite element method. The optimization problem is solved using commercially available optimization packages. Due to the highly nonlinear nature of the optimality equ...

  3. Failure Test and Finite Element Simulation of a Large Wind Turbine Composite Blade under Static Loading

    Xiao Chen; Wei Zhao; Xiao Lu Zhao; Jian Zhong Xu

    2014-01-01

    This study presented a failure analysis of a 52.3 m composite wind turbine blade under static loading. Complex failure characteristics exhibited at the transition region of the blade were thoroughly examined and typical failure modes were indentified. In order to predict multiple failure modes observed in the tests and gain more insights into the failure mechanisms of the blade, a Finite Element (FE) simulation was performed using a global-local modeling approach and Progressive Failure Anal...

  4. Impact of Hygrothermal and Loading Conditions on Apparent Diffusivity of GFRP Composites

    Singh, Sushma; Khushmeet KUMAR

    2014-01-01

    Glass fibre-reinforced polymer (GFRP) has been used as an alternative to steel in concrete due to high strength-to-weight ratio, high stiffness-to-weight ratio, and corrosion and fatigue resistance. The main environmental factors for the deterioration of GFRP sandwich composites are temperature, sunshine, water/moisture, alkalinity and load. Most of the early durability tests were carried out with reference to application of FRP (Fibre Reinforced Polymer) in aerospace industries. Hygrothermal...

  5. Lifetime predictions of polymer matrix composites under constant or monotonic load

    Guedes, RM

    2006-01-01

    A revision of long-term lifetime prediction of composite materials under constant and monotonic load is presented. The main failure criteria revised are energy-based criteria and fracture mechanics. It is shown that they all predict a similar relation between constant stress and constant stress rate failure strength. It is also demonstrated that the methodology proposed by Miyano et al., based on linear damage accumulation law (LCD), produces similar results. Experimental cases published in l...

  6. Advances in Stability of Composite Airframe Structures Regarding Collapse, Robust Design and Dynamic Loading

    Degenhardt, Richard

    2008-01-01

    European aircraft industry demands for reduced development and operating costs, by 20% and 50% in the short and long term, respectively. Structural weight reduction by exploitation of structural reserves in composite aerospace structures contributes to this aim, however, it requires accurate and experimentally validated stability analysis of real structures under realistic loading conditions. This paper presents new achievements from the area of computational and experimental stability resear...

  7. Postbuckling Behaviour of Anisotropic Laminated Composite Plates due to Shear Loading

    V. Balamurugan

    1998-10-01

    Full Text Available This study investigates postbuckling behaviour of laminated composite plates using a nine-noded shear flexible quadrilateral plate element. The formulation includes nonlinear strain-displacement relation based on von Karman's assumption. The nonlinear governing equations are solved through iteration. A detailed parametric study is carried out to bring out the influence of ply-angle, aspect ratio and material properties on the postbuckling strength of laminates due to in-plane shear loads.

  8. Effect of Molecular Weight on Load Transfer in Nanotube / Polymer Composites

    Mu, Minfang; Du, Fangming; Haggenmueller, Reto; Winey, Karen

    2006-03-01

    The tensile moduli of nanocomposite fibers are being investigated with attention to the molecular weight of the polymer. Nanocomposites composed of single wall carbon nanotube (SWNT) and poly(methyl methacrylate) (PMMA) were prepared by our coagulation method and processed into composite fibers using melt fiber spinning. SWNT in the fibers are aligned and the nanotube - nanotube interactions are diminished, so that, the mechanical load on SWNT is mainly from polymer - SWNT interactions. The tensile moduli along the direction parallel to the SWNT were characterized at 1.0 mm / sec with the fiber length of 25.4 mm. At a weight-average molecular weight (Mw) 25 kDa, the tensile moduli of PMMA are the same with the composites. However, when the Mw is increased to 100kDa, the tensile moduli are improved greatly by adding SWNT. This indicates that the load in the composites is transferred to the SWNT more efficiently at 100 kDa molecular weight. A micromechanics model was used to relate the elastic shear stress on the polymer - SWNT interface to the polymer chain length. It showed that with increasing polymer chain length, the interfacial shear stress was enhanced. This study demonstrates the importance of the molecular weight of the polymer matrix to the load transfer in nanocomposites.

  9. Doxorubicin-loaded mesoporous silica nanoparticle composite nanofibers for long-term adjustments of tumor apoptosis

    Yuan, Ziming; Pan, Yue; Cheng, Ruoyu; Sheng, Lulu; Wu, Wei; Pan, Guoqing; Feng, Qiming; Cui, Wenguo

    2016-06-01

    There is a high local recurrence (LR) rate in breast-conserving therapy (BCT) and enhancement of the local treatment is promising as a way to improve this. Thus we propose a drug delivery system using doxorubicin (DOX)-loaded mesoporous silica nanoparticle composite nanofibers which can release anti-tumor drugs in two phases—burst release in the early stage and sustained release at a later stage—to reduce the LR of BCT. In the present study, we designed a novel composite nanofibrous scaffold to realize the efficient release of drugs by loading both DOX and DOX-loaded mesoporous silica nanoparticles into an electrospun PLLA nanofibrous scaffold. In vitro results demonstrated that this kind of nanomaterial can release DOX in two phases, and the results of in vivo experiments showed that this hybrid nanomaterial significantly inhibited the tumor growth in a solid tumor model. Histopathological examination demonstrated that the apoptosis of tumor cells in the treated group over a 10 week period was significant. The anti-cancer effects were also accompanied with decreased expression of Bcl-2 and TNF-α, along with up-regulation of Bax, Fas and the activation of caspase-3 levels. The present study illustrates that the mesoporous silica nanoparticle composite nanofibrous scaffold could have anti-tumor properties and could be further developed as adjuvant therapeutic protocols for the treatment of cancer.

  10. Finite Element Analysis of Composite Hardened Walls Subjected to Blast Loads

    Girum S. Urgessa

    2009-01-01

    Full Text Available Problem statement: There is currently no standard design guideline to determine the number of composites needed to retrofit masonry walls in order to withstand a given explosion. Past design approaches were mainly based on simplified single-degree-of-freedom analysis. A finite element analysis was conducted for concrete masonry walls hardened with composites and subjected to short duration blast loads. Approach: The analysis focused on displacement time history responses which form the basis for retrofit design guidelines against blast loadings. The blast was determined from 0.5 kg equivalent TNT explosive at 1.83 m stand-off distance to simulate small mailroom bombs. Two and four layered retrofitted walls were investigated. Uncertainties in the finite model analysis of walls such as pressure distributions, effect of mid height explosive bursts versus near the ground explosive bursts and variations in modulus of elasticity of the wall were presented. Results: Uniformly distributed blast loads over the retrofitted wall height produced a small difference in peak displacement results when compared to the non-uniform pressure distribution. Ground explosive burst was shown to produce a 62.7% increase in energy and a higher peak displacement response when compared to mid-height explosive burst. Conclusion: The parametric study on the variation of modulus of elasticity of concrete masonry showed no significant effect on peak displacement affirming the use of the resistance deflection contribution of the composite in retrofit designs.

  11. Damage Tolerance of Pre-Stressed Composite Panels Under Impact Loads

    Johnson, Alastair F.; Toso-Pentecôte, Nathalie; Schueler, Dominik

    2014-02-01

    An experimental test campaign studied the structural integrity of carbon fibre/epoxy panels preloaded in tension or compression then subjected to gas gun impact tests causing significant damage. The test programme used representative composite aircraft fuselage panels composed of aerospace carbon fibre toughened epoxy prepreg laminates. Preload levels in tension were representative of design limit loads for fuselage panels of this size, and maximum compression preloads were in the post-buckle region. Two main impact scenarios were considered: notch damage from a 12 mm steel cube projectile, at velocities in the range 93-136 m/s; blunt impact damage from 25 mm diameter glass balls, at velocities 64-86 m/s. The combined influence of preload and impact damage on panel residual strengths was measured and results analysed in the context of damage tolerance requirements for composite aircraft panels. The tests showed structural integrity well above design limit loads for composite panels preloaded in tension and compression with visible notch impact damage from hard body impact tests. However, blunt impact tests on buckled compression loaded panels caused large delamination damage regions which lowered plate bending stiffness and reduced significantly compression strengths in buckling.

  12. Simulation of Complex Cracking in Plain Weave C/SiC Composite under Biaxial Loading

    Cheng, Ron-Bin; Hsu, Su-Yuen

    2012-01-01

    Finite element analysis is performed on a mesh, based on computed geometry of a plain weave C/SiC composite with assumed internal stacking, to reveal the pattern of internal damage due to biaxial normal cyclic loading. The simulation encompasses intertow matrix cracking, matrix cracking inside the tows, and separation at the tow-intertow matrix and tow-tow interfaces. All these dissipative behaviors are represented by traction-separation cohesive laws. Not aimed at quantitatively predicting the overall stress-strain relation, the simulation, however, does not take the actual process of fiber debonding into account. The fiber tows are represented by a simple rule-of-mixture model where the reinforcing phase is a hypothetical one-dimensional material. Numerical results indicate that for the plain weave C/SiC composite, 1) matrix-crack initiation sites are primarily determined by large intertow matrix voids and interlayer tow-tow contacts, 2) the pattern of internal damage strongly depends on the loading path and initial stress, 3) compressive loading inflicts virtually no damage evolution. KEY WORDS: ceramic matrix composite, plain weave, cohesive model, brittle failure, smeared crack model, progressive damage, meso-mechanical analysis, finite element.

  13. Transient Dynamic Response and Failure of Sandwich Composite Structures under Impact Loading with Fluid Structure Interaction

    Kwon, Y. W.; Violette, M. A.; McCrillis, R. D.; Didoszak, J. M.

    2012-12-01

    The objective of this study is to examine the Fluid Structure Interaction (FSI) effect on transient dynamic response and failure of sandwich composite structures under impact loading. The primary sandwich composite used in this study consisted of a 6.35 mm balsa core and a multi-ply symmetrical plain weave 6 oz E-glass skin. Both clamped sandwich composite plates and beams were studied using a uniquely designed vertical drop-weight testing machine. There were three impact conditions on which these experiments focused. The first of these conditions was completely dry (or air surrounded) testing. The second condition was completely water submerged. The final condition was also a water submerged test with air support at the backside of the plates. The tests were conducted sequentially, progressing from a low to high drop height to determine the onset and spread of damage to the sandwich composite when impacted with the test machine. The study showed the FSI effect on sandwich composite structures is very critical such that impact force, strain response, and damage size are generally much greater with FSI under the same impact condition. As a result, damage initiates at much lower impact energy conditions with the effect of FSI. Neglecting to account for FSI effects on sandwich composite structures results in very non-conservative analysis and design. Additionally, it was observed that the damage location changed for sandwich composite beams with the effect of FSI.

  14. Effect of fiber loading on mechanical and morphological properties of cocoa pod husk fibers reinforced thermoplastic polyurethane composites

    Highlights: • Increase in fiber loading increased tensile strength and modulus of the composites. • Tensile strain was decreasing with increase in fiber loading. • Flexural strength and modulus increased with increase in fiber content. • Impact strength was deteriorated with increasing fiber loading. • Morphology observations shown a good adhesion between fibers and matrix. - Abstract: In this study, cocoa (Theobroma cacao) pod husk (CPH) fiber reinforced thermoplastic polyurethane (TPU) was prepared by melt compounding method using Haake Polydrive R600 internal mixer. The composites were prepared with different fiber loading: 20%, 30% and 40% (by weight), with the optimum processing parameters: 190 °C, 11 min, and 40 rpm for temperature, time and speed, respectively. Five samples were cut from the composite sheet. Mean value was taken for each composite according to ASTM standards. Effect of fiber loading on mechanical (i.e. tensile, flexural properties and impact strength) and morphological properties was studied. TPU/CPH composites showed increase in tensile strength and modulus with increase in fiber loading, while tensile strain was decreasing with increase in fiber loading. The composite also showed increase in flexural strength and modulus with increase in fiber content. Impact strength was deteriorated with increase in fiber loading. Morphology observations using Scanning Electron Microscope (SEM) showed fiber/matrix good adhesion

  15. Epoxy-acrylic core-shell particles by seeded emulsion polymerization.

    Chen, Liang; Hong, Liang; Lin, Jui-Ching; Meyers, Greg; Harris, Joseph; Radler, Michael

    2016-07-01

    We developed a novel method for synthesizing epoxy-acrylic hybrid latexes. We first prepared an aqueous dispersion of high molecular weight solid epoxy prepolymers using a mechanical dispersion process at elevated temperatures, and we subsequently used the epoxy dispersion as a seed in the emulsion polymerization of acrylic monomers comprising methyl methacrylate (MMA) and methacrylic acid (MAA). Advanced analytical techniques, such as scanning transmission X-ray microscopy (STXM) and peak force tapping atomic force microscopy (PFT-AFM), have elucidated a unique core-shell morphology of the epoxy-acrylic hybrid particles. Moreover, the formation of the core-shell morphology in the seeded emulsion polymerization process is primarily attributed to kinetic trapping of the acrylic phase at the exterior of the epoxy particles. By this new method, we are able to design the epoxy and acrylic polymers in two separate steps, and we can potentially synthesize epoxy-acrylic hybrid latexes with a broad range of compositions. PMID:27078740

  16. Preparation and properties of UV curable acrylic PSA by vinyl bonded graphene oxide

    Pang, Beili; Ryu, Chong-Min; Jin, Xin; Kim, Hyung-Il

    2013-11-01

    Acrylic pressure sensitive adhesives (PSAs) with higher thermal stability for thin wafer handling were successfully prepared by forming composite with the graphene oxide (GO) nanoparticles modified to have vinyl groups via subsequent reaction with isophorone diisocyanate and 2-hydroxyethyl methacrylate. The acrylic copolymer was synthesized as a base resin for PSAs by solution radical polymerization of ethyl acrylate, 2-ethylhexyl acrylate, and acrylic acid followed by further modification with GMA to have the vinyl groups available for UV curing. The peel strength of PSA decreased with the increase of gel content which was dependent on both modified GO content and UV dose. Thermal stability of UV-cured PSA was improved noticeably with increasing the modified GO content mainly due to the strong and extensive interfacial bonding formed between the acrylic copolymer matrix and GO fillers

  17. Experimental studies on fatigue behavior of macro fiber composite (MFC) under mechanical loading

    Pandey, Akash; Arockiarajan, A.

    2016-04-01

    Macro fiber Composite (MFC) finds its application in active control, vibration control and sensing elements. MFC can be laminated to surfaces or embedded in the structures to be used as an actuator and sensors. Due to its attractive properties and applications, it may be subjected to continuous loading, which leads to the deterioration of the properties. This study is focused on the fatigue lifetime of MFC under tensile and compressive loading at room temperature. Experiments were performed using 4 point bending setup, with MFC pasted at the center of the mild steel beam, to maintain constant bending stress along MFC. MFC is pasted using vacuum bagging technique. Sinusoidal loading is given to sample while maintaining R=0.13 (for tensile testing) and R=10 (for compressive testing). For d31 and d33 type of MFC, test was conducted for the strain values of 727 μ strain, 1400 μ strain, 1700 μ strain and 1900 μ strain for fatigue under tensile loading. For fatigue under compressive loading, both d33 and d31, was subjected to minimum strain of -2000 μ strain. Decrease in the slope of dielectric displacement vs. strain is the measure for the degradation. 10 percent decrease in the slope is set as the failure criteria. Experimental results show that MFC is very reliable below 1700 μ strain (R=0.13) at the room temperature.

  18. Dynamic Fracture of Nanocomposites and Response of Fiber Composite Panels to Shock Loading

    Shukla, Arun

    2009-06-01

    This lecture will present studies on the response of novel engineering materials to extreme dynamic loadings. In particular, the talk will focus on the behavior of sandwich composite materials to shock loading and dynamic fracture of nano-composite materials. Results from an experimental study on the response of sandwich materials to controlled blast loading will be presented. In this study, a shock tube facility was utilized to apply blast loading to simply supported plates of E-glass vinyl ester/PVC foam sandwich composite materials. Pressure sensors were mounted at the end of the muzzle section of the shock tube to measure the incident pressure and the reflected pressure profiles during the experiment. A high speed digital camera was utilized to capture the real time side deformation of the materials, as well as the development and progression of damage. Macroscopic and microscopic examination was then implemented to study the post-mortem damage. Conclusions on the relative performance of sandwich composites under blast loadings will also be discussed. Results from an experimental investigation conducted to evaluate the mechanical properties of novel materials fabricated using nano sized particles in polymer matrix will also be presented. Unsaturated polyester resin specimens embedded with small loadings of nano sized particles of TiO2 and Al2O3 were fabricated using a direct ultrasonification method to study the effects of nanosized particles on nanocomposite fracture properties. The ultrasonification method employed produced nanocomposites with excellent particle dispersion as verified by TEM. Experiments were conducted to investigate the dynamic crack initiation and rapid crack propagation in theses particle reinforced materials. High-speed digital imaging was employed along with dynamic photoelasticity to obtain real time, full-field quantification of the stress field associated with the dynamic fracture process. Birefringent coatings were used to conduct

  19. Effect of Load Rate on Ultimate Tensile Strength of Ceramic Matrix Composites at Elevated Temperatures

    Choi, Sung R.; Gyekenyesi, John P.

    2001-01-01

    The strengths of three continuous fiber-reinforced ceramic composites, including SiC/CAS-II, SiC/MAS-5 and SiC/SiC, were determined as a function of test rate in air at 1100 to 1200 C. All three composite materials exhibited a strong dependency of strength on test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress loading) suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law type of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology even for composite materials, at least for short range of lifetimes and when ultimate strength is used as the failure criterion.

  20. Effect of Piezoelectric Implant on the Structural Integrity of Composite Laminates Subjected to Tensile Loads

    Masmoudi, Sahir; El Mahi, Abderrahim; Turki, Saïd

    2016-07-01

    The embedment of sensors within composite structures gives the opportunity to develop smart materials for health and usage monitoring systems. This study investigates the use of acoustic emission monitoring with embedded piezoelectric sensor during mechanical tests in order to identify the effects of introducing the sensor into the composite materials. The composite specimen with and without embedded sensor were subject to tensile static and fatigue loading. The analysis and observation of AE signals show that the integration of a sensor presents advantage of the detection of the acoustic events and also show the presence of three or four types of damage during tests. The incorporation of piezoelectric sensor has a negligible influence on the mechanical properties of materials.

  1. Nonlinear Viscoelastic Response of Unidirectional Polymeric Laminated Composite Plates Under Bending Loads

    Falahatgar, S. R.; Salehi, Manouchehr

    2011-12-01

    Nonlinear bending analysis of polymeric laminated composite plate is examined considering material nonlinearity for viscoelastic matrix material through a Micro-macro approach. The micromechanical Simplified Unit Cell Method (SUCM) in three-dimensional closed-form solution is used for the overall behavior of the unidirectional composite in any combination of loading conditions. The elastic fibers are transversely isotropic where Schapery single integral equation in multiaxial stress state describes the matrix material by recursive-iterative formulation. The finite difference Dynamic Relaxation (DR) method is utilized to study the bending behavior of Mindlin annular sector plate including geometric nonlinearity under uniform lateral pressure with clamped and hinged edge constraints. The unsymmetrical laminated plate deflection is predicted for different thicknesses and also various pressures in different time steps and they are compared with elastic finite element results. As a main objective, the deflection results of viscoelastic laminated sector plate are obtained for various fiber volume fractions in the composite system.

  2. Combined effects of organic aerosol loading and fog processing on organic aerosols oxidation and composition

    Chakraborty, Abhishek; Tripathi, Sachchida; Gupta, Tarun

    2016-04-01

    Fog is a natural meteorological phenomenon that occurs throughout the world, it contains substantial quantity of liquid water and generally seen as a natural cleansing agent but it also has the potential to form highly oxidized secondary organic aerosols (SOA) via aqueous processing of ambient aerosols. On the other hand higher organic aerosols (OA) loading tend to decrease the overall oxidation level (O/C) of the particle phase organics, due to enhanced partitioning of less oxidized organics from gas to particle phase. However, combined impact of these two parameters; aqueous oxidation and OA loading, on the overall oxidation ratio (O/C) of ambient OA has never been studied. To assess this, real time ambient sampling using HR-ToF-AMS was carried out at Kanpur, India from 15 December 2014 - 10 February 2015. In first 3 weeks of this campaign, very high OA loading is (134 ± 42 μg/m3) observed (termed as high loading or HL period) while loading is substantially reduced from 2nd January, 2016 (56 ± 20 μg/m3, termed as low loading or LL period) . However, both the loading period was affected by several fog episodes (10 in HL and 7 in LL), thus providing the opportunity of studying the combined effects of fog and OA loading on OA oxidation. It is found that O/C ratio is very strongly anti-correlated with OA loading in both the loading period, however, slope of this ant-correlation is much steep during HL period than in LL period. Source apportionment of OA revealed that there is drastic change in the types of OA from HL to LL period, clearly indicating difference in OA composition from HL to LL period. During foggy night continuous oxidation of OA is observed from early evening to early morning with 15-20% enhancement in O/C ratio, while the same is absent during non-foggy period, clearly indicating the efficient fog processing of ambient OA. It is also found that night time fog aqueous oxidation can be as effective as daytime photo chemistry in oxidation of OA. Fog

  3. Effect of Fiber Treatment and Fiber Loading on Mechanical Properties of Luffa-Resorcinol Composites

    Chhatrapati Parida

    2015-01-01

    Full Text Available Tensile and compressive behaviour of resorcinol-formaldehyde (RF matrix and its composites reinforced with fibers of Luffa cylindrica (LC have been studied. LC fibers were subjected to chemical treatments such as alkali activation by NaOH followed by bleaching and acid hydrolysis in order to improve fiber-matrix adhesion. Both treated and untreated LC fibers are modified with calcium phosphate. The presence of hydroxy apatite, a polymorph of calcium phosphate and a major constituent of vertebrate bone and teeth, was confirmed from XRD peak of treated LC fiber. XRD analysis of the treated LC fiber has confirmed the crystalline nature of the chemically treated LC fiber by its crystallinity index. The effects of fiber loading of chemically treated and untreated LC fiber on ultimate stress, yield strength, breaking stress, and modulus of the composites were analyzed. The tensile and compressive modulus of the composites were increased with incorporation of both treated and untreated LC fibers into the RF matrix. The modulus of composites with treated LC fiber was enhanced compared to that of the untreated fiber composites. Furthermore the values of ultimate stress, yield stress, and breaking stress were increased with the incorporation of treated LC fiber in the composites.

  4. Acrylic Acid and Esters Will Be Oversupply

    Zheng Chengwang

    2007-01-01

    @@ Drastic capacity growth The production capacity of acrylic acid in China has grown drastically in recent years. With the completion of the 80 thousand t/a acrylic acid and 130 thous and t/a acrylic ester project in Shenyang Paraffin Chemical Industrial Co., Ltd., (CCR2006,No. 31) the capacity of acrylic acid in China has reached 882 thousand t/a.

  5. Preparation and properties of acrylic resin coating modified by functional graphene oxide

    Dong, Rui; Liu, Lili

    2016-04-01

    To improve the dispersion and the strength of filler-matrix interface in acrylic resin, the functional graphene oxide (FGO) was obtained by surface modification of graphene oxide (GO) by γ-methacryloxypropyl trimethoxysilane (KH-570) and then the acrylic nanocomposites containing different loadings of GO and FGO were prepared. The structure, morphology and dispersion/exfoliation of the FGO were characterized by XRD, FT-IR, Raman, XPS, SEM and TEM. The results demonstrated that the KH-570 was successfully grafted onto the surface of GO sheets. Furthermore, the corresponding thermal, mechanical and chemical resistance properties of the acrylic nanocomposites filled with the FGO were studied and compared with those of neat acrylic and GO/acrylic nanocomposites. The results revealed that the loading of FGO effectively enhanced various properties of acrylic resin. These findings confirmed that the dispersion and interfacial interaction were greatly improved by incorporation of FGO, which might be the result of covalent bonds between the FGO and the acrylic matrix. This work demonstrates an in situ polymerization method to construct a flexible interphase structure, strong interfacial interaction and good dispersion of FGO in acrylic nanocomposites, which can reinforce the polymer properties and be applied in research and industrial areas.

  6. Electrical and thermal response of carbon nanotube composites under quasi-static and dynamic loading

    O'Connell, Christopher D.

    Carbon nanotube (CNT) composites have attracted much interest due to their possible technical applications as conductive polymers and sensory materials. This study will consist of two major objectives: 1.) to investigate the thermal conductivity and thermal response of multi-wall carbon nanotube (MWCNT) composites under quasi-static loading, and 2.) to investigate the electrical response of carboxyl-terminated butadiene (CTBN) rubber-reinforced MWCNT/Epoxy composites under quasi-static and dynamic loading. Similar studies have shown that the electrical conductivity of CNT/Epoxy composites dramatically increases with compressive strains up to 15%. Part 1 seeks to find out if thermal conductivity show a similar response to electrical conductivity under an applied load. Part 2 seeks to investigate how the addition of rubber affects the mechanical and electrical response of the composite subjected to quasi-static and dynamic loading. By knowing how thermal and electrical properties change under a given applied strain, we attempt to broaden the breadth of understanding of CNT/epoxy composites and inqure the microscopic interactions occurring between the two. Electrical experiments sought to investigate the electrical response of rubber-reinforced carbon nanotube epoxy composites under quasi-static and dynamic loading. Specimens were fabricated with CTBN rubber content of 10 parts per hundredth resin (phr), 20 phr, 30 phr and 0 phr for a basis comparison. Both quasi-static and dynamic mechanical response showed a consistent decrease in peak stress and Young's modulus with increasing rubber content. Trends in the electrical response between each case were clearly observed with peak resistance changes ranging from 58% to 73% and with each peak occurring at a higher value with increasing rubber content, with the exception of the rubber-free specimens. It was concluded that among the rubber-embedded specimens, the addition of rubber helped to delay micro-cracking and

  7. Loading-dependent elemental composition of α-pinene SOA particles

    J. E. Shilling

    2009-02-01

    Full Text Available The chemical composition of secondary organic aerosol (SOA particles, formed by the dark ozonolysis of α-pinene, was characterized by a high-resolution time-of-flight aerosol mass spectrometer. The experiments were conducted using a continuous-flow chamber, allowing the particle mass loading and chemical composition to be maintained for several days. The organic portion of the particle mass loading was varied from 0.5 to >140 μg/m3 by adjusting the concentration of reacted α-pinene from 0.9 to 91.1 ppbv. The mass spectra of the organic material changed with loading. For loadings below 5 μg/m3 the unit-mass-resolution m/z 44 (CO2+ signal intensity exceeded that of m/z 43 (predominantly C2H3O+, suggesting more oxygenated organic material at lower loadings. The composition varied more for lower loadings (0.5 to 15 μg/m3 compared to higher loadings (15 to >140 μg/m3. The high-resolution mass spectra showed that from >140 to 0.5 μg/m3 the mass percentage of fragments containing carbon and oxygen (CxHyOz+ monotonically increased from 48% to 54%. Correspondingly, the mass percentage of fragments representing CxHy+ decreased from 52% to 46%, and the atomic oxygen-to-carbon ratio increased from 0.29 to 0.45. The atomic ratios were accurately parameterized by a four-product basis set of decadal volatility (viz. 0.1, 1.0, 10, 100 μg/m3 employing products having empirical formulas of C1H1.32O0.48, C1H1.36O0.39, C1H1.57O0.24, and C1H1.76O0.14. These findings suggest considerable caution is warranted in the extrapolation of laboratory results that were obtained under conditions of relatively high loading (i

  8. Temperature effects on polymer-carbon composite sensors: evaluating the role of polymer molecular weight and carbon loading

    Homer, M. L.; Lim, J. R.; Manatt, K.; Kisor, A.; Lara, L.; Jewell, A. D.; Yen, S. -P. S.; Shevade, A. V.; Ryan, M. A.

    2003-01-01

    We report the effect of environmental condtions coupled with varying polymer properties and carbon loadings on the performance of polymer-carbon black composite film, used as sensing medium in the JPL Electronic Nose.

  9. Optical performance of mesostructured composite silica film loaded with organic dye.

    Guli, Mina; Chen, Shijian; Zhang, Dingke; Li, Xiaotian; Yao, Jianxi; Chen, Lei; Xiao, Li

    2014-01-10

    A mesoporous composite silica film loaded with organic dye has been successfully synthesized by a solgel reaction process and a simple postgrafting method at room temperature. The composite film was characterized by x-ray diffraction, transmission electron microscopy, UV-Vis, photoluminescence (PL) spectra, and laser performance, and the results confirmed the existence of dyes in the channels of the silica film. A blue-shift and fluorescence property in the PL spectrum was observed from the composite film compared with that of dye molecules in C₂H₅OH solution. The spectrum narrowing phenomena has been observed when the composite film is pumped at λp=355  nm by a Nd:YAG pulsed laser. A narrower, higher peak was observed in emission spectra from the mesostructured composite silica film compared with the PL spectrum of dye in C₂H₅OH solution. There is a substantial reduction in the full width at half-maximum of the emitting light, which results in peaks with linewidths of 26 nm or more. This collapse of the emission spectrum is one of the signatures of the presence of amplified spontaneous emission. PMID:24514063

  10. Health Monitoring of a Composite Actuator with a PZT Ceramic during Electromechanical Fatigue Loading

    This work describes an investigation into the feasibility of using an acoustic emission (AE) technique to evaluate the integrity of a composite actuator with a PZT ceramic under electromechanical cyclic loading. AE characteristics have been analyzed in terms of the behavior of the AE count rate and signal waveform in association with the performance degradation of the composite actuator during the cyclic tests. The results showed that the fatigue cracking of the composite actuator with a PZT ceramic occurred only in the PZT ceramic layer, and that the performance degradation caused by the fatigue damage varied immensely depending on the existence of a protecting composite bottom layer. We confirmed the correlations between the fatigue damage mechanisms and AE signal types for the actuators that exhibited multiple modes of fatigue damage; transgranular micro damage, intergranular fatigue cracking, and breakdown by a short circuiting were related to a burst type signal showing a shortly rising and slowly decaying waveform with a comparably low voltage, a continuous type signal showing a gradual rising and slowly decaying waveform with a very high voltage and a burst and continuous type signal with a high voltage, respectively. Results from the present work showed that the evolution of fatigue damage in the composite actuator with a PZT ceramic can be nondestructively identified via in situ AE monitoring and microscopic observations