Salting by vacuum brine impregnation in nitrite-free lonza: effect on Enterobacteriaceae

Directory of Open Access Journals (Sweden)

Annalisa Serio

2017-01-01

Full Text Available Lonza is a traditional Italian meat product made from whole pork muscles, which is typically cured by dry salting. In this work, we study the effects of vacuum brine impregnation (VBI as an alternative salting method on the survival of Enterobacteriaceae, in presence and in absence of nitrites. In comparison with the traditional brining process, VBI contributed to reducing the Enterobacteriaceae population on product surface but induced contamination of the inner muscle tissues. Our results suggest that the species isolated became adapted to processing conditions, and salt tolerance was species- or straindependent. This result is of particular importance for future applications of VBI in lonza manufacturing.

Influence of vacuum impregnation and pulsed electric field on the freezing temperature and ice propagation rates of spinach leaves

Science.gov (United States)

Efforts are currently directed towards improving the quality of sensitive tissues of fruits and vegetables after freezing and thawing. One of the methods under investigation is the combination of vacuum impregnation (VI) with cryoprotectants and pulsed electric field (PEF) applied to the plant tiss...

Resin impregnation process for producing a resin-fiber composite

Science.gov (United States)

Palmer, Raymond J. (Inventor); Moore, William E. (Inventor)

1994-01-01

Process for vacuum impregnation of a dry fiber reinforcement with a curable resin to produce a resin-fiber composite, by drawing a vacuum to permit flow of curable liquid resin into and through a fiber reinforcement to impregnate same and curing the resin-impregnated fiber reinforcement at a sufficient temperature and pressure to effect final curing. Both vacuum and positive pressure, e.g. autoclave pressure, are applied to the dry fiber reinforcement prior to application of heat and prior to any resin flow to compact the dry fiber reinforcement, and produce a resin-fiber composite of reduced weight, thickness and resin content, and improved mechanical properties. Preferably both a vacuum and positive pressure, e.g. autoclave pressure, are also applied during final curing.

Optimization of Vacuum Impregnation with Calcium Lactate of Minimally Processed Melon and Shelf-Life Study in Real Storage Conditions.

Science.gov (United States)

Tappi, Silvia; Tylewicz, Urszula; Romani, Santina; Siroli, Lorenzo; Patrignani, Francesca; Dalla Rosa, Marco; Rocculi, Pietro

2016-10-05

Vacuum impregnation (VI) is a processing operation that permits the impregnation of fruit and vegetable porous tissues with a fast and more homogeneous penetration of active compounds compared to the classical diffusion processes. The objective of this research was to investigate the impact on VI treatment with the addition of calcium lactate on qualitative parameters of minimally processed melon during storage. For this aim, this work was divided in 2 parts. Initially, the optimization of process parameters was carried out in order to choose the optimal VI conditions for improving texture characteristics of minimally processed melon that were then used to impregnate melons for a shelf-life study in real storage conditions. On the basis of a 2 3 factorial design, the effect of Calcium lactate (CaLac) concentration between 0% and 5% and of minimum pressure (P) between 20 and 60 MPa were evaluated on color and texture. Processing parameters corresponding to 5% CaLac concentration and 60 MPa of minimum pressure were chosen for the storage study, during which the modifications of main qualitative parameters were evaluated. Despite of the high variability of the raw material, results showed that VI allowed a better maintenance of texture during storage. Nevertheless, other quality traits were negatively affected by the application of vacuum. Impregnated products showed a darker and more translucent appearance on the account of the alteration of the structural properties. Moreover microbial shelf-life was reduced to 4 d compared to the 7 obtained for control and dipped samples. © 2016 Institute of Food Technologists®.

Measurement of inter-strand contact resistance in epoxy impregnated Nb3Sn Rutherford cables

International Nuclear Information System (INIS)

Giorgio Ambrosio

2003-01-01

An apparatus for the measurement, under transverse pressure, of the inter-strand contact resistance in epoxy-impregnated Nb 3 Sn Rutherford cables has been recently assembled at Fermilab. Procedures have been developed to instrument and measure samples extracted from Nb 3 Sn coils. Samples were extracted from coils fabricated with the Wind-and-React and the React-and-Wind technology, both presently under development at Fermilab. A ceramic binder is used to improve the insulation and to simplify the fabrication of coils using the Wind-and-React technology. Synthetic oil is used to prevent sintering during the heat treatment of coils to be wound after reaction. In order to evaluate the effects of the ceramic binder and of the synthetic oil on the inter-strand resistance, measurements of samples extracted from coils were compared with measurements of cable stacks with varying characteristics. In this paper we describe the apparatus, the sample preparation, the measurement procedure, and the results of the first series of tests

Impregnation of Graphite with Liquid Silicon in a Vacuum; Impregnation du graphite avec du silicium llquide sous vide; Propitka grafita kremniem v vakuume; Impregnacion de grafito con silicio liquido en el vacio

Energy Technology Data Exchange (ETDEWEB)

Ivanov, V. E.; Zelenskij, V. F.; Kolendovskij, M. K.; Kolomiets, L. D.

1963-11-15

A study was made of the possibility of producing high thermal resistance graphite-silicon carbide materials by means of impregnating MG graphite with liquid silicon in a vacuum. An attempt is made to explain the mechanism and origins of the degradation of products during the impregnation process. On the basis of their researches the authors put forward a number of technical requirements, observance of which make it possible to produce graphite-silicon carbide materials by means of impregnation of graphite with liquid silicon-in a vacuum at temperatures of 1450 to 1600 deg. C. (author) [French] Les auteurs etudient la possibilite d'obtenir, en impregnant du graphite MG avec du silicium liquide sous vide, des materiaux au graphite, carbure et silicium resistants a la chaleur. Ils cherchent a expliquer le mecanisme et les causes de la destruction des produits au cours de l'impregnation. Se fondant sur les resultats de leurs recherches, ils enoncent un certain nombre de conditions technologiques a remplir pour obtenir les materiaux en question en impregnant le graphite de silicium liquide sous vide, a une temperature de l'ordre de 1450 a 1600 deg. C. (author) [Spanish] Los autores han estudiado la posibilidad de preparar materiales de grafito y carburo de silicio de elevada resistencia termica impregnando grafito marca MG con silicio liquido en el vacio. Proponen una explicacion del mecanismo y de las causas de la degradacion de los productos durante la impregnacion. Sobre la base de las investigaciones realizadas, los autores enumeran una serie de condiciones tecnologicas cuyo cumplimiento permite preparar piezas de grafito y carburo de silicio, impregnando el grafito con silicio liquido en el vacio a temperaturas comprendidas entre 1450 y 1600 deg. C. [Russian] V rabote izuchalas' vozmozhnost' sozdaniya grafit-karbidkremnievykh materialov s povyshennoj termostojkost'yu putem propitki grafita marki MG zhidkim kremniem v vakuume. Sdelana popytka ob{sup y

Effect of epoxy impregnation on strain distribution of materials in Bi2223 superconducting coils by using synchrotron X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Jin, Xinzhe, E-mail: xinzhe.jin@riken.jp [Center for Life Science Technologies, RIKEN, Yokohama-shi, Kanagawa 230-0045 (Japan); Osamura, Kozo [Research Institute for Applied Sciences, Sakyo-ku, Kyoto 606-8202 (Japan); Machiya, Shutaro [Daido University, Minami-ku, Nagoya 457-8530 (Japan); Kajiwara, Kentaro [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Shobu, Takahisa [Japan Atomic Energy Agency, Sayo, Hyogo 679-5148 (Japan); Maeda, Hideaki [Center for Life Science Technologies, RIKEN, Yokohama-shi, Kanagawa 230-0045 (Japan)

2015-11-25

Synchrotron X-rays have been used to observe strain distributions in composite materials such as superconducting wires with a thickness of less than about 2 mm. In applications that employ wound coils of superconducting wire, it is necessary to understand the strain distribution within the coiled wire. Superconducting wires such as Bi2223 and REBCO wires approximately 4–5 mm wide are commercially available. Coiled wires of this width are too thick to easily measure using conventional X-ray techniques, especially the inner strain, because the penetration depth tends to be around 2 mm. Therefore, the beam penetration must be improved, and it is known that the penetration depth of an X-ray beam depends upon the beam energy, beam intensity, measurement material, and measurement method. In this study, we used a white X-ray diffractometer at SPring-8 to develop a method of observing the strain distribution in Bi2223 superconducting coils winded by a 4.5 mm wide Bi2223 wire. We successfully observed a clear (400) peak of the Bi2223 phase by an appropriate measurement condition, and then observed the strains of each material in the Bi2223 coils with and without epoxy impregnation. This is the first time that we have obtained the strain of a Bi2223 phase in coiled wire using synchrotron X-ray diffraction. Further synchrotron-based study of superconducting coils will be useful in the development of advanced high-field magnets. The appropriate measurement method and the obtained measurement results are presented in this paper. - Highlights: • We successfully obtained clear peaks of Bi2223 phase in 4.5 mm thick coils. • The strain behaviors of materials in the coil correspond to a three turn cycle model. • A uniform strain distribution of the Bi2223 phase was obtained by epoxy impregnation.

Impact of impregnation with boron compounds on combustion ...

African Journals Online (AJOL)

This study examined the impacts of varnishing after impregnation with boron compounds on combustion properties of oriental beech. The test samples prepared from oriental beech (Fagus orientalis Lipsky) wood were impregnated according to ASTM D 1413–76–99 with boric acid (Ba) or borax (Bx) using a vacuum ...

Effects of impregnation methods and drying conditions on quinoline hydrodenitrogenation over Ni-W based catalysts

Energy Technology Data Exchange (ETDEWEB)

Guo, Fang; Qiu, Zegang; Zhao, Liangfu; Xiang, Hongwei [Institute of Coal Chemistry, Chinese Academy of Sciences (China); Guo, Shaoqing [Taiyuan University of Science and Technology (China)

2014-04-15

The effects of impregnation methods (co-impregnation and sequential impregnation) and drying conditions (air and vacuum) on the structure and catalytic behavior of MCM-41 supported Ni-W catalysts were investigated. The catalysts were characterized by powder X-ray diffraction (XRD) analysis, Fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance UV-Vis absorbance spectroscopy (DRS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and pyridine adsorbed infrared spectroscopy (Py-IR) techniques. They were tested for hydrodenitrogenation (HDN) of quinoline at temperatures of 300-400 deg C. The HDN results showed that the catalysts prepared by co-impregnation were more active than the catalysts prepared by sequential impregnation and the catalysts prepared by drying under vacuum were more active than the catalysts dried in air. Characterization revealed that the co-impregnation method and drying under vacuum promoted the dispersion of W, the formation of the active phases, and the formation of acidic sites on the catalysts. (author)

Recent progress and tests of radiation resistant impregnation materials for Nb3Sn coils

International Nuclear Information System (INIS)

Bossert, R.; Krave, S.; Ambrosio, G.; Andreev, N.; Chlachidze, G.; Nobrega, A.; Novitski, I.; Yu, M.; Zlobin, A. V.

2014-01-01

Fermilab is collaborating with Lawrence Berkeley National Laboratory (LBNL) and Brookhaven National Laboratory (BNL) (US-LARP collaboration) to develop a large-aperture Nb 3 Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. An important component of this work is the development of materials that are sufficiently radiation resistant for use in critical areas of the upgrade. This paper describes recent progress in characterization of materials, including the baseline CTD101K epoxy, cyanate ester blends, and Matrimid 5292, a bismaleimide-based system. Structural properties of “ten stacks” of cable impregnated with these materials are tested at room and cryogenic temperatures and compared to the baseline CT-101K. Experience with potting 1 and 2 meter long coils with Matrimid 5292 are described. Test results of a single 1-m coil impregnated with Matrimid 5292 are reported and compared to similar coils impregnated with the traditional epoxy

Recent progress and tests of radiation resistant impregnation materials for Nb3Sn coils

Science.gov (United States)

Bossert, R.; Krave, S.; Ambrosio, G.; Andreev, N.; Chlachidze, G.; Nobrega, A.; Novitski, I.; Yu, M.; Zlobin, A. V.

2014-01-01

Fermilab is collaborating with Lawrence Berkeley National Laboratory (LBNL) and Brookhaven National Laboratory (BNL) (US-LARP collaboration) to develop a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. An important component of this work is the development of materials that are sufficiently radiation resistant for use in critical areas of the upgrade. This paper describes recent progress in characterization of materials, including the baseline CTD101K epoxy, cyanate ester blends, and Matrimid 5292, a bismaleimide-based system. Structural properties of "ten stacks" of cable impregnated with these materials are tested at room and cryogenic temperatures and compared to the baseline CT-101K. Experience with potting 1 and 2 meter long coils with Matrimid 5292 are described. Test results of a single 1-m coil impregnated with Matrimid 5292 are reported and compared to similar coils impregnated with the traditional epoxy.

System and method for preventing stator permanent magnet demagnetization during vacuum pressure impregnation

Science.gov (United States)

Raminosoa, Tsarafidy; Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi

2017-06-06

A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing step that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.

Effects of impregnation with boron compounds on the surface ...

African Journals Online (AJOL)

Liebl.) which met the requirements of ASTM D 358 were impregnated according to ASTM D 1413 with boric acid (Ba) and borax (Bx) by vacuum technique. After impregnation, surfaces were coated with cellulosic, synthetic, polyurathane, water-based, acrylic and acid hardening varnishes in accordance with ASTM D 3023 ...

Effect of vacuum and temperature on the mechanical properties of an aramid/epoxy composite

International Nuclear Information System (INIS)

Hahn, H.T.; Chin, W.K.

1981-01-01

The mechanical properties of a Kevlar 49/epoxy composite intended for flywheel applications are investigated in the laboratory and simulated service environments. The filament-wound composites were preconditioned in the test environment for 1-5 months, during which weight change was monitored, then subjected to tensile and fatigue tests at room temperature or 75 deg in vacuum. A weight loss of only 1.63% is observed after 11 months in the simulated service environment, most of which is attributed to moisture desorbed in vacuum. In contrast to air at 75 C, the simulated service environment is also found to produce no deleterious effects on static and fatigue strengths, probably to moisture desorption and a lack of oxidation. A fatigue life of about 100,000 cycles for 95% survival proability is obtained at 70% of the average static strength, and the macroscopic failure mode, which results in a brush-like formation, is observed to be independent of the type of loading and preconditioning. It is concluded that an environment of 75 C in vacuum is no deterrent to the application of the composite in flywheels, however the possibility of increasing service temperature to 150 C should be investigated

Impregnation of soft biological specimens with thermosetting resins and elastomers.

Science.gov (United States)

von Hagens, G

1979-06-01

A new method for impregnation of biological specimens with thermosetting resins and elastomers is described. The method has the advantage that the original relief of the surface is retained. The impregnation is carried out by utilizing the difference between the high vapor tension of the intermedium (e.g., methylene chloride) and the low vapor tension of the solution to be polymerized. After impregnation, the specimen is subject to polymerization conditions without surrounding embedding material. The optical and mechanical properties can be selected by proper choice from various kinds of resins and different procedures, for example, by complete or incomplete impregnation. Acrylic resins, polyester resins, epoxy resins, polyurethanes and silicone rubber have been found suitable for the method. Excellent results have been obtained using transparent silicone rubber since after treatment the specimens are still flexible and resilient, and have retained their natural appearance.

Manufacturing of REBCO coils strongly bonded to cooling members with epoxy resin aimed at its application to Maglev

International Nuclear Information System (INIS)

Mizuno, Katsutoshi; Ogata, Masafumi; Hasegawa, Hitoshi

2014-01-01

Highlights: • Paraffin has a risk of losing thermal coupling during cooling down. • We propose an epoxy impregnated REBCO coil co-wound with PTFE tape. • The coil is tightly bonded to cooling members by epoxy resin without the degradation. • We made a REBCO racetrack coil with the same outer dimension as the Maglev magnet. - Abstract: The REBCO coated conductor has been attracted attention because of its high current density in the presence of high magnetic field. If the coated conductor is applied to Maglev, the operational temperature of the on-board magnets will be over 40 K and energy consumption of cryocoolers will be reduced. That high operational temperature also means the absence of liquid helium. Therefore, reliable thermal coupling is desirable for cooling the coils. We propose an epoxy impregnated REBCO coil co-wound with PTFE tape. While the PTFE tape prevents the performance degradation of the coil, the epoxy resin bonds the coil to cooling members. We carried out three experiments to confirm that the coil structure which we propose has robust thermal coupling without the degradation. First, thermal resistances of paraffin and epoxy were measured varying the temperature from room temperature to 10 K. The measurement result indicates that paraffin has a risk of losing thermal coupling during cooling down. In another experiment, PTFE (polytetrafluoroethylene) tape insulator prevented performance degradation of a small epoxy impregnated REBCO coil, while another REBCO coil with polyimide tape showed clear performance degradation. Finally, we produced a racetrack REBCO coil with the same outer dimension as a Maglev on-board magnet coil. Although the racetrack coil was installed in a GFRP coil case and tightly bonded to the case by epoxy impregnation, any performance degradation was not observed

Manufacturing of REBCO coils strongly bonded to cooling members with epoxy resin aimed at its application to Maglev

Energy Technology Data Exchange (ETDEWEB)

Mizuno, Katsutoshi, E-mail: mizuno.katsutoshi.14@rtri.or.jp; Ogata, Masafumi; Hasegawa, Hitoshi

2014-11-15

Highlights: • Paraffin has a risk of losing thermal coupling during cooling down. • We propose an epoxy impregnated REBCO coil co-wound with PTFE tape. • The coil is tightly bonded to cooling members by epoxy resin without the degradation. • We made a REBCO racetrack coil with the same outer dimension as the Maglev magnet. - Abstract: The REBCO coated conductor has been attracted attention because of its high current density in the presence of high magnetic field. If the coated conductor is applied to Maglev, the operational temperature of the on-board magnets will be over 40 K and energy consumption of cryocoolers will be reduced. That high operational temperature also means the absence of liquid helium. Therefore, reliable thermal coupling is desirable for cooling the coils. We propose an epoxy impregnated REBCO coil co-wound with PTFE tape. While the PTFE tape prevents the performance degradation of the coil, the epoxy resin bonds the coil to cooling members. We carried out three experiments to confirm that the coil structure which we propose has robust thermal coupling without the degradation. First, thermal resistances of paraffin and epoxy were measured varying the temperature from room temperature to 10 K. The measurement result indicates that paraffin has a risk of losing thermal coupling during cooling down. In another experiment, PTFE (polytetrafluoroethylene) tape insulator prevented performance degradation of a small epoxy impregnated REBCO coil, while another REBCO coil with polyimide tape showed clear performance degradation. Finally, we produced a racetrack REBCO coil with the same outer dimension as a Maglev on-board magnet coil. Although the racetrack coil was installed in a GFRP coil case and tightly bonded to the case by epoxy impregnation, any performance degradation was not observed.

Fiber-Reinforced Epoxy Composites and Methods of Making Same Without the Use of Oven or Autoclave

Science.gov (United States)

Barnell, Thomas J. (Inventor); Rauscher, Michael D. (Inventor); Stienecker, Rick D. (Inventor); Nickerson, David M. (Inventor); Tong, Tat H. (Inventor)

2016-01-01

Method embodiments for producing a fiber-reinforced epoxy composite comprise providing a mold defining a shape for a composite, applying a fiber reinforcement over the mold, covering the mold and fiber reinforcement thereon in a vacuum enclosure, performing a vacuum on the vacuum enclosure to produce a pressure gradient, insulating at least a portion of the vacuum enclosure with thermal insulation, infusing the fiber reinforcement with a reactive mixture of uncured epoxy resin and curing agent under vacuum conditions, wherein the reactive mixture of uncured epoxy resin and curing agent generates exothermic heat, and producing the fiber-reinforced epoxy composite having a glass transition temperature of at least about 100.degree. C. by curing the fiber reinforcement infused with the reactive mixture of uncured epoxy resin and curing agent by utilizing the exothermically generated heat, wherein the curing is conducted inside the thermally insulated vacuum enclosure without utilization of an external heat source or an external radiation source.

An innovative process for the impregnation of magnet coils and other structures

International Nuclear Information System (INIS)

Evans, D.; Morgan, J.T.

1992-01-01

The need to bond and encapsulate the conductor in many types of superconductive magnet is well understood. The choice of materials for bonding may influence the performance of the coil and the technique used for its application. This paper considers the merits of three types of close-quote bonding close-quote procedure and presents details of an innovative method for the vacuum impregnation of coils. The process has been developed and evaluated in an attempt to remove some of the uncertainties of the vacuum impregnation process that traditionally may be eliminated only with the use of sealed mould tools and high quality vacuum chambers. For large magnets or for mass production, this process may lead to a reduction in tooling and plant costs, together with reduced resin consumption and improved health and safety factors. The process has been developed in conjunction with a resin system that has been designed to exhibit excellent thermal shock characteristics and to minimise preparation time and post impregnation cleaning requirements

Development and fabrication of a Bi-2223 racetrack coil for generator applications

International Nuclear Information System (INIS)

Herd, K.G.; Salasoo, L.; Laskaris, E.T.; Ranze, R.A.; King, C.G.

1996-01-01

The development and fabrication of a layer-wound, epoxy-impregnated Bi-2223 high-temperature superconducting (HTS) racetrack coil which generates 40,000 ampere-turns of magnetomotive force (MMF) at 25 K is described. The coil was wound using Ag-sheathed Bi-2223 tape conductor laminated with copper foils for strength enhancement and insulated using a paper-wrap method. After epoxy impregnation, the coil was tested over a range of 16--25 K in a vacuum dewar using a closed-cycle helium refrigeration system. Descriptions of the tape lamination and insulation processing, the coil winding and impregnation, and the experimental test setup are given

The edible cocktail: the effect of sugar and alcohol impregnation on the crunchiness of fruit

NARCIS (Netherlands)

Scholten, E.; Peters, M.M.J.P.

2012-01-01

Vacuum impregnation is seen as a valuable technique for flavor pairing in the catering industry. One of the applications of this technique is the creation of edible cocktails by impregnating of fruits with liquors, leading to an interplay of different flavors. However, the effect of the impregnation

A Mathematical Model of Repeated Impregnation of Porous Bodies with Solutions of Polymers

Directory of Open Access Journals (Sweden)

I. V. Glebov

2015-01-01

Full Text Available The paper describes basic methods of impregnating porous bodies with solutions of polymers and their use to manufacture prepregs. It also describes the existing methods of manufacturing multilayer prepregs to produce aerospace coating of the spacecraft "Soyuz". It is shown that these prepregs have to meet high requirements for the content of the polymer, as compared with other composite materials, about 35 - 40% of the mass. Methods used for their manufacturing are long-term and non-controllable. The assumption is made that using the vacuum impregnation technology of a woven material will allow to accelerate the manufacturing process of these prepregs and improve their quality.In reviewing the technical literature have been found works on modeling the processes of impregnation, but they are aimed only at studying the speed of the woven material impregnation by various fluids and determining the time of impregnation. There were no models found to define prepreg parameters during the process of multiple impregnations. The aim of this work is to develop the simple mathematical model, which enables us to predict the polymer content of volatile products in the prepreg after each cycle of multiple impregnation of woven material with a solution of the polymer.To consider the vacuum impregnation method are used the prepregs based on silica and silica-nylon stitch-bonding fabric and bakelite varnish LBS-4 containing 50 - 60% of phenol resin and the solvent with minor impurities of pure phenol and water, as an example. To describe the process of vacuum impregnation of the porous work-piece is developed a mathematical description of the process of filling the porous space of the material with a varnish. It is assumed that the varnish components fill the porous space of the material in the same proportion as they are contained in the varnish.It is shown that a single impregnation cannot ensure the content of phenol resin in the prepreg over 32%, which does

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

OpenAIRE

Naveh, Naum; Shepelev, Olga; Kenig, Samuel

2017-01-01

Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, ...

Manufacturing of REBCO coils strongly bonded to cooling members with epoxy resin aimed at its application to Maglev

Science.gov (United States)

Mizuno, Katsutoshi; Ogata, Masafumi; Hasegawa, Hitoshi

2014-11-01

The REBCO coated conductor has been attracted attention because of its high current density in the presence of high magnetic field. If the coated conductor is applied to Maglev, the operational temperature of the on-board magnets will be over 40 K and energy consumption of cryocoolers will be reduced. That high operational temperature also means the absence of liquid helium. Therefore, reliable thermal coupling is desirable for cooling the coils. We propose an epoxy impregnated REBCO coil co-wound with PTFE tape. While the PTFE tape prevents the performance degradation of the coil, the epoxy resin bonds the coil to cooling members. We carried out three experiments to confirm that the coil structure which we propose has robust thermal coupling without the degradation. First, thermal resistances of paraffin and epoxy were measured varying the temperature from room temperature to 10 K. The measurement result indicates that paraffin has a risk of losing thermal coupling during cooling down. In another experiment, PTFE (polytetrafluoroethylene) tape insulator prevented performance degradation of a small epoxy impregnated REBCO coil, while another REBCO coil with polyimide tape showed clear performance degradation. Finally, we produced a racetrack REBCO coil with the same outer dimension as a Maglev on-board magnet coil. Although the racetrack coil was installed in a GFRP coil case and tightly bonded to the case by epoxy impregnation, any performance degradation was not observed.

Void-free epoxy castings for cryogenic insulators and seals

International Nuclear Information System (INIS)

Quirk, J.F.

1983-01-01

The design of the Westinghouse Magnet for the Oak Ridge National Laboratory's Large Coil Program (LCP) incorporates a main lead bushing which transmits heat-leak loads by conduction to the supercritical helium stream. The bushing, which consists of epoxy resin cast about a copper conductor, must be electrically insulated, vacuum tight and be capable of withstanding the stresses encountered in cryognic service. The seal design of the bushing is especially important; leakage from either the helium system or the external environment into the vacuum will cause the magnet to quench. Additionally, the epoxy-resin casting must resist mechanical loads caused by the weight of leads attached to the bushing and thermal stresses transmitted to the epoxy via the conductor. The epoxy resin is cast about the conductor in such a way as to provide the required vacuum tight seal. The technique by which this is accomplished is reviewed. Equally important is the elimination of voids in the epoxy which will act as stress-concentrating discontinuities during cooling to or warming from 4K. The types of voids that could be expected and their causes are described. The paper reviews techniques employed to eliminate voids within the cast-resin portion of the bushing

Isothermal relaxation current and microstructure changes of thermally aged polyester films impregnated by epoxy resin

Science.gov (United States)

Jiang, Xiongwei; Sun, Potao; Peng, Qingjun; Sima, Wenxia

2018-01-01

In this study, to understand the effect of thermal aging on polymer films degradation, specimens of polyester films impregnated by epoxy resin with different thermal aging temperatures (80 and 130 °C) and aging times (500, 1600, 2400 and 3000 h) are prepared, then charge de-trapping properties of specimens are investigated via the isothermal relaxation current (IRC) measurement, the distributions of trap level and its corresponding density are obtained based on the modified IRC model. It is found that the deep trap density increases remarkably at the beginning of thermal aging (before 1600 h), but it decreases obviously as the aging degree increases. At elevated aging temperature and, in particular considering the presence of air gap between two-layer insulation, the peak densities of deep traps decrease more significant in the late period of aging. It can be concluded that it is the released energy from de-trapping process leads to the fast degradation of insulation. Moreover, after thermal aging, the microstructure changes of crystallinity and molecular structures are analyzed via the x-ray diffraction experiment and Fourier transform infrared spectrometer. The results indicate that the variation of the deep trap density is closely linked with the changes of microstructure, a larger interface of crystalline/amorphous phase, more defects and broken chains caused by thermal aging form higher deep trap density stored in the samples.

Highly radiation-resistant vacuum impregnation resin systems for fusion magnet insulation

International Nuclear Information System (INIS)

Fabian, P.E.; Munshi, N.A.; Denis, R.J.

2002-01-01

Magnets built for fusion devices such as the newly proposed Fusion Ignition Research Experiment (FIRE) need to be highly reliable, especially in a high radiation environment. Insulation materials are often the weak link in the design of superconducting magnets due to their sensitivity to high radiation doses, embrittlement at cryogenic temperatures, and the limitations on their fabricability. An insulation system capable of being vacuum impregnated with desirable properties such as a long pot-life, high strength, and excellent electrical integrity and which also provides high resistance to radiation would greatly improve magnet performance and reduce the manufacturing costs. A new class of insulation materials has been developed utilizing cyanate ester chemistries combined with other known radiation-resistant resins, such as bismaleimides and polyimides. These materials have been shown to meet the demanding requirements of the next generation of devices, such as FIRE. Post-irradiation testing to levels that exceed those required for FIRE showed no degradation in mechanical properties. In addition, the cyanate ester-based systems showed excellent performance at cryogenic temperatures and possess a wide range of processing variables, which will enable cost-effective fabrication of new magnets. This paper details the processing parameters, mechanical properties at 76 K and 4 K, as well as post-irradiation testing to dose levels surpassing 10 8 Gy

Impregnation of bio-oil from small diameter pine into wood for moisture resistance

Science.gov (United States)

Thomas J. Robinson; Brian K. Via; Oladiran Fasina; Sushil Adhikari; Emily Carter

2011-01-01

Wood pyrolysis oil consists of hundreds of complex compounds, many of which are phenolic-based and exhibit hydrophobic properties. Southern yellow pine was impregnated with a pyrolysis oil-based penetrant using both a high pressure and vacuum impregnation systems, with no significant differences in retention levels. Penetrant concentrations ranging from 5-50% pyrolysis...

DEGRADATION OF MAGNET EPOXY AT NSLS X-RAY RING.

Energy Technology Data Exchange (ETDEWEB)

HU,J.P.; ZHONG,Z.; HAAS,E.; HULBERT,S.; HUBBARD,R.

2004-05-24

Epoxy resin degradation was analyzed for NSLS X-ring magnets after two decades of 2.58-2.8 GeV continuous electron-beam operation, based on results obtained from thermoluminescent dosimeters irradiated along the NSLS ring and epoxy samples irradiated at the beamline target location. A Monte Carlo-based particle transport code, MCNP, was utilized to verify the dose from synchrotron radiation distributed along the axial- and transverse-direction in a ring model, which simulates the geometry of a ring quadrupole magnet and its central vacuum chamber downstream of the bending-magnet photon ports. The actual life expectancy of thoroughly vacuum baked-and-cured epoxy resin was estimated from radiation tests on similar polymeric materials using a radiation source developed for electrical insulation and mechanical structure studies.

Evaluation of impact strength of epoxy based hybrid composites reinforced with e-glass/kevlar 49

International Nuclear Information System (INIS)

Jogi, S.A.; Memon, I.A.; Baloch, M.; Chandio, A.D.

2017-01-01

In hybridization different fibers are stacked layer by layer to produce laminates have specific strength and stiffness and employed in light weight high strength applications. Physically mean fabricated hybrid composites used in aerospace, under water, body armors and armed forces establishment. In present work drop-weight impact response of hybrid composites were investigated by making laminates of hybrid composites. In Hybridization layers of E-glass (roving) and Kevlar 49 fabrics stacked with epoxy resin. The layers formulation was set up by hand layup method. Impregnations of epoxy resin of commercial grade (601A) in fabrics were accomplished by VRTM (Vacuum Bagging Resin Transfer Molding) technique. Layup placementof Glass fibers/ Kevlar at 0 degree/90 degree, 45 degree/45 degree and 30 degree/60 degree were set for this work. Mechanical properties such as impact strength, bear resistance and break resistance were analyzed by using ASTM D-256 and D-3763 standard. Experimental investigation was conducted using instrumented Dart impact and Izod Impact test. E-glass/Kevlar 49 at layup 0 degree/90 degree and 30 degree/60 degree exhibited improvedimpact strength than 45 degree/45 degree. The surface morphology and fractography were also investigated by capturing different images of Specimens by using the SEM (Scanning Electron Microscopy). The fiberreinforcement and matrix fracture were also observed by using SEM.The SEM images suggest that epoxy resin tightly bonded with Kevlar fibers whereas Glass fibers were pulled out from laminations. (author)

Investigation of the metabolic consequences of impregnating spinach leaves with trehalose and applying a pulsed electric field.

Science.gov (United States)

Dymek, Katarzyna; Panarese, Valentina; Herremans, Els; Cantre, Dennis; Schoo, Rick; Toraño, Javier Sastre; Schluepmann, Henriette; Wadso, Lars; Verboven, Pieter; Nicolai, Bart M; Dejmek, Petr; Gómez Galindo, Federico

2016-12-01

The impregnation of leafy vegetables with cryoprotectants using a combination of vacuum impregnation (VI) and pulsed electric fields (PEF) has been proposed by our research group as a method of improving their freezing tolerance and consequently their general quality after thawing. In this study, we have investigated the metabolic consequences of the combination of these unit operations on spinach. The vacuum impregnated spinach leaves showed a drastic decrease in the porosity of the extracellular space. However, at maximum weight gain, randomly located air pockets remained, which may account for oxygen-consuming pathways in the cells being active after VI. The metabolic activity of the impregnated leaves showed a drastic increase that was further enhanced by the application of PEF to the impregnated tissue. Impregnating the leaves with trehalose by VI led to a significant accumulation of trehalose-6-phosphate (T6P), however, this was not further enhanced by PEF. It is suggested that the accumulation of T6P in the leaves may increase metabolic activity, and increase tissue resistance to abiotic stress. Copyright © 2016 Elsevier B.V. All rights reserved.

Salga de queijo tipo Minas por impregnação a vácuo Salting of Minas cheese by vacuum impregnation

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Luciana C. Hofmeister

2005-09-01

Full Text Available Estudou-se o uso da impregnação a vácuo (IV para a salga de queijo tipo Minas, utilizando-se uma câmara hermética, na qual amostras de queijos (cilíndricos, com massa de 500g e dimensões de 120mm de raio por 60mm de altura foram imersas em solução de salmoura com 22% em massa de NaCl. Os ensaios foram realizados após a etapa de enformagem e prensagem, para facilitar a reprodutibilidade estrutural dos queijos. Utilizou-se vácuo de 85,3kPa (Pabsoluta =16kPa, aplicado intermitentemente, intercalado com a recuperação da pressão atmosférica na câmara. Após períodos pré-estabelecidos, a câmara foi aberta e os queijos foram pesados e secionados, de modo a permitir a determinação da distribuição de sal no interior dos mesmos pelo método de Mohr. A salga por IV permitiu a obtenção de queijos com 1,6% em massa de sal em 15 minutos, contra 2,5 horas da salga convencional. Além disso, a distribuição de sal nos queijos salgados por IV foi mais homogênea do que nos queijos salgados por imersão em salmoura a pressão atmosférica. Esses resultados indicaram que a salga de queijos tipo Minas por IV pode ser uma boa alternativa de processamento, tanto do ponto de vista econômico como tecnológico.Minas cheese salting by vacuum impregnation was studied using cylindrical cheese samples of about 500 g and 120 ' 60mm (radius ' height, that were immersed in a hermetic chamber with 22g NaCl/100g, where sub-atmospheric pressures were applied. The essays were performed after the press stage, used in this to obtain more compact cheeses and facilitate the reproducibility of an average cheese pore structure. Vacuum intensity of 85.3kPa (absolute pressure of 16kPa was applied intermittently, interleaving with the atmospheric pressure recuperation in the chamber. After pre-determined periods, the chamber was opened and the cheeses were weighed and cut, in order to determine the salt concentration distributions, by means of a modified Mohr

Synthesis, structure and properties of novel epoxy and rubber-modified epoxy impregnated Y-Ba-Cu-O superconductors

International Nuclear Information System (INIS)

Low, I.M.; Lim, F.W.; Chisholm, W.

1992-01-01

This paper reports the synthesis, structure and properties of novel YBa 2 Cu 3 O 6+x (123) - polymer composites. The polymers used were epoxy and rubber-modified epoxy resins. Superconducting composites with good strength, toughness, hardness and chemical resistance have been successfully fabricated. The presence of polymer(s) does not appear to affect the superconducting (T c ) of about 90 K. Levitation experiments show that the height (z) of the levitating magnet depends on sample thickness, and mass and pole strength of the magnet. A simple image force model best describes the observed dependence of z on the mass and pole strength. Atomic absorption and pH measurements in the corrosion study show that the polymer coating provides an impermeable barrier to the ingress of solvents and a concomitant resistance to phase decomposition. 12 refs., 2 tabs., 5 figs

Substrate Effect on Carbon/Ceramic Mixed Matrix Membrane Prepared by a Vacuum-Assisted Method for Desalination

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Yingjun Song

2018-05-01

Full Text Available This work investigates the effect of various membrane substrates and coating conditions on the formation of carbon/ceramic mixed matrix membranes for desalination application. The substrates were impregnated with phenolic resin via a vacuum-assisted method followed by carbonization under an inert gas. Substrates with pore sizes of 100 nm required a single impregnation step only, where short vacuum times (<120 s resulted in low quality membranes with defects. For vacuum times of ≥120 s, high quality membranes with homogeneous impregnation were prepared leading to high salt rejection (>90% and high water fluxes (up to 25 L m−2 h−1. The increase in water flux as a function of the vacuum time confirms the vacuum etching effect resulting from the vacuum-assisted method. Substrates with pore sizes of 140 nm required two impregnation steps. These pores were too large for the ceramic inter-particle space to be filled with phenolic resin via a single step. In the second impregnation step, increasing the concentration of the phenolic resin resulted in membranes with lower water fluxes. These results indicate that thicker films were formed by increasing the phenolic resin concentration. In the case of substrates with pores of 600 nm, these pores were too large and inter-particle space filling with phenolic resin was not attained.

Development study of concrete reinforcement made of aramid fiber-reinforced plastic rods with high radiation resistance. 1. Epoxy resin compounds with a handling at room temperature impregnation

International Nuclear Information System (INIS)

Udagawa, Akira; Seguchi, Tadao; Moriya, Toshio; Matsubara, Sumiyuki; Hongou, Yoshihiko

1999-03-01

Aramid fiber-reinforced plastic (ArFRP) rods were developed in order to avoid from conduction current and/or magnetization of the metallic reinforcement using concrete constructions. For the polymer matrix, new epoxy resin compounds consist of tetraglycidyl diaminodiphenylmethane (30%), diglycidyl ether of bisphenol-A (60%), styrene oxide (10%) and aromatic diamine as a hardner were found to be the best formulation, and which were easily impregnated to the aramid fiber braiding yarn at room temperature. The ArFRP rods has a high radiation resistance, and the tensile strength was maintained to 98% (1.45 GPa) after irradiation dose of 100 MGy (absorbed energy MJ/kg), which is available for the reinforcement of concrete construction for the house of fusion reactor with super conducting magnets. (author)

Surface modification of epoxy resin using He/CF{sub 4} atmospheric pressure plasma jet for flashover withstanding characteristics improvement in vacuum

Energy Technology Data Exchange (ETDEWEB)

Chen, Sile; Wang, Shuai; Wang, Yibo; Guo, Baohong; Li, Guoqiang; Chang, Zhengshi; Zhang, Guan-Jun, E-mail: gjzhang@xjtu.edu.cn

2017-08-31

Highlights: • Epoxy resin (EP) samples are treated by atmospheric pressures plasma jet (APPJ). • Flashover withstanding characteristics of epoxy resin samples are improved a lot after APPJ treatment. • Appropriate treatment conditions are important to modify EP samples by APPJ. • Both physical and chemical effects lead to the enhancement of flashover strength. - Abstract: For enhancing the surface electric withstanding strength of insulating materials, epoxy resin (EP) samples are treated by atmospheric pressure plasma jet (APPJ) with different time interval from 0 to 300s. Helium (He) and tetrafluoromethane (CF{sub 4}) mixtures are used as working gases with the concentration of CF{sub 4} ranging 0%-5%, and when CF{sub 4} is ∼3%, the APPJ exhibits an optimal steady state. The flashover withstanding characteristics of modified EP in vacuum are greatly improved under appropriate APPJ treatment conditions. The surface properties of EP samples are evaluated by surface roughness, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. It is considered that both physical and chemical effects lead to the enhancement of flashover strength. The physical effect is reflected in the increase of surface roughness, while the chemical effect is reflected in the graft of fluorine groups.

Laser incising of wood: Impregnation of columns with water-soluble dye

International Nuclear Information System (INIS)

Hattori, N.; Ando, K.; Kitayama, S.; Nakamura, Y.

1994-01-01

To know whether or not laser incising is a useful pre-treatment technique in impregnating a chemical fluid into lumber, pin holes were made in columns of hinoki (Chamaecyparis obtusa Endl.), sugi (Cryptomeria japonica D. Don), karamatsu (Larix leptolepis Gordon) and douglas-fir (Pseudo-tsuga menziesii Franco) with 1.7 kW CO2 laser, and a water-soluble dye was impregnated into these columns with a local pressure impregnation device. Retentions, and lengths and widths of penetrations from each hole were measured quantitatively. Referring to the results of the preparatory experiment mentioned above, incising patterns for sugi and douglas-fir were designed, and the same water-soluble dye was impregnated into the laser-incised columns as well as into non-incised ones with the vacuum-pressure method to obtain penetrated layers with the target depths completely. As a result, a retention of 200 kg/m3 of dye could be achieved for a column of douglas-fir even if it is a species difficult to impregnate. The penetrated layer also could be formed completely at the depth of the laser incision. Therefore, it is concluded that laser incising can be used for the pre-treatment before impregnation of wood columns. (author)

Epoxy resin casting of trim coils for superconducting cyclotron

International Nuclear Information System (INIS)

Hajra, D.P.; Sarkar, S.C.; Saha, Subimal; Chaudhuri, J.; Bhandari, R.K.

2006-01-01

The life of any magnet depends on the soundness of the coil insulation, its aging properties and initial and final endurance limitations. The insulation of water-cooled trim coils for superconducting cyclotron is made of glass fibre tape with heat cured unfilled epoxy resin combination. This type of insulation has been selected to achieve excellent stability against thermal and electromagnetic stresses, tight dimensional control, good dielectric strength, non-hygroscopic and considerably low vapour-pressure as it will be inside rough vacuum. The process development and the difficulties encountered for appropriate selection of epoxy resin combination, potting, vacuum process, curing cycle, control of coil dimension to achieve a sound coil absolutely free from cracks, trapped air and voids has been discussed. (author)

Flexural Strength of Banana Fibre Reinforced Epoxy Composites Produced through Vacuum Infusion and Hand Lay-Up Techniques - A Comparative Study

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Mohamed Rahman

2017-07-01

Full Text Available Natural fiber such as kenaf, sisal, pineapple leaf and banana are growing popular nowadays due to its favor over traditional glass fiber and inorganic material. It is a renewable resources and abundantly available in the market. The composites made of natural fiber are economical, lightweight and environmental friendly. This study works on producing a composite based on the Banana fiber reinforced epoxy resin by using the method of Vacuum Infusion and Hand Lay-up. Banana fiber will be treated with Sodium Hydroxide (NaOH and water solution for 1 hour and then dried in the oven for 24 hours at 100°C. The composite will be produce based on different fiber volume fraction of 20% and 40% as well as different fiber length of 127mm, and 63mm. In Vacuum Infusion process, a mold made of aluminium have been manufactured according to the size of specimens of 127mm x 12.7mm x 3.2mm in dimension will be used in the preparation of specimens. The specimens of different volume fraction and fiber length produced by vacuum infusion and hand lay-up method will be mechanically tested through flexural test. The highest flexural strength is the specimen made by vacuum infusion process with 40% volume fraction and 63mm fiber length, which is 136.27MPa while for the hand lay-up process, the highest flexural strength is 80.71 with 40% volume fraction and 63mm fiber length.

Effect of Thermally Reduced Graphene Oxide on Mechanical Properties of Woven Carbon Fiber/Epoxy Composite

OpenAIRE

Nitai Chandra Adak; Suman Chhetri; Naresh Chandra Murmu; Pranab Samanta; Tapas Kuila

2018-01-01

Thermally reduced graphene oxide (TRGO) was incorporated as a reinforcing filler in the epoxy resin to investigate the effect on the mechanical properties of carbon fiber (CF)/epoxy composites. At first, the epoxy matrix was modified by adding different wt % of TRGO from 0.05 to 0.4 wt % followed by the preparation of TRGO/CF/epoxy composites througha vacuum-assisted resin transfer molding process. The prepared TRGO was characterized by using Fourier transform infrared spectroscopy, Raman Spe...

Fabrication of the new poloidal field coils for DIII-D

International Nuclear Information System (INIS)

Heiberger, M.; Bott, R.J.; Gallix, R.; Street, R.W.

1986-01-01

The six new poloidal field coil assemblies manufactured by GA Technologies (GA) for DIII-D range in diameter from 3.4-5.3 m. Two of them are 55-turn field shaping coils. Each of the other four combines one turn of the ohmic heating coil and a 55-turn field shaping coil into a single unit encased in a stainless steel box beam. These four box beams, which provide support for the coils inside, are part of the overall coil and vacuum vessel support structure. They also serve as molds for vacuum impregnating the coils with epoxy. All coils are made of hollow, water-cooled copper conductor. The larger field shaping coils are designed for 20 kA, 3 sec rectangular current pulses with 40 0 C temperature rise. The ohmic heating coil turns are capable of currents of up to 110 kA. The conductor is wrapped with Kapton and fiberglass tape; Kapton provides 1000 V/turn and 28 kV coil-to-ground insulation. The fiberglass acts as wick and reinforcement for the vacuum impregnated epoxy resin which bonds the coil together. The fabrication process is described in detail and illustrated. Tools and setups used for special operations such as induction brazing, conductor winding, conductor bending, and vacuum impregnation are presented. The quality control procedures followed to guarantee sound brazed joints are explained. The electrical tests performed at several stages of fabrication, especially the 1000 V/turn impulse tests conducted before potting to facilitate fault detection and repair, are described

Occupational contact dermatitis caused by aniline epoxy resins in the aircraft industry.

Science.gov (United States)

Pesonen, Maria; Suuronen, Katri; Jolanki, Riitta; Aalto-Korte, Kristiina; Kuuliala, Outi; Henriks-Eckerman, Maj-Len; Valtanen, Ilona; Alanko, Kristiina

2015-08-01

Tetraglycidyl-4,4'-methylenedianiline (TGMDA) is an aniline epoxy resin used in, for example, resin systems of pre-impregnated composite materials (prepregs) of the aircraft industry. Allergic contact dermatitis caused by TGMDA in prepregs has been described previously. To report on 9 patients with occupational allergic contact dermatitis caused by TGMDA in epoxy glues used in helicopter assembly. The patients were examined with patch testing at the Finnish Institute of Occupational Health in 2004-2009. The first patient was diagnosed by testing both components of two epoxy glues from the workplace, and was also tested with glue ingredients, including TGMDA. The following patients were tested with the glues and TGMDA. The resin parts of the glues were analysed for their epoxy compounds, including TGMDA. All of the patients had a patch test reaction to one or both of the resin parts of the TGMDA-containing glues. Eight of them had a strong allergic reaction to TGMDA, and one had a doubtful reaction to TGMDA. Two of the patients also had an allergic reaction to triglycidyl-p-aminophenol (TGPAP), another aniline epoxy resin, which was not present in the TGMDA-containing glues. In aircraft industry workers with suspected occupational dermatitis, aniline epoxy resins should be considered and patch tested as possible contact allergens. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Thermoplastic impact property improvement in hybrid natural fibre epoxy composite bumper beam

International Nuclear Information System (INIS)

Davoodi, M M; Sapuan, S M; Ali, Aidy; Ahmad, D; Khalina, A

2010-01-01

Utilization of thermoset resin as a bumper beam composite matrix is currently more dominated in car manufacturer suppliers, because of availability, easy processing, low material cost and production equipment investment. Moreover, low viscosity, shrinkage and excellent flow facilitate better fibre impregnation and proper surface resin wetting. Three-dimensional cross linking curing increase impact, creep and environmental stress cracking resistance properties. Low impact properties of natural fibre epoxy composite, are main issues in its employment for automotive structural components. Impact properties in epoxy composite bumper beam could be increased by modifying the resin, reinforcement and manufacturing process as well as geometry parameters such as cross section, thickness, added ribs and fixing method optimizations could strengthen impact resistance. There are two main methods, flexibilisation and toughening, as modifying the resin in order to improve the impact properties of epoxy composite, which form single phase or two-phase morphology to make modifier as epoxy or from separate phase to keep the thermo-mechanical properties. Liquid rubber, thermoplastic, core shell particle and rigid particle are different methods of toughening improvements. In this research, thermoplastic toughening has used to improve impact properties in hybrid natural fibre epoxy composite for automotive bumper beam and has achieved reasonable impact improvements.

Tensile Mechanical Property of Oil Palm Empty Fruit Bunch Fiber Reinforced Epoxy Composites

Science.gov (United States)

Ghazilan, A. L. Ahmad; Mokhtar, H.; Shaik Dawood, M. S. I.; Aminanda, Y.; Ali, J. S. Mohamed

2017-03-01

Natural, short, untreated and randomly oriented oil palm empty fruit bunch fiber reinforced epoxy composites were manufactured using vacuum bagging technique with 20% fiber volume composition. The performance of the composite was evaluated as an alternative to synthetic or conventional reinforced composites. Tensile properties such as tensile strength, modulus of elasticity and Poisson’s ratio were compared to the tensile properties of pure epoxy obtained via tensile tests as per ASTM D 638 specifications using Universal Testing Machine INSTRON 5582. The tensile properties of oil palm empty fruit bunch fiber reinforced epoxy composites were lower compared to plain epoxy structure with the decrement in performances of 38% for modulus of elasticity and 61% for tensile strength.

Seawater Durability of Nano-Montmorillonite Modified Single-Lap Joining Epoxy Composite Laminates

OpenAIRE

ULUS, Hasan; KAYBAL, Halil Burak; DEMİR, Okan; TATAR, Ahmet Caner; SENYURT, Muhammed Ali; AVCI, Ahmet

2018-01-01

The objective of this study was to investigate of nano-montmorillonite modified epoxy composite single-lap bonded joints, after being exposed to seawater immersion in order to understand the effect of seawater environment on their performance. To prepare the nano adhesives, nano montmorillonite (2 wt %) was incorporated into epoxy resin. Composite bonded specimens which manufactured with VARIM (Vacuum Assisted Resin Infusion Method) were prepared accordance with ASTM D5868-01 and immersed in ...

Effects of alumina nanoparticles on dynamic impact responses of carbon fiber reinforced epoxy matrix nanocomposites

OpenAIRE

Halil B. Kaybal; Hasan Ulus; Okan Demir; Ömer S. Şahin; Ahmet Avcı

2018-01-01

The influence of alumina (Al2O3) nanoparticles addition upon low-velocity impact behaviors of carbon fiber (CF) reinforced laminated epoxy nanocomposites have been investigated. For this purpose, different amounts of Al2O3 nanoparticles ranging from 1 to 5 wt% were added to the epoxy resin in order to observe the effect of nanoparticle loadings. CF reinforced epoxy based laminated nanocomposites were produced using Vacuum Assisted Resin Infusion Method (VARIM). The low velocity impact (LVI) t...

Mechanical Properties of Epoxy and Its Carbon Fiber Composites Modified by Nanoparticles

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Fang Liu

2017-01-01

Full Text Available Compressive properties are commonly weak parts in structural application of fiber composites. Matrix modification may provide an effective way to improve compressive performance of the composites. In this work, the compressive property of epoxies (usually as matrices of fiber composites modified by different types of nanoparticles was firstly investigated for the following study on the compressive property of carbon fiber reinforced epoxy composites. Carbon fiber/epoxy composites were fabricated by vacuum assisted resin infusion molding (VARIM technique using stitched unidirectional carbon fabrics, with the matrices modified with nanosilica, halloysite, and liquid rubber. Testing results showed that the effect of different particle contents on the compressive property of fiber/epoxy composites was more obvious than that in epoxies. Both the compressive and flexural results showed that rigid nanoparticles (nanosilica and halloysite have evident strengthening effects on the compression and flexural responses of the carbon fiber composite laminates fabricated from fabrics.

CHEMISORPtION OF SULFUR (IV OXIDeBY PoLYETHYLENEPOLYAMINE IMPREGNATED FIBROUS MATERIALS. 1. HYDROPHILIC POLYETHYLENEPOLYAMINE IMPREGNATED FIBROUS MATERIALS

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A. A. Ennan

2015-03-01

Full Text Available The hydrophilicity of artificial and synthetic fibers and polyethylenepolyamine (PEPA impregnated fibrous materials based on them was investigated under static conditions using a vacuum sorption installation. Water vapor sorption isotherms were analyzed and monolayer capacitance values  and a water molecules adsorption in the first layer heats were determined in the framework of polymolecular adsorption Brunauer – Emmett – Teller. It has been found that the hydrophilicity of the fibers studied to change in the following sequence: viscose > VION AN-3 > VION KN-1 > nylon-polyester > nitrone > polyester > polypropylene; PEPA modified hydrophilic fibrous material does not depend essentially on the chemical nature of the carrier.

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene.

Science.gov (United States)

Naveh, Naum; Shepelev, Olga; Kenig, Samuel

2017-01-01

Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called "stacked" graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

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Naum Naveh

2017-09-01

Full Text Available Impregnation of expandable graphite (EG after thermal treatment with an epoxy resin containing surface-active agents (SAAs enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG. This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

Effect of thermally reduced graphene oxide on dynamic mechanical properties of carbon fiber/epoxy composite

Science.gov (United States)

Adak, Nitai Chandra; Chhetri, Suman; Murmu, Naresh Chandra; Samanta, Pranab; Kuila, Tapas

2018-03-01

The Carbon fiber (CF)/epoxy composites are being used in the automotive and aerospace industries owing to their high specific mechanical strength to weight ratio compared to the other conventional metal and alloys. However, the low interfacial adhesion between fiber and polymer matrix results the inter-laminar fracture of the composites. Effects of different carbonaceous nanomaterials i.e., carbon nanotubes (CNT), graphene nanosheets (GNPs), graphene oxide (GO) etc. on the static mechanical properties of the composites were investigated in detail. Only a few works focused on the improvement of the dynamic mechanical of the CF/epoxy composites. Herein, the effect of thermally reduced grapheme oxide (TRGO) on the dynamic mechanical properties of the CF/epoxy composites was investigated. At first, GO was synthesized using modified Hummers method and then reduced the synthesized GO inside a vacuum oven at 800 °C for 5 min. The prepared TRGO was dispersed in the epoxy resin to modify the epoxy matrix. Then, a number of TRGO/CF/epoxy laminates were manufactured incorporating different wt% of TRGO by vacuum assisted resin transfer molding (VARTM) technique. The developed laminates were cured at room temperature for 24 h and then post cured at 120 °C for 2 h. The dynamic mechanical analyzer (DMA 8000 Perkin Elmer) was used to examine the dynamic mechanical properties of the TRGO/CF/epoxy composites according to ASTM D7028. The dimension of the specimen was 44×10×2.4 mm3 for the DMA test. This test was carried out under flexural loading mode (duel cantilever) at a frequency of 1 Hz and amplitude of 50 μm. The temperature was ramped from 30 to 200 °C with a heating rate of 5 °C min-1. The dynamic mechanical analysis of the 0.2 wt% TRGO incorporated CF/epoxy composites showed ~ 96% enhancement in storage modulus and ~ 12 °C increments in glass transition temperature (Tg) compared to the base CF/epoxy composites. The fiber-matrix interaction was studied by Cole

Static and Dynamic Mechanical Properties of Graphene Oxide-Incorporated Woven Carbon Fiber/Epoxy Composite

Science.gov (United States)

Adak, Nitai Chandra; Chhetri, Suman; Kim, Nam Hoon; Murmu, Naresh Chandra; Samanta, Pranab; Kuila, Tapas

2018-03-01

This study investigates the synergistic effects of graphene oxide (GO) on the woven carbon fiber (CF)-reinforced epoxy composites. The GO nanofiller was incorporated into the epoxy resin with variations in the content, and the CF/epoxy composites were manufactured using a vacuum-assisted resin transfer molding process and then cured at 70 and 120 °C. An analysis of the mechanical properties of the GO (0.2 wt.%)/CF/epoxy composites showed an improvement in the tensile strength, Young's modulus, toughness, flexural strength and flexural modulus by 34, 20, 83, 55 and 31%, respectively, when compared to the CF/epoxy composite. The dynamic mechanical analysis of the composites exhibited an enhancement of 56, 114 and 22% in the storage modulus, loss modulus and damping capacity (tan δ), respectively, at its glass transition temperature. The fiber-matrix interaction was studied using a Cole-Cole plot analysis.

Surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet for flashover withstanding characteristics improvement in vacuum

Science.gov (United States)

Chen, Sile; Wang, Shuai; Wang, Yibo; Guo, Baohong; Li, Guoqiang; Chang, Zhengshi; Zhang, Guan-Jun

2017-08-01

For enhancing the surface electric withstanding strength of insulating materials, epoxy resin (EP) samples are treated by atmospheric pressure plasma jet (APPJ) with different time interval from 0 to 300s. Helium (He) and tetrafluoromethane (CF4) mixtures are used as working gases with the concentration of CF4 ranging 0%-5%, and when CF4 is ∼3%, the APPJ exhibits an optimal steady state. The flashover withstanding characteristics of modified EP in vacuum are greatly improved under appropriate APPJ treatment conditions. The surface properties of EP samples are evaluated by surface roughness, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. It is considered that both physical and chemical effects lead to the enhancement of flashover strength. The physical effect is reflected in the increase of surface roughness, while the chemical effect is reflected in the graft of fluorine groups.

Comparison of tensile strength of different carbon fabric reinforced epoxy composites

Directory of Open Access Journals (Sweden)

Jane Maria Faulstich de Paiva

2006-03-01

Full Text Available Carbon fabric/epoxy composites are materials used in aeronautical industry to manufacture several components as flaps, aileron, landing-gear doors and others. To evaluate these materials become important to know their mechanical properties, for example, the tensile strength. Tensile tests are usually performed in aeronautical industry to determinate tensile property data for material specifications, quality assurance and structural analysis. For this work, it was manufactured four different laminate families (F155/PW, F155/HS, F584/PW and F584/HS using pre-impregnated materials (prepregs based on F155TM and F584TM epoxy resins reinforced with carbon fiber fabric styles Plain Weave (PW and Eight Harness Satin (8HS. The matrix F155TM code is an epoxy resin type DGEBA (diglycidil ether of bisphenol A that contains a curing agent and the F584TM code is a modified epoxy resin type. The laminates were obtained by handing lay-up process following an appropriate curing cycle in autoclave. The samples were evaluated by tensile tests according to the ASTM D3039. The F584/PW laminates presented the highest values of tensile strength. However, the highest modulus results were determined for the 8HS composite laminates. The correlation of these results emphasizes the importance of the adequate combination of the polymeric matrix and the reinforcement arrangement in the structural composite manufacture. The microscopic analyses of the tested specimens show valid failure modes for composites used in aeronautical industry.

Novel Diels-Alder based self-healing epoxies for aerospace composites

Science.gov (United States)

Coope, T. S.; Turkenburg, D. H.; Fischer, H. R.; Luterbacher, R.; van Bracht, H.; Bond, I. P.

2016-08-01

Epoxy resins containing Diels-Alder (DA) furan and maleimide moieties are presented with the capability to self-heal after exposure to an external heat source. A conventional epoxy amine system has been combined with furfuryl and maleimide functional groups in a two-step process, to avoid major side-reactions, and the concentration of a thermo-reversibly binding cross-linker was considered to balance thermoset and thermoplastic behaviours, and the subsequent self-healing performance. In the context of self-repair technologies an inbuilt ‘intrinsic’ self-healing system is deemed favourable as the healing agent can be placed in known ‘hot spot’ regions (i.e. skin-stringer run outs, ply drops and around drilled holes) where operational damage predominately occurs in load bearing aerospace structures. In this study, the mechanical and self-healing performance of furan functionalised epoxy resins containing varying amounts (10, 20, 30 or 40 pph) of bismaleimide were investigated using a bulk epoxy polymer tapered double cantilever beam test specimen geometry. Two forms, a thin film and a bulk material, were evaluated to account for future integration methods into fibre reinforced polymer (FRP) composites. The highest healing efficiency, with respect to the obtained initial load value, was observed from the 20 pph bulk material derivative. The polymers were successful in achieving consistent multiple (three) healing cycles when heated at 150 °C for 5 min. This novel investigated DA material exhibits favourable processing characteristics for FRP composites as preliminary studies have shown successful coextrution with reinforcing fibres to form free standing films and dry fibre impregnation.

Effect of Thermally Reduced Graphene Oxide on Mechanical Properties of Woven Carbon Fiber/Epoxy Composite

Directory of Open Access Journals (Sweden)

Nitai Chandra Adak

2018-02-01

Full Text Available Thermally reduced graphene oxide (TRGO was incorporated as a reinforcing filler in the epoxy resin to investigate the effect on the mechanical properties of carbon fiber (CF/epoxy composites. At first, the epoxy matrix was modified by adding different wt % of TRGO from 0.05 to 0.4 wt % followed by the preparation of TRGO/CF/epoxy composites througha vacuum-assisted resin transfer molding process. The prepared TRGO was characterized by using Fourier transform infrared spectroscopy, Raman Spectroscopy and field emission scanning electron microscopy (FE-SEM techniques. It was observed that the wrinkled structure of synthesized TRGO may be helpful to interlock with the epoxy resin and CF.The inter-laminar shear strength, in-plane fracture toughness and impact strength increased by ~67%, 62% and 93% at 0.2 wt % of TRGO loading in the CF/epoxy composites as compared to the CF reinforced epoxy. The mechanical properties of the hybrid composites decreased beyond the 0.2 wt % of TRGO incorporation in the epoxy resin. The fracture surfaces of the hybrid composites were studied by FE-SEM image analysis to investigate the synergistic effect of TRGO in the CF/epoxy composite. This study suggested that TRGO could be used asgood nanofiller to resist the matrix and fiber fracture.

Mass impregnation plant speeds high voltage cable production

Energy Technology Data Exchange (ETDEWEB)

1965-05-07

A mass impregnation and continuous sheath extrusion plant that will eliminate the long period of vacuum treatment usually required for high voltage oil-filled cables is among the latest techniques included in the new factory at Pirelli General's Eastleigh works. The new factory is said to be the first in Europe designed solely for the manufacture of the full range of oil-filled cables. Possible future increases of system voltages to about 750-kV ac or 1000-kV dc have been taken into account in the design of the works, so that only a small amount of modification and new plant will be involved.

What is Common in the Training of the Large Variety of Impregnated Corrector Magnets for the LHC

CERN Document Server

Ijspeert, Albert

2004-01-01

The Large Hadron Collider (LHC) will be equipped with about 5000 superconducting corrector magnets of 10 different types, ranging from dipoles through quadrupoles, sextupoles and octupoles to decapoles and dodecapoles. Four wires are used with 2 copper/superconductor ratios. Magnet lengths range from 0.15 m to 1.4 m. However, the magnets are all epoxy-impregnated and wound with enameled monolithic wires. The paper highlights the features that are common in the training of all these different magnets and uses that to give some clues for the possible origin of the training.

Simultaneous acoustic and dielectric real time curing monitoring of epoxy systems

Science.gov (United States)

Gkikas, G.; Saganas, Ch.; Grammatikos, S. A.; Aggelis, D. G.; Paipetis, A. S.

2012-04-01

The attainment of structural integrity of the reinforcing matrix in composite materials is of primary importance for the final properties of the composite structure. The detailed monitoring of the curing process on the other hand is paramount (i) in defining the optimal conditions for the impregnation of the reinforcement by the matrix (ii) in limiting the effects of the exotherm produced by the polymerization reaction which create unwanted thermal stresses and (iii) in securing optimal behavior in matrix controlled properties, such as off axis or shear properties and in general the durability of the composite. Dielectric curing monitoring is a well known technique for distinguishing between the different stages of the polymerization of a typical epoxy system. The technique successfully predicts the gelation and the vitrification of the epoxy and has been extended for the monitoring of prepregs. Recent work has shown that distinct changes in the properties of the propagated sound in the epoxy which undergoes polymerization is as well directly related to the gelation and vitrification of the resin, as well as to the attainment of the final properties of the resin system. In this work, a typical epoxy is simultaneously monitored using acoustic and dielectric methods. The system is isothermally cured in an oven to avoid effects from the polymerization exotherm. Typical broadband sensors are employed for the acoustic monitoring, while flat interdigital sensors are employed for the dielectric scans. All stages of the polymerization process were successfully monitored and the validity of both methods was cross checked and verified.

Thermally induced self-healing epoxy/glass laminates with porous layers containing crystallized healing agent

Directory of Open Access Journals (Sweden)

T. Szmechtyk

2018-07-01

Full Text Available Porous glass fiber and paper layers were tested for application in thermally induced self healing epoxy laminates as healing porous layers. Both types of layers were impregnated using high purity bisphenol A diglycidyl ether (BADGE epoxy with ability to crystallize during storage under 25 °C. Absorption capacity of porous layers was evaluated. Differential scanning calorimetry was used to investigate BADGE healing agent recrystallization process. Healing porous glass layers (HPGL were selected for further tests. Liquid chromatography and Fourier transform infrared (FT IR spectroscopy provided information about average molecular mass of embedded healing agent and functional groups in HPGL layers. Self-healing efficiency of three different laminates with HPGL layers was calculated based on the results of three-point bending test and Charpy impact test. Also, flexural properties and impact strength of laminates were evaluated. The obtained results confirm competitive self healing ability of composites with HPGL.

Mechanical performance of carbon-epoxy laminates. Part II: quasi-static and fatigue tensile properties

Directory of Open Access Journals (Sweden)

José Ricardo Tarpani

2006-06-01

Full Text Available In Part II of this work, quasi-static tensile properties of four aeronautical grade carbon-epoxy composite laminates, in both the as-received and pre-fatigued states, have been determined and compared. Quasi-static mechanical properties assessed were tensile strength and stiffness, tenacity (toughness at the maximum load and for a 50% load drop-off. In general, as-molded unidirectional cross-ply carbon fiber (tape reinforcements impregnated with either standard or rubber-toughened epoxy resin exhibited the maximum performance. The materials also displayed a significant tenacification (toughening after exposed to cyclic loading, resulting from the increased stress (the so-called wear-in phenomenon and/or strain at the maximum load capacity of the specimens. With no exceptions, two-dimensional woven textile (fabric pre-forms fractured catastrophically under identical cyclic loading conditions imposed to the fiber tape architecture, thus preventing their residual properties from being determined.

Note: Ultra-low birefringence dodecagonal vacuum glass cell

Energy Technology Data Exchange (ETDEWEB)

Brakhane, Stefan, E-mail: brakhane@iap.uni-bonn.de; Alt, Wolfgang; Meschede, Dieter; Robens, Carsten; Moon, Geol; Alberti, Andrea [Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, D-53115 Bonn (Germany)

2015-12-15

We report on an ultra-low birefringence dodecagonal glass cell for ultra-high vacuum applications. The epoxy-bonded trapezoidal windows of the cell are made of SF57 glass, which exhibits a very low stress-induced birefringence. We characterize the birefringence Δn of each window with the cell under vacuum conditions, obtaining values around 10{sup −8}. After baking the cell at 150 °C, we reach a pressure below 10{sup −10} mbar. In addition, each window is antireflection coated on both sides, which is highly desirable for quantum optics experiments and precision measurements.

Direct measurement of elastic modulus of Nb 3Sn using extracted filaments from superconducting composite wire and resin impregnation method

Science.gov (United States)

Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.

2006-10-01

Young's modulus of Nb3Sn filaments in Nb3Sn/Cu superconducting composite wire was investigated in detail. Nb3Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb3Sn/Nb barrier and bronze. Then, Nb3Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb3Sn filament modulus. The ratio of Nb3Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb3Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values.

Direct measurement of elastic modulus of Nb3Sn using extracted filaments from superconducting composite wire and resin impregnation method

International Nuclear Information System (INIS)

Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.

2006-01-01

Young's modulus of Nb 3 Sn filaments in Nb 3 Sn/Cu superconducting composite wire was investigated in detail. Nb 3 Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb 3 Sn/Nb barrier and bronze. Then, Nb 3 Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb 3 Sn filament modulus. The ratio of Nb 3 Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb 3 Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values

Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

Science.gov (United States)

Needles, H. L.

1985-01-01

The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

Mechanical performance of carbon-epoxy laminates. Part I: quasi-static and impact bending properties

Directory of Open Access Journals (Sweden)

José Ricardo Tarpani

2006-06-01

Full Text Available In Part I of this study, quasi-static and impact bending properties of four aeronautical grade carbon-epoxy laminates have been determined and compared. Materials tested were unidirectional cross-ply (tape and bidirectional woven textile (fabric carbon fiber lay-up architectures, impregnated with standard and rubber-toughened resins, respectively, giving rise to 1.5 mm-thick laminates. Quasi-static mechanical properties assessed in transversal mode loading were modulus of elasticity, flexural strength and tenacity at the maximum load, whereas the net absorbed energy was determined under translaminar impact conditions. Two-dimensional woven carbon fiber reinforcements embedded in a rubber-toughened matrix presented the best mechanical performance under static loading. Under dynamic loading conditions, woven fiber fabric pre-forms were favorably sensitive to increasing impact energies regardless the nature of the employed epoxy resin. However, it was concluded that great care should be taken with this material within the low energy impact regimen.

Effect of vacuum impregnation temperature on the mechanical properties and osmotic dehydration parameters of apples

Directory of Open Access Journals (Sweden)

Sabrina Silva Paes

2008-08-01

Full Text Available The effect of sucrose solution temperature on the mechanical properties, water loss (WL, solids gain (SG and weight reduction (WR of apples (Fuji var. treated by vacuum impregnation was studied. Temperatures were varied from 10 to 50 ºC, using a sucrose solution of 50 ºBrix. The mechanical properties were studied throughout a stress relaxation test. The results showed that the SG varied between 10.57 and 14.29 % and the WL varied between 10.55 and 14.48 %. The treated fruit soluble solids increased with the temperature probably due to the lower viscosity of the solution. The maximum stress was highest at 10 ºC, decreasing at higher temperatures, probably due the softening of the structure.A impregnação a vácuo (VI de alimentos é realizada pela aplicação de vácuo em um tanque contendo o produto imerso em uma solução, seguida da recuperação da pressão atmosférica. Neste trabalho, estudou-se o efeito da temperatura da solução de sacarose nas propriedades mecânicas das amostras e na perda de água (WL, ganho de sólidos (SG e redução de peso (WR. A faixa de temperaturas estudada foi de 10 a 50 ºC, usando uma solução de sacarose com 50 ºBrix. As propriedades mecânicas das amostras foram estudadas através de ensaios mecânicos de deformação-relaxação. O SG variou entre 10.57 e 14.29 %, enquanto WL variou entre 10.55 e 14.48 %. O teor de sólidos das frutas tratadas aumentou com a temperatura, provavelmente devido à diminuição da viscosidade da solução. A tensão máxima foi maior a 10 ºC, diminuindo com a temperatura, devido ao amolecimento da estrutura.

Vapor-Gas Bubble Evolution and Growth in Extremely Viscous Fluids Under Vacuum

Science.gov (United States)

Kizito, John; Balasubramaniam, R.; Nahra, Henry; Agui, Juan; Truong, Duc

2008-01-01

Formation of vapor and gas bubbles and voids is normal and expected in flow processes involving extremely viscous fluids in normal gravity. Practical examples of extremely viscous fluids are epoxy-like filler materials before the epoxy fluids cure to their permanent form to create a mechanical bond between two substrates. When these fluids flow with a free liquid interface exposed to vacuum, rapid bubble expansion process may ensue. Bubble expansion might compromise the mechanical bond strength. The potential sources for the origin of the gases might be incomplete out-gassing process prior to filler application; regasification due to seal leakage in the filler applicator; and/or volatiles evolved from cure reaction products formed in the hardening process. We embarked on a study that involved conducting laboratory experiments with imaging diagnostics in order to deduce the seriousness of bubbling caused by entrained air and volatile fluids under space vacuum and low gravity environment. We used clear fluids with the similar physical properties as the epoxy-like filler material to mimic the dynamics of bubbles. Another aspect of the present study was to determine the likelihood of bubbling resulting from dissolved gases nucleating from solution. These experimental studies of the bubble expansion are compared with predictions using a modified Rayleigh- Plesset equation, which models the bubble expansion.

Influence of MWCNTs addition on mechanical and thermal behaviour of epoxy/kenaf multi-scale nanocomposite

Science.gov (United States)

Noor, N. A. M.; Razak, J. A.; Ismail, S.; Mohamad, N.; Yaakob, M. Y.; Theng, T. H.

2017-06-01

This research was conducted to develop kenaf reinforced epoxy/MWCNTs multi-scale composite using kenaf fibre and MWCNTs as the reinforcement in epoxy as the hosted matrix. The composites were produced by using a combination of hand lay-up and vacuum bagging process. The selection of optimum composition of epoxy-MWCNTs is based on the MWCNTs loading and the resulted mixture viscosity. Lower resin viscosity is required to allow good wetting and interaction between matrix and filler, which will yielded superior final performance of the fabricated composites. Therefore, different loading of MWCNTs (0.0 wt. %, 0.5 wt. %, 1.0 wt. %, 3.0 wt. %, 5.0 wt. %, 7.0 wt. %) were used to investigate the mechanical and thermal properties of the composites. As a result, the epoxy/kenaf/MWCNTs multi-scale composite at 1.0 wt. % of MWCNTs addition had yielded substantial improvement by 15.54 % in tensile strength and 90.54 % in fracture toughness. Besides, the fracture surface morphology of the selected samples were analysed via scanning electron microscopy (SEM) observation to further support the reinforcement characteristic of epoxy/kenaf/MWCNTs multi-scale composite.

Comparison of the compressive strength of impregnated and nonimpregnated eucalyptus subjected to two different pressures and impregnation times

Directory of Open Access Journals (Sweden)

Waldemir Rodrigues

2004-06-01

Full Text Available The durability of wood is affected by several factors. For this reason, much research has been done on a variety of chemical compounds for impregnating wood, aimed at preserving it while simultaneously improving its properties. Recent studies of the properties of impregnated wood have demonstrated the possibility of substantially improving its mechanical characteristics. Thus, the purpose of this work was to compare the strength to parallel compression of wooden fibers (Eucalyptus grandis, both nonimpregnated and impregnated with a monocomponent resin, from the standpoint of pressure and impregnation time, aiming at its structural utilization. The results demonstrate that the compressive strength of impregnated test specimens is greater than that of nonimpregnated ones, indicating that monocomponent polyurethane resin can be considered suitable for impregnating wood, since it increases the compressive strength of eucalyptus.

Recycling of impregnated wood and impregnating agents - combustion plant technology; Kyllaestetyn puutavaran ja kyllaestysaineiden kierraetys - polttolaitostekniikka

Energy Technology Data Exchange (ETDEWEB)

Syrjaenen, T.; Kangas, E. [Kestopuu Oy, Helsinki (Finland)

2000-07-01

It has been estimated that in the 20th century it is possible to recycle about 70 000 m{sup 3} of impregnated wood, corresponding to about 48 % of the total amount of annually demolished impregnated wood. The amount is estimated to grow up to 130 000 m{sup 3} in 2015 (about 65% of demolished impregnated wood). In the beginning half of the recyclable impregnated wood is poles, but the share of sawn timber will increase as the time goes by. The poles and pieces of them are demolished and transported to an intermediate storage e.g. on the yard of an electricity supply company, from which they can be fetched in larger quantities. Even wood impregnation plant can act as intermediate storage sites. Collection points for impregnated construction timber can be established on timer sales companies, but most of it will be collected at waste processing sites. The economy of impregnated wood recycling chain depends on the sales income of generated energy. Calculations show that collection, transportation and processing costs can be covered with the sales of impregnated wood for energy generation and with recycling fees. The recycling fee for sawn timber would be 20 FIM/m{sup 3} and that for poles 64 FIM/m{sup 3}. In 2001 recycling fees were set for impregnated wood, the fees being 11 FIM/m{sup 3} for sawn timber and 42 FIM/m{sup 3} for poles. Collected impregnated wood can be crushed with either fixed or movable crushers used for crushing of waste wood. The impurities of wood (bolts, nails, stones, etc.), large dimensions of wood, in- homogenous material and dust require special features for the crushing equipment. Crushing device can be equipped with feeding crane and saw for processing of large-dimension wood, and metal detectors and magnetic separators if needed, but the large metal scrap has to be removed before crushing. At present in Finland there is not a combustion plant capable for combustion of impregnated wood without any modification. Improvements of flue gas

Development of high-mechanical strength electrical insulations for tokamak toroidal field coils

International Nuclear Information System (INIS)

Burke, C.

1977-01-01

The electrical insulation for the TF (Toroidal Field) coils is subjected to a high interlaminar shear, tensile and compressive stresses. Two candidate epoxy/glass fiber systems using prepreg and vacuum impregnation techniques were evaluated. Specimens were prepared and processed under controlled conditions to simulate specification manufacturing procedures. The strengths of the insulation were measured in interlaminar shear, tension, compression, and combined shear and compression statically. Shear modulus determinations were also made. Various techniques of surface treatments to increase bond strengths with three resin primers were tested

Tensile properties of interwoven hemp/PET (Polyethylene Terephthalate) epoxy hybrid composites

Science.gov (United States)

Ahmad, M. A. A.; Majid, M. S. A.; Ridzuan, M. J. M.; Firdaus, A. Z. A.; Amin, N. A. M.

2017-10-01

This paper describes the experimental investigation of the tensile properties of interwoven Hemp/PET hybrid composites. The effect of hybridization of hemp (warp) with PET fibres (weft) on tensile properties was of interest. Hemp and PET fibres were selected as the reinforcing material while epoxy resin was chosen as the matrix. The interwoven Hemp/PET fabric was used to produce hybrid composite using a vacuum infusion process. The tensile test was conducted using Universal Testing Machine in accordance to the ASTM D638. The tensile properties of the interwoven Hemp/PET hybrid composite were then compared with the neat woven hemp/epoxy composite. The results show that the strength of hemp/PET with the warp direction was increased by 8% compared to the neat woven hemp composite. This enhancement of tensile strength was due to the improved interlocking structure of interwoven Hemp/PET hybrid fabric.

Experimental Study of Impregnation Birch and Aspen Samples

Directory of Open Access Journals (Sweden)

Igor Vladislavovich Grigorev

2014-10-01

Full Text Available An experimental study of wood impregnation was implemented by applying centrifugal methods. The impregnants were a 10% aqueous solution of potassium chloride and a 2% aqueous solution of borax. Birch (Betula pendula and aspen (Populus tremula wood samples in different moisture content were tested. The impregnation time in the centrifugal device were 30 seconds repeated 21 times, and the samples were measured after every 30 seconds. The experimental results were fitted to a nonlinear filtration law, which indicated that the centrifugal wood impregnation was dependent on wood species, wood moisture, rotational speed, and radius. Determination of rotational speed and centrifuge radius for impregnating aspen and birch at varying lengths and humidity under conditions of the nonlinear impregnant filtration law can be done using the example charts that were developed and presented in this study.

Digital laminography assessment of the damage in concrete exposed to freezing temperatures

KAUST Repository

Wakimoto, Kentaro

2008-10-01

The research explores the possibility of using digital laminography as a non-destructive inspection X-ray method to image the damage existing in concrete exposed to low temperatures. Freezing-thawing and scaling tests were performed and digital laminography was used to determine the degree of damage existing inside the concrete samples. First, digital laminography was performed on the concrete sample and then a visual inspection was done by slicing the sample after it was vacuum-impregnated with epoxy in order to compare the differences in crack width. © 2008 Elsevier Ltd. All rights reserved.

Digital laminography assessment of the damage in concrete exposed to freezing temperatures

KAUST Repository

Wakimoto, Kentaro; Blunt, Joshua; Carlos, Cruz; Monteiro, Paulo J.M.; Ostertag, Claudia P.; Albert, Richard

2008-01-01

The research explores the possibility of using digital laminography as a non-destructive inspection X-ray method to image the damage existing in concrete exposed to low temperatures. Freezing-thawing and scaling tests were performed and digital laminography was used to determine the degree of damage existing inside the concrete samples. First, digital laminography was performed on the concrete sample and then a visual inspection was done by slicing the sample after it was vacuum-impregnated with epoxy in order to compare the differences in crack width. © 2008 Elsevier Ltd. All rights reserved.

Some properties of castor oil affecting its performance as a capacitor impregnant and their significance to future impregnant research

International Nuclear Information System (INIS)

Boicourt, G.P.

1975-01-01

For a considerable time castor oil and polychlorinated biphenyl (PCB) have been the principal impregnants used in energy-storage capacitors. Castor oil has proven to be better than PCB for pulsed applications. PCB's have come under attack as an environmental hazard, while castor oil is a vegetable product and its supply and quality are subject to fluctuation. These two facts make the development of new impregnants desirable. The properties of PCB as a capacitor impregnant are well known. This paper first compares a number of properties of castor oil and PCB's. A comparison is made between the lives of castor oil capacitors and comparable PCB energy-storage capacitors. Some of the physical and chemical properties of castor oil which make it a good pulse capacitor impregnant are examined. These properties can be used as a guide for future research on new pulse capacitor impregnants

Discharge behavior of vacuum arc ion source working in pulse mode

International Nuclear Information System (INIS)

Tang Pingying; Dai Jingyi; Tan Xiaohua; Jin Dazhi; Liu Tie; Ding Bonan

2005-01-01

Discharge behavior of the vacuum arc ion source working in pulse mode was investigated using high-speed photography and spectrum diagnosis. The evolvement of cathode spot on hydrogen-impregnated electrode was captured by high-speed photography, and the emission spectra of cathode spot at different pulse currents were analyzed. The experimental results show that in most cases, only one cathode spot can be found in the discharge zone of vacuum arc ion source, and the spot moves a little during the same discharge. Temperature of the cathode spot may rise while the discharge current increases, and ultimately the density of hydrogen ion will be increased. At the same time, sputtering of the electrode is enhanced and the quality of ion plasma will be reduced. (authors)

Mechanical Characterization and Water Absorption Behaviour of Interwoven Kenaf/PET Fibre Reinforced Epoxy Hybrid Composite

Directory of Open Access Journals (Sweden)

Yakubu Dan-mallam

2015-01-01

Full Text Available The development of interwoven fabric for composite production is a novel approach that can be adopted to address the challenges of balanced mechanical properties and water absorption behaviour of polymer composites. In this paper, kenaf and PET (polyethylene terephthalate fibre were selected as reinforcing materials to develop the woven fabric, and low viscosity epoxy resin was chosen as the matrix. Vacuum infusion process was adopted to produce the hybrid composite due to its superior advantages over hand lay-up technique. The weight percentage composition of the Epoxy/kenaf/PET hybrid composite was maintained at 70/15/15 and 60/20/20, respectively. A significant increase in tensile strength and elastic modulus of approximately 73% and 53% was recorded in relation to neat epoxy. Similarly, a substantial increase in flexural, impact, and interlaminar properties was also realized in relation to neat epoxy. This enhancement in mechanical properties may be attributed to the interlocking structure of the interwoven fabric, individual properties of kenaf and PET fibres, strong interfacial bonding, and resistance of the fibres to impact loading. The water absorption of the composites was studied by prolonged exposure in distilled water, and the moisture absorption pattern was found to follow Fickian behaviour.

Iron impregnated carbon materials with improved physicochemical characteristics

International Nuclear Information System (INIS)

Shah, Irfan; Adnan, Rohana; Wan Ngah, Wan Saime; Mohamed, Norita

2015-01-01

Highlights: • The morphology of raw AC was altered upon Fe impregnation and surface oxidation. • Surface modification had increased the pores diameter and surface functionalities. • Development of iron oxides have been expected on Fe impregnated carbon materials. • The M1, M2 and M3 have revealed magnetic susceptibility in applied magnetic field. • Dyes removal efficiency of M3 was notably higher (90–99%) than the raw AC (60–85%). - Abstract: This paper highlights the effect of iron impregnation and surface oxidation on the physicochemical characteristics of iron impregnated carbon materials. These materials were characterized by various techniques like surface area, pore size distribution, SEM/EDX, CHN, XRD, FTIR, TG/DT, VSM and XPS analyses. The increase in the surface functionalities and pores diameter (3.51–5.49 nm) of the iron-impregnated carbon materials was observed with the increase in iron contents and surface oxidation. The saturated magnetization values (0.029–0.034 emu/g) for the iron-impregnated carbon materials reflected the magnetic tendency due to the development of small size iron oxides on their surfaces. The XPS spectra revealed the existence of different oxidation states of the corresponding metals on the iron impregnated carbon materials. The percentage removal of model dyes (Methylene Blue and Methyl Orange) by iron-impregnated carbon materials was enhanced (>90%) with the increase in iron contents and pores diameters.

Engineering properties of a filament-wound Kevlar 49/epoxy composite

International Nuclear Information System (INIS)

Hahn, H.T.; Chin, W.K.

1981-01-01

The effect of a flywheel service environment on transverse tension and compression, and longitudinal compression and shear properties of a filament-wound Kevlar/epoxy composite are evaluated. Shear strength and modulus were reduced by moisture desorption during preconditioning in a vacuum at 75 C, although room temperature strength and modulus increased for longitudinal compression. The desorption induced cracking of the laminate plies through increased residual stresses, which at 25 C were 15 MPa, higher than the transverse strength. The 75 C temperature caused lower strength and moduli except for longitudinal tension, and the complete test results are listed

Determination of mechanical properties of carbon/epoxy plates by tensile stress test

Science.gov (United States)

Bere, Paul; Krolczyk, Jolanta B.

2017-10-01

The polymeric composite materials used in aerospace, military, medical or racing cars manufacturing end up being used in our daily life Whether we refer to the performing vehicles, subassemblies or parts for aircrafts, wind, telegraph poles, or medical prostheses they all are present in our lives and they are made of composite materials (CM). This paper presents research regarding three different composite materials, plates by carbon fiber, in epoxy matrix. Starting with materials presentation, manufacturing methodology and determination of mechanical properties at carbon fiber/epoxy were done. Vacuum bag technology to obtain the composite structure offer opportunity to get a very compact and homogeny composite structure. For the moment this technology are adequate for high performances pieces. The mechanical characteristics of plates made of composite materials reinforced presented indicates closed value like metal materials. Based on the results, a comparative study between the reinforced materials typically used to manufacture the plates of CM is carried out.

Reinforced carbon fiber laminates with oriented carbon nanotube epoxy nanocomposites: Magnetic field assisted alignment and cryogenic temperature mechanical properties.

Science.gov (United States)

He, Yuxin; Yang, Song; Liu, Hu; Shao, Qian; Chen, Qiuyu; Lu, Chang; Jiang, Yuanli; Liu, Chuntai; Guo, Zhanhu

2018-05-01

The epoxy nanocomposites with ordered multi-walled carbon nanotubes (MWCNTs) were used to influence the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) laminate at 77 K, Oxidized MWCNTs functionalized with Fe 3 O 4 (Fe 3 O 4 /O-MWCNTs) with good magnetic properties were prepared by co-precipitation method and used to modify epoxy (EP) for cryogenic applications. Fe 3 O 4 /O-MWCNTs reinforced carbon fiber epoxy composites were also prepared through vacuum-assisted resin transfer molding (VARTM). The ordered Fe 3 O 4 /O-MWCNTs were observed to have effectively improved the mechanical properties of epoxy (EP) matrix at 77 K and reduce the coefficient of thermal expansion (CTE) of EP matrix. The ordered Fe 3 O 4 /O-MWCNTs also obviously improved the micro-cracks resistance of CF/EP composites at 77 K. Compared to neat EP, the CTE of ordered Fe 3 O 4 /O-MWCNTs modified CF/EP composites was decreased 37.6%. Compared to CF/EP composites, the micro-cracks density of ordered Fe 3 O 4 /O-MWCNTs modified CF/EP composites at 77 K was decreased 37.2%. Copyright © 2018 Elsevier Inc. All rights reserved.

Methods for the characterization of impregnating pitches

Energy Technology Data Exchange (ETDEWEB)

Compin, S.; Ben Aim, R.; Couderc, P.; Saint-Romain, J.L.

1987-11-01

This paper discusses modification of the impregnation performance of various pitches. The filtration ability, which expresses the impregnation performance, was studied using gel permeation chromatography and scanning electron microscopy. 16 refs., 5 figs., 2 tabs.

Inter-Batch Variation and the Effect of Casting Vacuum on Ballistic and Mechanical Properties of a High Performing Cast Composite Rocket Propellant

Science.gov (United States)

2014-12-01

X 5 mm with a bandsaw. Longitudinal faces were coated (inhibited) with an epoxy resin and burned in a Crawford-type low pressure strand burner. The...batch (P0190) is the highest. For strain at maximum stress and strain at break the trend is reversed with the highest values for P0188 and lowest...Appendix A: Propellant Strand Burn Results Table A1: Low pressure strand burn results for P0188, full vacuum coated with epoxy R180/H180

Synthesis of polyoxometalate-loaded epoxy composites

Science.gov (United States)

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.

Predicting the tensile strength of A UD basalt/ epoxy composite used for the confinement of concrete structures

Science.gov (United States)

Ciniņa, I.; Zīle, O.; Andersons, J.

2013-01-01

The principal aim of the present research was to predict the strength of UD basalt fiber/epoxy matrix composites in tension along the reinforcement direction. Tension tests on single basalt fibers were performed to determine the functional form of their strength distribution and to evaluate the parameters of the distribution. Also, microbond tests were carried out to assess the interfacial shear strength of the fibers and polymer matrix. UD composite specimens were produced and tested for the longitudinal tensile strength. The predicted strength of the composite was found to exceed the experimental values by ca. 20%, which can be explained by imperfections in the fiber alignment, impregnation, and adhesion in the composite specimens.

Oil-Impregnated Polyethylene Films

Science.gov (United States)

Mukherjee, Ranit; Habibi, Mohammad; Rashed, Ziad; Berbert, Otacilio; Shi, Shawn; Boreyko, Jonathan

2017-11-01

Slippery liquid-infused porous surfaces (SLIPS) minimize the contact angle hysteresis of a wide range of liquids and aqueous food products. Although hydrophobic polymers are often used as the porous substrate for SLIPS, the choice of polymer has been limited to silicone-based or fluorine-based materials. Hydrocarbon-based polymers, such as polyethylene, are cost effective and widely used in food packaging applications where SLIPS would be highly desirable. However, to date there have been no reports on using polyethylene as a SLIPS substrate, as it is considered highly impermeable. Here, we show that thin films of low-density polyethylene can be stably impregnated with carbon-based oils without requiring any surface modification. Wicking tests reveal that oils with sufficient chemical compatibility follow Washburn's equation. The nanometric effective pore size of the polyethylene does result in a very low wicking speed, but by using micro-thin films and a drawdown coater, impregnation can still be completed in under one second. The oil-impregnated polyethylene films promoted ultra-slippery behavior for water, ketchup, and yogurt while remaining durable even after being submerged in ketchup for over one month. This work was supported by Bemis North America (AT-23981).

Mechanical and morphological characterizations of carbon fiber fabric reinforced epoxy composites used in aeronautical field

Directory of Open Access Journals (Sweden)

Jane Maria Faulstich de Paiva

2009-09-01

Full Text Available Carbon fiber reinforced composites (CFRC have been used in aeronautical industry in the manufacture of different aircraft components that must attend tight mechanical requirements. This paper shows a study involving mechanical (flexural, shear, tensile and compressive tests and morphological characterizations of four different laminates based on 2 epoxy resin systems (8552TM and F584TM and 2 carbon fiber fabric reinforcements (Plain Weave (PW and Eight Harness Satin (8HS. All laminates were obtained by handing lay-up of prepregs plies (0º/90º and consolidation in an autoclave following an appropriate curing cycle with vacuum and pressure. The results show that the F584-epoxy matrix laminates present better mechanical properties in the tensile and compressive tests than 8552 composites. It is also observed that PW laminates for both matrices show better flexural and interlaminar shear properties.

Replacement of hazardous chromium impregnating agent from silver/copper/chromium-impregnated active carbon using triethylenediamine to remove hydrogen sulfide, trichloromethane, ammonia, and sulfur dioxide.

Science.gov (United States)

Wu, Li-Chun; Chung, Ying-Chien

2009-03-01

Activated carbon (AC) is widely used as an effective adsorbent in many applications, including industrial-scale air purification systems and air filter systems in gas masks. In general, ACs without chemical impregnation are good adsorbents of organic vapors but poor adsorbents of low-molecular-weight or polar gases such as chlorine, sulfur dioxide (SO2), formaldehyde, and ammonia (NH3). Impregnated ACs modified with metallic impregnating agents (ASC-carbons; e.g., copper, chromium, and silver) enhance the adsorbing properties of the ACs for simultaneously removing specific poisonous gases, but disposal of the chromium metal salt used to impregnate the ACs has the potential to result in situations that are toxic to both humans and the environment, thereby necessitating the search for replaceable organic impregnating agents that represent a much lower risk. The aim of this study was to assess the gas removal efficiency of an AC in which the organic impregnating agent triethylenediamine (TEDA) largely replaced the metallic impregnating agent chromium. We assessed batch and continuous adsorption capacities in situ for removing simulated hydrogen sulfide (H2S), trichloromethane (CHCl3), NH3, and SO2 gases. Brunauer-Emmet-Teller measurements and scanning electron microscopy analyses identified the removal mechanism by which TEDA-impregnated AS-carbon (dechromium ASC-carbon) adsorbs gases and determined the removal capacity for H2S, CHCl3, NH3, and SO2 to be 311, 258, 272, and 223 mg/g-C, respectively. These results demonstrate that TEDA-impregnated AS-carbon is significantly more efficient than ASC-carbon in adsorbing these four gases. Organic TEDA-impregnating agents have also been proven to be a reliable and environmental friendly agent and therefore a safe replacement of the hazardous chromium found in conventional ASC-carbon used in removing toxic gases from the airstream.

Epoxy-based carbon nanotubes reinforced composites

CSIR Research Space (South Africa)

Kesavan Pillai, Sreejarani

2011-04-01

Full Text Available of the three major epoxy resin producers worldwide [May, 1987]. Epoxy resin is most commonly used as a matrix for advanced composites due to their superior thermal, mechanical and electrical properties; dimensional stability and chemical resistance. Epoxy... and modifiers to create products with an almost unlimited range and variety of performance properties [The epoxy book, 2000]. Epoxy resins are widely used as high-grade synthetic resins, for example, in the electronics, aeronautics and astronautic industries...

Interaction of water with epoxy.

Energy Technology Data Exchange (ETDEWEB)

Powers, Dana Auburn

2009-07-01

The chemistries of reactants, plasticizers, solvents and additives in an epoxy paint are discussed. Polyamide additives may play an important role in the absorption of molecular iodine by epoxy paints. It is recommended that the unsaturation of the polyamide additive in the epoxy cure be determined. Experimental studies of water absorption by epoxy resins are discussed. These studies show that absorption can disrupt hydrogen bonds among segments of the polymers and cause swelling of the polymer. The water absorption increases the diffusion coefficient of water within the polymer. Permanent damage to the polymer can result if water causes hydrolysis of ether linkages. Water desorption studies are recommended to ascertain how water absorption affects epoxy paint.

Impregnation of Ibuprofen into Polycaprolactone using supercritical carbon dioxide

International Nuclear Information System (INIS)

Yoganathan, Roshan; Mammucari, Raffaella; Foster, Neil R

2010-01-01

Polycaprolactone (PCL) is a Food and Drug Administration (FDA) approved biodegradable polyester used in tissue engineering applications. Ibuprofen is an anti-inflammatory drug which has good solubility in supercritical CO 2 (SCCO 2 ). The solubility of CO 2 in PCL allows for the impregnation of CO 2 -soluble therapeutic agents into the polymer via a supercritical fluid (SCF) process. Polymers impregnated with bio-active compounds are highly desired for medical implants and controlled drug delivery. In this study, the use of CO 2 to impregnate PCL with ibuprofen was investigated. The effect of operating conditions on the impregnation of ibuprofen into PCL was investigated over two pressure and two temperature levels, 150bar and 200bar, 35 0 C and 40 0 C, respectively. Polycaprolactone with drug-loadings as high as 27% w/w were obtained. Impregnated samples exhibited controlled drug release profiles over several days.

Impregnation of leather during "freeze-drying"

DEFF Research Database (Denmark)

Storch, Mikkel; Vestergaard Poulsen Sommer, Dorte; Hovmand, Ida

2016-01-01

Freeze-drying is a recognized method for the preservation of waterlogged objects. Naturally, freeze-drying has also been used for waterlogged archaeological leather often after treatment with Na2.EDTA and impregnation with PEG; but the treated leather sometimes suffers from “excessive drying......” becoming too stiff and brittle. The aim of this study was to examine the effect of a conventional freeze-drying method against an alternative freeze-drying method that preserves the natural moisture content of the leather. Both new and archaeological waterlogged leather were included in the study...... suggest that the process which takes place within the leather during the freeze-drying in not actual freeze-drying, but rather a sophisticated way of distributing the impregnating agent. The pure ice phase freezes out, but the impregnating agent remains liquid as the temperature does not become low enough...

Contact allergy to epoxy resin

DEFF Research Database (Denmark)

Bangsgaard, Nannie; Thyssen, Jacob Pontoppidan; Menné, Torkil

2012-01-01

Background. Epoxy resin monomers are strong skin sensitizers that are widely used in industrial sectors. In Denmark, the law stipulates that workers must undergo a course on safe handling of epoxy resins prior to occupational exposure, but the effectiveness of this initiative is largely unknown...... in an educational programme. Conclusion. The 1% prevalence of epoxy resin contact allergy is equivalent to reports from other countries. The high occurrence of epoxy resin exposure at work, and the limited use of protective measures, indicate that reinforcement of the law is required....

Impregnation of Ibuprofen into Polycaprolactone using supercritical carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Yoganathan, Roshan; Mammucari, Raffaella; Foster, Neil R, E-mail: n.foster@unsw.edu.a [Supercritical Fluids Research Group, School of Chemical Sciences and Engineering, University of New South Wales, NSW 2052 (Australia)

2010-03-01

Polycaprolactone (PCL) is a Food and Drug Administration (FDA) approved biodegradable polyester used in tissue engineering applications. Ibuprofen is an anti-inflammatory drug which has good solubility in supercritical CO{sub 2} (SCCO{sub 2}). The solubility of CO{sub 2} in PCL allows for the impregnation of CO{sub 2}-soluble therapeutic agents into the polymer via a supercritical fluid (SCF) process. Polymers impregnated with bio-active compounds are highly desired for medical implants and controlled drug delivery. In this study, the use of CO{sub 2} to impregnate PCL with ibuprofen was investigated. The effect of operating conditions on the impregnation of ibuprofen into PCL was investigated over two pressure and two temperature levels, 150bar and 200bar, 35{sup 0}C and 40 {sup 0}C, respectively. Polycaprolactone with drug-loadings as high as 27% w/w were obtained. Impregnated samples exhibited controlled drug release profiles over several days.

Caracterização de um pré-impregnado aeronáutico por FT-IR e análise térmica Characterization of pre-impregnated of epoxy resin/carbon fiber

Directory of Open Access Journals (Sweden)

Vanesa C. G. M. Ferrari

2012-01-01

Full Text Available Este trabalho consiste na caracterização de um pré-impregnado ("prepreg" de resina epoxídica/fibra de carbono, usando-se espectroscopia no infravermelho com transformada de Fourier (FT-IR, análise termogravimétrica (TG, calorimetria exploratória diferencial (DSC e análise térmica dinâmico-mecânica (DMTA. A análise por FT-IR foi realizada nos modos de transmissão (pastilha de KBr, pirólise em bico de Bunsen e controlada e detecção fotoacústica (PAS. Os espectros de FT-IR de transmissão revelaram a presença de resina epoxídica, grupos ciano, amínicos e bisfenol A, que possibilitaram identificar o provável agente de cura:a cianoguanidina (ou dicianodiamida do sistema epoxídico. Os espectros de FT-IR/PAS permitiram acompanhar as alterações espectrométricas causadas pela cura. A análise térmica auxiliou na observação e compreensão dos eventos durante o processo de cura, etapas de gelificação e vitrificação, e da influência destas nas temperaturas de transição vítrea (Tg do material curado e na escolha do intervalo de temperatura de cura, que é um dos parâmetros mais importantes do processo produtivo.This work explores the characterization of pre-impregnated ("prepreg" materials made with an epoxy resin/carbon fiber, using FT-IR spectroscopy, thermogravimetry (TG, differential scanning calorimetry (DSC and dynamic mechanical thermal analysis (DMTA. FT-IR spectroscopy was used in the transmission mode (KBr pellets, pyrolysis without control and controlled pyrolysis and photoacoustic detection (FT-IR/PAS. The transmission FT-IR spectra revealed the presence of epoxy resin, cyano groups, amine and bisphenol A, which allowed us to identify the probable agent of cure: cyanoguanidine (or DCD. With FT-IR/PAS it was possible to monitor spectrometric changes caused by curing. The thermal analysis assisted in observing and understanding events during the curing process, including the gelation and vitrification steps. It

Effect of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites

Science.gov (United States)

Ridzuan, M. J. M.; Majid, M. S. Abdul; Afendi, M.; Firdaus, A. Z. Ahmad; Azduwin, K.

2017-11-01

The effects of elevated temperature on the tensile strength of Napier/glass-epoxy hybrid reinforced composites and its morphology of fractured surfaces are discussed. Napier/glass-epoxy hybrid reinforced composites were fabricated by using vacuum infusion method by arranging Napier fibres in between sheets of woven glass fibres. Napier and glass fibres were laminated with estimated volume ratios were 24 and 6 vol. %, respectively. The epoxy resin was used as matrix estimated to 70 vol. %. Specimens were tested to failure under tension at a cross-head speed of 1 mm/min using Universal Testing Machine (Instron) with a load cell 100 kN at four different temperatures of RT, 40°C, 60°C and 80°C. The morphology of fractured surface of hybrid composites was investigated by field emission scanning electron microscopy. The result shows reduction in tensile strength at elevated temperatures. The increase in the temperature activates the process of diffusion, and generates critical stresses which cause the damage at first-ply or at the centre of the hybrid plate, as a result lower the tensile strength. The observation of FESEM images indicates that the fracture mode is of evolution of localized damage, from fibre/matrix debonding, matric cracking, delamination and fibre breakage.

Highlights from the assembly of the helical field coils for the Advanced Toroidal Facility

International Nuclear Information System (INIS)

Benson, R.D.

1985-01-01

The helical field (HF) coils in the Advanced Toroidal Facility (ATF) device consist of a set of 24 identical segments connected to form a continuous pair of helical coils wrapped around a toroidal vacuum vessel. Each segment weighs approximately 1364 kg (3000 lb) and is composed of 14 water-cooled copper plate conductors bolted to a cast stainless steel structural support member with a T-shape cross section (known as the structural tee). The segment components are electrically insulated with Kapton adhesive tape, G-10, Tefzel, and rubber to withstand 2.5 kV. As a final insulator and structural support, the entire segment is vacuum impregnated with epoxy. This paper offers a brief overview of the processes used to assemble the component parts into a completed segment, including identification of items that required special attention. 4 figs

Evaluation of methods for increasing vacuum breakdown strength

International Nuclear Information System (INIS)

Evans, R.D.; Cooke, C.M.; Berman, E.R.

1977-01-01

Research to determine the effectiveness of coated and gas shielded cathodes as a means of increasing vacuum breakdown strength under short pulse conditions is reported. A technique for rapidly evaluating large numbers of coatings on small electrodes at relatively low pulse voltage (120 kV or less) and methods for testing larger electrodes and fewer coatings at higher total voltage were developed. Experiments with gas shielded cathodes were also conducted. Results suggest that it may be possible to eliminate prebreakdown current and to double breakdown strength by applying a suitable coating to the cathode. Breakdown stresses in excess of 2 MV/cm were obtained in a 0.5 mm gap with sputtered coatings of alumina, Cr 2 O 3 , and several readily available epoxies. Electrodes two orders of magnitude greater in area were tested, and stresses approaching 1 MV/cm were measured in 5 mm gaps for several epoxies and for alumina. It has further been shown that, because similar trends occurred in the data from large and small experiments, it should be possible to screen potential coatings rapidly and effectively with minimum expenditure using a method similar to that employed for small electrodes at low pulse voltage

Wettability of nano-epoxies to UHMWPE fibers.

Science.gov (United States)

Neema, S; Salehi-Khojin, A; Zhamu, A; Zhong, W H; Jana, S; Gan, Y X

2006-07-01

Ultra high molecular weight polyethylene (UHMWPE) fibers have a unique combination of outstanding mechanical, physical, and chemical properties. However, as reinforcements for manufacturing high performance composite materials, UHMWPE fibers have poor wettability with most polymers. As a result, the interfacial bonding strength between the fibers and polymer matrices is very low. Recently, developing so-called nano-matrices containing reactive graphitic nanofibers (r-GNFs) has been proposed to promote the wetting of such matrices to certain types of fiber reinforcements. In this work, the wettability of UHMWPE fibers with different epoxy matrices including a nano-epoxy, and a pure epoxy was investigated. Systematic experimental work was conducted to determine the viscosity of the epoxies, the contact angle between the epoxies and the fibers. Also obtained are the surface energy of the fibers and the epoxies. The experimental results show that the wettability of the UHMWPE fibers with the nano-epoxy is much better than that of the UHMWPE fibers with the pure epoxy.

Mechanical behavior of glass/epoxy composite laminate with varying amount of MWCNTs under different loadings

Science.gov (United States)

Singh, K. K.; Rawat, Prashant

2018-05-01

This paper investigates the mechanical response of three phased (glass/MWCNTs/epoxy) composite laminate under three different loadings. Flexural strength, short beam strength and low-velocity impact (LVI) testing are performed to find an optimum doping percentage value for maximum enhancement in mechanical properties. In this work, MWCNTs were used as secondary reinforcement for three-phased composite plate. MWCNT doping was done in a range of 0–4 wt% of the thermosetting matrix system. Symmetrical design eight layered glass/epoxy laminate with zero bending extension coupling laminate was fabricated using a hybrid method i.e. hand lay-up technique followed by vacuum bagging method. Ranging analysis of MWCNT mixing highlighted the enhancement in flexural, short beam strength and improvement in damage tolerance under LVI loading. While at higher doping wt%, agglomeration of MWCNTs are observed. Results of mechanical testing proposed an optimized doping value for maximum strength and damage resistance of the laminate.

Influence of double-diaphragm vacuum compaction on deformation during forming of composite prepregs

Directory of Open Access Journals (Sweden)

Hassan Alshahrani

2016-12-01

Full Text Available During the diaphragm forming process, a vacuum seal is applied between the upper and lower diaphragms to compact and hold the laminate. Therefore, a thorough characterization of the in-plane shear behavior of fabrics under diaphragm forming conditions must take into account the effect of vacuum-sealing and compaction between the two diaphragms during bias extension. The study presented here examined the shear angles of out-of-autoclave 8-harness satin woven carbon/epoxy prepregs under diaphragm compaction. A bias extension test was conducted to study the effect of diaphragm compaction and ply interactions on shear properties. The test was performed at different compaction levels, and changes in shear angle with respect to vacuum levels and diaphragm compaction forces were observed. The contribution of diaphragm material and ply interaction to shear stiffness was evaluated and compared with results from a direct bias extension test. The samples were tested at both room temperature and at elevated temperatures using a radiant heater. The results show that shear angle decreases significantly as vacuum pressure and compaction is applied between the two diaphragms. This finding indicates that vacuum levels and compaction forces have a significant influence on the deformation limit and wrinkling onset during the diaphragm forming process.

Epoxy-based carbon nanotubes reinforced composites

CSIR Research Space (South Africa)

Kesavan Pillai, Sreejarani

2011-04-01

Full Text Available of the three major epoxy resin producers worldwide [May, 1987]. Epoxy resin is most commonly used as a matrix for advanced composites due to their superior thermal, mechanical and electrical properties; dimensional stability and chemical resistance. Epoxy... are electrical insulators, and the widespread use of the epoxy resins for many high-performance applications is constrained because of their inherent brittleness, delamination and fracture toughness limitations. There were quite a few approaches to enhance...

Experimental Investigation on Mechanical and Thermal Properties of Marble Dust Particulate-Filled Needle-Punched Nonwoven Jute Fiber/Epoxy Composite

Science.gov (United States)

Sharma, Ankush; Patnaik, Amar

2018-03-01

The present investigation evaluates the effects of waste marble dust, collected from the marble industries of Rajasthan, India, on the mechanical properties of needle-punched nonwoven jute fiber/epoxy composites. The composites with varying filler contents from 0 wt.% to 30 wt.% marble dust were prepared using vacuum-assisted resin-transfer molding. The influences of the filler material on the void content, tensile strength, flexural strength, interlaminar shear strength (ILSS), and thermal conductivity of the hybrid composites have been analyzed experimentally under the desired optimal conditions. The addition of marble dust up to 30 wt.% increases the flexural strength, ILSS, and thermal conductivity, but decreases the tensile strength. Subsequently, the fractured surfaces of the particulate-filled jute/epoxy composites were analyzed microstructurally by field-emission scanning electron microscopy.

Effect of mesh-peel ply variation on mechanical properties of E-glas composite by infusion vacuum method

Science.gov (United States)

Abdurohman, K.; Siahaan, Mabe

2018-04-01

Composite materials made of glass fiber EW-135 with epoxy lycal resin with vacuum infusion method have been performed. The dried glass fiber is arranged in a mold then connected to a vacuum machine and a resin tube. Then, the vacuum machine is turned on and at the same time the resin is sucked and flowed into the mold. This paper reports on the effect of using mesh- peel ply singles on upper-side laminates called A and the effect of using double mesh-peel ply on upper and lower-side laminates call B with glass fiber arrangement is normal and ± 450 in vacuum infusion process. Followed by the manufacture of tensile test specimen and tested its tensile strength with universal test machine 100kN Tensilon RTF 2410, at room temperature with constant crosshead speed. From tensile test results using single and double layers showed that double mesh-peel ply can increase tensile strength 14% and Young modulus 17%.

Thermally activated, single component epoxy systems

KAUST Repository

Unruh, David A.; Pastine, Stefan J.; Moreton, Jessica C.; Frechet, Jean

2011-01-01

A single component epoxy system in which the resin and hardener components found in many two-component epoxies are combined onto the same molecule is described. The single molecule precursor to the epoxy resin contains both multiple epoxide moieties and a diamine held latent by thermally degradable carbamate linkages. These bis-carbamate "single molecule epoxies" have an essentially infinite shelf life and access a significant range in curing temperatures related to the structure of the carbamate linkages used. © 2011 American Chemical Society.

Thermally activated, single component epoxy systems

KAUST Repository

Unruh, David A.

2011-08-23

A single component epoxy system in which the resin and hardener components found in many two-component epoxies are combined onto the same molecule is described. The single molecule precursor to the epoxy resin contains both multiple epoxide moieties and a diamine held latent by thermally degradable carbamate linkages. These bis-carbamate "single molecule epoxies" have an essentially infinite shelf life and access a significant range in curing temperatures related to the structure of the carbamate linkages used. © 2011 American Chemical Society.

Wood construction and magnetic characteristics of impregnated type magnetic wood

International Nuclear Information System (INIS)

Oka, Hideo; Hojo, Atsushi; Seki, Kyoushiro; Takashiba, Toshio

2002-01-01

The results of experiments involving the AC and DC magnetic characteristics of impregnated type magnetic wood were studied by taking into consideration the wood construction and fiber direction. The experimental results show that the sufficient amount of impregnated magnetic fluid varies depending on the fiber direction and length, and the grain face of the wood material. The impregnated type magnetic wood sample that is fully impregnated by magnetic fluid has a 60% saturation magnetization compared to the saturation magnetization of magnetic fluid. Samples for which the wood fiber direction was the same as the direction of the magnetic path had a higher magnetization intensity and permeability

A composite vacuum barrier for the LHC short straight section

International Nuclear Information System (INIS)

Jenny, B.; Rohmig, P.; Uriarte, J.M.

1996-01-01

The lattice of the CERN Large Hadron Collider (LHC) will contain 384 Short Straight Section (SSS) units, one in every 53 m half-cell. The SSS is composed of a twin aperture high-field superconducting quadrupole and of two combined-function corrector magnets operating in pressurized helium at 1.9 K. The SSS cryostat contains also a barrier for sectorisation of the insulation vacuum. The vacuum barrier is mounted between the helium vessel and the vacuum enclosure. Its functions are to limit the extent of eventual helium leaks and to facilitate the leak detection and the pumping-down from atmospheric pressure. During installation of the LHC, the vacuum barrier permits independent testing of the half-cells, thus enabling higher installation rates. In parallel to a conventional barrier made out of austenitic stainless steel, a barrier of composite material was developed, taking advantage of the lower thermal conductivity of glass fibre reinforced epoxy resin, and with the aim of reducing costs for LHC. The thermo-mechanical design together with the conception and the moulding techniques used for the manufacture of the prototype are described. Bonding techniques for the leak tight stainless steel composite interfaces are presented and test results shown. Results on the mechanical performance and on the helium tests carried out on the prototype are given

E12 sheet plastination: Techniques and applications.

Science.gov (United States)

Ottone, Nicolas Ernesto; Baptista, Carlos A C; Latorre, Rafael; Bianchi, Homero Felipe; Del Sol, Mariano; Fuentes, Ramon

2017-10-30

Plastination is an anatomical technique that consists of replacing the liquids and fat of specimens by reactive polymers through forced impregnation in a vacuum. These are then polymerized to achieve the final result. E12 sheet plastination involves epoxy resin impregnation of thin (2-4 mm) and ultra-thin (SciELO databases, and manual searches. After searching, 616 records were found using the online and manual searches (MEDLINE, n: 207; EMBASE, n: 346; SciELO, n: 44; Manual search: 23). Finally, 96 records were included in this review (after duplicates and articles unrelated to the subject were excluded). The aim of this work was to review the E12 sheet plastination technique, searching for articles concerning views of it, identifying the different variants implemented by researchers since its creation by Gunther von Hagens, and to identify its applications from teaching and research in anatomy to morphological sciences. Clin. Anat., 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Nb3Sn dipole magnet reacted after winding

International Nuclear Information System (INIS)

Taylor, C.; Scanlan, R.; Peters, C.; Wolgast, R.; Gilbert, W.; Hassenzahl, W.; Meuser, R.; Rechen, J.

1984-09-01

A 5 cm bore dia., 1-m-long dipole model magnet was constructed by winding un-reacted cable, followed by reaction and epoxy-impregnation. Experience and test results are described on the 1.7 mm dia. internal-tin wire, the eleven-strand flattened cable, fiberglass insulation, and construction of the magnet. Each half of the magnet has two double-pancake-type windings that were reacted in a single operation. The two double-pancakes were then separately vacuum impregnated after soldering the flexible Nb-Ti leads to the Nb 3 Sn conductors. No iron flux return yoke was used. In initial tests a central field of 8.0 T was reached at 4.4 K. However, evidence from training behavior, and 1.8 K tests indicate that premature quenching, rather than critical current of the cable, limited the field intensity. The magnet was reassembled and more rigidly clamped; additional test results are reported

PROTECTIVE TREATMENT OF WOOD IMPREGNATING COMPOSITION OF PETROCHEMICAL WASTE

Directory of Open Access Journals (Sweden)

T. V. Maslakova

2015-01-01

Full Text Available The paper presents results of experimental and theoretical studies aimed at expanding the applications of the copolymers on the basis of the waste styrene production. One of the areas is used as impregnating compositions of wood materials, selection of optimal conditions modification on samples of the most widely used in the industry of wood, such as birch, aspen and other. Studies were conducted to obtain and use an impregnating compositions based on copolymers synthesized from waste products of styrene and the cubic remainder rectification of ethylbenzene (CRRE for the protective treatment of birch wood. Identified physic-chemical characteristics of physical mixtures of copolymers «CORS», «STAM», CRRE at different ratios. Studied the process of modification birch using the method of experiment planning greco-latin square of the fourth order, and the influence of such factors as the temperature of the impregnating composition, the duration of the impregnation, the temperature and duration of thermal treatment on the performance moisture resistance of wood. Were established optimal conditions modification birch wood treated impregnating compositions on the basis of physical mixtures of copolymer «CORS» with CRRE and copolymer «STAM» with CRRE is the mixing ratio 2:1, the duration and temperature of the impregnation 7 h and 95 0C, time and temperature of heat treatment 7 h and 170 0C, respectively. A sealing composition containing CRRE with copolymer «STAM» 1:2 is more preferable, as in the structure of the copolymer «STAM» contains carboxyl and anhydrite group. Thus was justified use for the modification of natural wood impregnating compositions on the basis of physical mixtures of CRRE with copolymers «CORS» and «STAM», which improve the properties of wood, increase moisture and weather resistance more than twice.

Characterization of Epoxy Functionalized Graphite Nanoparticles and the Physical Properties of Epoxy Matrix Nanocomposites

Science.gov (United States)

Miller, Sandi G.; Bauer, Jonathan L.; Maryanski, Michael J.; Heimann, Paula J.; Barlow, Jeremy P.; Gosau, Jan-Michael; Allred, Ronald E.

2010-01-01

This work presents a novel approach to the functionalization of graphite nanoparticles. The technique provides a mechanism for covalent bonding between the filler and matrix, with minimal disruption to the sp2 hybridization of the pristine graphene sheet. Functionalization proceeded by covalently bonding an epoxy monomer to the surface of expanded graphite, via a coupling agent, such that the epoxy concentration was measured as approximately 4 wt.%. The impact of dispersing this material into an epoxy resin was evaluated with respect to the mechanical properties and electrical conductivity of the graphite-epoxy nanocomposite. At a loading as low as 0.5 wt.%, the electrical conductivity was increased by five orders of magnitude relative to the base resin. The material yield strength was increased by 30% and Young s modulus by 50%. These results were realized without compromise to the resin toughness.

Radiation hardenable impregnating agents for the consolidating conservation of wooden objects

International Nuclear Information System (INIS)

Schaudy, R.

1985-01-01

Radiation hardenable impregnating agents offer some advantages over the conventional agents. At the author's institution objects up to 110 cm length can be impregnated for conservation. More than 200 monomers and resins have been investigated. The procedure of impregnation is outlined and some kinds of wooden objects conserved in this way listed. (G.W.)

21 CFR 529.1003 - Flurogestone acetate-impregnated vaginal sponge.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Flurogestone acetate-impregnated vaginal sponge... § 529.1003 Flurogestone acetate-impregnated vaginal sponge. (a) Specifications. Each vaginal sponge... ewes during their normal breeding season. (2) Limitations. Using applicator provided, insert sponge...

Preparation of Sr adsorptive fiber by impregnating with crown ether derivative for 90Sr measurement

International Nuclear Information System (INIS)

Horita, Takuma; Asai, Shiho; Hanzawa, Yukiko; Kitatsuji, Yoshihiro; Konda, Miki; Saito, Kyoichi; Fujiwara, Kunio; Sugo, Takanobu

2017-01-01

A Sr adsorption fiber was prepared for rapid analysis of 90 Sr content in the fiber using radiation-induced emulsion graft polymerization and subsequent chemical modification. A polyethylene fiber with a diameter of 13 μm was first immersed in a methanol solution of an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), and polyoxyethylene sorbitol ester (Tween20) as a surfactant for the graft-polymerization of GMA. Octadecylamine was then bound to a polymer chain extending from the fiber surface, providing hydrophobicity to the polymer chain. Dicyclohexano-18-crown-6 (DCH18C6) was finally impregnated onto the polymer chain via a hydrophobic interaction between the octadecyl moiety of the polymer chain and the cyclohexyl moiety of DCH18C6. The fiber surface structure, characterized by DCH18C6 molecules loosely entangled with polymer chains, allowed for the rapid adsorption of Sr ions at an adsorption rate of approximately 100-times higher than that of a commercially available Sr-selective resin (Sr Resin ® ). (author)

Physicochemical properties of vanadium impregnated Al-PILCs: Effect of vanadium source

Energy Technology Data Exchange (ETDEWEB)

Balci, Suna, E-mail: sunabalci@gazi.edu.tr; Tecimer, Aylin

2015-03-01

Graphical abstract: - Highlights: • Vanadium was incorporated into Al-PILC using NaVO{sub 3} or VOSO{sub 4}·3H{sub 2}O precursors by wet impregnation, washing after wet impregnation and impregnation from solution methods. • The layered structure of the supports was retained after the vanadium incorporation. • Incorporation took place both by settling and ion exchange mechanism with the treatment VOSO{sub 4}·3H{sub 2}O precursor while settling was dominant in the use of NaVO{sub 3} precursor. • Treatment with VOSO{sub 4}·3H{sub 2}O which was acidic in solution resulted in more structural deformation. • V{sub 2}O{sub 5} and VO{sub 2} were found as the major oxide forms on the impregnated samples. Loading of vanadyl sulfate hydrate (VOSO{sub 4}·H{sub 2}O) resulted in higher V/Si ratio. Most of the vanadium was bonded in +5 oxide form. • Changes in the FTIR signals after vanadium incorporation caused by Brønsted and Lewis sites, silanol, water and vanadium vibrations were occured. • Dehydroxylation of the structure took place around 300 °C. Samples obtained by impregnation and washing after wet impregnation methods resulted in similar mass losses and the wet impregnated sample showed the highest mass loss among the impregnated samples. - Summary: Clay from the Middle Anatolian previously pillared by Al{sub 13}-Keggin ions and then calcined at 300 °C (Al-PILC) was impregnated with aqueous solutions of vanadium precursors by impregnation from solution (I), wet impregnation (WI) and washing after wet impregnation (WWI) methods. The crystal and textural properties were evaluated by X-ray powder diffraction (XRD), nitrogen sorption and transmission electron microscopy (TEM) images. Vanadium incorporation into the Al-PILC resulted decreases in the basal spacing from 1.75 nm to 1.35 nm with the preserved typical layered structure. The use of sodium metavanadate (NaVO{sub 3}) as the source and the impregnation from solution as the incorporation method

Innovative Chemical Process for Recycling Thermosets Cured with Recyclamines® by Converting Bio-Epoxy Composites in Reusable Thermoplastic—An LCA Study

Directory of Open Access Journals (Sweden)

Angela D. La Rosa

2018-02-01

Full Text Available An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the environmental impact by means of the Life Cycle Assessment (LCA method. Because of the need to recycle and recover materials at their end of life, the Connora process creates a great innovation in the market of epoxy composites, as they are notoriously not recyclable. Connora Technologies developed a relatively gentle chemical recycling process that induces the conversion of thermosets into thermoplastics. The LCA demonstrated that low environmental burdens are associated with the process itself and, furthermore, impacts are avoided due to the recovery of the epoxy-composite constituents (fibres and matrix. A carbon fibre (CF epoxy-composite panel was produced through Vacuum Resin Transfer Moulding (VRTM and afterwards treated using the Connora recycling process. The LCA results of both the production and the recycling phases are reported.

Thermal conductivity and Kapitza resistance of epoxy resin fiberglass tape at superfluid helium temperature

Science.gov (United States)

Baudouy, B.; Polinski, J.

2009-03-01

The system of materials composed of fiberglass epoxy resin impregnated tape constitutes in many cases the electrical insulation for "dry"-type superconducting accelerator magnet such as Nb 3Sn magnets. Nb 3Sn magnet technology is still under development in a few programs to reach higher magnetic fields than what NbTi magnets can produce. The European program, Next European Dipole (NED), is one of such programs and it aims to develop and construct a 15 T class Nb 3Sn magnet mainly for upgrading the Large Hardron Collider. Superfluid helium is considered as one possible coolant and since the magnet has been designed with a "dry" insulation, the thermal conductivity and the Kapitza resistance of the electrical insulation are the key properties that must be know for the thermal design of such a magnet. Accordingly, property measurements of the epoxy resin fiberglass tape insulation system developed for the NED project was carried out in superfluid helium. Four sheets with thicknesses varying from 40 to 300 μm have been tested in a steady-state condition. The determined thermal conductivity, k, is [(25.8 ± 2.8) · T - (12.2 ± 4.9)] × 10 -3 W m -1 K -1 and the Kapitza resistance is given by R K = (1462 ± 345) · T(-1.86 ± 0.41) × 10 -6 Km 2 W -1 in the temperature range of 1.55-2.05 K.

Impregnation transition in a powder

Science.gov (United States)

Raux, Pascal; Cockenpot, Heloise; Quere, David; Clanet, Christophe

2011-11-01

When an initially dry pile of micrometrical grains comes into contact with a liquid, one can observe different behaviors, function of the wetting properties. If the contact angle with the solid is low, the liquid will invade the pile (impregnation), while for higher contact angles, the grains will stay dry. We present an experimental study of this phenomenon: a dry pile of glass beads is deposed on the liquid surface, and we vary the contact angle of the liquid on the grains. We report a critical contact angle below which impregnation always occurs, and develop a model to explain its value. Different parameters modifying this critical contact angle are also investigated. Collaboration with Marco Ramaioli, Nestle Research Center, Lausanne, Switzerland.

Durability of Gamma Irradiated Polymer Impregnated Blended Cement Pastes

International Nuclear Information System (INIS)

Khattab, M.M.; Abdel-Rahman, H.A.; Younes, M.M.

2010-01-01

This study is focusing on durability and performance of the neat blended cement paste as well as those of the polymer-impregnated paste towards seawater and various concentrations of magnesium sulfate solutions up to 6 months of curing. The neat blended cement paste is prepared by a partial substitution of ordinary Portland cement with 5% of active rice husk ash (RHA). These samples were cured under tap water for 7 days. Similar samples were impregnated with unsaturated polyester resin (UPE) and subjected to various doses of gamma rays ranging from 10 to 50 kGy. The results showed that the irradiated impregnated specimens gave higher values of compressive strength than the neat blended cement paste specimens. On immersing the neat blended cement specimens and polymer impregnated specimens especially that irradiated at 30 kGy in seawater and different concentrations of magnesium sulfate solutions up to 6 months of curing, the results showed that the polymer impregnated blended cement (OPC-RHA-UPE) paste have a good resistance towards aggressive media as compared to the neat blended cement (OPC-RHA) paste. The results also indicated that the sea water has a greater corrosive effect than the magnesium sulfate solutions. These results were confirmed by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP)

Removal of hydrogen sulfide and sulfur dioxide by carbons impregnated with triethylenediamine.

Science.gov (United States)

Wu, Li-Chun; Chang, Tsu-Hua; Chung, Ying-Chien

2007-12-01

Activated carbon (AC) adsorption has long been considered to be a readily available technology for providing protection against exposure to acutely toxic gases. However, ACs without chemical impregnation have proven to be much less efficient than impregnated ACs in terms of gas removal. The impregnated ACs in current use are usually modified with metalloid impregnation agents (ASC-carbons; copper, chromium, or silver) to simultaneously enhance the chemical and physical properties of the ACs in removing specific poisonous gases. These metalloid agents, however, can cause acute poisoning to both humans and the environment, thereby necessitating the search for organic impregnation agents that present a much lower risk. The aim of the study reported here was to assess AC or ASC-carbon impregnated with triethylenediamine (TEDA) in terms of its adsorption capability for simulated hydrogen sulfide (H2S) and sulfur dioxide (SO2) gases. The investigation was undergone in a properly designed laboratory-scale and industrial fume hood evaluation. Using the system reported here, we obtained a significant adsorption: the removal capability for H2S and SO2 was 375 and 229 mg/g-C, respectively. BET measurements, element analysis, scanning electron microscopy, and energy dispersive spectrometry identified the removal mechanism for TEDA-impregnated AC to be both chemical and physical adsorption. Chemical adsorption and oxidation were the primary means by which TEDA-impregnated ASC-carbons removed the simulated gases.

Surface treated fly ash filled modified epoxy composites

Directory of Open Access Journals (Sweden)

Uma Dharmalingam

2015-01-01

Full Text Available Abstract Fly ash, an inorganic alumino silicate has been used as filler in epoxy matrix, but it reduces the mechanical properties due to its poor dispersion and interfacial bonding with the epoxy matrix. To improve its interfacial bonding with epoxy matrix, surface treatment of fly ash was done using surfactant sodium lauryl sulfate and silane coupling agent glycidoxy propyl trimethoxy silane. An attempt is also made to reduce the particle size of fly ash using high pressure pulverizer. To improve fly ash dispersion in epoxy matrix, the epoxy was modified by mixing with amine containing liquid silicone rubber (ACS. The effect of surface treated fly ash with varying filler loadings from 10 to 40% weight on the mechanical, morphological and thermal properties of modified epoxy composites was investigated. The surface treated fly ash was characterized by particle size analyzer and FTIR spectra. Morphological studies of surface treated fly ash filled modified epoxy composites indicate good dispersion of fillers in the modified epoxy matrix and improves its mechanical properties. Impact strength of the surface treated fly ash filled modified epoxy composites show more improvement than unmodified composites.

Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Directory of Open Access Journals (Sweden)

Ayrton Alef Castanheira Pereira

2016-02-01

Full Text Available Abstract The water absorption behavior of the DGEBA/TETA epoxy system was evaluated as a function of the epoxy monomer to amine hardener ratio. Weight gain versus immersion time curves were obtained and the experimental points were fitted using Fickian and Non-Fickian diffusion models. The results obtained showed that for all epoxy monomer to hardener ratios analyzed water diffusion followed non-Fickian behavior. It was possible to correlate the water absorption behavior to the macromolecular structure developed when the epoxy/ hardener ratio was varied. All epoxy/hardener ratios present a two-phase macromolecular structure, composed of regions with high crosslink density and regions with lower crosslinking. Epoxy rich systems have a more open macromolecular structure with a lower fraction of the dense phase than the amine rich systems, which present a more compact two-phase structure.

Characteristics of scandate-impregnated cathodes with sub-micron scandia-doped matrices

International Nuclear Information System (INIS)

Yuan Haiqing; Gu Xin; Pan Kexin; Wang Yiman; Liu Wei; Zhang Ke; Wang Jinshu; Zhou Meiling; Li Ji

2005-01-01

We describe in this paper scandate-impregnated cathodes with sub-micron scandia-doped tungsten matrices having an improved uniformity of the Sc distribution. The scandia-doped tungsten powders were made by both liquid-solid doping and liquid-liquid doping methods on the basis of previous research. By improving pressing, sintering and impregnating procedures, we have obtained scandate-impregnated cathodes with a good uniformity of the Sc 2 O 3 - distribution. The porosity of the sub-micron structure matrix and content of impregnants inside the matrix are similar to those of conventionally impregnated cathodes. Space charge limited current densities of more than 30 A/cm 2 at 850 deg. C b have been obtained in a reproducible way. The current density continuously increases during the first 2000 h life test at 950 deg. C b with a dc load of 2 A/cm 2 and are stable for at least 3000 h

The application of epoxy resin coating in grounding grid

Science.gov (United States)

Hu, Q.; Chen, Z. R.; Xi, L. J.; Wang, X. Y.; Wang, H. F.

2018-01-01

Epoxy resin anticorrosion coating is widely used in grounding grid corrosion protection because of its wide range of materials, good antiseptic effect and convenient processing. Based on the latest research progress, four kinds of epoxy anticorrosive coatings are introduced, which are structural modified epoxy coating, inorganic modified epoxy coating, organic modified epoxy coating and polyaniline / epoxy resin composite coating. In this paper, the current research progress of epoxy base coating is analyzed, and prospected the possible development direction of the anti-corrosion coating in the grounding grid, which provides a reference for coating corrosion prevention of grounding materials.

Vegetable oil-derived epoxy monomers and polymer blends: A comparative study with review

Directory of Open Access Journals (Sweden)

T. P. Schuman

2013-03-01

Full Text Available Glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS and linseed oil (EGL have been synthesized to have higher oxirane content, more reactivity and lower viscosity than epoxidized soybean oil (ESO or epoxidized linseed oil (ELO. The EGS and ESO, for comparison, were used neat and in blends with diglycidyl ether of bisphenol A (DGEBA. Thermosetting resins were fabricated with the epoxy monomers and either BF3 catalyst or anhydride. The curing behaviors, glass transition temperatures, crosslink densities and mechanical properties were tested. The results indicated that polymer glass transition temperatures were mostly a function of oxirane content with additional influence of glycidyl versus internal oxirane reactivity, pendant chain content, and chemical structure and presence of saturated components. EGS provided better compatibility with DGEBA, improved intermolecular crosslinking and glass transition temperature, and yielded mechanically stronger polymerized materials than materials obtained using ESO. Other benefits of the EGS resin blend systems were significantly reduced viscosities compared to either DGEBA or ESO-blended DGEBA counterparts. Therefore, EGS that is derived from renewable sources has improved potential for fabrication of structural and structurally complex epoxy composites, e.g., by vacuum-assisted resin transfer molding.

Contact allergy to epoxy (meth)acrylates.

Science.gov (United States)

Aalto-Korte, Kristiina; Jungewelter, Soile; Henriks-Eckerman, Maj-Len; Kuuliala, Outi; Jolanki, Riitta

2009-07-01

Contact allergy to epoxy (meth)acrylates, 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (bis-GMA), 2,2-bis[4-(2-hydroxy-3-acryloxypropoxy)phenyl]-propane (bis-GA), 2,2-bis[4-(methacryl-oxyethoxy)phenyl] propane (bis-EMA), 2,2-bis[4-(methacryloxy)phenyl]-propane (bis-MA), and glycidyl methacrylate (GMA) is often manifested together with contact allergy to diglycidyl ether of bisphenol A (DGEBA) epoxy resin. To analyse patterns of concomitant allergic reactions to the five epoxy (meth)acrylates in relation to exposure. We reviewed the 1994-2008 patch test files at the Finnish Institute of Occupational Health (FIOH) for reactions to the five epoxy (meth)acrylates, and examined the patients' medical records for exposure. Twenty-four patients had an allergic reaction to at least one of the studied epoxy (meth)acrylates, but specific exposure was found only in five patients: two bis-GMA allergies from dental products, two bis-GA allergies from UV-curable printing inks, and one bis-GA allergy from an anaerobic glue. Only 25% of the patients were negative to DGEBA epoxy resin. The great majority of allergic patch test reactions to bis-GMA, bis-GA, GMA and bis-EMA were not associated with specific exposure, and cross-allergy to DGEBA epoxy resin remained a probable explanation. However, independent reactions to bis-GA indicated specific exposure. Anaerobic sealants may induce sensitization not only to aliphatic (meth)acrylates but also to aromatic bis-GA.

Design of carbon nanofiber embedded conducting epoxy resin

International Nuclear Information System (INIS)

Gantayat, Subhra; Sarkar, Niladri; Rout, Dibyaranjan; Swain, Sarat K.

2017-01-01

Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices. - Highlights: • Epoxy/t-CNF nanocomposites are characterized by XRD, FTIR, SEM, AFM and TEM. • Electrical conductivity was achieved by epoxy with a threshold at 1 wt% of t-CNF. • Tensile strength is enhanced by 40% due to dispersion of t-CNF. • Synthesized nanocomposites are suitable for fabricating electronic devises.

Design of carbon nanofiber embedded conducting epoxy resin

Energy Technology Data Exchange (ETDEWEB)

Gantayat, Subhra [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India); School of Applied Sciences, KIIT University, Bhubaneswar 751024, Odisha (India); Sarkar, Niladri [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India); Rout, Dibyaranjan [School of Applied Sciences, KIIT University, Bhubaneswar 751024, Odisha (India); Swain, Sarat K., E-mail: swainsk2@yahoo.co.in [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha (India)

2017-01-15

Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices. - Highlights: • Epoxy/t-CNF nanocomposites are characterized by XRD, FTIR, SEM, AFM and TEM. • Electrical conductivity was achieved by epoxy with a threshold at 1 wt% of t-CNF. • Tensile strength is enhanced by 40% due to dispersion of t-CNF. • Synthesized nanocomposites are suitable for fabricating electronic devises.

Thermo-curable epoxy systems for nanoimprint lithography

International Nuclear Information System (INIS)

Wu, Chun-Chang; Hsu, Steve Lien-Chung

2010-01-01

In this work, we have used solvent-free thermo-curable epoxy systems for low-pressure and moderate-temperature nanoimprint lithography (NIL). The curing kinetic parameters and conversion of diglycidyl ether of bisphenol A (DGEBA) resin with different ambient-cure 930 and 954 hardeners were studied by the isothermal DSC technique. They are useful for the study of epoxy resins in the imprinting application. The DGEBA/930 and DGEBA/954 epoxy resists can be imprinted to obtain high-density nano- and micro-scale patterns on a flexible indium tin oxide/poly(ethylene terephthalate) (ITO/PET) substrate. The DGEBA/930 epoxy resin is not only suitable for resist material, but also for plastic mold material. Highly dense nanometer patterns can be successfully imprinted using a UV-curable resist from the DGEBA/930 epoxy mold. Using the replicated DGEBA/930 epoxy mold instead of the expensive master can prevent brittle failure of the silicon molds in the NIL

Fatigue life extension of epoxy materials using ultrafast epoxy-SbF5 healing system introduced by manual infiltration

Directory of Open Access Journals (Sweden)

X. J. Ye

2015-03-01

Full Text Available The present paper is devoted to the verification of the capability of epoxy-SbF5 system as a healing chemistry for rapidly retarding and/or arresting fatigue cracks in epoxy materials at room temperature. Owing to the very fast curing speed of epoxy catalyzed by SbF5, epoxy monomer and the hardener (ethanol solution of SbF5–ethanol complex are successively infiltrated into the fracture plane under cyclic loading during the tension-tension fatigue test. As a result, the mechanisms including hydrodynamic pressure crack tip shielding, polymeric wedge and adhesive bonding of the healing agent are revealed. It is found that the healing agent forms solidified wedge at the crack tip within 20 s after start of polymerization of the epoxy monomer, so that the highest healing effect is offered at the moment. The epoxy-SbF5 system proves to be effective in rapidly obstructing fatigue crack propagation (despite that its cured version has lower fracture toughness than the matrix, and satisfies the requirement of constructing fast self-healing polymeric materials.

A composite thin vacuum window for the CLAS photon tagger at Jefferson lab

International Nuclear Information System (INIS)

Matthews, S.K.; Crannell, Hall; O'Brien, J.T.; Sober, D.I.

1999-01-01

The construction of a thin vacuum window, currently in use on the CLAS photon tagging system at the Thomas Jefferson National Accelerator Facility, is described. A layer of woven Kevlar cloth supports a much thinner membrane of aluminized Mylar. Notable features of this particular window include its overall length (9.6 m), and the fact that the entire load is supported by the epoxy seal with no mechanical clamping around the edges. Results from a diverse program of materials testing, including a clear dependence of leak rate on relative humidity, are also reported

A composite thin vacuum window for the CLAS photon tagger at Jefferson lab

CERN Document Server

Matthews, S K; O'Brien, J T; Sober, D I

1999-01-01

The construction of a thin vacuum window, currently in use on the CLAS photon tagging system at the Thomas Jefferson National Accelerator Facility, is described. A layer of woven Kevlar cloth supports a much thinner membrane of aluminized Mylar. Notable features of this particular window include its overall length (9.6 m), and the fact that the entire load is supported by the epoxy seal with no mechanical clamping around the edges. Results from a diverse program of materials testing, including a clear dependence of leak rate on relative humidity, are also reported.

Supercritical CO2 impregnation of polyethylene components for medical purposes

Directory of Open Access Journals (Sweden)

Gamse Thomas

2007-01-01

Full Text Available Modem hip and knee endoprosthesis are produced in titanium and to reduce the friction at the contact area polymer parts, mainly ultra-high molecular weight polyethylene (UHMW-PE, are installed. The polyethylene is impregnated with a-tocopherol (vitamin E before processing for remarkable decrease of oxidative degradation. Cross linked UHMW-PE offers much higher stability, but a-tocopherol cannot be added before processing, because a-tocopherol hinders the cross linking process accompanied by a heavy degradation of the vitamin. The impregnation of UHMW-PE with a-tocopherol has to be performed after the cross linking process and an accurate concentration has to be achieved over the cross section of the whole material. In the first tests UHMW-PE-cubes were stored in pure a-tocopherol under inert atmosphere at temperatures from 100 to 150 °C resulting in a high mass fraction of a-tocopherol in the edge zones and no constant concentration over the cross section. For better distribution and for regulating the mass fraction of a-tocopherol in the cross linked UHMW-PE material supercritical CO2 impregnation tests were investigated. Again UHMW-PE-cubes were impregnated in an autoclave with a-tocopherol dissolved in supercritical CO2 at different pressures and temperatures with variable impregnation times and vitamin E concentrations. Based on the excellent results of supercritical CO2 impregnation standard hip and knee cups were stabilized nearly homogeneously with varying mass fraction of a-tocopherol.

Design and Analysis of Drive Shaft using Kevlar/Epoxy and Glass/Epoxy as a Composite Material

Science.gov (United States)

Karthikeyan, P.; Gobinath, R.; Kumar, L. Ajith; Jenish, D. Xavier

2017-05-01

In automobile industry drive shaft is one of the most important components to transmit power form the engine to rear wheel through the differential gear. Generally steel drive shaft is used in automobile industry, nowadays they are more interested to replace steel drive shaft with that of composite drive shaft. The overall objective of this paper is to analyze the composite drive shaft using to find out the best replacement for conventional steel drive shaft. The uses of advanced composite materials such as Kevlar, Graphite, Carbon and Glass with proper resins ware resulted in remarkable achievements in automobile industry because of its greater specific strength and specific modulus, improved fatigue and corrosion resistances and reduction in energy requirements due to reduction in weight as compared to steel shaft. This paper is to presents, the modeling and analysis of drive shaft using Kevlar/Epoxy and Glass/Epoxy as a composite material and to find best replacement for conventional steel drive shafts with an Kevlar/epoxy or Glass/Epoxy resin composite drive shaft. Modeling is done using CATIA software and Analysis is carried out by using ANSYS 10.0 software for easy understanding. The composite drive shaft reduces the weight by 81.67 % for Kevlar/Epoxy and 72.66% for Glass/Epoxy when compared with conventional steel drive shaft.

X-ray initiated polymerization of wood impregnants

Energy Technology Data Exchange (ETDEWEB)

Cleland, Marshall R.; Galloway, Richard A. [IBA Industrial, Inc., Edgewood, NY (United States); Berejka, Anthony J. [Ionicorp, Huntington, NY 11743 (United States)], E-mail: berejka@msn.com; Montoney, Daniel [Strathmore Products, Syracuse, NY (United States); Driscoll, Mark; Smith, Leonard; Scott Larsen, L. [State University of New York, SUNY-ESF, Syracuse, NY (United States)

2009-07-15

X-rays, derived from a high energy, high-current electron beam (EB), initiated in-situ polymerization of a unique class of monomers that were found to penetrate the cell walls of wood. X-rays initiated an auto-catalytic acrylic polymerization and penetrated through thick pieces of wood. The final cured product having the polymerizate, a polymer, both in the wood cell lumens and in the cell walls is called wood impregnated with a wood-polymer penetrant (WPP). The controlled lower dose rate of X-rays overcame disproportionation encountered when using higher dose-rate electron beam initiation. With X-rays, the in-situ polymerization took place in one exposure of modest dose. With EB, multiple passes were needed to avoid excessive heat build-up and monomer volatilization. Having entered the cell walls of the wood and then being polymerized within the cell walls, these radiation-cured unique monomers imparted outstanding dimensional stability upon exposure of the impregnated wood to humidity cycling. The preferred monomer system was also chemically modified prior to impregnation with agents that would remain in the wood and prevent the growth of fungi and other microbials. This technique differs from historic uses of monomers that merely filled the lumens of the wood (historic wood-polymer composites), which are only suitable for indoor use. The WPP impregnated wood that was either X-ray cured or EB cured demonstrated enhanced structural properties, dimensional stability, and decay resistance.

X-ray initiated polymerization of wood impregnants

International Nuclear Information System (INIS)

Cleland, Marshall R.; Galloway, Richard A.; Berejka, Anthony J.; Montoney, Daniel; Driscoll, Mark; Smith, Leonard; Scott Larsen, L.

2009-01-01

X-rays, derived from a high energy, high-current electron beam (EB), initiated in-situ polymerization of a unique class of monomers that were found to penetrate the cell walls of wood. X-rays initiated an auto-catalytic acrylic polymerization and penetrated through thick pieces of wood. The final cured product having the polymerizate, a polymer, both in the wood cell lumens and in the cell walls is called wood impregnated with a wood-polymer penetrant (WPP). The controlled lower dose rate of X-rays overcame disproportionation encountered when using higher dose-rate electron beam initiation. With X-rays, the in-situ polymerization took place in one exposure of modest dose. With EB, multiple passes were needed to avoid excessive heat build-up and monomer volatilization. Having entered the cell walls of the wood and then being polymerized within the cell walls, these radiation-cured unique monomers imparted outstanding dimensional stability upon exposure of the impregnated wood to humidity cycling. The preferred monomer system was also chemically modified prior to impregnation with agents that would remain in the wood and prevent the growth of fungi and other microbials. This technique differs from historic uses of monomers that merely filled the lumens of the wood (historic wood-polymer composites), which are only suitable for indoor use. The WPP impregnated wood that was either X-ray cured or EB cured demonstrated enhanced structural properties, dimensional stability, and decay resistance.

Polymer-filled microcontainers for oral delivery loaded using supercritical impregnation

DEFF Research Database (Denmark)

Marizza, Paolo; Keller, Stephan Sylvest; Müllertz, Anette

2014-01-01

with a quasi-no-waste performance. Then ketoprofen is impregnated in the polymer matrix by using supercritical carbon dioxide (scCO2) as loading medium. The amount of polymer is controlled by the volume and the number of droplets of dispensed polymer and drug loading is tuned by varying the impregnation...... procedures. This work proposes an effective loading technique for a poorly soluble model drug in microcontainers, by combining inkjet printing and supercritical fluid impregnation. Well defined quantities of poly(vinyl pyrrolidone) (PVP) solutions are dispensed into microcontainers by inkjet printing...

Comparison of structural health assessment capabilities in epoxy – carbon black and epoxy – carbon nanotube nanocomposites

Directory of Open Access Journals (Sweden)

F. Inam

2014-01-01

Full Text Available A novel method for comparing structural health of different types of brittle epoxy nanocomposites filled with carbon nanostructured fillers is presented. Epoxy – 0.2 vol% carbon black (CB and epoxy – 0.2 vol% carbon nanotube (CNT nanocomposite bars were prepared by calendering and thermal curing. Nanocomposite bars were subjected to Vickers diamond indentation to produce sub-surface damage. Electrical conductivities were analysed by 4-point method to estimate the structural damage caused by indentation. For comprehensive comparison, fracture toughness and percolation threshold were analysed as well. Because of the systematically induced indentation damage, a sharp decrease of 89% was observed in the electrical conductivity of epoxy – CNT nanocomposite as compared to 25% in the electrical conductivity of epoxy – CB nanocomposite. CNTs impart superior damage sensing capability in brittle nanocomposite structures, in comparison to CB, due to their high aspect ratio (fibrous nature and high electrical conductivity.

Fracture behavior of α-zirconium phosphate-based epoxy nanocomposites

International Nuclear Information System (INIS)

Sue, H.-J.; Gam, K.T.; Bestaoui, N.; Clearfield, A.; Miyamoto, M.; Miyatake, N.

2004-01-01

The fracture behaviors of α-zirconium phosphate (α-ZrP) based epoxy nanocomposites, with and without core-shell rubber (CSR) toughening, were investigated. The state of exfoliation and dispersion of α-ZrP nanofiller in epoxy were characterized using X-ray scattering and various microscopy tools. The level of enhancement in storage moduli of epoxy nanocomposite against neat epoxy is found to depend on the state of exfoliation of α-ZrP as well as the damping characteristics of the epoxy matrix. The fracture process in epoxy nanocomposite is dominated by preferred crack propagation along the weak intercalated α-ZrP interfaces, and the presence of α-ZrP does not alter the fracture toughness of the epoxy matrix. However, the toughening using CSR can significantly improve the fracture toughness of the nanocomposite. The fracture mechanisms responsible for such a toughening effect in CSR-toughened epoxy nanocomposite are rubber particle cavitation, followed by shear banding of epoxy matrix. The ductility and toughenability of epoxy do not appear to be affected by the incorporation of α-ZrP. Approaches for producing toughened high performance polymer nanocomposites are discussed

Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

Directory of Open Access Journals (Sweden)

Raman P. Singh

2010-01-01

Full Text Available This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

International Nuclear Information System (INIS)

Singh, R.P.; Zunjarrao, S.C.; Pandey, G.; Khait, M.; Korach, C.S.

2010-01-01

This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

Carbonization of heavy metal impregnated sewage sludge oriented towards potential co-disposal

Energy Technology Data Exchange (ETDEWEB)

Dou, Xiaomin [Thermal & Environmental Engineering Institute, Tongji University, Shanghai 201804 (China); Chen, Dezhen, E-mail: chendezhen@tongji.edu.cn [Thermal & Environmental Engineering Institute, Tongji University, Shanghai 201804 (China); Hu, Yuyan; Feng, Yuheng [Thermal & Environmental Engineering Institute, Tongji University, Shanghai 201804 (China); Dai, Xiaohu [National Engineering Research Centre for Urban Pollution Control, Tongji University, Shanghai 200092 (China); College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

2017-01-05

Highlights: • The carbonization of SS with externally impregnated heavy metals was investigated. • Externally impregnated heavy metals can be immobilized in the SSC. • Higher carbonization temperature help produce non-hazardous SSC. • Incineration FA can be kneaded into SS for co-disposal through co-carbonization. - Abstract: Sewage sludge (SS) is adopted as a stabilizer to immobilize externally impregnated heavy metals through carbonization oriented towards the co-disposal of SS and some hazardous wastes. Firstly Cu and Pb were impregnated into SS to ascertain the impregnating capacity and leaching behaviours of heavy metals in the resulting sewage sludge char (SSC). Meanwhile, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the heavy metal phase in the SSC. The results showed that within 400–800 °C and an impregnating concentration ≨0.5 wt%, more than 90% of the externally impregnated Cu and Pb were remained in the SSC and immobilized. And higher temperatures helped produce non-hazardous SSC. In addition, SEM and XRD analyses revealed that externally impregnated heavy metals could be converted into stable forms and evenly distributed throughout the SSC. In the second step municipal solid waste incineration fly ash (FA) was kneaded into SS and subjected to carbonization; it has been proved that the heavy metals in FA can be well immobilized in the resulting char when FA: SS mass ratio is 1:5. Those results show that sewage sludge can be co-carbonized with wastes contaminated with heavy metals to achieve co-disposal.

Carbonization of heavy metal impregnated sewage sludge oriented towards potential co-disposal

International Nuclear Information System (INIS)

Dou, Xiaomin; Chen, Dezhen; Hu, Yuyan; Feng, Yuheng; Dai, Xiaohu

2017-01-01

Highlights: • The carbonization of SS with externally impregnated heavy metals was investigated. • Externally impregnated heavy metals can be immobilized in the SSC. • Higher carbonization temperature help produce non-hazardous SSC. • Incineration FA can be kneaded into SS for co-disposal through co-carbonization. - Abstract: Sewage sludge (SS) is adopted as a stabilizer to immobilize externally impregnated heavy metals through carbonization oriented towards the co-disposal of SS and some hazardous wastes. Firstly Cu and Pb were impregnated into SS to ascertain the impregnating capacity and leaching behaviours of heavy metals in the resulting sewage sludge char (SSC). Meanwhile, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the heavy metal phase in the SSC. The results showed that within 400–800 °C and an impregnating concentration ≨0.5 wt%, more than 90% of the externally impregnated Cu and Pb were remained in the SSC and immobilized. And higher temperatures helped produce non-hazardous SSC. In addition, SEM and XRD analyses revealed that externally impregnated heavy metals could be converted into stable forms and evenly distributed throughout the SSC. In the second step municipal solid waste incineration fly ash (FA) was kneaded into SS and subjected to carbonization; it has been proved that the heavy metals in FA can be well immobilized in the resulting char when FA: SS mass ratio is 1:5. Those results show that sewage sludge can be co-carbonized with wastes contaminated with heavy metals to achieve co-disposal.

Occupational exposure to epoxy resins

NARCIS (Netherlands)

Terwoert, J.; Kersting, K.

2014-01-01

Products based on epoxy resins as a binder have become popular in various settings, among which the construction industry and in windmill blade production, as a result of their excellent technical properties. However, due to the same properties epoxy products are a notorious cause of allergic skin

Lead oxide-decorated graphene oxide/epoxy composite towards X-Ray radiation shielding

Science.gov (United States)

Hashemi, Seyyed Alireza; Mousavi, Seyyed Mojtaba; Faghihi, Reza; Arjmand, Mohammad; Sina, Sedigheh; Amani, Ali Mohammad

2018-05-01

In this study, employing modified Hummers method coupled with a multi-stage manufacturing procedure, graphene oxide (GO) decorated with Pb3O4 (GO-Pb3O4) at different weight ratios was synthesized. Thereupon, via the vacuum shock technique, composites holding GO-Pb3O4 at different filler loadings (5 and 10 wt%) and thicknesses (4 and 6 mm) were fabricated. Successful decoration of GO with Pb3O4 was confirmed via FTIR analysis. Moreover, particle size distribution of the produced fillers was examined using particle size analyzer. X-ray attenuation examination revealed that reinforcement of epoxy-based composites with GO-Pb3O4 led to a significant improvement in the overall attenuation rate of X-ray beam. For instance, composites containing 10 wt% GO-Pb3O4 with 6 mm thickness showed 4.06, 4.83 and 3.91 mm equivalent aluminum thickness at 40, 60 and 80 kVp energies, denoting 124.3, 124.6 and 103.6% improvement in the X-ray attenuation rate compared to a sample holding neat epoxy resin, respectively. Simulation results revealed that the effect of GO-Pb3O4 loading on the X-ray shielding performance undermined with increase in the voltage of the applied X-ray beam.

Comparison of structural health assessment capabilities in epoxy – carbon black and epoxy – carbon nanotube nanocomposites

OpenAIRE

F. Inam; B. R. Bhat; N. Luhyna; T. Vo

2014-01-01

A novel method for comparing structural health of different types of brittle epoxy nanocomposites filled with carbon nanostructured fillers is presented. Epoxy – 0.2 vol% carbon black (CB) and epoxy – 0.2 vol% carbon nanotube (CNT) nanocomposite bars were prepared by calendering and thermal curing. Nanocomposite bars were subjected to Vickers diamond indentation to produce sub-surface damage. Electrical conductivities were analysed by 4-point method to estimate the structural damage caused by...

Evaluation of Out-of-Autoclave (OOA epoxy system

Directory of Open Access Journals (Sweden)

Fernanda Guilherme

Full Text Available Abstract Epoxy resins (EP usually cure in autoclave to minimize resin voids and to achieve the desired resin/fiber ratio. Cure parameters such as temperature, vacuum and pressure levels are controlled and monitored. Aiming time and cost optimization, new out-of-autoclave (OOA cure processes have been developed lately. This study evaluated the cure cycle and the effect of non-programmed interruptions in an OOA process. Fourier Transform Infrared spectroscopy (FT-IR results show similarities between the resin used and diglycidyl ether of bisphenol A (DGEBA and also that the curing system is composed of cyan and sulfur hardeners, codified in industry, as Components of #2511 Resin System. The cure cycle and its interruptions were simulated by dynamic-mechanical analysis (DMA. The samples obtained were evaluated by FT-IR and differential scanning calorimetry (DSC, whose results show that the degree of cure varying between 0.8 to 0.85 was achieved at 120 °C.

Biobased Epoxy Nanocomposites Derived from Lignin-Based Monomers.

Science.gov (United States)

Zhao, Shou; Abu-Omar, Mahdi M

2015-07-13

Biobased epoxy nanocomposites were synthesized based on 2-methoxy-4-propylphenol (dihydroeugenol, DHE), a molecule that has been obtained from the lignin component of biomass. To increase the content of hydroxyl groups, DHE was o-demethylated using aqueous HBr to yield propylcatechol (DHEO), which was subsequently glycidylated to epoxy monomer. Optimal conditions in terms of yield and epoxy equivalent weight were found to be 60 °C with equal NaOH/phenolic hydroxyl molar ratio. The structural evolution from DHE to cured epoxy was followed by (1)H NMR and Fourier transform infrared spectroscopy. The nano-montmorillonite modified DHEO epoxy exhibited improved storage modulus and thermal stability as determined from dynamic mechanical analysis and thermogravimetric analysis. This study widens the synthesis routes of biobased epoxy thermosets from lignin-based molecules.

Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

Science.gov (United States)

Fasanella, Nicholas; Sundararaghavan, Veera

2015-09-01

Molecular dynamics simulations are performed to compute thermomechanical properties of cured epoxy resins reinforced with pristine and covalently functionalized carbon nanotubes. A DGEBA-DDS epoxy network was built using the ‘dendrimer’ growth approach where 75% of available epoxy sites were cross-linked. The epoxy model is verified through comparisons to experiments, and simulations are performed on nanotube reinforced cross-linked epoxy matrix using the CVFF force field in LAMMPS. Full stiffness matrices and linear coefficient of thermal expansion vectors are obtained for the nanocomposite. Large increases in stiffness and large decreases in thermal expansion were seen along the direction of the nanotube for both nanocomposite systems when compared to neat epoxy. The direction transverse to nanotube saw a 40% increase in stiffness due to covalent functionalization over neat epoxy at 1 K whereas the pristine nanotube system only saw a 7% increase due to van der Waals effects. The functionalized SWNT/epoxy nanocomposite showed an additional 42% decrease in thermal expansion along the nanotube direction when compared to the pristine SWNT/epoxy nanocomposite. The stiffness matrices are rotated over every possible orientation to simulate the effects of an isotropic system of randomly oriented nanotubes in the epoxy. The randomly oriented covalently functionalized SWNT/Epoxy nanocomposites showed substantial improvements over the plain epoxy in terms of higher stiffness (200% increase) and lower thermal expansion (32% reduction). Through MD simulations, we develop means to build simulation cells, perform annealing to reach correct densities, compute thermomechanical properties and compare with experiments.

Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

International Nuclear Information System (INIS)

Fasanella, Nicholas; Sundararaghavan, Veera

2015-01-01

Molecular dynamics simulations are performed to compute thermomechanical properties of cured epoxy resins reinforced with pristine and covalently functionalized carbon nanotubes. A DGEBA-DDS epoxy network was built using the ‘dendrimer’ growth approach where 75% of available epoxy sites were cross-linked. The epoxy model is verified through comparisons to experiments, and simulations are performed on nanotube reinforced cross-linked epoxy matrix using the CVFF force field in LAMMPS. Full stiffness matrices and linear coefficient of thermal expansion vectors are obtained for the nanocomposite. Large increases in stiffness and large decreases in thermal expansion were seen along the direction of the nanotube for both nanocomposite systems when compared to neat epoxy. The direction transverse to nanotube saw a 40% increase in stiffness due to covalent functionalization over neat epoxy at 1 K whereas the pristine nanotube system only saw a 7% increase due to van der Waals effects. The functionalized SWNT/epoxy nanocomposite showed an additional 42% decrease in thermal expansion along the nanotube direction when compared to the pristine SWNT/epoxy nanocomposite. The stiffness matrices are rotated over every possible orientation to simulate the effects of an isotropic system of randomly oriented nanotubes in the epoxy. The randomly oriented covalently functionalized SWNT/Epoxy nanocomposites showed substantial improvements over the plain epoxy in terms of higher stiffness (200% increase) and lower thermal expansion (32% reduction). Through MD simulations, we develop means to build simulation cells, perform annealing to reach correct densities, compute thermomechanical properties and compare with experiments. (paper)

Vacuum infusion method for woven carbon/Kevlar reinforced hybrid composite

Science.gov (United States)

Hashim, N.; Majid, D. L.; Uda, N.; Zahari, R.; Yidris, N.

2017-12-01

The vacuum assisted resin transfer moulding (VaRTM) or Vacuum Infusion (VI) is one of the fabrication methods used for composite materials. Compared to other methods, this process costs lower than using prepregs because it does not need to use the autoclave to cure. Moreover, composites fabricated using this VI method exhibit superior mechanical properties than those made through hand layup process. In this study, the VI method is used in fabricating woven carbon/Kevlar fibre cloth with epoxy matrix. This paper reports the detailed methods on fabricating the hybrid composite using VI process and several precautions that need to be taken to avoid any damage to the properties of the composite material. The result highlights that the successfully fabricated composite has approximately 60% of fibres weight fraction. Since the composites produced by the VI process have a higher fibre percentage, this process should be considered for composites used in applications that are susceptible to the conditions where the fibres need to be the dominant element such as in tension loading.

Studies of properties of rubber wood with impregnation of polymer

Indian Academy of Sciences (India)

Impregnation of rubber wood has been carried out under different conditions by using styrene as grafting monomer and glycidyl methacrylate (GMA) as crosslinker. Properties such as dimensional stability, water absorption, hardness, tensile strength, flexural strength, etc of the impregnated wood have been checked and ...

Evaluation of Impact Strength of Epoxy Based Hybrid Composites Reinforced with E-Glass/Kevlar 49

Directory of Open Access Journals (Sweden)

SUBHAN ALIJOGI

2017-10-01

Full Text Available In hybridization different fibers are stacked layer by layer to produce laminates have specific strength and stiffness and employed in light weight high strength applications. Physically mean fabricated hybrid composites used in aerospace, under water, body armors and armed forces establishment. In present work drop-weight impact response of hybrid composites were investigated by making laminates of hybrid composites. In Hybridization layers of E-glass (roving and Kevlar 49 fabrics stacked with epoxy resin. The layers formulation was set up by hand layup method. Impregnationsof epoxy resin of commercial grade (601A in fabrics were accomplished by VRTM (Vacuum Bagging Resin Transfer Molding technique. Layup placementof Glass fibers/ Kevlar at 0°/90°, 45°/45° and 30°/60° were set for this work. Mechanical properties such as impact strength, bear resistance and break resistance were analyzed by usingASTM D-256 and D-3763 standard.Experimental investigation was conducted using instrumented Dart impact and Izod Impact test. E-glass/Kevlar 49 at layup 0°/90°and 30°/60°exhibited improvedimpact strength than 45°/45°. The surface morphology and fractography were also investigated by capturing different images of Specimens by using the SEM (Scanning Electron Microscopy. The fiberreinforcement and matrix fracture were also observed by using SEM.The SEM images suggest that epoxy resin tightly bonded with Kevlar fibers whereas Glass fibers were pulled out from laminations.

Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

Science.gov (United States)

Patel, Binay S.

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

Preparation of iron-impregnated granular activated carbon for arsenic removal from drinking water

International Nuclear Information System (INIS)

Chang Qigang; Lin Wei; Ying Weichi

2010-01-01

Granular activated carbon (GAC) was impregnated with iron through a new multi-step procedure using ferrous chloride as the precursor for removing arsenic from drinking water. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis demonstrated that the impregnated iron was distributed evenly on the internal surface of the GAC. Impregnated iron formed nano-size particles, and existed in both crystalline (akaganeite) and amorphous iron forms. Iron-impregnated GACs (Fe-GACs) were treated with sodium hydroxide to stabilize iron in GAC and impregnated iron was found very stable at the common pH range in water treatments. Synthetic arsenate-contaminated drinking water was used in isotherm tests to evaluate arsenic adsorption capacities and iron use efficiencies of Fe-GACs with iron contents ranging from 1.64% to 12.13% (by weight). Nonlinear regression was used to obtain unbiased estimates of Langmuir model parameters. The arsenic adsorption capacity of Fe-GAC increased significantly with impregnated iron up to 4.22% and then decreased with more impregnated iron. Fe-GACs synthesized in this study exhibited higher affinity for arsenate as compared with references in literature and shows great potential for real implementations.

Mechanical properties of graphene oxide (GO/epoxy composites

Directory of Open Access Journals (Sweden)

Shivan Ismael Abdullah

2015-08-01

Full Text Available In this study, the effects of graphene oxide (GO on composites based on epoxy resin were analyzed. Different contents of GO (1.5–6 vol.% were added to epoxy resin. The GO/epoxy composite was prepared using the casting method and was prepared under room temperature. Mechanical tests’ results such as tensile test, impact test and hardness test show enhancements of the mechanical properties of the GO/epoxy composite. The experimental results clearly show an improvement in the Young’s modulus, tensile strength and hardness. The impact strength was seen to decrease, pointing to brittleness increase of the GO/epoxy composite. A microstructure analysis using Scanning Electron Microscopy (SEM and X-ray diffraction (XRD analysis was also performed, which showed how GO impeded the propagation of cracks in the composite. From the SEM images we observed the interface between the GO and the epoxy composite. As can be seen from this research, the GO/epoxy composites can be used for a large number of applications. The results of this research are a strong evidence for GO/epoxy composites being a potential candidate for use in a variety of industrial applications, especially for automobile parts, aircraft components, and electronic parts such as supercapacitors, transistors, etc.

The effect of type and mixture of resin on the properties of impregnated paper

Directory of Open Access Journals (Sweden)

hossein Kermanian

2017-05-01

Full Text Available This study was carried out in order to investigate the effects of different types of resins and also their mixtures on the impregnated paper properties. In this regard, pure urea resin (100%, mixture of melamine and urea resins with various combinations (60/40 and 70/30 and 50/50, mixture of nano-fiber cellulose ratios of 1, 2 and 3 percent with urea resin and pure PVA (100% were used to impregnate of newsprint basic paper of Mazandaran wood and paper industries. Immersion of samples in the impregnation step were done in two time of 5 and 10 seconds. Next, melamine resin was used for surface coating and then absorption of resin in the impregnation and coating process measured. Results showed that in the impregnation step with pure urea (100%, in the respect of absorption rate and surface properties of melamine paper, the best time of impregnation was obtained 10 seconds. In the combined treatment, adding up to 30% melamine to urea resin, as impregnation step resin, offers better properties in terms of stain resistance, cigarette resistance, resistance to cracking and resistance to hot water steam for impregnatedmade paper. By adding nanocellulose up to 1% in impregnation resin, better properties is obtained for melamine paper. Also, PVA as impregnation resin, can be offer similar quality to pure urea in the resulting melamine papers.

Evaluation and control of poisoning of impregnated carbons used for organic iodide removal

International Nuclear Information System (INIS)

Kovach, J.L.; Rankovic, L.

1979-01-01

By the evaluation of the chemical reactions which have taken place on impregnated activated carbon surfaces exposed to nuclear reactor atmospheric environments, the role of various impregnants has been studied. The evaluation shows several different paths for the aging and posioning to take place. The four major causes were found to be: organic solvent contamination; inorganic acid gas contamination; formation of organic acids on carbon surface; and, formation of SO 2 from carbon sulfur content. Prevention of poisoning by the first two paths can be accomplished only by procedural changes within the facility. However the last three poisoning paths can be controlled to some extent by the selection of carbon pretreatment techniques and the type of impregnant used. Results were generated by evaluating used carbons from 14 nuclear power plants and by artificial poisoning of laboratory impregnated carbons. Impregnants which have antioxidant properties, besides reaction with organic iodides, can increase the life of the impregnated activated carbons

Starch-modified magnetite nanoparticles for impregnation into cartilage

Energy Technology Data Exchange (ETDEWEB)

Soshnikova, Yulia M., E-mail: yuliasoshnikova@gmail.com [Russian Academy of Sciences, Institute on Laser and Information Technologies (Russian Federation); Roman, Svetlana G.; Chebotareva, Natalia A. [A.N. Bach Institute of Biochemistry (Russian Federation); Baum, Olga I. [Russian Academy of Sciences, Institute on Laser and Information Technologies (Russian Federation); Obrezkova, Mariya V. [Lomonosov Moscow State University, Department of Chemistry (Russian Federation); Gillis, Richard B.; Harding, Stephen E. [University of Nottingham, National Centre for Macromolecular Hydrodynamics (United Kingdom); Sobol, Emil N. [Russian Academy of Sciences, Institute on Laser and Information Technologies (Russian Federation); Lunin, Valeriy V. [Lomonosov Moscow State University, Department of Chemistry (Russian Federation)

2013-11-15

The paper presents preparation and characterization of starch-modified Fe{sub 3}O{sub 4} nanoparticles (NPs) in aqueous dispersion after impregnation into healthy and damaged types of cartilage. We show that starch-modified dispersion has a narrower size distribution than a non‐stabilized one. The average hydrodynamic radius of magnetite NPs in a dispersion used for impregnation into cartilage is (48 ± 1) nm with the width of the distribution from 5 to 200 nm. We investigate stability of aqueous magnetite NPs dispersions during storage and with increase in temperature (up to 70 °C). We find that polydisperse magnetite NPs can penetrate into cartilage and the size and concentration of impregnated particles depend on the organization of the tissue structure. The results confirm the possibility of application of magnetite NPs in diagnostics and laser treatment of degenerative cartilage deceases.

Epoxy resin systems for FGD units

International Nuclear Information System (INIS)

Brytus, V.; Puglisi, J.S.

1984-01-01

This paper discusses ongoing research work which is directed towards epoxy resins and curing agents which are designed to withstand aggressive environments. This work includes not only a chemical description of the materials involved, but the application testing necessary to verify the usefulness of these systems. It demonstrates that new high performance epoxy systems are superior to those which traditionally come to mind when one thinks epoxy. Finally, it discusses the results of testing designed specifically to screen candidates for use in FGD units

A kinetic study of pyrolysis in pitch impregnated electrodes

Energy Technology Data Exchange (ETDEWEB)

Kocaefe, D.; Charette, A.; Ferland, J.; Couderc, P.; Saint-Romain, J.L. (Universite du Quebec a Chicoutini, Chicoutini, PQ (Canada))

1990-12-01

A study was conducted on carbon electrodes which were impregnated with three different pitches. The focus of the study was to investigate the pyrolysis of pitch impregnated electrodes. For the purposes of the research an experimental technique and calculation procedure were developed. A kinetic model was used to interpret the data, comparison of model predictions and experimental data showed good agreement. 17 refs., 10 figs., 2 tabs.

Enhancement of mechanical properties of epoxy/graphene nanocomposite

Science.gov (United States)

Berhanuddin, N. I. C.; Zaman, I.; Rozlan, S. A. M.; Karim, M. A. A.; Manshoor, B.; Khalid, A.; Chan, S. W.; Meng, Q.

2017-10-01

Graphene is a novel class of nanofillers possessing outstanding characteristics including most compatible with most polymers, high absolute strength, high aspect ratio and cost effectiveness. In this study, graphene was used to reinforce epoxy as a matrix, to enhance its mechanical properties. Two types of epoxy composite were developed which are epoxy/graphene nanocomposite and epoxy/modified graphene nanocomposite. The fabrication of graphene was going through thermal expansion and sonication process. Chemical modification was only done for modified graphene where 4,4’-Methylene diphenyl diisocyanate (MDI) is used. The mechanical properties of both nanocomposite, such as Young’s modulus and maximum stress were investigated. Three weight percentage were used for this study which are 0.5 wt%, 1.0 wt% and 1.5 wt%. At 0.5 wt%, modified and unmodified shows the highest value compared to neat epoxy, where the value were 8 GPa, 6 GPa and 0.675 GPa, respectively. For maximum stress, neat epoxy showed the best result compared to both nanocomposite due to the changes of material properties when adding the filler into the matrix. Therefore, both nanocomposite increase the mechanical properties of the epoxy, however modification surface of graphene gives better improvement.

Adhesion between coating layers based on epoxy and silicone

DEFF Research Database (Denmark)

Svendsen, Jacob R.; Kontogeorgis, Georgios; Kiil, Søren

2007-01-01

The adhesion between a silicon tie-coat and epoxy primers, used in marine coating systems, has been studied in this work. Six epoxy coatings (with varying chain lengths of the epoxy resins), some of which have shown problems with adhesion to the tie-coat during service life, have been considered....... The experimental investigation includes measurements of the surface tension of the tie-coat and the critical surface tensions of the epoxies, topographic investigation of the surfaces of cured epoxy coatings via atomic force microscopy (AFM), and pull-off tests for investigating the strength of adhesion...... to the silicon/epoxy systems. Calculations for determining the roughness factor of the six epoxy coatings (based on the AFM topographies) and the theoretical work of adhesion have been carried out. The coating surfaces are also characterized based on the van Oss-Good theory. Previous studies on the modulus...

Carbonization of heavy metal impregnated sewage sludge oriented towards potential co-disposal.

Science.gov (United States)

Dou, Xiaomin; Chen, Dezhen; Hu, Yuyan; Feng, Yuheng; Dai, Xiaohu

2017-01-05

Sewage sludge (SS) is adopted as a stabilizer to immobilize externally impregnated heavy metals through carbonization oriented towards the co-disposal of SS and some hazardous wastes. Firstly Cu and Pb were impregnated into SS to ascertain the impregnating capacity and leaching behaviours of heavy metals in the resulting sewage sludge char (SSC). Meanwhile, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the heavy metal phase in the SSC. The results showed that within 400-800°C and an impregnating concentration ≨0.5wt%, more than 90% of the externally impregnated Cu and Pb were remained in the SSC and immobilized. And higher temperatures helped produce non-hazardous SSC. In addition, SEM and XRD analyses revealed that externally impregnated heavy metals could be converted into stable forms and evenly distributed throughout the SSC. In the second step municipal solid waste incineration fly ash (FA) was kneaded into SS and subjected to carbonization; it has been proved that the heavy metals in FA can be well immobilized in the resulting char when FA: SS mass ratio is 1:5. Those results show that sewage sludge can be co-carbonized with wastes contaminated with heavy metals to achieve co-disposal. Copyright © 2016 Elsevier B.V. All rights reserved.

Modification of (DGEBA epoxy resin with maleated depolymerised natural rubber

Directory of Open Access Journals (Sweden)

2008-04-01

Full Text Available In this work, diglycidyl ether of bisphenol A (DEGBA type epoxy resin has been modified with maleated depolymerised natural rubber (MDPR. MDPR was prepared by grafting maleic anhydride onto depolymerised natural rubber. MDPR has been characterized by Fourier transform infrared (FT-IR spectroscopy and nuclear magnetic resonance spectroscopy. MDPR was blended with epoxy resin at three different ratios (97/3, 98/2 and 99/1, by keeping the epoxy resin component as the major phase and maleated depolymerised natural rubber component as the minor phase. The reaction between the two blend components took place between the acid/anhydride group in the MDPR and the epoxide group of the epoxy resin. The proposed reaction schemes were supported by the FT-IR spectrum of the uncured Epoxy/MDPR blends. The neat epoxy resin and Epoxy/MDPR blends were cured by methylene dianiline (DDM at 100°C for three hours. Thermal, morphological and mechanical properties of the neat epoxy and the blends were investigated. Free volume studies of the cured, neat epoxy and Epoxy/MDPR blends were correlated with the morphological and mechanical properties of the same systems using Positron Annihilation Lifetime Studies.

Mercury adsorption properties of sulfur-impregnated adsorbents

Science.gov (United States)

Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

2002-01-01

Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

Drug smuggling using clothing impregnated with cocaine.

Science.gov (United States)

McDermott, Seán D; Power, John D

2005-11-01

A case study is presented where a woman travelling from South America to the Republic of Ireland was detained at Dublin Airport and articles of clothing she had in her luggage were found to be impregnated with cocaine. The study shows that the amount of powder recovered from the garments was approximately 14% of the total weight of the garments. The cocaine was in the form of cocaine hydrochloride and the purity was approximately 80%. An examination of the garments under filtered light highlighted the areas exposed to cocaine and indicated that the method of impregnation was by pouring liquid containing cocaine onto the clothing.

Simulation of the Vacuum Assisted Resin Transfer Molding (VARTM) process and the development of light-weight composite bridging

Science.gov (United States)

Robinson, Marc J.

A continued desire for increased mobility in the aftermath of natural disasters, or on the battlefield, has lead to the need for improved light-weight bridging solutions. This research investigates the development of a carbon/epoxy composite bridging system to meet the needs for light-weight bridging. The research focuses on two main topics. The first topic is that of processing composite structures and the second is the design and testing of these structures. In recent years the Vacuum Assisted Resin Transfer Molding (VARTM) process has become recognized as a low-cost manufacturing alternative for large Fiber Reinforced Polymer (FRP) composite structures for civil, military, and aerospace applications. The success of the VARTM process (complete wet-out) is very sensitive to the resin injection strategy used and the proper placement of flow distribution materials and inlet and vacuum ports. Predicting the flow front pattern, the time required for infusing a part with resin, and the time required to bleed excess resin at the end of filling, is critical to ensure that the part will become completely impregnated and desired fiber volume fractions achieved prior to the resin gelling (initiation of cure). In order to eliminate costly trial and error experiments to determine the optimal infusion strategy, this research presents a simulation model which considers in-plane flow as well as flow through the thickness of the preform. In addition to resin filling, the current model is able to simulate the bleeding of resin at the end of filling to predict the required bleeding time to reach desired fiber volume fractions for the final part. In addition to processing, the second portion of the dissertation investigates the design and testing of composite bridge deck sections which also serve as short-span bridging for gaps up to 4 m in length. The research focuses on the design of a light-weight core material for bridge decking as well as proof loading of short-span bridge

Action of ionizing radiation on epoxy resins

Energy Technology Data Exchange (ETDEWEB)

Van de Voorde, M. E.

1970-12-01

The resistance of classical and experimental epoxy resins to irradiation was studied. The resistance to irradiation of epoxy resins of diverse compositions as well as the development of resins having a radioresistance that approaches that of certain ceramics are discussed. Sources of irradiation and the techniques of dosimetry used are described. The structures of certain epoxy resins and of hardeners are given. The preparation of these resins and their physical properties is described. The effects of radiation on epoxy resins, as well as conditions of irradiation, and suggested mechanisms for degradation of the irradiated resins are discussed. The relationship between chemical structure of the resins and their physical properties is evaluated. (115 references) (JCB)

Flexural Properties of Activated Carbon Filled Epoxy Nano composites

International Nuclear Information System (INIS)

Khalil, H.P.S.A.; Khalil, H.P.S.A.; Alothman, O.Y.; Paridah, M.T.; Zainudin, E.S.

2014-01-01

Activated carbon (AC) filled epoxy nano composites obtained by mixing the desired amount of nano AC viz., bamboo stem, oil palm empty fruit bunch, and coconut shell from agricultural biomass with the epoxy resin. Flexural properties of activated carbons filled epoxy nano composites with 1 %, and 5 % filler loading were measured. In terms of flexural strength and modulus, a significant increment was observed with addition of 1 % vol and 5 % vol nano-activated carbon as compared to neat epoxy. The effect of activated carbon treated by two chemical agents (potassium hydroxide and phosphoric acid) on the flexural properties of epoxy nano composites were also investigated. Flexural strength of activated carbon-bamboo stem, activated carbon-oil palm, and activated carbon-coconut shell reinforced epoxy nano composites showed almost same value in case of 5 % potassium hydroxide activated carbon. Flexural strength of potassium hydroxide activated carbon-based epoxy nano composites was higher than phosphoric acid activated carbon. The flexural toughness of both the potassium hydroxide and phosphoric acid activated carbon reinforced composites range between 0.79 - 0.92 J. It attributed that developed activated carbon filled epoxy nano composites can be used in different applications. (author)

Evaluation of optimal silver amount for the removal of methyl iodide on silver-impregnated adsorbents

International Nuclear Information System (INIS)

Park, G.I.; Cho, I.H.; Kim, J.H.; Oh, W.Z.

2001-01-01

The adsorption characteristics of methyl iodide generated from the simulated off-gas stream on various adsorbents such as silver-impregnated zeolite (AgX), zeocarbon and activated carbon were investigated. An extensive evaluation was made on the optimal silver impregnation amount for the removal of methyl iodide at temperatures up to 300 deg. C. The degree of adsorption efficiency of methyl iodide on silver-impregnated adsorbent is strongly dependent on impregnation amount and process temperature. A quantitative comparison of adsorption efficiencies on three adsorbents in a fixed bed was investigated. The influence of temperature, methyl iodide concentration and silver impregnation amount on the adsorption efficiency is closely related to the pore characteristics of adsorbents. It shows that the effective impregnation ratio was about 10wt%, based on the degree of silver utilization for the removal of methyl iodide. The practical applicability of silver-impregnated zeolite for the removal of radioiodine generated from the DUPIC process was consequently proposed. (author)

Atomistic Modeling of Thermal Conductivity of Epoxy Nanotube Composites

Science.gov (United States)

Fasanella, Nicholas A.; Sundararaghavan, Veera

2016-05-01

The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for epoxy/single wall carbon nanotube (SWNT) nanocomposites. An epoxy network of DGEBA-DDS was built using the `dendrimer' growth approach, and conductivity was computed by taking into account long-range Coulombic forces via a k-space approach. Thermal conductivity was calculated in the direction perpendicular to, and along the SWNT axis for functionalized and pristine SWNT/epoxy nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. The thermal conductivity of the long, pristine SWNT/epoxy system is equivalent to that of an isolated SWNT along its axis, but there was a 27% reduction perpendicular to the nanotube axis. The functionalized, long SWNT/epoxy system had a very large increase in thermal conductivity along the nanotube axis (~700%), as well as the directions perpendicular to the nanotube (64%). The discontinuous nanotubes displayed an increased thermal conductivity along the SWNT axis compared to neat epoxy (103-115% for the pristine SWNT/epoxy, and 91-103% for functionalized SWNT/epoxy system). The functionalized system also showed a 42% improvement perpendicular to the nanotube, while the pristine SWNT/epoxy system had no improvement over epoxy. The thermal conductivity tensor is averaged over all possible orientations to see the effects of randomly orientated nanotubes, and allow for experimental comparison. Excellent agreement is seen for the discontinuous, pristine SWNT/epoxy nanocomposite. These simulations demonstrate there exists a threshold of the SWNT length where the best improvement for a composite system with randomly oriented nanotubes would transition from pristine SWNTs to functionalized SWNTs.

The sampling of sulfur dioxide in air with impregnated filter paper

NARCIS (Netherlands)

Huygen, C.

1963-01-01

A method is suggested for the sampling of sulfur dioxide in air with impregnated filter paper instead of bubblers. The best aqueous impregnating solution contained potassium hydroxide with glycerol or triethanolamine. The possibilities and limitations of the method are discussed. High collection

Halloysite reinforced epoxy composites with improved mechanical properties

Directory of Open Access Journals (Sweden)

Saif Muhammad Jawwad

2016-03-01

Full Text Available Halloysite nanotubes (HNTs reinforced epoxy composites with improved mechanical properties were prepared. The prepared HNTs reinforced epoxy composites demonstrated improved mechanical properties especially the fracture toughness and flexural strength. The flexural modulus of nanocomposite with 6% mHNTs loading was 11.8% higher than that of neat epoxy resin. In addition, the nanocomposites showed improved dimensional stability. The prepared halloysite reinforced epoxy composites were characterized by thermal gravimetric analysis (TGA. The improved properties are attributed to the unique characteristics of HNTs, uniform dispersion of reinforcement and interfacial coupling.

Shape memory polymers from benzoxazine-modified epoxy

International Nuclear Information System (INIS)

Rimdusit, Sarawut; Lohwerathama, Montha; Dueramae, Isala; Hemvichian, Kasinee; Kasemsiri, Pornnapa

2013-01-01

Novel shape memory polymers (SMPs) were prepared from benzoxazine-modified epoxy resin. Specimens consisting of aromatic epoxy (E), aliphatic epoxy (N), Jeffamine D230 (D) and BA-a benzoxazine monomer (B) were evaluated. The mole ratio of D/B was used as a mixed curing agent for an epoxy system with a fixed E/N. The effects of BA-a content on the thermal, mechanical and shape memory properties of epoxy-based shape memory polymers (SMPs) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), flexural test and shape recovery test. The results revealed that the obtained SMPs exhibited a higher flexural strength and flexural modulus than those of the unmodified epoxy-based SMP at room temperature and at 20 ° C above glass transition temperature (T g ). The presence of 1 mol BA-a as a curing agent provided the specimen with the highest T g , i.e. about 72 ° C higher than that of epoxy-based SMP cured by Jeffamine D230. All SMP samples needed only a few minutes to fully recover to their original shape. The samples exhibited high shape fixity (98–99%) and shape recovery ratio (90–100%). In addition, the recovery stress values increased with increasing BA-a mole ratio from 20 to 38 kPa, when BA-a up to 1 mol ratio was added. All of the SMP samples exhibited only minimum change in their flexural strength at the end of a 100 recovery cycles test. (paper)

Research and development of lithium isotope separation using an ionic-liquid impregnated organic membrane

International Nuclear Information System (INIS)

Hoshino, Tsuyoshi

2013-01-01

The tritium needed as a fuel for fusion reactors is produced by the neutron capture reaction of lithium-6 ( 6 Li) in tritium breeding materials. However, natural Li contains only about 7.6 at.% 6 Li. In Japan, new lithium isotope separation technique using ionic-liquid impregnated organic membranes have been developed. The improvement in the durability of the ionic-liquid impregnated organic membrane is one of the main issues for stable, long-term operation of electrodialysis cells while maintaining good performance. Therefore, we developed highly-durable ionic-liquid impregnated organic membrane. Both ends of the ionic-liquid impregnated organic membrane were covered by a nafion 324 overcoat to prevent the outflow of the ionic liquid. The transmission of Lithium aqueous solution after 10 hours under the highly-durable ionic-liquid impregnated organic membrane is almost 13%. So this highly-durable ionic-liquid impregnated organic membrane for long operating of electrodialysis cells has been developed through successful prevention of ion liquid dissolution. (J.P.N.)

Quantifying voids effecting delamination in carbon/epoxy composites: static and fatigue fracture behavior

Science.gov (United States)

Hakim, I.; May, D.; Abo Ras, M.; Meyendorf, N.; Donaldson, S.

2016-04-01

On the present work, samples of carbon fiber/epoxy composites with different void levels were fabricated using hand layup vacuum bagging process by varying the pressure. Thermal nondestructive methods: thermal conductivity measurement, pulse thermography, pulse phase thermography and lock-in-thermography, and mechanical testing: modes I and II interlaminar fracture toughness were conducted. Comparing the parameters resulted from the thermal nondestructive testing revealed that voids lead to reductions in thermal properties in all directions of composites. The results of mode I and mode II interlaminar fracture toughness showed that voids lead to reductions in interlaminar fracture toughness. The parameters resulted from thermal nondestructive testing were correlated to the results of mode I and mode II interlaminar fracture toughness and voids were quantified.

Chromatographic assessment of two hybrid monoliths prepared via epoxy-amine ring-opening polymerization and methacrylate-based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer.

Science.gov (United States)

Wang, Hongwei; Ou, Junjie; Lin, Hui; Liu, Zhongshan; Huang, Guang; Dong, Jing; Zou, Hanfa

2014-11-07

Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65°C for 12h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60°C for 12h. Two hybrid monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA-DAD monolith possessed higher column efficiencies (25,000-34,000plates/m) for the separation of alkylbenzenes than the epoxy-MA-EDMA monolith (12,000-13,000plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine monoliths, the epoxy-MA-EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA-DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA-DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA-DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA-EDMA monolith when compared with that on pristine epoxy-MA-EDMA monolith. The enhancement of the column efficiency of epoxy-MA-DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC. Copyright © 2014 Elsevier B.V. All

The sampling of hydrogen sulfide in air with impregnated filter paper

NARCIS (Netherlands)

Huygen, C.

1964-01-01

A method is proposed for the quantitative collection of hydrogen sulfide in air on impregnated filter paper. An aqueous solution of potassium hydroxide, potassium zincate and glycerol is used as impregnating fluid. The stability of the collected sulfide and the efficiency of collection at different

The Effect of Water Repellent Surface Impregnation on Durability of Cement-Based Materials

Directory of Open Access Journals (Sweden)

Peng Zhang

2017-01-01

Full Text Available In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement or by carbonation of the covercrete. Water repellent treatment on the surfaces of cement-based materials has often been considered to protect concrete from these deteriorations. In this paper, three types of water repellent agents have been applied on the surface of concrete specimens. Penetration profiles of silicon resin in treated concrete have been determined by FT-IR spectroscopy. Water capillary suction, chloride penetration, carbonation, and reinforcement corrosion in both surface impregnated and untreated specimens have been measured. Results indicate that surface impregnation reduced the coefficient of capillary suction of concrete substantially. An efficient chloride barrier can be established by deep impregnation. Water repellent surface impregnation by silanes also can make the process of carbonation action slow. In addition, it also has been concluded that surface impregnation can provide effective corrosion protection to reinforcing steel in concrete with migrating chloride. The improvement of durability and extension of service life for reinforced concrete structures, therefore, can be expected through the applications of appropriate water repellent surface impregnation.

Influence of Reinforcement Anisotropy on the Stress Distribution in Tension and Shear of a Fusion Magnet Insulation System

Science.gov (United States)

Humer, K.; Raff, S.; Prokopec, R.; Weber, H. W.

2008-03-01

A glass fiber reinforced plastic laminate, which consists of half-overlapped wrapped Kapton/R-glass-fiber reinforcing tapes vacuum-pressure impregnated in a cyanate ester/epoxy blend, is proposed as the insulation system for the ITER Toroidal Field coils. In order to assess its mechanical performance under the actual operating conditions, cryogenic (77 K) tensile and interlaminar shear tests were done after irradiation to the ITER design fluence of 1×1022 m-2 (E>0.1 MeV). The data were then used for a Finite Element Method (FEM) stress analysis. We find that the mechanical strength and the fracture behavior as well as the stress distribution and the failure criteria are strongly influenced by the winding direction and the wrapping technique of the reinforcing tapes.

Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids

Science.gov (United States)

Yang, Cheng-Fu; Wang, Li-Fen; Wu, Song-Mao; Su, Chean-Cheng

2015-01-01

The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images. PMID:28793616

High-performance fiber/epoxy composite pressure vessels

Science.gov (United States)

Chiao, T. T.; Hamstad, M. A.; Jessop, E. S.; Toland, R. H.

1978-01-01

Activities described include: (1) determining the applicability of an ultrahigh-strength graphite fiber to composite pressure vessels; (2) defining the fatigue performance of thin-titanium-lined, high-strength graphite/epoxy pressure vessel; (3) selecting epoxy resin systems suitable for filament winding; (4) studying the fatigue life potential of Kevlar 49/epoxy pressure vessels; and (5) developing polymer liners for composite pressure vessels. Kevlar 49/epoxy and graphite fiber/epoxy pressure vessels, 10.2 cm in diameter, some with aluminum liners and some with alternation layers of rubber and polymer were fabricated. To determine liner performance, vessels were subjected to gas permeation tests, fatigue cycling, and burst tests, measuring composite performance, fatigue life, and leak rates. Both the metal and the rubber/polymer liner performed well. Proportionately larger pressure vessels (20.3 and 38 cm in diameter) were made and subjected to the same tests. In these larger vessels, line leakage problems with both liners developed the causes of the leaks were identified and some solutions to such liner problems are recommended.

Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

Energy Technology Data Exchange (ETDEWEB)

Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Quimica; Ferreira, Glaucio B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Quimica; Mota, Claudio J.A., E-mail: cmota@iq.ufrj.br [INCT Energia e Ambiente, Universidade Federal do Rio de Janeiro, RJ (Brazil)

2013-01-15

The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

International Nuclear Information System (INIS)

Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C.

2013-01-01

The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

Viscoelastic properties of graphene-based epoxy resins

Science.gov (United States)

Nobile, Maria Rossella; Fierro, Annalisa; Rosolia, Salvatore; Raimondo, Marialuigia; Lafdi, Khalid; Guadagno, Liberata

2015-12-01

In this paper the viscoelastic properties of an epoxy resin filled with graphene-based nanoparticles have been investigated in the liquid state, before curing, by means of a rotational rheometer equipped with a parallel plate geometry. Exfoliated graphite was prepared using traditional acid intercalation followed by a sudden treatment at high temperature (900°C). The percentage of exfoliated graphite was found to be 56%. The epoxy matrix was prepared by mixing a tetrafunctional precursor with a reactive diluent which produces a significant decrease in the viscosity of the epoxy precursor so that the dispersion step of nanofillers in the matrix can easily occur. The hardener agent, the 4,4-diaminodiphenyl sulfone (DDS), was added at a stoichiometric concentration with respect to all the epoxy rings. The inclusion of the partially exfoliated graphite (pEG) in the formulated epoxy mixture significantly modifies the rheological behaviour of the mixture itself. The epoxy mixture, indeed, shows a Newtonian behaviour while, at 3 wt % pEG content, the complex viscosity of the nanocomposite clearly shows a shear thinning behaviour with η* values much higher at the lower frequencies. The increase in complex viscosity with the increasing of the partially exfoliated graphite content was mostly caused by a dramatic increase in the storage modulus. All the graphene-based epoxy mixtures were cured by a two-stage curing cycles: a first isothermal stage was carried out at the lower temperature of 125°C for 1 hour while the second isothermal stage was performed at the higher temperature of 200°C for 3 hours. The mechanical properties of the cured nanocomposites show high values in the storage modulus and glass transition temperature.

Epoxy Nanocomposites Containing Zeolitic Imidazolate Framework-8.

Science.gov (United States)

Liu, Cong; Mullins, Michael; Hawkins, Spencer; Kotaki, Masaya; Sue, Hung-Jue

2018-01-10

Zeolitic imidazole framework-8 (ZIF-8) is utilized as a functional filler and a curing agent in the preparation of epoxy nanocomposites. The imidazole group on the surface of the ZIF-8 initiates epoxy curing, resulting in covalent bonding between the ZIF-8 crystals and epoxy matrix. A substantial reduction in dielectric constant and increase in tensile modulus were observed. The implication of the present study for utilization of metal-organic framework to improve physical and mechanical properties of polymeric matrixes is discussed.

Plasma Treated Multi-Walled Carbon Nanotubes (MWCNTs for Epoxy Nanocomposites

Directory of Open Access Journals (Sweden)

Jie Lian

2011-12-01

Full Text Available Plasma nanocoating of allylamine were deposited on the surfaces of multi-walled carbon nanotubes (MWCNTs to provide desirable functionalities and thus to tailor the surface characteristics of MWCNTs for improved dispersion and interfacial adhesion in epoxy matrices. Plasma nanocoated MWCNTs were characterized using scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HR-TEM, surface contact angle, and pH change measurements. Mechanical testing results showed that epoxy reinforced with 1.0 wt % plasma coated MWCNTs increased the tensile strength by 54% as compared with the pure epoxy control, while epoxy reinforced with untreated MWCNTs have lower tensile strength than the pure epoxy control. Optical and electron microscopic images show enhanced dispersion of plasma coated MWCNTs in epoxy compared to untreated MWCNTs. Plasma nanocoatings from allylamine on MWCNTs could significantly enhance their dispersion and interfacial adhesion in epoxy matrices. Simulation results based on the shear-lag model derived from micromechanics also confirmed that plasma nanocoating on MWCNTs significantly improved the epoxy/fillers interface bonding and as a result the increased composite strength.

Development of AlN/Epoxy Composites with Enhanced Thermal Conductivity

Science.gov (United States)

Xu, Yonggang; Yang, Chi; Li, Jun; Zhang, Hailong; Hu, Song; Wang, Shiwei

2017-01-01

AlN/epoxy composites with high thermal conductivity were successfully prepared by infiltrating epoxy into AlN porous ceramics which were fabricated by gelcasting of foaming method. The microstructure, mechanical, and thermal properties of the resulting composites were investigated. The compressive strengths of the AlN/epoxy composites were enhanced compared with the pure epoxy. The AlN/epoxy composites demonstrate much higher thermal conductivity, up to 19.0 W/(m·K), compared with those by the traditional particles filling method, because of continuous thermal channels formed by the walls and struts of AlN porous ceramics. This study demonstrates a potential route to manufacture epoxy-based composites with extremely high thermal conductivity. PMID:29258277

Development of AlN/Epoxy Composites with Enhanced Thermal Conductivity.

Science.gov (United States)

Xu, Yonggang; Yang, Chi; Li, Jun; Mao, Xiaojian; Zhang, Hailong; Hu, Song; Wang, Shiwei

2017-12-18

AlN/epoxy composites with high thermal conductivity were successfully prepared by infiltrating epoxy into AlN porous ceramics which were fabricated by gelcasting of foaming method. The microstructure, mechanical, and thermal properties of the resulting composites were investigated. The compressive strengths of the AlN/epoxy composites were enhanced compared with the pure epoxy. The AlN/epoxy composites demonstrate much higher thermal conductivity, up to 19.0 W/(m·K), compared with those by the traditional particles filling method, because of continuous thermal channels formed by the walls and struts of AlN porous ceramics. This study demonstrates a potential route to manufacture epoxy-based composites with extremely high thermal conductivity.

Processing of intractable polymers using reactive solvents. 2. Poly(2,6-Dimethyl-1,4-Phenylene Ether) as a Matrix Material for High-Performance Composites

NARCIS (Netherlands)

Venderbosch, R.W.; Meijer, H.E.H.; Lemstra, P.J.

1995-01-01

The application of poly(2,6-dimethyl-1,4-phenylene ether) (PPE) as a matrix material for continuous carbon fibre reinforced composites has been studied. Owing to the intractable nature of PPE, melt impregnation is not feasible and therefore a solution impregnation route was explored using epoxy

Radiation processing of carbon fiber-acrylated epoxy composites

International Nuclear Information System (INIS)

Singh, A.; Saunders, C.B.

1992-01-01

Advanced composites, specifically carbon fiber reinforced epoxies, are being used for a variety of demanding structural applications, primarily because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance, and damage tolerance characteristics. For these composites the key advantages of using electron beam (EB), rather than thermal curing, are curing at ambient temperature, reduced curing times for individual components, improved resin stability, fewer volatiles, and better control of the profile of energy absorption. Epoxy compounds do, however, have to be modified to make them EB curable. The electron beam penetration limit, a function of beam energy, product density, and the thickness of any container required, must also be examined when considering EB processing. Research is being conducted to develop EB-curable carbon fiber-acrylated epoxy composites. The tensile properties of these laminates are comparable to those of thermally cured epoxy laminates. Research is continuing to develop suitable resin formulations and coupling agents to optimize the mechanical properties of EB-cured carbon fiber laminates. In this chapter the EB curing of epoxies, processing considerations, and typical properties of EB-cured carbon fiber-acrylated epoxy laminates are discussed. (orig.)

Thermal-mechanical properties of a graphitic-nanofibers reinforced epoxy.

Science.gov (United States)

Salehi-Khojin, Amin; Jana, Soumen; Zhong, Wei-Hong

2007-03-01

We previously developed a series of reactive graphitic nanofibers (r-GNFs) reinforced epoxy (nano-epoxy) as composite matrices, which have shown good wetting and adhesion properties with continuous fiber. In this work, the thermal-mechanical properties of the nano-epoxy system containing EponTM Resin 828 and Epi-cure Curing Agent W were characterized. Results from three-point bending tests showed that the flexural strength and flexural modulus of this system with 0.30 wt% of reactive nanofibers were increased by 16%, and 21% respectively, over pure epoxy. Fracture toughness increased by ca. 40% for specimens with 0.50 wt% of r-GNFs. By dynamic mechanical analysis (DMA) test, specimens with 0.30 wt% of r-GNFs showed a significant increase in storage modulus E' (by ca. 122%) and loss modulus E" (by ca. 111%) with respect to that of pure epoxy. Also thermo-dilatometry analysis (TDA) was used to measure dimensional change of specimens as a function of temperature, and then, coefficients of thermal expansion (CTE) before and after glass transition temperature (Tg) were obtained. Results implied that nano-epoxy materials had good dimensional stability and reduced CTE values when compared to those of pure epoxy.

Processing effects in production of composite prepreg by hot melt impregnation

Science.gov (United States)

Chmielewski, C.; Jayaraman, K.; Petty, C. A.

1993-06-01

The hot melt impregnation process for producing composite prepreg has been studied. The role of the exit die is highlighted by operating without impregnation bars. Experimental results show that when a fiber tow is pulled through a resin bath and then through a wedge shaped die, the total resin mass fraction and the extent of resin impregnation in the tow increase with the processing viscosity. The penetration of resin into a fiber bundle is greater when the resin viscosity is higher. This trend is unchanged over a range of tow speeds up to the breaking point. A theoretical model is developed to describe the effect of processing conditions and die geometry on the degree of impregnation. Calculations with this model indicate that for a given die geometry, the degree of impregnation increases from 58 percent to 90 percent as the ratio of the clearance between the tow and the die wall, to the total die gap is decreased from 0.15 to 0.05. Physical arguments related to the effective viscosity of the prepreg show that the clearance ratio is independent of the tow speed, but decreases as the ratio of the effective shear viscosity of the prepreg to the resin viscosity increases. This provides a connection between the experimental results obtained with varying resin viscosity and the computational results obtained with varying clearance values at the die inlet.

Green Preparation of Epoxy/Graphene Oxide Nanocomposites Using a Glycidylamine Epoxy Resin as the Surface Modifier and Phase Transfer Agent of Graphene Oxide.

Science.gov (United States)

Tang, Xinlei; Zhou, Yang; Peng, Mao

2016-01-27

In studies of epoxy/graphene oxide (GO) nanocomposites, organic solvents are commonly used to disperse GO, and vigorous mechanical processes and complicated modification of GO are usually required, increasing the cost and hindering the development and application of epoxy nanocomposites. Here, we report a green, facile, and efficient method of preparing epoxy/GO nanocomposites. When triglycidyl para-aminophenol (TGPAP), a commercially available glycidyl amine epoxy resin with one tertiary amine group per molecule, is used as both the surface modifier and phase transfer agent of GO, GO can be directly and rapidly transferred from water to diglycidyl ether of bisphenol A and other types of epoxy resins by manual stirring under ambient conditions, whereas GO cannot be transferred to these epoxy resins in the absence of TGPAP. The interaction between TGPAP and GO and the effect of the TGPAP content on the dispersion of GO in the epoxy matrix were investigated systematically. Superior dispersion and exfoliation of GO nanosheets and remarkably improved mechanical properties, including tensile and flexural properties, toughness, storage modulus, and microhardness, of the epoxy/GO nanocomposites with a suitable amount of TGPAP were demonstrated. This method is organic-solvent-free and technically feasible for large-scale preparation of high-performance nanocomposites; it opens up new opportunities for exploiting the unique properties of graphene or even other nanofillers for a wide range of applications.

Performance of epoxy-nanocomposite under corrosive environment

Directory of Open Access Journals (Sweden)

2007-06-01

Full Text Available Nanocomposite materials consisting of polymeric matrix materials and natural or synthetic layered minerals like clay are currently an expanding field of study because these new materials often exhibit a wide range of improved properties over their unmodified starting polymers. Epoxy/organoclay nanocomposites have been prepared by intercalating epoxy into the organoclay via direct mixing process. The clay exfoliation was monitored by X-ray diffraction (XRD and transmission electron microscopy (TEM. Water diffusion and sulfuric acid corrosion resistance of epoxy-based nanocomposites were evaluated. Diffusion was studied through epoxy samples containing up to 6 phr (parts per hundred resin of an organically treated montmorillonite. The diffusion of the environmental solution was measured by noting the increase in weight of the samples as a function of immersion time in these solutions at 80°C. The effect of the degree of exfoliation of the organoclay on water barrier and corrosion resistance was specifically studied. The data have been compared to those obtained from the neat epoxy resin to evaluate the diffusion properties of the nanocomposites. The flexural strength of the epoxy/organoclay nanocomposites samples made was examined to compare their mechanical performance under corrosive conditions as a function of immersion time and temperature. It was found, that the organoclay was mainly intercalated with some exfoliation and that addition of the organoclay yields better flexural strength retention under immersion into sulfuric acid.

Estimation of tribological anticorrosion properties of impregnated nitriding layers

International Nuclear Information System (INIS)

Iwanow, J.; Senatorski, J.; Tacikowski, J.

1999-01-01

In this paper is described aim, experimental and test result of tribological anticorrosion properties of thin nitriding layer (12.5 μm) obtained on 45 steel grade in controlled gas-nitriding process (570 o C, 4 h) impregnated with oil-based formulations, containing corrosion inhibitor BS-43, modified with tribological additives based on ashen organometallic compounds as well as ash-free organic compounds. It was stated, that tribological additives does not influence, in fact, on behaviour of corrosion resistance of nitriding layers impregnated with oil-base formulations mainly connected with inhibitor BS-43. Synergy of tribological additive and corrosion inhibitor is however more visible in modelling of wear resistance of nitriding layer. The influence nature of tribological additives in combination with corrosion inhibitor BS-43 is dependent on their kind and as result improves or worsens the wear resistance by friction. Hence in choice of impregnated formulation, which is enable to accomplish of tribological anticorrosion requirements, determined, above all, tribological additive. (author)

Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

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Worawat Wattanathana

2017-01-01

Full Text Available Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO2 powders were synthesized by thermal decomposition of cerium(III complexes prepared by using cerium(III nitrate or cerium(III chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H2 in He stream at 700°C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pdδ+ (δ > 2 species than the materials prepared from cerium(III-triethanolamine complexes. Consequently, it exhibited the most efficient catalytic activity in the methane steam reforming reaction. By optimization of the metal complex precursors, characteristics of the obtained palladium-impregnated ceria catalysts can be modified and hence influence the catalytic activity.

In-situ Elevated Temperature Mechanical Performance of MWCNT/epoxy Nanocomposite

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Bhanu Pratap Singh

2017-03-01

Full Text Available The present investigation has been focused on the effects of multi-walled carbon nanotube (MWCNT addition on the mechanical performance of epoxy under different in-service elevated temperature environments. Room temperature flexural test results revealed that addition of 0.1 wt. % MWCNT into epoxy resin resulted in modulus and strength enhancement of 21 % and 9 % respectively. With increase in service temperature, significant decrement in both modulus and strength was noticed for both materials (neat epoxy and MWCNT/epoxy nanocomposite, but the rate of degradation was found to be quite drastic for the nanocomposite. At 90 °C temperature, the CNT/epoxy nanocomposite exhibited inferior modulus and strength, which are 41 % and 59 % lower than neat epoxy respectively. The variation trend in elastic modulus with temperature obtained from both flexural testing and DMA for both these materials was also analyzed. It was found that addition of 0.1 % CNT in the epoxy reduced the glass transition temperature by about 16°C.

Evaluation of the mechanical properties of carbon fiber after electron beam irradiation

International Nuclear Information System (INIS)

Giovedi, Claudia; Diva Brocardo Machado, Luci; Augusto, Marcos; Segura Pino, Eddy; Radino, Patricia

2005-01-01

Carbon fibers are used as reinforcement material in epoxy matrix in advanced composites. An important aspect of the mechanical properties of composites is associated to the adhesion between the surface of the carbon fiber and the epoxy matrix. This paper aimed to the evaluation of the effects of EB irradiation on the tensile properties of two different carbon fibers prepared as resin-impregnated specimens. The fibers were EB irradiated before the preparation of the resin-impregnated specimens for mechanical tests. Observations of the specimens after breakage have shown that EB irradiation promoted significant changes in the failure mode. Furthermore, the tensile strength data obtained for resin-impregnated specimens prepared with carbons fibers previously irradiated presented a slight tendency to be higher than those obtained from non-irradiated carbon fibers

Antimicrobial-impregnated dressing combined with negative-pressure wound therapy increases split-thickness skin graft engraftment: a simple effective technique.

Science.gov (United States)

Wu, Cheng-Chun; Chew, Khong-Yik; Chen, Chien-Chang; Kuo, Yur-Ren

2015-01-01

Immobilization and adequate surface contact to wounds are critical for skin graft take. Techniques such as the tie-over dressing, cotton bolster, and vacuum-assisted closure are used to address this, but each has its limitations. This study is designed to assess the effect of antimicrobial-impregnated dressing (AMD) combined with negative-pressure wound therapy (NPWT) on skin graft survival. Retrospective case-control study : Patients with chronic or contaminated wounds treated with split-thickness skin graft. A broad spectrum of wounds was included, from causes such as trauma, burns, chronic diabetic ulcers, and infection. Antimicrobial-impregnated dressing, which contains 0.2% polyhexamethylene biguanide, with NPWT MAIN OUTCOME MEASURE:: Success of skin graft : In the AMD group, all skin grafts achieved 100% take without secondary intervention. No infection or graft failure was observed in any patients, and no complications, such as hematoma or seroma formation, were noted, although in the control group partial loss of skin grafts was noted in 3 patients. Infection and inadequate immobilization were thought to be the main reasons. There were no hematoma or seroma formations in the control group. Use of an AMD dressing with NPWT after split-thickness skin grafting can be an effective method to ensure good graft to wound contact and enhances skin graft take in chronic and contaminated wounds.

In situ treatment of concrete surfaces by organic impregnation and polymerization

International Nuclear Information System (INIS)

Ursella, P.; Moretti, G.; Pellecchia, V.

1990-01-01

The impregnation by resins of concrete structures is a process well known at PIC (Polymer Impregnated Concrete). This process improves the physical-chemical features of concrete matrixes in order to extend their durability when severe environmental conditions may occur. The main objective of this research contract has been the verification of a proper impregnation 'in situ' of existing concrete surfaces, of any laying in the space, by means of a prototype machine, expressly designed and implemented, and verification of the increase of mechanical resistance, leach resistance, durability of treated material. In a nuclear facility this goal is very important in relation to the long term integrity of concrete structures during operating lifetime and, in particular, after final shutdown. (author)

Characteristic of Polymer-Impregnated Cement Mortar: Composites: Bulk Density and Microstructure

International Nuclear Information System (INIS)

Younes, M.M.; Abo-El-Enein, S.A.; El-Saft, M.M.; Sadek, M.A.; Zohdy, K.M.

2010-01-01

The effect of radiation initiated polymerization of some monomers on the physical properties of polymer-incorporated mortar was studied. The monomers used were: castor oil (C.O.), 4, 4'-diphenylmethane diisocyanate (MDI) and methyl methacrylate (MMA). Polymerization was carried out by subjecting the monomer-impregnated mortar specimens to different doses of gamma radiation. Where polyurethane (pu) and polyurethane -methyl methacrylate copolymers were formed within the pore system. The influence of polymer impregnation on the various physico-mechanical characteristics of the resulting composites was studied with respect to bulk density and polymer loading. Scanning electron microscopy (SEM) was employed to study the micro-structural characteristics of the neat hardened Ordinary Portland Cement (OPC) mortar pastes and their polymer-impregnated composites

Evaluation of the high-voltage high-frequency transformer insulating materials for satellites

International Nuclear Information System (INIS)

Kurita, Hiroshi; Hasegawa, Taketoshi; Hirasawa, Eiichi; Gonai, Toshio; Ohsuga, Hiroyuki.

1987-01-01

Environment resistance evaluation was made of the insulating materials of impregnated injection type for high-voltage high-frequency transformers mounted in satellites. (1) The stress occurring in the impregnated injection type resin is small in silicon resin and urethane resin and large in epoxy resin. (2) The dielectric characteristic at high frequency is good in silicone resin. In epoxy resin, when the transformer is operated at high temperature, its thermal runaway may take place. (3) The radiation deterioration at 1 Mrad - 10 Mrad is slight in urethane resin. (4) The degassing is not good in silicone resin. (5) The adhesive power is good in urethane resin. (6) From the above results, in silicone resin there is problem in degassing and adhesive power. In epoxy resin there is problem in stress and dielectric characteristic. (Mori, K.)

Optical study of planar waveguides based on oxidized porous silicon impregnated with laser dyes

Energy Technology Data Exchange (ETDEWEB)

Chouket, A. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanar 2092, Tunis (Tunisia); Charrier, J. [Laboratoire d' Optronique CNRS-UMR FOTON 6082, Universite de Rennes 1, ENSSAT-6 rue de Kerampont, BP 80518, 22305 Lannion Cedex (France); Elhouichet, H. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanar 2092, Tunis (Tunisia)], E-mail: habib.elhouichet@fst.rnu.tn; Oueslati, M. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanar 2092, Tunis (Tunisia)

2009-05-15

Oxidized porous silicon optical planar waveguides were elaborated and impregnated with rhodamine B and rhodamine 6G. The waveguiding, absorption, and photoluminescence properties of these impregnated waveguides were studied. Successful impregnation of the structure with laser dyes is shown from photoluminescence and reflectivity measurements. Furthermore, the reflectivity spectra prove the homogenous incorporation of both dye molecules inside the pores of the matrices. The refractive indices of waveguide layers were determined before and after dye impregnation to indicate the conservation of guiding conditions. The optical losses in the visible wavelengths are studied as a function of dye concentration. The dye absorption is the main reason for these losses.

Impregnation of mesoporous silica for catalyst preparation studied with differential scanning calorimetry

NARCIS (Netherlands)

Eggenhuisen, T.M.; van Steenbergen, M.J.; Talsma, H.; de Jongh, P.E.; de Jong, K.P.

2009-01-01

Aqueous impregnation of mesoporous silica as a first step in catalyst preparation was studied to investigate the distribution of the metal-precursor solution over the support. The degree of pore-filling after impregnation was determined using the freezing point depression of confined liquids. A

Prediction of brittle fracture of epoxy-aluminum flanging

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Korbel J.

2010-07-01

Full Text Available This paper presents a fracture mechanical approach for estimation of critical bending load of different types of aluminum-epoxy flanging and comparison with experimental measurements. For this purpose, several designs of the flanges were investigated. The flanges were glued to the epoxy bars and adhesive-epoxy interface was considered as a bi-material notch. Prediction of the failure is based on generalized stress intensity factor and generalized fracture toughness.

Accelerated thermal aging of rubber modified epoxy encapsulants

International Nuclear Information System (INIS)

Sayre, J.A.

1979-01-01

A program is outlined to enable prediction of physical properties of rubber modified epoxy encapsulants over the life time of the extended life neutron generators. Preliminary results show that the chief aging phenomenon occurring is increased crosslink density of the epoxy matrix. No changes in the rubber phase have been detected. The effect of increased epoxy crosslink density has been higher volume resistivity at 66 0 C, increased tensile strength, and decreased ultimate elongation

Different Types of Waste Melamine Impregnated Paper (MIP in Particleboard Manufacturing

Directory of Open Access Journals (Sweden)

Ibrahim Halil BASBOGA

2017-03-01

Full Text Available Two different types of waste melamine impregnated paper (WMIP were generated in the manufactured coated board product plants. First one is obtained when the neat décor papers were impregnated (in the impregnation line with melamine urea formaldehyde and other chemicals (WMIP1. The second one is generated during the coating of the melamine impregnated papers on the board surfaces (WMIP2. In this study, the utilization of both WMIPs in the production of particleboard as an adhesivereplacement was investigated. First, waste melamine impregnated papers (WMIPs granulated into flour form using Pulverizator with cooling capabilities. Then, they were dry-mixed with surface and core layer particles at 10% or 15% loadings. Three different WMIPs (WMIP1, WMIP2 or their mixtures - 70% WMIP1+30% WMIP2 were used as adhesive-replacement. Mechanical properties including bending strength, modulus of elasticity, internal bond strength and surface stability of the samples were determined according to EN 310, EN 319 and EN 317 standards, respectively. Based on the results, the type of WMIP had significant effect on all mechanical properties investigated. Particleboards produced with both 10% and 15% of WMIP1 loading provided adequate results for the related standards. The best result was obtained when 15% of WMIP1 was used. It is concluded that WMIP1 might be used as an adhesive-replacement in particleboard manufacturing and may provide economic and environmental benefits.

Thermoset epoxy polymers from renewable resources

Science.gov (United States)

East, Anthony [Madison, NJ; Jaffe, Michael [Maplewood, NJ; Zhang, Yi [Harrison, NJ; Catalani, Luiz H [Carapicuiba, BR

2009-11-17

Novel thermoset epoxy polymers using the bisglycidyl ethers of anhydrosugars, such as isosorbide, isomannide, and isoidide, are disclosed. The bisglycidyl ethers are useful as substitutes for bisphenol A in the manufacture of thermoset epoxy ethers. The anhydrosugars are derived from renewable sources and the bisglycidyl ethers are not xenoestrogenic and the thermoset curing agents are likewise derived form renewable resources.

Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites

International Nuclear Information System (INIS)

Sarathi, R.; Sahu, R.K.; Rajeshkumar, P.

2007-01-01

In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results

Modeling and mechanical performance of carbon nanotube/epoxy resin composites

International Nuclear Information System (INIS)

Srivastava, Vijay Kumar

2012-01-01

Highlights: ► The MWCNT fillers are uniformly dispersed in the epoxy resin, which improved the mechanical properties of epoxy resin. ► Modified Halpin–Tsai model is useful to calculate the Young’s modulus of MWCNT/epoxy resin composite. ► The experimental moduli are within the variation of 27% with the theoretical values. -- Abstract: The effect of multi-walled carbon nanotube (MWCNT) addition on mechanical properties of epoxy resin was investigated to obtain the tensile strength, compressive strength and Young’s modulus from load versus displacement graphs. The result shows that the tensile strength, compressive strength and Young’s modulus of epoxy resin were increased with the addition of MWCNT fillers. The significant improvements in tensile strength, compressive strength and Young’s modulus were obtained due to the excellent dispersion of MWCNT fillers in the epoxy resin. The dispersion of MWCNT fillers in epoxy resin was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Also, Halpin–Tsai model was modified by considering the average diameter of internal/external of multi-walled nanotube and orientation factor (α) to calculate the Young’s modulus of multi-walled carbon nanotubes (MWCNTs)/epoxy resin composite. There was a good correlation between the experimentally obtained Young’s modulus and modified Halpin–Tsai model.

The failure mode of natural silk epoxy triggered composite tubes

International Nuclear Information System (INIS)

Eshkour, R A; Ariffin, A K; Zulkifli, R; Sulong, A B; Azhari, C H

2012-01-01

In this study the quasi static compression test over natural silk epoxy triggered composite tubes has been carried out, the natural silk epoxy composite tubes consist of 24 layer of woven natural silk as reinforcement and thermoset epoxy resin as matrix which both of them i e natural silk and epoxy have excellent mechanical properties More over the natural silk have better moisture resistance in comparison with other natural reinforcements, the length of tubes are 50, 80 and 120 mm The natural silk epoxy composite tubes are associated with an external trigger which includes 4 steel pieces welded on downside flat plate fixture The hand lay up fabrication method has been used to make the natural silk epoxy composite tubes Instron universal testing machine with 250 KN load capacity has been employed to accomplish this investigation The failure modes of natural silk epoxy triggered composite tubes has been investigated by representative photographs which has been taken by a high resolution camera(12 2 Mp) during the quasi static compression test, from the photographs is observed the failure modes is progressive local buckling

Fracture behaviour of a self-healing microcapsule-loaded epoxy system

Directory of Open Access Journals (Sweden)

2011-03-01

Full Text Available The effect of temperature on the fracture behaviour of a microcapsule-loaded epoxy matrix was investigated. Microencapsulated epoxy and mercaptan-derivative healing agents were incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. Maximum fracture loads were measured using the double-torsion method. Thermal aging at 55 and 110°C for 17 hours [hrs] was applied to heal the pre-cracked samples. The addition of microcapsules appeared to increase significantly the load carrying capacity of the epoxy after healing. Once healed, the composites achieved as much as 93–171% of its virgin maximum fracture load at 18, 55 and 110°C. The fracture behavior of the microcapsule- loaded epoxy matrix was influenced by the healing temperature. The high self-healing efficiency may be attributed to the result of the subsurface micro-crack pinning or deviation, and to a stronger microencapsulated epoxy and mercaptanderivative binder than that of the bulk epoxy. The results show that the healing temperature has a significant effect on recovery of load transferring capability after fracture.

Epoxy/α-alumina nanocomposite with high electrical insulation performance

Directory of Open Access Journals (Sweden)

Yun Chen

2017-10-01

Full Text Available An experimental study was conducted to improve the electrical insulation of epoxy resin. The effects of boehmite, γ-alumina and α-alumina nanoparticles on the volume resistivity, dielectric strength and glass transition temperature of epoxy nanocomposites were investigated. The results showed that α-alumina nanoparticles displayed obvious advantages in enhancing electrical insulation performance of epoxy nanocomposites, compared to boehmite and γ-alumina nanoparticles. The direct current volume resistivity and breakdown strength of epoxy nanocomposite with 2.0 wt% α-alumina nanoparticles was improved to 2.2 × 1018 Ω cm and 76.1 kV mm−1 respectively. And these improved values of electrical insulation properties are much higher than these of epoxy nanocomposites reported in previous studies. The main reason of these improvements may be that the epoxy/α-alumina interaction zone was enhanced by crosslink. Keywords: Nanocomposite, Epoxy resin, Insulation, α-alumina

Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

Science.gov (United States)

Miller, Sandi G (Inventor)

2013-01-01

A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

Positron lifetime study of electron-irradiated epoxy resins

International Nuclear Information System (INIS)

Suevegh, K.; Vertes, A.; Wojnarovits, L.; Foeldiak, G.; Liszkai, L.; Kajcsos, Zs.

1990-01-01

Two bisphenol-A type epoxy resins were irradiated by electron beam and studied afterwards by positron lifetime spectroscopy. An interesting result is that despite of the considerable amount of free-radicals, no inhibition of positronium formation was observed in the two epoxies. Nevertheless, several serious differences were detected between the studied polymers. The results suggest that the radiation-resistant properties of epoxies depend strongly on the amount of the curing agent. (author) 8 refs.; 2 figs

Experimental design applied optimization of a state in epoxy clay dispersion; Planejamento de experimentos aplicado a otimizacao do estado de dispersao de argilas em epoxi

Energy Technology Data Exchange (ETDEWEB)

Paz, Juliana D' Avila; Bertholdi, Jonas; Folgueras, Marilena Valadares; Pezin, Sergio Henrique; Coelho, Luiz Antonio Ferreira, E-mail: julianadpaz@yahoo.com.b [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

2010-07-01

This paper presents some analysis showed that the exfoliation / intercalation of a montmorillonite clay in epoxy resin such as viscosity, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG). Increasing the viscosity of epoxy resin diglycidyl ether bisphenol A with the addition of clay associated with the sonification system at the time of dispersion is a good indication of exfoliation. The X-ray diffraction already cured composite shows a decrease of crystallinity of clay and EDS microanalysis of SEM, non-uniform dispersion of clay in epoxy resin. Thermal analysis TG composite clay / epoxy shows an increase in thermal stability relative to pure epoxy. (author)

Bio-Based Aromatic Epoxy Monomers for Thermoset Materials

Directory of Open Access Journals (Sweden)

Feifei Ng

2017-01-01

Full Text Available The synthesis of polymers from renewable resources is a burning issue that is actively investigated. Polyepoxide networks constitute a major class of thermosetting polymers and are extensively used as coatings, electronic materials, adhesives. Owing to their outstanding mechanical and electrical properties, chemical resistance, adhesion, and minimal shrinkage after curing, they are used in structural applications as well. Most of these thermosets are industrially manufactured from bisphenol A (BPA, a substance that was initially synthesized as a chemical estrogen. The awareness on BPA toxicity combined with the limited availability and volatile cost of fossil resources and the non-recyclability of thermosets implies necessary changes in the field of epoxy networks. Thus, substitution of BPA has witnessed an increasing number of studies both from the academic and industrial sides. This review proposes to give an overview of the reported aromatic multifunctional epoxide building blocks synthesized from biomass or from molecules that could be obtained from transformed biomass. After a reminder of the main glycidylation routes and mechanisms and the recent knowledge on BPA toxicity and legal issues, this review will provide a brief description of the main natural sources of aromatic molecules. The different epoxy prepolymers will then be organized from simple, mono-aromatic di-epoxy, to mono-aromatic poly-epoxy, to di-aromatic di-epoxy compounds, and finally to derivatives possessing numerous aromatic rings and epoxy groups.

Thermal conductivity and Kapitza resistance of cyanate ester epoxy mix and tri-functional epoxy electrical insulations at superfluid helium temperature

CERN Document Server

Pietrowicz, S; Jones, S; Canfer, S; Baudouy, B

2012-01-01

In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb$_{3}$Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 μm to 598 μm have been tested in steady-state condition in the temperature range of 1.6 K - 2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k=[(34.2±5.5).T-(16.4±8.2)]×10-3 Wm-1K-1 and for the cyanate ester epoxy k=[(26.8±4.8).T- (9...

Preparation and Properties of Moisture-absorbing Film Impregnated with Polyacrylic Acid Partial Sodium Salt Material

International Nuclear Information System (INIS)

Lee, Youn Suk; Park, Insik; Choi, Hong Yeol

2014-01-01

Moisture is a major factor causing the deteriorative physical change, microbial growth, and chemical reaction of the products. In this study, the moisture absorbing composite films have been prepared with moisture absorbing material of polyacrylic acid partial sodium salt (PAPSS) impregnated on LLDPE polymer for the functional packaging applications. The results showed that PAPSS impregnated film illustrated uniformly dispersed PAPSS particles in the LLDPE polymer matrix. The transparency of the PAPSS impregnated film decreased slightly at higher PAPSS concentrations. An increase in the PAPSS content for moisture-absorbing films showed a similar decrease in tensile strength, percent elongation at break, and tear strength. Their values of films impregnated with PAPSS of 0.5, 1, and 2% showed no significant difference. Meanwhile, 4% PAPSS films significantly decreased the values of mechanical properties compared to the films impregnated with different PAPSS levels. Values of the oxygen permeability and water vapor permeability for PAPSS impregnated films decreased significantly with greater PAPSS. The results indicate that 4% PAPSS impregnated in LLDPE films had high affinity of moisture absorbencies compared to the other films. The mathematical equation that best described the moisture sorption isotherm of each film sample was the GAB equation at 25 .deg. C. The crystallization and melting temperatures of PAPSS films were influenced by the addition of PAPSS material, but showed good thermal stability

Preparation and Properties of Moisture-absorbing Film Impregnated with Polyacrylic Acid Partial Sodium Salt Material

Energy Technology Data Exchange (ETDEWEB)

Lee, Youn Suk; Park, Insik [Yonsei University, Wonju (Korea, Republic of); Choi, Hong Yeol [CJ Cheiljedang, Seoul (Korea, Republic of)

2014-08-15

Moisture is a major factor causing the deteriorative physical change, microbial growth, and chemical reaction of the products. In this study, the moisture absorbing composite films have been prepared with moisture absorbing material of polyacrylic acid partial sodium salt (PAPSS) impregnated on LLDPE polymer for the functional packaging applications. The results showed that PAPSS impregnated film illustrated uniformly dispersed PAPSS particles in the LLDPE polymer matrix. The transparency of the PAPSS impregnated film decreased slightly at higher PAPSS concentrations. An increase in the PAPSS content for moisture-absorbing films showed a similar decrease in tensile strength, percent elongation at break, and tear strength. Their values of films impregnated with PAPSS of 0.5, 1, and 2% showed no significant difference. Meanwhile, 4% PAPSS films significantly decreased the values of mechanical properties compared to the films impregnated with different PAPSS levels. Values of the oxygen permeability and water vapor permeability for PAPSS impregnated films decreased significantly with greater PAPSS. The results indicate that 4% PAPSS impregnated in LLDPE films had high affinity of moisture absorbencies compared to the other films. The mathematical equation that best described the moisture sorption isotherm of each film sample was the GAB equation at 25 .deg. C. The crystallization and melting temperatures of PAPSS films were influenced by the addition of PAPSS material, but showed good thermal stability.

Magnetism in graphene oxide induced by epoxy groups

Energy Technology Data Exchange (ETDEWEB)

Lee, Dongwook, E-mail: dongwookleedl324@gmail.com [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Division of Physics and Applied Physics, Nanyang Technological University, Singapore 637371 (Singapore); Seo, Jiwon, E-mail: jiwonseo@yonsei.ac.kr [Department of Physics and IPAP, Yonsei University, Seoul 120-749 (Korea, Republic of); School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Zhu, Xi; Su, Haibin [Division of Materials Science, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Cole, Jacqueline M. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Argonne National Laboratory, 9700S Cass Avenue, Argonne, Illinois 60439 (United States)

2015-04-27

We have engineered magnetism in graphene oxide. Our approach transforms graphene into a magnetic insulator while maintaining graphene's structure. Fourier transform infrared spectroscopy spectra reveal that graphene oxide has various chemical groups (including epoxy, ketone, hydroxyl, and C-O groups) on its surface. Destroying the epoxy group with heat treatment or chemical treatment diminishes magnetism in the material. Local density approximation calculation results well reproduce the magnetic moments obtained from experiments, and these results indicate that the unpaired spin induced by the presence of epoxy groups is the origin of the magnetism. The calculation results also explain the magnetic properties, which are generated by the interaction between separated magnetic regions and domains. Our results demonstrate tunable magnetism in graphene oxide based on controlling the epoxy group with heat or chemical treatment.

The characteristics of epoxy resin cured by {gamma}-ray and E-beam

Energy Technology Data Exchange (ETDEWEB)

Nho, Y.C. E-mail: ycnho@kaeri.re.kr; Kang, Phil Hyun; Park, Jong Seok

2004-10-01

Epoxy resins are widely used as high-performance thermosetting resins for many industrial applications. In this study, the effect of an electron beam (E-beam) and {gamma}-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol-A(DGEBA), diglycidyl ether of bisphenol-F(DGEBF) as epoxy resins, triarylsulfonium hexafluoroantimonate(TASHFA), and triarylsulfonium hexafluorophosphate(TASHFP) as initiators were used in this study. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of E-beam and {gamma}-ray irradiation up to 50 kGy in N{sub 2} and air atmosphere. We ascertained the effect of oxygen on the radiation curing of epoxy resin. The thermal properties of cured epoxy were investigated using DMA and TGA. Mechanical properties such as flexural strength were measured. The chemical structures of cured epoxy were characterized by FT-NIR. The gel fraction and the stress at yield of epoxy resins irradiated by E-beam and {gamma}-ray in N{sub 2} atmosphere were also compared with those of epoxy resins irradiated by E-beam and {gamma}-ray in air.

Corrosion Protection of Steel by Epoxy-Organoclay Nanocomposite Coatings

OpenAIRE

Domna Merachtsaki; Panagiotis Xidas; Panagiotis Giannakoudakis; Konstantinos Triantafyllidis; Panagiotis Spathis

2017-01-01

The purpose of the present work was to study the corrosion behavior of steel coated with epoxy-(organo) clay nanocomposite films. The investigation was carried out using salt spray exposures, optical and scanning electron microscopy examination, open circuit potential, and electrochemical impedance measurements. The mechanical, thermomechanical, and barrier properties of pristine glassy epoxy polymer and epoxy-clay nanocomposites were examined. The degree of intercalation/exfoliation of clay ...

Mechanism of adhesion of epoxy resin to steel surface; Tekko hyomen to epoxy jushino secchaku mechanism

Energy Technology Data Exchange (ETDEWEB)

Nakazawa, M. [Nippon Steel Corp., Tokyo (Japan)

1994-08-01

In the present research, an adhesion-breaking test and a molecular-scale model experiment were conducted to elucidate the adhesion mechanism of epoxy resin (R) to the cold rolled steel sheet (CR) and galvanized steel sheet (GI). As for the adhesive joint strength in the humid environment, the GI is inferior in residual strength to the CR. The GI joint fracture is an interfacial fracture between the plating and adhesive agent, while the CR joint fracture is a combination of cohesive fracture and interfacial fracture. It is attributable to the difference in adhesion mechanism of R and degradation due to humidity between the surface solely of zinc and iron-containing surface. The adhesion state of R to the zinc oxide and iron oxide was observed by temperature-programed desorption in an ultrahigh vacuum. On each of both oxides, the R chemically adsorbs through bond scission between the phenoxy oxide and carbon. If the water dissociatively adsorbs onto the surface, the bond is destroyed between the zinc oxide and R. The formation of interfacial chemical bond contributes to the adhesion of R to the CR and GI. In case of GI, this band is destroyed by the interfacial infiltration of water, while it is not done in case of CR. The CR excels the GI in adhesive durability. 20 refs., 8 figs., 3 tabs.

Solvent impregnated resin for isolation of U(VI) from industrial wastes

International Nuclear Information System (INIS)

Karve, M.; Rajgor, R.V.

2008-01-01

A solid-phase extraction method based upon impregnation of Cyanex 302 (bis(2,4,4- trimethylpentyl)mono-thio-phosphinic acid) on Amberlite XAD-2 resin is proposed for isolation of U(VI) from uranmicrolite ore tailing samples and industrial effluent samples. U(VI) was sorbed from nitric acid media on the solvent-impregnated resin (SIR) and was recovered completely with 1.0 M HCl. Based upon sorption behavior of U(VI) with Cyanex 302, it was quantitatively sorbed on the SIR in a dynamic method, while the other metal ions were not sorbed by the modified resin. The preparation of impregnated resin is simple, based upon physical interaction of the extractant and solid support, has good sorption capacity for U(VI), and is also reliable for detection of traces of U(VI). (authors)

Processing, properties and applications of composites using powder-coated epoxy towpreg technology

Science.gov (United States)

Bayha, T. D.; Osborne, P. P.; Thrasher, T. P.; Hartness, J. T.; Johnston, N. J.; Marchello, J. M.; Hugh, M. K.

1993-01-01

Composite manufacturing using the current prepregging technology of impregnating liquid resin into three-dimensionally reinforced textile preforms can be a costly and difficult operation. Alternatively, using polymer in the solid form, grinding it into a powder, and then depositing it onto a carbon fiber tow prior to making a textile preform is a viable method for the production of complex textile shapes. The powder-coated towpreg yarn is stable, needs no refrigeration, contains no solvents and is easy to process into various woven and braided preforms for later consolidation into composite structures. NASA's Advanced Composites Technology (ACT) program has provided an avenue for developing the technology by which advanced resins and their powder-coated preforms may be used in aircraft structures. Two-dimensional braiding and weaving studies using powder-coated towpreg have been conducted to determine the effect of resin content, towpreg size and twist on textile composite properties. Studies have been made to customize the towpreg to reduce friction and bulk factor. Processing parameters have been determined for three epoxy resin systems on eight-harness satin fabric, and on more advanced 3-D preform architectures for the downselected resin system. Processing effects and the resultant mechanical properties of these textile composites will be presented and compared.

Thermal Effect on the phosphoric Acid Impregnated Activated Carbon Fiber and Adsorption Properties Toward Isoprene

Energy Technology Data Exchange (ETDEWEB)

Hwang, Taek Sung; Lee, Jin Hyok; Kang, Kyung suk [Department of Chemical Engineering, College of Engineering, Chungnam National University, Taejon (Korea); Kim, Kwang Young [Ace Lab. Co. Ltd. Taejon (Korea); Rhee, Moon Soo [Korea Ginseng and Tobacoo Research Institute, Taejon (Korea)

2001-05-01

To introduce chemisorption property and improve adsorption capacities for isoprene, ACF (Activated Carbon Fiber) was impregnated by phosphoric acid. As the impregnated ACF was dried by programmed temperature from 300 degree C to 500 degree C, degree of impregnation, surface area, thermal stability and adsorption properties for isoprene were observed. The degree of impregnation of the ACF, dried at the 400 degree C, was 12.7 w/w% and surface area was 1148 m{sup 2}/g. Over the temperature range of 450 degree C to 700 degree C, there was one-step thermal degradation by the thermal decomposition of phosphonyl group. The adsorption rate of phosphoric acid on the impregnated ACF, which was dried at 400 degree C, was the fastest. The breakthrough time of ACF that was dried at 400 degree C was 18 min., and its adsorption capacity improved roughly 7.2 times in comparison to the pure ACF. In addition, it was observed the adsorption properties persisted even after the regeneration. The adsorption efficiency of regenerated ACF was 66 percent compared to the unused impregnated ACF. 21 refs., 7 figs., 3 tabs.

Effects of Nanofillers on the Thermo-Mechanical Properties and Chemical Resistivity of Epoxy Nanocomposites.

Science.gov (United States)

Atchudan, Raji; Pandurangan, Arumugam; Joo, Jin

2015-06-01

MWCNTs was synthesized using Ni-Cr/MgO by CVD method and were purified. The purified MWCNT was used as a filler material for the fabrication of epoxy nanocomposites. The epoxy nanocomposites with different amount (wt% = 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0) of nanofillers (CB, SiO2 and MWCNTs) were prepared by casting method. The effects of nanofillers on the properties of neat epoxy matrix were well studied. The thermal properties of nanocomposites were studied using DSC, TGA and flame retardant, and also the mechanical properties such as tensile strength, flexural strength, compressive strength, impact strength, determination of hardness and chemical resistance were studied extensively. Based on the experiment's results, 2 wt% MWCNTs loading in epoxy resin showed the highest improvement in tensile strength, as compared to neat epoxy and to other epoxy systems (CB/epoxy, SiO2/epoxy). Improvements in tensile strength, glass transition temperature and decomposition temperature were observed by the addition of MWCNTs. The mechanical properties of the epoxy nanocomposites were improved due to the interfacial bonding between the MWCNTs and epoxy resin. Strain hardening behavior was higher for MWCNT/epoxy nanocomposites compared with CB/epoxy and SiO2/epoxy nanocomposites. The investigation of thermal and mechanical properties reveals that the incorporation of MWCNTs into the epoxy nanocomposites increases its thermal stability to a great extent. Discrete increase of glass transition temperature of nanocomposites is linearly dependent on MWCNTs content. Due to strong interfacial bonding between MWCNTs and epoxy resin, the chemical resistivity of MWCNT/epoxy nanocomposites is superior to neat epoxy and other epoxy systems.

Silane coupling agent for attaching fusion-bonded epoxy to steel.

Science.gov (United States)

Tchoquessi Diodjo, Madeleine R; Belec, Lénaïk; Aragon, Emmanuel; Joliff, Yoann; Lanarde, Lise; Perrin, François-Xavier

2013-07-24

We describe the possibility of using γ-aminopropyltriethoxysilane (γ-APS) to increase the durability of epoxy powder coating/steel joints. The curing temperature of epoxy powder coatings is frequently above 200 °C, which is seen so far as a major limitation for the use of the heat-sensitive aminosilane coupling agent. Despite this limitation, we demonstrate that aminosilane is a competitive alternative to traditional chromate conversion to enhance the durability of epoxy powder coatings/steel joints. Fourier-transform reflection-absorption infrared spectroscopy (FT-RAIRS), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were used to identify the silane deposition conditions that influence the adhesion of epoxy powder coatings on steel. We show that AFM analysis provides highly sensitive measurements of mechanical property development and, as such, the degree of condensation of the silane. The joint durability in water at 60 °C was lower when the pH of the γ-APS solution was controlled at 4.6 using formic acid, rather than that at natural pH (10.6). At the curing temperature of 220 °C, oxidation of the carbon adjacent to the amine headgroup of γ-APS gives amide species by a pseudofirst-order kinetics. However, a few amino functionalities remain to react with oxirane groups of epoxy resin and, thus, strengthen the epoxy/silane interphase. The formation of ammonium formate in the acidic silane inhibits the reaction between silane and epoxy, which consequently decreases the epoxy/silane interphase cohesion. We find that the nanoroughness of silane deposits increases with the cure temperature which is beneficial to the wet stability of the epoxy/steel joints, due to increased mechanical interlocking.

Impacts of impregnation with boric acid and borax on the red colour ...

African Journals Online (AJOL)

Impacts of impregnation with boric acid and borax on the red colour tone of some hardwoods and varnishes. H Keskin, M Atar, A Ketizmen. Abstract. This study was performed to determine the impacts of impregnation with boric acid and borax on the red colour tone of some hardwoods and varnishes. For this purpose, the ...

Comparisons of NDT Methods to Inspect Cork and Cork filled Epoxy Bands

Science.gov (United States)

Lingbloom, Mike

2007-01-01

Sheet cork and cork filled epoxy provide external insulation for the Reusable Solid Rocket Motor (RSRM) on the Nation's Space Transportation System (STS). Interest in the reliability of the external insulation bonds has increased since the Columbia incident. A non-destructive test (NDT) method that will provide the best inspection for these bonds has been under evaluation. Electronic Shearography has been selected as the primary NDT method for inspection of these bond lines in the RSRM production flow. ATK Launch Systems Group has purchased an electronic shearography system that includes a vacuum chamber that is used for evaluation of test parts and custom vacuum windows for inspection of full-scale motors. Although the electronic shearography technology has been selected as the primary method for inspection of the external bonds, other technologies that exist continue to be investigated. The NASA/Marshall Space Flight Center (MSFC) NDT department has inspected several samples for comparison with electronic shearography with various inspections systems in their laboratory. The systems that were evaluated are X-ray backscatter, terahertz imaging, and microwave imaging. The samples tested have some programmed flaws as well as some flaws that occurred naturally during the sample making process. These samples provide sufficient flaw variation for the evaluation of the different inspection systems. This paper will describe and compare the basic functionality, test method and test results including dissection for each inspection technology.

Improving molten fluoride salt and Xe135 barrier property of nuclear graphite by phenolic resin impregnation process

Science.gov (United States)

He, Zhao; Lian, Pengfei; Song, Yan; Liu, Zhanjun; Song, Jinliang; Zhang, Junpeng; Feng, Jing; Yan, Xi; Guo, Quangui

2018-02-01

A densification process has been conducted on isostatic graphite (IG-110, TOYO TANSO CO., Ltd., Japan) by impregnating phenolic resin to get the densified isostatic graphite (D-IG-110) with pore diameter of nearly 11 nm specifically for molten salt reactor application. The microstructure, mechanical, thermophysical and other properties of graphite were systematically investigated and compared before and after the densification process. The molten fluoride salt and Xe135 penetration in the graphite were evaluated in a high-pressure reactor and a vacuum device, respectively. Results indicated that D-IG-110 exhibited improved properties including infiltration resistance to molten fluoride salt and Xe135 as compared to IG-110 due to its low porosity of 2.8%, the average pore diameter of 11 nm and even smaller open pores on the surface of the graphite. The fluoride salt infiltration amount of IG-110 was 13.5 wt% under 1.5 atm and tended to be saturated under 3 atm with the fluoride salt occupation of 14.8 wt%. As to the D-IG-110, no salts could be detected even up to 10 atm attempted loading. The helium diffusion coefficient of D-IG-110 was 6.92 × 10-8 cm2/s, significantly less than 1.21 × 10-2 cm2/s of IG-110. If these as-produced properties for impregnated D-IG-110 could be retained during MSR operation, the material could prove effective at inhibiting molten fluoride salt and Xe135 inventories in the graphite.

Epoxy Nanocomposites filled with Carbon Nanoparticles.

Science.gov (United States)

Martin-Gallego, M; Yuste-Sanchez, V; Sanchez-Hidalgo, R; Verdejo, R; Lopez-Manchado, M A

2018-01-10

Over the past decades, the development of high performance lightweight polymer nanocomposites and, in particular, of epoxy nanocomposites has become one the greatest challenges in material science. The ultimate goal of epoxy nanocomposites is to extrapolate the exceptional intrinsic properties of the nanoparticles to the bulk matrix. However, in spite of the efforts, this objective is still to be attained at commercially attractive scales. Key aspects to achieve this are ultimately the full understanding of network structure, the dispersion degree of the nanoparticles, the interfacial adhesion at the phase boundaries and the control of the localization and orientation of the nanoparticles in the epoxy system. In this Personal Account, we critically discuss the state of the art and evaluate the strategies to overcome these barriers. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bacterial adhesion forces to Ag-impregnated contact lens cases and transmission to contact lenses.

Science.gov (United States)

Qu, Wenwen; Busscher, Henk J; van der Mei, Henny C; Hooymans, Johanna M M

2013-03-01

To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Adhesion forces of bacterial strains to Ag-impregnated and polypropylene lens cases and a rigid CL were measured using atomic force microscopy. Adhesion forces were used to calculate Weibull distributions, from which transmission probabilities from lens case to CL were derived. Transmission probabilities were compared with actual transmission of viable bacteria from a lens case to the CL in 0.9% NaCl and in an antimicrobial lens care solution. Bacterial transmission probabilities from polypropylene lens cases based on force analysis coincided well for all strains with actual transmission in 0.9% NaCl. Bacterial adhesion forces on Ag-impregnated lens cases were much smaller than that on polypropylene and CLs, yielding a high probability of transmission. Comparison with actual bacterial transmission indicated bacterial killing due to Ag ions during colony-forming unit transmission from an Ag-impregnated lens case, especially for P. aeruginosa. Transmission of viable bacteria from Ag-impregnated lens cases could be further decreased by use of an antimicrobial lens care solution instead of 0.9% NaCl. Bacterial transmission probabilities are higher from Ag-impregnated lens cases than from polypropylene lens cases because of small adhesion forces, but this is compensated for by enhanced bacterial killing due to Ag impregnation, especially when in combination with an antimicrobial lens care solution. This calls for a balanced combination of antimicrobial lens care solutions and surface properties of a lens case and CL.

Mechanical Reinforcement of Epoxy Composites with Carbon Fibers and HDPE

Science.gov (United States)

He, R.; Chang, Q.; Huang, X.; Li, J.

2018-01-01

Silanized carbon fibers (CFs) and a high-density polyethylene with amino terminal groups (HDPE) were introduced into epoxy resins to fabricate high-performance composites. A. mechanical characterization of the composites was performed to investigate the effect of CFs in cured epoxy/HDPE systems. The composites revealed a noticeable improvement in the tensile strength, elongation at break, flexural strength, and impact strength in comparison with those of neat epoxy and cured epoxy/HDPE systems. SEM micrographs showed that the toughening effect could be explained by yield deformations, phase separation, and microcracking.

Functionalizing CNTs for Making Epoxy/CNT Composites

Science.gov (United States)

Chen, Jian; Rajagopal, Ramasubramaniam

2009-01-01

Functionalization of carbon nanotubes (CNTs) with linear molecular side chains of polyphenylene ether (PPE) has been shown to be effective in solubilizing the CNTs in the solvent components of solutions that are cast to make epoxy/CNT composite films. (In the absence of solubilization, the CNTs tend to clump together instead of becoming dispersed in solution as needed to impart, to the films, the desired CNT properties of electrical conductivity and mechanical strength.) Because the PPE functionalizes the CNTs in a noncovalent manner, the functionalization does not damage the CNTs. The functionalization can also be exploited to improve the interactions between CNTs and epoxy matrices to enhance the properties of the resulting composite films. In addition to the CNTs, solvent, epoxy resin, epoxy hardener, and PPE, a properly formulated solution also includes a small amount of polycarbonate, which serves to fill voids that, if allowed to remain, would degrade the performance of the film. To form the film, the solution is drop-cast or spin-cast, then the solvent is allowed to evaporate.

Study of adsorption properties of impregnated charcoal for airborne iodine and methyl iodide

International Nuclear Information System (INIS)

Qi-dong, L.; Sui-yuang, H.

1985-01-01

The adsorption characteristics of airborne radioiodine and methyl iodide on impregnated charcoal were investigated. The activated charcoal tested was made from home-made oil-palm shells, and KI and TEDA were used as impregnants. A new technique was used to plot the dynamic partial adsorption isotherm at challenge concentrations (concentration range of iodine: 1-20 ppm v/v). Some adsorption properties of the impregnated charcoal were estimated with the dynamic partial adsorption isotherm. The dependences of the adsorption capacity and penetration behavior for airborne iodine and methyl iodide on the ambient conditions (temperature, relative humidity, and superficial velocity) were studied

Preparation and Performance of Amphiphilic Random Copolymer Noncovalently Modified MWCNTs/Epoxy Composite

Directory of Open Access Journals (Sweden)

MA Qiang

2016-09-01

Full Text Available An amphiphilic random copolymer of polyglycidyl methacrylate-co-N-vinyl carbazole P(GMA-co-NVC was synthesized by free radical polymerization and was used to noncovalently modify multi-walled carbon nanotubes (MWCNTs. The obtained P(GMA-co-NVC/MWCNTs was mixed with epoxy resin and used to reinforce epoxy resin. Polymer modified carbon nanotubes/epoxy resin composites were prepared by a casting molding method. Tensile test, electrical resistivity test and differential scanning calorimeter(DSC analysis were used to study the effect of polymer modified carbon nanotubes on the mechanical, electrical, and thermal properties of epoxy resin. The results show that the epoxy composite reinforced with P(GMA-co-NVC/MWCNTs shows a remarkable enhancement in both tensile strength and elongation at break compared to either the pure epoxy or the pristine MWCNTs/epoxy composites. In addition, the electrical conductivity of epoxy is significantly improved and the volume resistivity decreases from 1014Ω·m to 106Ω·m with 0.25% mass fraction loading of P(GMA-co-NVC/MWCNTs. Moreover, glass transition temperature of the epoxy composite also increases from 144℃ to 149℃.

Grimsel test site. Investigation phase VI. Pore space geometry project. Characterisation of pore space geometry by 14C-MMA impregnation

International Nuclear Information System (INIS)

Kelokaski, M.; Siitari-Kauppi, M.; Kauppi, I.; Hellmuth, K.-H.; Moeri, A.; Inderbitzin, L.; Biggin, C.; Kickmaier, W.; Martin, A.

2010-04-01

around 1 metre from the tunnel wall within a 20 cm injection interval. It was assumed that six additional smaller diameter radial boreholes would permit increased drying of the rock matrix and that intrusion of MMA would be observed from the observation boreholes during the injection of the resin. The two main differences between in situ and laboratory PMMA impregnations were: 1) drying in situ was done by ventilating warm air whereas in the laboratory, samples were dried by heating in a vacuum; 2) polymerisation in situ was through auto polymerisation whereas in the laboratory polymerisation was achieved by irradiation of the samples. It was found that air ventilation drying around the injection borehole was not effective enough to dry the rock matrix when 14 C-MMA impregnation was applied in situ. However, the penetration of 14 C-MMA into Grimsel granodiorite in situ was successful. Auto polymerisation of the resin reduced the amount of impregnation, but the thermal polymerisation succeeded well. The MMA intruded to depths of 2-5 cm from the injection borehole, with maximum penetration along the foliation of the rock texture. The amount of PMMA showed clearly a decreasing trend from injection borehole surface to a depth of 5 cm in the rock matrix. (authors)

Dermatosis profesional por resina epoxi: Presentación de un caso clínico Professional dermatosis for epoxy resin: A clinical case report

Directory of Open Access Journals (Sweden)

S Gaviola

2008-06-01

Full Text Available Mostramos un caso de dermatosis profesional originado por plásticos (resinas epoxi y la importancia de la detección precoz. Las resinas epoxi son de gran utilización en todo tipo de industrias (artes graficas, construcción, electrónica, componentes de prótesis traumatológicas, prótesis odontológicas, etc. y sus componentes pueden ser causa de dermatitis de contacto irritativa y por sensibilización.We describe a case of professional dermatosis caused by exposition to plastic products (epoxy resin and importance of early detection. The epoxy resins are widely used in all types of industries (graphics arts, construction, electronics, traumathological and odontological prothesis, etc. and their components may be the cause of contact dermatitis and sensitivity. Risk factors at work with epoxy resins are present during the production base resins, hardening agents, plasticizers and dilutants increase the risk of exposition at work. This requires preventive measures and early diagnosis.

Flammability studies of impregnated paper sheets

Science.gov (United States)

Ivan Simkovic; Anne Fuller; Robert White

2011-01-01

Paper sheets impregnated with flame retardants made from agricultural residues and other additives were studied with the cone calorimeter. The use of sugar beet ethanol eluent (SBE), CaCl2, and ZnCl2 lowered the peak rate of heat release (PRHR) the most in comparison to water treated material. The average effective heat of...

Multiscale Modeling of Carbon Nanotube-Epoxy Nanocomposites

Science.gov (United States)

Fasanella, Nicholas A.

Epoxy-composites are widely used in the aerospace industry. In order to improve upon stiffness and thermal conductivity; carbon nanotube additives to epoxies are being explored. This dissertation presents multiscale modeling techniques to study the engineering properties of single walled carbon nanotube (SWNT)-epoxy nanocomposites, consisting of pristine and covalently functionalized systems. Using Molecular Dynamics (MD), thermomechanical properties were calculated for a representative polymer unit cell. Finite Element (FE) and orientation distribution function (ODF) based methods were used in a multiscale framework to obtain macroscale properties. An epoxy network was built using the dendrimer growth approach. The epoxy model was verified by matching the experimental glass transition temperature, density, and dilatation. MD, via the constant valence force field (CVFF), was used to explore the mechanical and dilatometric effects of adding pristine and functionalized SWNTs to epoxy. Full stiffness matrices and linear coefficient of thermal expansion vectors were obtained. The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for the various nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. To obtain continuum-scale elastic properties from the MD data, multiscale modeling was considered to give better control over the volume fraction of nanotubes, and investigate the effects of nanotube alignment. Two methods were considered; an FE based method, and an ODF based method. The FE method probabilistically assigned elastic properties of elements from the MD lattice results based on the desired volume fraction and alignment of the nanotubes. For the ODF method, a distribution function was generated based on the desired amount of nanotube alignment

Titanium impregnated borosilicate zeolites for epoxidation catalysis

Czech Academy of Sciences Publication Activity Database

Přech, Jan; Vitvarová, Dana; Lupínková, Lenka; Kubů, Martin; Čejka, Jiří

2015-01-01

Roč. 212, AUG 2015 (2015), s. 28-34 ISSN 1387-1811 R&D Projects: GA ČR GAP106/11/0819 Institutional support: RVO:61388955 Keywords : borosilicate * titanium impregnation * epoxidation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.349, year: 2015

Combustion properties of wood impregnated with commercial ...

African Journals Online (AJOL)

The objective of this study was to determine some combustion properties of Calabrian pine (Pinus brutia Ten.) wood specimens impregnated with aqueous solutions of commercial fertilizers. Ammonium sulphate (AS) and diammonium phosphate (DAP) were used as commercial fertilizers. Diammonium phosphate and ...

Cure monitoring of epoxy resin by using fiber bragg grating sensor

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin Hyuk [KEPCO, Naju (Korea, Republic of); Kim, Dae Hyun [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2016-06-15

In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

Removal efficiency of radioactive methyl iodide on TEDA-impregnated activated carbons

International Nuclear Information System (INIS)

Gonzalez-Garcia, C.M.; Gonzalez, J.F.; Roman, S.

2011-01-01

Activated carbons were prepared by different series of carbon dioxide and steam activation from walnut shells for their optimal use as radioactive methyl iodide adsorbents in Nuclear Plants. The knowledge of the most favourable textural characteristics of the activated carbons was possible by the previous study of the commercial activated carbon currently used for this purpose. In order to increase their methyl iodide affinity, the effect of triethylenediamine impregnation was studied at 5 and 10 wt.%. The results obtained indicated that in both cases the adsorption efficiency is markedly improved by the addition of impregnant, which allows the adsorbate uptake to occur not only by physical adsorption, via non-specific interactions (as in non-impregnated carbons) but also by the specific interaction of triethylenediamine with radioactive methyl iodide. Methyl iodide retention efficiencies up to 98.1% were achieved. (author)

Rapid microwave processing of epoxy nanocomposites using carbon nanotubes

OpenAIRE

Luhyna, Nataliia; Inam, Fawad; Winnington, Ian

2013-01-01

Microwave processing is one of the rapid processing techniques for manufacturing nanocomposites. There is very little work focussing on the addition of CNTs for shortening the curing time of epoxy nanocomposites. Using microwave energy, the effect of CNT addition on the curing of epoxy nanocomposites was researched in this work. Differential scanning calorimetry (DSC) was used to determine the degree of cure for epoxy and nanocomposite samples. CNT addition significantly reduced the duration ...

Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

International Nuclear Information System (INIS)

Gantayat, S.; Rout, D.; Swain, S. K.

2016-01-01

The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increased with increasing concentration of f-MWCNTs.

Experimental design applied optimization of a state in epoxy clay dispersion

International Nuclear Information System (INIS)

Paz, Juliana D'Avila; Bertholdi, Jonas; Folgueras, Marilena Valadares; Pezin, Sergio Henrique; Coelho, Luiz Antonio Ferreira

2010-01-01

This paper presents some analysis showed that the exfoliation / intercalation of a montmorillonite clay in epoxy resin such as viscosity, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG). Increasing the viscosity of epoxy resin diglycidyl ether bisphenol A with the addition of clay associated with the sonification system at the time of dispersion is a good indication of exfoliation. The X-ray diffraction already cured composite shows a decrease of crystallinity of clay and EDS microanalysis of SEM, non-uniform dispersion of clay in epoxy resin. Thermal analysis TG composite clay / epoxy shows an increase in thermal stability relative to pure epoxy. (author)

Determinants of epoxy allergy in the construction industry: a case-control study.

Science.gov (United States)

Spee, Ton; Timmerman, Johan G; Rühl, Reinhold; Kersting, Klaus; Heederik, Dick J J; Smit, Lidwien A M

2016-05-01

Workers exposed to epoxy products are at risk of developing allergic contact dermatitis. To compare workers throughout the German construction industry with and without skin allergy to epoxy resins, hardeners, and/or reactive diluents, and to investigate which determinants are related to the development of epoxy allergy. A questionnaire was completed by 179 epoxy allergy cases, and 151 epoxy workers as controls. Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by the use of backwards stepwise logistic regression analysis. A multiple imputation approach was used to deal with missing data. Epoxy allergy was associated with an unusually high level of exposure to epoxy products [OR 2.13 (95%CI: 1.01-4.51)], wearing short sleeves or short trousers [OR 2.38 (95%CI: 1.03-5.52)], and not always using the correct type of gloves [OR 2.12 (95%CI: 1.12-4.01)]. A monotonic increasing risk was found with increasing exposure hours per week [OR 1.72 (95%CI: 1.39-2.14)]. Not using skin cream was inversely associated with epoxy allergy [OR 0.22 (95%CI: 0.08-0.59)]. Years working with epoxy products were inversely associated with epoxy allergy [OR 0.41 (95%CI: 0.27-0.61) per 10-year increase], suggesting a healthy worker survivor effect. Occupational epoxy allergy may be prevented by improving occupational hygiene behaviour and personal protection. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Conservation of diverse old wooden objects by impregnation and radiation curing

International Nuclear Information System (INIS)

Schaudy, R.; Slais, E.; Eibner, C.

1983-12-01

The conservation by impregnation with radiation-curable impregnating agents and subsequent curing with gamma radiation of an medieval wooden window-frame, several gold-coated frame fragments, a primitive flail and a poppy mallet as well as fragments of a painted mail-box and of a border is described and the results are discussed. The process is especially suited for the consolidation of heavily decayed porous objects, e.g. archaeologic findings. (Author) [de

Molecular Modeling of Aerospace Polymer Matrices Including Carbon Nanotube-Enhanced Epoxy

Science.gov (United States)

Radue, Matthew S.

Carbon fiber (CF) composites are increasingly replacing metals used in major structural parts of aircraft, spacecraft, and automobiles. The current limitations of carbon fiber composites are addressed through computational material design by modeling the salient aerospace matrix materials. Molecular Dynamics (MD) models of epoxies with and without carbon nanotube (CNT) reinforcement and models of pure bismaleimides (BMIs) were developed to elucidate structure-property relationships for improved selection and tailoring of matrices. The influence of monomer functionality on the mechanical properties of epoxies is studied using the Reax Force Field (ReaxFF). From deformation simulations, the Young's modulus, yield point, and Poisson's ratio are calculated and analyzed. The results demonstrate an increase in stiffness and yield strength with increasing resin functionality. Comparison between the network structures of distinct epoxies is further advanced by the Monomeric Degree Index (MDI). Experimental validation demonstrates the MD results correctly predict the relationship in Young's moduli for all epoxies modeled. Therefore, the ReaxFF is confirmed to be a useful tool for studying the mechanical behavior of epoxies. While epoxies have been well-studied using MD, there has been no concerted effort to model cured BMI polymers due to the complexity of the network-forming reactions. A novel, adaptable crosslinking framework is developed for implementing 5 distinct cure reactions of Matrimid-5292 (a BMI resin) and investigating the network structure using MD simulations. The influence of different cure reactions and extent of curing are analyzed on the several thermo-mechanical properties such as mass density, glass transition temperature, coefficient of thermal expansion, elastic moduli, and thermal conductivity. The developed crosslinked models correctly predict experimentally observed trends for various properties. Finally, the epoxies modeled (di-, tri-, and tetra

Epoxy modified bitumen : Chemical hardening and its interpretation

NARCIS (Netherlands)

Apostolidis, P.; Pipintakos, G.; van de Ven, M.F.C.; Liu, X.; Erkens, Sandra; Scarpas, Athanasios

2018-01-01

Epoxy modified bitumen (EMB) is a promising technology for long lasting paving materials ensuring higher resistance to rutting, oxygen- and moisture-induced damage. In this paper, an analysis of the chemical reactions that take place during the chemical hardening process (curing) of epoxy modified

Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

Directory of Open Access Journals (Sweden)

Artur Soares Cavalcanti Leal

2014-01-01

Full Text Available Nanocomposites of epoxy resin containing bentonite clay were fabricated to evaluate the thermomechanical behavior during heating. The epoxy resin system studied was prepared using bifunctional diglycidyl ether of bisphenol A (DGEBA, crosslinking agent diaminodiphenylsulfone (DDS, and diethylenetriamine (DETA. The purified bentonite organoclay (APOC was used in all experiments. The formation of nanocomposite was confirmed by X-ray diffraction analysis. Specimens of the fabricated nanocomposites were characterized by dynamic mechanical analysis (DMA. According to the DMA results a significant increase in glass transition temperature and storage modulus was evidenced when 1 phr of clay is added to epoxy resin.

Generalized morphea/eosinophilic fasciitis overlap after epoxy exposure

Directory of Open Access Journals (Sweden)

Warren H. Chan, MS

2018-03-01

Full Text Available Generalized morphea is associated with epoxy resin vapors and is characterized by the development of lesions shortly after exposure. Morphea presenting along with eosinophilic fasciitis (EF, or morphea/EF overlap, is rare and an indicator of poor prognosis and resistance to treatment. Here we present a case of generalized morphea/EF overlap linked to epoxy exposure. Our patient received multiple therapies—ultraviolet A1 phototherapy, prednisone, methotrexate, azathioprine, mycophenolate mofetil, cyclophosphamide, cyclosporine, and rituximab—none of which led to a significant response. The refractory nature of this disease warrants vigilance in its association with epoxy exposure.

Fabrication and characterization of TiO2-epoxy nanocomposite

International Nuclear Information System (INIS)

Chatterjee, Amit; Islam, Muhammad S.

2008-01-01

A systematic study has been conducted to investigate the matrix properties by introducing nanosize TiO 2 (5-40 nm, 0.5-2% by weight) fillers into an epoxy resin. Ultrasonic mixing process, via sonic cavitations, was employed to disperse the particles into the resin system. The thermal, mechanical, morphology and the viscoelastic properties of the nanocomposite and the neat resin were measured with TGA, DMA, TEM and Instron. The nano-particles are dispersed evenly throughout the entire volume of the resin. The nanofiller infusion improves the thermal, mechanical and viscoelastic properties of the epoxy resin. The nanocomposite shows increase in storage modulus, glass transition temperature, tensile modulus, flexural modulus and short beam shear strength from neat epoxy resin. The mechanical performance and thermal stability of the epoxy nanocomposites are depending on with the dispersion state of the TiO 2 in the epoxy matrix and are correlated with loading (0.0015-0.006% by volume). In addition, the nanocomposite shows enhanced flexural strength. Several reasons to explain these effects in terms of reinforcing mechanisms were discussed

Physical, structural and thermomechanical properties of oil palm nano filler/kenaf/epoxy hybrid nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Saba, N., E-mail: naheedchem@gmail.com [Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products(INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Paridah, M.T. [Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products(INTROP), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Abdan, K. [Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang Selangor (Malaysia); Ibrahim, N.A. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

2016-12-01

The present research study deals with the fabrication of kenaf/epoxy hybrid nanocomposites by the incorporation of oil palm nano filler, montmorillonite (MMT) and organically modified montmorillonite (OMMT) at 3% loading, through hand lay-up technique. Effect of adding different nano fillers on the physical (density), structural [X-ray diffraction (XRD)] and thermomechanical analysis (TMA) of kenaf/epoxy composites were carried out. Density results revealed that the incorporation of nano filler in the kenaf/epoxy composites increases the density which in turn increases the hardness of the hybrid nanocomposites. XRD analysis confirmed the presence of nano fillers in the structure of their respective fabricated hybrid nanocomposites. All hybrid nanocomposites displayed lower coefficient of thermal expansion (CTE) with respect to kenaf/epoxy composites. Overall results predicted that the properties improvement in nano OPEFB/kenaf/epoxy was quite comparable to MMT/kenaf/epoxy but relatively lesser to OMMT/kenaf/epoxy hybrid nanocomposites and higher with respect to kenaf/epoxy composites. The improvement ascribed due to improved interfacial bonding or cross linking between kenaf fibers and epoxy matrix by addition of nano filler. - Highlights: • Nano OPEFB/kenaf/epoxy hybrid nanocomposites were fabricated by hand lay-up. • Effect of nano OPEFB on density & structure of kenaf/epoxy were investigated. • Thermal expansion coefficients of kenaf/epoxy and hybrid nanocomposites evaluated. • Comparative studies were made with MMT and OMMT kenaf/epoxy hybrid nanocomposites.

Physical, structural and thermomechanical properties of oil palm nano filler/kenaf/epoxy hybrid nanocomposites

International Nuclear Information System (INIS)

Saba, N.; Paridah, M.T.; Abdan, K.; Ibrahim, N.A.

2016-01-01

The present research study deals with the fabrication of kenaf/epoxy hybrid nanocomposites by the incorporation of oil palm nano filler, montmorillonite (MMT) and organically modified montmorillonite (OMMT) at 3% loading, through hand lay-up technique. Effect of adding different nano fillers on the physical (density), structural [X-ray diffraction (XRD)] and thermomechanical analysis (TMA) of kenaf/epoxy composites were carried out. Density results revealed that the incorporation of nano filler in the kenaf/epoxy composites increases the density which in turn increases the hardness of the hybrid nanocomposites. XRD analysis confirmed the presence of nano fillers in the structure of their respective fabricated hybrid nanocomposites. All hybrid nanocomposites displayed lower coefficient of thermal expansion (CTE) with respect to kenaf/epoxy composites. Overall results predicted that the properties improvement in nano OPEFB/kenaf/epoxy was quite comparable to MMT/kenaf/epoxy but relatively lesser to OMMT/kenaf/epoxy hybrid nanocomposites and higher with respect to kenaf/epoxy composites. The improvement ascribed due to improved interfacial bonding or cross linking between kenaf fibers and epoxy matrix by addition of nano filler. - Highlights: • Nano OPEFB/kenaf/epoxy hybrid nanocomposites were fabricated by hand lay-up. • Effect of nano OPEFB on density & structure of kenaf/epoxy were investigated. • Thermal expansion coefficients of kenaf/epoxy and hybrid nanocomposites evaluated. • Comparative studies were made with MMT and OMMT kenaf/epoxy hybrid nanocomposites.

Enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide

Directory of Open Access Journals (Sweden)

B. Qi

2014-07-01

Full Text Available Graphene oxide (GO sheets were chemically grafted with thermotropic liquid crystalline epoxy (TLCP. Then we fabricated composites using TLCP-g-GO as reinforcing filler. The mechanical properties and thermal properties of composites were systematically investigated. It is found that the thermal and mechanical properties of the composites are enhanced effectively by the addition of fillers. For instance, the composites containing 1.0 wt% of TLCP-g-GO present impact strength of 51.43 kJ/m2, the tensile strength of composites increase from 55.43 to 80.85 MPa, the flexural modulus of the composites increase by more than 48%. Furthermore, the incorporation of fillers is effective to improve the glass transition temperature and thermal stability of the composites. Therefore, the presence of the TLCP-g-GO in the epoxy matrix could make epoxy not only stronger but also tougher.

Predicting the mechanical behaviour of Kevlar/epoxy and carbon/epoxy filament-wound tubes

Science.gov (United States)

Cazeneuve, C.; Joguet, P.; Maile, J. C.; Oytana, C.

1992-11-01

The axial, hoop and shear moduli and failure conditions of carbon/epoxy and Kevlar/epoxy filament-wound tubes have been determined through respective applications of internal pressure, tension and torsion. The introduction in the laminated plate theory of a gradual reduction in individual moduli makes it possible to overcome the limitations of the theory and enables accurate predictions to be made of the linear and non-linear stress/strain curves of 90 deg +/- 0/90 deg tubes. The existence of a dominant layer in the failure of the multilayered tubes has been shown experimentally. When associated with a failure criterion applied to the dominant layer, the new model permits the prediction of tube failure. Agreement between calculated and experimental data is better than 5 percent.

Optical emission behavior and radiation resistance of epoxy resins

International Nuclear Information System (INIS)

Kawanishi, Shunichi; Udagawa, Akira; Hagiwara, Miyuki

1987-11-01

To make clear a mechanism of radiation resistance of epoxy resin systems, a role of energy trapping site induced in bisphenol A type epoxy resins cured with 4 kinds of aromatic amines (Φ N ) was studied in comparison with the case of aliphatic amine curing system through a measurement of optical emission. In the system of the epoxy resin cured with DETA, the optical emission from an excited state of bisphenol A unit of epoxy resin and a charge transfer complex was observed. On the other hand, the optical emission from Φ N was observed in the aromatic amine curing system. Their excitation spectrum consists of peaks of absorption spectrum of BA and those of Φ N , showing that the excited state of Φ N is formed through the excitation of both BA and Φ N . Therefore, the excited energy of BA transfers to the excited state of Φ N . Emission intensity of Φ N band was 20 ∼ 100 times as large as that of BA. These results indicate that the radiation energy is effectively released as an optical emission from excited state of Φ N in the epoxy resin when cured with aromatic amine. It can be concluded from the above results that aromatic amine hardeners contribute to enhancement of the radiation resistance of epoxy resin by acting as an energy transfer agent. (author)

Epoxy encapsulant as serendipitous dosimeters during radiological/nuclear events

Energy Technology Data Exchange (ETDEWEB)

Barkyoumb, J.H. [Carderock Division, Naval Surface Warfare Center, 9500 MacArthur Blvd., West Bethesda, MD 20817-5700 (United States)], E-mail: jhbarky@earthlink.net; Mathur, V.K. [Carderock Division, Naval Surface Warfare Center, 9500 MacArthur Blvd., West Bethesda, MD 20817-5700 (United States)

2008-02-15

The radiation response of a smart chip (embedded integrated circuit) module has been reported earlier using the technique of optically stimulated luminescence (OSL). It was found that a smart chip module could be used to evaluate the personnel exposure in the accident dosimetry range. Through subsequent experiments, the radiation sensitivity of the chip module was traced to the epoxy encapsulant provided to protect the chip from the environment and physical damage and that the radiation sensitivity of the epoxy is due to the silica used as the 'filler' for controlling the thixotropic properties of the epoxy used for 'glob top' or 'dam-and-fill' encapsulation. It is desirable to retain the ability to use the smart chip as an accident dosimeter without requiring a modification of standard manufacturing process for which an infrastructure already exists to avoid additional costs. For this reason, we have investigated commercially available filled and unfilled epoxies both as received from the manufacturer and compared their response with epoxies to which commercial fillers are added. In this work we investigate the OSL response of various epoxies commonly used for potting of electronic circuits with and without various filler materials for their potential to be used as a casualty dosimeter in the exposure range of 0.5-10 Gy.

The investigation of copper-based impregnated activated carbons prepared from water-soluble materials for broad spectrum respirator applications

International Nuclear Information System (INIS)

Smith, J.W.H.; Westreich, P.; Abdellatif, H.; Filbee-Dexter, P.; Smith, A.J.; Wood, T.E.; Croll, L.M.; Reynolds, J.H.; Dahn, J.R.

2010-01-01

The preparation of impregnated activated carbons (IACs) from aqueous, copper-containing solutions for broad spectrum gas filtration applications is studied here. Several samples were studied to determine the effect that impregnant loading, impregnant distribution and impregnant recipe had on the overall performance. Dynamic flow testing was used to determine the gas filtration capacity of the IAC samples versus a variety of challenge gases. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were used to characterize the impregnant distribution on the carbon as a function of impregnant loading. Oven tests were performed to determine the thermal stability of the IAC samples exposed to elevated temperatures. The role impregnant distribution plays in gas filtration capacity and the overall performance of the IAC samples is discussed. The IAC samples prepared in this work were found to have gas filtration capacities as good as or better than broad spectrum respirator carbon samples prepared from the patent literature. IACs impregnated with an aqueous 2.4 M Cu(NO 3 ) 2 /0.04 M H 3 PO 4 .12MoO 3 /4 M HNO 3 solution that were heated to 200 deg. C under argon were found to have the best overall performance of the samples studied in this work.

Thick-target Pixe analysis of chromium, copper and arsenic impregnated lumber

International Nuclear Information System (INIS)

Saarela, K-E.; Harju, L.; Lill, J-O.; Rajander, J.; Lindroos, A.; Heselius, S-J.

1999-01-01

Chromium, copper and arsenic (CCA) have for decades been used for wood preservation. Of these elements especially arsenic is very toxic. As CCA impregnated wood is still today used for many construction purposes, a monitoring of these metal ions is of great environmental importance. Thick-target PIXE is a powerful method for the determination of trace metals in wood. The TTPIXE method enabled study of variations of the elemental concentrations in lumber treated with CCA impregnation solution. Distribution patterns were obtained for both naturally occurring elements and elements introduced in the treatment process. During the impregnation process a desorption of e.g. alkali metal ions takes place from the wood. The sensitivity of the method is improved by dry ashing of the samples prior to PIXE analysis. The TTPIXE method was calibrated and validated using international certified reference materials (CRM) based on wood material

Modeling boron separation from water by activated carbon, impregnated and unimpregnated

Energy Technology Data Exchange (ETDEWEB)

Ristic, M.; Grbavcic, Z. [Belgrade Univ., Belgrade (BA). Faculty of Technology and Metallurgy; Marinovic, V. [Belgrade Univ., Belgrade (BA). Ist. of Technical Science of the Serbian Academy of Science and Arts

2000-10-01

The sorption of boron from boric acid water solution by impregnated activated carbon has been studied. Barium, calcium, mannitol, tartaric acid and citric acid were used as chemical active materials. All processes were performed in a chromatographic continuous system at 22{sup 0} C. Experimental results show that activated carbon impregnated with mannitol is effective in removing boron from water. The separation of boron from the wastewater from a factory for producing enameled dishes by activated carbon impregnated with mannitol was also performed. Two models have been applied to describe published and new data on boron sorption by impregnated activated carbon. Both of them are based on the analysis of boron concentration response to the step input function. This led to a mathematical model that quite successfully described impregnation effects on adsorption capacities. [Italian] E' stato studiato l'assorbimento del boro, mediante carbone attivo impregnato, da soluzioni acquose di acido borico. Quali materiali chimici attivi sono stati utilizzati: bario, calcio, mannitolo, acido tartarico ed acido citrico. Tutti i processi sono stati condotti in un sistema cromatografico continuo a 22{sup 0}C. I risultati sperimentali mostrano che il carbone attivo impregnato con mannitolo e' efficace nella rimozione del boro dall'acqua. E' anche stata effettuata la separazione del boro da acque di scarico di un'industria per la produzione di piatti smaltati mediante carbone attivo impregnato con mannitolo. Sono stati applicati due modelli per descrivere i risultati, pubblicati e nuovi, dell'assorbimento del boro mediante carbone attivo impregnato. Entrambi sono basati sull'analisi della risposta alla concentrazione di boro successivamente incrementata a stadi. Cio' porta ad un modello matematico che descrive abbastanza soddisfacentemente gli effetti dell'impregnazione sulla capacita' di assorbimento.

Monomer-Polymer Chemistry and the Impregnation Process

Energy Technology Data Exchange (ETDEWEB)

Stannett, V. [North Carolina State University, Raleigh, NC (United States)

1968-10-15

A brief outline of early polymerization techniques is followed by a description of polymerization process chemistry, impregnation and polymerization methods and criteria for the choice of monomer. General considerations, including the effects of polymerization inhibitors, swelling agents, radiation dose rate and sample thickness, are enumerated. (author)

Prevalent material parameters governing spalling of a slag-impregnated refractory

Energy Technology Data Exchange (ETDEWEB)

Blond, E.; Schmitt, N.; Arnould, O.; Hild, F. [LMT-Cachan (ENS de Cachan / CNRS-UMR 8535 / Univ. Paris 6), Cachan (France); Blumenfeld, P. [CRDM / ARCELOR Grande Synthe, Dunkerque (France); Poirier, J. [CRDM / ARCELOR Grande Synthe, Dunkerque (France); CRMHT-CNRS, Orleans (France)

2004-07-01

In steel ladle linings, bauxite refractories in contact with iron and steel slag are subjected to complex loadings. To identify the causes of degradation in different reactor linings, a coupling diagram made up of three poles is established: namely, slag impregnation (I), Thermomechanics (TM) and phase transformations (P). The variation of the microstructure and the gradient of the chemical composition resulting from the (I-P) coupling are characterized by microprobe analyses; a natural impregnation tracer is identified. The (I-T) coupling is studied by modeling the refractory lining behavior subjected to a cyclic thermal loading within the framework of the mechanics of porous continua. Parameters governing the location and amplitude of the maximum pore pressure are obtained and their influences are studied. The analysis of the (TM) pole leads to the identification of a thermo-elasto-viscoplastic model for bauxite in various states of slag impregnation. Numerical simulations show that the stress state developed during the heating stages can induce spalling, probably generated by a localized over-pressure of slag. (orig.)

Conservation of mining and metallurgic arachaeologic wooden objects by impregnation and radiation curing

International Nuclear Information System (INIS)

Schaudy, R.; Slais, E.; Eibner, C.

1983-05-01

The conservation of mining and metallurgic archaeologic wooden objects of different grade of destruction by impregnation with radiation-curable impregnating agents followed by in-situ-curing with gamma rays is described. Dry objects have been consolidated after cautious cleaning, whereas wet findings had to be freezedried first. The results are discussed. (Author) [de

Friction and wear behavior of nanosilica-filled epoxy resin composite coatings

International Nuclear Information System (INIS)

Kang Yingke; Chen Xinhua; Song Shiyong; Yu Laigui; Zhang Pingyu

2012-01-01

Hydrophilic silica nanoparticles (abridged as nano-SiO 2 ) surface-capped with epoxide were dispersed in the solution of epoxy resin (abridged as EP) in tetrahydrofuran under magnetic stirring. Resultant suspension of nano-SiO 2 in EP was then coated onto the surface of glass slides and dried at 80 °C in a vacuum oven for 2 h, generating epoxy resin-nanosilica composite coatings (coded as EP/nano-SiO 2 ). EP coating without nano-SiO 2 was also prepared as a reference in the same manner. A water contact angle meter and a surface profiler were separately performed to measure the water contact angles and surface roughness of as-prepared EP/nano-SiO 2 composite coatings. The friction and wear behavior of as-prepared EP/nano-SiO 2 composite coatings sliding against steel in a ball-on-plate contact configuration under unlubricated condition was evaluated. Particularly, the effect of coating composition on the friction and wear behavior of the composite coatings was highlighted in relation to their microstructure and worn surface morphology examined by means of scanning electron microscopy. Results indicate that EP/nano-SiO 2 composite coatings have a higher surface roughness and water contact angle than EP coating. The EP-SiO 2 coatings doped with a proper amount of hydrophilic SiO 2 nanoparticles show lower friction coefficient than EP coating. However, the introduction of surface-capped nanosilica as the filler results in inconsistent change in the friction coefficient and wear rate of the filled EP-matrix composites; and it needs further study to achieve well balanced friction-reducing and antiwear abilities of the composite coatings for tribological applications.

Evaluation of epoxy resin for cryogenic use by positron annihilation method. Change of characteristics of epoxy resin with cross-linking density and positron lifetime

International Nuclear Information System (INIS)

Nishijima, Shigehiro; Honda, Yoshihide; Okada, Toichi; Kobayashi, Yoshinori; Namba, Shingo.

1994-01-01

The positron annihilation method has been applied to evaluate unoccupied space in epoxy aiming at the design of the molecular structure for cryogenic use. To confirm the model in which molecular free space is needed in the epoxy for cryogenic use, the molecular weight between cross-linkings in epoxy was changed. The increase of molecular weight between cross-linkings brought an increase of fracture toughness even at liquid helium temperature and the model was found to be confirmed. The increase of molecular weight between cross-linkings was also found to decrease the 3rd lifetime of positrons. It suggested that the epoxy main chains were folded and this was confirmed by the molecular mechanical calculation. (author)

Thermal conductivity of pillared graphene-epoxy nanocomposites using molecular dynamics

Science.gov (United States)

Lakshmanan, A.; Srivastava, S.; Ramazani, A.; Sundararaghavan, V.

2018-04-01

Thermal conductivity in a pillared graphene-epoxy nanocomposite (PGEN) is studied using equilibrium molecular dynamics simulations. PGEN is a proposed material for advanced thermal management applications because it combines high in-plane conductivity of graphene with high axial conductivity of a nanotube to significantly enhance the overall conductivity of the epoxy matrix material. Anisotropic conductivity of PGEN has been compared with that of pristine and functionalized carbon nanotube-epoxy nanocomposites, showcasing the advantages of the unique hierarchical structure of PGEN. Compared to pure carbon allotropes, embedding the epoxy matrix also promotes a weaker dependence of conductivity on thermal variations. These features make this an attractive material for thermal management applications.

Spatial repellency of metofluthrin-impregnated multilayer paper strip against Aedes albopictus under outdoor conditions, Nagasaki, Japan

OpenAIRE

Argueta, Tamara Belzabel Obispo; Kawada, Hitoshi; Takagi, Masahiro

2004-01-01

Spatial repellency of a new device in which metofluthrin, a newly synthesized pyrethroid, is impregnated into a multilayer paper strip, against Aedes albopictus was evaluated under outdoor conditions. High spatial repellency (>80%) with the metofluthrin-impregnated (200 mg) device lasted for more than 6 weeks, while the repellency with the same device impregnated with the same amount of transfluthrin declined within 5 weeks after treatment.

Anti-biofilm and cytotoxicity activity of impregnated dressings with silver nanoparticles

International Nuclear Information System (INIS)

Velázquez-Velázquez, Jorge Luis; Santos-Flores, Andrés; Araujo-Meléndez, Javier; Sánchez-Sánchez, Roberto; Velasquillo, Cristina; González, Carmen; Martínez-Castañon, Gabriel; Martinez-Gutierrez, Fidel

2015-01-01

Infections arising from bacterial adhesion and colonization on chronic wounds are a significant healthcare problem. Silver nanoparticles (AgNPs) impregnated in dressing have attracted a great deal of attention as a potential solution. The goal of the present study was to evaluate the anti-biofilm activities of AgNPs impregnated in commercial dressings against Pseudomonas aeruginosa, bacteria isolated of chronic wounds from a hospital patient. The antimicrobial activity of AgNPs was tested within biofilms generated under slow fluid shear conditions using a standard bioreactor. A 2-log reduction in the number of colony-forming units of P. aeruginosa was recorded in the reactor on exposure to dressing impregnated with 250 ppm of AgNPs, diameter 9.3 ± 1.1 nm, and also showed compatibility to mammalian cells (human fibroblasts). Our study suggests that the use of dressings with AgNPs may either prevent or reduce microbial growth in the wound environment, and reducing wound bioburden may improve wound-healing outcomes. - Highlights: • Biological activities of silver nanoparticles for wound-healing purposes • Characterization of the silver nanoparticles impregnated in dressings • Reduction in the P. aeruginosa biofilm formation was statistically significant. • Compatibility to human dermal fibroblasts as the main cell type involved in the reparation • AgNPs covering the surfaces would provide great potential for prevention and treatment

Anti-biofilm and cytotoxicity activity of impregnated dressings with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Velázquez-Velázquez, Jorge Luis [Laboratorio de Microbiología, Facultad de Ciencias Químicas, UASLP (Mexico); Santos-Flores, Andrés; Araujo-Meléndez, Javier [Servicio de Epidemiología del Hospital Central “Dr. Ignacio Morones Prieto”, San Luis Potosí (Mexico); Sánchez-Sánchez, Roberto; Velasquillo, Cristina [Laboratorio de Biotecnología, Instituto Nacional de Rehabilitación (Mexico); González, Carmen [Laboratorio de Fisiología Celular, Facultad de Ciencias Químicas, UASLP (Mexico); Martínez-Castañon, Gabriel [Maestría en Ciencias Odontológicas Facultad de Estomatología, UASLP (Mexico); Martinez-Gutierrez, Fidel, E-mail: fidel@uaslp.mx [Laboratorio de Microbiología, Facultad de Ciencias Químicas, UASLP (Mexico)

2015-04-01

Infections arising from bacterial adhesion and colonization on chronic wounds are a significant healthcare problem. Silver nanoparticles (AgNPs) impregnated in dressing have attracted a great deal of attention as a potential solution. The goal of the present study was to evaluate the anti-biofilm activities of AgNPs impregnated in commercial dressings against Pseudomonas aeruginosa, bacteria isolated of chronic wounds from a hospital patient. The antimicrobial activity of AgNPs was tested within biofilms generated under slow fluid shear conditions using a standard bioreactor. A 2-log reduction in the number of colony-forming units of P. aeruginosa was recorded in the reactor on exposure to dressing impregnated with 250 ppm of AgNPs, diameter 9.3 ± 1.1 nm, and also showed compatibility to mammalian cells (human fibroblasts). Our study suggests that the use of dressings with AgNPs may either prevent or reduce microbial growth in the wound environment, and reducing wound bioburden may improve wound-healing outcomes. - Highlights: • Biological activities of silver nanoparticles for wound-healing purposes • Characterization of the silver nanoparticles impregnated in dressings • Reduction in the P. aeruginosa biofilm formation was statistically significant. • Compatibility to human dermal fibroblasts as the main cell type involved in the reparation • AgNPs covering the surfaces would provide great potential for prevention and treatment.

Thermoset Blends of an Epoxy Resin and Polydicyclopentadiene

Energy Technology Data Exchange (ETDEWEB)

Rohde, Brian J.; Le, Kim Mai; Krishnamoorti, Ramanan; Robertson, Megan L.

2016-12-13

The mechanical properties of two chemically distinct and complementary thermoset polymers were manipulated through development of thermoset blends. The thermoset blend system was composed of an anhydride-cured diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin, contributing high tensile strength and modulus, and polydicyclopentadiene (PDCPD), which has a higher toughness and impact strength as compared to other thermoset polymers. Ultra-small-angle and small-angle X-ray scattering analysis explored the morphology of concurrently cured thermoset blends, revealing a macroscopically phase separated system with a surface fractal structure across blended systems of varying composition. The epoxy resin rich and PDCPD rich phases exhibited distinct glass transitions (Tg’s): the Tg observed at higher temperature was associated with the epoxy resin rich phase and was largely unaffected by the presence of PDCPD, whereas the PDCPD rich phase Tg systematically decreased with increasing epoxy resin content due to inhibition of dicyclopentadiene ring-opening metathesis polymerization. The mechanical properties of these phase-separated blends were in reasonable agreement with predictions by the rule of mixtures for the blend tensile strength, modulus, and fracture toughness. Scanning electron microscopy analysis of the tensile and fracture specimen fracture surfaces showed an increase in energy dissipation mechanisms, such as crazing, shear banding, and surface roughness, as the fraction of the more ductile component, PDPCD, increased. These results present a facile method to tune the mechanical properties of a toughened thermoset network, in which the high modulus and tensile strength of the epoxy resin can be largely retained at high epoxy resin content in the blend, while increasing the fracture toughness.

Properties of carbonisation products obtained from impregnated coal

Czech Academy of Sciences Publication Activity Database

Plevová, Eva; Šugárková, Věra; Kaloč, M.; Vaculíková, Lenka

-, - (2008), s. 52-61. ISBN 978-80-248-1939-6 Grant - others:GA CŘ(CZ) GA105/00/1698 Institutional research plan: CEZ:AV0Z30860518 Keywords : chlorides * impregnation * coal Subject RIV: CC - Organic Chemistry

Self-healing woven glass fabric/epoxy composites with the healant consisting of micro-encapsulated epoxy and latent curing agent

International Nuclear Information System (INIS)

Yin Tao; Zhou Lin; Rong Minzhi; Zhang Mingqiu

2008-01-01

This paper reports a study of self-healing woven glass fabric reinforced epoxy composites. The healing agent was a two-component one synthesized in the authors' laboratory, which consisted of epoxy-loaded urea-formaldehyde microcapsules as the polymerizable binder and CuBr 2 (2-methylimidazole) 4 (CuBr 2 (2-MeIm) 4 ) as the latent hardener. Both the microcapsules and the matching catalyst were pre-embedded and pre-dissolved in the composites' matrix, respectively. When the microcapsules are split by propagating cracks, the uncured epoxy can be released into the damaged areas and then consolidated under the catalysis of CuBr 2 (2-MeIm) 4 that was homogeneously distributed in the composites' matrix on a molecular scale. As a result, the cracked faces can be bonded together. The influence of the content of the self-healing agent on the composites' tensile properties, interlaminar fracture toughness and healing efficiency was evaluated. It was found that a healing efficiency over 70% relative to the fracture toughness of virgin composites was obtained in the case of 30 wt% epoxy-loaded microcapsules and 2 wt% latent hardener

Impregnated cathode coated with tungsten thin film containing Sc2O3

International Nuclear Information System (INIS)

Yamamoto, S.; Taguchi, S.; Watanabe, I.; Kawase, S.

1987-01-01

An impregnated cathode of a novel structure is proposed, fabricated, and evaluated. A thin tungsten film 100--400 nm in thickness containing various amounts of Sc 2 O 3 is coated on a standard impregnated cathode composed of a porous tungsten body in which electron emissive materials are impregnated. The electron emission property measured with a diode configuration is found to be dependent on Sc 2 O 3 content and surface atom distribution. Surface atom distribution is depicted by means of Auger electron spectroscopy. For high electron emission enhancement it is necessary for Sc 2 O 3 content to be 2.5--6.5 wt. % and for a layer of the order of a monolayer in thickness composed of Ba, Sc, and O to develop on the cathode surface

Dielectric properties of transformer paper impregnated by mineral oil based magnetic fluid

International Nuclear Information System (INIS)

Timko, M; Marton, K; Tomco, L; Kopcansky, P; Koneracka, M

2010-01-01

The influence of combined magnetic and electric field on permittivity of transformer paper used in power transformers was observed. Transformer paper was impregnated by pure transformer oil ITO 100 and magnetic fluids based on transformer oil ITO 100 with different concentrations of magnetite nanoparticles. The measurements were carried out with help of high precision capacitance bridge. The electric intensity between circular planar electrodes was in the region of weak electric field (E > 10 6 V/m). The increase of electric permittivity of transformer paper impregnated by magnetic fluid opposite pure transformer paper was observed. The experiments showed that permittivity of insulator system consisting of pure transformer paper and impregnated transformer paper naturally depends on number of paper layers. The magnetodielectric effect was found to be dependent on magnetite nanoparticles concentration in magnetic fluids.

Dielectric microwave absorbing material processed by impregnation of carbon fiber fabric with polyaniline

Directory of Open Access Journals (Sweden)

Luiza de Castro Folgueras

2007-03-01

Full Text Available It is a known fact that the adequate combination of components and experimental conditions may produce materials with specific requirements. This study presents the effect of carbon fiber fabric impregnation with polyaniline conducting polymer aiming at the radar absorbing material processing. The experiments consider the sample preparation with one and two impregnations. The prepared samples were evaluated by reflectivity measurements, in the frequency range of 8-12 GHz and scanning electron microscopy analyses. The correlation of the results shows that the quantity of impregnated material influences the performance of the processed microwave absorber. This study shows that the proposed experimental route provides flexible absorbers with absorption values of the incident radiation close to 87%.

An in vitro Method for Predicting Inhalation Toxicity of Impregnation Spray Products

DEFF Research Database (Denmark)

Sørli, Jorid B.; Hansen, Jitka S.; Nørgaard, Asger Wisti

2015-01-01

Impregnation spray products are used for making surfaces water and dirt repellent. The products are composed of one or more active film-forming components dissolved or suspended in an appropriate solvent mixture. Exposure to impregnation spray products may cause respiratory distress and new cases...

The investigation of copper-based impregnated activated carbons prepared from water-soluble materials for broad spectrum respirator applications

Energy Technology Data Exchange (ETDEWEB)

Smith, J.W.H.; Westreich, P.; Abdellatif, H.; Filbee-Dexter, P.; Smith, A.J. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 3J5 (Canada); Wood, T.E. [3M Company, St. Paul, MN, 55144 (United States); Croll, L.M.; Reynolds, J.H. [3M Canada Company, Brockville, Ontario, K6V 5V8 (Canada); Dahn, J.R., E-mail: jeff.dahn@dal.ca [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 3J5 (Canada); Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3 (Canada)

2010-08-15

The preparation of impregnated activated carbons (IACs) from aqueous, copper-containing solutions for broad spectrum gas filtration applications is studied here. Several samples were studied to determine the effect that impregnant loading, impregnant distribution and impregnant recipe had on the overall performance. Dynamic flow testing was used to determine the gas filtration capacity of the IAC samples versus a variety of challenge gases. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were used to characterize the impregnant distribution on the carbon as a function of impregnant loading. Oven tests were performed to determine the thermal stability of the IAC samples exposed to elevated temperatures. The role impregnant distribution plays in gas filtration capacity and the overall performance of the IAC samples is discussed. The IAC samples prepared in this work were found to have gas filtration capacities as good as or better than broad spectrum respirator carbon samples prepared from the patent literature. IACs impregnated with an aqueous 2.4 M Cu(NO{sub 3}){sub 2}/0.04 M H{sub 3}PO{sub 4}.12MoO{sub 3}/4 M HNO{sub 3} solution that were heated to 200 deg. C under argon were found to have the best overall performance of the samples studied in this work.

Fabrication and mechanical properties of multi-walled carbon nanotubes/epoxy nanocomposites

International Nuclear Information System (INIS)

Yeh, M.-K.; Hsieh, T.-H.; Tai, N.-H.

2008-01-01

Carbon nanotubes have better physical and mechanical behavior than the traditional materials. In this study, the multi-walled carbon nanotubes (MWNTs) were added to the epoxy resin as a reinforcement to fabricate MWNTs/epoxy nanocomposites. The pressure and temperature were applied to cure the MWNTs/epoxy compound by hot press method. Mechanical properties such as tensile strength, Young's modulus, and Poisson's ratio were measured. The effect of weight percentages of the MWNTs was investigated. Morphologies of the fracture surface of MWNTs/epoxy nanocomposites were observed by scanning electron microscope

Leybold vacuum handbook

CERN Document Server

Diels, K; Diels, Kurt

1966-01-01

Leybold Vacuum Handbook presents a collection of data sets that are essential for numerical calculation of vacuum plants and vacuum processes. The title first covers vacuum physics, which includes gas kinetics, flow phenomena, vacuum gauges, and vapor removal. Next, the selection presents data on vacuum, high vacuum process technology, and gas desorption and gettering. The text also deals with materials, vapor pressure, boiling and melting points, and gas permeability. The book will be of great interest to engineers and technicians that deals with vacuum related technologies.

Stronger Fire-Resistant Epoxies

Science.gov (United States)

Fohlen, George M.; Parker, John A.; Kumar, Devendra

1988-01-01

New curing agent improves mechanical properties and works at lower temperature. Use of aminophenoxycyclotriphosphazene curing agents yields stronger, more heat- and fire-resistant epoxy resins. Used with solvent if necessary for coating fabrics or casting films.

Vacuum Technology

Energy Technology Data Exchange (ETDEWEB)

Biltoft, P J

2004-10-15

The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.

Indian Vacuum Society: The Indian Vacuum Society

Science.gov (United States)

Saha, T. K.

2008-03-01

The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

Active corrosion protection performance of an epoxy coating applied on the mild steel modified with an eco-friendly sol-gel film impregnated with green corrosion inhibitor loaded nanocontainers

Science.gov (United States)

Izadi, M.; Shahrabi, T.; Ramezanzadeh, B.

2018-05-01

In this study the corrosion resistance, active protection, and cathodic disbonding performance of an epoxy coating were improved through surface modification of steel by a hybrid sol-gel system filled with green corrosion inhibitors loaded nanocontainer as intermediate layer on mild steel substrate. The green inhibitor loaded nanocontainers (GIN) were used to induce active inhibition performance in the protective coating system. The corrosion protection performance of the coated panels was investigated by electrochemical impedance spectroscopy (EIS), salt spray, and cathodic disbonding tests. It was observed that the corrosion inhibition performance of the coated mild steel panels was significantly improved by utilization of active multilayer coating system. The inhibitor release from nanocontainers at the epoxy-silane film/steel interface resulted in the anodic and cathodic reactions restriction, leading to the lower coating delamination from the substrate and corrosion products progress. Also, the active inhibition performance of the coating system was approved by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDS) analysis on the panels with artificial defects. The inhibitive agents were released to the scratch region and blocked the active sites on the metal surface.

Fullerene–epoxy nanocomposites-enhanced mechanical properties at low nanofiller loading

International Nuclear Information System (INIS)

Rafiee, Mohammad A.; Yavari, Fazel; Rafiee, Javad; Koratkar, Nikhil

2011-01-01

In this study, we characterized the mechanical properties of fullerence (C 60 ) epoxy nanocomposites at various weight fractions of fullerene additives in the epoxy matrix. The mechanical properties measured were the Young’s modulus, ultimate tensile strength, fracture toughness, fracture energy, and the material’s resistance to fatigue crack propagation. All of the above properties of the epoxy polymer were significantly enhanced by the fullerene additives at relatively low nanofiller loading fractions (∼0.1 to 1% of the epoxy matrix weight). By contrast, other forms of nanoparticle fillers such as silica, alumina, and titania nanoparticles require up to an order of magnitude higher weight fraction to achieve comparable enhancement in properties.

Thermal properties of oil palm nano filler/kenaf reinforced epoxy hybrid nanocomposites

Science.gov (United States)

Saba, N.; Paridah, M. T.; Abdan, K.; Ibrahim, N. A.

2016-11-01

The aim of this research study was to fabricate nano oil palm empty fruit bunch (OPEFB)/kenaf/epoxy hybrid nanocomposites and to make comparative study on the thermal properties of nano OPEFB/kenaf/epoxy hybrid nanocomposites with the montmorillonite (MMT)/kenaf/epoxy hybrid nanocomposites and organically modified MMT (OMMT)/kenaf/epoxy hybrid nanocomposites. Epoxy based kenaf hybrid nanocomposites was prepared by dispersing the nano filler (nano OPEFB filler, MMT, OMMT) at 3% loading through high speed mechanical stirrer followed by hand lay-up technique. Thermal properties of hybrid nanocomposites were analyzed through thermogravimetry analyzer (TGA), and differential scanning calorimetry (DSC). Obtained results specified that addition of nano OPEFB filler improves the thermal stability and char yield of kenaf/epoxy composites. Furthermore, the increase in decomposition temperature by the nano OPEFB filler was quite comparable to the MMT/kenaf/epoxy but relatively less than OMMT/kenaf/epoxy hybrid nanocomposites. We concluded from overall consequences that the nano OPEFB filler can be used as the promising and innovative alternative of existing expensive nano filler, with relatively lesser impact on the environment having marked pronounced impact on the construction, automotive, aerospace, electronics and semiconducting sectors as future industries based on bio-wastes with satisfactory light weight and thermal stability on other side.

Stochastic estimation of acoustic impedance of glass-reinforced epoxy coating 128-134

Energy Technology Data Exchange (ETDEWEB)

Kim, No Hyu [School of MechatronicEngineering, Korea University of Technology and Education, Chunan (Korea, Republic of); Nah, Hwan Seon [Structural Engineering Lab., Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2014-04-15

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

Stochastic estimation of acoustic impedance of glass-reinforced epoxy coating 128-134

International Nuclear Information System (INIS)

Kim, No Hyu; Nah, Hwan Seon

2014-01-01

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

Hansen solubility parameters for a carbon fiber/epoxy composite

DEFF Research Database (Denmark)

Launay, Helene; Hansen, Charles M.; Almdal, Kristoffer

2007-01-01

In this study, the physical affinity between an epoxy matrix and oxidized, unsized carbon fibers has been evaluated using Hansen solubility (cohesion) parameters (HSP). A strong physical compatibility has been shown, since their respective HSP are close. The use of a glassy carbon substrate...... as a model for unsized carbon fiber has been demonstrated as appropriate for the study of interactions between the materials in composite carbon fiber-epoxy systems. The HSP of glassy carbon are similar to those of carbon fibers and epoxy matrix. (C) 2007 Elsevier Ltd. All rights reserved....

Electrical and Mechanical Properties of 3D-Printed Graphene-Reinforced Epoxy

Science.gov (United States)

Compton, Brett G.; Hmeidat, Nadim S.; Pack, Robert C.; Heres, Maximilian F.; Sangoro, Joshua R.

2018-03-01

Recent developments in additive manufacturing have demonstrated the potential for thermoset polymer feedstock materials to achieve high strength, stiffness, and functionality through incorporation of structural and functional filler materials. In this work, graphene was investigated as a potential filler material to provide rheological properties necessary for direct-write three-dimensional (3D) printing and electrostatic discharge properties to the printed component. The rheological properties of epoxy/graphene mixtures were characterized, and printable epoxy/graphene inks formulated. Sheet resistance values for printed epoxy/graphene composites ranged from 0.67 × 102 Ω/sq to 8.2 × 103 Ω/sq. The flexural strength of printed epoxy/graphene composites was comparable to that of cast neat epoxy ( 80 MPa), suggesting great potential for these new materials in multifunctional 3D-printed devices.

Degradation of modified carbon black/epoxy nanocomposite coatings under ultraviolet exposure

International Nuclear Information System (INIS)

Ghasemi-Kahrizsangi, Ahmad; Shariatpanahi, Homeira; Neshati, Jaber; Akbarinezhad, Esmaeil

2015-01-01

Graphical abstract: - Highlights: • Degradation behavior of modified Carbon Black (CB) epoxy coating was studied under UV irradiation using based on EIS technique. • By using SDS as a surfactant, nano particles of CB were uniformly dispersed in an epoxy matrix. • ATR-FTIR analysis showed that the CB coatings were degraded less than epoxy coating. • EIS results showed the coating with 2.5 wt% CB nanoparticles had higher corrosion resistance than neat epoxy. - Abstract: Degradation of epoxy coatings with and without Carbon Black (CB) nanoparticles under ultraviolet (UV) radiation were investigated using electrochemical impedance spectroscopy (EIS). Sodium dodecyl sulfate (SDS) was used to obtain a good dispersion of CB nanoparticles in a polymer matrix. TEM analysis proved a uniform dispersion of modified CB nanoparticles in epoxy coating. The coatings were subjected to UV radiation to study the degradation behavior and then immersed in 3.5 wt% NaCl. The results showed that the electrochemical behavior of neat epoxy coating was related to the formation and development of microcracks on the surface. The occurrence of microcracks on the surface of the coatings and consequently the penetration of ionic species reduced by adding CB nanoparticles into the formulation of the coatings. CB nanoparticles decreased degradation of CB coatings by absorbing UV irradiation. The ATR-FTIR results showed that decrease in the intensity of methyl group as main peak in presence of 2.5 wt% CB was lower than neat epoxy. In addition, the reduction in impedance of neat epoxy coating under corrosive environment was larger than CB coatings. The CB coating with 2.5 wt% nanoparticles had the highest impedance to corrosive media after 2000 h UV irradiation and 24 h immersion in 3.5 wt% NaCl.

Degradation of modified carbon black/epoxy nanocomposite coatings under ultraviolet exposure

Energy Technology Data Exchange (ETDEWEB)

Ghasemi-Kahrizsangi, Ahmad, E-mail: ahmad_usk@yahoo.com [Corrosion Department, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Shariatpanahi, Homeira, E-mail: shariatpanahih@ripi.ir [Coating Research Center, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Neshati, Jaber [Corrosion Department, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Akbarinezhad, Esmaeil [Coating Research Center, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of)

2015-10-30

Graphical abstract: - Highlights: • Degradation behavior of modified Carbon Black (CB) epoxy coating was studied under UV irradiation using based on EIS technique. • By using SDS as a surfactant, nano particles of CB were uniformly dispersed in an epoxy matrix. • ATR-FTIR analysis showed that the CB coatings were degraded less than epoxy coating. • EIS results showed the coating with 2.5 wt% CB nanoparticles had higher corrosion resistance than neat epoxy. - Abstract: Degradation of epoxy coatings with and without Carbon Black (CB) nanoparticles under ultraviolet (UV) radiation were investigated using electrochemical impedance spectroscopy (EIS). Sodium dodecyl sulfate (SDS) was used to obtain a good dispersion of CB nanoparticles in a polymer matrix. TEM analysis proved a uniform dispersion of modified CB nanoparticles in epoxy coating. The coatings were subjected to UV radiation to study the degradation behavior and then immersed in 3.5 wt% NaCl. The results showed that the electrochemical behavior of neat epoxy coating was related to the formation and development of microcracks on the surface. The occurrence of microcracks on the surface of the coatings and consequently the penetration of ionic species reduced by adding CB nanoparticles into the formulation of the coatings. CB nanoparticles decreased degradation of CB coatings by absorbing UV irradiation. The ATR-FTIR results showed that decrease in the intensity of methyl group as main peak in presence of 2.5 wt% CB was lower than neat epoxy. In addition, the reduction in impedance of neat epoxy coating under corrosive environment was larger than CB coatings. The CB coating with 2.5 wt% nanoparticles had the highest impedance to corrosive media after 2000 h UV irradiation and 24 h immersion in 3.5 wt% NaCl.

Adhesive properties and adhesive joints strength of graphite/epoxy composites

Science.gov (United States)

Rudawska, Anna; Stančeková, Dana; Cubonova, Nadezda; Vitenko, Tetiana; Müller, Miroslav; Valášek, Petr

2017-05-01

The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces. Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure. The single-lap adhesive joints of epoxy composites were considered. Adhesive properties were described by surface free energy. Owens-Wendt method was used to determine surface free energy. The epoxy two-component adhesive was used to preparing the adhesive joints. Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites. The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (0.48 mm). Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level). It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy.

Mechanical properties of multi-walled carbon nanotube/epoxy polysulfide nanocomposite

International Nuclear Information System (INIS)

Shirkavand Hadavand, Behzad; Mahdavi Javid, Kimya; Gharagozlou, Mehrnaz

2013-01-01

Highlights: ► Preparation of epoxy polysulfide nanocomposite. ► Multi-walled carbon nanotubes have been modified and dispersed in epoxy polysulfide matrix. ► Mechanical properties of MWNT/epoxy polysulfide have been studied. - Abstract: In this research, multi-walled carbon nanotubes (MWCNTs) were modified by acid functionalization (H 2 SO 4 :HNO 3 = 1:3 by volume) and then mechanical properties of reinforced epoxy polysulfide resin by the both pure and treated MWNTs have been evaluated. For achieving this goal, different weight percentages of pure and treated MWCNT (0.1–0.3 wt%) were dispersed in the epoxy polysulfide resin separately and then mixed with curing agent. Experimental results have shown significant difference between acid treated and untreated MWCNTs in mechanical properties of epoxy polysulfide nanocomposites. In nanocomposite with 0.1–0.3% acid treated MWCNTs we observed increase of Young’s modulus from 458 to 723 MPa, tensile strength from 5.29 to 8.83 MPa and fracture strain from 0.16% to 0.25%. For understanding the structure and morphology of nanocomposite, the dispersion states were studied using scanning electron microscopy (SEM) and field emission electron microscopy (FESEM). The results showed better dispersion of modified carbon nanotube than unmodified in polymeric matrix

Thermal and mechanical interfacial properties of epoxy composites based on functionalized carbon nanotubes

International Nuclear Information System (INIS)

Jin Fanlong; Ma Changjie; Park, Soo-Jin

2011-01-01

Highlights: → CNTs were functionalized by acid and amine treatments. → Epoxy resin/CNT composites were prepared. → T g of the composites increased by about 10 deg. C compared to neat epoxy resins. → Toughness of the composites was significantly improved by the addition of functionalized CNTs. - Abstract: Carbon nanotubes (CNTs) were treated by a mixture of acid and functionalized subsequently by amine treatment to improve interfacial interactions and dispersion of CNTs in epoxy matrix. The thermal stabilities and mechanical interfacial properties of epoxy/CNT composites were investigated using several techniques. The dispersion state of CNTs in the epoxy matrix was observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). As a result, the glass transition temperature of epoxy/CNT composites increased by about 11 deg. C compared to neat epoxy resins. The mechanical interfacial property of the composites was significantly increased by the addition of amine treated CNTs. The SEM and TEM results showed that the separation and uniform dispersion of CNTs in the epoxy matrix.

Kevlar 49/Epoxy COPV Aging Evaluation

Science.gov (United States)

Sutter, James K.; Salem, Jonathan L.; Thesken, John C.; Russell, Richard W.; Littell, Justin; Ruggeri, Charles; Leifeste, Mark R.

2008-01-01

NASA initiated an effort to determine if the aging of Kevlar 49/Epoxy composite overwrapped pressure vessels (COPV) affected their performance. This study briefly reviews the history and certification of composite pressure vessels employed on NASA Orbiters. Tests to evaluate overwrap tensile strength changes compared 30 year old samples from Orbiter vessels to new Kevlar/Epoxy pressure vessel materials. Other tests include transverse compression and thermal analyses (glass transition and moduli). Results from these tests do not indicate a noticeable effect due to aging of the overwrap materials.

Fabrication of High Gas Barrier Epoxy Nanocomposites: An Approach Based on Layered Silicate Functionalized by a Compatible and Reactive Modifier of Epoxy-Diamine Adduct

Directory of Open Access Journals (Sweden)

Ran Wei

2018-05-01

Full Text Available To solve the drawbacks of poor dispersion and weak interface in gas barrier nanocomposites, a novel epoxy-diamine adduct (DDA was synthesized by reacting epoxy monomer DGEBA with curing agent D400 to functionalize montmorillonite (MMT, which could provide complete compatibility and reactivity with a DGEBA/D400 epoxy matrix. Thereafter, sodium type montmorillonite (Na-MMT and organic-MMTs functionalized by DDA and polyether amines were incorporated with epoxy to manufacture nanocomposites. The effects of MMT functionalization on the morphology and gas barrier property of nanocomposites were evaluated. The results showed that DDA was successfully synthesized, terminating with epoxy and amine groups. By simulating the small-angle neutron scattering data with a sandwich structure model, the optimal dispersion/exfoliation of MMT was observed in a DDA-MMT/DGEBA nanocomposite with a mean radius of 751 Å, a layer thickness of 30.8 Å, and only two layers in each tactoid. Moreover, the DDA-MMT/DGEBA nanocomposite exhibited the best N2 barrier properties, which were about five times those of neat epoxy. Based on a modified Nielsen model, it was clarified that this excellent gas barrier property was due to the homogeneously dispersed lamellas with almost exfoliated structures. The improved morphology and barrier property confirmed the superiority of the adduct, which provides a general method for developing gas barrier nanocomposites.

Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

International Nuclear Information System (INIS)

Ning, Rong; Chen, Ding; Zhang, Qianxia; Bian, Zhibing; Dai, Haixiong; Zhang, Chi

2014-01-01

Highlights: • TiH 2 was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH 2 with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process

The effect of silanated and impregnated fiber on the tensile strength of E-glass fiber reinforced composite retainer

Directory of Open Access Journals (Sweden)

Niswati Fathmah Rosyida

2015-12-01

Full Text Available Background: Fiber reinforced composite (FRC is can be used in dentistry as an orthodontic retainer. FRC  still has a limitations because of to  a weak bonding between fibers and matrix. Purpose: This research was aimed to evaluate the effect of silane as coupling agent and fiber impregnation on the tensile strength of E-glass FRC. Methods: The samples of this research were classified into two groups each of which consisted of three subgroups, namely the impregnated fiber group (original, 1x addition of silane, 2x addition of silane and the non-impregnated fiber group (original, 1x addition of silane, 2x addition of silane. The tensile strength was measured by a universal testing machine. The averages of the tensile strength in all groups then were compared by using Kruskal Wallis and Mann Whitney post hoc tests. Results: The averages of the tensile strength (MPa in the impregnated fiber group can be known as follow; original impregnated fiber (26.60±0.51, 1x addition of silane (43.38±4.42, and 2x addition of silane (36.22±7.23. The averages of tensile strength (MPa in the non-impregnated fiber group can also be known as follow; original non-impregnated fiber (29.38±1.08, 1x addition of silane (29.38±1.08, 2x addition of silane (12.48±2.37. Kruskal Wallis test showed that there was a significant difference between the impregnated fiber group and the non-impregnated fiber group (p<0.05. Based on the results of post hoc test, it is also known that the addition of silane in the impregnated fiber group had a significant effect on the increasing of the tensile strength of E-glass FRC (p<0.05, while the addition of silane in the non-impregnated fiber group had a significant effect on the decreasing of the tensile strength of E-glass FRC. Conclusion: It can be concluded that the addition of silane in the non-silanated fiber group can increase the tensile strength of E-glass FRC, but the addition of silane in the silanated fiber group can

Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon.

Science.gov (United States)

Choi, Moonjung; Jang, Jyongsik

2008-09-01

Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group of polypyrrole. The introduced polypyrrole layer could provide the surface modification to be applied for heavy metal ion adsorbents. Especially, polymer-impregnated porous carbon has an enhanced heavy metal ion uptake, which is 20 times higher than that of adsorbents with amine functional groups. Furthermore, the relationship between the coated polymer amount and surface area was also investigated in regard to adsorption capacity.

Rhodamine 6G impregnated porous silica: A photoluminescence study

Energy Technology Data Exchange (ETDEWEB)

Anedda, A. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Canada) (Italy); Carbonaro, C.M. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Canada) (Italy)]. E-mail: cm.carbonaro@dsf.unica.it; Clemente, F. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Corpino, R. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Ricci, P.C. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Rossini, S. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy)

2005-12-15

The optical properties of rhodamine 6G dye confined in porous silica are reported. Photoluminescence properties of embedded chromophores in mesoporous hosts can be affected by the surrounding matrices: shifts in emission spectra and variations of photoluminescence quantum yield are found as compared to dye solutions. Host-guest interactions are studied here by varying both SiO{sub 2} xerogels porosity and the dye concentration. Comparing samples obtained by impregnating matrices with 5.4 and 18.2 nm pores with solutions having concentrations in the rhodamine 6G high laser gain, matrices with 5.4 nm pores impregnated with a dye concentration of 5 x 10{sup -4} M are found to be the most stable and efficient in the examined range.

Impregnated Fibrous Materials. Report of a Study Group on Impregnated Fibrous Materials

Energy Technology Data Exchange (ETDEWEB)

NONE

1968-10-15

There has recently been renewed interest in the use of radiation from radioisotopes or particle accelerators to initiate and sustain chemical reactions. Particular attention is being paid to the production of wood-plastic composites, a process which is now a commercial reality with radiation competing against chemical methods to enhance the properties of wood. It has been reported that water repellancy, hardness, weathering, insect and chemical resistance, compressive, bending and shear strength can be significantly improved by the process, but so far there has been a limited commercial outlet for the product. Papers on this subject were presented at the International Atomic Energy Agency's Symposium on Industrial Uses of Large Radiation Sources, Salzburg, May 1963, and since then the Agency has been aware of the interest of developing countries in conducting research on wood and other fibrous materials as a means of further exploiting natural resources. It was felt that some attempt should be made to co-ordinate, on a regional basis, the work being done in this field and at the same time review the world status, including the associated technology in such areas as monomer-polymer chemistry and impregnation techniques where they are directly related to this work. Because of the wide range of fibrous materials being studied there, Asia and the Far East was chosen as the most representative area and 39 participants from 13 countries, and from international organizations, met in Bangkok from 20 to 24 November 1967 to assess the potential of impregnated fibrous materials. This report is a record of the meeting and is based not only on work performed both inside and outside the region but also on details of the resources and industries in the area.

Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties.

Science.gov (United States)

Li, Binghai; Zhang, Xiaohong; Gao, Jianming; Song, Zhihai; Qi, Guicun; Liu, Yiqun; Qiao, Jinliang

2010-09-01

The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.

Epoxy resin/phosphonium ionic liquid/carbon nanofiller systems: Chemorheology and properties

Directory of Open Access Journals (Sweden)

H. Maka

2014-10-01

Full Text Available Epoxy nanocomposites with commercial carbon nanotubes (CNT or graphene (GN have been prepared using phosphonium ionic liquid [trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl phosphinate, IL-f]. IL-f served simultaneously as nanofiller dispersing medium and epoxy resin catalytic curing agent. An influence of IL-f/epoxy weight ratio (3, 6 and 9/100, phr, carbon nanofiller type and content on viscosity of epoxy compositions during storage at ambient temperature was evaluated. Curing process was controlled for neat and CNT or GN modified epoxy compositions (0.25-1.0 wt.% load using differential scanning calorimetry and rheometry. Epoxy nanocomposites exhibited slightly increased glass transition temperature values (146 to 149°C whereas tan δ and storage modulus decreased (0.30 to 0.27 and 2087 to 1070 MPa, respectively as compared to reference material. Crosslink density regularly decreased for composites with increasing CNT content (11 094 to 7 020 mol/m3. Electrical volume resistivity of the nanocomposites was improved in case of CNT to 4•101 Ω•m and GN to 2•105 Ω•m (nanofiller content 1 wt.%. Flame retardancy was found for modified epoxy materials with as low GN and phosphorus content as 0.25 and 0.7 wt.%, respectively (increase of limiting oxygen index to 26.5%.

Comment on the mechanism of operation of the impregnated tungsten cathode

Science.gov (United States)

Forman, R.

1979-01-01

Recent life-test measurements, over 20,000-30,000 h, on impregnated tungsten cathodes in tubes employing an open-type electron-gun structure, show emission current degradation with time. This is in contrast to those recently published by Rittner on B-type cathodes, run in close-spaced diodes, taken some years ago. These more recent life-test results are consistent with the model suggested by Forman and disputed by Rittner that the barium coverage on an impregnated cathode is less than a monolayer for most of its life and decreases with time.

Los cambios de temperatura en los revestimientos epoxi II

Directory of Open Access Journals (Sweden)

Fernández Cánovas, M.

1970-04-01

Full Text Available This article is the second part of a previous paper published by the author in no. 189 of this magazine. It describes the tests carried out to check the theoretical results published in the earlier article. The tests have consisted in submitting concrete slabs covered with a layer of epoxi mortar to certain thermal conditions, to check the behaviour of the covering in the face of thermal changes. In all the tests, described in detail in the article, the epoxi layer has behaved extremely well, and no bonding failure has been observed, nor failures in the concrete base or in the epoxi layer.Este artículo es la segunda parte de un trabajo publicado por el autor en el número 189 de esta revista, y en él se realiza una descripción de los ensayos prácticos llevados a cabo para complementar el estudio teórico publicado en aquella primera parte. Los ensayos han consistido en someter a placas de hormigón revestidas de una Kipa de mor tero epoxi a determinadas condiciones térmicas, con el fin de poder comprobar el comportamiento del revestimiento frente a los cambios de temperatura. En todos los ensayos realizados y que, con detalle, están descritos en este artículo, el comportamiento de los revestimientos de mortero epoxi ha sido excelente, no habiéndose notado ningún fallo de adherencia, ni roturas en la base de hormigón, ni en la capa de mortero epoxi.

A Combined Electro-Thermal Breakdown Model for Oil-Impregnated Paper

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Meng Huang

2017-12-01

Full Text Available The breakdown property of oil-impregnated paper is a key factor for converter transformer design and operation, but it is not well understood. In this paper, breakdown voltages of oil-impregnated paper were measured at different temperatures. The results showed that with the increase of temperature, electrical, electro-thermal and thermal breakdown occurred successively. An electro-thermal breakdown model was proposed based on the heat equilibrium and space charge transport, and negative differential mobility was introduced to the model. It was shown that carrier mobility determined whether it was electrical or thermal breakdown, and the model can effectively explain the temperature-dependent breakdown.

Energy absorption and failure response of silk/epoxy composite square tubes: Experimental

DEFF Research Database (Denmark)

Oshkovr, Simin Ataollahi; Taher, Siavash Talebi; A. Eshkoor, Rahim

2012-01-01

This paper focuses on natural silk/epoxy composite square tubes energy absorption and failure response. The tested specimens were featured by a material combination of different lengths and same numbers of natural silk/epoxy composite layers in form of reinforced woven fabric in thermosetting epoxy...

Incorporation of Hyperbranched Supramolecules into Nafion Ionic Domains via Impregnation and In-Situ Photopolymerization

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Hiruto Kudo

2011-11-01

Full Text Available Nafion membranes were impregnated with photocurable supramolecules, viz., hyperbranched polyester having pendant functional carboxylic acid groups (HBPEAc-COOH by swelling in methanol and subsequently photocured in-situ after drying. Structure-property relationships of the HBPEAc-COOH impregnated Nafion membranes were analyzed on the basis of Fourier transform infrared (FTIR spectroscopy, solid-state nuclear magnetic resonance (SSNMR and dynamic mechanical analysis (DMA. FTIR and SSNMR investigations revealed that about 7 wt % of HBPEAc-COOH was actually incorporated into the ionic domains of Nafion. The FTIR study suggests possible complexation via inter-species hydrogen bonding between the carboxylic groups of HBPEAc-COOH and the sulfonate groups of Nafion. The α-relaxation peak corresponding to the glass transition temperature of the ionic domains of the neat Nafion-acid form was found to increase from ~100 to ~130 °C upon impregnation with enhanced modulus afforded by the cured polyester network within the ionic domains. The AC impedance fuel cell measurement of the impregnated membrane exhibited an increasing trend of proton conductivity with increasing temperature, which eventually surpassed that of neat Nafion above 100 °C. Of particular importance is that the present paper is the first to successfully incorporate polymer molecules/networks into the Nafion ionic domains by means of impregnation with hyperbranched supramolecules followed by in-situ photopolymerization.

Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions

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Milovanović Stoja L.

2016-01-01

Full Text Available The present work was aimed to study swelling kinetics of polylactic acid (PLA and its impregnation with thymol in supercritical carbon dioxide (scCO2 medium. The influences of temperature and soaking time on the swelling kinetics and impregnation yield of PLA cylindrical disc and film were investigated. Swelling experiments were performed in a high pressure view cell at 10 MPa and temperatures of 40°C, 60°C and 75°C for 2 to 24 h. On the basis of swelling kinetics, pressure of 10 MPa and temperature of 40°C were chosen for supercritical solvent impregnation (SSI of the PLA samples during 2 to24 h. The highest swelling extent was observed for the PLA monolith after 24 h treatment with pure scCO2 (7.5% and scCO2 with thymol (118.3%. It was shown that sufficiently high amount of thymol can be loaded into both PLA monolith and film using SSI after only 2 h (10.0% and 6.6%, respectively. Monolith and film of PLA impregnated with thymol could be suitable for active food packaging and sterile medical disposables.

Destruction of Toluene by the Combination of High Frequency Discharge Electrodeless Lamp and Manganese Oxide-Impregnated Granular Activated Carbon Catalyst

Directory of Open Access Journals (Sweden)

Jianhui Xu

2014-01-01

Full Text Available The destruction of low concentration of toluene (0–30 ppm has been studied under the UV/photogenerated O3/MnO2-impregnated granular activated carbon (MnO2-impregnated GAC process by the combination of self-made high frequency discharge electrodeless lamp (HFDEL with MnO2-impregnated GAC catalyst. Experimental results showed that the initial toluene concentration can strongly affect the concentration of photogenerated O3 from HFDEL and the efficiency and mass rate of destruction of toluene via HFDEL/MnO2-impregnated GAC system. Active oxygen and hydroxyl radicals generated from HFDEL/MnO2-impregnated GAC system played a key role in the decomposition of toluene process and the intermediates formed by photolysis are more prone to be mineralized by the subsequent MnO2-impregnated GAC catalyst compared to the original toluene, resulting in synergistic mineralization of toluene by HFDEL/MnO2-impregnated GAC system. The role of MnO2-impregnated GAC catalyst is not only to eliminate the residual O3 completely but also to enhance the decomposition and mineralization of toluene.

Measurements of print-through in graphite fiber epoxy composites

Science.gov (United States)

Jaworske, Donald A.; Jeunnette, Timothy T.; Anzic, Judith M.

1989-01-01

High-reflectance accurate-contour mirrors are needed for solar dynamic space power systems. Graphite fiber epoxy composites are attractive candidates for such applications owing to their high modulus, near-zero coefficient of thermal expansion, and low mass. However, mirrors prepared from graphite fiber epoxy composite substrates often exhibit print-through, a distortion of the surface, which causes a loss in solar specular reflectance. Efforts to develop mirror substrates without print-through distortion require a means of quantifying print-through. Methods have been developed to quantify the degree of print-through in graphite fiber epoxy composite specimens using surface profilometry.

Flexural properties of treated and untreated kenaf/epoxy composites

International Nuclear Information System (INIS)

Yousif, B.F.; Shalwan, A.; Chin, C.W.; Ming, K.C.

2012-01-01

Graphical abstract: Untreated kenaf fibre/epoxy composites. Treated kenaf fibre/epoxy composites. Highlights: ► Treatment of kenaf fibres with 6% NaOH has improved the flexural properties of epoxy composites. ► Interfacial adhesion of the natural fibres is controlled by the microstructure of the fibres. ► Kenaf fibres have a potential to replace glass fibres for flexural applications. -- Abstract: In the current work, flexural properties of unidirectional long kenaf fibre reinforced epoxy (KFRE) composites are studied. The kenaf fibres were prepared into two types as untreated and treated (with 6% NaOH). The failure mechanism and damage features of the materials were categorized with the surface observation by scanning electron microscope (SEM). The results revealed that reinforcement of epoxy with treated kenaf fibres increased the flexural strength of the composite by about 36%, while, untreated fibres introduced 20% improvement. This was mainly due to the high improvement of the chemical treatment (NaOH) on the interfacial adhesion of the fibres and the porosity of the composites which prevented the debonding, detachments or pull out of fibres. For untreated KFRE, the fracture mechanisms were debonding, tearing, detachments and pull out of fibres. The developed composite exhibited superior properties compared to the previous composites based on natural and synthetic fibres.

Characterization of epoxy hybrid composites filled with cellulose fibers and nano-SiC

KAUST Repository

Alamri, H.

2012-04-06

Three different approaches have been applied and investigated to enhance the thermal and mechanical properties of epoxy resin. Epoxy system reinforced with either recycled cellulose fibers (RCF) or nanosilicon carbide (n-SiC) particles as well as with both RCF and n-SiC has been fabricated and investigated. The effect of RCF/n-SiC dispersion on the mechanical and thermal properties of these composites has been characterized. The fracture surface morphology and toughness mechanisms were investigated by scanning electron microscopy. The dispersion of n-SiC particles into epoxy nanocomposites was studied by synchrotron radiation diffraction and transmission electron microscopy. Results indicated that mechanical properties increased as a result of the addition of n-SiC. The presence of RCF layers significantly increased the mechanical properties of RCF/epoxy composites when compared with neat epoxy and its nanocomposites. The influence of the addition of n-SiC to RCF/epoxy composites in mechanical properties was found to be positive in toughness properties. At high temperatures, thermal stability of neat epoxy increased due to the presence of either n-SiC particles or RCF layers. However, the presence of RCF accelerated the thermal degradation of neat epoxy as well as the addition of n-SiC to RCF/epoxy samples increased the rate of the major thermal degradation. © 2012 Wiley Periodicals, Inc.

ORGANIC/INORGANIC HYBRID EPOXY NANOCOMPOSITES BASED ON OCTA(AMINOPHENYL)SILSESQUIOXANE

Institute of Scientific and Technical Information of China (English)

Hai-bo Fan; Rong-jie Yang; Xiang-mei Li

2013-01-01

Octa(aminophenyl)silsesquioxane (OAPS) was used as the curing agent of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin.A study on comparison of DGEBA/OAPS with DGEBA/4,4'-diaminodiphenyl sulfone (DDS) epoxy resins was achieved.Differential scanning calorimetry was used to investigate the curing reaction and its kinetics,and the glass transition of DGEBA/OAPS.Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins.The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy.Scanning electron microscopy was used to observe morphology of the two epoxy resins.The results indicated that OAPS had very good compatibility with DGEBA in molecular level,and could form a transparent DGEBA/OAPS resin.The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS.The DGEBA/OAPS resin didn't exhibit glass transition,but the DGEBA/DDS did,which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points.Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin.Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield,but its initial decomposition temperature seemed to be lowered.

Exit Presentation: Infrared Thermography on Graphite/Epoxy

Science.gov (United States)

Comeaux, Kayla

2010-01-01

This slide presentation reports on the internship project that was accomplished during the summer of 2010. The objectives of the project were to: (1) Simulate Flash Thermography on Graphite/Epoxy Flat Bottom hole Specimen and thin void specimens, (2) Obtain Flash Thermography data on Graphite/Epoxy flat bottom hole specimens, (3) Compare experimental results with simulation results, Compare Flat Bottom Hole Simulation with Thin Void Simulation to create a graph to determine size of IR Thermography detected defects

Mechanical and Magnetic Properties of YBCO Superconductor with Bi/CNT Composite and Resin/CNT Impregnation

International Nuclear Information System (INIS)

Oh, W. S.; Jang, G. E.; Han, Y. H.; Sung, T. H.

2007-01-01

Bi/CNT composite and resin/CNT were chosen to improve the mechanical properties of YBa 2 Cu 3 O 7 (YBCO) superconductor. In order to elucidate the effects of Bi/CNT composite and resin/CNT in YBCO superconductors, melt texture superconductor were impregnated by mixed compound of Bi and CNT into the artificial holes parallel to the c-axis, which were drilled on the YBCO superconductor. Various amount of Bi/CNT and resin/CNT were impregnated to YBCO superconductor with different holes diameters. Typical artificial holes diameters were 0.5, 0.7, and 1.0 mm respectively. Result of three-point bending test measurement, the bending strength with resin/CNT impregnation was improved up to 59.64 MPa as compared with 50.79 MPa of resin/CNT free bulk. Resin/CNT impregnation has been found to be one of the effective ways in improving the mechanical properties of bulk superconductor.

Realtime 3D stress measurement in curing epoxy packaging

DEFF Research Database (Denmark)

Richter, Jacob; Hyldgård, A.; Birkelund, Karen

2007-01-01

This paper presents a novel method to characterize stress in microsystem packaging. A circular p-type piezoresistor is implemented on a (001) silicon chip. We use the circular stress sensor to determine the packaging induced stress in a polystyrene tube filled with epoxy. The epoxy curing process...

Thermoset precursor

International Nuclear Information System (INIS)

Yamamoto, Y.

1983-04-01

This invention pertains to a distinctive thermoset precursor which is prepared by mixing a resin composition (A) which can be hardened by ionizing radiation, and a resin composition (B) which can be hardened by heat but cannot be hardened by, or is resistant to, ionizing radiation, and by coating or impregnating a molding or other substrate with a sheet or film of this mixture and irradiating this with an ionizing radiation. The principal components of composition (A) and (B) can be the following: (1) an acrylate or methacrylate and an epoxy resin and an epoxy resin hardener; (2) an unsaturated polyester resin and epoxy resin and an epoxy resin hardener; (3) a diacrylate or dimethacrylate or polyethylene glycol and an epoxy resin; (4) an epoxy acrylates or epoxy methacrylate obtained by the addition reaction of epoxy resin and acrylic or methacrylic acid

Effects of ultraviolet and electron radiations on graphite-reinforced polysulfone and epoxy resins

International Nuclear Information System (INIS)

Giori, C.; Yamauchi, T.

1984-01-01

Degradation mechanisms have been investigated for graphite/polysulfone and graphite/epoxy laminates exposed to ultraviolet and high-energy electron radiations in vacuum up to 960 equivalent sun hours and 10 9 rads, respectively. Based on GC and combined GC/MS analysis of volatile by-products evolved during irradiation, several free radical mechanisms of composite degradation have been identified. All the composite materials evaluated have shown high electron radiation stability and relatively low ultraviolet stability as indicated by low G values and high quantum yields for gas formation. Mechanical property measurements of irradiated samples did not reveal significant changes, with the possible exception of UV exposed polysulfone laminates. Hydrogen and methane have been identified as the main byproducts of irradiation, along with unexpectedly high levels of CO and CO 2 . Initial G values for methane relative to hydrogen formation are higher in the presence of isopropylidene linkages, which occur in bisphenol-A resins

Enhanced Flexural Strength of Tellurium Nanowires/epoxy Composites with the Reinforcement Effect of Nanowires

Science.gov (United States)

Balguri, Praveen Kumar; Harris Samuel, D. G.; Aditya, D. B.; Vijaya Bhaskar, S.; Thumu, Udayabhaskararao

2018-02-01

Investigating the mechanical properties of polymer nanocomposite materials has been greatly increased in the last decade. In particular, flexural strength plays a major role in resisting bending and shear loads of a composite material. Here, one dimensional (1D) tellurium nanowires (TeNWs) reinforced epoxy composites have been prepared and the flexural properties of resulted TeNWs/epoxy nanocomposites are studied. The diameter and length of the TeNWs used to make TeNWs/epoxy nanocomposites are 21±2.5 nm and 697±87 nm, respectively. Plain and TeNWs/epoxy nanocomposites are characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Furthermore, significant enhancement in the flexural strength of TeNWs/epoxy nanocomposite is observed in comparison to plain epoxy composite, i.e. flexural strength is increased by 65% with the addition of very little amount of TeNWs content (0.05 wt.%) to epoxy polymer. Structural details of plain and TeNWs/epoxy at micrometer scale were examined by scanning electron microscopy (SEM). We believe that our results provide a new type of semiconductor nanowires based high strength epoxy polymer nanocomposites.

Textile impregnation with thermoplastic resin - models and application

NARCIS (Netherlands)

Loendersloot, Richard; Grouve, Wouter Johannes Bernardus; Lamers, E.A.D.; Wijskamp, Sebastiaan; Kelly, P.A.; Bickerton, S.; Lescher, P.; Govignon, Q.

2012-01-01

One of the key issues of the development of cost-effective thermoplastic composites for the aerospace industry is the process quality control. A complete, void free impregnation of the textile reinforcement by the thermoplastic resin is an important measure of the quality of composites. The

Behaviour of Epoxy Silica Nanocomposites Under Static and Creep Loading

Science.gov (United States)

Constantinescu, Dan Mihai; Picu, Radu Catalin; Sandu, Marin; Apostol, Dragos Alexandru; Sandu, Adriana; Baciu, Florin

2017-12-01

Specific manufacturing technologies were applied for the fabrication of epoxy-based nanocomposites with silica nanoparticles. For dispersing the fillers in the epoxy resin special equipment such as a shear mixer and a high energy sonicator with temperature control were used. Both functionalized and unfunctionalized silica nanoparticles were added in three epoxy resins. The considered filling fraction was in most cases 0.1, 0.3 and 0.5 wt%.. The obtained nanocomposites were subjected to monotonic uniaxial and creep loading at room temperature. The static mechanical properties were not significantly improved regardless the filler percentage and type of epoxy resin. Under creep loading, by increasing the stress level, the nanocomposite with 0.1 wt% silica creeps less than all other materials. Also the creep rate is reduced by adding silica nanofillers.

Pore structure, mechanical properties and polymer characteristics of porous materials impregnated with methylmethacrylate

International Nuclear Information System (INIS)

Hastrup, K.

1976-05-01

The pore structure of porous materials plays a decisive role with regard to many properties of the materials. One therefore expects property improvement due to impregnation to be mostly brought about as a result of pore structure modification. This supposition formed the basis for the project here presented, which had the main aim of investigating polymer impregnation in relation to pore structure. Objectives were: 1) to examine the pore structure of hardened cement paste, beech wood and porous glass before and after gas-phase impregnation with methyl-methacrylate monomer and in situ polymerization, 2) to investigate the influence of the pore structure on the molecular weight of the polymer, 3) to investigate the influence of the degree of pore filling on the elastic modulus, damping coefficient and bending strength. (author)

The Effects of Natural Weathering on Color Stability of Impregnated and Varnished Wood Materials

Directory of Open Access Journals (Sweden)

Turkay Turkoglu

2015-01-01

Full Text Available The aim of this study was to investigate effects of natural weathering on color stability of Scots pine (Pinus sylvestris L. and Oriental beech (Fagus orientalis L. impregnated with some chemicals [tanalith-E (TN-E, adolit-KD5 (AD-KD5, and chromated copper arsenate (CCA] and then varnished [synthetic varnish (SV and polyurethane varnish (PV]. While applying varnish increased lightness, impregnation decreased lightness of the wood specimens before natural weathering. Natural weathering caused greenish, bluish, and dark color tones of the wood surface. Total color change was increased with increasing exposure times in natural weathering. Untreated (control wood specimens exhibited higher color changes than the other wood specimens in all the stages of natural weathering. The total color changes of untreated Oriental beech specimens were less than untreated Scots pine specimens. The color stability of impregnated and varnished wood specimens gave better results than untreated and solely varnished wood specimens after natural weathering. The best color stability was obtained from both Oriental beech and Scots pine wood impregnated with TN-E before PV coating.

Synthesis and characterization of polyimide-epoxy hybrid films

International Nuclear Information System (INIS)

Butt, M.S.; Akhter, Z.; Siddiqi, H.M.

2011-01-01

Composites from polyimide and epoxy-amine were prepared aiming for enhancing its thermal and mechanical properties. Polyimide-epoxy-amine hybrid films were prepared by blending of polyimide and epoxy-amine in different ratios whereas, polyimide was prepared by reacting 1,2-di(p-aminophenyloxy)ethylene with 3,3/sub '/4,4/sub '/-benzophenone tetracarboxylic acid dianhydride. The blend systems with Araldite LY564 (1,4-butanediolediglycidyl ether) (BDDE) and Hardener HY2954 (3,3/sub '/-dimethyl-4,4/sub '/-diamino dicyclohexyl)methane (MACM) were investigated in term of thermal, mechanical and viscoelastic measurements. Thermal stability was determined using thermogravimetric analysis. The effect of the polyimide content on the glass transition temperature (Tg) and thermal stability was observed. Viscoelastic measurements showed that the glass transition temperature shifted with the increase of polyimide content. The composites showed higher thermal stability in comparison with neat epoxy-amine matrix for higher polyimide concentration. The effect of polyimide content on the mechanical properties was also investigated. The tensile measurements of the films showed that with the increase of polyimide content the tensile modulus of the films was increased. (author)

Characterization of Hybrid Epoxy Nanocomposites

Science.gov (United States)

Simcha, Shelly; Dotan, Ana; Kenig, Samuel; Dodiuk, Hanna

2012-01-01

This study focused on the effect of Multi Wall Carbon Nanotubes (MWCNT) content and its surface treatment on thermo-mechanical properties of epoxy nanocomposites. MWCNTs were surface treated and incorporated into two epoxy systems. MWCNT's surface treatments were based on: (a) Titania coating obtained by sol-gel process and (b) a nonionic surfactant. Thermo-mechanical properties improvement was obtained following incorporation of treated MWCNT. It was noticed that small amounts of titania coated MWCNT (0.05 wt %) led to an increase in the glass transition temperature and stiffness. The best performance was achieved adding 0.3 wt % titania coated MWCNT where an increase of 10 °C in the glass transition temperature and 30% in storage modulus were obtained. PMID:28348313

Combustion Characteristics of Impregnated and Surface-treated Chestnut (Castanea sativa Mill. Wood Left Outdoors for One Year

Directory of Open Access Journals (Sweden)

Muhammed Said Fidan

2016-01-01

Full Text Available Treating wood with impregnating materials in order to improve resistance to burning is a commonly employed safety measure. In this study, chestnut (Castanea sativa Mill. wood samples were impregnated using either Tanalith-E or Wolmanit-CB according to ASTM-D 1413-76 and surface-treated using water-based or synthetic varnish according to ASTM-D 3023. These samples were used to investigate the combustion characteristics of samples left outdoors for one year as detailed in ASTM-E 160-50. The combustion temperatures of the samples left outdoors were similar upon impregnation with either Tanalith-E or Wolmanit-CB. However, the combustion temperature of the samples treated with synthetic varnish was lower than those that were treated with water-based varnish. The time to collapse and the total duration of combustion of the samples left outdoors were shorter for those impregnated with Wolmanit-CB. Weight loss of the samples left outdoors was higher for those that were impregnated with Tanalith-E and treated with water-based varnish. Gas analysis of the samples that were left outdoors indicated that the O2 content of flue gas from samples that were impregnated with Wolmanit-CB and treated with synthetic varnish was high and the CO content of flue gas from the same samples was low.

Conservation experiments applying radiation-curable impregnating agents to intact and artifically decayed wood samples

International Nuclear Information System (INIS)

Schaudy, R.; Slais, E.

1983-02-01

Conservation experiments have been performed applying 10 selected impregnating agents to intact and chemically as well as biologically decayed wood samples. The quality of the radiation-curable impregnating agents could be valued by determination of the monomer uptake, the alteration of dimensions and volume and the deformation of the samples. The results are to be discussed. (Author) [de

Thermal properties and corrosion resistance of organoclay/epoxy resin film

Science.gov (United States)

Baiquni, M.; Soegijono, B.

2018-03-01

Hybrid materials organoclay/epoxy resin films were prepared by varying organoclay content in epoxy resin as a matrix. The film were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermal conductivity. TGA and FT-IR results confirmed that the melting temperature shifted to a lower point. The thermal conductivity and corrosion resistant generally increase with increasing organoclay content. The changes on these properties may due to cross link between organoclay and epoxy.

Preparation and Various Characteristics of Epoxy/Alumina Nanocomposites

Science.gov (United States)

Kozako, Masahiro; Ohki, Yoshimichi; Kohtoh, Masanori; Okabe, Shigemitsu; Tanaka, Toshikatsu

Epoxy/ alumina nanocomposites were newly prepared by dispersing 3, 5, 7, and 10 weight (wt) % boehmite alumina nanofillers in a bisphenol-A epoxy resin using a special two-stage direct mixing method. It was confirmed by scanning electron microscopy imaging that the nanofillers were homogeneously dispersed in the epoxy matrix. Dielectric, mechanical, and thermal properties were investigated. It was elucidated that nanofillers affects various characteristics of epoxy resins, when they are nanostructrued. Such nano-effects we obtained are summarized as follows. Partial discharge resistance increases as the filler content increases; e.g. 7 wt% nanofiller content creates a 60 % decrease in depth of PD-caused erosion. Weibull analysis shows that short-time electrical treeing breakdown time is prolonged to 265 % by 5 wt% addition of nanofillers. But there was more data scatter in nanocomposites than in pure epoxy. Permittivity tends to increase from 3.7 to 4.0 by 5 wt% nanofiller addition as opposed to what was newly found in the recent past. Glass transition temperature remains unchanged as 109 °C. Mechanical properties such as flexural strength and flexural modulus increase; e.g. flexural strength and flexural modulus are improved by 5 % and 8 % with 5 wt% content, respectively. Excess addition causes a reverse effect. It is concluded from permittivity and glass transition temperature characteristics that interfacial bonding seems to be more or less weak in the nanocomposite specimens prepared this time, even though mechanical strengths increase. There is a possibility that the nanocomposites specimens will be improved in interfacial quality.

Liquid crystalline epoxy nanocomposite material for dental application.

Science.gov (United States)

Tai, Yun-Yuan; Hsu, Sheng-Hao; Chen, Rung-Shu; Su, Wei-Fang; Chen, Min-Huey

2015-01-01

Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment. Copyright © 2014. Published by Elsevier B.V.

The effects of MWNT on thermal conductivity and thermal mechanical properties of epoxy

Science.gov (United States)

Ismadi, A. I.; Othman, R. N.

2017-12-01

Multiwall nanotube (MWNT) was used as filler in various studies to improve thermal conductivity and mechanical properties of epoxy. Present study varied different weight loading (0, 0.1 %, 0.5 %, 1 %, 1.5 %, 3 % and 5 %) of MWNT in order to observe the effects on the epoxy. Nanocomposite was analyzed by dynamic-mechanical thermal analyser (DMTA) and KD2 pro analyzer. DMTA measured storage modulus (E') and glass transition temperature (Tg) of the nanocomposite. Result showed that Tg value of neat epoxy is higher than all MWNT epoxy nanocomposite. Tg values drop from 81.55 °C (neat epoxy) to 65.03 °C (at 0.1 wt%). This may happen due to the agglomeration of MWNT in the epoxy. However, Tg values increases with the increase of MWNT wt%. Tg values increased from 65.03 °C to 78.53 °C at 1 wt%. Increment of storage modulus (E') at 3 °C (glassy region) was observed as the MWNT loading increases. Maximum value of E' during glassy region was observed to be at 5 wt% with (7.26±0.7) E+08 Pa compared to neat epoxy. On the contrary, there is slight increased and slight decreased with E' values at 100 °C (rubbery region) for all nanocomposite. Since epoxy exhibits low thermal conductivity properties, addition of MWNT has enhanced the properties. Optimum value of thermal conductivity was observed at 3 wt%. The values increased up to 9.03 % compared to neat epoxy. As expected, the result showed decrease value in thermal conductivity at 5 wt% as a result of agglomeration of MWNT in the epoxy.

In situ measurement using FBGs of process-induced strains during curing of thick glass/epoxy laminate plate

DEFF Research Database (Denmark)

Nielsen, Michael Wenani; Schmidt, Jacob Wittrup; Hattel, Jesper Henri

2012-01-01

For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in-service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process-induced shape distortions and residual stresses. In this paper, embedded fibre...... Bragg grating sensors are used to monitor process-induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary...... conditions are employed. The accuracy of the CHILE model in predicting process-induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model...

High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

Science.gov (United States)

Keeratitham, Waralee; Somwangthanaroj, Anongnat

2016-03-01

Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (Tg) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that Tg obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (˜90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

Non-isothermal cure and exfoliation of tri-functional epoxy-clay nanocomposites

Directory of Open Access Journals (Sweden)

F. Shiravand

2015-08-01

Full Text Available The non-isothermal cure kinetics of polymer silicate layered nanocomposites based on a tri-functional epoxy resin has been investigated by differential scanning calorimetry. From an analysis of the kinetics as a function of the clay content, it can be concluded that the non-isothermal cure reaction can be considered to consist of four different processes: the reaction of epoxy groups with the diamine curing agent; an intra-gallery homopolymerisation reaction which occurs concurrently with the epoxy-amine reaction; and two extra-gallery homopolymerisation reactions, catalysed by the onium ion of the organically modified clay and by the tertiary amines resulting from the epoxy-amine reaction. The final nanostructure displays a similar quality of exfoliation as that observed for the isothermal cure of the same nanocomposite system. This implies that the intra-gallery reaction, which is responsible for the exfoliation, is not significantly inhibited by the extra-gallery epoxy-amine cross-linking reaction.

Tensile properties of compressed moulded Napier/glass fibre reinforced epoxy composites

Science.gov (United States)

Fatinah, T. S.; Majid, M. S. Abdul; Ridzuan, M. J. M.; Hong, T. W.; Amin, N. A. M.; Afendi, M.

2017-10-01

This paper describes the experimental investigation of the tensile properties of compressed moulded Napier grass fibres reinforced epoxy composites. The effect of treatment 5% sodium hydroxide (NaOH) concentrated solution and hybridization of Napier with CSM E-glass fibres on tensile properties was also studied. The untreated and treated Napier fibres with 25% fibre loading were fabricated with epoxy resin by a cold press process. 7% fibre loading of CSM glass fibre was hybrid as the skin layer for 18% fibre loading of untreated Napier grass fibre. The tensile tests were conducted using Universal Testing Machine in accordance with ASTM D638. The tensile properties of the untreated Napier/epoxy composites were compared with treated Napier/epoxy and untreated Napier/CSM/epoxy composites. The results demonstrated that the tensile performance of untreated Napier fibre composites was significantly improved by both of the modification; alkali treatment and glass fibre hybridization. Napier grass fibres showed promising potentials to be used as reinforcement in the polymer based composites.

Plant Oil-Derived Epoxy Polymers toward Sustainable Biobased Thermosets.

Science.gov (United States)

Wang, Zhongkai; Yuan, Liang; Ganewatta, Mitra S; Lamm, Meghan E; Rahman, Md Anisur; Wang, Jifu; Liu, Shengquan; Tang, Chuanbing

2017-06-01

Epoxy polymers (EPs) derived from soybean oil with varied chemical structures are synthesized. These polymers are then cured with anhydrides to yield soybean-oil-derived epoxy thermosets. The curing kinetic, thermal, and mechanical properties are well characterized. Due to the high epoxide functionality per epoxy polymer chain, these thermosets exhibit tensile strength over an order of magnitude higher than a control formulation with epoxidized soybean oil. More importantly, thermosetting materials ranging from soft elastomers to tough thermosets can be obtained simply by using different EPs and/or by controlling feed ratios of EPs to anhydrides. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical changes and tensile and electrical properties of epoxy ...

African Journals Online (AJOL)

The properties of epoxy rsesin can be improved by the use of nanofiller such as carbon black (CB), The nanocomposite was synthesized by dispersion via sonication and shear mixing. The morphology, surface chemistry and the structure of CB and the epoxy/CB nanocomposites were investigated using XPS, FTIR, FESEM, ...

Education and Public Outreach for NASA's EPOXI Mission.

Science.gov (United States)

McFadden, Lucy-Ann A.; Crow, C. A.; Behne, J.; Brown, R. N.; Counley, J.; Livengood, T. A.; Ristvey, J. D.; Warner, E. M.

2009-09-01

NASA's EPOXI mission is reusing the Deep Impact (DI) flyby spacecraft to study comets and extra-solar planets around other stars. During the Extrasolar Planetary Observations and Characterization (EPOCh) phase of the mission extrasolar planets transiting their parent stars were observed to gain further knowledge and understanding of planetary systems. Observations of Earth also allowed for characterization of Earth as an extrasolar planet. A movie of a lunar transit of the Earth created from EPOCh images and links to existing planet finding activities from other NASA missions are available on the EPOXI website. The Deep Impact Extended Investigation (DIXI) continues the Deep Impact theme of investigating comet properties and formation by observing comet Hartley 2 in November 2010. The EPOXI Education and Public Outreach (E/PO) program is both creating new materials and updating and modifying existing Deep Impact materials based on DI mission results. Comparing Comets is a new educational activity under development that will guide students in conducting analyses of comet surface features similar to those the DIXI scientists will perform after observing comet Hartley 2. A new story designed to stimulate student creativity was developed in alignment with national educational standards. EPOXI E/PO also funded Family Science Night (FSN), a program bringing together students, families, and educators for an evening at the National Air and Space Museum in Washington, DC. FSN events include time for families to explore the museum, a presentation by a space scientist, and an astronomy themed IMAX film. Nine events were held during the 2008-2009 school year with a total attendance of 3,145 (attendance since inception reached 44,732). Half of attendance is reserved for schools with high percentages of underrepresented minorities. EPOXI additionally offers a bi-monthly newsletter to keep the public, teachers, and space enthusiasts updated on current mission activities. For more

Conservation of waterlogged wood by freeze-drying and optional resin impregnation

International Nuclear Information System (INIS)

Schaudy, R.

1987-09-01

As a contribution to the 'International Comparative Study on Waterlogged Wood' (Grattan-Schweingruber-Project) of the ICOM Working Group on Waterlogged Organic Materials seven archaeological wood samples from sites in Canada, England, the Netherlands, Japan, Norway and Western Australia have been treated. The conservation process consisted of freeze-drying following a polyethylene glycol (PEG 400) treatment and - for fragile objects - of a resin impregnation using a radiation-curable impregnant and gamma radiation for curing. The results are discussed, however without paying regard to the other contributions to this international study. 20 refs., 3 tabs., 30 figs. (Author)

Vacuum mechatronics

Science.gov (United States)

Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

1989-01-01

The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

Aging in CTBN modified epoxy resin stocks

International Nuclear Information System (INIS)

Creed, K.E. Jr.

1979-01-01

The cause of degradation in the glass transition temperature (T/sub G/) of a partially crystallized polymer was investigated. Sample epoxy resin filled capacitors were cured at 90 0 C for 24 hours, then stored at room atmospheric conditions. These showed typical degradation in T/sub G/ after storage for one month. One set of epoxy resin castings was stored at room atmosphere and another set was stored in a dry box at 0% relative humidity and 27 0 C. The samples at room atmospheric conditions showed typical degradation in T/sub G/, while the T/sub G/ for those stored in the dry box increased. Further tests were then made on epoxy resin castings at various curing temperatures and times at both room atmosphere and 0% humidity. Resulting data indicated that absorption of moisture during storage was the predominant cause of T/sub G/ degradation, with stress relaxation another, though smaller, contributing factor

Spall Strength Measurements in Transparent Epoxy Polymers

Science.gov (United States)

Pepper, Jonathan; Rahmat, Meysam; Petel, Oren

2017-06-01

Polymer nanocomposites are seeing more frequent use in transparent armour applications. The role of the microstructure on the performance of these materials under dynamic tensile loading conditions is of particular interest. In the present study, a series of plate impact experiments was conducted in order to evaluate the dynamic response of an epoxy (EPON 828) cured with two differed hardeners. The purpose was to compare the role of these hardeners on the dynamic performance of the resulting transparent epoxy. The material response was resolved with a multi-channel photonic Doppler velocimeter. This system was used to determine the shock Hugoniot and dynamic tensile (spall) strength of the materials. The experimental results are presented in reference to spall theory and are evaluated against results predicted by an analytical model of the impacts. While varying the hardener did not change the shock Hugoniot of the epoxy, it did have an effect on the measured spall strengths.

Epoxy-silicate nanocomposites: Cure monitoring and characterization

International Nuclear Information System (INIS)

Hussain, Farzana; Chen, Jihua; Hojjati, Mehdi

2007-01-01

Epoxy-clay nanocomposites were prepared with organically modified layered clay with varying clay contents (1-8 wt.%). Neat resin and nanocomposite were characterized using different techniques. At first, the effect of nanoclay concentration on the cure behaviour was investigated using an on-line dielectric cure monitoring technique. Differential scanning calorimetry (DSC) was used to verify the dielectric measurement results. Furthermore, mechanical and thermal properties were studied using tensile test and Dynamic Mechanical Analysis (DMA), respectively. Experimental results showed that properties of the epoxy were changed evidently because of the nanoclay loading. The tensile modulus of the nanocomposites increased by 47%, however, no improvement in tensile strength and glass transition temperature (T g ) was observed. Fracture surface of the tensile samples were analyzed by Scanning Electron Microscope (SEM). The nanocomposites structures were characterized with Wide Angle X-Ray Diffraction (WAXD) and Transmission Electron Microscopy (TEM), which revealed the intercalated morphology of clay layers in the epoxy resin systems

Radiation curing of γ-Al2O3 filled epoxy resin

International Nuclear Information System (INIS)

Kang, Phil Hyun; Kim, Dong Jin; Nho, Young Chang

2003-01-01

Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications but characterized by a relatively low toughness. Recently, the incorporation with rigid inorganic was suggested to improve the mechanical properties of epoxy resins. In the present work, an attempt has been taken to disperse nano-sized γ- Al 2 O 3 particles into diglycidyl ether of bisphenol-A (DGEBA) epoxy resins for improvement of the mechanical properties. These hybrid epoxy-alumina composites were prepared using by the γ-ray curing technique that was conducted with 100kGy under nitrogen at room temperature. The composites were characterized by determining gel content, UTM (Instron model 4443), SEM, FT-IR studies

Preparations and applications in UV curing coatings of epoxy acrylates containing carboxyl

International Nuclear Information System (INIS)

Wu Yu Min

1999-01-01

This paper introduces preparations of epoxy acrylates containing carboxyl through the reactions of epoxy acrylates with butanedioic anhydride, pentanedioic anhydride, cis-butenedioic anhydride, phthalic anhydride, tetrabromophthalic anhydride and -tetrahydrophthalic anhydride. These epoxy acrylates containing carboxyl have been applied to UV-curing coatings and their effects on properties of UV-curing coatings have been studied

Supercritical impregnation of cinnamaldehyde into polylactic acid as a route to develop antibacterial food packaging materials.

Science.gov (United States)

Villegas, Carolina; Torres, Alejandra; Rios, Mauricio; Rojas, Adrián; Romero, Julio; de Dicastillo, Carol López; Valenzuela, Ximena; Galotto, María José; Guarda, Abel

2017-09-01

Supercritical impregnation was used to incorporate a natural compound with antibacterial activity into biopolymer-based films to develop active food packaging materials. Impregnation tests were carried out under two pressure conditions (9 and 12MPa), and three depressurization rates (0.1, 1 and 10MPamin -1 ) in a high-pressure cell at a constant temperature equal to 40°C. Cinnamaldehyde (Ci), a natural compound with proven antimicrobial activity, was successfully incorporated into poly(lactic acid) films (PLA) using supercritical carbon dioxide (scCO 2 ), with impregnation yields ranging from 8 to 13% w/w. Higher pressure and slower depressurization rate seem to favor the Ci impregnation. The incorporation of Ci improved thermal, structural and mechanical properties of the PLA films. Impregnated films were more flexible, less brittle and more resistant materials than neat PLA films. The tested samples showed strong antibacterial activity against the selected microorganisms. In summary, this study provides an innovative route to the development of antibacterial biodegradable materials, which could be used in a wide range of applications of active food packaging. Copyright © 2017 Elsevier Ltd. All rights reserved.

ANALISIS ARAH DAN PERLAKUAN SERAT TAPIS SERTA RASIO EPOXY HARDENER TERHADAP SIFAT FISIS DAN MEKANIS KOMPOSIT TAPIS/EPOXY

Directory of Open Access Journals (Sweden)

Putu Lokantara

2012-11-01

Full Text Available Tapis kelapa (Coconut filter as natural fiber, in this time its resources very copius but no longer be exploited and thrown off hand as waste though in fact its used for other material dissimilar inovatif and high economic valuable that is as one of natural fiber alternative to be composite. The objective of this research is to investigate the behavior changing of physical and mechanical properties of composite tapis kelapa as reinforcement and epoxy 7120 with hardener Versamid 140 as matrix. The fiber is treated with the chemical NaOH and KMnO4 with percentage 0.5%, 1%, and 2% in weight, respectively. The ratio of epoxy and hardener is 7:3 and 6:4, and fiber orientation 0o, 45o, dan 90o. For testing of the speciment in tensile test with ASTM standard D3039 and three point bending test with ASTM standard D790. The result of this research obtained that fiber treatment with KMnO4 give the better effect to machine properties compared to NaOH. Variation of percentage 0.5%, 1%, and 2% NaOH and KMnO4 give the effect in fiber surface which higher percentage make the cleaner of surface, decrease of wax contain, and roughness of fiber surface so that stronger of linkage of fiber and matrix and increase of tensile strength, bending strength, and bending modulus of the composite. The highest tensile strength, modulus of elasticity and bending strength are 70.23 MPa, 446.24 GPa and 97.81 MPa respectively reached at composite with ratio epoxy/hardener 7:3; by 2% KMnO4 and fiber orientation 45o. While the highest modulus of elasticity is 385.48 GPa reached at composite with the ratio epoxy/hardener 6:4; 2% KMnO4 and fiber orientation 90o. Keywords: Tensile Strength, bending strength, ratio of epoxy/hardener, NaOH, KMnO4

Epoxy-resin adhesive and method for bonding using such an epoxy resin adhesive

NARCIS (Netherlands)

Bhowmik, S.; Poulis, J.A.; Benedictus, R.

2008-01-01

The invention relates to an epoxy resin adhesive comprising a dotation of nano-substances, wherein the nano- substances are selected from the group comprising carbon-fibre nanotubes, carbon nano-fibres, silicate nano powders, and wherein the nano-substances are dispersed in the adhesive with a

Forecasting the condition of petroleum impregnated load bearing ...

African Journals Online (AJOL)

Petroleum products (PP) used in industrial processes systematically fall on the load-bearing CRC structures and gradually impregnate therein. Currently, available guidelines for the assessment of technical condition and reliability of load-bearing CRC structures do not fully take into account the effect of viscosity of PP that ...

Preparation and Properties of Epoxy Resin-Coated Micro-Sized Ferrosilicon Powder

OpenAIRE

Ku,Jiangang; Chen,Huihuang; He,Kui; Yan,Quanxiang

2016-01-01

Ferrosilicon powder surface coated with a dense epoxy resin membrane was prepared via coating precipitation methods using silane coupling agents as the modifier and epoxy resin as the coating agent. FTIR, FESEM, MPMS-XL, and TG-DSC were used to analyze the morphology, surface composition, magnetic property and thermostability of ferrosilicon powder before and after the modification and coating. The experimental results indicate that epoxy resin membranes of a certain thickness were successful...

A built-in sensor with carbon nanotubes coated by Ag clusters for deformation monitoring of glass fibre/epoxy composites

Science.gov (United States)

Slobodian, P.; Riha, P.; Matyas, J.; Olejnik, R.; Lloret Pertegás, S.; Schledjewski, R.; Kovar, M.

2018-03-01

A multiwalled carbon nanotube network embedded in a polyurethane membrane was integrated into a glass fibre reinforced epoxy composite by means of vacuum infusion to become a part of the composite and has been serving for a strain self-sensing functionality. Besides the pristine nanotubes also nanotubes with Ag nanoparticles attached to their surfaces were used to increase strain sensing. Moreover, the design of the carbon nanotube/polyurethane sensor allowed formation of network micro-sized cracks which increased its reversible electrical resistance resulted in an enhancement of strain sensing. The resistance sensitivity, quantified by a gauge factor, increased more than hundredfold in case of a pre-strained sensor with Ag decorated nanotubes in comparison with the sensor with pristine nanotubes.

Selection of best impregnated palm shell activated carbon (PSAC) for simultaneous removal of SO2 and NOx

International Nuclear Information System (INIS)

Sumathi, S.; Bhatia, S.; Lee, K.T.; Mohamed, A.R.

2010-01-01

This work examines the impregnated carbon-based sorbents for simultaneous removal of SO 2 and NOx from simulated flue gas. The carbon-based sorbents were prepared using palm shell activated carbon (PSAC) impregnated with several metal oxides (Ni, V, Fe and Ce). The removal of SO 2 and NOx from the simulated flue gas was investigated in a fixed-bed reactor. The results showed that PSAC impregnated with CeO 2 (PSAC-Ce) reported the highest sorption capacity among other impregnated metal oxides for the simultaneous removal of SO 2 and NOx. PSAC-Ce showed the longest breakthrough time of 165 and 115 min for SO 2 and NOx, respectively. The properties of the pure and impregnated PSAC were analyzed by BET, FTIR and XRF. The physical-chemical features of the PSAC-Ce sorbent indicated a catalytic activity in both the sorption of SO 2 and NOx. The formation of both sulfate (SO 4 2- ) and nitrate (NO 3- ) species on spent PSAC-Ce further prove the catalytic role played by CeO 2 .

Impact Damage In Carbon/Epoxy And Carbon/PEEK Composites

Science.gov (United States)

Nettles, A. T.; Magold, N. J.

1991-01-01

Report describes results of drop-weight impact testing of specimens of carbon-fiber/epoxy and carbon-fiber/polyetheretherketone (PEEK) composite materials. Panels made of these materials assembled into lightweight, strong, stiff structures useful in automobiles, aircraft, sporting goods, and many other products. PEEK specimens showed less delamination than epoxy specimens at given impact energy.

Effect of epoxy resin and hardener containing microcapsules on healing efficiency of epoxy adhesive based metal joints

International Nuclear Information System (INIS)

Khan, Nazrul Islam; Halder, Sudipta; Goyat, M.S.

2016-01-01

Dual component microcapsules of epoxy resin and polyamine hardener with polymethyl methacrylate (PMMA) shell were synthesized using a water-oil-water emulsion solvent evaporation method. The high concentration of sodium dodecyl sulfate (SDS) was used to reduce the thickness of shell wall of dual component microcapsules. The dual microcapsules of 1:1 weight ratio were introduced in the epoxy adhesive to study the healing effect. The morphology, chemical structure and thermal characteristics of the microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The insertion of dual component microcapsules in epoxy matrix reduced the lap shear strength of adhesive joints, which may be attributed to the generation of stress concentration cites because of micron sized capsules. However, the extension and absorbed failure energy of adhesive joints under uniaxial loading increased with the increase of concentration of dual microcapsules. The viscoelastic nature of the dual microcapsules may be responsible for this enhancement. Significant enhancement in the healing efficiency (90.93%) of the joints was achieved for 10 wt% of dual microcapsules. The crack pinning and crack blunting mechanisms at the vicinity of the crack path adjacent to the microcapsules were found responsible for significant enhancement in the healing efficiency of the adhesive joints. - Highlights: • High SDS concentration was used to control the dual component microcapsules shell wall thickness. • Self-healing performance of dual component microcapsules reinforced epoxy adhesive based single lap joints was studied. • 90.93% of the damage healing was achieved for self-healing adhesive based single lap joints. • Increase in concentration of microcapsules reduces the lap shear properties of the self-healing joints.

Effect of epoxy resin and hardener containing microcapsules on healing efficiency of epoxy adhesive based metal joints

Energy Technology Data Exchange (ETDEWEB)

Khan, Nazrul Islam [Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar 788010, Assam (India); Halder, Sudipta, E-mail: shalder@nits.ac.in [Department of Mechanical Engineering, National Institute of Technology Silchar, Silchar 788010, Assam (India); Goyat, M.S. [Department of Physics, University of Petroleum & Energy Studies, Dehradun, Uttarakhand 248007 (India)

2016-03-01

Dual component microcapsules of epoxy resin and polyamine hardener with polymethyl methacrylate (PMMA) shell were synthesized using a water-oil-water emulsion solvent evaporation method. The high concentration of sodium dodecyl sulfate (SDS) was used to reduce the thickness of shell wall of dual component microcapsules. The dual microcapsules of 1:1 weight ratio were introduced in the epoxy adhesive to study the healing effect. The morphology, chemical structure and thermal characteristics of the microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), respectively. The insertion of dual component microcapsules in epoxy matrix reduced the lap shear strength of adhesive joints, which may be attributed to the generation of stress concentration cites because of micron sized capsules. However, the extension and absorbed failure energy of adhesive joints under uniaxial loading increased with the increase of concentration of dual microcapsules. The viscoelastic nature of the dual microcapsules may be responsible for this enhancement. Significant enhancement in the healing efficiency (90.93%) of the joints was achieved for 10 wt% of dual microcapsules. The crack pinning and crack blunting mechanisms at the vicinity of the crack path adjacent to the microcapsules were found responsible for significant enhancement in the healing efficiency of the adhesive joints. - Highlights: • High SDS concentration was used to control the dual component microcapsules shell wall thickness. • Self-healing performance of dual component microcapsules reinforced epoxy adhesive based single lap joints was studied. • 90.93% of the damage healing was achieved for self-healing adhesive based single lap joints. • Increase in concentration of microcapsules reduces the lap shear properties of the self-healing joints.

Improvement in electrical, thermal and mechanical properties of epoxy by filling carbon nanotube

Directory of Open Access Journals (Sweden)

2008-01-01

Full Text Available In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1, 0.2, 0.3, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. Electric conductivity, dynamic mechanical analysis (DMA, three point bending tests and fracture tests were then performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of materials. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased from 1014 Ω•m of neat epoxy to 10 Ω•m with 0.4% CNT. The experimental results also indicate that the frequency dependent behavior of CNT/epoxy nanocomposite can be modeled by R-C circuit, permittivity of material increase with increasing of CNT content. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17°C increase in Tg. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite.

Barium depletion study on impregnated cathodes and lifetime prediction

International Nuclear Information System (INIS)

Roquais, J.M.; Poret, F.; Doze, R. le; Ricaud, J.L.; Monterrin, A.; Steinbrunn, A.

2003-01-01

In the thermionic cathodes used in cathode ray-tubes (CRTs), barium is the key element for the electronic emission. In the case of the dispenser cathodes made of a porous tungsten pellet impregnated with Ba, Ca aluminates, the evaporation of Ba determines the cathode lifetime with respect to emission performance in the CRT. The Ba evaporation results in progressive depletion of the impregnating material inside the pellet. In the present work, the Ba depletion with time has been extensively characterized over a large range of cathode temperature. Calculations using the depletion data allowed modeling of the depletion as a function of key parameters. The link between measured depletion and emission in tubes has been established, from which an end-of-life criterion was deduced. Taking modeling into account, predicting accelerated life-tests were performed using high-density maximum emission current (MIK)

A study of thermal diffusivity of carbon-epoxy and glass-epoxy composites using the modified pulse method

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Terpiłowski Janusz

2014-09-01

Full Text Available Transient heat transfer is studied and compared in two planeparallel composite walls and one EPIDIAN 53 epoxy resin wall acting as a matrix for both composites. The first of the two walls is made of carbonepoxy composite; the other wall is made of glass-epoxy composite, both with comparable thickness of about 1 mm and the same number of carbon and glass fabric layers (four layers. The study was conducted for temperatures in the range of 20-120 °C. The results of the study of thermal diffusivity which characterizes the material as a heat conductor under transient conditions have a preliminary character. Three series of tests were conducted for each wall. Each series took about 24 h. The results from the three series were approximated using linear functions and were found between (0.7-1.35×10−7m2/s. In the whole range of temperature variation, the thermal diffusivity values for carbon-epoxy composite are from 1.2 to 1.5 times higher than those for the other two materials with nearly the same thermal diffusivity characteristics.

The influence of stiffeners on axial crushing of glass-fabric-reinforced epoxy composite shells

Directory of Open Access Journals (Sweden)

A. Vasanthanathan

2017-01-01

Full Text Available A generic static and impact experimental procedure has been developed in this work aimed at improving the stability of glass fabric reinforced epoxy shell structures by bonding with axial stiffeners. Crashworthy structures fabricated from composite laminate with stiffeners would offer energy absorption superior to metallic structures under compressive loading situations. An experimental material characterisation of the glass fabric reinforced epoxy composite under uni-axial tension has been carried out in this study. This work provides a numerical simulation procedure to describe the static and dynamic response of unstiffened glass fabric reinforced epoxy composite shell (without stiffeners and stiffened glass fabric reinforced epoxy composite shell (with axial stiffeners under static and impact loading using the Finite Element Method. The finite element calculation for the present study was made with ANSYS®-LS-DYNA® software. Based upon the experimental and numerical investigations, it has been asserted that glass fabric reinforced epoxy shells stiffened with GFRP stiffeners are better than unstiffened glass fabric reinforced epoxy shell and glass fabric reinforced epoxy shell stiffened with aluminium stiffeners. The failure surfaces of the glass fabric reinforced epoxy composite shell structures tested under impact were examined by SEM.

Synthesis and characterization of rubbery epoxy/organoclay hectorite nanocomposites

Directory of Open Access Journals (Sweden)

2007-12-01

Full Text Available The present research investigates the morphology, the mechanical, and the viscoelastic properties of rubbery epoxy/clay nanocomposites synthesized by in situ polymerisation of a prepolymer diglycidyl ether of bisphenol-A crosslinked with an aliphatic diamine based on a polyoxypropylene backbone. The inorganic phase was hectorite, exchanged with octadecylammonium ions in order to give organophilic properties to the phyllosilicate. An ultrasonicator was used to disperse the silicate clay layer into epoxy-amine matrix. The morphology of epoxy-hectorite nanocomposites examined by transmission electron microscopy (TEM showed that mixed delamination or intercalation or microdispersion could occur depending on type of organoclay. Moreover, the mechanical and viscoelastic properties were found to be improved with only the treated hectorite.

Epoxy coatings for anticorrosion challenges: a link between chemistry and performance?

Energy Technology Data Exchange (ETDEWEB)

Sauvant-Moynot, Valerie; Schweitzer, Sylvie; Grenier, Jacky; Duval, Sebastien [Institut Francais du Petrole, 1 et 4 avenue Bois Preau, 92450 Rueil-Malmaison (France)

2004-07-01

Epoxy coatings have been used extensively for pipeline protection in the oil and gas industries over the past decades. Thank to their outstanding adhesive properties, epoxy resins are classically used for external coating of offshore pipelines although cathodic protection is applied. They provide corrosion protection while being used as neat coating or as primer layer in a three-layer coating. Protection of internal pipelines devoted to gas transport is another application of epoxy coatings. Whatever the case, the choice of the right epoxy formulation should be adapted to the service conditions, namely exposition medium and temperature, in order to provide efficient and sustainable corrosion protection. Epoxy resins constitute a wide family and classical formulations may not fulfill the requirements of today's challenges: as pipelines are require d to operate in more and more difficult conditions, coatings are expected to function in higher temperature conditions; additionally, practical conditions such as temporary injection of methanol make the environmental exposure of the epoxy coating harsher. Therefore, there is a need of a better knowledge of technical performance and limitations of high temperature epoxy resins. This paper examined the influence of the epoxy network architecture on their protection properties and durability while exposed to distilled / sea water at 110 deg. C and to methanol at room temperature. The objective was to investigate the link between resin chemistry and final performance with respect to anticorrosion applications. Five epoxy resin formulations mixed in stoichiometric proportions were cured and post-cured to infinite extent in order to achieve densely cross-linked networks exhibiting controlled and reproducible architectures. Gravimetric and pressurised differential scanning calorimetry (DSC) measurements were performed to evaluate the plasticization effect of both water and methanol on formulations under study. The related

Flame resistant hybrid epoxy composites

Czech Academy of Sciences Publication Activity Database

Śliwa, R.; Oleksy, M.; Heneczkowski, M.; Oliwa, R.; Budzik, G.; Kozik, B.; Markowska, O.; Strachota, Adam

2015-01-01

Roč. 60, č. 10 (2015), s. 667-670 ISSN 0032-2725 Institutional support: RVO:61389013 Keywords : epoxy resin * quaternary phosphonium salts * modified bentonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.718, year: 2015

Characterization and analysis of epoxy/clay nanotubes composites; Cacaterizacao e analise de compositos de epoxi, argila e nanotubos de carbono

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

An DGEBA epoxy matrix was used aiming to achieve a nanocomposite material, through the dispersion of (CNT) via mechanical stirring followed by sonication. In this work the following characterization were performed: mechanical characterization, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WXRD) and scanning electron microscopy (SEM). The addition of CNT and modified clays promoted the increase of modulus of the epoxy matrix, and a synergistic effect between CNT and both clays could be presumed. SEM images of the fracture surface show the difference between the fracture surface area and the presence of clusters among the samples, allowing a correlation with the modulus of elasticity. X-ray diffractograms from 2{Theta} = 5 deg showed no peaks for modified clay samples, however it is possible to affirm that modified clay platelets are forming a less organized structure compared to the structure of the clay as natural in epoxy. (author)

Novel epoxy activated hydrogels for solving lactose intolerance.

Science.gov (United States)

Elnashar, Magdy M M; Hassan, Mohamed E

2014-01-01

"Lactose intolerance" is a medical problem for almost 70% of the world population. Milk and dairy products contain 5-10% w/v lactose. Hydrolysis of lactose by immobilized lactase is an industrial solution. In this work, we succeeded to increase the lactase loading capacity to more than 3-fold to 36.3 U/g gel using epoxy activated hydrogels compared to 11 U/g gel using aldehyde activated carrageenan. The hydrogel's mode of interaction was proven by FTIR, DSC, and TGA. The high activity of the epoxy group was regarded to its ability to attach to the enzyme's -SH, -NH, and -OH groups, whereas the aldehyde group could only bind to the enzyme's -NH2 group. The optimum conditions for immobilization such as epoxy chain length and enzyme concentration have been studied. Furthermore, the optimum enzyme conditions were also deliberated and showed better stability for the immobilized enzyme and the Michaelis constants, K m and V max, were doubled. Results revealed also that both free and immobilized enzymes reached their maximum rate of lactose conversion after 2 h, albeit, the aldehyde activated hydrogel could only reach 63% of the free enzyme. In brief, the epoxy activated hydrogels are more efficient in immobilizing more enzymes than the aldehyde activated hydrogel.

Electrically Conductive Epoxy Adhesives

Directory of Open Access Journals (Sweden)

Lan Bai

2011-02-01

Full Text Available Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

Electroactive polymer gels based on epoxy resin

Science.gov (United States)

Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

2007-04-01

Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

Quantitative Study of Interface/Interphase in Epoxy/Graphene-Based Nanocomposites by Combining STEM and EELS.

Science.gov (United States)

Liu, Yu; Hamon, Ann-Lenaig; Haghi-Ashtiani, Paul; Reiss, Thomas; Fan, Benhui; He, Delong; Bai, Jinbo

2016-12-14

A quantitative study of the interphase and interface of graphene nanoplatelets (GNPs)/epoxy and graphene oxide (GO)/epoxy was carried out by combining scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). The interphase regions between GNPs and epoxy matrix were clearly identified by the discrepancy of the plasmon peak positions in the low energy-loss spectra due to different valence electron densities. The spectrum acquisitions were carried out along lines across the interface. An interphase thickness of 13 and 12.5 nm was measured for GNPs/epoxy and GO/epoxy, respectively. The density of the GNPs/epoxy interphase was 2.89% higher than that of the epoxy matrix. However, the density of the GO/epoxy interphase was 1.37% lower than that of the epoxy matrix. The interphase layer thickness measured in this work is in good agreement with the transition layer theory, which proposed an area with modulus linearly varying across a finite width. The results provide an insight into the interphase for carbon-based polymer composites that can help to design the functionalization of nanofillers to improve the composite properties.

Impregnation of β-tricalcium phosphate robocast scaffolds by in situ polymerization.

Science.gov (United States)

Martínez-Vázquez, Francisco J; Perera, Fidel H; van der Meulen, Inge; Heise, Andreas; Pajares, Antonia; Miranda, Pedro

2013-11-01

Ring-opening polymerization of ε-caprolactone (ε-CL) and L-lactide (LLA) was performed to impregnate β-tricalcium phosphate (β-TCP) scaffolds fabricated by robocasting. Concentrated colloidal inks prepared from β-TCP commercial powders were used to fabricate porous structures consisting of a 3D mesh of interpenetrating rods. ε-CL and LLA were in situ polymerized within the ceramic structure by using a lipase and stannous octanoate, respectively, as catalysts. The results show that both the macropores inside the ceramic mesh and the micropores within the ceramic rods are full of polymer in either case. The mechanical properties of scaffolds impregnated by in situ polymerization (ISP) are significantly increased over those of the bare structures, exhibiting similar values than those obtained by other, more aggressive, impregnation methods such as melt-immersion (MI). ISP using enzymatic catalysts requires a reduced processing temperature which could facilitate the incorporation of growth factors and other drugs into the polymer composition, thus enhancing the bioactivity of the composite scaffold. The implications of these results for the optimization of the mechanical and biological performance of scaffolds for bone tissue engineering applications are discussed. Copyright © 2013 Wiley Periodicals, Inc.

Chiral separation of amino-alcohols using extractant impregnated resins

NARCIS (Netherlands)

Babic, K.; Driessen, G.H.M.; van der Ham, Aloysius G.J.; de Haan, A.B.

2007-01-01

The performance of extractant impregnated resin (EIR) technology for chiral separation of amino-alcohols has been investigated. Phenylglycinol was selected as an archetype model enantiomer and azophenolic crown ether was used as a versatile enantioselective extractant. 1-Phenyloctane was selected as

Partial-impregnation techniques in the production of wood-polymer composites through gamma irradiation

International Nuclear Information System (INIS)

Du Plessis, T.A.; Du Toit, G.S.; Jurriaanse, A.

1977-04-01

Radiation-processed wood-polymer composites produced from various partially impregnated Pinus species grown in South Africa were investigated and compared to a number of locally available noble hardwoods in respect of dimensional stability, hardness, homogeneity and weathering properties. This investigation clearly demonstrates that, through partial-impregnation techniques, wood-polymer composites can be formed from the locally grown Pinus species with a considerable saving in monomer costs without sacrificing most of the important physical properties of these materials [af

Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

Science.gov (United States)

Periolatto, M.; Sangermano, M.; Spena, P. Russo

2016-05-01

A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

Energy Technology Data Exchange (ETDEWEB)

Periolatto, M.; Spena, P. Russo [Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, Bolzano (Italy); Sangermano, M. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino (Italy)

2016-05-18

A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

International Nuclear Information System (INIS)

Periolatto, M.; Spena, P. Russo; Sangermano, M.

2016-01-01

A transparent, water vapor barrier film made of an epoxy resin and graphene oxide (GO) was synthesized by photopolymerization process. The epoxy/GO film with just 0.05 wt% GO gives a 93% WVTR reduction with respect to the pristine polymer, reaching barrier properties better than other polymer composites containing higher amounts of graphene. The excellent water vapor barrier is attributed to the good dispersion of GO in the polymer matrix. Moreover, GO significantly enhances the toughness and the damping capacity of the epoxy resins. The hybrid film can have potential applications in anticorrosive coatings, electronic devices, pharmaceuticals and food packaging.

Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

Science.gov (United States)

M El Saeed, Ashraf; Abd El-Fattah, M; Azzam, Ahmed M; Dardir, M M; Bader, Magd M

2016-08-01

Cuprous oxide is commonly used as a pigment; paint manufacturers begin to employ cuprous oxide as booster biocides in their formulations, to replace the banned organotins as the principal antifouling compounds. Epoxy coating was reinforced with cuprous oxide nanoparticles (Cu2O NPs). The antibacterial as well as antifungal activity of Cu2O epoxy nanocomposite (Cu2O EN) coating films was investigated. Cu2O NPs were also experimented for antibiofilm and time-kill assay. The thermal stability and the mechanical properties of Cu2O EN coating films were also investigated. The antimicrobial activity results showed slowdown, the growth of organisms on the Cu2O EN coating surface. TGA results showed that incorporating Cu2O NPs into epoxy coating considerably enhanced the thermal stability and increased the char residue. The addition of Cu2O NPs at lower concentration into epoxy coating also led to an improvement in the mechanical resistance such as scratch and abrasion. Cu2O NPs purity was confirmed by XRD. The TEM photograph demonstrated that the synthesized Cu2O NPs were of cubic shape and the average diameter of the crystals was around 25nm. The resulting perfect dispersion of Cu2O NPs in epoxy coating revealed by SEM ensured white particles embedded in the epoxy matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

The non-isothermal DSC kinetics of polyethylene tereftalate–epoxy compatible blends

International Nuclear Information System (INIS)

Zvetkov, V.L.; Djoumaliisky, S.; Simeonova-Ivanova, E.

2013-01-01

Highlights: ► The non-isothermal DSC kinetics of the reaction of DGEBA with DDS, in particular in the presence of phase separating PET, has been studied. ► The specific features in the kinetics of PET formulations in comparison to the pure system have been discussed. ► The fast pre-curing of the epoxy phase allows supposing sub-micro phase separation of PET and efficient toughening of the epoxy matrix. - Abstract: Polyethylene tereftalate has been dissolved in an epoxy resin based on diglycidyl ether of bisphenol-A, DGEBA, and the epoxy component has been cross-linked with the aid of two diamine hardeners. Two series of samples have been tested at the epoxy-amine stoichiometry applying the differential scanning calorimetry, DSC, in scanning mode. One of the series of samples was pre-cured at low temperatures with the aid of an aliphatic diamine hardener near the gel point and post-cured with diaminodiphenyl sulfone, DDS. The other series of samples contained the higher temperature hardener only. Consequently, the experimental data obtained in this study on both systems relate to the non-isothermal curing of DGEBA with DDS. The kinetics has been estimated applying preferably isoconversional (model free) methods. It has been established that the fast pre-curing allows performing a sub-micro phase separation and efficient toughening of the epoxy matrix

The non-isothermal DSC kinetics of polyethylene tereftalate–epoxy compatible blends

Energy Technology Data Exchange (ETDEWEB)

Zvetkov, V.L., E-mail: zvetval@yahoo.com [Institute of Mechanics, Bulgarian Academy of Sciences, bl. I, Sofia 1113 (Bulgaria); Djoumaliisky, S.; Simeonova-Ivanova, E. [Institute of Mechanics, Bulgarian Academy of Sciences, bl. I, Sofia 1113 (Bulgaria)

2013-02-10

Highlights: ► The non-isothermal DSC kinetics of the reaction of DGEBA with DDS, in particular in the presence of phase separating PET, has been studied. ► The specific features in the kinetics of PET formulations in comparison to the pure system have been discussed. ► The fast pre-curing of the epoxy phase allows supposing sub-micro phase separation of PET and efficient toughening of the epoxy matrix. - Abstract: Polyethylene tereftalate has been dissolved in an epoxy resin based on diglycidyl ether of bisphenol-A, DGEBA, and the epoxy component has been cross-linked with the aid of two diamine hardeners. Two series of samples have been tested at the epoxy-amine stoichiometry applying the differential scanning calorimetry, DSC, in scanning mode. One of the series of samples was pre-cured at low temperatures with the aid of an aliphatic diamine hardener near the gel point and post-cured with diaminodiphenyl sulfone, DDS. The other series of samples contained the higher temperature hardener only. Consequently, the experimental data obtained in this study on both systems relate to the non-isothermal curing of DGEBA with DDS. The kinetics has been estimated applying preferably isoconversional (model free) methods. It has been established that the fast pre-curing allows performing a sub-micro phase separation and efficient toughening of the epoxy matrix.

Colorless triphenylamine-based aliphatic thermoset epoxy for multicolored and near-infrared electrochromic applications.

Science.gov (United States)

Chuang, Ya-Wen; Yen, Hung-Ju; Wu, Jia-Hao; Liou, Guey-Sheng

2014-03-12

In this study, two novel colorless thermoset epoxy resins with anodically electrochromism were prepared from the thermal curing of two triphenylamine-based diamine monomers, 4,4'-diamino-4″-methoxytriphenylamine (1) and N,N'-bis(4-aminophenyl)-N,N'-di(4-methoxylphenyl)-1,4-phenylenediamine (2) with aliphatic epoxy triglycidyl isocyanurate, respectively. The resulting thermoset epoxy resins showed excellent softening temperature (Ts, 270 and 280 °C) due to the rigid structure and highly crosslinking density. In addition, novel colorless epoxy resin films revealed good reversible electrochemical oxidation and interesting multi-electrochromic behavior with high contrast ratio both in visible and near-infrared regions. The aliphatic thermoset epoxy resins also exhibited high transparency in visible region as colorless and great potential for practical electrochromic applications.

Damage detection and conductivity evolution in carbon nanofiber epoxy via electrical impedance tomography

International Nuclear Information System (INIS)

Tallman, T N; Wang, K W; Gungor, S; Bakis, C E

2014-01-01

Utilizing electrically conductive nanocomposites for integrated self-sensing and health monitoring is a promising area of structural health monitoring (SHM) research wherein local changes in conductivity coincide with damage. In this research we conduct proof of concept investigations using electrical impedance tomography (EIT) for damage detection by identifying conductivity changes and by imaging conductivity evolution in a carbon nanofiber (CNF) filled epoxy composite. CNF/epoxy is examined because fibrous composites can be manufactured with a CNF/epoxy matrix thereby enabling the entire matrix to become self-sensing. We also study the mechanisms of conductivity evolution in CNF/epoxy through electrical impedance spectroscopy (EIS) testing. The results of these tests indicate that thermal expansion is responsible for conductivity evolution in a CNF/epoxy composite. (paper)

Nanoindentation study of interphases in epoxy/amine thermosetting systems modified with thermoplastics.

Science.gov (United States)

Ramos, Jose Angel; Blanco, Miren; Zalakain, Iñaki; Mondragon, Iñaki

2009-08-15

The characterization of a mixture of epoxy/amine with different stoichiometric ratios was carried out by means of nanoindentation. The epoxy system was composed by diglycidyl ether of bisphenol-A and 4,4'-methylene bis-(3-chloro 2,6-diethylaniline). Diffusion through interface formed by epoxy/amine system in stoichiometric ratio and several thermoplastic polymers was also analyzed by means of stiffness analysis, as studied by atomic force microscopy (AFM) and coupled nanoindentation tests. Used thermoplastics were an amorphous, atactic polystyrene, and two semicrystalline, syndiotactic polystyrene and poly(phenylene sulfide). Larger range diffusion was obtained in epoxy/amine systems modified with atactic polystyrene while the study of the influence of stoichiometric ratio suggests that the excess of epoxy generated stiffer material. In addition, larger indentation loads resulted in higher apparent stiffness because of the more number of polymer chains that had to re-accommodate owing to the increase in contact area.

EVALUACIÓN DEL COLOR DURANTE EL ALMACENAMIENTO DE LA PULPA DE BANANO VERDE IMPREGNADA AL VACÍO CON SOLUCIONES ANTIPARDEANTES AVALIAÇÂO DA COR NO ARMAZENAMENTO DA POLPA DE BANANA VERDE IMPREGNADA A VACUUM USANDO SOLUÇÔES PARA EVITAR O PARDEAMENTO COLOR EVALUATION DURING STORAGE OF GREEN BANANAS PULP IMPREGNATED WITH ANTIBROWNNING SOLUTIONS UNDER VACCUM

Directory of Open Access Journals (Sweden)

MISAEL CORTÉS R

2011-12-01

Full Text Available La impregnación al vacío es la técnica aplicada por la ingeniería de matrices, como mecanismo de incorporación de soluciones al interior de las matrices alimentarias. Se evaluó la evolución del color en la pulpa de banano verde (PBV (Musa cavendish a diferentes condiciones de almacenamiento: tiempo (0, 3, 6, 9, 12 y 15 días, temperatura (4, 20 y 30°C y empaque, con vacío (CV y sin vacío (SV; bajo tratamientos con sulfitos (500, 1000, 1500 mg/kg PBV y de la interacción antioxidante (60, 90, 120 mg/100 g PBV acidulantes (50, 150, 250 mg/100 g PBV. Los parámetros de color se evaluaron en el espacio CIEL*a*b*, en términos de luminosidad (L* y cromaticidad a* y b*. El ANOVA presentó diferencias estadísticas significativas (p A impregnaçáo a vacuo é é uma técnica usada pela engenharia de matrizes como um meio de incorporar soluçóes na matriz dos alimentos. Neste trabalho foram avaliados a evoluçáo da cor da polpa da banana verde (PBV (Musa cavendish para diferentes condiçóes de armazenamento: tempo (0, 3, 6, 9, 12 e 15 dias, temperatura (4, 20 e 30 °C e condiçóes de embalagem (com vácuo (CV e sem vacuo (SV, sob tratamento com sulfitos (500, 1000, 1500 mg/kg de PBV e interaçáo antioxidante (60, 90, 120 mg/100 g PBV e acidulantes (50, 150, 250 mg/100 g PBV. Os parâmetros de cor foram avaliados no sistema CIÉL*a*b*, em termos de luminosidade (L* e cromaticidade (a*,b*. A análise de variância (ANOVA apresentou diferenças significativas (p Vacuum impregnation is a technique applied by matrix engineering as the mechanism to incorporate the solutions to the interior of an alimentary matrix. The development of the color of the pulp of unripe Banana (PUB (Musa cavendish was evaluated in different storage conditions: Time 0, 3, 6, 9, 12, and 15 days, Temperature 4, 20, and 30°C, packed with vacuum (WV and without vacuum (NV under sulfite treatment (500, 1000, 1500 mg/kg PUB and the antioxidant interaction (60, 90, 120 mg

The selection and properties of epoxide resins used for the insulation of magnet systems in radiation environments

International Nuclear Information System (INIS)

Phillips, D.C.; Scott, J.M.; Goebel, K.; Schoenbacher, H.

1981-01-01

Laboratory tests have been carried out on five types of epoxy resins - four based on bisphenol A, one on hydantoin-bisphenol A - applicable in the construction of large magnet coils. Two of the resin compositions have already been used in large quantities as insulating material for magnets at the European Organization for Nuclear Research (CERN); the others were selected for comparison according to their good radiation resistance, good initial mechanical properties, and optimal properties for vacuum impregnation. Three types of tests are discussed in detail: creep, crack propagation (as a measure of toughness), and radiation resistance. The results show that the resin composition with hydantoin exhibits the best resistance to crack propagation but, on the other hand, the lowest resistance to ionizing radiation, and can therefore not be recommended for use in a radiation environment. Among the other materials based on biosphenol A, better toughness values were obtained with lower-cross-linked resin systems, whereas the radiation resistance is better for highly-cross-linked materials. It is concluded that a reasonable compromise combining good processing and operational properties with sufficiently high radiation resistance is obtained with a standard epoxy-resin-type bisphenol A with a specially formulated anhydride hardener and an amine-substituted phenol-type accelerator. (orig.)

E-Beam-Cured Layered-Silicate and Spherical Silica Epoxy Nanocomposites (Preprint)

National Research Council Canada - National Science Library

Chen, Chenggang; Anderson, David P

2007-01-01

.... The nanofillers can be two dimensional (layered-silicate) and zero dimensional (spherical silica). Both the spherical silica epoxy nanocomposite and the layered-silicate epoxy nanocomposite can be cured to a high degree of curing...

UV absorption by cerium oxide nanoparticles/epoxy composite thin films

International Nuclear Information System (INIS)

Dao, Ngoc Nhiem; Luu, Minh Dai; Nguyen, Quang Khuyen; Kim, Byung Sun

2011-01-01

Cerium oxide (CeO 2 ) nanoparticles have been used to modify properties of an epoxy matrix in order to improve the ultra-violet (UV) absorption property of epoxy thin films. The interdependence of mechanical properties, UV absorption property and the dispersed concentration of CeO 2 nanoparticles was investigated. Results showed that, by increasing the dispersed concentration of CeO 2 nanoparticles up to 3 wt%, tensile modulus increases while two other mechanical properties, namely tensile strength and elongation, decrease. The UV absorption peak and the absorption edges of the studied thin films were observed in the UV-Vis absorption spectra. By incorporating CeO 2 nanoparticles into the epoxy matrix, an absorption peak appears at around 318 nm in UV-Vis spectra with increasing CeO 2 concentration from 0.1 to 1.0 wt%. Scanning electron microscopy (SEM) images revealed that a good dispersion of nanoparticles in the epoxy matrix by an ultrasonic method was achieved

Improvement of Mechanical and Dielectric Properties of Epoxy Resin Using CNTs/ZnO Nanocomposite.

Science.gov (United States)

Vu, Pham Gia; Truc, Trinh Anh; Chinh, Nguyen Thuy; Tham, Do Quang; Trung, Tran Huu; Oanh, Vu Ke; Hang, To Thi Xuan; Olivier, Marjorie; Hoang, Thai

2018-04-01

In this study, carbon nanotubes (CNTs)/ZnO composites had been prepared using the sol-gel method and then incorporated into an epoxy resin for reinforcement of mechanical and electrical properties. Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) Field Emission Scanning Electron Microscope (FE-SEM) analyses show that the ZnO nanoparticles deposited on CNTs were crystallized in a hexagonal wurtzite structure. Average particle size of ZnO deposited on the CNT was about 8 nm. The mechanical and dielectric properties of epoxy containing CNTs/ZnO were investigated in comparison to epoxy resin and epoxy resin containing only CNT or ZnO nanoparticles. The results indicated that tensile strength and elongation at break of the nanocomposite were substantially improved with the presence of CNTs/ZnO at the equal volume. The DSC analysis associate with the dielectric results shows that the behavior of epoxy/CNTs/ZnO is identical to epoxy/ZnO composite, and the CNTs is essential to the distributed arrangement of ZnO in the epoxy resin.

Bacterial flagella as biotemplate for the synthesis of silver nanoparticle impregnated bionanomaterial

Energy Technology Data Exchange (ETDEWEB)

Gopinathan, Priya [Nanobiotechnology Laboratory, Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore, 641004 (India); Ashok, Anuradha M. [HRTEM facility, Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore, 641004 (India); Selvakumar, R., E-mail: selvabiotech@gmail.com [Nanobiotechnology Laboratory, Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore, 641004 (India)

2013-07-01

The present study was carried out to synthesize one dimensional silver nanoparticle impregnated flagellar bionanomaterial. Flagella was isolated from Salmonella typhimurium and depolymerised into flagellin monomers. The flagellin monomers were repolymerised again into flagella using suitable technique. The molecular weight of native (NF) and polymerized flagella (PF) was determined using polyacrylamide gel electrophoresis. The NF and PF were used as a template, over which silver nanoparticles were impregnated using in situ chemical reduction process. The synthesized flagellar-silver nanoparticle bionanomaterials were characterized using UV–vis, FT-IR Raman and XRD spectroscopy, and High resolution transmission electron microscopy (HR-TEM). The characterization studies confirmed the attachment of silver nanoparticles over flagella and repolymerised flagella. The size of the silver nanoparticles on the flagella and repolymerised flagella varied and was in the range of 3–11 nm. I–V characteristics of the bionanomaterials were analyzed using Kethley meter which indicated the increase of conductivity after impregnation of silver nanoparticles. The results indicated that flagellar-silver nanoparticle bionanomaterials can be used as a potential one dimensional bionanomaterials for various applications.

Bacterial flagella as biotemplate for the synthesis of silver nanoparticle impregnated bionanomaterial

International Nuclear Information System (INIS)

Gopinathan, Priya; Ashok, Anuradha M.; Selvakumar, R.

2013-01-01

The present study was carried out to synthesize one dimensional silver nanoparticle impregnated flagellar bionanomaterial. Flagella was isolated from Salmonella typhimurium and depolymerised into flagellin monomers. The flagellin monomers were repolymerised again into flagella using suitable technique. The molecular weight of native (NF) and polymerized flagella (PF) was determined using polyacrylamide gel electrophoresis. The NF and PF were used as a template, over which silver nanoparticles were impregnated using in situ chemical reduction process. The synthesized flagellar-silver nanoparticle bionanomaterials were characterized using UV–vis, FT-IR Raman and XRD spectroscopy, and High resolution transmission electron microscopy (HR-TEM). The characterization studies confirmed the attachment of silver nanoparticles over flagella and repolymerised flagella. The size of the silver nanoparticles on the flagella and repolymerised flagella varied and was in the range of 3–11 nm. I–V characteristics of the bionanomaterials were analyzed using Kethley meter which indicated the increase of conductivity after impregnation of silver nanoparticles. The results indicated that flagellar-silver nanoparticle bionanomaterials can be used as a potential one dimensional bionanomaterials for various applications.

Epoxy-based broadband antireflection coating for millimeter-wave optics.

Science.gov (United States)

Rosen, Darin; Suzuki, Aritoki; Keating, Brian; Krantz, William; Lee, Adrian T; Quealy, Erin; Richards, Paul L; Siritanasak, Praween; Walker, William

2013-11-20

We have developed epoxy-based, broadband antireflection coatings for millimeter-wave astrophysics experiments with cryogenic optics. By using multiple-layer coatings where each layer steps in dielectric constant, we achieved low reflection over a wide bandwidth. We suppressed the reflection from an alumina disk to 10% over fractional bandwidths of 92% and 104% using two-layer and three-layer coatings, respectively. The dielectric constants of epoxies were tuned between 2.06 and 7.44 by mixing three types of epoxy and doping with strontium titanate powder required for the high dielectric mixtures. At 140 K, the band-integrated absorption loss in the coatings was suppressed to less than 1% for the two-layer coating, and below 10% for the three-layer coating.

Improvement in tribological properties of atmospheric plasma-sprayed WC-Co coating followed by Cu electrochemical impregnation

International Nuclear Information System (INIS)

Yuan Jianhui; Zhu Yingchun; Zheng Xuebing; Ruan Qichao; Ji Heng

2009-01-01

The WC-Co coating obtained by atmospheric plasma spraying (APS) was modified by Cu electrochemical impregnation. The copper has infiltrated into and filled up the pores in WC-Co coating. The tribological properties of the coating against the stainless steel ball as sliding pairs were investigated with a ball-on-disc (BOD) configuration in air at room temperature. The as-prepared samples were characterized by means of optical microscope, scanning electron microscope and X-ray diffraction. It was found that the frictional behavior of the WC-Co coating followed by Cu electrochemical impregnation was superior to that of WC-Co coating. The wear mechanism of the WC-Co coating followed by Cu electrochemical impregnation was microcutting, whilst that of a WC-Co coating was the fatigue wear. The improvement in tribological properties of the WC-Co coating followed by Cu electrochemical impregnation was attributed to the formation of self-lubricating Cu film on the wear surface which induces the transformation of wear mechanism.

Property-porosity relationships for polymer-impregnated superconducting ceramic composite

International Nuclear Information System (INIS)

Salib, S.; Vipulanandan, C.

1990-01-01

A thermoplastic polymer, poly(methyl methacrylate) (PMMA), was used to improve the flexural properties of the high-temperature superconducting ceramic (YBa 2 Cu 3 O 7-δ ). Ceramic specimens with different porosities were prepared by dry compacting 12.5-mm-diameter disk specimens at various uniaxial pressures. Density-pressure relationships have been developed for before- and after-sintering conditions. The PMMA polymer was impregnated into the porous ceramic at room temperature. The mechanical properties were evaluated by concentrically loading simply supported disk specimens. The load-displacement responses were analyzed using the finite-element method. Impregnation of PMMA polymer at room temperature increased the flexural strength and modulus of the superconducting ceramic without affecting its electrical properties. The flexural properties depended on the porosity of the ceramics, and, hence, linear and nonlinear property-porosity relationships have been used to characterize the behavior of superconducting ceramic with an without the polymer

Protection of Steel Rebar in Salt-Contaminated Cement Mortar Using Epoxy Nanocomposite Coatings

Directory of Open Access Journals (Sweden)

The Huu Nguyen

2018-01-01

Full Text Available Epoxy reinforced with two kinds of nanoparticles dealing with nano-SiO2 and nano-Fe2O3 was coated on steel rebar embedded in a chloride contaminated cement mortar. NaCl was added to the fresh Portland cement paste (at 0.3% and 0.5% by weight of cement to simulate the chloride contamination at the critical level. The effect of incorporating nanoparticles on the corrosion resistance of epoxy-coated steel rebar was investigated by linear potentiodynamic polarization and electrochemical impedance spectroscopy. For the 0.3 wt.% chloride mortars, the electrochemical monitoring of the coated steel rebars during immersion for 56 days in 0.1 M NaOH solutions suggested the beneficial role of nano-Fe2O3 particles in significantly improving the corrosion resistance of the epoxy-coated rebar. After 56 days of immersion, the nano-Fe2O3 reduced the corrosion current of epoxy-coated rebar by a factor of 7.9. When the chloride concentration in the cement mortar was 0.5 wt.%, the incorporation of nanoparticles into the epoxy matrix did not enhance the corrosion resistance of epoxy coating for the rebar. At this critical level, chloride ions initiated rebar corrosion through nanoparticles at the epoxy/rebar interface.

Characterization and analysis of epoxy/clay nanotubes composites

International Nuclear Information System (INIS)

Sene, Tarcisio S.; Kock, Thyago; Coelho, Luiz A.F.; Becker, Daniela

2011-01-01

An DGEBA epoxy matrix was used aiming to achieve a nanocomposite material, through the dispersion of (CNT) via mechanical stirring followed by sonication. In this work the following characterization were performed: mechanical characterization, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WXRD) and scanning electron microscopy (SEM). The addition of CNT and modified clays promoted the increase of modulus of the epoxy matrix, and a synergistic effect between CNT and both clays could be presumed. SEM images of the fracture surface show the difference between the fracture surface area and the presence of clusters among the samples, allowing a correlation with the modulus of elasticity. X-ray diffractograms from 2Θ = 5 deg showed no peaks for modified clay samples, however it is possible to affirm that modified clay platelets are forming a less organized structure compared to the structure of the clay as natural in epoxy. (author)

Thin layer chromatography of glucose and sorbitol on Cu(II)-impregnated silica gel plates

Energy Technology Data Exchange (ETDEWEB)

Hadzija, O. (Ruder Boskovic Inst., Zagreb (Croatia)); Spoljar, B. (Ruder Boskovic Inst., Zagreb (Croatia)); Sesartic, L. (Inst. of Immunology, Zagreb (Croatia))

1994-04-01

A thin-layer chromatographic (TLC) separation of glucose and sorbitol on CU(II)-impregnated silica gel plates with n-propanol: Water (4:1) v/v as developer and potassium permanganate as detecting reagent has been worked out. The new impregnant is completely insoluble in water and thus enables the use of an aqueous developer. The R[sub f]-values are 55 and 10 for glucose and sorbitol, respectively. (orig.)

Arsenic removal using silver-impregnated Prosopis spicigera L ...

African Journals Online (AJOL)

Arsenic removal using silver-impregnated Prosopis spicigera L. wood (PSLW) activated carbon: batch and column studies. ... Arsenic uptake has no regular trend with increasing pH; contains two adsorption maxima, the first adsorption maximum at pH 4.0 and a second adsorption maximum at pH 10.0. The extent of As (III) ...

Hydrothermal ageing of glass/epoxy composites for wind turbine blades

NARCIS (Netherlands)

Rocha, I.B.C.M.; Raijmaekers, S.; Nijssen, R.P.L.; Van der Meer, F.P.

2015-01-01

In this work, a glass/epoxy material system commonly applied in wind turbine design was used to evaluate damage processes brought by water ingression during service life. Composite short-beams and neat epoxy beams and dog-bones were conditioned by water immersion at 50º until saturation and tested

Nickel-catalyzed regio- and enantioselective aminolysis of 3,4-epoxy alcohols.

Science.gov (United States)

Wang, Chuan; Yamamoto, Hisashi

2015-04-08

The first catalytic regio- and enantioselective aminolysis of 3,4-epoxy alcohols has been accomplished. Under the catalysis of Ni(ClO4)2·6H2O, the C4 selective ring opening of various 3,4-epoxy alcohols proceeded in a stereospecific manner with high regioselectivities. Furthermore, with the Ni-BINAM catalytic system the enantioselective ring opening of 3,4-epoxy alcohols furnished various γ-hydroxy-δ-amino alcohols as products with complete regiocontrol and high enantioselectivities (up to 94% ee).

Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

OpenAIRE

Maria Elena Arce; Miguel Angel Alvarez Feijoo; Andres Suarez Garcia; Claudia C. Luhrs

2018-01-01

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the sa...

MEA vacuum system

International Nuclear Information System (INIS)

Stroo, R.; Schwebke, H.; Heine, E.

1984-01-01

This report describes construction and operation of the MEA vacuum system of NIKHEF (Netherlands). First, the klystron vacuum system, beam transport system, diode pump and a triode pump are described. Next, the isolation valve and the fast valves of the vacuum system are considered. Measuring instruments, vacuum system commands and messages of failures are treated in the last chapter. (G.J.P.)

Creep behavior of an epoxy resin and an epoxy-based FRP in condition of simultaneous supply of radiation and stress at cryogenic temperatures

International Nuclear Information System (INIS)

Nishiura, Tetsuya; Nishijima, Shigehiro; Okada, Toichi

1995-01-01

Creep tests of an epoxy resin and an epoxy-based FRP in bending under irradiation condition have been carried out, to investigate the synergistic effects of radiation and stress on mechanical properties of FRP. Simultaneous supply of stress and irradiation on the epoxy resin and the FRP enhanced creep rates in comparison with that supply of the stress on a post-irradiated one did. ESR spectra measurement was also carried out to study the change of molecule of the resin irradiated. Increase of molecular weight between crosslinks was found out to be enhanced by the synergistic effect of radiation and stress. The mechanism of increased damage of FRP induced by the effects of simultaneous stress and irradiation is discussed. (author)

Determination of Young's modulus of epoxy coated polyethylene micro-cantilever using phase-shift shadow moiré method

Science.gov (United States)

Lim, J. H.; Ratnam, M. M.; Azid, I. A.; Mutharasu, D.

2011-11-01

Young's moduli of various epoxy coated polyethylene terephthalate (PET) micro-cantilevers were determined from the deflection results obtained using the phase-shift shadow moiré (PSSM) method. The filler materials for epoxy coatings were aluminum and graphite powders that were mixed with epoxy at various percentages. Young's moduli were calculated from theory based on the deflection results. The PET micro-cantilever coated with aluminum-epoxy coating showed increasing value of Young's modulus when the ratios of the aluminum-epoxy were increased. The graphite-epoxy coating on the PET micro-cantilever also showed the same trend. The experimental results also show that Young's modulus of the graphite-epoxy coating is higher than aluminum-epoxy coating in comparison at the same mixing ratio.

Preparation, Characterization, and Modeling of Carbon Nanofiber/Epoxy Nanocomposites

Directory of Open Access Journals (Sweden)

Lan-Hui Sun

2011-01-01

Full Text Available There is a lack of systematic investigations on both mechanical and electrical properties of carbon nanofiber (CNF-reinforced epoxy matrix nanocomposites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nanocomposites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nanocomposites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nanocomposite with a 1.0 wt% CNFs. The alternate-current (AC electrical properties of the CNF/epoxy nanocomposites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt% (0.058 vol% CNFs and by ten orders of magnitude for nanocomposites with CNF volume fractions higher than 1.0 wt% (0.578 vol%. The percolation threshold (i.e., the critical CNF volume fraction is found to be at 0.057 vol%.

Tailored SWCNT functionalization optimized for compatibility with epoxy matrices

International Nuclear Information System (INIS)

Martinez-Rubi, Y; Kingston, C T; Daroszewska, M; Barnes, M; Simard, B; Gonzalez-Dominguez, J M; Ansón-Casaos, A; Martinez, M T; Hubert, P; Cattin, C

2012-01-01

We have modified single walled carbon nanotubes (SWCNTs) with well defined matrix-based architectures to improve interface interaction in SWCNT/epoxy composites. The hardener and two pre-synthesized oligomers containing epoxy and hardener moieties were covalently attached to the SWCNT walls by in situ diazonium or carboxylic coupling reactions. In this way, SWCNTs bearing amine or epoxide-terminated fragments of different molecular weights, which resemble the chemical structure of the cured resin, were synthesized. A combination of characterization techniques such as Raman and infrared absorption (FTIR) spectroscopy, elemental analysis and coupled thermogravimetry-FTIR spectroscopy were used to identify both the functional groups and degree of functionalization of SWCNTs synthesized by the laser ablation and arc-discharge methods. Depending on the type of reaction employed for the chemical functionalization and the molecular weight of the attached fragment, it was possible to control the degree of functionalization and the electronic properties of the functionalized SWCNTs. Improved dispersion of SWCNTs in the epoxy matrix was achieved by direct integration without using solvents, as observed from optical microscopy and rheology measurements of the SWCNT/epoxy mixtures. Composite materials using these fillers are expected to exhibit improved properties while preserving the thermosetting architecture. (paper)

AC electrical breakdown phenomena of epoxy/layered silicate nanocomposite in needle-plate electrodes.

Science.gov (United States)

Park, Jae-Jun; Lee, Jae-Young

2013-05-01

Epoxy/layered silicate nanocomposite for the insulation of heavy electric equipments were prepared by dispersing 1 wt% of a layered silicate into an epoxy matrix with a homogenizing mixer and then AC electrical treeing and breakdown tests were carried out. Wide-angle X-ray diffraction (WAXD) analysis and transmission electron microscopy (TEM) observation showed that nano-sized monolayers were exfoliated from a multilayered silicate in the epoxy matrix. When the nano-sized silicate layers were incorporated into the epoxy matrix, the breakdown rate in needle-plate electrode geometry was 10.6 times lowered than that of the neat epoxy resin under the applied electrical field of 520.9 kV/mm at 30 degrees C, and electrical tree propagated with much more branches in the epoxy/layered silicate nanocomposite. These results showed that well-dispersed nano-sized silicate layers retarded the electrical tree growth rate. The effects of applied voltage and ambient temperature on the tree initiation, growth, and breakdown rate were also studied, and it was found that the breakdown rate was largely increased, as the applied voltage and ambient temperature increased.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-02-20

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

The Effect of Nanoparticles Percentage on Mechanical Behavior of Silica-Epoxy Nanocomposites

International Nuclear Information System (INIS)

Islam, M.S.; Masoodi, R.; Rostami, H.

2013-01-01

Silica-epoxy nanocomposites are very common among nanocomposites, which makes them very important. Several researchers have studied the effect of nanoparticle’s size, shape, and loading on mechanical behavior of silica-epoxy nanocomposites. This paper reviews the most important research done on the effect of nanoparticle loading on mechanical properties of silica-epoxy nanocomposites. While the main focus is the tensile behavior of nanocomposite, the compressive behavior and flexural behavior were also reviewed. Finally, some of the published experimental data were combined in the graphs, using dimensionless parameters. Later, the best fitted curves were used to derive some empirical formulas for mechanical properties of silica-epoxy nanocomposites as functions of weight or volume fraction of nanoparticles.

Novel Epoxy Activated Hydrogels for Solving Lactose Intolerance

Directory of Open Access Journals (Sweden)

Magdy M. M. Elnashar

2014-01-01

Full Text Available “Lactose intolerance” is a medical problem for almost 70% of the world population. Milk and dairy products contain 5–10% w/v lactose. Hydrolysis of lactose by immobilized lactase is an industrial solution. In this work, we succeeded to increase the lactase loading capacity to more than 3-fold to 36.3 U/g gel using epoxy activated hydrogels compared to 11 U/g gel using aldehyde activated carrageenan. The hydrogel’s mode of interaction was proven by FTIR, DSC, and TGA. The high activity of the epoxy group was regarded to its ability to attach to the enzyme’s –SH, –NH, and –OH groups, whereas the aldehyde group could only bind to the enzyme’s –NH2 group. The optimum conditions for immobilization such as epoxy chain length and enzyme concentration have been studied. Furthermore, the optimum enzyme conditions were also deliberated and showed better stability for the immobilized enzyme and the Michaelis constants, Km and Vmax, were doubled. Results revealed also that both free and immobilized enzymes reached their maximum rate of lactose conversion after 2 h, albeit, the aldehyde activated hydrogel could only reach 63% of the free enzyme. In brief, the epoxy activated hydrogels are more efficient in immobilizing more enzymes than the aldehyde activated hydrogel.

Interlaminar fracture in woven carbon/epoxy laminates

Directory of Open Access Journals (Sweden)

Paulo N.B. Reis

2014-10-01

Full Text Available This paper describes an experimental study developed to characterize the mode I and mode II fracture toughness of carbon/epoxy woven composites, using DCB and ENF tests, respectively. The laminates were manufactured using an epoxy resin and twelve woven balanced bi-directional layers of carbon fibres, all of them with the same orientation (0/90º. Significant instantaneous delaminations were observed particularly for the DCB specimen, which were responsible for an oscillatory behaviour of GI versus crack length. The maximum values obtained for GIC and GIIC were 281 and 1800 J/m2, respectively.

Control of pore size in epoxy systems.

Energy Technology Data Exchange (ETDEWEB)

Sawyer, Patricia Sue; Lenhart, Joseph Ludlow (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Kallam, Alekhya (North Dakota State University, Fargo, ND); Majumdar, Partha (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J. (North Dakota State University, Fargo, ND); Celina, Mathias C.; Bahr, James (North Dakota State University, Fargo, ND); Klein, Robert J.

2009-01-01

Both conventional and combinatorial approaches were used to study the pore formation process in epoxy based polymer systems. Sandia National Laboratories conducted the initial work and collaborated with North Dakota State University (NDSU) using a combinatorial research approach to produce a library of novel monomers and crosslinkers capable of forming porous polymers. The library was screened to determine the physical factors that control porosity, such as porogen loading, polymer-porogen interactions, and polymer crosslink density. We have identified the physical and chemical factors that control the average porosity, pore size, and pore size distribution within epoxy based systems.

Insulation vacuum and beam vacuum overpressure release

CERN Document Server

Parma, V

2009-01-01

There is evidence that the incident of 19th September caused a high pressure build-up inside the cryostat insulation vacuum which the existing overpressure devices could not contain. As a result, high longitudinal forces acting on the insulation vacuum barriers developed and broke the floor and the floor fixations of the SSS with vacuum barriers. The consequent large longitudinal displacements of the SSS damaged chains of adjacent dipole cryo-magnets. Estimates of the helium mass flow and the pressure build- up experienced in the incident are presented together with the pressure build-up for an even more hazardous event, the Maximum Credible Incident (MCI). The strategy of limiting the maximum pressure by the installation of addition pressure relieve devices is presented and discussed. Both beam vacuum lines were ruptured during the incident in sector 3-4 giving rise to both mechanical damage and pollution of the system. The sequence, causes and effects of this damage will be briefly reviewed. We will then an...

Silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine for carbon dioxide capture under the flue gas condition

Energy Technology Data Exchange (ETDEWEB)

Lee, Min-Sang; Park, Soo-Jin, E-mail: sjpark@inha.ac.kr

2015-03-15

In this study, silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine (PEI) were prepared via a two-step process: (i) hydrolysis of tetraethylorthosilicate onto multi-walled carbon nanotubes, and (ii) impregnation of PEI. The adsorption properties of CO{sub 2} were investigated using CO{sub 2} adsorption–desorption isotherms at 298 K and thermogravimetric analysis under the flue gas condition (15% CO{sub 2}/85% N{sub 2}). The results obtained in this study indicate that CO{sub 2} adsorption increases after impregnation of PEI. The increase in CO{sub 2} capture was attributed to the affinity between CO{sub 2} and the amine groups. CO{sub 2} adsorption–desorption experiments, which were repeated five times, also showed that the prepared adsorbents have excellent regeneration properties. - Graphical abstract: Fabrication and CO{sub 2} adsorption process of the S-MWCNTs impregnated with PEI. - Highlights: • Silica coated-MWCNT impregnated with PEI was synthesized. • Amine groups of PEI gave CO{sub 2} affinity sites on MWCNT surfaces. • The S-MWCNT/PEI(50) exhibited the highest CO{sub 2} adsorption capacity.

Influence of impregnation by inorganic substances on the yield of pyrolysis products

Energy Technology Data Exchange (ETDEWEB)

Shevkoplyas, V N; Saranchuk, V I [AN Ukrainskoj SSR, Donetsk (Ukraine). Inst. Fiziko-Organicheskoj Khimii i Uglekhimii

1998-09-01

In papers was shown that fossil coals impregnation by aqueous solution of inorganic substances with a subsequent pyrolysis leads to the rise of the rate and depth of its organic mass destruction into liquid and gaseous products. This is, apperently, conditioned by changes in coals structure already on the stage of treatment. But, there are few papers that study an activating effect of inorganic reactants upon natural coals structure and their behaviour at pyrolysis. One of the methods which allows to judge structural transformation in coals at their impregnation by inorganic substances is an X-ray analysis. (orig.)

Preparation of a bio-based epoxy with comparable properties to those of petroleum-based counterparts

Directory of Open Access Journals (Sweden)

X. Q. Liu

2012-04-01

Full Text Available In this paper a bio-based epoxy with outstanding thermal and mechanical properties was synthesized using a rosin-based epoxy monomer and a rosin-based curing agent. The chemical structures of rosin based epoxy monomer and curing agent were confirmed by Nuclear Magnetic Resonance (NMR and Fourier Transform Infrared (FT-IR spectra. The flexural mechanical and dynamic mechanical properties as well as thermal stability of the cured epoxy were investigated. The results showed that the cured epoxy exhibited a glass transition temperature (Tg of 164°C and its flexural strength and modulus were as high as 70 and 2200 MPa, respectively. This indicated that a wholly bio-based epoxy resin possessing high performance was successfully obtained.

3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces

Science.gov (United States)

Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

2016-04-01

Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity.

Wear Behavior of Woven Roving Aramid / Epoxy Composite under Different Conditions

Directory of Open Access Journals (Sweden)

Asad A. Khalid

2012-09-01

Full Text Available Wear behavior studies of aramid woven roving /epoxy composite has been conducted. Sliding the material against smooth steel counter face under dry and  lubricated with oil conditions has been investigated. Powder of Silicon carbide has been mixed with the epoxy resin and tested also. The powder was mixed in a volumetric fraction of 10% with the epoxy resin. Four Laminates of six layers were fabricated by hand lay up  method. A pin on disc apparatus has been fabricated to conduct the sliding wear tests on specimens of (4 mm   4 mm   12 mm in size have been cut from the four laminates. The effect of sliding condition including dry, lubricated, dry with additives and lubricated with additives have been studied. Wear rate tests have been conducted at different sliding speeds and loads. Results show that the wear characteristics are influenced by the operating conditions and the construction of the composite material used. It was also found that the wear of aramid /epoxy composite onto the steel counter face were significantly reduced by using lubricant and additives but still took place.Keywords: Wear, Composite materials, Woven roving aramid, Epoxy, Additives, Lubricant.

The thermal properties of a carbon nanotube-enriched epoxy: Thermal conductivity, curing, and degradation kinetics

KAUST Repository

Ventura, Isaac Aguilar

2013-05-31

Multiwalled carbon nanotube-enriched epoxy polymers were prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes (COOH-MWCNTs). Three weight ratio configurations (0.05, 0.5, and 1.0 wt %) of COOH-MWCNTs were considered and compared with neat epoxy and ethanol-treated epoxy to investigate the effects of nano enrichment and processing. Here, the thermal properties of the epoxy polymers, including curing kinetics, thermal conductivity, and degradation kinetics were studied. Introducing the MWCNTs increased the curing activation energy as revealed by differential scanning calorimetry. The final thermal conductivity of the 0.5 and 1.0 wt % MWCNT-enriched epoxy samples measured by laser flash technique increased by up to 15% compared with the neat material. The activation energy of the degradation process, investigated by thermogravimetric analysis, was found to increase with increasing CNT content, suggesting that the addition of MWCNTs improved the thermal stability of the epoxy polymers. © 2013 Wiley Periodicals, Inc.

Effect of electron beam irradiation on thermal and mechanical properties of aluminum based epoxy composites

Science.gov (United States)

Visakh, P. M.; Nazarenko, O. B.; Sarath Chandran, C.; Melnikova, T. V.; Nazarenko, S. Yu.; Kim, J.-C.

2017-07-01

The epoxy resins are widely used in nuclear and aerospace industries. The certain properties of epoxy resins as well as the resistance to radiation can be improved by the incorporation of different fillers. This study examines the effect of electron beam irradiation on the thermal and mechanical properties of the epoxy composites filled with aluminum nanoparticles at percentage of 0.35 wt%. The epoxy composites were exposed to the irradiation doses of 30, 100 and 300 kGy using electron beam generated by the linear electron accelerator ELU-4. The effects of the doses on thermal and mechanical properties of the aluminum based epoxy composites were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The results revealed that the studied epoxy composites showed good radiation resistance. The thermal and mechanical properties of the aluminum based epoxy composites increased with increasing the irradiation dose up to 100 kGy and decreased with further increasing the dose.

Impregnation of cinnamaldehyde into cassava starch biocomposite films using supercritical fluid technology for the development of food active packaging.

Science.gov (United States)

de Souza, Ana Cristina; Dias, Ana M A; Sousa, Hermínio C; Tadini, Carmen C

2014-02-15

In this work, supercritical solvent impregnation (SSI) has been tested for the incorporation of natural compounds into biocomposite materials for food packaging. Cinnamaldehyde, with proved antimicrobial activity against fungi commonly found in bread products, was successfully impregnated on biocomposite cassava starch based materials using supercritical carbon dioxide as solvent. Different process experimental conditions were tested (pressure, impregnation time and depressurization rate) at a fixed temperature (35 °C) in order to study their influence on the amount of impregnated cinnamaldehyde as well as on the morphology of the films. Results showed that all conditions permitted to impregnate antimicrobial active amounts superior to those previously obtained using conventional incorporation methods. Moreover, a significant decrease of the equilibrium water vapor sorption capacity and water vapor permeability of the films was observed after SSI processing which is a clear advantage of the process, considering the envisaged applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Design and analysis of MEMS MWCNT / epoxy strain sensor using ...

Indian Academy of Sciences (India)

Gaurav Sapra

2017-06-20

Jun 20, 2017 ... In this paper, highly sensitive MEMS-based multi- walled (MWCNT)/epoxy strain sensor has been designed using ... This paper also discusses the process flow for fabricating MWCNT/epoxy thin film ... stone bridge, i.e., connected to the gold metal pad of the sensor. The change in resistance with respect to.

Advanced light source vacuum policy and vacuum guidelines for beamlines and experiment endstations

International Nuclear Information System (INIS)

Hussain, Z.

1995-08-01

The purpose of this document is to: (1) Explain the ALS vacuum policy and specifications for beamlines and experiment endstations. (2) Provide guidelines related to ALS vacuum policy to assist in designing beamlines which are in accordance with ALS vacuum policy. This document supersedes LSBL-116. The Advanced Light Source is a third generation synchrotron radiation source whose beam lifetime depends on the quality of the vacuum in the storage ring and the connecting beamlines. The storage ring and most of the beamlines share a common vacuum and are operated under ultra-high-vacuum (UHV) conditions. All endstations and beamline equipment must be operated so as to avoid contamination of beamline components, and must include proper safeguards to protect the storage ring vacuum from an accidental break in the beamline or endstation vacuum systems. The primary gas load during operation is due to thermal desorption and electron/photon induced desorption of contaminants from the interior of the vacuum vessel and its components. The desorption rates are considerably higher for hydrocarbon contamination, thus considerable emphasis is placed on eliminating these sources of contaminants. All vacuum components in a beamline and endstation must meet the ALS vacuum specifications. The vacuum design of both beamlines and endstations must be approved by the ALS Beamline Review Committee (BRC) before vacuum connections to the storage ring are made. The vacuum design is first checked during the Beamline Design Review (BDR) held before construction of the beamline equipment begins. Any deviation from the ALS vacuum specifications must be approved by the BRC prior to installation of the equipment on the ALS floor. Any modification that is incorporated into a vacuum assembly without the written approval of the BRC is done at the user's risk and may lead to rejection of the whole assembly

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

OpenAIRE

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

2012-01-01

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

Improvement of the piezoelectric properties of glass fiber-reinforced epoxy composites by poling treatment

International Nuclear Information System (INIS)

Oh, S M; Hwang, H Y

2013-01-01

Recently, a new non-destructive method has been proposed for damage monitoring of glass fiber-reinforced polymer composite materials using the piezoelectric characteristics of a polymeric matrix. Several studies of the piezoelectric properties of unidirectional glass fiber epoxy composites and damage monitoring of double-cantilever beams have supported the claim that the piezoelectric method is feasible and powerful enough to monitor the damage of glass fiber epoxy composites. Generally, conventional piezoelectric materials have higher piezoelectric characteristics through poling treatment. In this work, we investigated the change of the piezoelectric properties of glass fiber-reinforced epoxy composites before and after poling treatment. The piezoelectric constants (d 33 ) of glass fiber-reinforced epoxy composites increased by more than 400%. Also, x-ray diffraction tests revealed that poling treatment changed the degree of crystallinity of the epoxy matrix, and this led to the improvement of the piezoelectric characteristics of glass fiber-reinforced epoxy composites. (paper)

Investigation of the Acoustic Properties of Chemically Impregnated Kayu Malam Wood Used for Musical Instrument

Directory of Open Access Journals (Sweden)

Md. Faruk Hossen

2018-01-01

Full Text Available The chemical modification or impregnation through preparing the wood polymer composites (WPCs can effectively reduce the hygroscopicity as well as can improve the acoustic properties of wood. On the other hand, a small amount of nanoclay into the chemical mixture can further improve the different properties of the WPCs through the preparation of wood polymer nanocomposites (WPNCs. Kayu Malam wood species with styrene (St, vinyl acetate (VA, and montmorillonite (MMT nanoclay were used for the preparation of WPNCs. The acoustic properties such as specific dynamic Young’s modulus (Ed/γ, internal friction (Q−1, and acoustic conversion efficiency (ACE of wood were examined using free-free flexural vibration. It was observed that the chemically impregnated wood composite showed a higher value of Ed/γ than raw wood and the nanoclay-loaded wood nanocomposite showed the highest value. The reverse trend was observed in the case of Q−1. On the other hand, chemical impregnation has a minor effect on ACE of wood for musical instruments. The results suggested that the chemically impregnated Kayu Malam wood polymer nanocomposite (WPNC is suitable for making soundboards of violin and guitar instruments to be played longer without losing tone quality.

UV curing silicon-containing epoxy resin and its glass cloth reinforced composites

International Nuclear Information System (INIS)

Yang Guang; Tang Zhuo; Huang Pengcheng

2007-01-01

A UV-curable cationic silicon-containing epoxy resin formulation was developed. The gel conversion of the cured resin after 10-min UV irradiation reached 80% in the presence of 5% diaryliodonium salt photoinitiator and 5.5% polyol chain transfer agent by cationic ring-opening polymerization. The glass cloth-reinforced composites were fabricated with the silicon-containing epoxy resin using the wet lay-up technique and UV irradiation. The mechanical properties of the composites were evaluated. Compared with glass cloth reinforced bisphenol A epoxy resin matrix composites, the silicon-containing epoxy resin matrix composites possessed higher tensile strength and interlayer shear strength which was 158.5MPa and 9.9MPa respectively while other mechanical properties such as flexural property and tensile modulus were similar. (authors)

Velocity Measurement of ultrasonic for evaluation of aging epoxy coating in containment structure of nuclear power plant

International Nuclear Information System (INIS)

Eun, Gil Soo; Kim, Noh Yu; Nah, Hwan Seon; Song, Young Chol

2001-01-01

Relative variation of ultrasonic velocity in aging epoxy coating in nuclear plant is measured for evaluation of the degradation of the epoxy coating. Time delay for ultrasound to travel through the epoxy film due to change of ultrasonic velocity is measured indirectly using ultrasonic interferometry which compares two reflection waves from the same point of coating surface at two different distances. Magnitude of the difference of two waves increases or decreases depending on change of the time of flight of ultrasound in the epoxy film caused by heat damage in the epoxy coating. Based on the transfer functions of the wedge and the epoxy coating in frequency domain, the reflection wave is analyzed and related to the velocity of ultrasound in the epoxy coating. A specially designed conical wedge is adopted to minimize the waviness effect of the surface of the epoxy coating. Epoxy films are fabricated, degraded under the accelerated aging conditions and tested to evaluate the change of ultrasonic velocity in the films. The experimental results show that the method can be applied to evaluate quantitatively the sealing quality of the epoxy coating.

Evaluation and Control of Thiol-ene/Thiol-epoxy Hybrid Networks.

Science.gov (United States)

Carioscia, Jacquelyn A; Stansbury, Jeffrey W; Bowman, Christopher N

2007-03-08

The development of thiol-ene/thiol-epoxy hybrid networks offers the advantage of tailorable polymerization kinetics while producing a highly crosslinked, high T(g) polymer that has significantly reduced shrinkage stress. Stoichiometric mixtures of pentaerythritol tetra(3-mercaptopropionate) (PETMP)/triallyl-1,3,5-triazine-2,4,6-trione (TATATO) (thiol-ene, mixture 1) and PETMP/bisphenol a diglycidyl ether (BADGE) (thiol-epoxy, mixture 2) were prepared and hybrid mixtures of 75/25, 50/50, 25/75, and 10/90 w/w of mixtures 1 and 2 were polymerized using a combination of both radical and anionic initiation. The light exposure timing and the relative initiation conditions of the two types were used to control the order and relative rates of the radical and anionic polymerizations. The 50/50 w/w thiol-ene/thiol-epoxy hybrid material exhibited a final stress of only 0.2 MPa, which is 90 % lower than the stress developed in a control dimethacrylate resin. Kinetic analysis indicates composition affects network development in thiol-ene/thiol-epoxy hybrid networks and produces materials with robust mechanical properties.

Syntheses and characterization of novel P/Si polysilsesquioxanes/epoxy nanocomposites

International Nuclear Information System (INIS)

Chiu Yiechan; Liu Fangyi; Ma, C.-C.M.; Chou, I.-C.; Riang Linawati; Chiang, C.-L.; Yang, J.-C.

2008-01-01

Phosphorus-containing polysilsesquioxane (PSSQ) was introduced into diglycidyl ether of bisphenol A epoxy (DGEBA) to generate a novel P/Si PSSQ nanocomposite. A series of nanocomposites was fabricated by changing the content of the 2-(diphenylphosphino)ethyltriethoxysilane (DPPETES) monomer or P/Si PSSQ cured with DGEBA epoxy and modified epoxy. The structure, thermal properties and flame-retardancy of the P/Si PSSQ nanocomposites were characterized by FT-IR, solid-state 29 Si NMR, thermogravimetric analysis (TGA) and limited oxygen index (LOI) instruments. The nano-sizes of the particles in P/Si PSSQ were approximately 30-50 nm, and the polarity of nanocomposites might generate the nanophase-separated structure from transmission electron microscopy (TEM). The urethane-like side group of the modified epoxy and the fabrication of oligomers in the curing reaction affected the T d5 values of nanocomposites. TGA and LOI results indicated that the char yield (29 wt%) increased and the nanocomposites were not very flammable (LOI = 30). The hybrid materials also exhibited high thermal stability, good flame-retardance and a lack of phase separation

Mechanical, Thermal, and Electrical Properties of Graphene-Epoxy Nanocomposites—A Review

Directory of Open Access Journals (Sweden)

Rasheed Atif

2016-08-01

Full Text Available Monolithic epoxy, because of its brittleness, cannot prevent crack propagation and is vulnerable to fracture. However, it is well established that when reinforced—especially by nano-fillers, such as metallic oxides, clays, carbon nanotubes, and other carbonaceous materials—its ability to withstand crack propagation is propitiously improved. Among various nano-fillers, graphene has recently been employed as reinforcement in epoxy to enhance the fracture related properties of the produced epoxy–graphene nanocomposites. In this review, mechanical, thermal, and electrical properties of graphene reinforced epoxy nanocomposites will be correlated with the topographical features, morphology, weight fraction, dispersion state, and surface functionalization of graphene. The factors in which contrasting results were reported in the literature are highlighted, such as the influence of graphene on the mechanical properties of epoxy nanocomposites. Furthermore, the challenges to achieving the desired performance of polymer nanocomposites are also suggested throughout the article.

Seawater infiltration effect on thermal degradation of fiber reinforced epoxy composites

Science.gov (United States)

Ibrahim, Mohd Haziq Izzuddin bin; Hassan, Mohamad Zaki bin; Ibrahim, Ikhwan; Rashidi, Ahmad Hadi Mohamed; Nor, Siti Fadzilah M.; Daud, Mohd Yusof Md

2018-05-01

Seawater salinity has been associated with the reduction of polymer structure durability. The aim of this study is to investigate the change in thermal degradation of fiber reinforced epoxy composite due to the presence of seawater. Carbon fiber, carbon/kevlar, fiberglass, and jute that reinforced with epoxy resin was laminated through hand-layup technique. Initially, these specimen was sectioned to 5×5 mm dimension, then immersed in seawater and distilled water at room temperature until it has thoroughly saturated. Following, the thermal degradation analysis using Differential Scanning Calorimetry (DSC), the thermic changes due to seawater infiltration was defined. The finding shows that moisture absorption reduces the glass transition temperature (Tg) of fiber reinforced epoxy composite. However, the glass transition temperature (Tg) of seawater infiltrated laminate composite is compareable with distilled water infiltrated laminate composite. The carbon fiber reinfored epoxy has the highest glass transition temperature out of all specimen.

Manufacturing and Shear Response Characterization of Carbon Nanofiber Modified CFRP Using the Out-of-Autoclave-Vacuum-Bag-Only Cure Process

Science.gov (United States)

McDonald, Erin E.; Wallace, Landon F.; Hickman, Gregory J. S.; Hsiao, Kuang-Ting

2014-01-01

The interlaminar shear response is studied for carbon nanofiber (CNF) modified out-of-autoclave-vacuum-bag-only (OOA-VBO) carbon fiber reinforced plastic (CFRP). Commercial OOA-VBO prepregs were coated with a CNF modified epoxy solution and a control epoxy solution without CNF to make CNF modified samples and control samples, respectively. Tensile testingwas used to study the in-plane shear performance of [±45°]4s composite laminates. Significant difference in failure modes between the control and CNF modified CFRPs was identified. The control samples experienced half-plane interlaminar delamination, whereas the CNF modified samples experienced a localized failure in the intralaminar region. Digital image correlation (DIC) surface strain results of the control sample showed no further surface strain increase along the delaminated section when the sample was further elongated prior to sample failure. On the other hand, the DIC results of the CNF modified sample showed that the surface strain increased relatively and uniformly across the CFRP as the sample was further elongated until sample failure. The failure mode evidence along with microscope pictures indicated that the CNF modification acted as a beneficial reinforcement inhibiting interlaminar delamination. PMID:24688435

Manufacturing and Shear Response Characterization of Carbon Nanofiber Modified CFRP Using the Out-of-Autoclave-Vacuum-Bag-Only Cure Process

Directory of Open Access Journals (Sweden)

Erin E. McDonald

2014-01-01

Full Text Available The interlaminar shear response is studied for carbon nanofiber (CNF modified out-of-autoclave-vacuum-bag-only (OOA-VBO carbon fiber reinforced plastic (CFRP. Commercial OOA-VBO prepregs were coated with a CNF modified epoxy solution and a control epoxy solution without CNF to make CNF modified samples and control samples, respectively. Tensile testingwas used to study the in-plane shear performance of [±45°]4s composite laminates. Significant difference in failure modes between the control and CNF modified CFRPs was identified. The control samples experienced half-plane interlaminar delamination, whereas the CNF modified samples experienced a localized failure in the intralaminar region. Digital image correlation (DIC surface strain results of the control sample showed no further surface strain increase along the delaminated section when the sample was further elongated prior to sample failure. On the other hand, the DIC results of the CNF modified sample showed that the surface strain increased relatively and uniformly across the CFRP as the sample was further elongated until sample failure. The failure mode evidence along with microscope pictures indicated that the CNF modification acted as a beneficial reinforcement inhibiting interlaminar delamination.

Manufacturing and shear response characterization of carbon nanofiber modified CFRP using the out-of-autoclave-vacuum-bag-only cure process.

Science.gov (United States)

McDonald, Erin E; Wallace, Landon F; Hickman, Gregory J S; Hsiao, Kuang-Ting

2014-01-01

The interlaminar shear response is studied for carbon nanofiber (CNF) modified out-of-autoclave-vacuum-bag-only (OOA-VBO) carbon fiber reinforced plastic (CFRP). Commercial OOA-VBO prepregs were coated with a CNF modified epoxy solution and a control epoxy solution without CNF to make CNF modified samples and control samples, respectively. Tensile testing was used to study the in-plane shear performance of [± 45°]4s composite laminates. Significant difference in failure modes between the control and CNF modified CFRPs was identified. The control samples experienced half-plane interlaminar delamination, whereas the CNF modified samples experienced a localized failure in the intralaminar region. Digital image correlation (DIC) surface strain results of the control sample showed no further surface strain increase along the delaminated section when the sample was further elongated prior to sample failure. On the other hand, the DIC results of the CNF modified sample showed that the surface strain increased relatively and uniformly across the CFRP as the sample was further elongated until sample failure. The failure mode evidence along with microscope pictures indicated that the CNF modification acted as a beneficial reinforcement inhibiting interlaminar delamination.

Interfacial Strength and Physical Properties of Functionalized Graphene - Epoxy Nanocomposites

Science.gov (United States)

Miller, Sandi G.; Heimann, Paula; Scheiman, Daniel; Adamson, Douglas H.; Aksay, Iihan A.; Prud'homme, Robert K.

2006-01-01

The toughness and coefficient of thermal expansion of a series of functionalized graphene sheet - epoxy nanocomposites are investigated. Functionalized graphene sheets are produced by splitting graphite oxide into single graphene sheets through a rapid thermal expansion process. These graphene sheets contain approx. 10% oxygen due to the presence of hydroxide, epoxide, and carboxyl functional groups which assist in chemical bond formation with the epoxy matrix. Intrinsic surface functionality is used to graft alkyl amine chains on the graphene sheets, and the addition of excess hardener insures covalent bonding between the epoxide matrix and graphene sheets. Considerable improvement in the epoxy dimensional stability is obtained. An increase in nanocomposite toughness is observed in some cases.

Characterization of impregnated GDC nano structures and their functionality in LSM based cathodes

DEFF Research Database (Denmark)

Klemensø, Trine; Chatzichristodoulou, Christodoulos; Nielsen, Jimmi

2012-01-01

Porous composite cathodes of LSM–YSZ (lanthanum strontium manganite and yttria stabilized zirconia) were impregnated with GDC (gadolinia doped ceria) nano particles. The impregnation process was varied using none or different surfactants (Triton X-45, Triton X-100, P123), and the quantity...... on the LSM phase and the LSM grain boundaries. The observations suggest that the improved performance associated with GDC nano particles is related to the particles placed near the TPB (triple phase boundary) zone. The GDC extends the TPB by creating an ionic conducting network on top of the LSM particles...

Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

Directory of Open Access Journals (Sweden)

Edith eMäder

2015-07-01

Full Text Available An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test.In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis.The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this

Evaluation of the plaque removal efficacy of xylitol-impregnated single-use toothbrush in vivo in 10-11-year-old children

Directory of Open Access Journals (Sweden)

Tezer Ulusu

2017-01-01

Full Text Available Objective: Xylitol is non-fermentable by oral bacteria and it inhibits the growth, metabolism and polysaccharide production of mutans streptococci, resulting in less bacterial plaque accumulation on teeth. This study aimed to compare the plaque removal efficacy on the teeth of children of xylitol-impregnated or non-impregnated single-use toothbrushes identical in shape and manufactured by the same company. Materials and Method: Thirty children aged 10-11 years were randomly separated into two groups of 15 children each. First group used a xylitol-impregnated toothbrush and the second group used a non-impregnated toothbrush for brushing. Dental plaque on upper central incisors was photographed intra-orally before and after brushing under standardized conditions. These photographs were stored in a computer and the amount of dental plaque was scored by using Turensky Modified Quinley Hein Plaque Index by a researcher blinded to the groups. Results: While both xylitol-impregnated and non-impregnated groups had significantly higher plaque index in before-brushing photographs than after-brushing photographs (p0.05. Conclusion: The results of the study emphasized that toothbrushing itself, regardless of xylitol content within the toothbrush, is essential for removing the dental plaque.

Controllable Impregnation Via Inkjet Printing for the Fabrication of Solid Oxide Cell Air Electrodes

KAUST Repository

Da'as, E. H.

2013-10-07

The impregnation method has been considered as one of the most successful techniques for the fabrication of highly efficient electrodes for solid oxide fuel and electrolysis cells (SOCs) at the lab scale. However, because the impregnation is usually performed manually, its irreproducibility remains a major problem that can be solved by using controllable techniques, such as inkjet printing. In this paper, lanthanum strontium manganite (LSM)/yttria stabilized zirconia (YSZ) air electrodes were prepared by infiltrating YSZ porous bodies with LSM precursor solution using inkjet printing, followed by annealing at 800°C for 2 hours. XRD analysis confirmed the formation of the LSM phase, which was in the form of nanoparticles with size in the 50-70 nm range on the YSZ walls, as revealed by FEG-SEM observations. The effect of printing parameters on the distribution of the impregnated phase was investigated and discussed.

Controllable Impregnation Via Inkjet Printing for the Fabrication of Solid Oxide Cell Air Electrodes

KAUST Repository

Da'as, E. H.; Irvine, J. T. S.; Traversa, Enrico; Boulfrad, S.

2013-01-01

The impregnation method has been considered as one of the most successful techniques for the fabrication of highly efficient electrodes for solid oxide fuel and electrolysis cells (SOCs) at the lab scale. However, because the impregnation is usually performed manually, its irreproducibility remains a major problem that can be solved by using controllable techniques, such as inkjet printing. In this paper, lanthanum strontium manganite (LSM)/yttria stabilized zirconia (YSZ) air electrodes were prepared by infiltrating YSZ porous bodies with LSM precursor solution using inkjet printing, followed by annealing at 800°C for 2 hours. XRD analysis confirmed the formation of the LSM phase, which was in the form of nanoparticles with size in the 50-70 nm range on the YSZ walls, as revealed by FEG-SEM observations. The effect of printing parameters on the distribution of the impregnated phase was investigated and discussed.

Mechanical properties of ramie fiber reinforced epoxy lamina composite for socket prosthesis

Directory of Open Access Journals (Sweden)

Tresna Soemardi

2010-10-01

Full Text Available This paper presents an investigation into the application of natural fiber composite especially ramie fiber reinforced epoxy lamina composite for socket prosthesis. The research focuses on the tensile and shear strength from ramie fiber reinforced epoxy lamina composite which will be applied as alternative material for socket prosthesis. The research based on American Society for Testing Material (ASTM standard D 3039/D 3039M for tensile strength and ASTM D 4255/D 4255M-83 for shear strength. The ramie fiber applied is a fiber continue 100 % Ne14'S with Epoxy Resin Bakelite EPR 174 as matrix and Epoxy Hardener V-140 as hardener. The sample composite test made by hand lay up method. Multiaxial characteristic from ramie fiber reinforced epoxy composite will be compared with ISO standard for plastic/polymer for health application and refers strength of material application at Prosthetics and Orthotics. The analysis was completed with the mode of the failure and the failure criterion observation by using Scanning Electron Microscope (SEM. Based on results of the research could be concluded that ramie fiber reinforced epoxy composite could be developed further as the alternative material for socket prosthesis on Vf 40-50%. Results of the research will be discussed in more detail in this paper.

Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

Science.gov (United States)

Alvarez Feijoo, Miguel Angel

2018-01-01

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (phase combination (PCM + epoxy resin + hardener + thickening agent) presents great potential as a heat-absorbing material at the temperatures employed. PMID:29373538

Synthesis and characterisation of epoxy resins reinforced with carbon nanotubes and nanofibers.

Science.gov (United States)

Prolongo, S G; Gude, M R; Ureña, A

2009-10-01

Epoxy nanocomposites were fabricated using two kinds of nanofiller, amino-functionalized multi-walled carbon nanotubes (CNTs) and non-treated long carbon nanofibers (CNFs). The non-cured mixtures were analysed through viscosity measurements. The effect of the nanoreinforcement on the curing process was determined by differential scanning calorimetry. Finally, the characterisation of cured nanocomposites was carried out studying their thermo-mechanical and electrical behaviour. At room temperature, the addition of CNTs causes a viscosity increase of epoxy monomer much more marked than the introduction of CNFs due to their higher specific area. It was probed that in that case exists chemical reaction between amino-functionalized CNTs and the oxirane rings of epoxy monomer. The presence of nanoreinforcement induces a decrease of curing reaction rate and modifies the epoxy conversion reached. The glass transition temperature of the nanocomposites decreases with the contents of CNTs and CNFs added, which could be related to plasticization phenomena of the nanoreinforcements. The storage modulus of epoxy resin significantly increases with the addition of CNTs and CNFs. This augment is higher with amino-functionalized CNTs due, between other reasons, to the stronger interaction with the epoxy matrix. The electrical conductivity is greatly increased with the addition of CNTs and CNFs. In fact, the percolation threshold is lower than 0.25 wt% due to the high aspect ratio of the used nanoreinforcements.

Adhesion of epoxy primer to hydrotalcite conversion coated AA2024

Science.gov (United States)

Leggat, Robert Benton, III

Hydrotalcite-based (HT) conversion coatings are being developed as an environmentally benign alternative to chromate conversion coatings (CCC). Accelerated exposure tests were conducted on epoxy primed, HT-modified AA2024 to gauge service performance. HT-based conversion coatings did not perform as well as the CCC when used with an epoxy primer. The current HT chemistries are optimized for stand-alone corrosion protection, however additional research into the primer/HT interactions is necessary before they can be implemented within a coating scheme. The relative contribution of mechanical and physico-chemical interactions in controlling adhesion has been investigated in this study. Practical adhesion tests were used to assess the dry and wet bond strength of epoxy primer on HT coatings using the pull-off tensile strength (POTS) as the figure of merit. The practical adhesion of HT coated samples generally fell between that observed for the CCC and bare AA2024. Laboratory testing was done to assess the physical and chemical properties of HT coatings. Contact angle measurements were performed using powders representative of different HT chemistries to evaluate the dispersive and acid-base character of the surface. The wet POTS correlated with the electrodynamic (dipole + dispersive) parameter of the surface tension. The HT surfaces were found to be predominantly basic. Given the basicity of epoxy, these results indicate that increasing the acidic character of HT coatings may increase the adhesion performance. This was supported by electrokinetic measurements in which the dry POTS was found to increase with decreasing conversion coating iso-electric point. The correlations with the dry and wet state adhesion are interpreted as indicating that dry state adhesion is optimized by minimizing unfavorable polar interactions between the basic epoxy and HT interfaces. Wet state adhesion, where polar interactions are disrupted, is dictated by non-polar bonding. FTIR

Pore structure modification of cement concretes by impregnation with sulfur-containing compounds