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Sample records for epoxy compounds

  1. Occupational skin diseases from epoxy compounds. Epoxy resin compounds, epoxy acrylates and 2,3-epoxypropyl trimethyl ammonium chloride.

    PubMed

    Jolanki, R

    1991-01-01

    Of a total of 3731 patients investigated between 1974 and 1990, 1844 (49.4%) had an occupational skin disease. Of them 142 (7.7%) had an occupational skin disease caused by epoxy compounds--135 patients (95%) had allergic contact dermatitis, five had irritant contact dermatitis, and two had contact urticaria. Apart from dermatoses, two patients had IgE-mediated asthma from exposure to DGEBA epoxy resins. Thus epoxy compounds are one of the main causes of occupational allergic contact dermatoses and can be considered potential causes of occupational asthma. The most frequent causes were epoxy resin compounds, which together induced 93% (132 cases) of all epoxy compound dermatoses. The three most common causative products were epoxy paints and their raw materials (31%, 41 cases), epoxy resin compounds used in electrical insulation (29%, 38 cases) and epoxy glues (18%, 24 cases). Fewer cases were caused by products containing epoxy acrylate and EPTMAC. The present study found that, in addition to contact allergy to DGEBA epoxy resins, contact allergy to epoxy hardeners, non-DGEBA resins and reactive diluents is common. Polyamine hardeners, most frequently MDA, DETA and TETA, rarely IPDA, tris-DMP, EDA, TMD and XDA, were the second commonest causes of contact allergy induced by epoxy resin compounds, after DGEBA epoxy resins. Cycloaliphatic epoxy resins and other non-DGEBA epoxy resins, including heterocyclic dimethyl hydantoin, phenol novolak and brominated epoxy resins, were the third commonest causes, and reactive diluents the fourth commonest cause of allergic dermatitis due to epoxy resin compounds. Most patients sensitized to reactive diluents were allergic to PGE, ortho-CGE, HDDGE and BDDGE, whereas fewer patients were sensitized to AGE, NPGDGE and BGE. Cross-sensitization between reactive diluents was common. Cardura E 10 and Epoxide 8 provoked no reactions. The present study also indicated that DGEBA epoxy resins with a high average MW ought to be regarded as

  2. Effects of polymer networks on physical properties of epoxy molding compounds

    SciTech Connect

    Eguchi, S.; Nagai, A.; Ishii, T.

    1996-10-01

    IC and LSI plastic packages are being changed from pin insertion to surface mounting types with increasing bit density. In their surface mounting technology, the most significant subject is preventing package cracks which occur when soldering temperatures are from 215 to 260{degrees}C. Effects of Polymer networks on physical properties of epoxy molding compounds are examined to improve the resistance to package cracks in the soldering process. Lowering the moisture absorption of compounds and increasing their adhesion are identified as effective methods. Since resins with a low moisture absorption and a high adhesion tend to have a low crosslinking density, the resin with a relatively low crosslinking density is chosen as a candidate for the encapsulating compound. The new epoxy molding compounds, while providing a high cohesive energy and a bulky structure inside the resin, can have a higher glass transition temperature in the relatively low crosslinking density.

  3. Radiation curing of epoxies

    NASA Astrophysics Data System (ADS)

    Dickson, Lawrence W.; Singh, Ajit

    The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

  4. Microautoradiography of Water-Soluble Compounds in Plant Tissue after Freeze-Drying and Pressure Infiltration with Epoxy Resin

    PubMed Central

    Vogelmann, Thomas C.; Dickson, Richard E.

    1982-01-01

    It is difficult to retain and localize radioactive, water-soluble compounds within plant cells. Existing techniques retain water-soluble compounds with varying rates of efficiency and are limited to processing only a few samples at one time. We developed a modified pressure infiltration technique for the preparation of microautoradiographs of 14C-labeled, water-soluble compounds in plant tissue. Samples from cottonwood (Populus deltoides Bartr. ex Marsh.) labeled with 14C were excised, quick frozen in liquid N2, freeze-dried at −50°C, and pressure-infiltrated with epoxy resin without intermediate solvents or prolonged incubation times. The technique facilitates the mass processing of samples for microautoradiography, gives good cellular retention of labeled water-soluble compounds, and is highly reproducible. Images Fig. 2 PMID:16662542

  5. Effect of vertical stacking dies on flow behavior of epoxy molding compound during encapsulation of stacked-chip scale packages

    NASA Astrophysics Data System (ADS)

    Khor, C. Y.; Abdullah, M. K.; Abdullah, M. Z.; Abdul Mujeebu, M.; Ramdan, D.; Majid, M. F. M. A.; Ariff, Z. M.

    2010-12-01

    This paper presents three dimensional (3D) simulation of flow visualization in the encapsulation of stacked-chip scales packages (S-CSP), using finite volume method. The S-CSP model is constructed using GAMBIT and simulated using FLUENT CFD software. The epoxy molding compound is Hitachi CEL-9200 XU (LF) and its flow is assumed laminar and incompressible. Cross viscosity model and volume of fluid technique are applied for flow front tracking of the encapsulant. The meshing is performed using tetrahedral elements and the discretization is done by first order upwind scheme. SIMPLE algorithm is selected for solving the governing equations. The top view and 3D view of simulation flow front profiles in the encapsulation process are presented. The percentage of filled volume versus filling time, viscosity versus shear rate and number of voids versus rows of stacked die are plotted. The temperature and pressure distributions within the mold cavity during the encapsulation process are also observed. Further, the possibility and cause of void formation during the encapsulation process are analyzed and discussed in detail. The number of vertical stacking dies and horizontal rows of packages are found to be crucial in the void formation. The numerical results are compared with previous experimental results and found in good conformity.

  6. Process for epoxy foam production

    DOEpatents

    Celina, Mathias C.

    2011-08-23

    An epoxy resin mixture with at least one epoxy resin of between approximately 60 wt % and 90 wt %, a maleic anhydride of between approximately 1 wt % and approximately 30 wt %, and an imidazole catalyst of less than approximately 2 wt % where the resin mixture is formed from at least one epoxy resin with a 1-30 wt % maleic anhydride compound and an imidazole catalyst at a temperature sufficient to keep the maleic anhydride compound molten, the resin mixture reacting to form a foaming resin which can then be cured at a temperature greater than 50.degree. C. to form an epoxy foam.

  7. Preparation and Characterization of a Novel Epoxy Molding Compound with Low Storage Modulus at High Temperature and Low Glass-Transition Temperature

    NASA Astrophysics Data System (ADS)

    Cui, Hui-wang; Li, Dong-sheng; Fan, Qiong

    2012-09-01

    Epoxy molding compound (EMC) has been widely used as a main material for encapsulation and protection of semiconductor packages because of its low cost, high moisture resistance, high heat resistance, and good mechanical performance. Due to the extensive application of lead-free solder in place of Sn-Pb, soldering temperature is higher than before; this demands that EMC, which is usually used for lead-free solder, should have extremely low thermal stress and excellent stability at elevated temperatures. In this work, 1,3-propanediol bis(4-aminobenzoate) (PBA) was added to an EMC product to form a novel epoxy molding compound (FEMC). PBA had very limited effect on the process feasibility of EMC, and caused reduction of the storage modulus by 40% to 50% at high temperatures and reduction of the glass-transition temperature by more than 10°C, which are very helpful to reduce thermal stress buildup during high-temperature soldering processes. The increases of the tab pull force of copper- and silver-plated lead frames within EMC due to PBA were up to 58% and 117%, respectively. With increasing PBA content in the EMC, water absorption increased in a linear fashion, so the amount of PBA added to the EMC should be limited, preferably to not more than 1%.

  8. Method of making thermally removable epoxies

    DOEpatents

    Loy, Douglas A.; Wheeler, David R.; Russick, Edward M.; McElhanon, James R.; Saunders, Randall S.

    2002-01-01

    A method of making a thermally-removable epoxy by mixing a bis(maleimide) compound to a monomeric furan compound containing an oxirane group to form a di-epoxy mixture and then adding a curing agent at temperatures from approximately room temperature to less than approximately 90.degree. C. to form a thermally-removable epoxy. The thermally-removable epoxy can be easily removed within approximately an hour by heating to temperatures greater than approximately 90.degree. C. in a polar solvent. The epoxy material can be used in protecting electronic components that may require subsequent removal of the solid material for component repair, modification or quality control.

  9. Epoxy hydantoins as matrix resins

    NASA Technical Reports Server (NTRS)

    Weiss, J.

    1983-01-01

    Tensile strength and fracture toughness of castings of the hydantoin resins cured with methylenedianiline are significantly higher than MY 720 control castings. Water absorption of an ethyl, amyl hydantoin formulation is 2.1 percent at equilibrium and Tg's are about 160 C, approximately 15 deg below the final cure temperature. Two series of urethane and ester-extended hydantoin epoxy resins were synthesized to determine the effect of crosslink density and functional groups on properties. Castings cured with methylenedianiline or with hexahydrophthalic anhydride were made from these compounds and evaluated. The glass transition temperatures, tensile strengths and moduli, and fracture toughness values were all much lower than that of the simple hydantoin epoxy resins. Using a methylene bishydantoin epoxy with a more rigid structure gave brittle, low-energy fractures, while a more flexible, ethoxy-extended hydantoin epoxy resin gave a very low Tg.

  10. Process for Preparing Epoxy-Reinforced Silica Aerogels

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B (Inventor)

    2016-01-01

    One-pot reaction process for preparing epoxy-reinforced monolithic silica aerogels comprising the reaction of at least one silicon compound selected from the group consisting of alkoxysilanes, orthosilicates and combination thereof in any ratio with effective amounts of an epoxy monomer and an aminoalkoxy silane to obtain an epoxy monomer-silica sol in solution, subsequently preparing an epoxy-monomer silica gel from said silica sol solution followed by initiating polymerization of the epoxy monomer to obtain the epoxy-reinforced monolithic silica aerogel.

  11. Stress Concentration in Glass-Epoxy Composite Plates.

    DTIC Science & Technology

    FIBER REINFORCED COMPOSITES, * GLASS REINFORCED PLASTICS, *STRESS CONCENTRATION, STRESS STRAIN RELATIONS, LOAD DISTRIBUTION, FIBERGLASS , MANUFACTURING, THESES, HOLES(OPENINGS), STRAIN GAGES, EPOXY COMPOUNDS, WEAR RESISTANCE.

  12. Fire-retardant epoxy polymers

    NASA Technical Reports Server (NTRS)

    Akawie, R. I.; Bilow, N.; Giants, T. W.

    1978-01-01

    Phosphorus atoms in molecular structure of epoxies make them fire-retardant without degrading their adhesive strength. Moreover, polymers are transparent, unlike compounds that contain arsenic or other inorganics. They have been used to bond polyvinylfluoride and polyether sulfone films onto polyimide glass laminates.

  13. Epoxy resin

    DOEpatents

    Wilson, Glenn R.; Salyer, Ival O.; Ball, III, George L.

    1976-07-13

    By mixing one part of a prepolymer containing a polyamine partially polymerized with an organic epoxide and subsequently reacted with a fatty acid containing from 8 to 32 carbon atoms, and then reacting this prepolymer mixture with 3 parts of an organic epoxide, a composition was obtained which made a gas frothable, shear-stable, room temperature curing, low density foam. A particularly advantageous prepolymer was prepared using a polyamine selected from the group consisting of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, partially polymerized with an organic epoxide having an average molecular weight of about 350 and having an epoxide equivalent of 185 to 192, and reacted with 2-10 weight percent linoleic acid. When one part of this prepolymer was reacted with about three parts of epoxy, and frothed by whipping in air or nitrogen an epoxy foam was produced which could be troweled onto surfaces and into corners or crevices, and subsequently cured, at near ambient temperature, to a strong dimensionally stable foam product.

  14. Flame Retardant Epoxy Resins

    NASA Technical Reports Server (NTRS)

    Thompson, C. M.; Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Lyon, R. E.

    2004-01-01

    As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

  15. Epoxy/Fluoroether Composites

    NASA Technical Reports Server (NTRS)

    Rosser, R. W.; Taylor, M. S.

    1986-01-01

    Composite materials made from unfilled and glass-fiber-reinforced epoxy toughened by copolymerization with elastomeric prepolymers of perfluoroalkyl ether diacyl fluoride (EDAF). Improved properties due to hydrogen bonding between rubber phase and epoxy matrix, plus formation of rubberlike phase domains that molecularly interpenetrate with epoxy matrix. With optimum rubber content, particle size, and particle shape, entire molecular structure reinforced and toughened. Improved composites also show increased failure strength, stiffness, glass-transition temperature, and resistance to water.

  16. Epoxy + liquid crystalline epoxy coreacted network

    NASA Astrophysics Data System (ADS)

    Punchaipetch, Prakaipetch

    2000-10-01

    Molecular reinforcement through in-situ polymerization of liquid crystalline epoxies (LCEs) and a non-liquid crystalline epoxy has been investigated. Three LCEs: diglycidyl ether of 4,4'-dihydroxybiphenol (DGE-DHBP) and digylcidyl ether of 4-hydroxyphenyl-4″-hydroxybiphenyl-4 '-carboxylate (DGE-HHC), were synthesized and blended with diglycidyl ether of bisphenol F (DGEBP-F) and subsequently cured with anhydride and amine curing agents. Curing kinetics were determined using differential scanning calorimetry (DSC). Parameters for autocatalytic curing kinetics of both pure monomers and blended systems were determined. The extent of cure for both monomers was monitored by using Fourier transform infrared spectroscopy (FT-IR). The glass transitions were evaluated as a function of composition using DSC and dynamic mechanical analysis (DMA). The results show that the LC constituent affects the curing kinetics of the epoxy resin and that the systems are highly miscible. The effects of molecular reinforcement of DGEBP-F by DGE-DHBP and DGE-HHC were investigated. The concentration of the liquid crystalline moiety affects mechanical properties. Tensile, impact and fracture toughness tests results are evaluated. Scanning electron microscopy of the fracture surfaces shows changes in failure mechanisms compared to the pure components. Results indicate that mechanical properties of the blended samples are improved already at low concentration by weight of the LCE added into epoxy resin. The improvement in mechanical properties was found to occur irrespective of the absence of liquid crystallinity in the blended networks. The mechanism of crack study indicates that crack deflection and crack bridging are the mechanisms in case of LC epoxy. In case of LC modified epoxy, the crack deflection is the main mechanism. Moreover, the effect of coreacting an epoxy with a reactive monomer liquid crystalline epoxy as a matrix for glass fiber composites was investigated. Mechanical

  17. Study of the relaxation behaviour of a tri-epoxy compound in the supercooled and glassy state by broadband dielectric spectroscopy

    NASA Astrophysics Data System (ADS)

    Pisignano, D.; Capaccioli, S.; Casalini, R.; Lucchesi, M.; Rolla, P. A.; Justl, A.; Rössler, E.

    2001-05-01

    The dynamics of the glass-forming tri-epoxy triphenylolmethane triglycidyl ether (TPMTGE) was investigated in the supercooled and glassy state by broadband dielectric spectroscopy. Measurements were performed in a frequency range between 10-2 Hz and 1010 Hz for temperatures in the range between 120 and 350 K. The dielectric response revealed the existence of two relaxation processes: the lower frequency one (α-relaxation) slows down very rapidly on cooling the system and leaves the experimental window on approaching the glass transition temperature Tg; the higher frequency one (β-relaxation) is observable both above and below Tg. The β-relaxation is comparatively quite fast, thus a large separation between the main and the secondary peaks is observed, and no complete merging of the α- and the β-process is found within the experimental window even at the highest temperatures. Besides, a third relaxation (β'), very weak indeed, was observed in the glassy state. The detailed analysis performed on the experimental data indicated that a single Vogel-Fulcher-Tamman equation well describes the change of the α-relaxation time in the entire temperature interval. In the same temperature range, the conductivity and the α-relaxation time are related to each other by a fractional Debye-Stokes-Einstein law. Moreover, our results confirmed the proportionality between the β-activation energy and the glass-transition temperature, which was found in other systems. As observed in previous experiments, both the shape parameters and the relaxation strength of β-relaxation are strongly affected by the transition from liquid to glassy state.

  18. Method for epoxy foam production using a liquid anhydride

    DOEpatents

    Celina, Mathias [Albuquerque, NM

    2012-06-05

    An epoxy resin mixture with at least one epoxy resin of between approximately 50 wt % and 100 wt %, an anhydride cure agent of between approximately 0 wt % and approximately 50 wt %, a tert-butoxycarbonyl anhydride foaming agent of between proximately 0.1-20 wt %, a surfactant and an imidazole or similar catalyst of less than approximately 2 wt %, where the resin mixture is formed from at least one epoxy resin with a 1-10 wt % tert-butoxycarbonyl anhydride compound and an imidazole catalyst at a temperature sufficient to keep the resin in a suitable viscosity range, the resin mixture reacting to form a foaming resin which in the presence of an epoxy curative can then be cured at a temperature greater than 50.degree. C. to form an epoxy foam.

  19. Rubberized, Brominated Epoxies

    NASA Technical Reports Server (NTRS)

    Gilwee, W.; Kourtides, D.; Parker, J.; Nir, Z.

    1985-01-01

    Graphite/epoxy composite materials made with resins containing bromine and rubber additives. New composites tougher and more resistant to fire. Flame resistance increased by introducing bromine via commercial brominated flame-retartant polymeric additives.

  20. 3,7,10,14,15-pentaacetyl-5-butanoyl-13,17-epoxy-8-myrsinene a novel compound isolated from Pycnocycla spinosa extract with potent anti-spasmodic and antidiarrheal properties

    PubMed Central

    Sadraei, H.; Ghanadian, M.; Asghari, G.; Sharifian, R.

    2015-01-01

    Bioassay monitoring of hydroalcoholic extract from the aerial part of Pyconcycla spinosa revealed that it contains components with spasmolytic activity in vitro. In addition, P. spinosa extract at oral dose of 1-5 mg/kg inhibits diarrhoea in animal models. Pharmacological screening of pure compounds isolated from P. spinosa hydroalcoholic extract led to the identification of 3,7,10,14,15-pentaacetyl-5-butanoyl-13,17-epoxy-8-myrsinene (PABEM) which is a new diterpene. In this research, we have investigated antispasmodic and antidiarrheal effects of PABEM for comparison with P. spinosa extract. Aerial parts of P. spinosa were extracted with ethanol. For antispasmodic studies, rat isolated ileum was suspended in Tyrode's solution in an organ bath. The ileum was contracted by acetylcholine (ACh, 0.5 μM), serotonin (5-HT, 5 μM) or electrical field stimulation (EFS). P. spinosa extract in a concentration dependent manner (10-640 μg/ml) inhibited ileum contractions induced by ACh, 5-HT or EFS. The new compound isolated form P. spinosa extract “PABEM” in a similar manner inhibited the contractile response to ACh, 5-HT and EFS. However, the inhibitory effects of PABEM were observed at much lower bath concentrations. The relaxation effect of PABEM was started at 40 ng/ml bath concentration and with 2.5 μg/ml PABEM in the bath, the contractile responses of ileum were completely abolished. Both hydroalcoholic extract of P. spinosa and PABEM reduced intestinal meal transit and castor oil and MgSO4 induced diarrhoea in mice. However, PABEM was about 10 times more potent than its parent extract. This research shows that PABEM is probably the main component responsible for antispasmodic and antidiarrheal actions of P. spinosa extract. PMID:26430457

  1. Imide Modified Epoxy Matrix Resin.

    DTIC Science & Technology

    1981-02-01

    the bisimide amine cured epoxies (IME’s) were considerably lower than the state-of-the-art epoxies . The strain-to-failure of the control resin system ...nine epoxy resin systems which were prepared from tetraglycidyl methylenedianiline (MY 720) cured with a stoichiometric quantity of bisimide-amine and...graphite imide modified cured epoxy resin composites. The designation for each material is also listed in Table 1. The composition of each resin system

  2. Cobalt ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1983-01-01

    Varying concentrations of an organometallic cobalt complex were added to an epoxy system currently used by the aerospace industry as a composite matrix resin. Methods for combining cobalt (III) acetylacetonate with a tetraglycidyl 4,4 prime - diaminodiphenylmethane-based epoxy were investigated. The effects of increasing cobalt ion concentration on the epoxy cure were demonstrated by epoxy gel times and differential scanning calorimetry cure exotherms. Analysis on cured cobalt-containing epoxy castings included determination of glass transition temperatures by thermomechanical analysis, thermooxidative stabilities by thermogravimetric analysis, and densities in a density gradient column. Flexural strength and stiffness were also measured on the neat resin castings.

  3. An investigation of chemically-induced improvement in saturation moisture characteristics of epoxies

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; St.clair, T. L.; Stoakley, D. M.

    1984-01-01

    MY-720/DDS epoxy samples were treated with three selected chemical compounds to render the active H-sites inactive for moisture absorption. Treating the epoxy castings with acetyl chloride and dichlorodimethyl silane leads only to surface changes indicating that these molecules are too large to penetrate the epoxy castings. Boron trifluoride, on the other hand, does penetrate the epoxy chain as is indicated by the formation of green domains in the interior of the castings. However, the process of saturating the specimens with moisture appears to leach out the chemical additives--thereby nullifying their possible ameliorative effects.

  4. Compound

    NASA Astrophysics Data System (ADS)

    Suzumura, Akitoshi; Watanabe, Masaki; Nagasako, Naoyuki; Asahi, Ryoji

    2014-06-01

    Recently, Cu-based chalcogenides such as Cu3SbSe4, Cu2Se, and Cu2SnSe3 have attracted much attention because of their high thermoelectric performance and their common feature of very low thermal conductivity. However, for practical use, materials without toxic elements such as selenium are preferable. In this paper, we report Se-free Cu3SbS4 thermoelectric material and improvement of its figure of merit ( ZT) by chemical substitutions. Substitutions of 3 at.% Ag for Cu and 2 at.% Ge for Sb lead to significant reductions in the thermal conductivity by 37% and 22%, respectively. These substitutions do not sacrifice the power factor, thus resulting in enhancement of the ZT value. The sensitivity of the thermal conductivity to chemical substitutions in these compounds is discussed in terms of the calculated phonon dispersion and previously proposed models for Cu-based chalcogenides. To improve the power factor, we optimize the hole carrier concentration by substitution of Ge for Sb, achieving a power factor of 16 μW/cm K2 at 573 K, which is better than the best reported for Se-based Cu3SbSe4 compounds.

  5. Bio-Based Aromatic Epoxy Monomers for Thermoset Materials.

    PubMed

    Ng, Feifei; Couture, Guillaume; Philippe, Coralie; Boutevin, Bernard; Caillol, Sylvain

    2017-01-18

    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.

  6. Metal ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1982-01-01

    A variety of metallic and organometallic complexes to be used as potential additives for an epoxy used by the aerospace industry as a composite matrix resin were investigated. A total of 9 complexes were screened for compatibility and for their ability to accelerate or inhibit the cure of a highly crosslinkable epoxy resin. Methods for combining the metallic complexes with the resin were investigated, gel times recorded, and cure exotherms studied by differential scanning calorimetry. Glass transition temperatures of cured metal ion containing epoxy castings were determined by thermomechanical analysis. Thermal stabilities of the castings were determined by thermogravimetric analysis. Mechanical strength and stiffness of these doped epoxies were also measured.

  7. Finite-element analysis of an epoxy-curing process

    SciTech Connect

    Gartling, D K; Hickox, C E; Nunziato, J W

    1983-01-01

    A finite element numerical procedure is used to study the curing of an epoxy compound. The problem involves the gelation of an incompressible liquid due to an exothermic chemical reaction. Nonuniform temperature fields produce buoyancy-driven fluid motions that interact with the solidifying material. The numerical simulations provide temperature histories and the progression of the gel front that are compared with experimental data.

  8. Interaction of water with epoxy.

    SciTech Connect

    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.

  9. Imide modified epoxy matrix resins

    NASA Technical Reports Server (NTRS)

    Scola, D. A.; Pater, R. H.

    1981-01-01

    High char yield epoxy using novel bisimide amines (BIA's) as curing agents with a state of the art epoxy resin was developed. Stoichiometric quantities of the epoxy resin and the BIA's were studied to determine the cure cycle required for preparation of resin specimens. The bisimide cured epoxies were designated IME's (imide modified epoxy). The physical, thermal and mechanical properties of these novel resins were determined. The levels of moisture absorption exhibited by the bisimide amine cured expoxies (IME's) were considerably lower than the state of the art epoxies. The strain-to-failure of the control resin system was improved 25% by replacement of DDS with 6F-DDS. Each BIA containing resin exhibited twice the char yield of the control resin MY 720/DDS. Graphite fiber reinforced control (C) and IME resins were fabricated and characterized. Two of the composite systems showed superior properties compared to the other Celion 6000/IME composite systems and state of the art graphite epoxy systems. The two systems exhibited excellent wet shear and flexural strengths and moduli at 300 and 350 F.

  10. Thermophysical and flammability characterization of phosphorylated epoxy adhesives

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Parker, J. A.; Giants, T. W.; Bilow, N.; Hsu, M.-T.

    1980-01-01

    Some of the thermophysical and flammability properties of a phosphorylated epoxy adhesive, which has potential applications in aircraft interior panels, are described. The adhesive consists of stoichiometric ratios of bis(3-glycidyloxphenyl)methylphosphine oxide and bis(3-aminophenyl)methylphosphine oxide containing approximately 7.5% phosphorus. Preliminary data are presented from adhesive bonding studies conducted utilizing this adhesive with polyvinyl fluoride (PVF) film and phenolic-glass laminates. Limiting oxygen index and smoke density data are presented and compared with those of the tetraglycidyl methylene dianiline epoxy resin-adhesive system currently used in aircraft interiors. Initial results indicate that the phosphorylated epoxy compound has excellent adhesive properties when used with PVF film and that desirable fire-resistant properties are maintained.

  11. New energetic epoxy binders

    SciTech Connect

    Jain, S.R.; Amanulla, S.

    1996-07-01

    A new class of epoxy resins having N{single_bond}N bonds in the backbone has been synthesized with a view to explore their properties as energetic binders. The N-epoxidation of bis-dicarbonylhydrazones of adipic, azelaic and sebacic dihydrazides results in the formation of viscous resins having epoxide end groups. The resins have been characterized by the elemental and end group analyses, IR and NMR spectra. Relevant properties for their use as binders in solid propellants, such as thermal stability, heat of combustion, burn rate and performance parameters of AP-based propellant systems, have been evaluated. A significant increase in the burn rate of AP-based propellants noticed, is perhaps related to the exothermicity of the binder decomposition and the reactivity of N{single_bond}N bonds with perchloric acid formed during the combustion of AP.

  12. Synthesis of polyoxometalate-loaded epoxy composites

    DOEpatents

    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.

  13. A study of friction wear behaviour of nano-ferite modified epoxy resins

    NASA Astrophysics Data System (ADS)

    Munteniţă, C.; Eni, C.; Graur, I.; Ungureanu, C.; Bodor, M.

    2017-02-01

    Ferrites are generally used to obtain soft magnets for domestic or industrial applications but their use in this direction had generated an increasing interest in modifying the polymer properties by dispersing in their volume certain amounts of these ceramic compounds. The current study focused friction wear behaviour induced by the presence of nano-sized strontium ferrite and barium ferrite in an epoxy matrix. The wear behaviour of nanoferite modified epoxy resins tests were conducted on a pin-on-disc geometry. Three types of epoxy resins had been used with 5% weight ratio of each type of ferrite and 10% weight ratio when both ferrites were used.

  14. Multifunctional epoxy composites with natural Moroccan clays

    NASA Astrophysics Data System (ADS)

    Monsif, M.; Zerouale, A.; Kandri, N. Idrissi; Allali, F.; Sgarbossa, P.; Bartolozzi, A.; Tamburini, S.; Bertani, R.

    2016-05-01

    Two natural Moroccan clays, here firstly completely characterized, have been used as fillers without modification in epoxy composites. Mechanical properties resulted to be improved and a significant antibacterial activity is exhibited by the epoxy composite containing the C2 clay.

  15. Epoxy resin monomers with reduced skin sensitizing potency.

    PubMed

    O'Boyle, Niamh M; Niklasson, Ida B; Tehrani-Bagha, Ali R; Delaine, Tamara; Holmberg, Krister; Luthman, Kristina; Karlberg, Ann-Therese

    2014-06-16

    Epoxy resin monomers (ERMs), especially diglycidyl ethers of bisphenol A and F (DGEBA and DGEBF), are extensively used as building blocks for thermosetting polymers. However, they are known to commonly cause skin allergy. This research describes a number of alternative ERMs, designed with the aim of reducing the skin sensitizing potency while maintaining the ability to form thermosetting polymers. The compounds were designed, synthesized, and assessed for sensitizing potency using the in vivo murine local lymph node assay (LLNA). All six epoxy resin monomers had decreased sensitizing potencies compared to those of DGEBA and DGEBF. With respect to the LLNA EC3 value, the best of the alternative monomers had a value approximately 2.5 times higher than those of DGEBA and DGEBF. The diepoxides were reacted with triethylenetetramine, and the polymers formed were tested for technical applicability using thermogravimetric analysis and differential scanning calorimetry. Four out of the six alternative ERMs gave polymers with a thermal stability comparable to that obtained with DGEBA and DGEBF. The use of improved epoxy resin monomers with less skin sensitizing effects is a direct way to tackle the problem of contact allergy to epoxy resin systems, particularly in occupational settings, resulting in a reduction in the incidence of allergic contact dermatitis.

  16. 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.

    PubMed

    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.

  17. Fire-Retardant Epoxy Adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.

    1982-01-01

    Phosphorus-containing epoxy is fire-retardant and translucent. Intended as adhesive for laminated plastic sheets, new material bonds well to titanium dioxide-filled plastic film, which ordinarily shows little surface interaction with adhesives. Fire retardancy has been demonstrated, and smoke density is low enough to avoid smoke obscuration.

  18. Epoxy Grout With Silica Thickener

    NASA Technical Reports Server (NTRS)

    Mcclung, C. E.

    1984-01-01

    Grout cures quickly, even in presence of hydraulic oil. Grout is mixture of aggregate particles, finely-divided silica, epoxy resin, and triethylenetetramine curing agent, with mixture containing about 85 percent silica and aggregate particle sand 15 percent resin and curing agent. Silica is thickening agent and keeps grout from sagging.

  19. Shelf Stable Epoxy Repair Adhesive

    DTIC Science & Technology

    2015-02-01

    Epoxy Resin Adhesive WP-1763 viii FINAL REPORT List of Acronyms ACN Acetonitrile ASTM American Society for Testing and Materials BPA Bisphenol...the oven and immediately cooled to room temperature. Approximately 1.0 mL of acetonitrile ( ACN ) was added to each vial using a glass syringe. The

  20. Hearing loss in workers exposed to epoxy adhesives and noise: a cross-sectional study

    PubMed Central

    Yang, Hsiao-Yu; Shie, Ruei-Hao; Chen, Pau-Chung

    2016-01-01

    Objectives Epoxy adhesives contain organic solvents and are widely used in industry. The hazardous effects of epoxy adhesives remain unclear. The objective of this study was to investigate the risk of hearing loss among workers exposed to epoxy adhesives and noise. Design Cross-sectional study. Methods For this cross-sectional study, we recruited 182 stone workers who were exposed to both epoxy adhesives and noise, 89 stone workers who were exposed to noise only, and 43 workers from the administrative staff who had not been exposed to adhesives or noise. We obtained demographic data, occupational history and medical history through face-to-face interviews and arranged physical examinations and pure-tone audiometric tests. We also conducted walk-through surveys in the stone industry. A total of 40 representative noise assessments were conducted in 15 workplaces. Air sampling was conducted at 40 workplaces, and volatile organic compounds were analysed using the Environmental Protection Agency (EPA) TO-15 method. Results The mean sound pressure level was 87.7 dBA (SD 9.9). The prevalence of noise-induced hearing loss was considerably increased in the stone workers exposed to epoxy adhesives (42%) compared with the stone workers who were not exposed to epoxy adhesives (21%) and the administrative staff group (9.3%). A multivariate logistic regression analysis revealed that exposure to epoxy adhesives significantly increased the risk of hearing loss between 2 and 6 kHz after adjusting for age. Significant interactions between epoxy adhesives and noise and hearing impairment were observed at 3, 4 and 6 kHz. Conclusions Epoxy adhesives exacerbate hearing impairment in noisy environments, with the main impacts occurring in the middle and high frequencies. PMID:26892792

  1. Allergic contact dermatitis from a nonbisphenol A epoxy in a graphite fiber reinforced epoxy laminate.

    PubMed

    Mathias, C G

    1987-09-01

    An employee of the Composites Division of an aircraft engine manufacturing firm developed dermatitis associated with the handling of a graphite fiber reinforced epoxy laminate (epoxy prepreg). Patch test investigation demonstrated that the responsible causal agent was the nonbisphenol A epoxy binder, 4-glycidyloxy-N, N-diglycidylaniline. A patch test with bisphenol A epoxy from a standard patch test screening series was negative. Subsequent interviews with employees of the Composites Division suggested that a relative lack of awareness of the cutaneous hazards of fiber reinforced epoxy laminates, compared with liquid epoxy resin systems, may be an important risk factor for allergic sensitization to these composite materials.

  2. Preparation and cured properties of novel cycloaliphatic epoxy resins

    SciTech Connect

    Tokizawa, Makoto; Okada, Hiroyoshi; Wakabayashi, Nobukatsu; Kimura, Tomiaki . Research Center)

    1993-10-20

    Preparation and characterization of novel cycloaliphatic epoxy resins, which are derived from octadienyl compounds, were studied. From a model peracetic acid epoxidation reaction using 2,7-octadienyl acetate-1, the structure of the liquid resins is estimated to be mainly terminal epoxides and some amount of inner epoxide depending on the epoxide content. The epoxy resins offer lower toxicity and lower vapor pressure. The reactivity of the resin with acid anhydrides is moderate but faster than that of traditional cyclohexane epoxide-type resins and slower than that of the glycidyl ester-type resins. This reactivity was also examined using model compounds. The heat deflection temperature of the hexahydro-phthalic anhydride-cured resins is shown to be directly proportional to the number of epoxy groups in the molecules. The flexural strength of the cured resins is nearly equivalent to that of the commercial resins, although the flexural elongation of the resins is larger than that of the rigid cyclohexane epoxide-type resins. The thermal stability of the cured resins is compared to typical rigid cycloaliphatic resins; furthermore, high water resistance of the cured resins is suggested to be attributed to the hydrophobic character of the C[sub 8] chain by cross-linking.

  3. Characterization of Hybrid Epoxy Nanocomposites

    PubMed Central

    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.

  4. EPOXI Trajectory and Maneuver Analyses

    NASA Technical Reports Server (NTRS)

    Chung, Min-Kun J.; Bhaskaran, Shyamkumar; Chesley, Steven R.; Halsell, C. Allen; Helfrich, Clifford E.; Jefferson, David C.; McElrath, Timothy P.; Rush, Brian P.; Wang, Tseng-Chan M.; Yen, Chen-wan L.

    2011-01-01

    The EPOXI mission is a NASA Discovery Mission of Opportunity combining two separate investigations: Extrasolar Planet Observation and Characterization (EPOCh) and Deep Impact eXtended Investigation (DIXI). Both investigations reused the DI instruments and spacecraft that successfully flew by the comet Tempel-1 (4 July 2005). For EPOCh, the goal was to find exoplanets with the high resolution imager, while for DIXI it was to fly by the comet Hartley 2 (4 Nov 2010). This paper documents the navigation experience of the earlier ma-neuver analyses critical for the EPOXI mission including statistical ?V analyses and other useful analyses in designing maneuvers. It also recounts the trajectory design leading up to the final reference trajectory to Hartley 2.

  5. Evaluation of experimental epoxy monomers

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; St.clair, T. L.; Pratt, J. R.; Ficklin, R.

    1985-01-01

    Future generation aircraft need higher performance polymer matrices to fully achieve the weight savings possible with composite materials. New resins are being formulated in an effort to understand basic polymer behavior and to develop improved resins. Some polymer/curing agent combinations that could be useful are difficult to process. In the area of epoxies, a major problem is that some components have physical properties which make them difficult to utilize as matrix resins. A previous study showed that the use of ultrasonic energy can be advantageous in the mixing of curing agents into a standard epoxy resin, such as MY 720 (Ciba-Geigy designation). This work is expanded to include three novel epoxides.

  6. Imide modified epoxy matrix resins

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1982-01-01

    Results of a program designed to develop tough imide modified epoxy (IME) resins cured by bisimide amine (BIA) hardeners are presented. State of the art epoxy resin, MY720, was used. Three aromatic bisimide amines and one aromatic aliphatic BIA were evaluated. BIA's derived from 6F anhydride (3,3 prime 4,4 prime-(hexafluoro isopropyl idene) bis (phthalic anhydride) and diamines, 3,3 prime-diam nodiphenyl sulfone (3,3 prime-DDS), 4,4 prime-diamino diphenyl sulfone (4,4 prime-DDS), 1.12-dodecane diamine (1,12-DDA) were used. BIA's were abbreviated 6F-3,3 prime-DDS, 6F-4,4 prime-DDS, 6F-3,3 prime-DDS-4,4 prime DDS, and 6F-3,3 prime-DDS-1,12-DDA corresponding to 6F anhydride and diamines mentioned. Epoxy resin and BIA's (MY720/6F-3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA and a 50:50 mixture of a BIA and parent diamine, MY720/6F-3,3 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-4,4 prime-DDS/3,3 prime-DDS, MY720/6F-3,3 prime-DDS-1,12-DDA/3,3 prime-DDS were studied to determine effect of structure and composition. Effect of the addition of two commercial epoxies, glyamine 200 and glyamine 100 on the properties of several formulations was evaluated. Bisimide amine cured epoxies were designated IME's (imide modified epoxy). Physical, thermal and mechanical properties of these resins were determined. Moisture absorption in boiling water exhibited by several of the IME's was considerably lower than the state of the art epoxies (from 3.2% for the control and state of the art to 2.0 wt% moisture absorption). Char yields are increased from 20% for control and state of the art epoxies to 40% for IME resins. Relative toughness characteristics of IME resins were measured by 10 deg off axis tensile tests of Celion 6000/IME composites. Results show that IME's containing 6F-3,3 prime-DDS or 6F-3,3 prime-DDS-1,12-DDA improved the "toughness" characteristics of composites by about 35% (tensile strength), about 35% (intralaminar shear

  7. Flammability of Epoxy Resins Containing Phosphorus

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.; Thompson, C. M.; Smith, J. G.; Connell, J. W.; Hinkley, J. A.

    2005-01-01

    As part of a program to develop fire-resistant exterior composite structures for future subsonic commercial and general aviation aircraft, flame-retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured neat epoxy formulations were characterized by thermogravimetric analysis, propane torch test, elemental analysis, microscale combustion calorimetry, and fire calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness and compressive strength of several cured formulations showed no detrimental effect due to phosphorus content. The chemistry and properties of these new epoxy formulations are discussed.

  8. Epoxy resins in the construction industry.

    PubMed

    Spee, Ton; Van Duivenbooden, Cor; Terwoert, Jeroen

    2006-09-01

    Epoxy resins are used as coatings, adhesives, and in wood and concrete repair. However, epoxy resins can be highly irritating to the skin and are strong sensitizers. Some hardeners are carcinogenic. Based on the results of earlier Dutch studies, an international project on "best practices,"--Epoxy Code--with epoxy products was started. Partners were from Denmark, Germany, the Netherlands, and the UK. The "Code" deals with substitution, safe working procedures, safer tools, and skin protection. The feasibility of an internationally agreed "ranking system" for the health risks of epoxy products was studied. Such a ranking system should inform the user of the harmfulness of different epoxies and stimulate research on less harmful products by product developers.

  9. High char imide-modified epoxy matrix resins. [for graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D.

    1979-01-01

    The synthesis of a class of bis(imide-amine) curing agents for epoxy matrix resins is discussed. Glass transition temperatures and char yield data of an epoxy cured with various bis(imide-amines) are presented. The room temperature and 350 F mechanical properties, and char yields of unidirectional graphite fiber laminates prepared with conventional epoxy and imide-modified epoxy resins are presented.

  10. Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

    PubMed

    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.

  11. Influence of reaction condition on viscosity of polyurethane modified epoxy based on glycerol monooleate

    NASA Astrophysics Data System (ADS)

    Triwulandari, Evi; Ramadhan, Mohammad Kemilau; Ghozali, Muhammad

    2017-01-01

    Polyurethane modified epoxy based on glycerol monooleate (PME-GMO) was synthesized. GMO as polyol for synthesis of PME-GMO was synthesized via Fisher Esterification between oleic acid from palm oil and glycerol by using sulfuric acid as catalyst with time variation i.e. 3, 4, 5 and 6 hours at 160°C. Characterizations of GMO were carried out by analysis of acid number, hydroxyl value and FTIR. The data show that the conversion of oleic acid to ester compound is directly proportional with the increasing of reaction time but the enhancement is not significant after 3 hours. Furthermore, GMO product was used as polyol for modification of epoxy with polyurethane. Modification of epoxy with polyurethane was performed by reacted epoxy, tolonate and GMO simultaneously in one step. In this research, the reaction condition was varied i.e. time reaction (0.5; 1; 1.5; 2; 2.5 hours), composition of polyurethane used (10%, 20% toward epoxy) and rasio of tolonate and GMO (NCO/OH ratio) as component of polyurethane (1.5 and 2.5). Characterization of polyurethane modified epoxy based on glycerol (PME-GMO) was conducted by viscosity and FTIR analysis. The viscosity of PME-GMO increased with increasing of reaction time, polyurethane composition and NCO/OH ratio.

  12. Nonmetallic materials handbook. Volume 1: Epoxy materials

    NASA Technical Reports Server (NTRS)

    Podlaseck, S. E.

    1979-01-01

    Thermochemical and other properties data is presented for the following types of epoxy materials: adhesives, coatings finishes, inks, electrical insulation, encapsulants, sealants, composite laminates, tapes, and thermal insulators.

  13. Treatment of high-latency microcapsules containing an aluminium complex with an epoxy-functionalised trialkoxysilane.

    PubMed

    Kamiya, Kazunobu; Suzuki, Noboru

    2016-12-01

    Some aluminium complexes are excellent catalysts of cationic polymerisation and are used for low-temperature and fast-curing adhesive, used in electronic part mounting. Microencapsulation is a suitable technique for getting high latency of the catalysts and long shelf life of the adhesives. For the higher latency in a cycloaliphatic epoxy compound, the microcapsule surface which retained small amount of aluminium complex was coated with epoxy polymer and the effect was examined. From the X-ray photoelectron spectroscopic results, the surface was recognised to be sufficiently coated and the differential scanning calorimetric analyses showed that the coating did not significantly affect the low-temperature and fast-curing properties of adhesive. After storing the mixture of cycloaliphatic epoxy compound, coated microcapsules, triphenylsilanol and silane coupling agent for 48 h at room temperature, the increase in viscosity was only 0.01 Pa s, resulting in the excellent shelf life.

  14. Comparative properties of optically clear epoxy encapsulants

    NASA Astrophysics Data System (ADS)

    Edwards, Maury; Zhou, Yan

    2001-12-01

    Three epoxy systems were evaluated for physical dn optical properties. The three systems chosen for the study were selected on the basis of their optical clarity, color and chemistry. Three distinctly different chemistries were chosen, aromatic epoxy-amine cured. Aromatic epoxy- anhydride cured and cycloaliphatic epoxy-anhydride cured. All three systems remained optically clear and water-white after full cure. The three selected systems were tested for physical properties, adhesion and light transmission properties. Light transmission was measured after thermal and humidity exposure. Adhesion was measured after humidity exposure only. Both of the epoxy-anhydride systems performed well in optical properties but poorer in adhesion as compared to the epoxy-amine system. The aromatic epoxy- amine system discolored badly during thermal exposure at 100 C. Data generated from this work will be used in selecting clear encapsulating materials for photonics applications. No single system offers optimal performance in all areas. The best compromise material is the aromatic epoxy-anhydride system.

  15. Thermoset epoxy polymers from renewable resources

    DOEpatents

    East, Anthony; Jaffe, Michael; Zhang, Yi; Catalani, Luiz H

    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.

  16. Curing of Graphite/Epoxy Composites.

    DTIC Science & Technology

    1983-03-01

    365-371 (1973). 21. Pappalardo , L. T., "DSC Evaluation of B-Stage Epoxy-Glass Prepregs For Multilayer Boards," SPE Technical Papers, 20, 13-16 (1974...Kamal, M. R., "Differential Scanning Calorimetry of Epoxy Cure: Isothermal Cure Kinetics," Thermochimica Acta, 14, 41-59 (1976). 24. Pappalardo , L. T

  17. Magnetic Resonance Determinations of Structure and Reaction Kinetics of Epoxy/Amine Systems.

    DTIC Science & Technology

    1981-12-31

    bisphenol A ( DGEBA ), and two model compounds, a secondary amine nitroxide and a tertiary amine nitroxide. The rate constants for both reactions (kl, k2...EPR EXPERIMENTS ON EPOXY RESINS ....................................... 4 2.1 Nitroxide- DGEBA Kinetics ......................................... 4 2.2...dependence of the rate constants for METAMIN and DIMETAMIN reactions with DGEBA ...................................... 14 11. EPR spectra observed at 299

  18. EPOXI at Comet Hartley 2

    NASA Technical Reports Server (NTRS)

    A'Hearn, Michael F.; Belton, Michael J. S.; Delamere, W. Alan; Feaga, Lori M.; Hampton, Donald; Kissel, Jochen; Klaasen, Kenneth P.; McFadden, Jessica M.; Meech, Karen J.; Melosh, H. Jay; Schultz, Peter H.; Sunshine, Jessica M.; Thomas, Peter C.; Veverka, Joseph; Wellnitz, Dennis D.; Yeomans, Donald K.; Besse, Sebastien; Bodewits, Dennis; Bowling, Timothy J.; Carcish, Brian T.; Collins, Steven M.; Farnham, Tony F.; Groussin, Oliver; Hermalyn, Brendan; Kelley, Michael S.

    2011-01-01

    Understanding how comets work, i,e., what drives their activity, is crucial to using comets to study the early solar system. EPOXI flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus. taking both images and spectra. Unlike large, relatively inactive nuclei, this nncleus is outgassing primarily due to CO2, which drags chnnks of ice out of the nnclens. It also shows significant differences in the relative abundance of volatiles from various parts of the nucleus.

  19. [Contact allergy to epoxy resins plastics based on materials collected by the Nofer Institute of Occupational Medicine].

    PubMed

    Kieć-Swierczyńska, Marta; Krecisz, Beata

    2003-01-01

    Of the 5604 patients examined in 1984-2001 for suspected occupational dermatitis, 160 persons (2.8%) showed allergy to epoxy resins plastics. Allergy was more frequent in men (4.9%) than in women (1.2%); in 154 persons, allergy was of occupational etiology (in a group of 160 patients with allergy to epoxy resins, the following proportions were observed: bricklayers, platelayers--17.5%; fitters, turners, machinist millers--13.8%; plastics molders--13.1%; laminators--11.3%; electrical equipment assemblers--10.6%; painters--10.0%). Having compared the frequency of allergy to components of epoxy resins in the years 1984-1993 and 1994-2001, it was found that allergy to resin, reactive diluents and plasticizers was on increase, whereas allergy to amines and acid anhydrides hardeners was on decrease. In a group of 13 chemical compounds entering into the composition of epoxy resins, epoxy resin contributed to the largest number of positive patch tests (77.5% of epoxy-allergic persons). This was followed by triethylenetetramine (23.1%), ethylenediamine (13.1%), phthalic anhydride (8.1%), diethylenetetramine (6.9%) and phenylglycidylether (6.2%). In addition, three patients reacted to both epoxy resin and cycloaliphatic resin.

  20. Identification of non-heme diiron proteins that catalyze triple bond and epoxy group formation.

    PubMed

    Lee, M; Lenman, M; Banaś, A; Bafor, M; Singh, S; Schweizer, M; Nilsson, R; Liljenberg, C; Dahlqvist, A; Gummeson, P O; Sjödahl, S; Green, A; Stymne, S

    1998-05-08

    Acetylenic bonds are present in more than 600 naturally occurring compounds. Plant enzymes that catalyze the formation of the Delta12 acetylenic bond in 9-octadecen-12-ynoic acid and the Delta12 epoxy group in 12,13-epoxy-9-octadecenoic acid were characterized, and two genes, similar in sequence, were cloned. When these complementary DNAs were expressed in Arabidopsis thaliana, the content of acetylenic or epoxidated fatty acids in the seeds increased from 0 to 25 or 15 percent, respectively. Both enzymes have characteristics similar to the membrane proteins containing non-heme iron that have histidine-rich motifs.

  1. Imide modified epoxy matrix resins

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1984-01-01

    The results of a program designed to develop tough imide modified epoxy resins cured by bisimide amine (BIA) hardeners are described. State-of-the-art epoxides MY720 and DER383 were used, and four bismide amines were evaluated. These were the BIA's derived from the 6F anhydride (4,4'-(hexafluoroisopropylidene) bis(phthalic anhydride) and the diamines 3,3'-diaminodiphynyl sulfone, 4,4'-oxygianiline, 4,4'-methylene dianiline, and 1,12-dodecane diamine. A key intermediate, designated 6F anhydride, is required for the synthesis of the bisimide amines. Reaction parameters to synthesize a precursor to the 6F anhydride (6FHC) in high yields were investigated. The catalyst trifluoromethane sulfonic acid was studied. Although small scale runs yielded the 6FHC in 50 percent yield, efforts to ranslate these results to a larger scale synthesis gave the 6FHC in only 9 percent yield. Results show that the concept of using bisimide amine as curing agents to improve the toughness properties of epoxies is valid.

  2. Drinking water contaminants from epoxy resin-coated pipes: A field study.

    PubMed

    Rajasärkkä, Johanna; Pernica, Marek; Kuta, Jan; Lašňák, Jonáš; Šimek, Zdenĕk; Bláha, Luděk

    2016-10-15

    Rehabilitation of aged drinking water pipes is an extensive renovation and increasingly topical in many European cities. Spray-on-lining of drinking water pipes is an alternative cost-effective rehabilitation technology in which the insides of pipes are relined with organic polymer. A commonly used polymer is epoxy resin consisting of monomer bisphenol A (BPA). Leaching of BPA from epoxy lining to drinking water has been a concern among public and authorities. Currently epoxy lining is not recommended in some countries. BPA leaching has been demonstrated in laboratory studies but the behavior and ageing process of epoxy lining in situ is not well known. In this study 6 locations with different age epoxy linings of drinking water pipes done using two distinct technologies were studied. While bisphenol F, 4-n-nonylphenol, and 4-t-octylphenol were rarely found and in trace concentrations, BPA was detected in majority of samples. Pipes lined with the older technology (LSE) leached more BPA than those with more recent technology (DonPro): maxima in cold water were 0.25 μg/L and 10 ng/L, respectively. Incubation of water in pipes 8-10 h prior to sampling increased BPA concentration in cold water 1.1-43-fold. Hot water temperature caused even more BPA leaching - at maximum 23.5 μg/L. The influence of ageing of epoxy lining on BPA leaching on could be shown in case of LSE technology: locations with 8-9 years old lining leached 4-20-fold more BPA compared to a location with 2-year-old lining. Analysis of metals showed that epoxy lining can reduce especially iron concentration in water. No significant burden to water could be shown by the analyzed 72 volatile organic compounds, including epichlorhydrin, precursor used in epoxy resin. Estrogenicity was detected in water samples with the highest BPA loads. Comparable responses of two yeast bioreporters (estrogen receptor α and BPA-targeted) indicated that bisphenol-like compounds were the main cause of estrogenicity

  3. Recognition of epoxy with phage displayed peptides.

    PubMed

    Swaminathan, Swathi; Cui, Yue

    2013-07-01

    The development of a general approach for non-destructive chemical and biological functionalization of epoxy could expand opportunities for both fundamental studies and creating various device platforms. Epoxy shows unique electrical, mechanical, chemical and biological compatibility and has been widely used for fabricating a variety of devices. Phage display has emerged as a powerful method for selecting peptides that possess enhanced selectivity and binding affinity toward a variety of targets. In this letter, we demonstrate for the first time a powerful yet benign approach for identifying binding motifs to epoxy via comprehensively screened phage displayed peptides. Our results show that the epoxy can be selectively recognized with peptide-displaying phages. Further, along with the development of epoxy-based microstructures; recognition of the epoxy with phage displayed peptides can be specifically localized in these microstructures. We anticipate that these results could open up exciting opportunities in the use of peptide-recognized epoxy in fundamental biochemical recognition studies, as well as in applications ranging from analytical devices, hybrid materials, surface and interface, to cell biology.

  4. Mechanical behaviors of hyberbranched epoxy toughened bisphenol F epoxy resin for cryogenic applications

    NASA Astrophysics Data System (ADS)

    Li, Jingwen; Wu, Zhixiong; Huang, Chuanjun; Huang, Rongjin; Li, Laifeng

    2014-01-01

    Epoxy resins have been widely employed in cryogenic engineering fields. In this work, bisphenol F epoxy resin was modified by an aromatic polyester hyperbranched epoxy resin (HTDE-2). Mechanical behaviors of the modified epoxy resins in terms of tensile properties and impact property were studied at both room and cryogenic temperatures. Moreover, the toughening mechanism was discussed by fracture surface morphology analysis. The results demonstrated that, the mechanical properties of composites initially increased until reaches the maximum value with increasing the mass content of the HTDE-2, and then decreased at both room temperature (RT) and 77K. Especially, the impact strength at 77 K was improved 40.7% compared with the pure epoxy matrix when 10 wt% HTDE-2 was introduced. The findings suggest that the HTDE-2 will be an effective toughener for the brittle bisphenol F epoxy resin for cryogenic applications.

  5. Comparative study regarding friction coefficient for three epoxy resins

    NASA Astrophysics Data System (ADS)

    Mihu, G.; Mihalache, I.; Graur, I.; Ungureanu, C.; Bria, V.

    2017-02-01

    Three commercial epoxy diglycidylether of bisphenol-A (DGEBA) were used in this study namely Epiphen RE4020-DE 4020 (Bostik), Epoxy Resin C (R&G Gmbh Waldenbuch), and Epoxy Resin HT-2 (R&G Gmbh Waldenbuch). Epoxy resins are often used for the friction purpose but their friction resistance is quite low and it is thus necessary to enhance their friction resistance. In this paper it is shown how load, sliding velocity, and distance affect friction coefficient of epoxy resins.

  6. Epoxy Foam Encapsulants: Processing and Dielectric Characterization

    SciTech Connect

    Linda Domeier; Marion Hunter

    1999-01-01

    The dielectric performance of epoxy foams was investigated to determine if such materials might provide advantages over more standard polyurethane foams in the encapsulation of electronic assemblies. Comparisons of the dielectric characteristics of epoxy and urethane encapsulant foams found no significant differences between the two resin types and no significant difference between as-molded and machined foams. This study specifically evaluated the formulation and processing of epoxy foams using simple methylhydrosiloxanes as the flowing agent and compared the dielectric performance of those to urethane foams of similar density.

  7. Effect of interfacial chemical bonding and surface topography on adhesion in carbon fiber/epoxy composites

    SciTech Connect

    Drzal, L.T.; Sugiura, N.; Hook, D. |

    1994-12-31

    A series of PAN-based IM6 carbon fibers having varying amounts of surface treatment were, pretreated with compounds representing the constituents encountered in epoxy composites to pre-react any groups on the fiber surface before composite fabrication in order to determine the effect of chemical bonding on fiber-matrix adhesion. Chemical bonding was quantified using XPS. Chemical bonding between reactive groups in amine cured epoxy matrices and the surface groups present on IN46 carbon fibers as a result of commercial surface treatments has been detected although the absolute amount of chemical bonding is low (1-3%). It was found that reaction with monofunctional epoxy groups having hydrocarbon functionalities blocked the surface from further reaction and reduced the adhesion that could be attained to its lowest value. Prereaction with difunctional amines had little effect on adhesion when compared to normal composite fabrication procedures. Prereaction with difunctional epoxy groups did enhance adhesion levels over the level attained in normal composite fabrication methods. These results showed that chemical bonding between epoxy and the carbon fiber surface could increases the adhesion between fiber and matrix about 25% while between the amino group and the carbon fiber surface about 15%. Quantitative measurements of the fiber surface microtopography were made with scanning tunneling microscopy. An increase in roughness was detected with increasing surface treatment. It was concluded that surface roughness also accounted for a significant increase in fiber-matrix adhesion.

  8. Quantitative characterization of solid epoxy resins using comprehensive two dimensional liquid chromatography coupled with electrospray ionization-time of flight mass spectrometry.

    PubMed

    Julka, Samir; Cortes, Hernan; Harfmann, Robert; Bell, Bruce; Schweizer-Theobaldt, Andreas; Pursch, Matthias; Mondello, Luigi; Maynard, Shawn; West, David

    2009-06-01

    A comprehensive multidimensional liquid chromatography system coupled to Electrospray Ionization-Mass Spectrometry (LCxLC-ESI-MS) was developed for detailed characterization and quantitation of solid epoxy resin components. The two orthogonal modes of separation selected were size exclusion chromatography (SEC) in the first dimension and liquid chromatography at critical conditions (LCCC) in the second dimension. Different components present in the solid epoxy resins were separated and quantitated for the first time based on the functional groups and molecular weight heterogeneity. Coupling LCxLC separations with mass spectrometry enabled the identification of components resolved in the two-dimensional space. Several different functional group families of compounds were separated and identified, including epoxy-epoxy and epoxy-alpha-glycol functional oligomers, and their individual molecular weight ranges were determined. Repeatability obtained ranged from 0.5% for the main product to 21% for oligomers at the 0.4% concentration level.

  9. Synthesis of 19-oxygenated 4beta,5beta-epoxy derivatives of 16alpha-hydroxyandrostenedione as mechanistic and catalytic probes for aromatase reaction.

    PubMed

    Numazawa, M; Yoshimura, A

    2000-09-01

    4Beta,5beta-epoxy derivatives of 16alpha-hydroxyandrostenedione (2), one of the natural substrates for aromatase, and its 19-oxygenated compounds 4 and 5 were synthesized as mechanistic and catalytic probes for the enzyme reaction. Treatment of 16alpha-bromoandrostenedione (13) or its 19-hydroxy analog 19 which was prepared from 3beta-hydroxy-19-(tert-butyldimethylsiloxy)androst-5-en-17-one (16) in three steps, with H2O2 and NaOH followed by controlled alkaline hydrolysis with NaOH in aqueous pyridine stereospecifically yielded 4beta,5beta-epoxy-16alpha-ol 15 or 4beta,5beta-epoxy-16alpha,19-diol 22, respectively. Oxidation of 16beta-bromo-4beta,5beta-epoxy-19-ol 21 with pyridinium dichromate followed by controlled alkaline hydrolysis produced 4beta,5beta-epoxy-16alpha-hydroxy-19-al 24.

  10. Tensile properties of epoxy encapsulants

    SciTech Connect

    Guess, T.R.; Wischmann, K.B.; Stavig, M.E.

    1993-02-01

    Tensile properties were measured for nineteen different formulations of epoxy encapsulating materials. Formulations were of different combinations of two neat resins (Epon 828 and Epon 826, with and without CTBN modification), three fillers (ALOX, GNM and mica) and four hardeners (Z, DEA, DETDA-SA and ANH-2). Five of the formulations were tested at -55, -20, 20 and 60C, one formulation at -55, 20 and 71C; and the remaining formulations at 20C. Complete stress-strain curves are presented along with tables of tensile strength, initial modulus and Poisson's ratio. The stress-strain responses are nonlinear and are temperature dependent. The reported data provide information for comparing the mechanical properties of encapsulants containing the suspected carcinogen Shell Z with the properties of encapsulants containing noncarcinogenic hardeners. Also, calculated shear moduli, based on measured tensile moduli and Poisson's ratio, are in very good agreement with reported shear moduli from experimental torsional pendulum tests.

  11. Tensile properties of epoxy encapsulants

    SciTech Connect

    Guess, T.R.; Wischmann, K.B.; Stavig, M.E.

    1993-02-01

    Tensile properties were measured for nineteen different formulations of epoxy encapsulating materials. Formulations were of different combinations of two neat resins (Epon 828 and Epon 826, with and without CTBN modification), three fillers (ALOX, GNM and mica) and four hardeners (Z, DEA, DETDA-SA and ANH-2). Five of the formulations were tested at -55, -20, 20 and 60C, one formulation at -55, 20 and 71C; and the remaining formulations at 20C. Complete stress-strain curves are presented along with tables of tensile strength, initial modulus and Poisson`s ratio. The stress-strain responses are nonlinear and are temperature dependent. The reported data provide information for comparing the mechanical properties of encapsulants containing the suspected carcinogen Shell Z with the properties of encapsulants containing noncarcinogenic hardeners. Also, calculated shear moduli, based on measured tensile moduli and Poisson`s ratio, are in very good agreement with reported shear moduli from experimental torsional pendulum tests.

  12. Structural/Radiation-Shielding Epoxies

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Smith, Joseph G.; Hinkley, Jeffrey; Blattnig, Steve; Delozier, Donavon M.; Watson, Kent A.; Ghose, Sayata

    2009-01-01

    A development effort was directed toward formulating epoxy resins that are useful both as structural materials and as shielding against heavy-ion radiation. Hydrogen is recognized as the best element for absorbing heavy-ion radiation, and high-hydrogen-content polymers are now in use as shielding materials. However, high-hydrogen-content polymers (e.g. polyethylene) are typically not good structural materials. In contrast, aromatic polymers, which contain smaller amounts of hydrogen, often have the strength necessary for structural materials. Accordingly, the present development effort is based on the concept that an ideal structural/ heavy-ion-radiation-shielding material would be a polymer that contains sufficient hydrogen (e.g., in the form of aliphatic molecular groups) for radiation shielding and has sufficient aromatic content for structural integrity.

  13. Breakdown properties of epoxy nanodielectric

    SciTech Connect

    Tuncer, Enis; Cantoni, Claudia; More, Karren Leslie; James, David Randy; Polyzos, Georgios; Sauers, Isidor; Ellis, Alvin R

    2010-01-01

    Recent developments in polymeric dielectric nanocomposites have shown that these novel materials can improve design of high voltage (hv) components and systems. Some of the improvements can be listed as reduction in size (compact hv systems), better reliability, high energy density, voltage endurance, and multifunctionality. Nanodielectric systems demonstrated specific improvements that have been published in the literature by different groups working with electrical insulation materials. In this paper we focus on the influence of in-situ synthesized titanium dioxide (TiO{sub 2}) nanoparticles on the dielectric breakdown characteristics of an epoxy-based nanocomposite system. The in-situ synthesis of the particles creates small nanoparticles on the order of 10 nm with narrow size distribution and uniform particle dispersion in the matrix. The breakdown strength of the nanocomposite was studied as a function of TiO{sub 2} concentration at cryogenic temperatures. It was observed that between 2 and 6wt% yields high breakdown values for the nanodielectric.

  14. Physical aging in graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Kong, E. S. W.

    1983-01-01

    Sub-Tg annealing has been found to affect the properties of graphite/epoxy composites. The network epoxy studied was based on the chemistry of tetraglycidyl 4,4'-diamino-diphenyl methane (TGDDM) crosslinked by 4,4'-diamino-diphenyl sulfone (DDS). Differential scanning calorimetry, thermal mechanical analysis, and solid-state cross-polarized magic-angle-spinning nuclear magnetic resonance spectroscopy have been utilized in order to characterize this process of recovery towards thermodynamic equilibrium. The volume and enthalpy recovery as well as the 'thermoreversibility' aspects of the physical aging are discussed. This nonequilibrium and time-dependent behavior of network epoxies are considered in view of the increasingly wide applications of TGDDM-DDS epoxies as matrix materials of structural composites in the aerospace industry.

  15. Postbuckling behavior of graphite-epoxy panels

    NASA Technical Reports Server (NTRS)

    Starnes, J. H., Jr.; Dickson, J. N.; Rouse, M.

    1984-01-01

    Structurally efficient fuselage panels are often designed to allow buckling to occur at applied loads below ultimate. Interest in applying graphite-epoxy materials to fuselage primary structure led to several studies of the post-buckling behavior of graphite-epoxy structural components. Studies of the postbuckling behavior of flat and curved, unstiffened and stiffened graphite-epoxy panels loaded in compression and shear were summarized. The response and failure characteristics of specimens studied experimentally were described, and analytical and experimental results were compared. The specimens tested in the studies described were fabricated from commercially available 0.005-inch-thick unidirectional graphite-fiber tapes preimpregnated with 350 F cure thermosetting epoxy resins.

  16. Structure Property Relationships of Biobased Epoxy Resins

    NASA Astrophysics Data System (ADS)

    Maiorana, Anthony Surraht

    The thesis is about the synthesis, characterization, development, and application of epoxy resins derived from sustainable feedstocks such as lingo-cellulose, plant oils, and other non-food feedstocks. The thesis can be divided into two main topics 1) the synthesis and structure property relationship investigation of new biobased epoxy resin families and 2) mixing epoxy resins with reactive diluents, nanoparticles, toughening agents, and understanding co-curing reactions, filler/matrix interactions, and cured epoxy resin thermomechanical, viscoelastic, and dielectric properties. The thesis seeks to bridge the gap between new epoxy resin development, application for composites and advanced materials, processing and manufacturing, and end of life of thermoset polymers. The structures of uncured epoxy resins are characterized through traditional small molecule techniques such as nuclear magnetic resonance, high resolution mass spectrometry, and infrared spectroscopy. The structure of epoxy resin monomers are further understood through the process of curing the resins and cured resins' properties through rheology, chemorheology, dynamic mechanical analysis, tensile testing, fracture toughness, differential scanning calorimetry, scanning electron microscopy, thermogravimetric analysis, and notched izod impact testing. It was found that diphenolate esters are viable alternatives to bisphenol A and that the structure of the ester side chain can have signifi-cant effects on monomer viscosity. The structure of the cured diphenolate based epoxy resins also influence glass transition temperature and dielectric properties. Incorporation of reactive diluents and flexible resins can lower viscosity, extend gel time, and enable processing of high filler content composites and increase fracture toughness. Incorpora-tion of high elastic modulus nanoparticles such as graphene can provide increases in physical properties such as elastic modulus and fracture toughness. The synthesis

  17. Impregnating magnetic components with MDA free epoxy

    SciTech Connect

    Sanchez, R.O.; Domeier, L.; Gunewardena, S.

    1995-08-01

    This paper describes the use of {open_quotes}Formula 456{close_quotes} an aliphatic amine cured epoxy for impregnating coils. Methylene dianiline (MDA) has been used for more than 20 years as the curing agent for various epoxy formulations throughout the Department of Energy. Sandia National Laboratories began the process of replacing MDA with other formulations because of regulations imposed by OSHA on the use of MDA.

  18. Electrical properties of epoxies and film resistors

    NASA Technical Reports Server (NTRS)

    Sergent, J. E.

    1976-01-01

    The reliability of hybrid microcircuits has been enhanced in recent years by the use of organic adhesives as a replacement for solder and eutectics. The epoxies have been the most effective and widely used material for this application. Methods for measuring the electrical and mechanical properties of epoxies are developed. Data are given for selected conductive adhesives at high and low frequencies. The temperature coefficients of resistance of thick film resistors are presented.

  19. Cavitation in block copolymer modified epoxy

    NASA Astrophysics Data System (ADS)

    Declet-Perez, Carmelo; Francis, Lorraine; Bates, Frank

    2013-03-01

    Today, brittleness in epoxy networks limits most commercial applications. Significant toughness can be imparted by adding small amounts of micelle forming block copolymers (BCP) without compromising critical properties such as high use temperature and modulus. Curing the network locks in the self-assembled BCP micellar structures formed in the monomer resin providing control of the resulting morphology. Despite significant research over the last decade, a complete description of the parameters influencing toughness in block copolymer modified epoxies is still lacking. In this presentation we compare the ultimate mechanical behavior of epoxies modified with spherical micelle forming BCP's containing rubbery and glassy cores using real-time in-situ small-angle X-ray scattering (SAXS) performed during tensile deformation. Striking differences in the 2D SAXS patterns were documented for epoxies modified with rubbery (PEP) versus glassy (PS) micelle cores. Rubbery cores dilate by 100% in volume upon specimen yielding, while the glassy micelle cores deform at approximately constant volume. These results provide direct evidence of a cavitation mediated mechanism for toughness in block copolymer modified epoxies. We further interpret characteristic butterfly features in the 2D SAXS patterns in terms of epoxy network deformation. Support was provided by the NSF sponsored MRSEC at the University of Minnesota

  20. Improved gas chromatography-flame ionization detector analytical method for the analysis of epoxy fatty acids.

    PubMed

    Mubiru, Edward; Shrestha, Kshitij; Papastergiadis, Antonios; De Meulenaer, Bruno

    2013-11-29

    In this study an improved method for analysis of epoxy fatty acids is reported. Data obtained from analysis of polar fatty acids has previously been presented, but due to the high number of compounds that co-elute in the polar fraction, the resultant chromatograms are complex which may lead to compromising the accuracy of the data. A three steps separation of fatty acid methyl esters (FAMEs) by solid-phase extraction (SPE) on a silica gel column to remove hydroxy fatty acid interferences was proposed. This approach is opposed to a two step separation procedure that has been often used to prevent analytical interferences caused by non-altered fatty acids. A gas chromatograph with a flame ionization detector (GC-FID) equipped with a polar CP-Sil 88™ column was used. Quantification was based on the use of methyl nonadecanoate (C19:0), as an internal standard. Individual mono epoxy fatty acids were well separated without co-eluting compounds. The optimized method was finally applied to screen epoxy fatty acids in 37 fresh oil samples. Results obtained for the total epoxy fatty acids were in the range 0.03-2mgg(-1) of oil with repeatability coefficient of variation (CV) ranging from 2.8 to 9.9% for duplicate analysis showing that the results obtained are repeatable.

  1. New epoxy/episulfide resin system for electronic and coating applications: Curing mechanisms and properties

    NASA Astrophysics Data System (ADS)

    Tsuchida, Katsuyuki

    This work involves research on a new resin system useful for printed circuit board and protective coating applications. The system provides excellent adhesion to copper and corrosion resistance for copper. The research involved detailed studies of the reaction mechanisms, and correlation of these mechanisms with the observed properties. The epoxy/episulfide system, when used with a dicyandiamide (DICY) curing agent, exhibits better adhesion to copper substrate, a better pot life and prepreg storage life, a lower thermal expansion coefficient, a lower heat of reaction, a lower degradation temperature, and higher water absorption as compared with the standard epoxy system. From model compound studies, the sulfur of the opened episulfide ring reacts with copper, resulting in a durable bond between the copper and matrix resin even after water boiling. Since the S- formed by the reaction of the episulfide with the curing agent easily reacts with both the episulfide and the epoxy, a C-S-C bond is formed and more unreacted curing agent remains as compared to the standard epoxy system. The new bond formation causes a lower thermal expansion coefficient and somewhat lower degradation temperature. The unreacted curing agent causes slightly higher water absorption. Since the episulfide ring has less stress than the epoxy ring the epoxy/episulfide system shows lower heat of reaction, i.e., a lower exotherm. and lower shrinkage. The epoxy/episuffide system, when used with a polyamide curing agent, exhibits better corrosion protection for copper substrates, a lower thermal expansion coefficient and a lower degradation temperature. From model compound studies, the curing reactions are changed by changing curing temperature and the presence of copper: the episulfide homopolymerization and the S--epoxy reactions increase in the case of room temperature curing or in the presence of copper. In the presence of copper, the sulfur of the episulfide also reacts with copper, although the

  2. Effects of Aging Treatment on Mechanical Properties of Sn-58Bi Epoxy Solder on ENEPIG-Surface-Finished PCB

    NASA Astrophysics Data System (ADS)

    Kim, Jungsoo; Myung, Woo-Ram; Jung, Seung-Boo

    2016-11-01

    The mechanical properties of Sn-58Bi epoxy solder were evaluated by low-speed shear testing as functions of aging time and temperature. To determine the effects of epoxy, the interfacial reaction and mechanical properties of both Sn-58Bi and Sn-58Bi epoxy solder were investigated after aging treatment. The chemical composition and growth kinetics of the intermetallic compound (IMC) formed at the interface between Sn-58Bi solder and electroless nickel electroless palladium immersion gold (ENEPIG) surface finish were analyzed. Sn-58Bi solder paste was applied by stencil-printing on flame retardant-4 substrate, then reflowed. Reflowed samples were aged at 85°C, 95°C, 105°C, and 115°C for up to 1000 h. (Ni,Pd)3Sn4 IMC formed between Sn-58Bi solder and ENEPIG surface finish after reflow. Ni3Sn4 and Ni3P IMCs formed at the interface between (Ni,Pd)3Sn4 IMC and ENEPIG surface finish after aging at 115°C for 300 h. The overall IMC growth rate of Sn-58Bi solder joint was higher than that of Sn-58Bi epoxy solder joint during aging. The shear strength of Sn-58Bi epoxy solder was about 2.4 times higher than that of Sn-58Bi solder due to the blocking effect of epoxy, and the shear strength decreased with increasing aging time.

  3. Physical aging and its influence on the reliability of network epoxies and epoxy-matrix composites

    NASA Technical Reports Server (NTRS)

    Heinemann, K.

    1983-01-01

    The matrix-dominated physical and mechanical properties of a carbon fiber reinforced epoxy composite and a neat epoxy resin were found to be affected by sub-Tg annealing in nitrogen and dark atmosphere. Postcured specimens of Thornel 300 carbon-fiber/Fiberite 934 epoxy as well as Fiberite 934 epoxy resin were quenched from above Tg and given annealing at 140 C, 110 C, or 80 C, for time up to one-hundred thousand minutes. No weight loss was observed during annealing at these temperatures. Significant variations were found in density, modulus, hardness, damping, moisture absorption ability, thermal expansivity. Moisture-epoxy interactious were also studied. The kinetics of aging as well as the molecular aggregation during this densification process were monitored by differential scanning calorimetry, dynamic mechanical analysis, density gradient column, microhardness tester, Instron, and solid-state nuclear magnetic resonance spectroscopy.

  4. Wet air oxidation of epoxy acrylate monomer industrial wastewater.

    PubMed

    Yang, Shaoxia; Liu, Zhengqian; Huang, Xiaohui; Zhang, Beiping

    2010-06-15

    Epoxy acrylate monomer industrial wastewater contained highly concentrated and toxic organic compounds. The wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were used to eliminate pollutants in order to examine the feasibility of the WAO/CWAO as a pre-treatment method for the industrial wastewater. The results showed that in the WAO 63% chemical oxygen demand (COD) and 41% total organic carbon (TOC) removals were achieved and biological oxygen demand (BOD(5))/COD ratio increased from 0.13 to 0.72 after 3h reaction at 250 degrees C, 3.5MPa and the initial concentration of 100g(COD)/L. Among homogenous catalysts (Cu(2+), Fe(2+), Fe(3+) and Mn(2+) salts), Cu(2+) salt exhibited better performance. CuO catalyst was used in the CWAO of the wastewater, COD and TOC conversion were 77 and 54%, and good biodegradability was achieved. The results proved that the CWAO was an effective pre-treatment method for the epoxy acrylate monomer industrial wastewater.

  5. Fluorinated Alkyl Ether Epoxy Resin Compositions and Applications Thereof

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J. (Inventor); Connell, John W. (Inventor); Smith, Joseph G. (Inventor); Siochi, Emilie J. (Inventor); Gardner, John M. (Inventor); Palmieri, Frank M. (Inventor)

    2017-01-01

    Epoxy resin compositions prepared using amino terminated fluoro alkyl ethers. The epoxy resin compositions exhibit low surface adhesion properties making them useful as coatings, paints, moldings, adhesives, and fiber reinforced composites.

  6. Electrical properties of epoxies used in hybrid microelectronics

    NASA Technical Reports Server (NTRS)

    Stout, C. W.

    1976-01-01

    The electrical properties and basic characteristics of the structure of conductive epoxies were studied. The results of the experimental work performed to measure the electrical properties of epoxies are presented.

  7. Influence of Expanding Monomer on Carbon Fiber Reinforced Epoxy Composites

    DTIC Science & Technology

    1990-06-01

    copolymerize. Embedded single filament tensile test results were compared for samples containing DGEBA -epoxy cured with m-phenylene (mPDA) wi_% those for...stage before the DNSOC begins to copolymerize. Embedded single filament tensile test results were compared for samples containing DGEBA -epoxy cured...Dr. Piggott incorporated DNSOC into DGEBA (the diglycidyl ether of bisphenol A) type epoxies and found that epoxy susceptibility to water was reduced

  8. Chromium Ions Improve Moisure Resistance of Epoxy Resins

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.; Stoakley, D. M.; Singh, J. J.; Sprinkle, D. R.

    1986-01-01

    Broad spectrum of thermosetting epoxy resins used on commercial and military aircraft, primarily as composite matrices and adhesives. In new technique, chromium-ion containing epoxy with improved resistance to moisture produced where chromium ions believed to prevent absorption of water molecules by coordinating themselves to hydroxyl groups on epoxy chain. Anticipated that improved epoxy formulation useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft. Improvement made without sacrifice in mechanical properties of polymer.

  9. Evaluation of epoxy systems for use in SBASI

    NASA Technical Reports Server (NTRS)

    Coultas, T. J.

    1971-01-01

    The purpose of the test program was to evaluate the performance of different epoxy systems as replacements for existing epoxy systems in the SBASI. The three areas of investigation were the connector shell potting, the epoxy tape under the charge cup, and the epoxy impregnated fiberglass over the output charge. Factors considered, in addition to performance, were availability, shelf life, pot life, and effect on producibility and cost.

  10. Thermal properties of epoxy composites filled with boric acid

    NASA Astrophysics Data System (ADS)

    Visakh, P. M.; Nazarenko, O. B.; Amelkovich, Yu A.; Melnikova, T. V.

    2015-04-01

    The thermal properties of epoxy composites filled with boric acid fine powder at different percentage were studied. Epoxy composites were prepared using epoxy resin ED-20, boric acid as flame-retardant filler, hexamethylenediamine as a curing agent. The prepared samples and starting materials were examined using methods of thermal analysis, scanning electron microscopy and infrared spectroscopy. It was found that the incorporation of boric acid fine powder enhances the thermal stability of epoxy composites.

  11. The toughening mechanisms in epoxy-silica nanocomposites and hybrid epoxy-silica-rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Liang, Yi-Ling

    In order to improve the crack resistance of epoxy resins, either soft, micron size rubber particles or rigid, micron size spheres are commonly added as toughening agents. The toughening mechanisms induced by soft rubber particles and rigid spheres are different. The fracture behavior of toughened epoxy resins usually show a peak or plateau when the fraction of toughening agent reaches certain level. Therefore, epoxy resins modified by the incorporation of two types of toughening agents can be developed known as the hybrid composites with toughness greater than that when only one type toughening agent is used. Recently, a well dispersed, nanometer size silica spheres produced by sol-gel technology have been added into epoxy resin. The toughening behavior of the epoxy-silica nanocomposite (ESNs) is very interesting since it contradicts many conventional predictions. Moreover, a significant improvement of fracture behavior has been reported in hybrid epoxy-silica-rubber nanocomposite (HESRNs) when a small amount of nanosilica is used. However the toughening mechanisms in ESNs and HESRNs are not clear. The focus of this study is to understand the effect of nanosilica size as well as the nanosilica dispersion on the toughening behavior in ESNs and HESRNs. In addition, a system of hybrid epoxy-rubber?rubber blends (HERRBs) is developed to further elucidate the role of nanosilica in toughening mechanisms of ESNs, HESRNs.

  12. Food contamination from epoxy resins and organosols used as can coatings: analysis by gradient NPLC.

    PubMed

    Biedermann, M; Grob, K

    1998-07-01

    Normal phase LC with gradient elution enabled the analysis of a broadened range of oligomers of BADGE (Bisphenol-A diglycidyl ether) and Novolak compounds in canned foods, such as sea foods in oil, meat products and soups. A major component released from Bisphenol-A resins was identified as the cyclo-(Bisphenol-A monoglycidyl ether) dimer and was commonly present in foods at concentrations of around 1 mg/kg. For the epoxy Novolaks, concentrations of the three- to six-ring compounds often far exceeded those of BFDGE (Bisphenol-F diglycidyl ether) and reached 20 mg/kg in foods. A two-step acylation is proposed for the detection of epoxy components.

  13. Hygrothermal expansion of Kevlar 49/epoxy and S2-glass/epoxy composites

    SciTech Connect

    Lo, S.Y.; Hahn, H.T.

    1982-11-01

    Ply failure occurred during preconditioning at 75/sup 0/C of (0/90)/sub 2S/ S2-glass/epoxy and Kevlar 49/epoxy laminates. Wet specimens showed different thermal expansion beavior near and above the glass transition temperature. Various available theories can be used to predict the thermal expansion coefficients. Stress analysis showed that the compressive normal stress at the interface in Kevlar 49/epoxy after cure is very small compared with those in other composites. Significant and rapid changes in the transverse coefficient of thermal expansion occurs in the T/sub g/ region. The two-phase diffusion model is a good representation of the diffusion behavior. Desorption process reveals a higher diffusion coefficient than absorption. S2-glass/epoxy was found to be unstable under the conditions applied, with cracking and losses during desorption. Maximum moisture contents were approx. 0.31% at 75/sup 0/C/75% RH and approx. 0.412% at 75/sup 0/C/water. The composite swelled transversely up to about 0.11 and 0.16%. Kevlar 49/epoxy was more stable than S2-glass/epoxy; max moisture contents were approx. 2.47% at 75/sup 0/C/75% RH and approx. 5.5% at 75/sup 0/C/water. The composite swelled transversely up to 1.0 and 2.23%. Results indicate that Kevlar 49 fibers swell radially. Relation between swelling strain and moisture content undergoes hysteresis during moisture cycling. Relation between swelling strain and moisture concentration is fairly linear for S2-glass/epoxy, Kevlar 49/epoxy and AS 3501/5 graphite/epoxy and only weakly depends on the material system. The equilibrium moisture content in (+-45)/sub 2S/ laminate is higher than in unidirectional lamina. The equilibrium thickness swelling strain can be predicted by laminated plate theory.

  14. Free-volume characteristics of epoxies

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Eftekhari, Abe; Shultz, William J.; St.clair, Terry L.

    1992-01-01

    Positron annihilation spectroscopy was used to measure free-volume characteristics of selected epoxies. Fluorene resins, a new family of high-temperature thermosetting resins, were selected as the test medium. Experimental results indicate that the free-volume cell size V sub f varies with the molecular weight between the cross-links M sub c according to an equation of the form V sub f = AM sub c sup B, where A and B are structural constants. In two of the samples, the concentration of bulky fluorene groups was increased in the network backbone by replacement of some of the conventional bisphenol A epoxy resin with fluorene-derived epoxy resin. This resulted in an increase in their glass transition temperature for a given level of cross-linking. It was found that in these samples, the Doppler broadening of the annihilation peak decreases with the increasing fluorene content, presumably due to enhanced damping of the chain motions.

  15. RADIATION EFFECTS ON EPOXY CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-05-30

    Carbon fiber-reinforced bisphenol-A epoxy matrix composite was evaluated for gamma radiation resistance. The composite was exposed to total gamma doses of 50, 100, and 200 Mrad. Irradiated and baseline samples were tested for tensile strength, hardness and evaluated using FTIR (Fourier transform infrared) spectroscopy and DSC (differential scanning calorimetry) for structural changes. Scanning electron microscopy was used to evaluate microstructural behavior. Mechanical testing of the composite bars revealed no apparent change in modulus, strain to failure, or fracture strength after exposures. However, testing of only the epoxy matrix revealed changes in hardness, thermal properties, and FTIR results with increasing gamma irradiation. The results suggest the epoxy within the composite can be affected by exposure to gamma irradiation.

  16. Epoxy coated reinforcement in bridge decks

    NASA Astrophysics Data System (ADS)

    Wills, J.

    A review was conducted of methods relating to the use of epoxy coated reinforcing bars for bridge decks and their potential for use in the United Kingdom. A survey of work carried out in the USA was carried out and the analysis used in a preliminary cost study. The options of having either a hot rolled asphalt surfacing or a permanently exposed concrete wearing surface were considered. It was concluded that epoxy coating of the top steel in addition to current waterproofing practice would provide, at relatively little extra cost, additional assurance that the reinforcement would be adequately protected throughout the life of a bridge. Current design rules do not permit decks with permanently exposed concrete wearing surface without waterproofing. Epoxy coating may afford a means of introducing such decks but before a positive recommendation to delete waterproofing can be made further studies would have to be undertaken.

  17. Physical aging in graphite epoxy composites

    NASA Technical Reports Server (NTRS)

    Kong, E. S. W.

    1981-01-01

    The matrix dominated mechanical behavior of a graphite epoxy composite was found to be affected by sub Tg annealing. Postcured + or - 45 deg 4S specimens of Thornel 300 graphite/Narmco 5208 epoxy were quenched from above Tg and given a sub Tg annealing at 140 C for times up to 10 to the 5th power min. The ultimate tensile strength, strain to break, and toughness of the composite material were found to decrease as functions of sub Tg annealing time. No weight loss was observed during the sub Tg annealing. The time dependent change in mechanical behavior is explained on the basis of free volume changes that are related to the physical aging of the nonequilibrium glassy network epoxy. The results imply possible changes in composite properties with service time.

  18. Unanticipated Effects of Epoxy Impregnating Transformers

    SciTech Connect

    SANCHEZ,ROBERT O.; ARCHER,WENDEL E.

    2000-08-23

    Many Sandia components for military applications are designed for a 20-year life. In order to determine if magnetic components meet that requirement, the parts are subjected to selected destructive tests. This paper reviews the re-design of a power transformer and the tests required to prove-in the re-design. The re-design included replacing the Epon 828/Mica/methylenedianiline (curing agent Z) epoxy encapsulant with a recent Sandia National Laboratory (SNL) developed epoxy encapsulant. The new encapsulant reduces the Environmental Safety and Health (ES and H) hazards. Life testing of this re-designed transformer generated failures; an open secondary winding. An experimental program to determine the cause of the broken wires and an improved design to eliminate the problem was executed. This design weakness was corrected by reverting to the hazardous epoxy system.

  19. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  20. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  1. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  2. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  3. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  4. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section...

  5. 40 CFR 721.10113 - Thioether epoxy (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Thioether epoxy (generic). 721.10113... Substances § 721.10113 Thioether epoxy (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as thioether epoxy (PMN P-04-547) is subject...

  6. 40 CFR 721.2755 - Cycloaliphatic epoxy resin (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cycloaliphatic epoxy resin (generic... Substances § 721.2755 Cycloaliphatic epoxy resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as cycloaliphatic epoxy resin...

  7. 40 CFR 721.10113 - Thioether epoxy (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Thioether epoxy (generic). 721.10113... Substances § 721.10113 Thioether epoxy (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as thioether epoxy (PMN P-04-547) is subject...

  8. 40 CFR 721.2755 - Cycloaliphatic epoxy resin (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Cycloaliphatic epoxy resin (generic... Substances § 721.2755 Cycloaliphatic epoxy resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as cycloaliphatic epoxy resin...

  9. 40 CFR 721.2752 - Epoxy resin containing phosphorus (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Epoxy resin containing phosphorus... Specific Chemical Substances § 721.2752 Epoxy resin containing phosphorus (generic). (a) Chemical substance... epoxy resin containing phosphorus (PMN P-00-912) is subject to reporting under this section for...

  10. 40 CFR 721.2752 - Epoxy resin containing phosphorus (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Epoxy resin containing phosphorus... Specific Chemical Substances § 721.2752 Epoxy resin containing phosphorus (generic). (a) Chemical substance... epoxy resin containing phosphorus (PMN P-00-912) is subject to reporting under this section for...

  11. 40 CFR 721.2752 - Epoxy resin containing phosphorus (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Epoxy resin containing phosphorus... Specific Chemical Substances § 721.2752 Epoxy resin containing phosphorus (generic). (a) Chemical substance... epoxy resin containing phosphorus (PMN P-00-912) is subject to reporting under this section for...

  12. 40 CFR 721.2755 - Cycloaliphatic epoxy resin (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Cycloaliphatic epoxy resin (generic... Substances § 721.2755 Cycloaliphatic epoxy resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as cycloaliphatic epoxy resin...

  13. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section...

  14. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section...

  15. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section...

  16. 40 CFR 721.10113 - Thioether epoxy (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Thioether epoxy (generic). 721.10113... Substances § 721.10113 Thioether epoxy (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as thioether epoxy (PMN P-04-547) is subject...

  17. 40 CFR 721.2752 - Epoxy resin containing phosphorus (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Epoxy resin containing phosphorus... Specific Chemical Substances § 721.2752 Epoxy resin containing phosphorus (generic). (a) Chemical substance... epoxy resin containing phosphorus (PMN P-00-912) is subject to reporting under this section for...

  18. 40 CFR 721.10113 - Thioether epoxy (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Thioether epoxy (generic). 721.10113... Substances § 721.10113 Thioether epoxy (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as thioether epoxy (PMN P-04-547) is subject...

  19. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section...

  20. 40 CFR 721.10113 - Thioether epoxy (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Thioether epoxy (generic). 721.10113... Substances § 721.10113 Thioether epoxy (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as thioether epoxy (PMN P-04-547) is subject...

  1. 40 CFR 721.2755 - Cycloaliphatic epoxy resin (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cycloaliphatic epoxy resin (generic... Substances § 721.2755 Cycloaliphatic epoxy resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as cycloaliphatic epoxy resin...

  2. 40 CFR 721.2755 - Cycloaliphatic epoxy resin (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Cycloaliphatic epoxy resin (generic... Substances § 721.2755 Cycloaliphatic epoxy resin (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as cycloaliphatic epoxy resin...

  3. 40 CFR 721.2752 - Epoxy resin containing phosphorus (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Epoxy resin containing phosphorus... Specific Chemical Substances § 721.2752 Epoxy resin containing phosphorus (generic). (a) Chemical substance... epoxy resin containing phosphorus (PMN P-00-912) is subject to reporting under this section for...

  4. Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

    NASA Astrophysics Data System (ADS)

    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.

  5. Epoxy-coated containers easily opened by wire band

    NASA Technical Reports Server (NTRS)

    Mc Coy, J. W.

    1966-01-01

    Epoxy coating reduces punctures, abrasions, and contamination of synthetic cellular containers used for shipping and storing fragile goods and equipment. A wire band is wound around the closure joint, followed by the epoxy coating. The container can then be easily opened by pulling the wire through the epoxy around the joint.

  6. 40 CFR 721.320 - Acrylamide-substituted epoxy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Acrylamide-substituted epoxy. 721.320... Substances § 721.320 Acrylamide-substituted epoxy. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acrylamide-substituted epoxy (PMN...

  7. 40 CFR 721.320 - Acrylamide-substituted epoxy.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Acrylamide-substituted epoxy. 721.320... Substances § 721.320 Acrylamide-substituted epoxy. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acrylamide-substituted epoxy (PMN...

  8. 40 CFR 721.320 - Acrylamide-substituted epoxy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Acrylamide-substituted epoxy. 721.320... Substances § 721.320 Acrylamide-substituted epoxy. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acrylamide-substituted epoxy (PMN...

  9. 40 CFR 721.320 - Acrylamide-substituted epoxy.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Acrylamide-substituted epoxy. 721.320... Substances § 721.320 Acrylamide-substituted epoxy. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acrylamide-substituted epoxy (PMN...

  10. 40 CFR 721.320 - Acrylamide-substituted epoxy.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Acrylamide-substituted epoxy. 721.320... Substances § 721.320 Acrylamide-substituted epoxy. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acrylamide-substituted epoxy (PMN...

  11. Control of pore size in epoxy systems.

    SciTech Connect

    Sawyer, Patricia Sue; Lenhart, Joseph Ludlow; Lee, Elizabeth; Kallam, Alekhya; Majumdar, Partha; Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J.; Celina, Mathias Christopher; Bahr, James; 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.

  12. Kevlar 49/Epoxy COPV Aging Evaluation

    NASA Technical Reports Server (NTRS)

    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.

  13. Recent developments in the production of spin-cast epoxy mirrors

    NASA Astrophysics Data System (ADS)

    Brodhacker, K. Lisa; Ritter, Joe; La Croix, Andrew; Holenstein, Bruce; Genet, Russell M.

    2014-03-01

    NASA is currently developing optical communications to use with its spacecraft—both in earth-orbit and in deep space. This may allow spacecraft to use small, pencil-beam telescopes instead of large, wide-beam microwave antennas, potentially saving weight, reducing transmission power, and increasing communications bandwidth. The Earth side of such communications links will require a network of low cost, ground-based telescopes. The ground support mission mentioned above would benefit from the development of lightweight, low cost, 1 to 2 meter aperture telescopes. The key is the development of low cost, diffraction limited mirrors that cost orders of magnitude less than NASA's current telescope mirrors, have a drastically reduced manufacturing time, with significant weight reduction (low areal density). Spin-cast epoxy mirrors do not require any grinding, polishing, or figuring and therefore have the potential for low cost, short production time, and light weight. The specially-formulated thin epoxy described here naturally forms a parabolic surface when spun at constant velocity and once it hardens, the mirror surface is ready for use except for a reflective coating. A recently produced 50cm diameter f/2 spin-cast epoxy mirror has been measured to have a 6-8 micron RMS surface figure deviation and approximately 1 nm microroughness. Other advances include the synthesis and co-polymerization of spiro orthocarbonate compounds (SOCs) to reduce chemical shrinkage and the engineering of a stiff mold to hold the curing epoxy as it spins.

  14. Cure Kinetics of Epoxy Nanocomposites Affected by MWCNTs Functionalization: A Review

    PubMed Central

    Saeb, Mohammad Reza; Bakhshandeh, Ehsan; Khonakdar, Hossein Ali; Mäder, Edith; Scheffler, Christina; Heinrich, Gert

    2013-01-01

    The current paper provides an overview to emphasize the role of functionalization of multiwalled carbon nanotubes (MWCNTs) in manipulating cure kinetics of epoxy nanocomposites, which itself determines ultimate properties of the resulting compound. In this regard, the most commonly used functionalization schemes, that is, carboxylation and amidation, are thoroughly surveyed to highlight the role of functionalized nanotubes in controlling the rate of autocatalytic and vitrification kinetics. The current literature elucidates that the mechanism of curing in epoxy/MWCNTs nanocomposites remains almost unaffected by the functionalization of carbon nanotubes. On the other hand, early stage facilitation of autocatalytic reactions in the presence of MWCNTs bearing amine groups has been addressed by several researchers. When carboxylated nanotubes were used to modify MWCNTs, the rate of such reactions diminished as a consequence of heterogeneous dispersion within the epoxy matrix. At later stages of curing, however, the prolonged vitrification was seen to be dominant. Thus, the type of functional groups covalently located on the surface of MWCNTs directly affects the degree of polymer-nanotube interaction followed by enhancement of curing reaction. Our survey demonstrated that most widespread efforts ever made to represent multifarious surface-treated MWCNTs have not been directed towards preparation of epoxy nanocomposites, but they could result in property synergism. PMID:24348181

  15. Preparation of well-controlled three-dimensional skeletal hybrid monoliths via thiol-epoxy click polymerization for highly efficient separation of small molecules in capillary liquid chromatography.

    PubMed

    Lin, Hui; Chen, Lianfang; Ou, Junjie; Liu, Zhongshan; Wang, Hongwei; Dong, Jing; Zou, Hanfa

    2015-10-16

    Two kinds of hybrid monoliths were first prepared via thiol-epoxy click polymerization using a multi-epoxy monomer, octaglycidyldimethylsilyl POSS (POSS-epoxy), and two multi-thiols, trimethylolpropanetris(3-mercaptopropionate) (TPTM) and pentaerythritoltetrakis(3-mercaptopropionate) (PTM), respectively, as the precursors. The resulting two hybrid monoliths (assigned as POSS-epoxy-TPTM and POSS-epoxy-PTM) not only possessed high thermal, mechanical and chemical stabilities, but also exhibited well-controlled 3D skeletal microstructure and high efficiency in capillary liquid chromatography (cLC) separation of small molecules. The highest column efficiency reached 182,700N/m (for butylbenzene) on the monolith POSS-epoxy-PTM at the velocity of 0.75mm/s. Furthermore, the hybrid monolith POSS-epoxy-PTM was successfully applied for cLC separations of various samples, not only standard compounds such as alkylbenzenes, PAHs, phenols and dipeptides, as well as intact proteins, but also complex samples of EPA 610 and BSA digest.

  16. Pretreatment of Kapton-coated cable for epoxy adhesion

    NASA Astrophysics Data System (ADS)

    Carley, J. F.

    1984-01-01

    A new system to protect bonded strain gages that will be attached to the MFTF magnets was tested and indicated falling electrical resistance to ground, which is attributed to the infiltration of moisture. The most likely infiltration route seemed to be along the Kapton lead cable, which has an outer space of FEP fluorocarbon resin. The treated ends are embedded in the epoxy sealant, Hysol EA 934, a compound containing 70 wt % of asbestos. The tensile shear stresses required to pull the wires out of these embedments were measured. It is shown that the three levels of treatment are equally effective in raising the bond strength from 377 psi for the untreated cable to about twice that, 763 psi. It appears that the 40-s exposure to Tetra-Etch has penetrated the 0.5 mil fluorocarbon coating and attacks the Kapton film and the conductor coatings inside it.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Effect of Liquid-Crystalline Epoxy Backbone Structure on Thermal Conductivity of Epoxy-Alumina Composites

    NASA Astrophysics Data System (ADS)

    Giang, Thanhkieu; Kim, Jinhwan

    2017-01-01

    In a series of papers published recently, we clearly demonstrated that the most important factor governing the thermal conductivity of epoxy-Al2O3 composites is the backbone structure of the epoxy. In this study, three more epoxies based on diglycidyl ester-terminated liquid-crystalline epoxy (LCE) have been synthesized to draw conclusions regarding the effect of the epoxy backbone structure on the thermal conductivity of epoxy-alumina composites. The synthesized structures were characterized by proton nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared (FT-IR) spectroscopy. Differential scanning calorimetry, thermogravimetric analysis, and optical microscopy were also employed to examine the thermal and optical properties of the synthesized LCEs and the cured composites. All three LCE resins exhibited typical liquid-crystalline behaviors: clear solid crystalline state below the melting temperature ( T m), sharp crystalline melting at T m, and transition to nematic phase above T m with consequent isotropic phase above the isotropic temperature ( T i). The LCE resins displayed distinct nematic liquid-crystalline phase over a wide temperature range and retained liquid-crystalline phase after curing, with high thermal conductivity of the resulting composite. The thermal conductivity values ranged from 3.09 W/m-K to 3.89 W/m-K for LCE-Al2O3 composites with 50 vol.% filler loading. The steric effect played a governing role in the difference. The neat epoxy resin thermal conductivity was obtained as 0.35 W/m-K to 0.49 W/m-K based on analysis using the Agari-Uno model. The results clearly support the objective of this study in that the thermal conductivity of the LCE-containing networks strongly depended on the epoxy backbone structure and the degree of ordering in the cured network.

  19. Synthesis of a Novel Phosphorus-Containing Flame Retardant Curing Agent and Its Application in Epoxy Resins.

    PubMed

    Zhang, Hongkun; Xu, Miaojun; Li, Bin

    2016-03-01

    A novel phosphorus-containing compound diphenyl-(2,5-dihydroxyphenyl)-phosphine oxide defined as DPDHPPO was synthesized and used as flame retardant and curing agent for epoxy resins (EP). The chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 1H, 13C and 31P nuclear magnetic resonance. The flame retardant properties, combusting performances and thermal degradation behaviors of the cured epoxy resins were investigated by limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimeter and thermogravimetric analysis (TGA) tests. The morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The water resistant properties were evaluated by putting the samples into distilled water at 70 degrees C for 168 h. The results revealed that the EP/40 wt% DPDHPPO/60 wt% PDA thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 31.9%. The cone tests results revealed that the incorporation of DPDHPPO efficiently reduced the combustion parameters of epoxy resins thermosets, such as heat release rate (HRR), total heat release (THR) and so on. The TGA results indicated that the introduction of DPDHPPO promoted epoxy resins matrix decomposed ahead of time compared with that of pure EP and led to a higher char yield and thermal stability at high temperature. The morphological structures and analysis of XPS of char residues revealed that DPDHPPO benefited to the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resins materials surface during combustion. After water resistance tests, EP/40 wt% DPDHPPO/60 wt% PDA thermosets still remained excellent flame retardancy, the moisture absorption of epoxy resins thermosets decreased with the increase of DPDHPPO contents in the thermosets due to the existing

  20. Thermal expansion and swelling of cured epoxy resin used in graphite/epoxy composite materials

    NASA Technical Reports Server (NTRS)

    Adamson, M. J.

    1980-01-01

    The paper presents results of experiments in which the thermal expansion and swelling behavior of an epoxy resin system and two graphite/epoxy composite systems exposed to water were measured. It was found that the cured epoxy resin swells by an amount slightly less than the volume of the absorbed water and that the swelling efficiency of the water varies with the moisture content of the polymer. Additionally, the thermal expansion of cured epoxy resin that is saturated with water is observed to be more than twice that of dry resin. Results also indicate that cured resin that is saturated with 7.1% water at 95 C will rapidly increase in moisture content to 8.5% when placed in 1 C water. The mechanism for this phenomenon, termed reverse thermal effect, is described in terms of a slightly modified free-volume theory in conjunction with the theory of polar molecule interaction. Nearly identical behavior was observed in two graphite/epoxy composite systems, thus establishing that this behavior may be common to all cured epoxy resins.

  1. Microcracking in Graphite-Epoxy Composites

    DTIC Science & Technology

    1980-09-01

    ply Pabric 350 -100 to -320 Kirlin/ Pynchon GY 70/X30 (0/45190/135)s 250 -170 General Dynamics/Convair Division CY 70/934 0. 350 -16 Aerospace...and Glass Matrices," J. Mat. Sci. 7, 676-681 (1972). 17. R. L. Kirlin and G. E. Pynchon , "Dimensional Stability Investigation - Graphite/Epoxy Truss

  2. Polymeric Additives For Graphite/Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Nir, Z.

    1990-01-01

    Report describes experimental studies of properties of several graphite/epoxy composites containing polymeric additives as flexibilizing or toughening agents. Emphasizes effects of brominated polymeric additives (BPA's) with or without carboxy-terminated butadiene acrylonitrile rubber. Reviews effects of individual and combined additives on fracture toughnesses, environmental stabilities, hot/wet strengths, thermomechanical behaviors, and other mechanical properties of composites.

  3. Atmospheric corrosion and epoxy-coated reinforcement

    SciTech Connect

    Wheat, H.G.

    1998-12-31

    Atmospheric corrosion can have a tremendous effect on the ability of epoxy-coated reinforcement to maintain its effectiveness. Corrosive conditions can result in the coating becoming brittle and more susceptible to damage from handling. Atmospheric conditions can also enhance localized corrosion at holidays on the bars. Efforts to minimize these effects will be discussed.

  4. Thermal modeling of an epoxy encapsulation process

    SciTech Connect

    Baca, R.G.; Schutt, J.A.

    1991-01-01

    The encapsulation of components is a widely used process at Sandia National Laboratories for packaging components to withstand structural loads. Epoxy encapsulants are also used for their outstanding dielectric strength characteristics. The production of high voltage assemblies requires the encapsulation of ceramic and electrical components (such as transformers). Separation of the encapsulant from internal contact surfaces or voids within the encapsulant itself in regions near the mold base have caused high voltage breakdown failures during production testing. In order to understand the failure mechanisms, a methodology was developed to predict both the thermal response and gel front progression of the epoxy the encapsulation process. A thermal model constructed with PATRAN Plus (1) and solved with the P/THERMAL (2) analysis system was used to predict the thermal response of the encapsulant. This paper discusses the incorporation of an Arrhenius kinetics model into Q/TRAN (2) to model the complex volumetric heat generation of the epoxy during the encapsulation process. As the epoxy begins to cure, it generates heat and shrinks. The total cure time of the encapsulant (transformation from a viscous liquid to solid) is dependent on both the initial temperature and the entire temperature history. Because the rate of cure is temperature dependent, the cure rate accelerates with a temperature increase and, likewise, the cure rate is quenched if the temperature is reduced. The temperature and conversion predictions compared well against experimental data. The thermal simulation results were used to modify the temperature cure process of the encapsulant and improve production yields.

  5. Epoxy resins produce improved plastic scintillators

    NASA Technical Reports Server (NTRS)

    Markley, F. W.

    1967-01-01

    Plastic scintillator produced by the substitution of epoxy resins for the commonly used polystyrene is easy to cast, stable at room temperature, and has the desirable properties of a thermoset or cross-linked system. Such scintillators can be immersed directly in strong solvents, an advantage in many chemical and biological experiments.

  6. Reduced sensitizing capacity of epoxy resin systems: a structure-activity relationship study.

    PubMed

    Niklasson, Ida B; Broo, Kerstin; Jonsson, Charlotte; Luthman, Kristina; Karlberg, Ann-Therese

    2009-11-01

    Epoxy resins can be prepared from numerous chemical compositions. Until recently, alternatives to epoxy resins based on diglycidyl ethers of bisphenol A (DGEBA) or bisphenol F (DGEBF) monomers have not received commercial interest, but are presently doing so, as epoxy resins with various properties are desired. Epoxy resin systems are known to cause allergic contact dermatitis because of contents of uncured monomers, reactive diluents, and hardeners. Reactive diluents, for example, glycidyl ethers, which also contain epoxide moieties, are added to reduce viscosity and improve polymerization. We have investigated the contact allergenic properties of a series of six analogues to phenyl glycidyl ether (PGE), all with similar basic structures but with varying carbon chain lengths and degrees of saturation. The chemical reactivity of the compounds in the test series toward the hexapeptide H-Pro-His-Cys-Lys-Arg-Met-OH was investigated. All epoxides were shown to bind covalently to both cysteine and proline residues. The percent depletion of nonreacted peptide was also studied resulting in 88% depletion when using PGE and 46% when using butyl glycidyl ether (5) at the same time point, thus revealing a large difference between the fastest and the slowest reacting epoxide. The skin sensitization potencies of the epoxides using the murine local lymph node assay (LLNA) were evaluated in relation to the observed physicochemical and reactivity properties. To enable determination of statistical significance between structurally closely related compounds, a nonpooled LLNA was performed. It was found that the compounds investigated ranged from strong to weak sensitizers, congruent with the reactivity data, indicating that even small changes in chemical structure result in significant differences in sensitizing capacity.

  7. New structure of diamine curing agent for epoxy resins with self-restoration ability: Synthesis and spectroscopy characterization

    NASA Astrophysics Data System (ADS)

    Raimondo, Marialuigia; Guadagno, Liberata; Naddeo, Carlo; Longo, Pasquale; Mariconda, Annaluisa; Agovino, Anna

    2017-02-01

    The development of smart materials in aeronautical structures consisting of compounds based on epoxy resins having self-repair capability has been hampered by some criticalities. One of the main critical points is related to the impossibility to use primary amines (e.g.: 4,4‧-diaminodiphenyl sulfone, DDS) as hardeners, because they can poison the catalyst responsible for the healing mechanisms. In this paper, the synthesis, characterization and some tests of applicability of a new hardener, the tetramethylated diaminodiphenyl sulfone (tm-DDS), are shown. The tm-DDS is able to rapidly react with epoxy resin, giving a composite material having some characteristics significantly better than composites hardened with different tertiary amines. The new hardener is able to increase the glass transition temperature (Tg) of about 90 °C with respect to the more common hardener, ancamine K54, already used in self-healing epoxy formulations.

  8. Quantitation of buried contamination by use of solvents. Part 1: Solvent degradation of amine cured epoxy resins

    NASA Technical Reports Server (NTRS)

    Rheineck, A. E.; Heskin, R. A.; Hill, L. W.

    1972-01-01

    The solubility and/or swelling of cured epoxy resins was studied using the solubility parameter method. Determination of solubility parameters were found in order to select solvents for solvent-assisted degradation of cured epoxy polymers used in spacecraft. A method for improving recovery of seeded spores is suggested for assay of buried contaminants. Three commercial epoxy resins were cured using four different alkyl amines. For each resin-amine combination, three levels of amine were used, corresponding to 1/3, 2/3, and all of the amine required to react with the oxirane groups of the resin. The solubility parameters of the 36 resulting model compounds were determined in poorly and moderately hydrogen-bonded solvents. No strongly hydrogen-bonded solvents caused dissolution or swelling. The tolerance of cured resins is discussed in terms of polymer structure.

  9. Investigations of toughening mechanisms of epoxy resins

    NASA Technical Reports Server (NTRS)

    Koenig, T.

    1986-01-01

    Composite material technology was applied to the solid rocket booster by the development of a carbon filament-epoxy resin case which yields a net increase of 4000 lbs. in payload in the shuttle. The question of reusability of the new composite tanks has not yet been answered and will depend on the toughness of the matrix resin. The present study was aimed at providing conditions whereby test specimens of the epoxy resin (EPON/85) and curing agents of systematically varied structures could be produced in a controlled manner. Three sets of conditions were found that might allow the isolation of the structural effects on toughness from the cure effects. The kinetic methods leading to the determination of these conditions are described.

  10. Cycloaliphatic epoxy resin coating for capillary electrophoresis.

    PubMed

    Shah, Roopa S; Wang, Qinggang; Lee, Milton L

    2002-04-05

    Coating the interior surface of a fused-silica capillary with a polymeric material has long been used in capillary electrophoresis (CE) to reduce or eliminate electroosmotic flow and suppress adsorption. A cycloaliphatic epoxide-based resin was bonded to silane treated capillaries and crosslinked with a curing agent. The epoxy resin coating significantly reduced electroosmotic flow over a pH range of 3-10. This coating was sufficiently hydrophilic to suppress protein adsorption. The epoxy resin coated capillary was used to separate several acidic and basic proteins and peptides. Separation efficiencies greater than 400,000 theoretical plates were achieved. The relative standard deviations in migration times for proteins were <0.8%. Speed and simplicity are important advantages of the coating procedure compared to other published coating methods.

  11. Microwave limb sounder, graphite epoxy support structure

    NASA Technical Reports Server (NTRS)

    Pynchon, G.

    1980-01-01

    The manufacturing and processing procedures which were used to fabricate a precision graphite/epoxy support structure for a spherical microwave reflecting surface are described. The structure was made fromm GY-70/930 ultra high modulus graphite prepreg, laminated to achieve an isotropic in plane thermal expansion of less than + or - 0.1 PPM/F. The structure was hand assembled to match the interface of the reflective surface, which was an array of 18 flexure supported, aluminum, spherically contoured tiles. Structural adhesives were used in the final assembly to bond the elements into their final configuration. A eutectic metal coating was applied to the composite surface to reduce dimensional instabilities arising from changes in the composite epoxy moisture content due to environmental effects. Basic materials properties data are reported and the results of a finite element structural analysis are referenced.

  12. Biobased Epoxy Nanocomposites Derived from Lignin-Based Monomers.

    PubMed

    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.

  13. Morphology development of rubber-modified epoxy thermosets

    SciTech Connect

    Kwon, O.; Ward, T.C.

    1996-12-31

    Epoxy thermosets have been widely used as high performance adhesives and matrix resins for composites due to their outstanding mechanical and thermal properties, such as high modulus and tensile strength, high glass transition temperature, high thermal stability, and moisture resistance. Incorporation of a secondary rubbery phase into the glassy epoxy matrix can improve impact and fracture toughness of epoxy thermosets without sacrificing the other desirable properties of the neat epoxy thermoset. During the curing process, the initial homogeneous solution of epoxy resin-curing agent-rubber generally forms rubber-rich and epoxy-rich phases by a phase separation process which is arrested by gelation or vitrification. The final morphology developed by the cure depends on relative rates of cure reaction and phase separation. Cure conditions and the initial rubber composition control the morphology of the system and thus control the mechanical properties of the system.

  14. Epoxy thermoset networks derived from vegetable oils and their blends

    NASA Astrophysics Data System (ADS)

    Ryu, Chang; Ravalli, Matthew

    2015-03-01

    Epoxidized vegetable oils (EVOs), such as epoxidized soybean oil and linseed oils were prepared by the partial oxidation of the unsaturated double bonds in vegetable oils and used as monomers for preparing epoxy thermoset materials based on the cationic polymerization. These EVOs have been used to prepare epoxy thermosets of different network densities by cationic polymerization using onium salt catalyst. The crosslinked epoxy thermosets provide an ideal platform to study the structure-property-relationships of networked polymers. In particular, rheological studies on the epoxidized vegetable oil thermosets have been performed to measure the molecular weights between crosslinks (Mx) in the epoxy thermosets and to ultimately elucidate the role of functionality of epoxy groups in EVO on the mechanical and thermophysical properties of the epoxy thermoset materials. NSF DMR POLYMERS 1308617.

  15. Mechanism of fatigue failure of clay-epoxy nanocomposites.

    PubMed

    Juwono, Ariadne; Edward, Graham

    2006-12-01

    This work investigates the fatigue behaviour and the mechanism of fatigue failure of an epoxy resin with a dispersion of modified layered silicates in the polymer matrix. The fatigue properties are very important for structural application of nanocomposite materials. Clay-epoxy nanocomposites were successfully synthesized with a commercially available 1-Methylimidazole curing agent. The XRD and TEM findings demonstrated a pattern of clay morphology typically found in nanocomposite systems. The fatigue performance and fatigue failure mechanism of the clay-epoxy materials were studied under repetitive bending loads. The results showed that the fatigue life of filled epoxy improved significantly at strain amplitudes below a threshold value. The E-SEM observations of the epoxy and the clay-epoxy fracture surfaces showed different patterns. In conclusion, the addition of silicate strongly determines the fracture mechanism and enhances the fatigue performance.

  16. Glass/Epoxy Door Panel for Automobiles

    NASA Technical Reports Server (NTRS)

    Bauer, J. L. JR.

    1985-01-01

    Lightweight panel cost-effective. Integrally-molded intrusion strap key feature of composite outer door panel. Strap replaces bulky and heavy steel instrusion beam of conventional door. Standard steel inner panel used for demonstration purposes. Door redesigned to exploit advantages of composite outer panel thinner. Outer panel for automobilie door, made of glass/epoxy composite material, lighter than conventional steel door panel, meets same strength requirements, and less expensive.

  17. Metallic Coatings for Graphite/Epoxy Composites

    DTIC Science & Technology

    1980-08-01

    Aero Structures Dept -. Radomes Section B-2 DISTRIBUTION (cont.)K COPIES * U. S. Army Air Mobility R&D Laboratory 1II 1Fort Eustis, VA ATTN: SAVDL-EU...for graphite/epoxy laminated aircraft structures were developed to provide protection against moisture penetration, electro’)- magnetic interference...performance * aircraft. Utilization of advanced composite structures to their design limits neces- sitates the protection of these structures against

  18. Epoxy Pipelining Composition and Method of Manufacture.

    DTIC Science & Technology

    1994-12-14

    corrosion and erosion. The pipelining 10 composition forms a barrier which prevents the leaching of, for example, metals from 11 pipes. This invention...invention, 13 more particularly, relates to an epoxy resin/curing agent corrosion -resistant network 14 pipelining composition suitable for the in...hydrochloric acid, hydrogen sulfide, sulfuric acid, and other corrosive 21 products of bacterial activity. Excessively high flow rates also erode the metal

  19. High Temperature Epoxy Nanocomposites for Aerospace Applications

    DTIC Science & Technology

    2009-06-10

    weak molecular interaction between non-polar alkyl chain of ammonium modified clay and polar group of epoxy resin. This was confirmed by the X- ray...polymer matrix. Several functionalized imidazolium clays , functionalized anionic clays , and silylated apophylites were synthesized and characterized by...XRD and TGA. Thermal studies of functionalized clay have shown that the onset decomposition temperature of imidazolium functionalized clay (>325oC

  20. Safe epoxy encapsulant for high voltage magnetics

    SciTech Connect

    Sanchez, R.O.; Archer, W.E.

    1998-01-01

    This paper describes the use of Formula 456, an aliphatic amine cured epoxy for impregnating coils and high voltage transformers. Sandia has evaluated a number of MDA-free epoxy encapsulants which relied on either anhydride or other aromatic amine curing agents. The use of aliphatic amine curing agents was more recently evaluated and has resulted in the definition of Formula 456 resin. Methylene dianiline (MDA) has been used for more than 20 years as the curing agent for various epoxy formulations throughout the Department of Energy and much of industry. Sandia National Laboratories began the process of replacing MDA with other formulations because of regulations imposed by OSHA on the use of MDA. OSHA has regulated MDA because it is a suspect carcinogen. Typically the elimination of OSHA-regulated materials provides a rare opportunity to qualify new formulations in a range of demanding applications. It was important to take full advantage of that opportunity, although the associated materials qualification effort was costly. Small high voltage transformers are one of those demanding applications. The successful implementation of the new formulation for high reliability transformers will be described. The test results that demonstrate the parts are qualified for use in DOE weapon systems will be presented.

  1. Evaluation of Coatings for FR-4 Fiberglass Epoxy Composite Probes

    DTIC Science & Technology

    2014-01-01

    The probe is fabricated from a composite material ( FR -4) composed of woven fiberglass cloth with a flame-resistant epoxy resin binder. FR -4 is a...Evaluation of Coatings for FR -4 Fiberglass Epoxy Composite Probes by Faye R. Toulan, David P. Flanagan, John J. La Scala, and Daniel M. De...5069 ARL-TR-6771 January 2014 Evaluation of Coatings for FR -4 Fiberglass Epoxy Composite Probes Faye R. Toulan Dynamic Science, Inc

  2. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    NASA Technical Reports Server (NTRS)

    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.

  3. Antidiarrheal Thymol Derivatives from Ageratina glabrata. Structure and Absolute Configuration of 10-Benzoyloxy-8,9-epoxy-6-hydroxythymol Isobutyrate.

    PubMed

    Bustos-Brito, Celia; Vázquez-Heredia, Valeria J; Calzada, Fernando; Yépez-Mulia, Lilian; Calderón, José S; Hernández-Ortega, Simón; Esquivel, Baldomero; García-Hernández, Normand; Quijano, Leovigildo

    2016-09-12

    Chemical investigation of the leaves from Ageratina glabrata yielded four new thymol derivatives, namely: 10-benzoyloxy-8,9-dehydro-6-hydroxythymol isobutyrate (4), 10-benzoyloxy-8,9-dehydrothymol (5), 10-benzoyloxythymol (6) and 10-benzoyloxy-6,8-dihydroxy-9-isobutyryl-oxythymol (7). In addition, (8S)-10-benzoyloxy-8,9-epoxy-6-hydroxythymol isobutyrate (1), together with other two already known thymol derivatives identified as 10-benzoyloxy-8,9-epoxy-6-methoxythymol isobutyrate (2) and 10-benzoyloxy-8,9-epoxythymol isobutyrate (3) were also obtained. In this paper, we report the structures and complete assignments of the ¹H and (13)C-NMR data of compounds 1-7, and the absolute configuration for compound 1, unambiguously established by single crystal X-ray diffraction, and evaluation of the Flack parameter. The in vitro antiprotozoal assay showed that compound 1 and its derivative 1a were the most potent antiamoebic and antigiardial compounds. Both compounds showed selectivity and good antiamoebic activity comparable to emetine and metronidazole, respectively, two antiprotozoal drugs used as positive controls. In relation to anti-propulsive effect, compound 1 and 1a showed inhibitory activity, with activities comparable to quercetin and compound 9, two natural antipropulsive compounds used as positive controls. These data suggest that compound 1 may play an important role in antidiarrheal properties of Ageratina glabrata.

  4. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    SciTech Connect

    Brown, Eric N; Rae, Philip J; Dattelbaum, Dana M; Stahl, David B

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  5. Cobalt Ions Improve the Strength of Epoxy Resins

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, A. K.

    1986-01-01

    Technique developed for improving mechanical strength of epoxy resins by adding cobalt ions in form of tris(acetylacetonato)cobalt (III) complex. Solid cast disks prepared from cobalt ion-containing epoxy resins tested for flexural strength and stiffness. Incorporation of cobalt ions into epoxies increased flexural strength of resins by 10 to 95 percent. Suitable resins for this technique include any liquid or solid TGMDA resins. Improved epoxy formulation proves useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft.

  6. Toughened epoxy resin system and a method thereof

    DOEpatents

    Janke, Christopher J.; Dorsey, George F.; Havens, Stephen J.; Lopata, Vincent J.

    1998-01-01

    Mixtures of epoxy resins with cationic initiators are curable under high energy ionizing radiation such as electron beam radiation, X-ray radiation, and gamma radiation. The composition of this process consists of an epoxy resin, a cationic initiator such as a diaryliodonium or triarylsulfonium salt of specific anions, and a toughening agent such as a thermoplastic, hydroxy-containing thermoplastic oligomer, epoxy-containing thermoplastic oligomer, reactive flexibilizer, rubber, elastomer, or mixture thereof. Cured compositions have high glass transition temperatures, good mechanical properties, and good toughness. These properties are comparable to those of similar thermally cured epoxies.

  7. Toughened epoxy resin system and a method thereof

    DOEpatents

    Janke, C.J.; Dorsey, G.F.; Havens, S.J.; Lopata, V.J.

    1998-03-10

    Mixtures of epoxy resins with cationic initiators are curable under high energy ionizing radiation such as electron beam radiation, X-ray radiation, and gamma radiation. The composition of this process consists of an epoxy resin, a cationic initiator such as a diaryliodonium or triarylsulfonium salt of specific anions, and a toughening agent such as a thermoplastic, hydroxy-containing thermoplastic oligomer, epoxy-containing thermoplastic oligomer, reactive flexibilizer, rubber, elastomer, or mixture thereof. Cured compositions have high glass transition temperatures, good mechanical properties, and good toughness. These properties are comparable to those of similar thermally cured epoxies.

  8. Space environmental effects on graphite-epoxy compressive properties and epoxy tensile properties

    NASA Technical Reports Server (NTRS)

    Fox, Derek J.; Sykes, George F., Jr.; Herakovich, Carl T.

    1987-01-01

    This study characterizes the effects of electron radiation and temperature on a graphite-epoxy composite material. Compressive properties of the T300/934 material system were obtained at -250 F (-157 C), room temperature, and 250 F (121 C). Tensile specimens of the Fiberite 934 epoxy resin were fabricated and tested at room temperature and 250 F (121 C). Testing was conducted in the baseline (nonirradiated) and irradiated conditions. The radiation exposure was designed to simulate 30 year, worst-case exposure in geosynchronous Earth orbit. Mechanical properties tended to degrade at elevated temperature and improve at cryogenic temperature. Irradiation generally degraded properties at all temperatures.

  9. The aba mutant of Arabidopsis thaliana is impaired in epoxy-carotenoid biosynthesis

    SciTech Connect

    Rock, C.D.; Zeevaart, J.A.D. )

    1991-09-01

    The three mutant alleles of the ABA locus of Arabidopsis thaliana result in plants that are deficient in the plant growth regulator abscisic acid (ABA). The authors have used {sup 18}O{sub 2} to label ABA in water-stressed leaves of mutant and wild-type Arabidopsis. Analysis by selected ion monitoring and tandem mass spectrometry of ({sup 18}O)ABA and its catabolites, phaseic acid and ABA-glucose ester ({beta}-D-glucopyranosyl abscisate), indicates that the aba genotypes are impaired in ABA biosynthesis and have a small ABA precursor pool of compounds that contain oxygens on the rings, presumably oxygenated carotenoids (xanthophylls). Quantitation of the carotenoids form mutant and wild-type leaves establishes that the aba alleles cause a deficiency of the epoxy-carotenoids violaxanthin and neoxanthin and an accumulation of their biosynthetic precursor, zeaxanthin. These results provide evidence that ABA is synthesized by oxidative cleavage of epoxy-carotenoids (the indirect pathway). Furthermore the carotenoid mutant they describe undergoes normal greening. Thus the aba alleles provide an opportunity to study the physiological roles of epoxy-carotenoids in photosynthesis in a higher plants.

  10. Optical characteristics of the Eu 3+- β-diketonate complex doped into epoxy resin

    NASA Astrophysics Data System (ADS)

    Parra, Duclerc F.; Mucciolo, Adriana; Brito, Hermi F.; Thompson, Larry C.

    2003-02-01

    Preparation of epoxy resins doped with triaquatris(acetylacetonate)europium(III) [Eu(ACAC) 3(H 2O) 3] at 1%, 5%, 10% and 15% and their luminescent properties in the solid state are reported. In addition, the catalytic properties of samples doped with [Eu(TTA) 3(H 2O) 2] (I) and [Eu(ACAC) 3(H 2O) 3] (II) have been compared to that of a physical mixture of epoxy resin containing dicyandiamide (III) in the DSC curing process under heating. It was verified that the product (I) was cured under the same conditions as (III), but that product (II) was not cured. The compounds were characterized by elemental analysis, thermogravimetry (TG), differential scanning calorimetry (DSC) and infrared spectroscopy. The emission spectra of the Eu 3+-ACAC complex doped in the epoxy resin recorded at 298 and 77 K exhibited the characteristic bands arising from the 5D0→ 7FJ transitions ( J=0-4). The experimental intensity parameter, Ω 2, indicated that the Eu 3+ ion in the precursor complex is in a more polarizable chemical environment than in the doped system. The emitter 5D0 level lifetimes for doped samples (1%, 5%, 10% and 15%) show the luminescence decay curve profiles as single exponentials. The Eu-doped system containing the TTA ligand presented a higher emission quantum efficiency than that with ACAC. The emission quantum efficiencies ( η) are also discussed.

  11. Organo-modified bentonites as new flame retardant fillers in epoxy resin nanocomposites

    NASA Astrophysics Data System (ADS)

    Benelli, Tiziana; D'Angelo, Emanuele; Mazzocchetti, Laura; Saraga, Federico; Sambri, Letizia; Franchini, Mauro Comes; Giorgini, Loris

    2016-05-01

    The present work deals with two organophilic bentonites, based on nitrogen-containing compounds: these organoclays were synthesized via an ion exchange process starting from pristine bentonite with 6-(4-butylphenyl)-1,3,5-triazine-2,4-diamine (BFTDA) and 11-amino-N-(pyridine-2yl)undecanamide (APUA) and then used for the production of epoxy-based flame retardant nanocomposites. The amount of organic modifier in the organoclays Bento-BFTDA and Bento-APUA was determined with a TGA analysis and is around 0.4mmol/g for both samples. The effect of the organoclays on a commercial epoxy resin nanocomposite's thermo-mechanical and flammability properties was investigated. Composites containing 3wt% and 5wt% of the nanofillers were prepared by solventless addition of each organoclay to the epoxy resin, followed by further addition of the hardener component. For the sake of comparison a similar nanocomposite with the plain unmodified bentonite was produced in similar condition. The nanocomposites's thermo-mechanical properties of all the produced samples were measured and they resulted slightly improved or practically unaffected. On the contrary, when the flame behaviour was assessed in the cone-calorimeter, an encouraging decrease of 17% in the peak heat released rate (pHRR) was obtained at 3wt% loading level with Bento-APUA. This is a promising result, assessing that the APUA modified organoclay might act as flame retardant.

  12. Thermal Expansion and Swelling of Cured Epoxy Resin Used in Graphite/Epoxy Composite

    NASA Technical Reports Server (NTRS)

    Adamson, M. J.

    1979-01-01

    The thermal expansion and swelling of resin material as influenced by variations in temperature during moisture absorption is discussed. Comparison measurements using composites constructed of graphite fibers and each of two epoxy resin matrices are included. Polymer theory relative to these findings is discussed and modifications are proposed.

  13. Alcohol-Sensitive Epoxy Formulations for Temporary or Repairable Embedment

    DTIC Science & Technology

    1976-06-01

    10,000 and 40,000 mol wt, respectively A conformal coating epoxy, bisphenol-A type epoxy cured with polyamide and others; toluene as solvent; conforming...COMPOSITES BR ATTN LNE, ELASTOMERS & COATINGS BR 25 DISTRIBUTION (Cont’d) HARRY DIAMOND LABORATORIES ATTN MCGREGOR, THOMAS, COL, COMMANDING

  14. Respiratory effects of exposure of shipyard workers to epoxy paints.

    PubMed Central

    Rempel, D; Jones, J; Atterbury, M; Balmes, J

    1991-01-01

    Epoxy resin systems have been associated with occupational asthma in several case reports, but medical publications contain little on the potential adverse respiratory effects of these chemicals in exposed worker populations. To further evaluate the association of workplace exposure to epoxy paints and respiratory dysfunction, the cross workshift changes in pulmonary function and symptoms of 32 shipyard painters exposed to epoxy paints were compared with 28 shipyard painters not exposed to epoxy paints. The prevalence of lower respiratory tract symptoms was significantly higher among painters exposed to epoxy paints compared with controls. Among exposed painters the mean cross workshift change in forced expiratory volume in one second (FEV1) (-3.4%) was greater than the decrement in the non-exposed group (-1.4%). A significant linear relation was seen between % decrement in FEV1 and hours of exposure to epoxy paints. This study suggests that epoxy resin coatings as used by shipyard painters are associated with increased lower respiratory tract symptoms and acute decrements in FEV1. Adequate respiratory protection and medical surveillance programmes should be established in workplaces where exposure to epoxy resin systems occurs. PMID:1954156

  15. A self-crosslinking thermosetting monomer with both epoxy and anhydride groups derived from Tung oil fatty acids: Synthesis and properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A self-crosslinking compound with epoxy groups and anhydride groups (GEMA) has been successfully synthesized from Tung oil fatty acid by reacting with maleic anhydride via the Diels-Alder reaction. GEMA has very good storage stability and can be cured with trace amounts of tertiary amine. This advan...

  16. A self-crosslinking thermosetting monomer with both epoxy and anhydride groups derived from tung oil fatty acids: Synthesis and properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A self-crosslinking compound with epoxy groups and anhydride groups (GEMA) has been successfully synthesized from tung oil fatty acid by reacting with maleic anhydride via the Diels-Alder reaction. GEMA has very good storage stability and could be cured with trace amounts of tertiary amine. This ad...

  17. Room Temperature Curing Epoxy Resin Compositions High Temperature Service Capability for Fiber Reinforced Structures, Adhesives and Sealants.

    DTIC Science & Technology

    1981-06-01

    long chain high molecular weight polyamide , and c) an imidazole compound such as 2 ethyl, 4 methyl imidazole; 2 methyl imidazole or the like. The...aliphatic polyamine was triethylene tetramine and the polyamide General Mills Versamid 840 (see Table 2). A sub- stantial amount of experimental work has...capability of such epoxy resin composi- tions while products such as the aliphatic polyamide can contribute to tough- ness. Also alternatively flexible

  18. Drilling Holes in Graphite/Epoxy

    NASA Technical Reports Server (NTRS)

    Minlionica, Ronald

    1987-01-01

    Relatively long-lived bit produces high-quality holes. Effective combination of cutting-tool design, feed, and speed determined for drilling 3/16-and-1/4-in. (0.48-and 0.65-cm) diameter holes in 0.18 in. (0.46cm) thick GM3013A or equivalent graphite/epoxy corrugated spar without backup material and without coolant. Developed to produce holes in blind areas, optimal techniques yielded holes of high quality, with minimal or acceptable delamination and/or fiber extension on drill-exit side.

  19. Epoxy resin cure. [Phenyl glycidyl ether

    SciTech Connect

    Smith, R.E.; Woodburn, G.L.

    1986-07-01

    The reactions that occur between the model epoxy, phenyl glycidyl ether, and the cure agent dicyandiamide (DICY) have been investigated using nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), gel permeation chromatography (GPC), and high-performance liquid chromatography (HPLC) techniques. It is shown that the reaction at 130/sup 0/C requires 90 min for completion when catalyzed by boron trifluoride monoethyl amine (BF/sub 3/-MEA). At least three major products are formed. The identity of these products is based on previously published spectroscopic data. 3 refs., 5 figs.

  20. Compressive response of Kevlar/epoxy composites

    SciTech Connect

    Yeh, J.R.; Teply, J.L.

    1988-03-01

    A mathematical model is developed from the principle of minimum potential energy to determine the longitudinal compressive response of unidirectional fiber composites. A theoretical study based on this model is conducted to assess the influence of local fiber misalignment and the nonlinear shear deformation of the matrix. Numerical results are compared with experiments to verify this study; it appears that the predicted compressive response coincides well with experimental results. It is also shown that the compressive strength of Kevlar/epoxy is dominated by local shear failure. 12 references.

  1. Designing of epoxy resin systems for cryogenic use

    NASA Astrophysics Data System (ADS)

    Ueki, T.; Nishijima, S.; Izumi, Y.

    2005-02-01

    The mechanical and thermal properties of several types of epoxy systems were designed based on the chemical structure, network structure and morphology aiming at cryogenic application. In this research di-epoxies or multifunctional epoxies were cured by several kinds of hardeners such as anhydride, amine or phenol and were blended with polycarbonate, carboxyl-terminated butadiene acrylonitrile copolymer or phenoxy. The mechanical properties and thermal properties of these cured epoxies were measured at room and liquid nitrogen temperature. It was found that the two-dimensional network structured linear polymer shows high performance even at cryogenic temperature. It was concluded that the controls of the structures are very important to optimize epoxy systems for cryogenic application.

  2. Cationic cure kinetics of a polyoxometalate loaded epoxy nanocomposite

    SciTech Connect

    Anderson, Benjamin J.

    2012-08-06

    The reaction cure kinetics of a novel polyoxometalate (POM) loaded epoxy nanocomposite is described. The POM is dispersed in the epoxy resin up to volume fractions of 0.1. Differential scanning calorimetry measurements show the cure of the epoxy resin to be sensitive to the POM loading. A kinetics study of the cure exotherm confirms that POM acts as a catalyst promoting cationic homopolymerization of the epoxy resin. The cure reaction is shown to propagate through two cure regimes. A fast cure at short time is shown to be propagation by the activated chain end (ACE) mechanism. A slow cure at long time is shown to be propagation by the activated monomer (AM) mechanism. The activation energies for the fast and slow cure regimes agree well with other epoxy based systems that have been confirmed to propagate by the ACE and AM mechanisms.

  3. Determination of interlaminar shear strength for glass/epoxy and carbon/epoxy laminates at impact rates of strain

    NASA Astrophysics Data System (ADS)

    Harding, J.; Li, Y. L.

    A new technique is proposed for determining the interlaminar shear strength of fiber-reinforced polymer matrix composites using a double-lap shear specimen in which failure occurs on a predetermined plane. by using different ply layups in the double-lap shear specimen, the effect of loading rate on the interfacial shear strength is determined for (1) two plain-weave carbon/epoxy plies, (2) two plain-weave glass/epoxy plies, and (3) a plain-weave carbon/epoxy ply and a plain-weave carbon/epoxy ply and a plain-weave glass/epoxy ply. An increase in loading rate of about six orders of magnitude is found to raise the average value of the shear stress on the failure plane by about 70 percent for the carbon/carbon and glass/glass interfaces and by about 50 percent for the hybrid carbon/glass interface.

  4. Biaryl synthesis by ring-opening Friedel-Crafts arylation of 1,4-epoxy-1,4-dihydronaphthalenes catalyzed by iron trichloride.

    PubMed

    Sawama, Yoshinari; Asai, Shota; Kawajiri, Takahiro; Monguchi, Yasunari; Sajiki, Hironao

    2015-01-26

    Biaryl and heterobiaryl compounds are important frameworks across a range of fields including pharmaceutical and functional material chemistries. We have accomplished the efficient synthesis of various naphthalene-linked arenes and heteroarenes as biaryls and heterobiaryls by the FeCl3 -catalyzed Friedel-Crafts reactions accompanied by the ring-opening of the 1,4-epoxy moiety of 1,4-epoxy-1,4-dihydronaphthalenes. Especially, it is noteworthy that 1-silylated substrates were regioselectively transformed to the 3-aryl-1-silylnaphthalenes and the double Friedel-Crafts reactions using thiophene derivatives could directly produce the corresponding bis-naphthlated thiophene derivatives.

  5. Ultrasonic mixing of epoxy curing agents

    NASA Technical Reports Server (NTRS)

    Hodges, W. T.; St.clair, T. L.

    1983-01-01

    A new technique for mixing solid curing agents into liquid epoxy resins using ultrasonic energy was developed. This procedure allows standard curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminobenzophenone (4,4 prime-DABP) (242 C) to be mixed without premature curing. Four aromatic diamines were ultrasonically blended into MY-720 epoxy resin. These were 4,4 prime-DDS; 3,3 prime-DDA; 4,4 prime-DABP and 3,3 prime-DABP. Unfilled moldings were cast and cured for each system and their physical and mechanical properties compared.

  6. Bolted joints in graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1976-01-01

    All-graphite/epoxy laminates and hybrid graphite-glass/epoxy laminates were tested. The tests encompassed a range of geometries for each laminate pattern to cover the three basic failure modes - net section tension failure through the bolt hole, bearing and shearout. Static tensile and compressive loads were applied. A constant bolt diameter of 6.35 mm (0.25 in.) was used in the tests. The interaction of stress concentrations associated with multi-row bolted joints was investigated by testing single- and double-row bolted joints and open-hole specimens in tension. For tension loading, linear interaction was found to exist between the bearing stress reacted at a given bolt hole and the remaining tension stress running by that hole to be reacted elsewhere. The interaction under compressive loading was found to be non-linear. Comparative tests were run using single-lap bolted joints and double-lap joints with pin connection. Both of these joint types exhibited lower strengths than were demonstrated by the corresponding double-lap joints. The analysis methods developed here for single bolt joints are shown to be capable of predicting the behavior of multi-row joints.

  7. Epoxy Crosslinked Silica Aerogels (X-Aerogels)

    NASA Technical Reports Server (NTRS)

    fabrizio, Eve; Ilhan, Faysal; Meador, Mary Ann; Johnston, Chris; Leventis, Nicholas

    2004-01-01

    NASA is interested in the development of strong lightweight materials for the dual role of thermal insulator and structural component for space vehicles; freeing more weight for useful payloads. Aerogels are very-low density materials (0.010 to 0.5 g/cc) that, due to high porosity (meso- and microporosity), can be, depending on the chemical nature of the network, ideal thermal insulators (thermal conductivity approx. 15 mW/mK). However, aerogels are extremely fragile. For practical application of aerogels, one must increase strength without compromising the physical properties attributed to low density. This has been achieved by templated growth of an epoxy polymer layer that crosslinks the "pearl necklace" network of nanoparticles: the framework of a typical silica aerogel. The requirement for conformal accumulation of the epoxy crosslinker is reaction both with the surface of silica and with itself. After cross-linking, the strength of a typical aerogel monolith increases by a factor of 200, in the expense of only a 2-fold increase in density. Strength is increased further by coupling residual unreacted epoxides with diamine.

  8. Electrical properties of epoxy/silver nanocomposites

    NASA Astrophysics Data System (ADS)

    Gonon, P.; Boudefel, A.

    2006-01-01

    We investigated the electrical properties of nanocomposites made of epoxy resin filled with 70-nm-sized silver particles. These composites were studied for the fabrication of integrated capacitors in electronics packaging. The dc conductivity was studied as a function of the filler concentration and as a function of temperature. We also studied the ac conductivity and the permittivity in the 10-1-105 Hz range as a function of the filler concentration. Experimental properties were analyzed using standard percolation theories. The dc conductivity varies as (φ-φc)t, where φ is the filler concentration, φc is the percolation threshold, and t is the dc critical exponent. A very low percolation threshold is obtained (φc=1%) which is believed to be related to a segregated distribution of the fillers in the epoxy matrix. We also measured a very high dc critical exponent (t=5) probably related to the interparticle electrical contact. A universal scaling law is observed for σ(ω) and ɛ(ω). Above a cutoff frequency (ωc, which scales with the dc conductivity as ωc~σdcq) the conductivity and the permittivity follow the universal power laws (σ~ωu and V~ω-v) with critical exponents taking nonstandard values (q=0.83-0.98, u=0.79, and v=0.03).

  9. Fracture behavior of nano-scale rubber-modified epoxies

    NASA Astrophysics Data System (ADS)

    Bacigalupo, Lauren N.

    The primary focus of the first portion of this study is to compare physical and mechanical properties of a model epoxy that has been toughened with one of three different types of rubber-based modifier: a traditional telechelic oligomer (phase separates into micro-size particles), a core-shell latex particle (preformed nano-scale particles) and a triblock copolymer (self-assembles into nano-scale particles). The effect of modifier content on the physical properties of the matrix was determined using several thermal analysis methods, which provided insight into any inherent alterations of the epoxy matrix. Although the primary objective is to study the role of particle size on the fracture toughness, stiffness and strength were also determined since these properties are often reduced in rubber-toughened epoxies. It was found that since the CSR- and SBM-modified epoxies are composed of less rubber, thermal and mechanical properties of the epoxy were better maintained. In order to better understand the fracture behavior and mechanisms of the three types of rubber particles utilized in this study, extensive microscopy analysis was conducted. Scanning transmission electron microscopy (STEM) was used to quantify the volume fraction of particles, transmission optical microscopy (TOM) was used to determine plastic damage zone size, and scanning electron microscopy (SEM) was used to assess void growth in the plastic zone after fracture. By quantifying these characteristics, it was then possible to model the plastic damage zone size as well as the fracture toughness to elucidate the behavior of the rubber-modified epoxies. It was found that localized shear yielding and matrix void growth are the active toughening mechanisms in all rubber-modified epoxies in this study, however, matrix void growth was more prevalent. The second portion of this study investigated the use of three acrylate-based triblocks and four acrylate-based diblocks to modify a model epoxy system. By

  10. Progress toward Making Epoxy/Carbon-Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Tiano, Thomas; Roylance, Margaret; Gassner, John; Kyle, William

    2008-01-01

    A modicum of progress has been made in an effort to exploit single-walled carbon nanotubes as fibers in epoxy-matrix/fiber composite materials. Two main obstacles to such use of carbon nanotubes are the following: (1) bare nanotubes are not soluble in epoxy resins and so they tend to agglomerate instead of becoming dispersed as desired; and (2) because of lack of affinity between nanotubes and epoxy matrices, there is insufficient transfer of mechanical loads between the nanotubes and the matrices. Part of the effort reported here was oriented toward (1) functionalization of single-walled carbon nanotubes with methyl methacrylate (MMA) to increase their dispersability in epoxy resins and increase transfer of mechanical loads and (2) ultrasonic dispersion of the functionalized nanotubes in tetrahydrofuran, which was used as an auxiliary solvent to aid in dispersing the functionalized nanotubes into a epoxy resin. In another part of this effort, poly(styrene sulfonic acid) was used as the dispersant and water as the auxiliary solvent. In one experiment, the strength of composite of epoxy with MMA-functionalized-nanotubes was found to be 29 percent greater than that of a similar composite of epoxy with the same proportion of untreated nanotubes.

  11. Measurement of residual strains in boron-epoxy and glass-epoxy laminates

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Liber, T.; Chamis, C. C.

    1975-01-01

    Embedded-strain-gage techniques were developed and used for measuring strains in composite angle-ply laminates during curing and thermal cycling. The specimens were 2.54 by 22.9 cm eight-ply boron-epoxy and S-glass-epoxy laminates. Unidirectional specimens were used for control purposes. Strain readings were corrected for the purely thermal output of the gages obtained from an instrument quartz reference specimen. The strains measured during the cooling part of the curing cycle were in agreement with those recorded during subsequent thermal cycling, indicating that residual stresses induced during curing are primarily caused by differential thermal expansions of the various plies. Restraint strains were computed for the 0-deg and 45-deg plies of the angle-ply laminates tested, and the residual stresses obtained using the anisotropic constitutive relations and taking into account the temperature dependence of stiffnesses and strains.

  12. Tension fatigue of glass/epoxy and graphite/epoxy tapered laminates

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; Obrien, T. Kevin; Salpekar, Satish A.

    1990-01-01

    Symmetric tapered laminates with internally dropped plies were tested with two different layups and two materials, S2/SP250 glass/epoxy and IM6/1827I graphite/epoxy. The specimens were loaded in cyclic tension until they delaminated unstably. Each combination of material and layup had a unique failure mode. Calculated values of strain energy release rate, G, from a finite element analysis model of delamination along the taper, and for delamination from a matrix ply crack, were used with mode I fatigue characterization data from tests of the tested materials to calculate expected delamination onset loads. Calculated values were compared to the experimental results. The comparison showed that when the calculated G was chosen according to the observed delamination failures, the agreement between the calculated and measured delamination onset loads was reasonable for each combination of layup and material.

  13. Experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in shear

    NASA Technical Reports Server (NTRS)

    Weller, T.

    1977-01-01

    The nonlinear/inelastic response under inplane shear of a large variety of graphite-epoxy and boron-epoxy angle-ply laminates was tested. Their strength allowables were obtained and the mechanisms which govern their mode of failure were determined. Two types of specimens for the program were chosen, tested, and evaluated: shear panels stabilized by an aluminum honeycomb core and shear tubes. A modified biaxially compression/tension loaded picture frame was designed and utilized in the test program with the shear panels. The results obtained with this test technique categorically prefer the shear panels, rather than the tubes, for adequate and satisfactory experimental definition of the objectives. Test results indicate the existence of a so-called core-effect which ought to be considered when reducing experimental data for weak in shear laminates.

  14. Viscoelastic Characterization of a Nonlinear, Glass/Epoxy Composite Including the Effects of Damage

    DTIC Science & Technology

    1974-10-01

    Schapery Isothermal creep and recovery tests were conducted on an epoxy resin and a glass fiber-reiiforced composite made from the same bulk resin ...Contracted Notations ... ......... ... 43 2 Ingredients of Shell 58-68R Epoxy Resin [181]. . 9 3 Fiber Content of S-901 Glass/Shell 58-68R Epoxy Resin ...Epoxy Resin .......... ................... 154 i0 Shift Factors, aT, for Shell 58-68R Epoxy Resin .......... ................... 164 11 Shell 58-68R

  15. Cure-dependent Viscoelastic Poisson’s Ratio of Epoxy

    DTIC Science & Technology

    2007-01-26

    Faivre S, Roy LE, Trotignon JP, Verdu J (1996) Mechanical properties of thermosets. Part I. Tensile properties of an anhydride cured epoxy . J Mater...Experimental Mechanics (2007) 47: 237–249 DOI 10.1007/s11340-006-9013-9 Cure -dependent Viscoelastic Poisson’s Ratio of Epoxy D.J. O’Brien · N.R...Abstract The evolution of the lateral contraction ratio of two commercial (high and low temperature cure ) epoxy resins is studied in uniaxial tension

  16. Wear behaviour of epoxy resin filled with hard powders

    NASA Astrophysics Data System (ADS)

    Formisano, A.; Boccarusso, L.; Minutolo, F. Capece; Carrino, L.; Durante, M.; Langella, A.

    2016-10-01

    The development of high performance materials based on epoxy resin finds a growing number of applications in which high wear resistance is required. One major drawback in many of these applications is the relatively poor wear resistance of the epoxy resin. Therefore, in order to investigate on the possibility of increasing wear resistance of thermoset polymers filled with hard powders, sliding tests are carried out by means of a pin on disc apparatus. In particular, composite resins, constituted by an epoxy resin filled with different contents and sizes of Silicon Carbide powder, are analyzed; the wear resistance, in terms of volume loss, is measured for different abrasive counterfaces and loads.

  17. Epoxy bond and stop etch fabrication method

    DOEpatents

    Simmons, Jerry A.; Weckwerth, Mark V.; Baca, Wes E.

    2000-01-01

    A class of epoxy bond and stop etch (EBASE) microelectronic fabrication techniques is disclosed. The essence of such techniques is to grow circuit components on top of a stop etch layer grown on a first substrate. The first substrate and a host substrate are then bonded together so that the circuit components are attached to the host substrate by the bonding agent. The first substrate is then removed, e.g., by a chemical or physical etching process to which the stop etch layer is resistant. EBASE fabrication methods allow access to regions of a device structure which are usually blocked by the presence of a substrate, and are of particular utility in the fabrication of ultrafast electronic and optoelectronic devices and circuits.

  18. Measurement of damping of graphite epoxy materials

    NASA Technical Reports Server (NTRS)

    Crocker, M. J.

    1985-01-01

    The design of an experiment to measure the damping of a cylindrical graphite-epoxy specimen with a three point support and a knife edge support is described as well as equipment used in tests conducted to determine the influence of the support at the two ends of the specimen and to simulate an idealized free-free boundary condition at the two edges. A curve fitting technique is being used to process the frequency response data obtained. Experiments conducted on the thin plate specimen also reveal the influence of the end support condition on the damping ratio of the specimen. The damping ratio values measured for both specimens appear to be strongly influenced by the shape of the specimen and appear to depend on length and fiber orientation as well as the presence of discontinuities such as sharp bends, corners, and notches.

  19. Epoxy coatings over latex block fillers

    SciTech Connect

    Vincent, L.D.

    1997-12-01

    Failures of polymerized epoxy coatings applied over latex/acrylic block fillers continue to plague owners of commercial buildings, particularly those with high architectural content such as condominiums, high rise offices, etc. Water treatment facilities in paper mills are especially prone to this problem. The types of failures include delamination of the topcoats, blisters in both the block fillers and the topcoats and disintegration of the block filler itself. While the problem is well known, the approach to a solution is not. A study of several coatings manufacturer`s Product Data Sheets shows a wide variance in the recommendations for what are purportedly generically equivalent block fillers. While one manufacturer might take an essentially architectural approach, another will take a heavy-duty industrial approach. To the specifying architect or engineer who has little training in the complexities of protective coating systems, this presents a dilemma. Who does he believe? What does he specify? To whom can he turn for independent advice?

  20. Cellulose whisker/epoxy resin nanocomposites.

    PubMed

    Tang, Liming; Weder, Christoph

    2010-04-01

    New nanocomposites composed of cellulose nanofibers or "whiskers" and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of approximately 10 and approximately 84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight of 185-192 and a diethyl toluenediamine-based curing agent. Thin films were produced by casting these mixtures and subsequent curing. The whisker content was systematically varied between 4 and 24% v/v. Electron microscopy studies suggest that the whiskers are evenly dispersed within the epoxy matrix. Dynamic mechanical thermoanalysis revealed that the glass transition temperature (T(g)) of the materials was not significantly influenced by the incorporation of the cellulose filler. Between room temperature and 150 degrees C, i.e., below T(g), the tensile storage moduli (E') of the nanocomposites increased modestly, for example from 1.6 GPa for the neat polymer to 4.9 and 3.6 GPa for nanocomposites comprising 16% v/v tunicate or cotton whiskers. The relative reinforcement was more significant at 185 degrees C (i.e., above T(g)), where E' was increased from approximately 16 MPa (neat polymer) to approximately 1.6 GPa (tunicate) or approximately 215 MPa (cotton). The mechanical properties of the new materials are well-described by the percolation model and are the result of the formation of a percolating whisker network in which stress transfer is facilitated by strong interactions between the whiskers.

  1. Improvement of fracture toughness of epoxy resins at cryogenic temperature

    SciTech Connect

    Nishijima, S.; Yamada, K.; Hussain, M.; Honda, Y.

    1997-06-01

    The improvement of the fracture toughness of epoxy resin has been tried to perform from the molecular level with an aim to improve the cryogenic properties of GFRP and/or the stability of superconducting magnets. The ceramic filler, which was formed by hydrolysis of alkoxide, was dispersed in the epoxy and cured. A coupling agent was also used to crosslink the filler and epoxy molecules. The positron annihilation lifetime was measured and the molecular state of the epoxies were evaluated. The thermal contraction and Vickers hardness were also measured. The thermal contraction and hardness were confirmed to reflect the molecular state as evaluated by positron annihilation lifetime. The fracture toughness was also measured down to cryogenic temperatures. It was found that the improvement of the fracture toughness at cryogenic temperatures is possible.

  2. Magnetism in graphene oxide induced by epoxy groups

    SciTech Connect

    Lee, Dongwook; Seo, Jiwon; Zhu, Xi; Su, Haibin; Cole, Jacqueline M.

    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.

  3. Electrical and Mechanical Characteristics of Epoxy-Nanoclay Composite

    NASA Astrophysics Data System (ADS)

    Noh, Hyun-Ji; Nam, Sung-Pill; Lee, Sung-Gap; Ahn, Byeong-Lib; Won, Woo-Sik; Woo, Hyoung-Gwan; Park, Sang-Man

    In this study, we investigated the effects of nanoclay additives on the electrical and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) epoxy resin. Epoxy-clay nanocomposites were synthesized using organically modified two montmorillonite clays (MMT) with different interlamellar spacing (31.5 Å and 18.5 Å). The electrical and mechanical properties of epoxy-clay nanocopomosites were measured with variation of the amount and type of clay. The nanocomposites were found to be homogenous materials although the nanocomposites still have clay aggregates with increasing nanoclay contents. The dielectric constant showed between 3.2 ~ 3.5 and the dielectric loss showed between 3.2 ~ 5.7% in all nanocoposites. The dielectric strength and tensile strength of the 5 wt% Cloisite 15A added epoxy-oclay nanocomposite were 23.9 kV/mm and 86.7 MPa, respectively.

  4. Morphology development of layered silicate epoxy based nanocomposites

    NASA Astrophysics Data System (ADS)

    Benson Tolle, Tia

    2005-07-01

    Nanotailoring of polymeric materials offers significant benefits in terms of new and improved properties or new property trade spaces. Significant improvements to thermoplastics have been demonstrated over the past decade stimulated by the pioneering work of Kojima, Usuki, and Okada. The ability to nanotailor epoxy-based composites could have significant payoffs to aerospace and non-aerospace applications. However the dynamic nature of a crosslinking system such as epoxies poses unique challenges to the development of controlled morphologies. Before ultimate control of morphology and material design towards property enhancements can occur, fundamental understanding of how morphologies of various scales develop with processing parameters must be developed. This dissertation summarizes the effects of various processing variables on the development of morphology within organically modified layered silicate-epoxy-amine materials. The effect of various morphologies on fracture behavior is also examined, and suggests that ordered morphologies on the nanoscale can provide for effective toughening of epoxies.

  5. Method of making superhydrophobic/superoleophilic paints, epoxies, and composites

    DOEpatents

    Simpson, John T.; Hunter, Scott Robert

    2016-05-10

    Superhydrophobic paints and epoxies comprising superoleophilic particles and surfaces and methods of making the same are described. The superoleophilic particles can include porous particles having a hydrophobic coating layer deposited thereon. superoleophilic particles.

  6. Autonomic healing of carbon fiber/epoxy interfaces.

    PubMed

    Jones, Amanda R; Cintora, Alicia; White, Scott R; Sottos, Nancy R

    2014-05-14

    A maximum of 91% recovery of interfacial shear strength (IFSS) is achieved for carbon fiber/epoxy interfaces functionalized with capsules containing reactive epoxy resin and ethyl phenyl acetate (EPA). We find a binder is necessary to improve the retention of capsules on the carbon fiber surface. Two different methods for applying the binder to the carbon fiber surface are investigated. Healing efficiency is assessed by recovery of IFSS of a single functionalized fiber embedded in a microdroplet of epoxy. Debonding of the fiber/matrix interface ruptures the capsules, releasing resin and EPA solvent into the crack plane. The solvent swells the matrix, initiating transport of residual amine functionality from the matrix for further curing with the epoxy resin delivered to the crack plane. The two binder protocols produce comparable results, both yielding higher recovery of IFSS than samples prepared without a binder.

  7. Aging and quality assurance of Kevlar 49-epoxy composites

    SciTech Connect

    Morgan, R.J.

    1981-05-15

    The aging of Kevlar 49-epoxy composites under the service environment conditions expected by ESA will be insignificant to the best of our knowledge at this time. However, certain precautions in materials acceptance criteria and composite fabrication should be followed.

  8. Epoxy injection repairs to concrete in 225-B Building

    SciTech Connect

    Vollert, F.R.

    1996-09-19

    In 1982, the damaged anchor areas (67 total) in the Operating Gallery and cold manipulator shop ceiling reinforced concrete slabs were epoxy injection repaired by Construction Technology Laboratories (CTL), Portland Cement Association. The through depth vertical cracks (10 total) in the ceiling slabs in the galleries and manipulator shops were sealed and structurally repaired using epoxy injection procedures. The details of the epoxy reRair are reported. Sonic nondestructive (NDT) testing before and after the epoxy injection repairs were made by CTL to confirm that the repairs are structurally effective. CTL recommended to expedite the installation of lateral bracing for the manipulator monorail in order to avoid re-darnage to the repaired anchor areas.

  9. Exit Presentation: Infrared Thermography on Graphite/Epoxy

    NASA Technical Reports Server (NTRS)

    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

  10. Infrared Spectroscopy Study of the SP-250 Epoxy Resin System.

    DTIC Science & Technology

    1984-07-01

    It necessary and identify by block nambo,) Epoxy resins Dicyandiamide 4 Curing agents Infrared spectroscopy Monuron 20. ABSTRACT (Crntimse on revse...investigation, the mixtures containing Monuron were cured at 130 0 C and those con- sisting of dicyandiamide and having "no Monuron" were hardened at 2000...uncured specimens were meas- ured from 4000 cm- 1 to 400 cm- I . DISCUSSION AND RESULTS The accelerated cure of dicyandiamide (Dicy)-containing epoxy resins

  11. Medium temperature epoxy resin for immunocytochemistry: Quetol 651 with water.

    PubMed

    Abad, A R

    1992-02-01

    The addition of 1% water to the epoxy resin Quetol increased the labeling intensity of the sample. The significant decrease of the curing temperature of the epoxy resin may assist in preservation of antigens. Water may also reduce the cross-linkage of the resin allowing more antigen to be available to the antibodies. The modified Quetol resin is an option for use in immunocytochemistry studies.

  12. Fiber/epoxy filament-wound vessels. Final report

    SciTech Connect

    Chiao, T.T.; Moore, R.L.

    1986-08-14

    The present investigation has provided a valuable insight into the design, fabrication and performance of filament-wound pressure vessels. The long-term stress rupture data generated under the contract is perhaps the only available lifetime data of its kind for Kevlar 49/epoxy pressure vessels. Now, it is clear that Kevlar 49/epoxy pressure vessels can be made to last at least 9 years at 50% of the static burst pressure.

  13. Epoxy Nanocomposites - Curing Rheokinetics, Wetting and Adhesion to Fibers

    SciTech Connect

    Ilyin, S. O.; Kotomin, S. V.; Kulichikhin, V. G.

    2010-06-02

    Epoxy nanocomposites considered as challenging polymeric matrix for advanced reinforced plastics. Nanofillers change rheokinetics of epoxy resin curing, affect wetting and adhesion to aramid and carbon fibers. In all cases extreme dependence of adhesive strength vs filler content in the binder was observed. New experimental techniques were developed to study wettability and fiber-matrix adhesion interaction, using yarn penetration path length, aramid fiber knot pull-up test and electrical admittance of the fracture surface of CFRP.

  14. Epoxy Nanocomposites—Curing Rheokinetics, Wetting and Adhesion to Fibers

    NASA Astrophysics Data System (ADS)

    Ilyin, S. O.; Kotomin, S. V.; Kulichikhin, V. G.

    2010-06-01

    Epoxy nanocomposites considered as challenging polymeric matrix for advanced reinforced plastics. Nanofillers change rheokinetics of epoxy resin curing, affect wetting and adhesion to aramid and carbon fibers. In all cases extreme dependence of adhesive strength vs filler content in the binder was observed. New experimental techniques were developed to study wettability and fiber-matrix adhesion interaction, using yarn penetration path length, aramid fiber knot pull-up test and electrical admittance of the fracture surface of CFRP.

  15. Investigation of waterborne epoxies for E-glass composites

    NASA Astrophysics Data System (ADS)

    Jensen, Robert Eric

    Research is presented which encompasses a study of epoxies based on diglycidyl ether of bisphenol A (DGEBA) cured with 2-ethyl-4-methylimidazole (EMI-24) in the presence of the nonionic surfactant Triton X-100. Interest in this epoxy system is due partially to the potential application as a waterborne replacement for solvent cast epoxies in E-glass laminated printed circuit boards. This research has revealed that the viscoelastic behavior of the cured epoxy is altered when serving as the matrix in a glass composite. The additional constraining and coupling of the E-glass fibers to the segmental motion of the epoxy matrix results in an increased level of viscoelastic cooperativity. Current research has determined that the cooperativity of an epoxy/E-glass composite is also sensitive to the surface chemistry of the glass fibers. Model single-ply epoxy/E-glass laminates were constructed in which the glass was pretreated with either 3-aminopropyltriethoxysilane (APS) or 3-glycidoxypropyltrimethoxysilane (GPS) coupling agents. Dynamic mechanical analysis (DMA) was then used to create master curves of the storage modulus (E') in the frequency domain. The frequency range of the master curves and resulting cooperativity plots clearly varied depending on the surface treatment of the glass fibers. It was determined that the surfactant has surprisingly little effect in the observed trends in cooperativity of the composites. However, the changes in cooperativity due to the surface pretreatment of the glass were lessened by the aqueous phase of the waterborne resin. Moisture uptake experiments were also performed on epoxy samples that were filled with spherical glass beads as well as multi-ply laminated composites. No increases in the diffusion constant could be attributed to the surfactant. However, the surfactant did enhance the final equilibrium moisture uptake levels. These equilibrium moisture uptake levels were also sensitive to the surface pretreatment of the E-glass.

  16. Theoretical studies of radiation effects in composite materials for space use. [graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Chang, C. K.; Kamaratos, E.

    1982-01-01

    Tetraglycidyl 4,4'-diamino diphenyl methane epoxy cured with diamino diphenyl sulfone was used as a model compound. Computer programs were developed to calculate (1) energy deposition coefficients of protons and electrons of various energies at different depths of the material; (2) ranges of protons and electrons of various energies in the material; and (3) cumulative doses received by the composite in different geometric shapes placed in orbits of various altitudes and inclination. A preliminary study on accelerated testing was conducted and it was found that an elliptical equitorial orbit of 300 km perigee by 2750 km apogee can accumulate, in 2 years or less, enough radiation dose comparable to geosynchronous environment for 30 years. The local plasma model calculated the mean excitation energies for covalent and ionic compounds. Longitudinal and lateral distributions of excited species by electron and proton impact as well as the probability of overlapping of two tracks due to two charged particles within various time intervals were studied.

  17. Investigation of the effects of cobalt ions on epoxy properties

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Stoakley, D. M.

    1986-01-01

    The effects of Co(acac)sub x complexes on MY-720 epoxy properties have been investigated. It appears that Co2(+) ions form antibonding or nonbonding orbitals which increase the free volume and also reduce the cohesiveness of the host epoxy. The effects of Co2(+) ions, on the other hand, seem to result in increased Cohesiveness of the epoxy. The experimental values of magnetic moments of both types of ions in MY-720 suggest that the orbital momentum contributions of the (3d) electrons are partially conserved, though the effect is more pronounced for Co2(+) ions. The coordination environment of the cobalt ions in the host epoxy does not appear to be uniquely defined. These results indicate that the effects of metal ions on resin properties cannot be easily predicted on the basis of ligand field theory argument alone. Complex interactions between metal ions and host epoxy molecular structure suggest the desirability of parallel experimental investigations of electronic, magnetic, and mechanical properties of metal ion-containing epoxy samples for comparison with theory.

  18. Hygrothermal aging effects on buried molecular structures at epoxy interfaces.

    PubMed

    Myers, John N; Zhang, Chi; Lee, Kang-Wook; Williamson, Jaimal; Chen, Zhan

    2014-01-14

    Interfacial properties such as adhesion are determined by interfacial molecular structures. Adhesive interfaces in microelectronic packages that include organic polymers such as epoxy are susceptible to delamination during accelerated stress testing. Infrared-visible sum frequency generation vibrational spectroscopy (SFG) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used to study molecular structures at buried epoxy interfaces during hygrothermal aging to relate molecular structural changes at buried interfaces to decreases in macroscopic adhesion strength. SFG peaks associated with strongly hydrogen bonded water were detected at hydrophilic epoxy interfaces. Ordered interfacial water was also correlated to large decreases in interfacial adhesion strength that occurred as a result of hygrothermal aging, which suggests that water diffused to the interface and replaced original hydrogen bond networks. No water peaks were observed at hydrophobic epoxy interfaces, which was correlated with a much smaller decrease in adhesion strength from the same aging process. ATR-FTIR water signals observed in the epoxy bulk were mainly contributed by relatively weakly hydrogen bonded water molecules, which suggests that the bulk and interfacial water structure was different. Changes in interfacial methyl structures were observed regardless of the interfacial hydrophobicity which could be due to water acting as a plasticizer that restructured both the bulk and interfacial molecular structure. This research demonstrates that SFG studies of molecular structural changes at buried epoxy interfaces during hygrothermal aging can contribute to the understanding of moisture-induced failure mechanisms in electronic packages that contain organic adhesives.

  19. Thermo-curable epoxy systems for nanoimprint lithography

    NASA Astrophysics Data System (ADS)

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

    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.

  20. Effect of carbon nanotube addition on the wear behavior of basalt/epoxy woven composites.

    PubMed

    Kim, M T; Rhee, K Y; Lee, B H; Kim, C J

    2013-08-01

    The effect of acid-treated carbon nanotube (CNT) addition on the wear and dynamic mechanical thermal properties of basalt/epoxy woven composites was investigated in this study. Basalt/CNT/epoxy composites were fabricated by impregnating woven basalt fibers into epoxy resin mixed with 1 wt% CNTs which were acid-treated. Wear and DMA (dynamic mechanical analyzer) tests were performed on basalt/epoxy composites and basalt/CNT/epoxy composites. The results showed that the addition of the acid-treated CNTs improved the wear properties of basalt/epoxy woven composites. Specifically, the friction coefficient of the basalt/epoxy composite was stabilized in the range of 0.5-0.6 while it fell in the range of 0.3-0.4 for basalt/CNT/epoxy composites. The wear volume loss of the basalt/CNT/epoxy composites was approximately 68% lower than that of the basalt/epoxy composites. The results also showed that the glass transition temperature of basalt/CNT/epoxy composites was higher than that of basalt/epoxy composites. The improvement of wear properties of basalt/epoxy composites by the addition of acid-treated CNTs was caused by the homogeneous load transfer between basalt fibers and epoxy matrix due to the reinforcement of CNTs.

  1. Shock Equation of State of Multi-Phase Epoxy-Based Composite (Al-MnO2-Epoxy)

    DTIC Science & Technology

    2010-10-01

    There are several studies in the literature regarding the equation of state of alumina-epoxy composites. Although these single component systems...paper presents the shock equation of state results on a multi-phase composite Al-MnO2-epoxy. Equation of state experiments were conducted using three...The experimental equation of state data is compared to volume averaged and mesoscale mixture models.

  2. Bioactive compounds from Iostephane heterophylla (Asteraceae).

    PubMed

    Aguilar, M I; Delgado, G; Hernández, M L; Villarreal, M L

    2001-01-01

    The novel bisabolene sesquiterpenes 3-6, were isolated from Iostephane heterophylla, using bioguided fractionation. The new compounds were determined to be (12R/12S)-12,13-epoxy-xanthorrhizols (3,4) and (12R/12S)-12,13-dihydro-12,13-dihydroxy-xanthorrizols (5,6) and their structures were characterized by analysis of spectroscopic data and by chemical correlation from xanthorrhizol (2). The stereochemistry at C-12 of 5 was deduced using the modified Mosher experiment. Some of the isolated compounds elicited activity against gram positive and gram negative bacteria, levadura and dermatophytes.

  3. Viscoelastic properties of graphene-based epoxy resins

    NASA Astrophysics Data System (ADS)

    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.

  4. Composite Bombcase Program: Static tests on Kevlar/epoxy and graphite/epoxy plates and rings

    SciTech Connect

    Guess, T.R.

    1986-10-01

    An experimental study supporting the Composite Bombcase Program is described. The purpose of the study was to generate mechanical properties and structural response data on composite plates and cylinders. This data base is now available to assist in the evaluation of composite materials for bombcase applications. Two composites, Kevlar 49/epoxy and IM6 graphite/epoxy, were chosen for testing. The mechanical properties from flat unidirectional specimens were used to predict the elastic response of thick quasi-isotropic laminates in four-point bending and the elastic response of 18.0 inch diameter quasi-isotropic rings to diametral compressive loading. Good agreement between theoretical and experimental values of elastic response was obtained for both geometries. Load-deflection and load-strain curves in the elastic, post-yield, and failure regions were obtained for composite and aluminum rings. Delamination between plies was the principal failure mode in the QI composite plate and ring specimens. Even with many delaminations at large deflections, composite rings continued to carry load and retain some structural integrity.

  5. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    NASA Astrophysics Data System (ADS)

    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

  6. Curing and toughening of epoxy resins with phosphorus containing monomers and polymers

    SciTech Connect

    Park, Y.R.; Park, I.Y.; Yoon, T.H.

    1996-12-31

    Epoxy resins have been utilized in many areas, from house holds to airplanes, for the past several decades due to some exceptional properties such as low cost, good mechanical properties and excellent adhesive properties. However, low fracture toughness and flame resistance of epoxy resins have limited their applicability. Therefore, enhancing those properties have been of great interest to many researchers and scientists. As introduced by McGrath and co-workers in 1980s, the reactive thermoplastic polymers have proven to be an excellent toughener for improving not only fracture toughness but also adhesive properties without sacrificing thermo-mechanical properties and chemical resistance. Flame retardency could be improved by adding flame retardent additives which are divided into two groups; additives and reactives. However, among the additives, halogen compounds are known to be toxic gas generator and ozone depleter. Moreover, additives could be potentially leached out of the material, while reactives are inferior to additives. Recently, a reactive type phosphine oxide containing flame retardants have been introduced by McGrath and co-workers and proven to be an excellent flame retardant. In this paper, phospine oxide containing monomers were prepared and utilized as curing agents for expoxy resins, and starting materials for the polymers.

  7. Epoxy ceriporic acid produced by selective lignin-degrading fungus Ceriporiopsis subvermispora.

    PubMed

    Nishimura, Hiroshi; Setogawa, Yuichi; Watanabe, Takahito; Honda, Yoichi; Watanabe, Takashi

    2011-11-01

    Ceriporiopsis subvermispora is a selective white rot basidiomycete which degrades lignin in wood at a distance far from enzymes. Low molecular mass metabolites play a central role in the oxidative degradation of lignin. To understand the unique wood-decaying mechanism, we surveyed the oxidized derivatives of ceriporic acids (alk(en)ylitaconic acids) produced by C. subvermispora using high-resolution liquid chromatography multiple-stage mass spectrometry (HR-LC/MS(n)). The analysis of the precursor and product ions from the extract suggested that an epoxidized derivative of ceriporic acid is produced by the fungus. To identify the new metabolite, an authentic compound of ceriporic acid epoxide was synthesized in vitro by reacting (R)-3-[(Z)-hexadec-7-enyl]-itaconic acid (ceriporic acid C) with m-chloroperbenzoic acid. The precursor and product ions from the natural metabolite and authentic epoxide were identical and distinguishable from those of hydroxy and hydroperoxy derivatives after reduction with NaBD(4). Feeding experiments with [U-(13)C]-glucose, 99% and the subsequent analyses of the first and second generation product ions demonstrated that the oxidized ceriporic acid was (R)-3-(7,8-epoxy-hexadecyl)-itaconic acid. To our knowledge, this study is the first to report that natural alkylitaconic acid bears an epoxy group on its side chain.

  8. Catalytic diastereoselective reduction of α,β-epoxy and α,β-aziridinyl ynones.

    PubMed

    Druais, Valérie; Meyer, Christophe; Cossy, Janine

    2012-01-20

    The Noyori transfer hydrogenation of α,β-epoxy and α,β-aziridinyl ynones leads to the corresponding α,β-epoxy or α,β-aziridinyl propargylic alcohols with high reagent-controlled diastereoselectivity.

  9. ETV Program Report: Coatings for Wastewater Collection Systems - Standard Cement Materials, Epoxy Coating 4553

    EPA Science Inventory

    The Standard Cement Materials, Inc. Standard Epoxy Coating 4553™ (SEC 4553) epoxy coating used for wastewater collection system rehabilitation was evaluated by EPA’s Environmental Technology Verification Program under laboratory conditions at the Center for Innovative Grouting Ma...

  10. Statistical analysis of Kevlar 49/epoxy composite stress-rupture data

    SciTech Connect

    Glaser, R.E.

    1983-09-01

    Statistical analyses are presented for LLNL stress-rupture data sets involving kevlar 49/epoxy strands and NASA Kevlar 49/epoxy spherical pressure vessels subjected to sustained loading. Raw data, summarized inferences, and figures are included.

  11. High-performance fiber/epoxy composite pressure vessels

    NASA Technical Reports Server (NTRS)

    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.

  12. Electron beam curing of epoxy resins by cationic polymerization

    SciTech Connect

    Janke, C.J.; Dorsey, G.F.; Havens, S.J.; Lopata, V.J.

    1995-10-01

    Preliminary investigations have determined that conventional epoxy resins can be cured at selectable temperatures with high glass transition temperatures (essentially the same as with thermal curing), while still exhibiting equivalent or comparable mechanical properties. A cationic photoinitiator at a concentration of 1--3 parts per hundred of the epoxy resin is required for this process. Gamma cell screening of cationic photoinitiators with bisphenol A, bisphenol F, and cycloaliphatic epoxies demonstrated that diaryliodonium salts of weakly nucleophilic anions such as hexafluoroantimonate are most effective. Diaryliodonium salts were also found to be most effective initiators for the cationic polymerization of epoxy resins when a high energy/power electron beam accelerator was used as the source of ionizing radiation. For example Dow Tactix 123 (bisphenol A epoxy) containing 3 phr (4-octyloxyphenyl)phenyliodonium hexafluoroantimonate was irradiated at a total dosage of 100 kGy. Glass transition temperature (tan delta) of the cured material as determined by dynamic mechanical analysis was 182 C as compared to 165 C thermally cured material.

  13. Homogeneous Liquid Phase Transfer of Graphene Oxide into Epoxy Resins.

    PubMed

    Amirova, Lyaysan; Surnova, Albina; Balkaev, Dinar; Musin, Delus; Amirov, Rustem; Dimiev, Ayrat M

    2017-04-05

    The quality of polymer composite materials depends on the distribution of the filler in the polymer matrix. Due to the presence of the oxygen functional groups, graphene oxide (GO) has a strong affinity to epoxy resins, providing potential opportunity for the uniform distribution of GO sheets in the matrix. Another advantage of GO over its nonoxidized counterpart is its ability to exfoliate to single-atomic-layer sheets in water and in some organic solvents. However, these advantages of GO have not yet been fully realized due to the lack of the methods efficiently introducing GO into the epoxy resin. Here we develop a novel homogeneous liquid phase transfer method that affords uniform distribution, and fully exfoliated condition of GO in the polymer matrix. The most pronounced alteration of properties of the cured composites is registered at the 0.10%-0.15% GO content. Addition of as little as 0.10% GO leads to the increase of the Young's modulus by 48%. Moreover, we demonstrate successful introduction of GO into the epoxy matrix containing an active diluent-modifier; this opens new venues for fabrication of improved GO-epoxy-modifier composites with a broad range of predesigned properties. The experiments done on reproducing the two literature methods, using alternative GO introduction techniques, lead to either decrease or insignificant increase of the Young's modulus of the resulting GO-epoxy composites.

  14. Void-free epoxy castings for cryogenic insulators and seals

    SciTech Connect

    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.

  15. Epoxy resin/carbon black composites below the percolation threshold.

    PubMed

    Macutkevic, J; Kuzhir, P; Paddubskaya, A; Maksimenko, S; Banys, J; Celzard, A; Fierro, V; Stefanutti, E; Cataldo, A; Micciulla, F; Bellucci, S

    2013-08-01

    A set of epoxy resin composites filled with 0.25-2.0 wt.% of commercially available ENSACO carbon black (CB) of high and low surface area (CBH and CBL respectively) has been produced. The results of broadband dielectric spectroscopy of manufactured CB/epoxy below the percolation threshold in broad temperature (200 K to 450 K) and frequency (20 Hz to 1 MHz) ranges are reported. The dielectric properties of composites below the percolation threshold are mostly determined by alpha relaxation in pure polymer matrix. The glass transition temperature for CB/epoxy decreases in comparison with neat epoxy resin due to the extra free volume at the polymer-filler interface. At room temperature, the dielectric permittivity is higher for epoxy loaded with CBH additives. In contrast, at high temperature, the electrical conductivity was found to be higher for composites with CBL embedded. The established influence of the CB surface area on the broadband dielectric characteristics can be exploited for the production of effective low-cost antistatic paints and coatings working at different temperatures.

  16. Fiber-Reinforced Reactive Nano-Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Zhong, Wei-Hong

    2011-01-01

    An ultra-high-molecular-weight polyethylene/ matrix interface based on the fabrication of a reactive nano-epoxy matrix with lower surface energy has been improved. Enhanced mechanical properties versus pure epoxy on a three-point bend test include: strength (25 percent), modulus (20 percent), and toughness (30 percent). Increased thermal properties include higher Tg (glass transition temperature) and stable CTE (coefficient of thermal expansion). Improved processability for manufacturing composites includes faster wetting rates on macro-fiber surfaces, lower viscosity, better resin infusion rates, and improved rheological properties. Improved interfacial adhesion properties with Spectra fibers by pullout tests include initial debonding force of 35 percent, a maximum pullout force of 25 percent, and energy to debond at 65 percent. Improved mechanical properties of Spectra fiber composites (tensile) aging resistance properties include hygrothermal effects. With this innovation, high-performance composites have been created, including carbon fibers/nano-epoxy, glass fibers/nano-epoxy, aramid fibers/ nano-epoxy, and ultra-high-molecularweight polyethylene fiber (UHMWPE).

  17. Dynamic Mechanical Behavior of Nickel-Aluminum Reinforced Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Martin, Morgana; Hanagud, Sathyanaraya; Thadhani, Naresh

    2005-07-01

    Epoxy-based composites reinforced with a mixture of micron-sized Ni and micron or nano-sized Al powders were fabricated as bulk materials by cast/curing. The structural/mechanical behavior of these materials was evaluated using elastic and plastic property measurements via static and dynamic compression tests performed on rod shaped samples. Reverse Taylor anvil-on-rod impact tests combined with velocity interferometry gave qualitative and quantitative information about the transient deformation and failure response of the composites. The material containing 20wt% epoxy and nano-sized Al powder showed the most superior mechanical properties in terms of elastic modulus, and static and dynamic compressive strength, and strain before fracture, as compared to the other reinforced cast materials. The results illustrate that nano-sized Al particles provide significant enhancement to strength of epoxy composites by dispersing in the epoxy and generating a nano-Al containing epoxy matrix with embedded Ni particles. Funding for this research was provided by AFOSR/MURI Grant No. F49620-02-1-0382.

  18. Viscoelasticity of Epoxy nano-composites

    NASA Astrophysics Data System (ADS)

    Ahuja, Suresh

    2013-03-01

    Nanocomposites have been modeled in a multiscale covering from molecular scale (e.g., molecular dynamics, Monte Carlo), microscale (e.g., Brownian dynamics, dissipative particle dynamics, lattice Boltzmann, time-dependent Ginzburg-Landau method, dynamic density functional theory method) to mesoscale and macroscale (e.g., micromechanics, equivalent-continuum and self-similar approaches, finite element method) The presence of layered silicates in nonaqueous polymers changes the viscoelastic behavior of the unfilled matrix from liquid-like to solid-like because of the formation of a three-dimensional percolating network of exfoliated or intercalated stacks. This gel-like behavior is a direct consequence of the highly anisotropic nature of the nanoclays which prevents their free rotation and the dissipation of stress. Particle to particle interactions is the dominant mechanism in fumed silica nanocomposites whereas particle to polymer interaction is the dominant one in colloidal silica nanocomposites at identical filler concentrations. These interactions are balanced in each nanocomposite systems by the silica surface treatments (chain grafting, silane modification) and the molecular weight of the matrix. Two different types of nanocomposite structures exist namely, intercalated nanocomposites where the polymer chains are sandwiched between silicate layers and exfoliated nanocomposites where the layers can be considered individually but remain more or less dispersed in the polymer matrix. Yield stress from Carreau-Yasuda model has been correlated to exfoliation. Also, equilibrium modulus and zero shear rate viscosity has been used to analyze percolation threshold and sol-gel transition. Nano clays organically functionalized were mixed with Epoxy in a high shear mixer.

  19. Curing of epoxy matrix composite in stratosphere

    NASA Astrophysics Data System (ADS)

    Kondyurin, Alexey; Kondyurina, Irina; Bilek, Marcela

    Large structures for habitats, greenhouses, space bases, space factories are needed for next stage of space exploitation. A new approach enabling large-size constructions in space relies on the use of the polymerization technology of fiber-filled composites with a curable polymer matrix applied in the free space environment. The polymerisation process is proposed for the material exposed to high vacuum, dramatic temperature changes, space plasma, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The stratospheric flight experiments are directed to an investigation of the curing polymer matrix under the stratospheric conditions on. The unique combination of low atmospheric pressure, high intensity UV radiation including short wavelength UV and diurnal temperature variations associated with solar irradiation strongly influences the chemical processes in polymeric materials. The first flight experiment with uncured composites was a part of the NASA scientific balloon flight program realised at the NASA stratospheric balloon station in Alice Springs, Australia. A flight cassette installed on payload was lifted with a “zero-pressure” stratospheric balloon filled with Helium. Columbia Scientific Balloon Facility (CSBF) provided the launch, flight telemetry and landing of the balloon and payload. A cassette of uncured composite materials with an epoxy resin matrix was exposed 3 days in the stratosphere (40 km altitude). The second flight experiment was realised in South Australia in 2012, when the cassette was exposed in 27 km altitude. An analysis of the chemical structure of the composites showed, that the space irradiations are responsible for crosslinking of the uncured polymers exposed in the stratosphere. The first prepreg in the world was cured successfully in stratosphere. The investigations were supported by Alexander von Humboldt Foundation, NASA and RFBR (12-08-00970) grants.

  20. Interfacial Strength and Physical Properties of Functionalized Graphene - Epoxy Nanocomposites

    NASA Technical Reports Server (NTRS)

    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.

  1. Low-temperature mechanical properties of glass/epoxy laminates

    NASA Astrophysics Data System (ADS)

    Reed, R. P.; Madhukar, M.; Thaicharoenporn, B.; Martovetsky, N. N.

    2014-01-01

    Selected mechanical properties of glass/epoxy laminate candidates for use in the electrical turn and ground insulation of the ITER Central solenoid (CS) modules were measured. Short-beam shear and flexural tests have been conducted on various E-glass cloth weaves/epoxy laminates at 295 and 77 K. Types of glass weave include 1581, 7500, 7781, and 38050, which represent both satin and plain weaves. The epoxy, planned for use for vacuum-pressure impregnation of the CS module, consists of an anhydride-cured bisphenol F resin system. Inter-laminar shear strength, flexural elastic modulus, and flexural strength have been measured. The data indicate that these properties are dependent on the volume percent of glass. Short-beam shear strength was measured as a function of the span-to-thickness ratio for all laminates at 77 K. Comprehensive fractography was conducted to obtain the failure mode of each short-beam shear test sample.

  2. Epoxy foams using multiple resins and curing agents

    DOEpatents

    Russick, Edward M.; Rand, Peter B.

    2000-01-01

    An epoxy foam comprising a plurality of resins, a plurality of curing agents, at least one blowing agent, at least one surfactant and optionally at least one filler and the process for making. Preferred is an epoxy foam comprising two resins of different reactivities, two curing agents, a blowing agent, a surfactant, and a filler. According to the present invention, an epoxy foam is prepared with tailorable reactivity, exotherm, and pore size by a process of admixing a plurality of resins with a plurality of curing agents, a surfactant and blowing agent, whereby a foamable mixture is formed and heating said foamable mixture at a temperature greater than the boiling temperature of the blowing agent whereby said mixture is foamed and cured.

  3. Low-temperature mechanical properties of glass/epoxy laminates

    SciTech Connect

    Reed, R. P.; Madhukar, M.; Thaicharoenporn, B.; Martovetsky, N. N.

    2014-01-27

    Selected mechanical properties of glass/epoxy laminate candidates for use in the electrical turn and ground insulation of the ITER Central solenoid (CS) modules were measured. Short-beam shear and flexural tests have been conducted on various E-glass cloth weaves/epoxy laminates at 295 and 77 K. Types of glass weave include 1581, 7500, 7781, and 38050, which represent both satin and plain weaves. The epoxy, planned for use for vacuum-pressure impregnation of the CS module, consists of an anhydride-cured bisphenol F resin system. Inter-laminar shear strength, flexural elastic modulus, and flexural strength have been measured. The data indicate that these properties are dependent on the volume percent of glass. Short-beam shear strength was measured as a function of the span-to-thickness ratio for all laminates at 77 K. Comprehensive fractography was conducted to obtain the failure mode of each short-beam shear test sample.

  4. On sample preparation and dielectric breakdown in nanostructured epoxy resins

    NASA Astrophysics Data System (ADS)

    Reading, M.; Xu, Z.; Vaughan, A. S.; Lewin, P. L.

    2011-08-01

    There are many methods available to achieve a good dispersion of fillers within a polymeric matrix. This investigation considered several methods of dispersing three chosen fillers within an epoxy resin; the same processes were also performed on unfilled materials to investigate any effects they may have on the host material. For this investigation, the epoxy system (EP) was combined with sodium montmorillonite (MMT), micrometric silicon dioxide (SD) or nanometric silicon dioxide (NSD) as fillers. The effect of the different sample preparation routes on breakdown behaviour was then evaluated. While more thorough mixing protocols were found to lead to improved breakdown behaviour in the case of the various filled systems, surprisingly, an entirely equivalent form of behaviour was also seen in the unfilled epoxy. The influence of changes in sample geometry on the breakdown strength was established.

  5. Dielectric properties of inorganic fillers filled epoxy thin film

    NASA Astrophysics Data System (ADS)

    Norshamira, A.; Mariatti, M.

    2015-07-01

    The demand on the small size and high performance electronics has driven changes in the electronic packaging requirements from discrete capacitor to embedded capacitor. Embedded capacitor can improve electrical performance compared with discrete capacitor. This study aimed to achieve high dielectric of epoxy thin film composite that were targeted for application as embedded capacitor. In this study, inorganic fillers such as Calcium Copper Titanate (CCTO), Iron(III) Oxide (Fe2O3) and Titanium Dioxide (TiO2) were loaded in epoxy system at 5 and 20vol%. Morphology and dielectric properties were investigated to identify the effect of fillers loading and types of fillers on the properties of epoxy thin film composite. Based on the study, CCTO with 20vol% loading was found to have good dielectric properties compared to other type of fillers.

  6. Navigation of the EPOXI Spacecraft to Comet Hartley 2

    NASA Technical Reports Server (NTRS)

    Bhaskaran, Shyam; Abrahamson, Matt; Chesley, Steven; Chung, Min-Kun; Halsell, Allen; Haw, Robert; Helfrich, Cliff; Jefferson, David; Kennedy, Brian; McElrath, Tim; Owen, William; Rush, Brian; Smith, Jonathon; Wang, Tseng-Chan; Yen, Chen-Wan

    2011-01-01

    On November 4, 2010, the EPOXI spacecraft flew by the comet Hartley 2, marking the fourth time that a NASA spacecraft successfully captured high resolution images of a cometary nucleus. EPOXI is the extended mission of the Deep Impact mission, which delivered an impactor on comet Tempel-1 on July 4, 2005. EPOXI officially started in September 2007 and eventually took over 3 years of flight time and had 3 Earth gravity assists to achieve the proper encounter conditions. In the process, the mission was redesigned to accommodate a new comet as the target and changes in the trajectory to achieve better imaging conditions at encounter. Challenges in navigation of the spacecraft included precision targeting of several Earth flybys and the comet encounter, uncertainties in determining the ephemeris of the comet relative to the spacecraft, and the high accuracy trajectory knowledge needed to image the comet during the encounter. This paper presents an overview of the navigation process used for the mission.

  7. DEGRADATION OF MAGNET EPOXY AT NSLS X-RAY RING.

    SciTech Connect

    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.

  8. Dielectric properties of inorganic fillers filled epoxy thin film

    SciTech Connect

    Norshamira, A. Mariatti, M.

    2015-07-22

    The demand on the small size and high performance electronics has driven changes in the electronic packaging requirements from discrete capacitor to embedded capacitor. Embedded capacitor can improve electrical performance compared with discrete capacitor. This study aimed to achieve high dielectric of epoxy thin film composite that were targeted for application as embedded capacitor. In this study, inorganic fillers such as Calcium Copper Titanate (CCTO), Iron(III) Oxide (Fe{sub 2}O{sub 3}) and Titanium Dioxide (TiO{sub 2}) were loaded in epoxy system at 5 and 20vol%. Morphology and dielectric properties were investigated to identify the effect of fillers loading and types of fillers on the properties of epoxy thin film composite. Based on the study, CCTO with 20vol% loading was found to have good dielectric properties compared to other type of fillers.

  9. Health Problems of Epoxy Resins and Amine-curing Agents

    PubMed Central

    Bourne, L. B.; Milner, F. J. M.; Alberman, K. B.

    1959-01-01

    Epoxy resins were first introduced about 10 years ago. Toxic effects, particularly dermatitis, have been frequently described. An investigation into the possible causes of pathological sequelae following the use of epoxy resin/amine mixtures has been undertaken. The cause of most cases of dermatitis and sensitization appears to be uncombined amine which is present in recent mixtures and persists in hardened resin for long periods. The results of experiments with two of the most commonly used resin/amine mixtures confirm this. Cold-cured resins are more dangerous and remain so even when hardened. A simple theory is suggested for the mechanism of the reaction between epoxy resins, amines, and biological systems. This theory leads logically to the handling precautions outlined. Images PMID:13651551

  10. Research on fracture performance of epoxy asphalt concrete based on double-K fracture criterion

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Qian, Z. D.; Xue, Y. C.

    2017-01-01

    After cracks appear on steel bridge deck epoxy asphalt concrete pavement, cracks propagate fast under vehicle load. This paper studied the fracture performance of epoxy asphalt concrete, utilized single edge notched beam (SEB) three-point bending test, measured the load (P) exerted on epoxy asphalt SEB; utilized digital camera to record the fracture process of epoxy asphalt SEB, extracted the images according to the required sampling frequency and utilized Image-Pro Plus to measure the crack mouth opening displacement (CMOD) of epoxy asphalt SEB on the extracted images; calculated the double-K fracture parameters according to the P-CMOD curve. Results indicate that of epoxy asphalt concrete is 1.11 MPa and of epoxy asphalt concrete is 2.31 MPa at -15°C of epoxy asphalt concrete is 1.02 MPa and of epoxy asphalt concrete is 1.83 MPa at -5°C of epoxy asphalt concrete is 0.77 MPa and of epoxy asphalt concrete is 1.82 MPa at 5°C. The double-K fracture parameters of epoxy asphalt concrete increase slightly when the temperature decreases at the scope of -15°C to 5°C. The relation of and is .

  11. 40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... epoxy adduct. 721.1850 Section 721.1850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical... as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to reporting under...

  12. 40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... epoxy adduct. 721.1850 Section 721.1850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical... as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to reporting under...

  13. 40 CFR 721.10603 - Epoxy modified alkyd resin, partially neutralized (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Epoxy modified alkyd resin, partially... Specific Chemical Substances § 721.10603 Epoxy modified alkyd resin, partially neutralized (generic). (a... generically as epoxy modified alkyd resin, partially neutralized (PMN P-11-280) is subject to reporting...

  14. 40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... epoxy adduct. 721.1850 Section 721.1850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical... as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to reporting under...

  15. 40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... epoxy adduct. 721.1850 Section 721.1850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical... as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to reporting under...

  16. 40 CFR 721.10603 - Epoxy modified alkyd resin, partially neutralized (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Epoxy modified alkyd resin, partially... Specific Chemical Substances § 721.10603 Epoxy modified alkyd resin, partially neutralized (generic). (a... generically as epoxy modified alkyd resin, partially neutralized (PMN P-11-280) is subject to reporting...

  17. 40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... epoxy adduct. 721.1850 Section 721.1850 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical... as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to reporting under...

  18. 40 CFR 721.9270 - Reaction product of epoxy with anhydride and glycerol and glycol.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reaction product of epoxy with... Significant New Uses for Specific Chemical Substances § 721.9270 Reaction product of epoxy with anhydride and... substance identified generically as reaction product of epoxy with anhydride and glycerol and glycol (PMN...

  19. 40 CFR 721.9270 - Reaction product of epoxy with anhydride and glycerol and glycol.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reaction product of epoxy with... Significant New Uses for Specific Chemical Substances § 721.9270 Reaction product of epoxy with anhydride and... substance identified generically as reaction product of epoxy with anhydride and glycerol and glycol (PMN...

  20. 40 CFR 721.9270 - Reaction product of epoxy with anhydride and glycerol and glycol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of epoxy with... Significant New Uses for Specific Chemical Substances § 721.9270 Reaction product of epoxy with anhydride and... substance identified generically as reaction product of epoxy with anhydride and glycerol and glycol (PMN...

  1. 40 CFR 721.9270 - Reaction product of epoxy with anhydride and glycerol and glycol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of epoxy with... Significant New Uses for Specific Chemical Substances § 721.9270 Reaction product of epoxy with anhydride and... substance identified generically as reaction product of epoxy with anhydride and glycerol and glycol (PMN...

  2. 40 CFR 721.9270 - Reaction product of epoxy with anhydride and glycerol and glycol.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reaction product of epoxy with... Significant New Uses for Specific Chemical Substances § 721.9270 Reaction product of epoxy with anhydride and... substance identified generically as reaction product of epoxy with anhydride and glycerol and glycol (PMN...

  3. Understanding the strength of epoxy/polyimide interfaces

    NASA Astrophysics Data System (ADS)

    Hoontrakul, Patraporn

    Polyimides are commonly used as organic passivation layers for microelectronic devices due to their unique combination of low dielectric constant, high thermal stability, and excellent mechanical properties. Polyimides are well known to have poor adhesion to epoxy resins. Many surface treatment methods have been developed to increase epoxy-polyimide adhesion. These include various ion beam and plasma treatments as well as wet chemical methods. Our research goal is to understand the strength of epoxy-polyimide interfaces by studying the effect of polyimide chemical structure on epoxy-polyimide adhesion. Four polyimides that were chosen in this study were commonly used in microelectronic industries: poly (pyromellitic dianhydride-oxydianiline [PMDA-ODA], poly (3,3',4,4'-biphenyltetracarboxylic dianhydride-phenylene diamine [BPDA-PDA], poly (hexafluoroisopropylidene-diphthalic anhydride-oxydianiline) [6FDA-ODA], and 5(6)-Amino-1-(4-aminophenyl)-1,3,3, trimethylindanbenzophenonetetacarboxylic dianhydride copolymer [BTDA-DAPI). The adhesive strengths between an epoxy resin and these various polyimides were characterized using interfacial fracture mechanics and the critical interfacial strain energy release rates were found to be in the range of 20 J/m 2 to 179 J/m2. The locus of failure for fractured epoxy-polyimide interfaces were analyzed using scanning electron microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FT-IR) and found to be at the interphase region for all four interfaces. The surface reactivity was analyzed using flow microcalorimetry (FMC), FT-IR, and the contact angles. Interestingly, the strength of the interfaces appeared to be related to the predicted interfacial widths from solubility parameter theory.

  4. Toughening mechanism in elastomer-modified epoxy resins, part 2

    NASA Technical Reports Server (NTRS)

    Yee, A. F.; Pearson, R. A.

    1984-01-01

    The role of matrix ductility on the toughenability and toughening mechanism of elastomer-modified DGEBRA epoxies was investigated. Matrix ductility was varied by using epoxide resins of varying epoxide monomer molecular weights. These epoxide resins were cured using 4,4' diaminodiphenyl sulfone (DDS) and, in some cases, modified with 10% HYCAR(r)CTBN 1300X8. Fracture roughness values for the neat epoxies were found to be almost independent on the monomer molecular weight of the epoxide resin used. However, it was found that the fracture toughness of the elastomer-modified epoxies was very dependent upon the epoxide monomer molecular weight. Tensile dilatometry indicated that the toughening mechanism, when present, is similar to the mechanisms found for the piperidine cured epoxies in Part 1. SEM and OM corroborate this finding. Dynamic mechanical studies were conducted to shed light on the toughenability of the epoxies. The time-dependent small strain behavior of these epoxies were separated into their bulk and shear components. The bulk component is related to brittle fracture, whereas the shear component is related to yielding. It can be shown that the rates of shear and bulk strain energy buildup for a given stress are uniquely determined by the values of Poisson's ratio, nu. It was found that nu increases as the monomer molecular weight of the epoxide resin used increases. This increase in nu can be associated with the low temperature beta relaxation. The effect of increasing cross-link density is to shift the beta relaxation to higher temperatures and to decrease the magnitude of the beta relaxation. Thus, increasing cross-link density decreases nu and increases the tendency towards brittle fracture.

  5. Thermoset Blends of an Epoxy Resin and Polydicyclopentadiene

    SciTech Connect

    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.

  6. Education and Public Outreach for NASA's EPOXI Mission.

    NASA Astrophysics Data System (ADS)

    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

  7. Glass Fibre/Epoxy Resin Interface Life-Time Prediction.

    DTIC Science & Technology

    1983-04-01

    RD-Ai32 26 GLASS FIBRE /POXY RESIN INTERFACE LIFE-TIME PREDICTION 1/1 (U) BRISTOL UNIV (ENGLAND) H H WILLS PHYSICS LAB K H RSHBEE ET AL. APR 83...D 3005-MS GLASS FIBRE /EPOXY RESIN INTERFACE LIFE-TIME PREDICTION - Final Report by K H G Ashbee, Principal Investigator R Ho~l J P Sargent Elizabeth...REPORT h PERIOD COVERED. Glass Fibre /Epoxy Resin Interface Life-time F-inal Technical 11’ port PreictonApril 1981 - A:’ril 1983 6. PERFORMING ORG. REPORT

  8. Impact penetration studies of graphite/epoxy laminates

    NASA Technical Reports Server (NTRS)

    Sykes, G. F.; Stoakley, D. M.

    1980-01-01

    A study was conducted to provide an initial insight into the role of the matrix in impact energy absorption of graphite/epoxy laminates. A single epoxy system, NARMCO 5208, in both composite and cured neat-resin form was studied with a constant velocity impact test apparatus. The parameters investigated include resin cure temperature, fiber type, ply thickness and orientation, and impact velocity. The results from the study show that matrix chemistry, as obtained by cure temperature changes, has a significant effect upon the failure mode and energy absorption during impact.

  9. Mechanism of Monuron-Accelerated Dicyandiamide Cure of Epoxy Resins

    DTIC Science & Technology

    1981-07-01

    ÜBBSBBffl^w^r’r^^—. ■ «Mmfifißmwww-tr- oo o m* AMMRC TR 81-34 AD MECHANISM OF < MONURON-ACCELERATED ^ DICYANDIAMIDE CURE OF...REPORT NJJMMR RC-TR-81-34 2. GOVT ACCESSION NO. 4. TITLE fand Submit) AV-A/^if^ , MECHANISM OF MONURON-ACCELERATED DICYANDIAMIDE CURE OF EPOXY...4-chJqTophenyl)-tI,,N,-dimethylurea, >is the ability of this class of aryl ureas to accelerate the dicyandiamide (Dicy) cure of epoxy resins

  10. The radiation resistance of thermoset plastics—V. Epoxy plastics

    NASA Astrophysics Data System (ADS)

    Gilfrich, H.-P.; Wilski, H.

    Flexural strength, impact strength and dielectric properties of an epoxy plastic (bispherol A-based epoxy resin cured with aromatic diamines) with inorganic fillers remained unchanged after irradiation at high dose rate up to 10 MGy. Measurements of heat deflection temperature and sol fraction indicated, however, a deterioration of the resin. The same results were obtained after irradiation in the presence of air at extremely low dose rate (irradiation time: 10 years). Electrical surface resistance and tracking resistance worsened after irradiation. In addition, both of these surface-dependent properties were markedly influenced by the dose rate.

  11. Rheological and morphological properties of graphene-epoxy nanocomposites

    NASA Astrophysics Data System (ADS)

    Nobile, Maria Rossella; Raimondo, Marialuigia; Lafdi, Khalid; Guadagno, Liberata

    2016-05-01

    In this paper the rheological and morphological properties of an epoxy resin filled with graphene-based nanoparticles have been investigated. Two samples of partially exfoliated graphite (pEG) and carboxylated partially exfoliated graphite (CpEG), differing essentially for the content of carboxylated groups, are used. The percentage of exfoliated graphite is slightly different for the two samples: 56% for pEG and and 60% for CpEG. Exfoliated graphite is prepared using traditional acid intercalation followed by a sudden treatment at high temperature (900°C). The epoxy matrix is 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), is added at a stoichiometric concentration with respect to all the epoxy rings. The inclusion of the pEG and CpEG samples in the formulated epoxy mixture significantly modifies the rheological behaviour of the mixture itself. The epoxy mixture, indeed, shows a Newtonian behavior; on the contrary the complex viscosity of the nanocomposites clearly shows a shear thinning behavior at 3 wt % of pEG content and at 0.75 wt% of CpEG content. The increase in complex viscosity with the increasing of pEG and CpEG content is mostly caused by a dramatic increase in the storage modulus of the nanocomposites. All the graphene-based epoxy mixtures are cured by a two-stage curing cycles: a first isothermal stage is carried out at the lower temperature of 125°C for 1 hour and, then, a second isothermal stage at the higher temperature of 200°C for 3 hours. The different morphology shown by the two pEG and CpEG samples is consistent with the difference in the percentage of exfoliation degree and well correlates with the rheological behavior of investigated graphene-epoxy nanocomposites.

  12. Development of quality assurance methods for epoxy graphite prepreg

    NASA Technical Reports Server (NTRS)

    Chen, J. S.; Hunter, A. B.

    1982-01-01

    Quality assurance methods for graphite epoxy/prepregs were developed. Liquid chromatography, differential scanning calorimetry, and gel permeation chromatography were investigated. These methods were applied to a second prepreg system. The resin matrix formulation was correlated with mechanical properties. Dynamic mechanical analysis and fracture toughness methods were investigated. The chromatography and calorimetry techniques were all successfully developed as quality assurance methods for graphite epoxy prepregs. The liquid chromatography method was the most sensitive to changes in resin formulation. The were also successfully applied to the second prepreg system.

  13. Fracture behavior of silica nanoparticle filled epoxy resin

    NASA Astrophysics Data System (ADS)

    Dittanet, Peerapan

    This dissertation involves the addition of silica nanoparticles to a lightly crosslinked, model epoxy resin and investigates the effect of nanosilica content and particle size on glass transition temperature (Tg), coefficient of thermal expansion (CTE), Young's modulus (E), yield stress, and fracture toughness. This study aims to understand the influence of silica nanoparticle size, bimodal particle size distribution and silica content on the toughening behavior. The toughening mechanisms were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and transmission optical microscopy (TOM). The approach identifies toughening mechanisms and develops a toughening model from unimodal-particle size systems first, then extends these concepts to various mixtures micron- and nanometer-size particles in a similar model epoxy. The experimental results revealed that the addition of nanosilica did not have a significant effect on Tg or the yield stress of epoxy resin, i.e. the yield stress and Tg remained constant regardless of nanosilica particle size. As expected, the addition of nanosilica had a significant impact on CTE, modulus and fracture toughness. The CTE values of nanosilica-filled epoxies were found to decrease with increasing nanosilica content, which can be attributed to the much lower CTE of the nanosilica fillers. Interestingly, the decreases in CTE showed strong particle size dependence. The Young's modulus was also found to significantly improve with addition of nanosilica and increase with increasing filler content. However, the particle size did not exhibit any effect on the Young's modulus. Finally, the fracture toughness and fracture energy showed significant improvements with the addition of nanosilica, and increased with increasing filler content. The effect of particle size on fracture toughness was negligible. Observation of the fracture surfaces using SEM and TOM showed evidence of debonding of nanosilica particles

  14. Monomers for thermosetting and toughening epoxy resins. [glycidyl amine derivatives, propargyl-containing amines, and mutagenic testing of aromatic diamines

    NASA Technical Reports Server (NTRS)

    Pratt, J. R.

    1981-01-01

    Eight glycidyl amines were prepared by alkylating the parent amine with epichlorohydrin to form chlorohydrin, followed by cyclization with aqueous NaOH. Three of these compounds contained propargyl groups with postcuring studies. A procedure for quantitatively estimating the epoxy content of these glycidyl amines was employed for purity determination. Two diamond carbonates and several model propargly compounds were prepared. The synthesis of three new diamines, two which contain propargyloxy groups, and another with a sec-butyl group is in progress. These materials are at the dinitro stage ready for the final hydrogenation step. Four aromatic diamines were synthesized for mutagenic testing purposes. One of these compounds rapidly decomposes on exposure to air.

  15. Aerobic granular sludge inoculated microbial fuel cells for enhanced epoxy reactive diluent wastewater treatment.

    PubMed

    Cheng, Kai; Hu, Jingping; Hou, Huijie; Liu, Bingchuan; Chen, Qin; Pan, Keliang; Pu, Wenhong; Yang, Jiakuan; Wu, Xu; Yang, Changzhu

    2017-04-01

    Microbial consortiums aggregated on the anode surface of microbial fuel cells (MFCs) are critical factors for electricity generation as well as biodegradation efficiencies of organic compounds. Here in this study, aerobic granular sludge (AGS) was assembled on the surface of the MFC anode to form an AGS-MFC system with superior performance on epoxy reactive diluent (ERD) wastewater treatment. AGS-MFCs successfully shortened the startup time from 13d to 7d compared to the ones inoculated with domestic wastewater. Enhanced toxicity tolerance as well as higher COD removal (77.8% vs. 63.6%) were achieved. The higher ERD wastewater treatment efficiency of AGS-MFC is possibly attributed to the diverse microbial population on MFC biofilm, as well as the synergic degradation of contaminants by both the MFC anode biofilm and AGS granules.

  16. Stimuli-responsive cellulose modified by epoxy-functionalized polymer nanoparticles with photochromic and solvatochromic properties.

    PubMed

    Abdollahi, Amin; Rad, Jaber Keyvan; Mahdavian, Ali Reza

    2016-10-05

    Photoresponsive papers are among the fast and simple tools for detection of polarity by solvatochromic and photochromic behaviors upon UV irradiation. Here, a new, green and facile modification strategy was employed to prepare novel stimuli-responsive cellulose materials containing spiropyran by mixing microcrystalline cellulose (MCC), as a model compound, with epoxy-functionalized photochromic latex. FTIR analysis, thermal and thermo-mechanical properties were used to confirm the microstructral properties. Crystallographic analysis revealed a decrease in crystallinity of cellulose matrix and approved the incorporation of photochromic copolymer. Then stimuli-responsive papers were prepared by using pulp paper as the cellulosic matrix and their smart characteristics were studied under UV irradiation while dried or immersed into some polar and non-polar solvents. Different color changes were observed and investigated by solid-state UV-vis spectroscopy. These significant results were attributed to the efficient chemical modification and confirmed by SEM, EDX and nitrogen mapping analyses.

  17. Analytical and experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in compression

    NASA Technical Reports Server (NTRS)

    Weller, T.

    1977-01-01

    The applicability and adequacy of several computer techniques in predicting satisfactorily the nonlinear/inelastic response of angle ply laminates were evaluated. The analytical predictions were correlated with the results of a test program on the inelastic response under axial compression of a large variety of graphite-epoxy and boron-epoxy angle ply laminates. These comparison studies indicate that neither of the abovementioned analyses can satisfactorily predict either the mode of response or the ultimate stress value corresponding to a particular angle ply laminate configuration. Consequently, also the simple failure mechanisms assumed in the analytical models were not verified.

  18. Antibacterial activities effectuated by co-continuous epoxy-based polymer materials.

    PubMed

    Kubo, Takuya; Yasuda, Koji; Tominaga, Yuichi; Otsuka, Koji; Hosoya, Ken

    2013-07-01

    We report antibacterial activities of the epoxy-resin-based monolithic media (epoxy monoliths) having macroporous co-continuous structure as well as hydrophobic and/or hydrophilic surface. Utilizing epoxy monoliths containing ammonium groups, the antibacterial experiments were examined using Escherichia coli. As the results, the monolithic media prepared with an epoxy monomer having nitrogen atoms clearly showed antibacterial activities, while those prepared using the monomer without nitrogen atom showed less antibacterial activities. Additionally, the quaternization of the epoxy polymers were expressed significant antibacterial activities. Further studies elucidated that the observed antibacterial activities involved the steep effect based on pH changing of solution and hydrophobic interactions by the quaternary ammonium.

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

    PubMed

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

    2016-07-01

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

  20. Effect of fluorination on the mechanical behavior and electromagnetic interference shielding of MWCNT/epoxy composites

    NASA Astrophysics Data System (ADS)

    Lee, Si-Eun; Lee, Man Young; Lee, Min-Kyung; Jeong, Euigyung; Lee, Young-Seak

    2016-04-01

    Multi-walled carbon nanotube (MWCNT)/epoxy composites were prepared using MWCNT fluorinated to different extents. The mechanical properties, fracture surface morphologies and electromagnetic interference shielding efficiency (EMI-SE) of these composites were evaluated for epoxy matrices containing MWCNT with degrees of fluorination. The tensile strengths of the MWCNT/epoxy composites improved by 31% with treated MWCNT compared to that of the epoxy composites with untreated MWCNT. The EMI-SE values of the fluorinated MWCNT/epoxy composites improved up to 26% with increasing fluorination extent. The mechanical and electrical properties enhancement of the composites were attributed to the fluorinated MWCNT, which improved both the dispersion of the MWCNT in epoxy matrix and interfacial interactions between the MWCNT and the epoxy matrix.

  1. Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

    NASA Astrophysics Data System (ADS)

    Nazarenko, O. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder.

  2. Woven graphite epoxy composite test specimens with glass buffer strips

    NASA Technical Reports Server (NTRS)

    Bonnar, G. R.; Palmer, R. J.

    1982-01-01

    Woven unidirectional graphite cloth with bands of fiberglass replacing the graphite in discrete lengthwise locations was impregnated with epoxy resin and used to fabricate a series of composite tensile and shear specimens. The finished panels, with the fiberglass buffer strips, were tested. Details of the fabrication process are reported.

  3. Epoxy-crosslinked sulfonated poly (phenylene) copolymer proton exchange membranes

    DOEpatents

    Hibbs, Michael; Fujimoto, Cy H.; Norman, Kirsten; Hickner, Michael A.

    2010-10-19

    An epoxy-crosslinked sulfonated poly(phenylene) copolymer composition used as proton exchange membranes, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cell, in electrode casting solutions and electrodes, and in sulfur dioxide electrolyzers. These improved membranes are tougher, have higher temperature capability, and lower SO.sub.2 crossover rates.

  4. Photosensitive filler minimizes internal stresses in epoxy resins

    NASA Technical Reports Server (NTRS)

    Dillon, J. N.

    1967-01-01

    Photosensitive filler is added to curable epoxy resins to minimize stress from internal shrinkage during curing or polymerization. Cinnamic acid resins and cinnamal ketones may be added in the amount of 1 to 3 percent by weight of the resin mixture.

  5. Resistance of Plastics to Outdoor Weathering. Glass Filament Wound Epoxies.

    DTIC Science & Technology

    This report presents results on the aging and natural weathering of filament-wound, glass -reinforced epoxy resin systems for use as engineering...materials for Army rocket motor cases. Specimens (cylinders 9 inches long and 3 inches in diameter, using either E or S glass with various resin systems

  6. Thermal expansion of an epoxy-glass microsphere composite

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Burks, H. D.

    1977-01-01

    The thermal expansion of a composite of epoxy (diglycidyl ether of bisphenol A) and solid glass microspheres was investigated. The microspheres had surfaces which were either untreated or treated with a silicone release agent, an epoxy coupling agent, or a general purpose silane coupling agent. Both room temperature (about 300 K) and elevated temperature (about 475 K) cures were used for the epoxy. Two microsphere size ranges were used, about 50 microns, which is applicable in filled moldings, and about 125 microns, which is applicable as bond line spacers. The thermal expansion of the composites was measured from 300 to 350 K or from 300 to 500 K, depending on the epoxy cure temperature. Measurements were made on composites containing up to .6 volume fraction microspheres. Two predictive models, which required only the values of thermal expansion of the polymer and glass and their specific gravities, were tested against the experimental data. A finite element analysis was made of the thermal strain of a composite cell containing a single microsphere surrounded by a finite-thickness interface.

  7. New hybrid thermosets based on epoxy resins and benzocylobutenes

    SciTech Connect

    Brennan, D.J.; White, J.E.; Burks, B.T.

    1995-12-31

    A series of new, one component thermosets have been prepared by combining Dow`s epoxy resin and benzo-cyclobutene (BCB) technologies. The hybrid epoxy/BCB thermosetting monomers are prepared in the melt by reactions of amine-, phenol-, and carboxyl-functionalized benzocyclobutenes with epoxy-containing species such as bisphenol-A diglycidyl ether, chain-extended bisphenol-A epoxy resins, 9,9-bis(4-glycidyloxy-phenyl)fluorene, and epichlorohydrin. The monomers have outstanding processing characteristics, potentially long shelf life, and the convenience of an uncatalyzed, thermally cured, one component system. The resins are cured at >170{degrees}C (T{sub max}=260{degrees}C) and exhibit glass transition temperatures (Tg) of 85 to over 250{degrees}C. The examples shown below (n=0, 1, and 3.5) were prepared as part of this work. The chain extended species (n=3.5) is an extraordinarily tough thermoset, with a fracture toughness (K{sub Ic}) of over 3,000 psi-in{sup 0.5}.

  8. Viscoelastic Properties of Alkoxy Silane-Epoxy Interpenetrating Networks

    DTIC Science & Technology

    2003-11-01

    Owens Corning Fiberglass for supply of the epoxy film former emulsion used in the model silane formulation. The authors also wish to acknowledge the...inclusion filled composite µm- powderproperties 4 triblock copolymer surfactant. The Owens Corning Company generously provided the film former emulsion

  9. Multiscale Modeling of Graphite/CNT/Epoxy Hybrid Composites

    DTIC Science & Technology

    2016-03-09

    A - Approved for Public Release 13. SUPPLEMENTARY NOTES 14. ABSTRACT Incorporation of carbon nanotubes (CNTs) into epoxy-based composites for...materials with higher moduli and strength characteristics. 15. SUBJECT TERMS Molecular Dynamics, Carbon Nanotubes , Multi-scale Modeling, Micromechanics...Gregory M. Odegard Michigan Technological University Introduction This project was inspired from the AFOSR-sponsored workshop “ Nanotube

  10. Degradation free epoxy impregnation of REBCO coils and cables

    NASA Astrophysics Data System (ADS)

    Barth, C.; Bagrets, N.; Weiss, K.-P.; Bayer, C. M.; Bast, T.

    2013-05-01

    In applications utilizing high-temperature superconductors (HTS) under high mechanical loads as high-field magnets or rotors of generators and motors, the rare-earth-barium-copper-oxide (REBCO) tapes have to be stabilized mechanically. This is achieved using support structures of structural materials and filling the voids in the support through the impregnation of the tapes. The impregnation prevents movement of the tapes and distributes mechanical loads evenly. With high mechanical strengths and low sensitivities to rapid temperature changes, epoxy resins are desired materials for the impregnation of superconductor tapes. However, a strong decrease of the current-carrying capabilities was observed in previous epoxy-impregnated REBCO coils. In this work the thermal expansion mismatches between epoxy resins and REBCO tapes are identified as the cause of these degradations. Fillers are used to reduce the thermal expansions of glues and resins. Mixtures with varying filler contents are analyzed systematically. Their thermal expansions and the corresponding degradations of short REBCO tape samples are measured. A mixture of epoxy resin and filler is found which allows degradation-free impregnation of REBCO tapes. This mixture is validated on a 1.2 m long 15 × 5 Roebel-assembled-coated-conductor (RACC) cable from Industrial Research Limited (IRL).

  11. Molecular Dynamics Simulations of Adhesion at Epoxy Interfaces

    NASA Technical Reports Server (NTRS)

    Frankland, Sarah-Jane V.; Clancy, Thomas C.; Hinkley, J. A.; Gates. T. S.

    2008-01-01

    The effect of moisture on adhesives used in aerospace applications can be modeled with chemically specific techniques such as molecular dynamics simulation. In the present study, the surface energy and work of adhesion are calculated for epoxy surfaces and interfaces, respectively, by using molecular dynamics simulation. Modifications are made to current theory to calculate the work of adhesion at the epoxy-epoxy interface with and without water. Quantitative agreement with experimental values is obtained for the surface energy and work of adhesion at the interface without water. The work of adhesion agrees qualitatively with the experimental values for the interface with water: the magnitude is reduced 15% with respect to the value for the interface without water. A variation of 26% in the magnitude is observed depending on the water configuration at a concentration of 1.6 wt%. The methods and modifications to the method that are employed to obtain these values are expected to be applicable for other epoxy adhesives to determine the effects of moisture uptake on their work of adhesion.

  12. Tailored SWCNT functionalization optimized for compatibility with epoxy matrices

    NASA Astrophysics Data System (ADS)

    Martinez-Rubi, Y.; Gonzalez-Dominguez, J. M.; Ansón-Casaos, A.; Kingston, C. T.; Daroszewska, M.; Barnes, M.; Hubert, P.; Cattin, C.; Martinez, M. T.; Simard, B.

    2012-07-01

    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.

  13. Wave attenuation in thick graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Mal, A. K.; Bar-Cohen, Y.

    1992-01-01

    The mechanics of wave attenuation in thick graphite/epoxy composites is examined in order to facilitate interpretation of the wave amplitudes recorded in ultrasonic experiments. The values of a small number of parameters are determined through comparison between calculated and measured waveforms for four specimens. The agreement between the measured and calculated waveforms are shown to be excellent in all four cases.

  14. Environmental Testing of Glass-Fiber/Epoxy Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Faddoul, J. R.

    1987-01-01

    Pair of reports discusses long-term environmental tests of glassfiber/epoxy composite pressure vessels. Strength diminishes during long exposure to environment. Since such data necessary for accurate design of long-life structures such as pressure vessels, NASA Lewis Research Center built outdoor test stand in 1973. Test stand maintains system under constant pressure loading without frequent intervention of personnel.

  15. Novel epoxy activated hydrogels for solving lactose intolerance.

    PubMed

    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.

  16. Tribological behaviour of unidirectional carbon fibre-reinforced epoxy composites

    NASA Astrophysics Data System (ADS)

    Şahin, Y.; De Baets, P.

    2017-02-01

    Tribological behaviour of unidirectional carbon fibre-reinforced epoxy composites containing 42wt.% (CU42) and 52wt.% (CU52) carbon fibres fabricated by moulding technique was investigated on a pin-on-flat plate configuration. It is the first time to measure static and dynamic coefficient of frictions and wear rates of epoxy composites under heavy loading conditions. Microstructures of composites were examined by scanning electron microscopy (SEM). The experimental results indicated the carbon fiber improved the tribological properties of thermoset epoxy by reducing wear rate, but increased the coefficient of friction. At higher load, average wear rates were about 10.8x10-5 mm3/N.m for composites while it was about 38.20x10-5 mm3/N.m for epoxy resin. The wear rate decreased with decreasing load while friction coefficient increased with decreasing load. Moreover, friction coefficient of composites of CU42 tested at 90 N load was measured to be in the range 0.35 and 0.13 for static and dynamic component, respectively.

  17. Impact of a heteroatom in a structure-activity relationship study on analogues of phenyl glycidyl ether (PGE) from epoxy resin systems.

    PubMed

    Niklasson, Ida B; Delaine, Tamara; Luthman, Kristina; Karlberg, Ann-Therese

    2011-04-18

    Epoxy resins are among the most common causes of occupational contact dermatitis. They are normally used in so-called epoxy resin systems (ERS). These commercial products are combinations of epoxy resins, curing agents, modifiers, and reactive diluents. The most frequently used resins are diglycidyl ethers based on bisphenol A (DGEBA) and bisphenol F (DGEBF). In this study, we have investigated the contact allergenic properties of a series of analogues to the reactive diluent phenyl glycidyl ether (PGE), all with similar basic structures but with varying heteroatoms or with no heteroatom present. The chemical reactivity of the compounds in the test series toward the hexapeptide H-Pro-His-Cys-Lys-Arg-Met-OH was investigated. All epoxides were shown to bind covalently to both cysteine and proline residues. The percent depletion of nonreacted peptide was also studied resulting in ca. 60% depletion when using either PGE, phenyl 2,3-epoxypropyl sulfide (2), or N-(2,3-epoxypropyl)aniline (3), and only 15% when using 1,2-epoxy-4-phenylbutane (4) at the same time point. The skin sensitization potencies of the epoxides using the murine local lymph node assay (LLNA) were evaluated in relation to the observed physicochemical and reactivity properties. To enable determination of statistical significance between structurally closely related compounds, a nonpooled LLNA was performed. It was found that all investigated compounds containing a heteroatom in the α-position to the epoxide were strong sensitizers, congruent with the reactivity data, indicating that the impact of a heteroatom is crucial for the sensitizing capacity for this type of epoxides.

  18. TRIFLUOROMETHYL COMPOUNDS OF GERMANIUM

    DTIC Science & Technology

    FLUORIDES, *GERMANIUM COMPOUNDS, *HALIDES, *ORGANOMETALLIC COMPOUNDS, ALKYL RADICALS, ARSENIC COMPOUNDS, CHEMICAL BONDS, CHEMICAL REACTIONS ...CHLORIDES, CHLORINE COMPOUNDS, HYDROLYSIS, IODIDES, METHYL RADICALS, POTASSIUM COMPOUNDS, PYROLYSIS, STABILITY, SYNTHESIS, TIN COMPOUNDS.

  19. Preparation and Various Characteristics of Epoxy/Alumina Nanocomposites

    NASA Astrophysics Data System (ADS)

    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.

  20. Education And Public Outreach For NASA's EPOXI Mission

    NASA Astrophysics Data System (ADS)

    McFadden, Lucy-Ann A.; Warner, E. M.; Crow, C. A.; Ristvey, J. D.; Counley, J.

    2008-09-01

    NASA's EPOXI mission has two scientific objectives in using the Deep Impact flyby spacecraft for further studies of comets and adding studies of extra-solar planets around other stars. During the Extrasolar Planetary Observations and Characterization (EPOCh) phase of the mission, observations of extrasolar planets transiting their parent stars are observed to further knowledge and understanding of planetary systems. Observations of Earth allow for comparison with Earth-like planets around other stars. A movie of Earth during a day when the Moon passed between Earth and the spacecraft is an educational highlight with scientific significance. The Deep Impact Extended Investigation (DIXI) continues the Deep Impact theme of investigating comets with a flyby of comet Hartley 2 in November 2010 to further explore the properties of comets and their formation. The EPOXI Education and Public Outreach (E/PO) program builds upon existing materials related to exploring comets and the Deep Impact mission, updating and modifying activities based on results from Deep Impact. An educational activity called Comparing Comets is under development that will guide students in conducting analyses similar to those that DIXI scientists will perform after observing comet Hartley 2. Existing educational materials related to planet finding from other NASA programs are linked from EPOXI's web page. Journey Through the Universe at the National Air and Space Museum encourages education in family and community groups and reaches out to underrepresented minorities. EPOXI's E/PO program additionally offers a newsletter to keep the public, teachers, and space enthusiasts apprised of mission activities. For more information visit: http://epoxi.umd.edu.

  1. New antitumor compounds from Carya cathayensis.

    PubMed

    Wu, Wei; Bi, Xiu-Li; Cao, Jia-Qing; Zhang, Kai-Qing; Zhao, Yu-Qing

    2012-03-01

    A new lignan (7R,8S,8'R)-4,4',9-trihydroxy-7,9'-epoxy-8,8'-lignan, and three new phenolics, carayensin-A, carayensin-B, and carayensin-C, together with 13 known compounds were isolated from the shells of Carya cathayensis. Their chemical structures were established mainly by 1D and 2D NMR techniques and mass spectrometry. All the compounds were evaluated for cytotoxicity against several human tumor types including human colorectal cancer cell lines (HCT-116, HT-29), human lung cancer cell line (A549), and human breast cancer cell line (MCF-7). The compounds 1, 5, 6, and 16 are considered to be potential as antitumor agents, which could significantly inhibit the cancer cell growth in a dose-dependent manner.

  2. Synthesis and properties of a bio-based epoxy resin with high epoxy value and low viscosity.

    PubMed

    Ma, Songqi; Liu, Xiaoqing; Fan, Libo; Jiang, Yanhua; Cao, Lijun; Tang, Zhaobin; Zhu, Jin

    2014-02-01

    A bio-based epoxy resin (denoted TEIA) with high epoxy value (1.16) and low viscosity (0.92 Pa s, 258C) was synthesized from itaconic acid and its chemical structure was confirmed by 1H NMR and 13C NMR spectroscopy. Its curing reaction with poly(propylene glycol) bis(2-aminopropyl ether) (D230) and methyl hexahydrophthalic anhydride (MHHPA) was investigated. For comparison, the commonly used diglycidyl ether of bisphenol A (DGEBA) was also cured with the same curing agents. The results demonstrated that TEIA showed higher curing reactivity towards D230/MHHPA and lower viscosity compared with DGEBA, resulting in the better processability. Owing to its high epoxy value and unique structure, comparable or better glass transition temperature as well as mechanical properties could be obtained for the TEIA-based network relative to the DGEBA-based network. The results indicated that itaconic acid is a promising renewable feedstock for the synthesis of bio-based epoxy resin with high performance.

  3. Synthesis, Characterization, and Cross-Linking Strategy of a Quercetin-Based Epoxidized Monomer as a Naturally-Derived Replacement for BPA in Epoxy Resins.

    PubMed

    Kristufek, Samantha L; Yang, Guozhen; Link, Lauren A; Rohde, Brian J; Robertson, Megan L; Wooley, Karen L

    2016-08-23

    The natural polyphenolic compound quercetin was functionalized and cross-linked to afford a robust epoxy network. Quercetin was selectively methylated and functionalized with glycidyl ether moieties using a microwave-assisted reaction on a gram scale to afford the desired monomer (Q). This quercetin-derived monomer was treated with nadic methyl anhydride (NMA) to obtain a cross-linked network (Q-NMA). The thermal and mechanical properties of this naturally derived network were compared to those of a conventional diglycidyl ether bisphenol A-derived counterpart (DGEBA-NMA). Q-NMA had similar thermal properties [i.e., glass transition (Tg ) and decomposition (Td ) temperatures] and comparable mechanical properties (i.e., Young's Modulus, storage modulus) to that of DGEBA-NMA. However, it had a lower tensile strength and higher flexural modulus at elevated temperatures. The application of naturally derived, sustainable compounds for the replacement of commercially available petrochemical-based epoxies is of great interest to reduce the environmental impact of these materials. Q-NMA is an attractive candidate for the replacement of bisphenol A-based epoxies in various specialty engineering applications.

  4. Thermal degradation of new and aged urethane foam and epon 826 epoxy.

    SciTech Connect

    Kruizenga, Alan Michael; Mills, Bernice E.

    2013-08-01

    Thermal desorption spectroscopy was used to monitor the decomposition as a function of temperature for the foam and epoxy as a function of temperature in the range of 60C to 170C. Samples were studied with one day holds at each of the studied temperatures. Both new (FoamN and EpoxyN) and aged (FoamP and EpoxyP) samples were studied. During these ~10 day experiments, the foam samples lost 11 to 13% of their weight and the EpoxyN lost 10% of its weight. The amount of weight lost was difficult to quantify for EpoxyP because of its inert filler. The onset of the appearance of organic degradation products from FoamP began at 110C. Similar products did not appear until 120C for FoamN, suggesting some effect of the previous decades of storage for FoamP. In the case of the epoxies, the corresponding temperatures were 120C for EpoxyP and 110C for EpoxyN. Suggestions for why the aged epoxy seems more stable than newer sample include the possibility of incomplete curing or differences in composition. Recommendation to limit use temperature to 90-100C for both epoxy and foam.

  5. Cure reaction of epoxy resins catalyzed by graphite-based nanofiller

    NASA Astrophysics Data System (ADS)

    Corcione, C. Esposito; Acocella, Maria Rosaria; Giuri, Antonella; Maffezzoli, Alfonso; Guerra, Gaetano

    2015-12-01

    A significant effort was directed to the synthesis of graphene stacks/epoxy nanocomposites and to the analysis of the effect of a graphene precursor on cure reaction of a model epoxy matrix. A comparative thermal analysis of epoxy resins filled with an exfoliated graphite oxide eGO were conducted. The main aim was to understand the molecular origin of the influence of eGO on the Tg of epoxy resins. The higher Tg values previously observed for low curing temperatures, for epoxy resins with graphite-based nanofillers, were easily rationalized by a catalytic activity of graphitic layers on the reaction between the epoxy and amine groups of the resin, which leads to higher crosslinking density in milder conditions. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based filler was performed by isothermal DSC measurements. The DSC results showed that the addition of graphite based filler greatly increased the enthalpy of epoxy reaction and the reaction rate, confirming the presence of a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine). A kinetic modelling analysis, arising from an auto-catalyzed reaction mechanism, was finally applied to isothermal DSC data, in order to predict the cure mechanism of the epoxy resin in presence of the graphite based nanofiller.

  6. Study made to control depth of potting compound for honeycomb sandwich fasteners

    NASA Technical Reports Server (NTRS)

    Cushman, J.

    1966-01-01

    Study determines optimum fastener insert size and shape, type of embedding cement, diameter, undercut and depth control by fiber glass plug in a honeycomb structure for maximum tensile strength The best potting compound is 5-5-1 weight mixture of epoxy resin, curing agent, and milled glass fibers.

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

    PubMed

    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.

  8. Fracture behavior of block copolymer and graphene nanoplatelet modified epoxy and fiber reinforced/epoxy polymer composites

    NASA Astrophysics Data System (ADS)

    Kamar, Nicholas T.

    Glass and carbon fiber reinforced/epoxy polymer composites (GFRPs and CFRPs) have high strength-to-weight and stiffness-to-weight ratios. Thus, GFRPs and CFRPs are used to lightweight aircraft, marine and ground vehicles to reduce transportation energy utilization and cost. However, GFRP and CFRP matrices have a low resistance to crack initiation and propagation; i.e. they have low fracture toughness. Current methods to increase fracture toughness of epoxy and corresponding GFRP and CFRPs often reduce composite mechanical and thermomechanical properties. With the advent of nanotechnology, new methods to improve the fracture toughness and impact properties of composites are now available. The goal of this research is to identify the fracture behavior and toughening mechanisms of nanoparticle modified epoxy, GFRPs and CFRPs utilizing the triblock copolymer poly(styrene)-block-poly(butadiene)-block-poly(methylmethacrylate) (SBM) and graphene nanoplatelets (GnPs) as toughening agents. The triblock copolymer SBM was used to toughen the diglycidyl ether of bisphenol-A (DGEBA) resin cured with m-phenylenediamine (mPDA) and corresponding AS4-12k CFRPs. SBM self assembled in epoxy to form nanostructured domains leading to larger increases in fracture toughness, KQ (MPa*m 1/2) than the traditional, phase separating carboxyl-terminated butadiene-acrylonitrile (CTBN) rubber. Additionally, SBM increased the mode-I fracture toughness, GIc (J/m2) of CFRPs without corresponding reductions in composite three-point flexural properties and glass transition temperature (Tg). Fractography of SBM modified epoxy and CFRPs via scanning electron microscopy (SEM) showed that sub 100 nm spherical micelles cavitated to induce void growth and matrix shear yielding toughening mechanisms. Furthermore, SBM did not suppress epoxy Tg, while CTBN decreased Tg with both increasing concentration and acrylonitrile content. Graphene nanoplatelets (GnPs) consist of a few layers of graphene sheets, which

  9. Relaxation Characteristics of 828 DGEBA Epoxy Over Long Time Periods

    NASA Astrophysics Data System (ADS)

    Hoo, Jasmine; Reprogle, Riley C.; Wisler, Brian; Arechederra, Gabriel K.; McCoy, John D.; Kropka, Jamie M.; Long, Kevin N.

    The mechanical relaxation response in uniaxial compression of a diglycidyl ether of bisphenol-A epoxy was studied over long time periods. The epoxy, 828DEA, was Epon 828 cured with diethanolamine (DEA). A sample was compressed at constant strain rate and held at various strain levels for days to allow the sample to relax. The sample was then compressed further and held once more. The relaxation curves were fit with a stretched exponential function. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  10. Development of failure criterion for Kevlar-epoxy fabric laminates

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Elliott, W. G.

    1984-01-01

    The development of the tensor polynomial failure criterion for composite laminate analysis is discussed. In particular, emphasis is given to the fabrication and testing of Kevlar-49 fabric (Style 285)/Narmco 5208 Epoxy. The quadratic-failure criterion with F(12)=0 provides accurate estimates of failure stresses for the Kevlar/Epoxy investigated. The cubic failure criterion was re-cast into an operationally easier form, providing the engineer with design curves that can be applied to laminates fabricated from unidirectional prepregs. In the form presented no interaction strength tests are required, although recourse to the quadratic model and the principal strength parameters is necessary. However, insufficient test data exists at present to generalize this approach for all undirectional prepregs and its use must be restricted to the generic materials investigated to-date.

  11. Study on voids of epoxy matrix composites sandwich structure parts

    NASA Astrophysics Data System (ADS)

    He, Simin; Wen, Youyi; Yu, Wenjun; Liu, Hong; Yue, Cheng; Bao, Jing

    2017-03-01

    Void is the most common tiny defect of composite materials. Porosity is closely related to composite structure property. The voids forming behaviour in the composites sandwich structural parts with the carbon fiber reinforced epoxy resin skins was researched by adjusting the manufacturing process parameters. The composites laminate with different porosities were prepared with the different process parameter. The ultrasonic non-destructive measurement method for the porosity was developed and verified through microscopic examination. The analysis results show that compaction pressure during the manufacturing process had influence on the porosity in the laminate area. Increasing the compaction pressure and compaction time will reduce the porosity of the laminates. The bond-line between honeycomb core and carbon fiber reinforced epoxy resin skins were also analyzed through microscopic examination. The mechanical properties of sandwich structure composites were studied. The optimization process parameters and porosity ultrasonic measurement method for composites sandwich structure have been applied to the production of the composite parts.

  12. Autonomic Healing of Epoxy Using Micro-Encapsulated Dicyclopentadiene

    SciTech Connect

    THOMA, STEVEN G.; GIUNTA, RACHEL K.; STAVIG, MARK E.; EMERSON, JOHN A.; MORALES, ALFREDO M.

    2003-05-01

    The autonomic healing ability of an epoxy adhesive containing micro-encapsulated dicyclopentadiene (DCPD) was evaluated. The epoxy resin used was Epon 828 cured with either Versamid 140 or diethylenetriamine (DETA). Variables included total weight percent of microcapsules (MCs) and catalyst, as well as the catalyst to DCPD ratio. The degree of healing was determined by the fracture toughness before and after ''healing'' using double-cantilever beam analysis. It was found that the degree of self-healing was most directly related to the contact area (i.e. crack width) during healing. Temperature also played a significant role. Observed differences between the results of this study and those in literature are discussed.

  13. Epoxy composites based on inexpensive tire waste filler

    SciTech Connect

    Ahmetli, Gulnare Gungor, Ahmet Kocaman, Suheyla

    2014-05-15

    Tire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young’s modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites.

  14. Dielectric properties of epoxy resin fly ash composite

    NASA Astrophysics Data System (ADS)

    Pattanaik, A.; Bhuyan, S. K.; Samal, S. K.; Behera, A.; Mishra, S. C.

    2016-02-01

    Epoxy resin is widely used as an insulating material in high voltage applications. Ceramic fillers are always added to the polymer matrix to enhance its mechanical properties. But at the same time, filler materials decreases the electrical properties. So while making the fly ash epoxy composite, it is obvious to detect the effect of fly ash reinforcement on the dielectric nature of the material. In the present research work, fly ash is added to four different weight percentages compositions and post-curing has been done in the atmospheric condition, normal oven and micro oven. Tests were carried out on the developed polymer composite to measure its dielectric permittivity and tan delta value in a frequency range of 1 Hz - 1 MHz. The space charge behaviours were also observed by using the pulse electroacoustic (PEA) technique. The dielectric strength and losses are compared for different conditions.

  15. Degradation of graphite-epoxy due to electron radiation

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.; Fox, D. J.; Sykes, G. F.

    1988-01-01

    Experimental results are presented showing that electron irradiation has a variable effect on the properties of graphite-epoxy depending upon the test temperature and the property of interest. In general, compression properties are improved at cold temperature and degraded at elevated temperature. With the exception of some moduli, tensile and shear properties are degraded at both cold and elevated temperatures. Electron irradiation lowers the glass transition temperature of graphite/epoxy significantly. Property degradation of irradiated materials at the elevated temperature is associated with the reduction in Tg. It is shown that a (0) compression-strength test is the most sensitive test for exhibiting the effects of electron irradiation. Results from tests on neat resin also show that the bulk matrix is degraded after irradiation, and that the correlation between resin and composite response is good.

  16. Pyrolysis of epoxies used for thermal-battery headers

    SciTech Connect

    Guidotti, R.A.; Thornberg, S.M.; Campbell-Domme, B.

    1995-08-01

    Thermally activated batteries use an epoxy for encapsulation of the electrical feedthroughs in the header of the battery. When the thermal battery is thermally abused, the encapsulant can pyrolyze and generate large internal pressures. This causes the battery to vent in extreme cases. The nature of these gases has never been adequately documented. Therefore, a study was undertaken to address this deficiency. The pyrolysis of various encapsulants that have been used, or are being considered for use, in thermally activated batteries was studied over a temperature range of 155 to 455 C. The composition of the pyrolysis decomposition products was determined by gas chromatography/mass spectrometry (GS/MS). This determination is helpful in assessing the potential environmental and health effect for personnel exposed to such gases. In addition, the thermal stability of the various epoxies was measured by thermogravimetric analysis (TGA).

  17. Tensile stress acoustic constants of unidirectional graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.

    1990-01-01

    Previously, the stress acoustic constants (SACs) of unidirectional graphite/epoxy composites were measured to determine the nonlinear moduli of this material. These measurements were made under compressive loading in order to obtain the sufficient number of values needed to calculate these moduli. However, because their strength in tension along fiber directions can be several times greater, most composites are used under tensile loading. Thus, it is important to characterize the nonlinear properties of these materials in tension as well. The SACs which are defined as the slope of the normalized change in ultrasonic 'natural' velocity as a function of stress were measured in a unidirectional laminate of T300/5208 graphite/epoxy. Tensile load was applied along the fiber axis with the ultrasonic waves propagating perpendicular to the fiber direction. Changes in velocity were measured using a pulsed phase locked loop ultrasonic interferometer with the nominal frequency of the ultrasonic waves being 2.25 MHz.

  18. Tensile Stress Acoustic Constants of Unidirectional Graphite/Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.

    1990-01-01

    Previously, the stress acoustic constants (SAC's) of unidirectional graphite/epoxy composites were measured to determine the nonlinear moduli of this material. These measurements were made under compressive loading in order to obtain the sufficient number of values needed to calculate these moduli. However, because their strength in tension along fiber directions can be several times greater, most composites are used under tensile loading. Thus, it is important to characterize the nonlinear properties of these materials in tension as well. The SAC's which are defined as the slope of the normalized change in ultrasonic "natural" velocity as a function of stress were measured in a unidirectional laminate of T300/5208 graphite/epoxy. Tensile load was applied along the fiber axis with the ultrasonic waves propagating perpendicular to the fiber direction. Changes in velocity were measured using a pulsed phase locked loop ultrasonic interferometer with the nominal frequency of the ultrasonic waves being 2.25 MHz.

  19. Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites.

    PubMed

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

    2014-01-01

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

  20. Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites.

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  1. Formulation and Characterization of Epoxy Resin Copolymer for Graphite Composites

    NASA Technical Reports Server (NTRS)

    Keck, F. L.

    1983-01-01

    Maximum char yield was obtained with a copolymer containing 25% mol fraction DGEBE and 75% mol fraction DGEBA (Epon 828). To achieve the high values (above 40%), a large quantity of catalyst (trimethoxyboroxine) was necessary. Although a graphite laminate 1/8" thick was successfully fabricated, the limited life of the catalyzed epoxy copolymer system precludes commercial application. Char yields of 45% can be achieved with phenolic cured epoxy systems as indicated by data generated under NAS2-10207 contract. A graphite laminate using this type of resin system was fabricated for comparison purposes. The resultant laminate was easier to process and because the graphite prepreg is more stable, the fabrication process could readily be adapted to commercial applications.

  2. Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites

    PubMed Central

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

    2014-01-01

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

  3. Discrimination of Epoxy Curing by High Lamb Modes Order

    NASA Astrophysics Data System (ADS)

    Gauthier, Camille; Leduc, Damien; Galy, Jocelyne; Elkettani, Mounsif Echherif; Izbicki, Jean-Louis

    This work is a contribution to the non destructive testing of structural adhesive bonding by ultrasonic methods. The aim of this paper is to link acoustic behaviors of epoxy bulk samples to their level of cure, quantified by a partial or a total epoxy conversion. The bulk longitudinal and shear waves velocities are measured for each sample. They are used to determine the theoretical dispersion curves of Lamb waves. Theoretical results predict a high sensitivity of some high order Lamb modes to the cure level by the variation of their wavenumber, for a given mode and for the same frequency range. In parallel, an experimental study is conducted to determine the experimental dispersion curves. The experimental results and the predicted ones are in a good agreement.

  4. Bending response of Kevlar 49/epoxy beams and rings

    SciTech Connect

    Reedy, E.D. Jr.; Guess, T.R.

    1988-01-01

    Kevlar 49/epoxy laminates often exhibit substantial material nonlinearity when subjected to bending. A unidirectionally reinforced Kevlar 49 lamina is nearly linear elastic to failure in tension, however, in fiber-directed compression, it responds in a perfectly plastic-like manner once a compressive strength of roughly 20% of its tensile ultimate strength is exceeded. This combined linear tensile/nonlinear compressive behavior is the source of Kevlar 49/epoxy's flexural nonlinearity. Since Kevlar 49 reinforced laminates can often carry bending loads well above those needed to cause initial compressive yield, it is desirable to be able to predict the post-yield flexural response. In this presentation, analyses that utilize a simple idealization of compressive yielding are described and calculated results for Kevlar 49 reinforced beams and rings are compared with available data. 2 refs., 3 figs.

  5. Sliding wear resistance of epoxy polymers against stainless steel

    SciTech Connect

    Spinks, G.M.; Dimovski, L.; Samandi, M.

    1993-12-31

    The wear mechanisms occurring during sliding contact between epoxy resins and a smooth steel counterface have been investigated. The samples were prepared from a commercial diglycidyl ether of bisphenol-A epoxy and cured with various hardeners. The cured resins displayed a wide range of mechanical properties (particularly fracture toughness), and crosslink densities. The wear rates of the samples were found to vary by up to four orders of magnitude. It was found that the wear rates correlated to the inverse of the fracture toughness, which was in accord with previous studies on the wear of plastics by Omar et al. The mechanism was found to involve an ``adhesive/fatigue`` process, as proposed by Omar. Additionally, it was found that the addition of a rubber toughening agent had no effect on the wear rate, whilst sliding contact between polymer and polymer resulted in a much higher rate of wear. Possible explanations for this behavior are given.

  6. Effect of electron beam irradiation on thermal and mechanical properties of epoxy polymer

    NASA Astrophysics Data System (ADS)

    Nguyen, A. T.; Visakh, P. M.; Nazarenko, O. B.; Chandran, C. S.; Melnikova, T. V.

    2017-01-01

    This study investigates the thermal and mechanical properties of epoxy polymer after exposure to different doses of electron beam irradiation. The epoxy polymer was prepared using epoxy-diane resin ED-20 cured by polyethylenepolyamine. The irradiation of the samples was carried out with doses of 30, 100 and 300 kGy. The effects of doses on thermal and mechanical properties of the epoxy polymer were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The thermal properties of the epoxy polymer slightly increased after irradiation at the heating in air. The tensile strength and Young’s modulus of the epoxy polymer increased by the action of electron beam up to dose of 100 kGy and then decreased. The elongation at break decreased with increasing the irradiation dose.

  7. Fracto-emission from graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Dickinson, J. T.

    1983-01-01

    Fracto-emission (FE) is the emission of particles and photons during and following crack propagation. Electrons (EE), positive ions (PIE), and excited and ground state neutrals (NE) were observed. Results of a number of experiments involving principally graphite/epoxy composites and Kevlar single fibers are presented. The physical processes responsible for EE and PIE are discussed as well as FE from fiber- and particulate-reinforced composites.

  8. Toughening reinforced epoxy composites with brominated polymeric additives

    NASA Technical Reports Server (NTRS)

    Nir, Z.; Gilwee, W. J., Jr. (Inventor)

    1985-01-01

    Cured polyfunctional epoxy resins including tris (hydroxyphenyl) methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy terminated butadiene acrylonitrile rubber is optionally present in the precure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon reinforced composites, of these resins are disclosed and shown to have improved toughness.

  9. Healing efficiency of epoxy-based materials for structural application

    NASA Astrophysics Data System (ADS)

    Raimondo, Marialuigia; Guadagno, Liberata

    2012-07-01

    This paper describes a self-healing composite exhibiting high levels of healing efficiency under working conditions typical of aeronautic applications. The self-healing material is composed of a thermosetting epoxy matrix in which a catalyst of Ring Opening Metathesis Polymerization (ROMP) and nanocapsules are dispersed. The nanocapsules contain a monomer able to polymerize via ROMP. The preliminary results demonstrate an efficient self-repair function which is also active at very low temperatures.

  10. Static and dynamic response of graphite-epoxy curved frames

    NASA Technical Reports Server (NTRS)

    Collins, J. S.; Johnson, E. R.

    1990-01-01

    Experiments were conducted to measure the three-dimensional static and vibratory response of two graphite-epoxy, thin-walled, open section frames. The frames are semicircular with a radius of three feet. One specimen had an I cross section and the other had a channel cross section. The experimental data is used to evaluate a mixed finite element model of the frames that is based on Vlasov-type, thin-walled, open section curved beam theory.

  11. Bonding and impedance matching of acoustic transducers using silver epoxy.

    PubMed

    Son, Kyu Tak; Lee, Chin C

    2012-04-01

    Silver epoxy was selected to bond transducer plates on glass substrates. The properties and thickness of the bonding medium affect the electrical input impedance of the transducer. Thus, the thickness of the silver epoxy bonding layer was used as a design parameter to optimize the structure for the transducer input impedance to match the 50 Ω output impedance of most radio frequency (RF) generators. Simulation and experimental results show that nearly perfect matching is achieved without using any matching circuit. At the matching condition, the transducer operates at a frequency band a little bit below the half-wavelength resonant frequency of the piezoelectric plate. In experiments, lead titanate (PT) piezoelectric plates were employed. Both full-size, 11.5 mm × 2 mm × 0.4 mm, and half-size, 5.75 mm × 2 mm × 0.4 mm, can be well matched using optimal silver epoxy thickness. The transducer assemblies demonstrate high efficiency. The conversion loss from electrical power to acoustic power in soda-lime glass is 4.3 dB. This loss is low considering the fact that the transducers operate at off-resonance by 12%. With proper choice of silver epoxy thickness, the transducer can be matched at the fundamental, the 3rd and 5th harmonic frequencies. This leads to the possible realization of triple-band transducers. Reliability was assessed with thermal cycling test according to Telcordia GR-468-Core recommendation. Of the 30 transducer assemblies tested, none broke until 2900 cycles and 27 have sustained beyond 4050 cycles.

  12. Model Adherend Surface Effects on Epoxy Cure Reactions

    DTIC Science & Technology

    1990-11-01

    of X-ray photoelectro spectroscopy and reflection absorption infrarcd spectroscopy. They concluded that the catalytic action of the acidic hydroxyl...that an acidic carbon surface (produced by oxidation) resulted in selective amine adsorption and the catalytic acceleration of its reaction with the...subject of this report. EXPERIMENTAL The epoxy resins used in this study consisted of Epon 826, a diglycidyl ether of bisphenol A ( DGEBA ) resin (Shell

  13. MICROMECHANICS IN CONTINOUS GRAPHITE FIBER/EPOXY COMPOSITES DURING CREEP

    SciTech Connect

    C. ZHOU; ET AL

    2001-02-01

    Micro Raman spectroscopy and classic composite shear-lag models were used to analyze the evolution with time of fiber and matrix strain/stress around fiber breaks in planar model graphite fiber-epoxy matrix composites. Impressive agreements were found between the model predictions and the experimental results. The local matrix creep leads to an increase in the load transfer length around the break under a constant load. This increases the chance of fiber breakage in the neighboring intact fibers.

  14. Interdiffusion at the interface between poly(vinylpyrrolidone) and epoxy

    SciTech Connect

    Oyama, H.T.; Wightman, J.P.; Lesko, J.J.; Reifsnider, K.L.

    1996-12-31

    The study of polymer-polymer interfaces is recently attracting great interest. So far, most studies have focused on the interface between thermoplastic polymers, even though the interface between thermoplastic and thermoset polymers is also very important in numerous areas such as adhesion and composites. In the present study, bilayer films of thermoplastic poly(vinylpyrrolidone) and a thermoset epoxy were prepared and their compositional profiles at the interface were examined by electron microprobe analysis.

  15. RADIATION EFFECTS ON EPOXY/CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E; Eric Skidmore, E

    2008-12-12

    The Department of Energy Savannah River Site vitrifies nuclear waste incident to defense programs through its Defense Waste Processing Facility (DWPF). The piping in the DWPF seal pot jumper configuration must withstand the stresses during an unlikely but potential deflagration event, and maintain its safety function for a 20-year service life. Carbon fiber-reinforced epoxy composites (CFR) were proposed for protection and reinforcement of piping during such an event. The proposed CFR materials have been ASME-approved (Section XI, Code Case N-589-1) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. The proposed carbon fiber/epoxy composite reinforcement system was originally developed for pipeline rehabilitation and post-construction maintenance in petrochemical, refineries, DOT applications and other industries. The effects of ionizing radiation on polymers and organic materials have been studied for many years. The majority of available data are based on traditional exposures to gamma irradiation at high dose rates ({approx}10,000 Gy/hr) allowing high total dose within reasonable test periods and general comparison of different materials exposed at such conditions. However, studies in recent years have shown that degradation of many polymers are sensitive to dose rate, with more severe degradation often observed at similar or even lower total doses when exposed to lower dose rates. This behavior has been primarily attributed to diffusion-limited oxidation which is minimized during very high dose rate exposures. Most test standards for accelerated aging and nuclear qualification of components acknowledge these limitations. The results of testing to determine the radiation resistance and microstructural effects of gamma irradiation exposure on a bisphenol-A based epoxy matrix composite reinforced with carbon fibers are presented. This work provides a foundation for a more extensive evaluation of dose rate effects on advanced epoxy

  16. Pulsed NMR study of the curing process of epoxy resin.

    PubMed

    Kimoto, Hiroki; Tanaka, Chikako; Yaginuma, Michiko; Shinohara, Emi; Asano, Atsushi; Kurotsu, Takuzo

    2008-07-01

    To analyze a curing process of epoxy resin in terms of molecular motion, we adapted a pulsed NMR method. Three kinds of (1)H spin-spin relaxation times (T(2L) (long), T(2S) (short) and T(2M) (intermediate)) were estimated from observed solid echo train signals as the curing process proceeded. A short T(2S) value below 20 micros suggests the existence of a motion-restricted chain, that is, cured elements of resin, and its fraction, P(S), sigmoidally increased with the curing time. On the other hand, the fraction of T(2L), P(L), decreased with the reaction time reciprocally against P(S), suggesting the disappearance of highly mobile molecules raised from pre-cured resin. The spin-lattice relaxation time, T(1), was also measured to check another aspect of molecular motion in the process. T(1) of the mixed epoxy resin and curing agent gradually increased just after mixing both of them. This corresponds to an increment of a less-mobile fraction, of which the correction time is more than 10(-6) s, and also means that the occurrence of a network structure whose mobility is strongly restricted by chemically bonded bridges between the epoxy resin and curing agent. The time courses of these parameters coincided with those of IR peaks pertinent to the curing reaction. Therefore, pulsed NMR is a useful tool to monitor the hardening process of epoxy resin in real time non-distractively in terms of the molecular motion of protons.

  17. Toughening reinforced epoxy composites with brominated polymeric additives

    NASA Technical Reports Server (NTRS)

    Nir, Z. (Inventor); Gilwee, W. J., Jr. (Inventor)

    1985-01-01

    Cured polyfunctional epoxy resins including tris(hydroxyphenyl)methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy-terminated butadiene-acrylonitrile rubber is optionally present in the pre-cure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon-reinforced composites, of these resins are disclosed and shown to have improved toughness.

  18. Fabrication and evaluation of uniform and gradient density epoxies

    SciTech Connect

    Domeier, L.A.; Skala, D.M.; Goods, S.H.

    1997-11-01

    Filled epoxy materials which vary in density in a designed manner have been fabricated and their mechanical properties evaluated. Density variations were produced by incorporating different volume fractions of either glass microballoons (GMB) or alumina. Several different sample types were evaluated including uniform density (0.8 g/cm{sup 3} < {rho} < 2.0 g/cm{sup 3}) samples and gradient density samples (GMB only, 0.8 g/cm{sup 3} < {rho} < 1.2 g/cm{sup 3}). The uniform density specimens were evaluated for the effects of filler type and concentration on modulus and toughness. Results indicated that addition of alumina filler significantly increased the resulting modulus while addition of GMB had little measurable effect. These differences could be understood in terms of the differing moduli of the additives relative to that of the epoxy matrix. In the former case the alumina particulates had a modulus much greater than that of the epoxy while in the latter case, the modulus of the GMB additive was only slightly greater than that of the matrix. Addition of either filler significantly degraded the toughness of the composite specimens and precluded the use of gradients to enhance toughness performance. Discontinuous {open_quotes}block{close_quotes} gradients used for testing were fabricated by simple sequential pours of formulations with different GMB loadings and were evaluated for modulus, strength and ductility. Continuous gradients were fabricated in process studies by programmed shifts in the peristaltic pumping/mixing ratio of epoxies filled with either alumina or GMB. None of the continuous gradient materials were mechanically tested. These results suggest that applications utilizing gradient materials containing alumina and similar high modulus fillers to provide designed stiffness rather than improved toughness are the most appropriate targets for future investigation.

  19. Mechanical properties of henequen fibre/epoxy resin composites

    NASA Astrophysics Data System (ADS)

    Gonzalez-Murillo, C.; Ansell, M. P.

    2009-07-01

    By using surface-treated and untreated henequen fibres and an epoxy resin, composites were made by compression moulding, and their mechanical properties and failure modes were determined experimentally in tension, bending, and impact loading. The results obtained show that the treatment of fibre surface does not improve the bond between the fibres and the resin matrix, and the general mechanical properties of the composites are similar.

  20. Novel epoxy formulations for high energy radiation curable composites

    NASA Astrophysics Data System (ADS)

    Spadaro, G.; Calderaro, E.; Tomarchio, E.; Dispenza, C.

    2005-03-01

    It has been widely recognised that high energy radiation can be effectively applied to the cure of epoxy resins in applications as composite matrices or structural adhesives with improvements in product quality and/or reduction in production costs. In the presence of suitable initiators, polymerisation of epoxies occurs via cationic mechanism, thus restricting the choice of the resin system components to species which do not contain electron donor groups. The present investigation is aimed to identify suitable co-monomers to be formulated with an epoxy resin, resulting in different cure reaction kinetics and application properties of the cured resin. In particular, four different anhydride types, three dicarboxylic and one tetracarboxylic, have been formulated at the same weight ratio with a diglydilether of bisphenol F and a photo-initiator. Resin samples, irradiated at different integrated doses, have been characterised with solubility tests, dynamic-mechanical thermal analysis and three point flexural tests, showing a response which is strongly affected by the specific chemical structure of the anhydride co-monomer. Post-irradiation thermal treatments carried out on samples irradiated at the lower dose suggest different reaction patterns, with different controlling factors depending on the activation mechanism (temperature or γ-rays).

  1. Preparation and Insulation Properties of Epoxy-Layered Silicate Nanocomposite

    NASA Astrophysics Data System (ADS)

    Imai, Takahiro; Sawa, Fumio; Ozaki, Tamon; Nakano, Toshiyuki; Shimizu, Toshio; Yoshimitsu, Tetsuo

    Recent rapid progress in nanotechnology has focused research and development efforts on new high performance materials. Organic-inorganic hybrid materials such as nylon-layered silicate nanocomposites have attracted special interest and various studies continue to be conducted on thermoplastic resins. In this study, we found out the best organic modifier of layered silicate that contributed to an affinity for epoxy resin (thermosetting resin), and succeeded in creating an intercalated-type epoxy-layered silicate nanocomposite. This nanocomposite realized some improvements by the addition of 5 or 6 weight percentage of organically modified layered silicates, which have 20oC higher thermal resistance, 60% higher fracture toughness, 19% higher flexural strength and 10% higher insulation breakdown strength than these of an epoxy resin without layered silicate fillers. An electrical treeing growth was observed in the nanocomposite. The electrical treeing progress with many branches in the nanocomposite seemed to result in an increase in the insulation breakdown strength. These results suggest the possibility of practical use as an insulating material in heavy apparatuses.

  2. Mechanical Properties of Triaxial Braided Carbon/Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Bowman, C. L.; Roberts, G. D.; Braley, M. S.; Xie, M.; Booker, M. J.

    2003-01-01

    In an on-going effort to increase the safety and efficiency of turbine engines, the National Aeronautics and Space Administration is exploring lightweight alternatives to the metal containment structures that currently encase commercial jet engines. Epoxy reinforced with braided carbon fibers is a candidate structural material which may be suitable for an engine case. This paper reports flat-coupon mechanical-property experiments performed to compliment previously reported subcomponent impact testing and analytical simulation of containment structures. Triaxial-braid T700/5208 epoxy and triaxial-braid T700/M36 toughened epoxy composites were evaluated. Also, two triaxial-braid architectures (0 +/- 60 deg., 0 +/- 45 deg.) with the M36 resin were evaluated through tension, compression, and shear testing. Tensile behavior was compared between standard straight-sided specimens (ASTM D3039) and bowtie specimens. Both double-notch shear (ASTM D3846) and Iosepescu (ASTM D5379) tests were performed as well. The M36/0 +/- 45 deg. configuration yield the best response when measurements were made parallel to the axial tows. Conversely, the M36/0 +/- 60 deg. configuration was best when measurements were made perpendicular to the axial tows. The results were used to identify critical properties and to augment the analysis of impact experiments.

  3. Durability of Intercalated Graphite Epoxy Composites in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Davidson, Michelle L.; Shively, Rhonda

    1996-01-01

    The electrical conductivity of graphite epoxy composites can be substantially increased by intercalating (inserting guest atoms or molecules between the graphene planes) the graphite fibers before composite formation. The resulting high strength, low density, electrically conducting composites have been proposed for EMI shielding in spacecraft. Questions have been raised, however, about their durability in the space environment, especially with respect to outgassing of the intercalates, which are corrosive species such as bromine. To answer those concerns, six samples of bromine intercalated graphite epoxy composites were included in the third Evaluation of Oxygen Interaction with Materials (EOIM-3) experiment flown on the Space Shuttle Discovery (STS-46). Changes in electrical conductivity, optical reflectance, surface texture, and mass loss for SiO2 protected and unprotected samples were measured after being exposed to the LEO environment for 42 hours. SiO2 protected samples showed no degradation, verifying conventional protection strategies are applicable to bromine intercalated composites. The unprotected samples showed that bromine intercalation does not alter the degradation of graphite-epoxy composites. No bromine was detected to have been released by the fibers allaying fears that outgassing could be disruptive to the sensitive electronics the EMI shield is meant to protect.

  4. Structural properties of laminated Douglas fir/epoxy composite material

    SciTech Connect

    Spera, D.A. . Lewis Research Center); Esgar, J.B. ); Gougeon, M.; Zuteck, M.D. )

    1990-05-01

    This publication contains a compilation of static and fatigue and strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 in. by 24 in. in cross section and approximately 30 ft long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications. 9 refs.

  5. Structural properties of laminated Douglas fir/epoxy composite material

    NASA Technical Reports Server (NTRS)

    Spera, David A.; Esgar, Jack B.; Gougeon, Meade; Zuteck, Michael D.

    1990-01-01

    This publication contains a compilation of static and fatigue strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 by 24 in. in cross section and approximately 30 ft. long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications.

  6. Epoxy-bonded La-Fe-Co-Si magnetocaloric plates

    NASA Astrophysics Data System (ADS)

    Pulko, Barbara; Tušek, Jaka; Moore, James D.; Weise, Bruno; Skokov, Konstantin; Mityashkin, Oleg; Kitanovski, Andrej; Favero, Chiara; Fajfar, Peter; Gutfleisch, Oliver; Waske, Anja; Poredoš, Alojz

    2015-02-01

    We report the processing, analysis and testing of magnetocaloric composite materials consisting of La-Fe-Co-Si particles of various size fractions and a polymer matrix. All of the composites have working temperatures close to room temperature. The composites were pressed into thin plates, a geometry favorable for testing the composites in an active magnetic regenerator (AMR). In order to investigate the influence of particle size and binder type (epoxy), eight different epoxy-bonded La-Fe-Co-Si plates were made and analyzed. We found that the higher filling factor that can be achieved by using a mixture of several particle size fractions has beneficial influence on the thermal conductivity. Tests in the AMR revealed that a maximum temperature span of approximately ΔT=10 K under magnetic field change of μ0H=1.15 T can be obtained at no cooling load conditions. The stability of the measured ΔT values and the mechanical integrity of sample after cyclic application of a magnetic field have been monitored for 90,000 cycles and showed no significant changes. We therefore conclude that epoxy-bonded La-Fe-Co-Si magnetocaloric composites have good magnetocaloric properties at low material-processing costs and hence represent a competitive way to produce magnetocaloric materials to be used in AMR.

  7. Latent Hardeners for the Assembly of Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Palmieri, Frank; Wohl, Christopher J.; Connell, John W.; Mercado, Zoar; Galloway, Jordan

    2016-01-01

    Large-scale composite structures are commonly joined by secondary bonding of molded-and-cured thermoset components. This approach may result in unpredictable joint strengths. In contrast, assemblies made by co-curing, although limited in size by the mold, result in stable structures, and are certifiable for commercial aviation because of structural continuity through the joints. Multifunctional epoxy resins were prepared that should produce fully-cured subcomponents with uncured joining surfaces, enabling them to be assembled by co-curing in a subsequent out-of-autoclave process. Aromatic diamines were protected by condensation with a ketone or aldehyde to form imines. Properties of the amine-cured epoxy were compared with those of commercially available thermosetting epoxy resins and rheology and thermal analysis were used to demonstrate the efficacy of imine protection. Optimum conditions to reverse the protecting chemistry in the solid state using moisture and acid catalysis were determined. Alternative chemistries were also investigated. For example, chain reaction depolymerization and photoinitiated catalysts would be expected to minimize liberation of volatile organic content upon deprotection and avoid residual reactive species that could damage the resin. Results from the analysis of protected and deprotected resins will be presented.

  8. Comparison of micromechanical models for elastic properties. [for unidirectional graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Lissenden, Cliff J.; Herakovich, Carl T.

    1992-01-01

    Results for the predicted effective elastic properties of unidirectional composites are presented for glass/epoxy and graphite/epoxy using eight different models. A brief review of each of the models is given along with the final equations in most cases. It is shown that there is wide variation in some predictions for glass/epoxy and that the upper and lower composite cylinder assemblage bounds do not always fall close together for this material.

  9. Processing of Clay/Epoxy Nanocomposites with a Three-Roll Mill Machine

    DTIC Science & Technology

    2003-01-01

    diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured with methyl tetrahydrophthalic anhydride hardener from Vantico was used as the matrix. 1...temperature and curing agent [4]. The commonly used techniques to process clay- epoxy nanocomposites are: direct mixing and solution mixing [4-71...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP014247 TITLE: Processing of Clay/ Epoxy Nanocomposites with a Three-Roll

  10. Modeling Strategy for Networks with Both Stepwise and Chainwise Mechanisms: Amine-Epoxy Chemistry with Etherification

    DTIC Science & Technology

    1989-05-01

    epoxides and carboxylic acids , isocyanates and alcohols, isocyanates and amines. 3 - CHEMISTRY Any model for network growth is only as good as the...is the initial recipe ratio, that is, the number of amino groups to the epoxy groups in the initial recipe. Ma and Me are the molecular weights of...where networks are produced under either of the above mentioned conditions. There is a commercial epoxy resin using an excess of epoxies ( DGEBA ) with a

  11. Investigation of the effect of resin material on impact damage to graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Palmer, R. J.

    1981-01-01

    The results of an experimental program are described which establishes the feasibility and guide lines for resin development. The objective was to identify the basic epoxy neat resin properties that improve low velocity impact resistance and toughness to graphite-epoxy laminates and at the same time maintain useful structural laminate mechanical properties. Materials tests from twenty-three toughened epoxy resin matrix systems are included.

  12. Polybenzimidazole compounds

    DOEpatents

    Klaehn, John R [Idaho Falls, ID; Peterson, Eric S [Idaho Falls, ID; Orme, Christopher J [Shelley, ID; Jones, Michael G [Chubbuck, ID; Wertsching, Alan K [Idaho Falls, ID; Luther, Thomas A [Idaho Falls, ID; Trowbridge, Tammy L [Idaho Falls, ID

    2011-11-22

    A PBI compound includes imidazole nitrogens at least a portion of which are substituted with a moiety containing a carbonyl group, the substituted imidazole nitrogens being bonded to carbon of the carbonyl group. At least 85% of the nitrogens may be substituted. The carbonyl-containing moiety may include RCO--, where R is alkoxy or haloalkyl. The PBI compound may exhibit a first temperature marking an onset of weight loss corresponding to reversion of the substituted PBI that is less than a second temperature marking an onset of decomposition of an otherwise identical PBI compound without the substituted moiety. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may use more than 5 equivalents in relation to the imidazole nitrogens to be substituted.

  13. Polybenzimidazole compounds

    DOEpatents

    Klaehn, John R.; Peterson, Eric S.; Wertsching, Alan K.; Orme, Christopher J.; Luther, Thomas A.; Jones, Michael G.

    2010-08-10

    A PBI compound that includes imidazole nitrogens, at least a portion of which are substituted with an organic-inorganic hybrid moiety. At least 85% of the imidazole nitrogens may be substituted. The organic-inorganic hybrid moiety may be an organosilane moiety, for example, (R)Me.sub.2SiCH.sub.2--, where R is selected from among methyl, phenyl, vinyl, and allyl. The PBI compound may exhibit similar thermal properties in comparison to the unsubstituted PBI. The PBI compound may exhibit a solubility in an organic solvent greater than the solubility of the unsubstituted PBI. The PBI compound may be included in separatory media. A substituted PBI synthesis method may include providing a parent PBI in a less than 5 wt % solvent solution. Substituting may occur at about room temperature and/or at about atmospheric pressure. Substituting may use at least five equivalents in relation to the imidazole nitrogens to be substituted or, preferably, about fifteen equivalents.

  14. Effects of colloidal nanosilica on the rheological properties of epoxy resins filled with organoclay.

    PubMed

    Nguyen, Dinh Huong; Song, Gwang Seok; Lee, Dai Soo

    2011-05-01

    The rheological properties of epoxy resins filled with organoclay and colloidal nanosilica were investigated by employing a parallel plate rheometer in flow mode at 25 degrees C. Shear thickening and shear thinning behaviors were observed in the epoxy resins filled with a mixture of organoclay and colloidal nanosilica. Minima were observed in the relaxation time of the systems consisting of epoxy resins filled with organoclay and colloidal silica as the content of colloidal nanosilica was increased. It seems that the colloidal nanosilica increased the mobility of the filled epoxy resins and reduced the interactions between the silicate layers in the systems.

  15. Structure within thin epoxy films revealed by solvent swelling: A neutron reflectivity study

    SciTech Connect

    KENT,MICHAEL S.; YIM,HYUN; MCNAMARA,WILLIAM FRERE; IVKOV,R.; SATIJA,S.; MAJEWSKI,J.

    2000-03-02

    The focus of this work is the structure within highly crosslinked, two component epoxy films. The authors examine variations in crosslink density within thin epoxy films on silicon substrates by solvent swelling. The method is based on the fact that the equilibrium volume fraction of a swelling solvent is strongly dependent upon the local crosslink density. The authors examine the volume fraction profile of the good solvent nitrobenzene through the epoxy films by neutron reflection. Isotopic substitution is used to provide contrast between the epoxy matrix and the swelling solvent.

  16. Studies on adhesion characteristics and corrosion behaviour of vinyltriethoxysilane/epoxy coating protective system on aluminium

    NASA Astrophysics Data System (ADS)

    Bajat, Jelena B.; Milošev, Ingrid; Jovanović, Željka; Mišković-Stanković, Vesna B.

    2010-03-01

    The corrosion stability of vinyltriethoxysilane/epoxy coating protective system on aluminium is strongly related to the strength of bonds forming at the metal/organic coating interface. This article is a study of adhesion, composition, electrochemical and transport properties of epoxy coatings electrodeposited on bare aluminium and aluminium pretreated by vinyltriethoxysilane (VTES) during exposure to 3% NaCl. The VTES film was deposited on aluminium surface from 2% vinyltriethoxysilane solution during 30 s. From the values of adhesion strength (pull-off test), time dependence of pore resistance and coating capacitance of epoxy coating (impedance measurements) and diffusion coefficient of water through epoxy coating (gravimetric liquid sorption measurements), the influence of VTES sublayer on the corrosion stability of the electrodeposited epoxy coating was shown. The work discusses the role of the VTES pretreatment in the enhanced adhesion and corrosion stability of epoxy cataphoretic coating. The electrochemical results showed that the aluminium pretreatment by VTES film improved barrier properties of epoxy coating (greater pore resistance and lower coating capacitance). The lower value of diffusion coefficient of water through epoxy coating indicates the lower porosity, while the smaller adhesion reduction points to better adhesion of epoxy coating on aluminium pretreated by VTES film. The composition of the deposited coatings investigated by XPS enabled the clarification of the bonding mechanism.

  17. Corrosion behavior of modified nano carbon black/epoxy coating in accelerated conditions

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    The electrochemical behavior and anticorrosion properties of modified carbon black (CB) nanoparticles in epoxy coatings were investigated in accelerated conditions. Nanoparticles of CB were modified by sodium dodecyl sulfate (SDS) as surfactant. Dispersion of nanoparticles into epoxy was confirmed by Transmission Electron Microscopy (TEM). The accelerated condition was prepared at 65 °C. CB nanoparticles improved corrosion resistance of the epoxy coating. The optimum concentration of CB in the epoxy coating was 0.75 wt%. Results showed that the CB hinder the corrosion due to its barrier properties. CB can decrease the diffusion coefficient of water in the coating with filling the micropores.

  18. A new triterpenoid compound from stems and leaves of American ginseng.

    PubMed

    Han, Liu; Li, Zhuo; Zheng, Qian; Liu, Jin-Ping; Li, Ping-Ya

    2016-01-01

    A new dammarane-type triterpenoid compound was isolated from stems and leaves of American ginseng. The structure of the new sapogenin was elucidated by the combined analysis of NMR and HR-ESI-MS as dammar-20S, 25S-epoxy-3β, 12β, 26-triol (1). Compound 1 showed cytotoxic effect on human SM7721 and human Hela cells in vitro.

  19. New Insights of Comets from the EPOXI Mission

    NASA Astrophysics Data System (ADS)

    Meech, Karen J.; A'Hearn, M. F.

    2013-01-01

    Comet missions are changing the paradigm for understanding comet activity, composition, and the formation of planetesimals in the protoplanetary disk. Each encounter has shown the diversity of surface morphologies and new insights into comet chemistry, formation scenarios, activity mechanisms and geology. Prior to the comet 103P/Hartley 2 EPOXI encounter, the prevailing view was that H 2O-ice sublimation controlled most comet activity. Differences in the amounts of minor parent/daughter photodissociation species are attributed to differences in formation location, temperature and disk chemistry. However, reconstructing the protoplanetary disk dynamics and chemistry consistent with observations hasn’t yet been achieved. The EPOXI mission flew past the nucleus of comet 103P/Hartley 2 on 11/4/2010. This small nucleus was known to be exceptionally active prior to the encounter, by virtue of a very large water production rate relative to its surface area. EPOXI provided stunning images of a small nucleus with strong chemical heterogeneity and a swarm of large icy chunks driven from the nucleus by CO2 jets. The EPOXI ground-based campaign provided a long-term baseline of observations of the pre-perihelion brightening of the comet which also showed that comet Hartley 2’s perihelion activity was dominated by sub-surface CO2 outgassing. The nucleus morphology was different from that of other nuclei visited by spacecraft; some rough topographic regions showed visible surface ice. Because the Earth’s atmosphere is opaque at the wavelengths for CO2 emission, there is only a little information about CO2 abundance in comets (primarily from space missions), yet CO, CO2 and H2O are likely key tracers of the chemistry in the protoplanetary disk. EPOXI has shown the crucial role that CO2 plays in comet activity. Further, CO2 abundance does not appear to be correlated with other parent volatiles, nor with dynamical classes suggesting that we need to revise our understanding of

  20. Epoxy and Silicone Optical Nanocomposites Filled with Grafted Nanoparticles

    NASA Astrophysics Data System (ADS)

    Tao, Peng

    Polymer nanocomposites, as a technologically important class of materials, exhibit diverse functional properties, and are used for applications ranging from structural and biomedical to electronic and optical. The properties of polymer nanocomposites are determined, in part, by the chemical composition of the polymer matrix and the nanofillers. Their properties are also sensitive to the geometry and size of the nanofillers, and to spatial distribution of the fillers. Control of the nanoparticle size and dispersion within a given polymer provides opportunities to tailor and optimize the properties of nanocomposites for specific application. For optical applications such as encapsulation of light emitting diodes (LEDs), polymer nanocomposites filled with homogeneously dispersed nanoparticles would endow the polymer encapsulant with new functionality without sacrificing optical transparency. To this end, this thesis focuses on developing a simple and versatile approach towards the fabrication of epoxy and silicone transparent nanocomposites using matrix compatible chain-grafted nanoparticles as fillers, and studying the optical properties of the nanocomposites. The surface chemistry and grafted polymer chain design have been shown to play an important role in determining the dispersion state of the grafted nanoparticles and hence the final optical properties of the nanocomposites. To prepare transparent epoxy nanocomposites, poly (glycidyl methacrylate) (PGMA) chains were grafted onto the optical nanoparticle surfaces via a combined phosphate ligand exchange process and azide-alkyne "click" chemistry. The dispersion behavior of PGMA-grafted nanoparticles within the epoxy matrix was investigated by systematically varying the grafting density and grafted chain length. It was found that within the small molecular weight epoxy resins, the dispersion states are more sensitive to the grafting density than the molecular weight of grafted chains. With high grafting densities

  1. Rodent Biocompatibility Test Using the NASA Foodbar and Epoxy EP21LV

    NASA Technical Reports Server (NTRS)

    Tillman, J.; Steele, M.; Dumars, P.; Vasques, M.; Girten, B.; Sun, S. (Technical Monitor)

    2002-01-01

    Epoxy has been used successfully to affix NASA foodbars to the inner walls of the Animal Enclosure Module for past space flight experiments utilizing rodents. The epoxy used on past missions was discontinued, making it necessary to identify a new epoxy for use on the STS-108 and STS-107 missions. This experiment was designed to test the basic biocompatibility of epoxy EP21LV with male rats (Sprague Dawley) and mice (Swiss Webster) when applied to NASA foodbars. For each species, the test was conducted with a control group fed untreated foodbars and an experimental group fed foodbars applied with EP21LV. For each species, there were no group differences in animal health and no statistical differences (P<0.05) in body weights throughout the study. In mice, there was a 16% increase in heart weight in the epoxy group; this result was not found in rats. For both species, there were no statistical differences found in other organ weights measured. In rats, blood glucose levels were 15% higher and both total protein and globulin were 10% lower in the epoxy group. Statistical differences in these parameters were not found in mice. For both species, no statistical differences were found in other blood parameters tested. Food consumption was not different in rats but water consumption was significantly decreased 10 to 15% in the epoxy group. The difference in water consumption is likely due to an increased water content of the epoxy-treated foodbars. Finally, both species avoided consumption of the epoxy material. Based on the global analysis of the results, the few parameters found to be statistically different do not appear to be a physiologically relevant effect of the epoxy material, We conclude that the EP21LV epoxy is biocompatible with rodents.

  2. Behaviour of hybrid jute-glass/epoxy composite tubes subjected to lateral loading

    NASA Astrophysics Data System (ADS)

    Khalid, A. A.

    2015-12-01

    Experimental work on hybrid and non-hybrid composite tubes subjected to lateral loading has been carried out using jute, glass and hybrid jute-glass/epoxy materials. Tubes of 200 mm length with 110 mm inner diameter were fabricated by hand lay-up method to investigate the effect of material used and the number of layers on lateral-load-displacement relations and on the failure mode. Crush force efficiency and the specific energy absorption of the composite tubes were calculated. Results show that the six layers glass/epoxy tubes supported load higher 10.6% than that of hybrid jute-glass/ epoxy made of two layers of jute/epoxy four layers of glass/epoxy. It has been found that the specific energy absorption of the glass/epoxy tubes is found higher respectively 11.6% and 46% than hybrid jute-glass/epoxy and jute/epoxy tubes. The increase in the number of layers from two to six increases the maximum lateral load from 0.53KN to 1.22 KN for jute/epoxy and from 1.35 KN to 3.87 KN for the glass/epoxy tubes. The stacking sequence of the hybrid tubes influenced on the maximum lateral load and the absorbed energy. The maximum load obtained for the six layers jute-glass/epoxy tubes of different staking sequence varies between 1.88 KN to 3.46 KN. Failure mechanisms of the laterally loaded composite tubes were also observed and discussed.

  3. Determination of Young's modulus of epoxy coated polyethylene micro-cantilever using phase-shift shadow moiré method

    NASA Astrophysics Data System (ADS)

    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.

  4. Multipurpose Compound

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Specially formulated derivatives of an unusual basic compound known as Alcide may be the answer to effective treatment and prevention of the disease bovine mastitis, a bacterial inflammation of a cow's mammary gland that results in loss of milk production and in extreme cases, death. Manufactured by Alcide Corporation the Alcide compound has killed all tested bacteria, virus and fungi, shortly after contact, with minimal toxic effects on humans or animals. Alcide Corporation credits the existence of the mastitis treatment/prevention products to assistance provided the company by NERAC, Inc.

  5. Drop Reliability of Epoxy-contained Sn-58 wt.%Bi Solder Joint with ENIG and ENEPIG Surface Finish Under Temperature and Humidity Test

    NASA Astrophysics Data System (ADS)

    Myung, Woo-Ram; Kim, Yongil; Kim, Kyung-Yeol; Jung, Seung-Boo

    2016-07-01

    The influence of two kinds of surface finish, namely electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG), on the interfacial reactions and drop reliability of epoxy-enhanced Sn-58 wt.%Bi solder has been investigated after temperature-humidity storage tests. The chemical composition and morphology of intermetallic compounds (IMCs) were characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy, and electron probe microanalysis. Also, the mechanical reliability of solder joints was evaluated using board-level drop tests. The Sn-Bi epoxy solder/ENEPIG joint exhibited higher IMC growth rate than the Sn-Bi epoxy solder/ENIG joint. After 500 h at 85°C/85% RH storage condition, new IMCs were formed on the Ni3Sn4 layer in samples with both surface finishes. The results of board-level drop tests showed that the number of drops was higher for the ENIG than the ENEPIG surface finish. Solder joint fracture occurred along the interface between the solder and IMC layer for the ENIG surface finish. However, with the ENEPIG surface finish, the crack propagated between the IMCs.

  6. Highly Conducting Graphite Epoxy Composite Demonstrated

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1999-01-01

    Weight savings as high as 80 percent could be achieved if graphite polymer composites could replace aluminum in structures such as electromagnetic interference shielding covers and grounding planes. This could result in significant cost savings, especially for the mobile electronics found in spacecraft, aircraft, automobiles, and hand-held consumer electronics. However, such composites had not yet been fabricated with conductivity sufficient to enable these applications. To address this lack, a partnership of the NASA Lewis Research Center, Manchester College, and Applied Sciences, Inc., fabricated nonmetallic composites with unprecedented electrical conductivity. For these composites, heat-treated, vapor-grown graphite fibers were selected which have a resistivity of about 80 mW-cm, more than 20 times more conductive than typical carbon fibers. These fibers were then intercalated with iodine bromide (IBr). Intercalation is the insertion of guest atoms or molecules between the carbon planes of the graphite fibers. Since the carbon planes are not highly distorted in the process, intercalation has little effect on mechanical and thermal properties. Intercalation does, however, lower the carbon fiber resistivity to less than 10 mW-cm, which is comparable to that of metal fibers. Scaleup of the reaction was required since the initial intercalation experiments would be carried out on 20-mg quantities of fibers, and tens of grams of intercalated fibers would be needed to fabricate even small demonstration composites. The reaction was first optimized through a time and temperature study that yielded fibers with a resistivity of 8.7 2 mW-cm when exposed to IBr vapor at 114 C for 24 hours. Stability studies indicated that the intercalated fibers rapidly lost their conductivity when exposed to temperatures as low as 40 C in air. They were not, however, susceptible to degradation by water vapor in the manner of most graphite intercalation compounds. The 1000-fold scaleup

  7. Perfluorinated Compounds

    EPA Science Inventory

    Perfluorinated compounds such as the perfluoroalkyl acids (PFAAs) and their derivatives are important man-made chemicals that have wide consumer and industrial applications. They are relatively contemporary chemicals, being in use only since the 1950s, and until recently, have be...

  8. Synthesis and properties of transparent cycloaliphatic epoxy-silicone resins for opto-electronic devices packaging

    NASA Astrophysics Data System (ADS)

    Gao, Nan; Liu, WeiQu; Yan, ZhenLong; Wang, ZhengFang

    2013-01-01

    Cycloaliphatic epoxy-silicone resins were successfully synthesized through a two-step reaction route: (і) hydrosilylation of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) and 1,2-epoxy-4-vinyl-cyclohexane (VCMX), (іі) blocking of unreacted Sisbnd H in (і) with n-butanol. The molecular structures of the cycloaliphatic epoxy-silicone resins were characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H NMR and 29Si NMR). High grafting efficiencies of epoxy groups were confirmed by 1H NMR combined with weighting results, indicating over 90 mol% of cycloaliphatic epoxy were grafted on the silicone resins. Subsequently, Sisbnd H groups from TMCTS were almost totally consumed after the blocking reactions. In comparison with commercial available cycloaliphatic epoxy resin 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ERL-4221) cured by MHHPA, the cured cycloaliphatic epoxy-silicone resins exhibited better thermal stability, lower water absorption and higher UV/thermal resistance. Moreover, the characteristics of transmittance (>90%, 800 nm), 5 wt.% mass loss temperature (>330 °C) and no yellowing during thermal aging at 120 °C or UV aging for 288 h of the cured cycloaliphatic epoxy-silicone resins, made them possible for power light-emitting diode (LED) encapsulants, or other packaging materials, like optical lenses, and electronic sealings.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Equation of State of Aluminum-Iron Oxide-Epoxy Composite

    DTIC Science & Technology

    2007-07-01

    We report on the measurements of the shock equation of state (Hugoniot) of an Al/Fe2O3/epoxy composite, prepared by epoxy cast curing of powder...corresponding shock propagation velocity. The results of the Hugoniot equation of state are compared with mesoscale finite-element simulations, which show good agreement.

  11. Shock Equation of State of Single Constituent and Multi-Constituent Epoxy-Based Particulate Composites

    DTIC Science & Technology

    2010-10-01

    There are several studies in the literature regarding the equation of state of alumina-epoxy composites. Although this single component system...paper presents a review of shock loading studies on epoxy-based particulate composites. The relationship between equation of state parameters and

  12. High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators

    DOEpatents

    Janke, Christopher J.; Lopata, Vincent J.; Havens, Stephen J.; Dorsey, George F.; Moulton, Richard J.

    1999-01-01

    A mixture of epoxy resins such as a semi-solid triglycidyl ether of tris (hydroxyphenyl) methane and a low viscosity bisphenol A glycidyl ether and a cationic photoinitiator such as a diaryliodonium salt is cured by irradiating with a dosage of electron beams from about 50 to about 150 kGy, forming a cross-linked epoxy resin polymer.

  13. High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators

    DOEpatents

    Janke, C.J.; Lopata, V.J.; Havens, S.J.; Dorsey, G.F.; Moulton, R.J.

    1999-03-02

    A mixture of epoxy resins such as a semi-solid triglycidyl ether of tris (hydroxyphenyl) methane and a low viscosity bisphenol A glycidyl ether and a cationic photoinitiator such as a diaryliodonium salt is cured by irradiating with a dosage of electron beams from about 50 to about 150 kGy, forming a cross-linked epoxy resin polymer.

  14. Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites

    PubMed Central

    Hamim, Salah U.; Singh, Raman P.

    2014-01-01

    Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface. PMID:27379285

  15. 78 FR 4792 - Epoxy Polymer; Exemption From the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-23

    ... AGENCY 40 CFR Part 180 Epoxy Polymer; Exemption From the Requirement of a Tolerance AGENCY: Environmental... requirement of a tolerance for residues of polymers of one or more diglycidyl ethers of bisphenol A...- cyclohexane-dicarboxylic anhydride and 1,2,3,6-tetrahydrophthalic anhydride; also referred to as epoxy...

  16. Preparation, characterization, and enhanced thermal and mechanical properties of epoxy-titania composites.

    PubMed

    Rubab, Zakya; Afzal, Adeel; Siddiqi, Humaira M; Saeed, Shaukat

    2014-01-01

    This paper presents the synthesis and thermal and mechanical properties of epoxy-titania composites. First, submicron titania particles are prepared via surfactant-free sol-gel method using TiCl₄ as precursor. These particles are subsequently used as inorganic fillers (or reinforcement) for thermally cured epoxy polymers. Epoxy-titania composites are prepared via mechanical mixing of titania particles with liquid epoxy resin and subsequently curing the mixture with an aliphatic diamine. The amount of titania particles integrated into epoxy matrix is varied between 2.5 and 10.0 wt.% to investigate the effect of sub-micron titania particles on thermal and mechanical properties of epoxy-titania composites. These composites are characterized by X-ray photoelectron (XPS) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric (TG), and mechanical analyses. It is found that sub-micron titania particles significantly enhance the glass transition temperature (>6.7%), thermal oxidative stability (>12.0%), tensile strength (>21.8%), and Young's modulus (>16.8%) of epoxy polymers. Epoxy-titania composites with 5.0 wt.% sub-micron titania particles perform best at elevated temperatures as well as under high stress.

  17. Effect of Geopolymer filler in Glass Reinforced Epoxy (GRE) Pipe for Piping Application: Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Firdaus Abu Hashim, Mohammad; Bakri Abdullah, Mohd Mustafa Al; Mohd Ruzaidi Ghazali, Che; Hussin, Kamarudin; Binhussain, Mohammed

    2016-06-01

    The present work is aimed to carry out the effect of geopolymer material which is fly ash as filler in the glass reinforced epoxy pipe on the micro structure of fly ash geopolymer, compression properties, and bulk density using the filament winding method. Conventional glass reinforced epoxy pipes has its own disadvantages such as high corrosion resistance at acidic environment and low strength which can be replaced by the composite pipes. Geopolymer is a type of amorphous alumino-silicate and can be synthesized by geopolymerization process. A series of glass reinforced epoxy pipe and glass reinforced epoxy pipe filled with 10 - 40 weight percentage geopolymer filler which is fly ash with 4 Molarity were prepared. Morphology of the raw material fly ash and fly ash based-geopolymer surface was characterized using scanning electron microscopy. It was found that the additions of fly ash at the beginning with 10 wt% are showing higher compressive strength than glass reinforced epoxy pipe without fly ash geopolymer filler. The compressive test of these series of samples was determined using Instron Universal Testing under compression mode. It was found that compressive strength for samples fly ash based-geopolymer filler are higher as compared to glass reinforced epoxy pipe without geopolymer filler. However, the compressive strength of glass reinforced epoxy pipe with fly ash geopolymer filler continues to decline when added to 20 wt% - 40 wt% of geopolymer filler loading. The results showed that the mixing of geopolymer materials in epoxy system can be obtained in this study.

  18. 40 CFR 180.1283 - (Z)-7,8-epoxy-2-methyloctadecane (Disparlure); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false (Z)-7,8-epoxy-2-methyloctadecane... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1283 (Z)-7,8-epoxy-2-methyloctadecane... is established for residues of (Z)-7,8-epoxy-2-methyloctadecane on all food and feed crops that...

  19. 40 CFR 721.10209 - Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Epoxy terminated, hydrolyzed... Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin (generic... identified generically as epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of...

  20. 40 CFR 180.1283 - (Z)-7,8-epoxy-2-methyloctadecane (Disparlure); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false (Z)-7,8-epoxy-2-methyloctadecane... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1283 (Z)-7,8-epoxy-2-methyloctadecane... is established for residues of (Z)-7,8-epoxy-2-methyloctadecane on all food and feed crops that...

  1. 40 CFR 180.1283 - (Z)-7,8-epoxy-2-methyloctadecane (Disparlure); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false (Z)-7,8-epoxy-2-methyloctadecane... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1283 (Z)-7,8-epoxy-2-methyloctadecane... is established for residues of (Z)-7,8-epoxy-2-methyloctadecane on all food and feed crops that...

  2. 21 CFR 177.2280 - 4,4′-Isopropyl-idenedi-phenol-epichloro-hydrin thermo-setting epoxy resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... thermo-setting epoxy resins. 177.2280 Section 177.2280 Food and Drugs FOOD AND DRUG ADMINISTRATION...,4′-Isopropyl-idenedi-phenol-epichloro-hydrin thermo-setting epoxy resins. 4,4′-Isopropylidenediphenol-epichlo-rohydrin thermosetting epoxy resins may be safely used as articles or components...

  3. 21 CFR 177.2280 - 4,4′-Isopropyl-idenedi-phenol-epichloro-hydrin thermo-setting epoxy resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... thermo-setting epoxy resins. 177.2280 Section 177.2280 Food and Drugs FOOD AND DRUG ADMINISTRATION...-epichloro-hydrin thermo-setting epoxy resins. 4,4′-Isopropylidenediphenol-epichlo-rohydrin thermosetting epoxy resins may be safely used as articles or components of articles intended for repeated use...

  4. 40 CFR 721.10209 - Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Epoxy terminated, hydrolyzed... Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin (generic... identified generically as epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of...

  5. 40 CFR 721.10209 - Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Epoxy terminated, hydrolyzed... Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin (generic... identified generically as epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of...

  6. 21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant...

  7. 21 CFR 177.2280 - 4,4′-Isopropyl-idenedi-phenol-epichloro-hydrin thermo-setting epoxy resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... thermo-setting epoxy resins. 177.2280 Section 177.2280 Food and Drugs FOOD AND DRUG ADMINISTRATION...,4′-Isopropyl-idenedi-phenol-epichloro-hydrin thermo-setting epoxy resins. 4,4′-Isopropylidenediphenol-epichlo-rohydrin thermosetting epoxy resins may be safely used as articles or components...

  8. 40 CFR 180.1283 - (Z)-7,8-epoxy-2-methyloctadecane (Disparlure); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false (Z)-7,8-epoxy-2-methyloctadecane... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1283 (Z)-7,8-epoxy-2-methyloctadecane... is established for residues of (Z)-7,8-epoxy-2-methyloctadecane on all food and feed crops that...

  9. 40 CFR 180.1283 - (Z)-7,8-epoxy-2-methyloctadecane (Disparlure); exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false (Z)-7,8-epoxy-2-methyloctadecane... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1283 (Z)-7,8-epoxy-2-methyloctadecane... is established for residues of (Z)-7,8-epoxy-2-methyloctadecane on all food and feed crops that...

  10. 40 CFR 721.10209 - Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Epoxy terminated, hydrolyzed... Epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of phenol-formaldehyde resin (generic... identified generically as epoxy terminated, hydrolyzed trialkoxysilane and glycidyl ether of...

  11. 21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant...

  12. 21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant...

  13. Study of Graphite/Epoxy Composites for Material Flaw Criticality.

    DTIC Science & Technology

    1980-11-01

    midsurface (between plies 32 and 33) in each specimen. The two disbonds were placed symmetri- cally with respect to the center of the beam span. To...the midsurface of a (04/±45 /:T45 /04)sI graphite/epoxy laminate were calculated by the use of the methods presented. Elastic properties of the...the midsurface there is no extension-bending coupling and twisting-bending coupling is not too large. Therefore, the two (0/±45/T45/0) laminates can

  14. Corrosion Control at Graphite/Epoxy-Aluminum and Titanium Interfaces

    DTIC Science & Technology

    1974-07-01

    200000 ■ 30000 40000 * 1 From Graphlte/Epoxy To Faatener No. 5 ■ 60000 20000 1000000 ISO 160000 -o 20 1(1 50000 400 ISO 2(10 700000...so JO 40000 100000 II ■ 600 50000; 200000 ■ ic 50000 500000 100000 50000 50000 150000 80000 MO 26000 60000 40 500 170 100 cc 200 7 1 m m ■ ■ 40000...40000 50 " 200000 20 u w 60000 0.18 • • 250000 2(0000 260000 0.3 0. 007 26000 0.006 0.004 0.02 1000000 0.005 0.011 tow 200000 0.018 130000 2

  15. Wave propagation in graphite/epoxy laminates due to impact

    NASA Technical Reports Server (NTRS)

    Tan, T. M.; Sun, C. T.

    1982-01-01

    The low velocity impact response of graphite-epoxy laminates is investigated theoretically and experimentally. A nine-node isoparametric finite element in conjunction with an empirical contact law was used for the theoretical investigation. Flat laminates subjected to pendulum impact were used for the experimental investigation. Theoretical results are in good agreement with strain gage experimental data. The collective results of the investigation indicate that the theoretical procedure describes the impact response of the laminate up to about 150 in/sec. impact velocity.

  16. Silver-epoxy microwave filters and thermalizers for millikelvin experiments

    SciTech Connect

    Scheller, Christian P.; Heizmann, Sarah; Bedner, Kristine; Giss, Dominic; Zumbühl, Dominik M.; Meschke, Matthias; Zimmerman, Jeramy D.; Gossard, Arthur C.

    2014-05-26

    We present silver-epoxy filters combining excellent microwave attenuation with efficient wire thermalization, suitable for low temperature quantum transport experiments. Upon minimizing parasitic capacitances, the attenuation reaches ≥100 dB above ≈150 MHz and—when capacitors are added—already above ≈30 MHz. We measure the device electron temperature with a GaAs quantum dot and demonstrate excellent filter performance. Upon improving the sample holder and adding a second filtering stage, we obtain electron temperatures as low as 7.5 ± 0.2 mK in metallic Coulomb blockade thermometers.

  17. Comparative evaluation of woven graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Hanagud, S.; Tayebi, A.; Clinton, R. G., Jr.; Nayak, B. M.

    1979-01-01

    A comparative evaluation of some of the mechanical properties of woven graphite-epoxy composites are discussed. In particular, the types of weaves and the resin contents were chosen for comparison. The types of weaves selected are plain weave, satin weave, and tridirectional weave. The composites made of the fabrics are compared to composites made from unidirectional tapes under static and fatigue loading. During static loading, acoustic emission events were monitored. Also, examinations of fracture surfaces and polished sections both away from the fracture surface, and of virgin specimens under an electron microscope are discussed.

  18. The interlaminar fracture toughness of woven graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Funk, Joan G.; Deaton, Jerry W.

    1989-01-01

    The interlaminar fracture toughness of 2-D graphite/epoxy woven composites was determined as a function of stacking sequence, thickness, and weave pattern. Plain, oxford, 5-harness satin, and 8-harness satin weaves of T300/934 material were evaluated by the double cantilever beam test. The fabric material had a G (sub Ic) ranging from 2 to 8 times greater than 0 degrees unidirectional T300/934 tape material. The interlaminar fracture toughness of a particular weave style was dependent on whether the stacking sequence was symmetric or asymmetric and, in some cases, on the fabric orientation.

  19. Stability of some epoxy-encapsulated diode thermometers

    NASA Technical Reports Server (NTRS)

    Mangum, B. W.; Evans, G. A., Jr.

    1986-01-01

    The stability upon thermal cycling and handling of ten small, epoxy-encapsulated silicon diode thermometers at six temperatures in the range from liquid nitrogen temperatures to about 60 C. The nominal temperatures of measurement were -196, -78, 0, 20, 40, and 60 C, as measured on the International Practical Temperature Scale of 1968. Diodes were to be thermally cycled 15 to 20 times. Since NASA anticipates that the uncertainty in their temperature measurements will be + or - 50 mK, uncertainties as large as + or - 10 mK in the measurements of the evaluaton can be accommodated without deleteriously affecting the value of the results of the investigation.

  20. Space Radiation Effects on Graphite-Epoxy Composite Materials

    DTIC Science & Technology

    1984-06-01

    147 b.2 Degradation of the Epoxy Resin Due to Electron I rradiation ... ... 149 b.3 Analysis of Failure Surfaces...............-........ 150 VRI SUMMARY...Irradiated Shear Modulus, G1 2 , as a Function of Temp ercj tu re.... -.* .1 .* I * 90 41. Non-y/ rradiated Poisson’s Ratio, v 1 2 , as a Function ofT...1480F to 176 0 F -1480F to 1040F 173K to 353K 173K to 313K + Environment UV , e , p , VAC.,.AT UV , VAC., AT Electrical < 1-8 (ohm- 1cm-l) 10-8 10-17

  1. Comparative evaluation of woven graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Hanagud, S.; Tayebi, A.; Clinton, R. G.; Nayak, B. M.

    1979-01-01

    A comparative evaluation of some of the mechanical properties of woven graphite-epoxy composites have been discussed in this report. In particular the types of weaves and the resin contents have been chosen for comparison. The types of weaves selected are plain weaves, satin weave and tri-directional weave. The composites made of these fabrics have been compared to composites made from unidirectional tapes under static and fatigue loading. During static loading acoustic emission events have been monitored. Also, examinations of fracture surface and polished sections of specimens away from the fracture surface under an electron microscope have been discussed.

  2. Study of AC electrical conduction mechanisms in an epoxy polymer

    NASA Astrophysics Data System (ADS)

    Jilani, Wissal; Mzabi, Nissaf; Gallot-Lavallée, Olivier; Fourati, Najla; Zerrouki, Chouki; Zerrouki, Rachida; Guermazi, Hajer

    2015-11-01

    The AC conductivity of an epoxy resin was investigated in the frequency range 10^{-1} - 106 Hz at temperatures ranging from -100 to 120 °C. The frequency dependence of σ_{ac} was described by the law: σ_{ac}=ω \\varepsilon0\\varepsilon^''_{HN}+Aωs. The study of temperature variation of the exponent (s) reveals two conduction models: the AC conduction dependence upon temperature is governed by the small polaron tunneling mechanism (SPTM) at low temperature (-100 -60 °C) and the correlated barrier hopping (CHB) model at high temperature (80-120 °C).

  3. Impact behavior of graphite-epoxy simulated fan blades

    NASA Technical Reports Server (NTRS)

    Cook, T. S.; Preston, J. L., Jr.

    1977-01-01

    The response of a graphite-epoxy material, Modmor II/PR-286, to foreign object impact was investigated by impacting spherical projectiles of three different materials - gelatin, ice, and steel - on simulated blade specimens. Visual and metallographic inspection revealed three damage mechanisms: penetration, leading edge bending failure, and stress wave delamination and cracking. The steel projectiles caused penetration damage regardless of the impact location and angle. For the ice and gelatin particles impacting the leading edge, failure was due to large local bending strains, resulting in significant material removal and delamination damage.

  4. Visualization of impact damaging of carbon/epoxy panels

    NASA Astrophysics Data System (ADS)

    Boccardi, Simone; Boffa, Natalino Daniele; Carlomagno, Giovanni Maria; Meola, Carosena; Ricci, Fabrizio

    2016-05-01

    This work is concerned with impact damaging of carbon/epoxy materials. Specimens of different thickness are herein considered, which involve several fibers orientations and stacking sequences. Impact tests are carried out at different energies with a modified Charpy pendulum. The specimen surface opposite to that struck by the impactor is viewed by an infrared imaging device. Then, a sequence of thermal images is acquired during each impact test. Through the temperature variations experienced by the specimen surface, post-processing of such images supplies the likely occurred damage. In addition, specimens are non-destructively evaluated with lock-in thermography to visualize any manufacturing defects, as well as impact damage.

  5. New functionalized block copolymers for bonding copper to epoxy

    SciTech Connect

    Kent, M.; Saunders, R.; Emerson, J.; Hurst, M.

    1995-11-01

    The authors are exploring the use of functionalized block copolymers for bonding copper to epoxy in printed wiring boards. The program involves four key elements: (i) synthesis of suitable functionalized block copolymers; (ii) characterization of the conformation of the copolymers at the relevant interfaces by neutron reflectivity; (iii) spectroscopic measurements of chemical bonding, and (iv) measurement of the mechanical properties of the interfaces. The copolymers are synthesized by living, ring-opening metathesis polymerization. This relatively new technique allows great flexibility for synthesis of functionalized block copolymers in that the initiators are relatively insensitive to a wide range of functional groups. Significant adhesion enhancement has been observed in lap shear tests.

  6. Cryogenic compressive properties of basic epoxy resin systems

    SciTech Connect

    Markley, F.W.; Hoffman, J.A.; Muniz, D.P.

    1985-09-01

    The compressive properties of short cylindrical samples of many different epoxy resin systems have been measured at ambient temperature and at 77/sup 0/K. These are pure resin systems of known chemistry, without the inorganic fillers or fibrous reinforcements needed in final cryogenic systems. Of course, chemically incorporated modifiers such as flexibilizing resins have been included. This data should make possible inferences about cryogenic properties from molecular structures and provide specific data useful to formulators and end users. Measurements on some other plastics such as PTFE, Polyimides, and UHMWPE have been made for comparison purposes.

  7. Ultrasonic nondestructive evaluation of graphite epoxy composite laminates

    NASA Technical Reports Server (NTRS)

    Miller, James G.

    1990-01-01

    Quantitative ultrasonic techniques are summarized with applications to the measurement of frequency-dependent attenuation and backscatter and to the NDE of composite laminates. Results are listed for the ultrasonic NDE of graphite-epoxy composite laminates including impact and fatigue damage as well as porosity. The methods reviewed include transmission measurements of attenuation, reconstructive tomography based on attenuation, estimating attenuation from backscattered ultrasound, and backscatter approaches. Phase-sensitive and -insensitive detection techniques are mentioned such as phase cancellation at piezoelectric receiving transducers and acoustoelectric effects. The techniques permit the NDE of the parameters listed in inhomogeneous media and provide both images from the transmission mode and in the reflection mode.

  8. SREF - a Simple Removable Epoxy Foam decomposition chemistry model.

    SciTech Connect

    Hobbs, Michael L.

    2003-12-01

    A Simple Removable Epoxy Foam (SREF) decomposition chemistry model has been developed to predict the decomposition behavior of an epoxy foam encapsulant exposed to high temperatures. The foam is composed of an epoxy polymer, blowing agent, and surfactant. The model is based on a simple four-step mass loss model using distributed Arrhenius reaction rates. A single reaction was used to describe desorption of the blowing agent and surfactant (BAS). Three of the reactions were used to describe degradation of the polymer. The coordination number of the polymeric lattice was determined from the chemical structure of the polymer; and a lattice statistics model was used to describe the evolution of polymer fragments. The model lattice was composed of sites connected by octamethylcylotetrasiloxane (OS) bridges, mixed product (MP) bridges, and bisphenol-A (BPA) bridges. The mixed products were treated as a single species, but are likely composed of phenols, cresols, and furan-type products. Eleven species are considered in the SREF model - (1) BAS, (2) OS, (3) MP, (4) BPA, (5) 2-mers, (6) 3-mers, (7) 4-mers, (8) nonvolatile carbon residue, (9) nonvolatile OS residue, (10) L-mers, and (11) XL-mers. The first seven of these species (VLE species) can either be in the condensed-phase or gas-phase as determined by a vapor-liquid equilibrium model based on the Rachford-Rice equation. The last four species always remain in the condensed-phase. The 2-mers, 3-mers, and 4-mers are polymer fragments that contain two, three, or four sites, respectively. The residue can contain C, H, N, O, and/or Si. The L-mer fraction consists of polymer fragments that contain at least five sites (5-mer) up to a user defined maximum mer size. The XL-mer fraction consists of polymer fragments greater than the user specified maximum mer size and can contain the infinite lattice if the bridge population is less than the critical bridge population. Model predictions are compared to 133-thermogravimetric

  9. Failure modes and durability of Kevlar/epoxy composites

    SciTech Connect

    Morgan, R.J.; Mones, E.T.; Steele, W.J.; Deutscher, S.B.

    1980-06-04

    The fracture topographies of Kevlar 49/epoxy composite strands and multilayer composites in the form of pressure vessels are discussed in terms of the microscopic deformation and failure processes of the composites. The effect of resin ductility and fiber-matrix interfacial bond strength on mechanisms of fiber damage are considered. The failure of the Kevlar 49 fibers by a splitting process and the parameters, such as fiber fibrillation and macromolecular chain scission, that control such a process, are discussed in relation to fiber and composite performance.

  10. Failure modes and durability of kevlar/epoxy composites

    SciTech Connect

    Morgan, R.J.; Mones, E.T.; Steele, W.J.; Deutscher, S.B.

    1981-04-01

    The fracture topographies of Kevlar 49/epoxy composite strands and multilayer composites in the form of pressure vessels are discussed in terms of the microscopic deformation and failure processes of the composites. The effect of resin ductility and fiber-matrix interfacial bond strength on mechanisms of fiber damage are considered. The failure of the Kevlar 49 fibers by a splitting process and the parameters, such as fiber fibrillation and macromolecular chain scission, that control such a process are discussed in relation to fiber and composite performance.

  11. Lactones. 6. Microbial lactonization of gamma,delta-epoxy esters.

    PubMed

    Olejniczak, T; Gawroński, J; Wawrzeńczyk, C

    2001-06-01

    The ability of 19 microorganisms to perform the enantioselective lactonization of racemic gamma,delta-epoxy ester 3a and its 7-methyl homolog 3b was checked. It was found that Rhodotorula rubra preferentialy transformed both substrates to (-)-enantiomers of trans delta-hydroxy-gamma-lactones with ee 76% for 3a and 24% for 3b. The best efficiency (20-30%) and enantioselectivity (ee 60-100%) of formation of (-)-gamma-hydroxy-delta-lactones 6a and 6b was observed for lactonization by Botrytis cinerea and Fusarium semitectum, respectively.

  12. Impact damage resistance of thin stitched carbon/epoxy laminates

    NASA Astrophysics Data System (ADS)

    Francesconi, L.; Aymerich, F.

    2015-07-01

    The study examines the influence of through-thickness stitching on the damage response of thin cross-ply carbon/epoxy laminates subjected to low-velocity impacts. Instrumented impact tests were carried out on unstitched and polyethylene stitched laminates and the resulting damage was assessed in detail by X-radiography analyses. The results of the observations carried out during the experimental analyses are illustrated and discussed to identify the mechanical role played by through-thickness reinforcement and to highlight the influence of the laminate layup on the impact resistance of stitched laminates.

  13. Crack growth direction in unidirectional off-axis graphite epoxy

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.; Gregory, M. A.; Beuth, J. L., Jr.

    1984-01-01

    An anisotropic elasticity crack tip stress analysis is implemented using three crack extension direction criteria (the normal stress ratio, the tensor polynominal and the strain energy density) to predict the direction of crack extension in unidirectional off axis graphite-epoxy. The theoretical predictions of crack extension direction are then compared with experimental results for 15 deg off axis tensile coupons with center cracks. Specimens of various aspect ratios and crack orientations are analyzed. It is shown that only the normal stress ratio criterion predicts the correct direction of crack growth.

  14. A Study on the Structure and Adhesive Properties of Epoxy-Silicate Composites

    NASA Astrophysics Data System (ADS)

    Brantseva, T. V.; Ilyin, S. O.; Gorbunova, I. Yu.; Antonov, S. V.; Kerber, M. L.

    2014-11-01

    Compositions based on an ED-20 resin with three types of modifiers: natural montmorillonite (MMT) Cloisite Na +, organomodified MMT Cloisite 30B, and halloysite, were investigated. An optimum regime was chosen for preparation of the epoxy/modifier systems by employing the ultrasonic mixing. The rheological characteristics of suspensions were used to estimate the distribution of modifier in the epoxy oligomer. According to rheological data, the best dispersion of MMT in the epoxy oligomer after ultrasonic stirring was observed for the organomodified MMT Cloisite 30B. The maximum shear adhesion strength was also observed for the epoxy resin+Cloisite 30B systems. For the systems with 2 wt. % of Cloisite 30B, the increase in the adhesion strength was up to 65% as compared with that of the pristine epoxy oligomer.

  15. Equilibrium moisture content of a crosslinked epoxy network via molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Stoffels, M. T.; Staiger, M. P.; Bishop, C. M.

    2016-06-01

    This study presents molecular dynamics (MD) simulation methods for determining the solubility limit of water in a crosslinked epoxy network. Procedures are first presented for dynamically crosslinking an epoxy network consisting of diglycidyl ether bisphenol a (DGEBA) and isophorone diamine (IPD). Water molecules are then introduced into the crosslinked DGEBA-IPD structure. The excess chemical potential for the absorbed water was determined through combining thermodynamic integration and Widom’s test particle insertion methods. The limiting moisture uptake of the epoxy structure was determined through comparing the reduced chemical potential of the water held within the epoxy to that of pure water. The DGEBA-IPD epoxy system was found to have a moisture solubility of 3.50-3.75 wt.% when immersed in water at 300 K.

  16. Performance of filament-wound vessels from an organic fiber in several epoxy matrices

    NASA Technical Reports Server (NTRS)

    Chiao, T. T.; Jessop, E. S.; Hamstad, M. A.

    1975-01-01

    A study was carried out to select a state-of-the-art epoxy for wet filament winding. Ten epoxy systems were used to filament wind pressure vessels with a high-modulus, high-strength organic fiber. Data are reported on vessel performance, fiber strand strengths, and shear strengths for the different systems. Using our criteria (processibility, neat resin properties, and vessel performance), we find that an epoxy system based on the rubber-modified bis-phenol-F resin, diluted with vinyl cyclohexane dioxide and cured with mixed aromatic amines, can easily replace bis-phenol-A epoxies diluted with bis-(2, 3-epoxycyclopentyl) ether (such as ERL 2256 epoxy of Union Carbide) with comparable overall performance.

  17. Analysis of acid transport through multi-phase epoxy mortars for wastewater structures.

    PubMed

    Valix, M

    2015-01-01

    The characteristics of acid migration through epoxy mortars were examined. Diffusion coefficients of typical sewer bio-metabolised acids: sulphuric, nitric, citric and oxalic acids were determined by gravimetric sorption method and fitted to the multi-phase Jacob-Jones model. Acid permeation was characterised by hindered pore diffusion with the extent being determined by the polarity of the acid and epoxy, and by the microstructure of the epoxy. Epoxy with higher polarity was able to reduce the diffusion coefficients by 49, while dense phases of the coating reduced the diffusion coefficient by 5,100. These results reflect the relative influence of epoxy polarity and microstructure on their performance as protective liners in sewers.

  18. The Effect of Water on the Work of Adhesion at Epoxy Interfaces by Molecular Dynamics Simulation

    NASA Technical Reports Server (NTRS)

    Hinkley, J.A.; Frankland, S.J.V.; Clancy, T.C.

    2009-01-01

    Molecular dynamics simulation can be used to explore the detailed effects of chemistry on properties of materials. In this paper, two different epoxies found in aerospace resins are modeled using molecular dynamics. The first material, an amine-cured tetrafunctional epoxy, represents a composite matrix resin, while the second represents a 177 C-cured adhesive. Surface energies are derived for both epoxies and the work of adhesion values calculated for the epoxy/epoxy interfaces agree with experiment. Adding water -- to simulate the effect of moisture exposure -- reduced the work of adhesion in one case, and increased it in the other. To explore the difference, the various energy terms that make up the net work of adhesion were compared and the location of the added water was examined.

  19. Optically pure γ-butyrolactones and epoxy esters via two stereocentered HKR of 3-substituted epoxy esters: a formal synthesis of (-)-paroxetine, Ro 67-8867 and (+)-eldanolide.

    PubMed

    Devalankar, Dattatray A; Karabal, Pratibha U; Sudalai, Arumugam

    2013-02-28

    The HKR of racemic anti- or syn-3-substituted epoxy esters catalyzed by a Co(III)salen complex provides ready access to the corresponding enantioenriched 3,4-disubstituted γ-butyrolactones and 3-substituted epoxy esters. This strategy has been successfully employed in the formal synthesis of biologically active 3,4-disubstituted piperidine derivatives, (-)-paroxetine and Ro 67-8867 and a natural product, (+)-eldanolide.

  20. Carbon Nanotube/Cu Nanowires/Epoxy Composite Mats with Improved Thermal and Electrical Conductivity.

    PubMed

    Xing, Yajuan; Cao, Wei; Li, Wei; Chen, Hongyuan; Wang, Miao; Wei, Hanxing; Hu, Dongmei; Chen, Minghai; Li, Qingwen

    2015-04-01

    Polymer composites with carbon nanofillers have been regarded as a promising candidate for electronic package materials. The challenge for such materials is to increase the electrical and thermal conductivity of the composites. Herein, we reported an epoxy composite film with high thermal and electrical conductivity that were prepared by loading high volume fraction of well-dispersed multi-walled carbon nanotubes (MWCNTs, around 50 nm in diameter, 1-10 µm in length) and copper nanowires (Cu NWs, 60-70 nm in diameter, 1-5 µm in length) in epoxy matrix. The MWCNT-Cu NW hybrid mats were prepared by a vacuum filtration method with an optimum Cu NW content of 50 wt%. The hybrid mats was then impregnated by epoxy solution to prepare epoxy composite films. The epoxy was modified by the toughening agent to make the composite films tough and flexible. The loading fraction of MWCNTs and Cu NWs was tuned by controlling the viscosity of epoxy solution. A remarkable synergetic effect between the MWCNTs and Cu NWs in improving the electrical and thermal conductivity of epoxy composites was demonstrated. The results showed that the electrical conductivity of nanocomposites with 42.5 wt% epoxy was 1500 S/m, and the thermal conductivity was 2.83 W/m K, which was 10.1 times of the neat epoxy. Its thermal resistance was as low as 1% of the pure epoxy. And the mechanical properties of composites were also investigated. These robust and flexible nanocomposites showed prospective applications as thermal interface materials (TIMs) in the electronic industry.

  1. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2003-01-01

    Seawater and natural brines accounted for about 60 percent of U.S. magnesium compounds production during 2002. Dead-burned and caustic-calcined magnesias were recovered from seawater by Premier Chemicals in Florida. They were also recovered from well brines in Michigan by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And they were recovered from magnesite in Nevada by Premier Chemicals.

  2. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, seawater and natural brines accounted for 51% of US magnesium compounds production. World magnesia production was estimated to be 14.5 Mt. Most of the production came from China, North Korea, Russia and Turkey. Although no specific production figures are available, Japan and the United States are estimated to account for almost one-half of the world's capacity from seawater and brines.

  3. Evaluation of Nanomaterial Approaches to Damping in Epoxy Resin and Carbon Fiber/Epoxy Composite Structures by Dynamic Mechanical Analysis

    NASA Technical Reports Server (NTRS)

    Miller, G.; Heimann, Paula J.; Scheiman, Daniel A.; Duffy, Kirsten P.; Johnston, J. Chris; Roberts, Gary D.

    2013-01-01

    Vibration mitigation in composite structures has been demonstrated through widely varying methods which include both active and passive damping. Recently, nanomaterials have been investigated as a viable approach to composite vibration damping due to the large surface available to generate energy dissipation through friction. This work evaluates the influence of dispersed nanoparticles on the damping ratio of an epoxy matrix. Limited benefit was observed through dispersion methods, however nanoparticle application as a coating resulting in up to a three-fold increase in damping.

  4. Toughening mechanism in elastometer-modified epoxy resins: Part 1

    NASA Technical Reports Server (NTRS)

    Yee, A. F.; Pearson, R. A.

    1983-01-01

    Several plaques of Epon 828, cured with piperidine, modified with hycar(r) CTBN 1300X8, Hycar(R) CTBN 1300X13, and Hycar(R) CTBN 1300x15, and in some cases modified with biphenol A (BPA), yielded properly toughened epoxies with rubber particle diameters ranging from 0.1 to 10 microns. Fracture toughness experiments indicate that toughness was more a function of rubber content than the rubber particle size. Tensile volumetric behavior of the near resin exhibits two regions: an initial region where the increase in volume strain was due to the Poisson's effect, and a second region where a slower rate of increase in volume strain was due to shear deformation. Tensile volumetric deformation of an elastomer-modified epoxy exhibits the same type of behavior to that of the neat resin at low rates ( 3.2x0.01 sec(-1)). But at very high strain rates, which correspond more closely to the strain rates at the crack tip, there exists an increase in volume strain beyond the Poisson's effect. TEM, SEM and OM studies indicate that the rubber particles had voided. When a thin section from the deformed region is viewed under crossed-polarized light, shear bands are seen connecting voided rubber particles. From this information cavitation and enhanced shear band formation is proposed as the toughening mechanism.

  5. [Study of mutagenicity of epoxy resin hardeners by fluctuation test].

    PubMed

    Hayashi, K; Koike, N; Mashizu, N; Mozawa, K; Sakaba, H; Shimizu, H

    1987-11-01

    Mutagenicity of nine epoxy resin hardeners was examined by a fluctuation test modified by Gatehouse. The test was performed by using Salmonella typhimurium TA98 with a metabolic activation system. In our laboratory, the results of the fluctuation test were compared with the results obtained by the previously mentioned Ames preincubation method. Six out of nine epoxy resin hardeners showed mutagenic activity in both the fluctuation test and Ames preincubation method, but one out of the nine was negative in both test systems. Two out of the nine were positive by either of the two testing systems. The fluctuation test is disadvantageous in that it is marginally slower and requires slightly more labor than the Ames test and furthermore it is difficult to increase the amount of microsome because of background interference. These disadvantages, however, are somewhat offset by the advantages that small organs such as urinary bladder can be used instead of liver cells and that a small amount of microsome can be employed for metabolic activation. This test is also suitable for testing aqueous samples containing low levels of mutagen.

  6. Shock Interaction Studies on Glass Fibre Reinforced Epoxy Matrix Composites

    NASA Astrophysics Data System (ADS)

    Reddy, K. P. J.; Jagadeesh, G.; Jayaram, V.; Reddy, B. Harinath; Madhu, V.; Reddy, C. Jaya Rami

    Glass fibre reinforced polymer matrix composites are being extensively used for structural applications both in civil and defense sectors, owing to their high specific strength, stiffness and good energy absorbing capability. Understanding the dynamic response of these composites on shock loading is very essential for effective design of structures resistant to blast loads. In the present study, E- glass/epoxy composite laminate has been fabricated and evaluated for their mechanical properties such as tensile strength, flexural strength and inter laminar shear strength (ILSS). Further, dynamic response of E-glass laminates is presently studied by shock loading. When E-glass composite subjected to peak shock reflected pressure of 7.2 MPa and estimated temperature of about 14000 K for short duration, it underwent surface discolorations and charring of epoxy matrix. Post test analysis of the composite sample was carried out to study the damage analysis using Scanning Electron Microscope (SEM), changes in thermal properties of composites using Dynamic Mechanical Analyzer (DMA) and Thermo-Gravimetric Analyzer (TGA). The results of these investigations are discussed in this paper.

  7. Continuous health monitoring of graphite epoxy motorcases (GEM)

    NASA Astrophysics Data System (ADS)

    Finlayson, Richard D.; Luzio, Marco A.; Miller, Ronnie K.; Pollock, Adrian A.

    2003-08-01

    With the increasing use of advanced composite materials in aircraft, automobiles, military hardware, and aerospace composites (such as rocket motorcases) a sizable need for composite health assessment measures exist, particularly where there is risk of failure due to high mechanical and thermal stresses. For most epoxy-based laminate composites, even low-momentum impacts can lead to "barely visible impact damage" (BVD), corresponding to a significant weakening of the composite. This weakening can lead to sudden and catastrophic failure when the material is subjected to normal operating loads. Following the explosion of Delta 241 (IIR-1) on Jaunary 17th, 1997, the failure investigation board concluded that an entire fleet of Graphite Epoxy Motorcases (GEMs) should be instrumented with a health monitoring system. This system would provide continuous structural health data on the GEM from initial acceptance testing through final erection on the launch pad. The result presented here contribute significantly to the understanding of the acoustic properties of the GEM casing, and make a substantial advancement in the theoretical phase of the source location algorithm development. When the system is complete it will continuously monitor the structural health of the GEMs, communicate wirelessly with base stations, operate autonomously for extended periods, and fit unobtrusively on the GEM itself.

  8. Temperature-Dependent Dielectric Properties of Al/Epoxy Nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Zijun; Zhou, Wenying; Sui, Xuezhen; Dong, Lina; Cai, Huiwu; Zuo, Jing; Chen, Qingguo

    2016-06-01

    Broadband dielectric spectroscopy was carried out to study the transition in electrical properties of Al/epoxy nanocomposites over the frequency range of 1-107 Hz and the temperature range of -20°C to 200°C. The dielectric permittivity, dissipation factor, and electrical conductivity of the nanocomposites increased with temperature and showed an abrupt increase around the glass transition temperature ( T g). The results clearly reveal an interesting transition of the electrical properties with increasing temperature: insulator below 70°C, conductor at about 70°C. The behavior of the transition in electrical properties of the nanocomposites was explored at different temperatures. The presence of relaxation peaks in the loss tangent and electric modulus spectra of the nanocomposites confirms that the chain segmental dynamics of the polymer is accompanied by the absorption of energy given to the system. It is suggested that the temperature-dependent transition of the electric properties in the nanocomposite is closely associated with the α-relaxation. The large increase in the dissipation factor and electric conductivity depends on the direct current conduction of thermally activated charge carriers resulting from the epoxy matrix above T g.

  9. Dispersion monitoring of carbon nanotube modified epoxy systems

    NASA Astrophysics Data System (ADS)

    Gkikas, G.; Saganas, Ch.; Grammatikos, S. A.; Maistros, Gh. M.; Barkoula, N.-M.; Paipetis, A. S.

    2012-04-01

    The remarkable mechanical and electrical properties exhibited by carbon nanotubes (CNTs) have encouraged efforts to develop mass production techniques. As a result, CNTs are becoming increasingly available, and more attention from both the academic world and industry has focused on the applications of CNTs in bulk quantities. These opportunities include the use of CNTs as conductive filler in insulating polymer matrices and as reinforcement in structural materials. The use of composites made from an insulating matrix and highly conductive fillers is becoming more and more important due to their ability to electromagnetically shield and prevent electrostatic charging of electronic devices. In recent years, different models have been proposed to explain the formation of the conductive filler network. Moreover, intrinsic difficulties and unresolved issues related to the incorporation of carbon nanotubes as conductive fillers in an epoxy matrix and the interpretation of the processing behavior have not yet been resolved. In this sense, a further challenge is becoming more and more important in composite processing: cure monitoring and optimization. This paper considers the potential for real-time control of cure cycle and dispersion of a modified epoxy resin system commonly utilized in aerospace composite parts. It shows how cure cycle and dispersion control may become possible through realtime in-situ acquisition of dielectric signal from the curing resin, analysis of its main components and identification of the significant features.

  10. The electron beam cure of epoxy paste adhesives

    SciTech Connect

    Farmer, J.D.; Janke, C.J.; Lopata, V.J.

    1998-07-01

    Recently developed epoxy paste adhesives were electron beam cured and experimentally explored to determine their suitability for use in an aerospace-quality aircraft component. There were two major goals for this program. The first was to determine whether the electron beam-curable past adhesives were capable of meeting the requirements of the US Air Force T-38 supersonic jet trainer composite windshield frame. The T-38 windshield frame`s arch is currently manufactured by bonding thin stainless steel plies using an aerospace-grade thermally-cured epoxy film adhesive. The second goal was to develop the lowest cost hand layup and debulk process that could be used to produce laminated steel plies with acceptable properties. The laminate properties examined to determine adhesive suitability include laminate mechanical and physical properties at room, adhesive tack, out-time capability, and the debulk requirements needed to achieve these properties. Eighteen past adhesives and four scrim cloths were experimentally examined using this criteria. One paste adhesive was found to have suitable characteristics in each of these categories and was later chosen for the manufacture of the T-38 windshield frame. This experimental study shows that by using low-cost debulk and layup processes, the electron beam-cured past adhesive mechanical and physical properties meet the specifications of the T-38 composite windshield frame.

  11. A Dioxane Template for Highly Selective Epoxy Alcohol Cyclizations

    PubMed Central

    Mousseau, James J.; Morten, Christopher J.

    2013-01-01

    Ladder polyether natural products are a class of natural products denoted by their high functional group density and large number of well-defined stereocenters. They comprise the toxic component of harmful algal blooms (HABs), having significant negative economic and environmental ramifications. However, their mode of action, namely blocking various cellular ion channels, also denotes their promise as potential anticancer agents. Understanding their potential mode of biosynthesis will not only help with developing ways to limit the damage of HABs, but would also facilitate the synthesis of a range of analogues with interesting biological activity. 1,3-Dioxan-5-ol substrates display remarkable ‘enhanced template effects’ in water-promoted epoxide cyclization processes en route to the synthesis of these ladder polyether natural products. In many cases they provide near complete endo to exo selectivity in the cyclization of epoxy alcohols, thereby strongly favouring the formation of tetrahydropyran (THP) over tetrahydrofuran (THF) rings. The effects of various Brønsted and Lewis acidic and basic conditions are explored to demonstrate the superior selectivity of the template over the previously reported THP-based epoxy alcohols. In addition, the consideration of other synthetic routes are also considered with the goal of gaining rapid access to a plethora of potential starting materials applicable towards the synthesis of ladder polyethers. Finally, cascade sequences with polyepoxides are investigated, further demonstrating the versatility of this new reaction template. PMID:23775936

  12. Laser decontamination of epoxy painted concrete surfaces in nuclear plants

    NASA Astrophysics Data System (ADS)

    Anthofer, A.; Lippmann, W.; Hurtado, A.

    2014-04-01

    Laser technology offers an efficient decontamination of surfaces contaminated by polychlorinated biphenyls (PCB) by precise application of highly focused laser beam power. In the context of nuclear decommissioning all walls and floors of a reactor building have to be cleaned from chemical-toxic substances. State of the art is a manual and mechanic ablation and a subsequent treatment in a hazardous waste incinerator. In this study, alternatively, a laser-based system exhibiting, decontamination rates of up to 6.4 m2/h has been operated using a 10 kW diode laser in continuous wave (CW) mode with a spot size of 45×10 mm2 and a wavelength of 980-1030 nm. The system allows a rapid heating of the surfaces up to temperatures of more than 1000 °C leading to ablation and thermal decomposition of PCB in one process step. Thermal quenching prevents formation of polychlorinated dioxines (PCDD) and polychlorinate furans (PCDF) in the flue gas. Additionally, an in situ measurement system based on laser induced fluorescence (LIF) is developed to monitor the thermal decomposition of PCB. For initial experiments samples covered with epoxy paint were used to evaluate the process and to carry out finite element based simulations. In this paper, experimental results of ablation tests by laser irradiation of epoxy painted concrete are presented and discussed.

  13. Highly dispersed nanosilica-epoxy resins with enhanced mechanical properties

    SciTech Connect

    Chen, Chenggang; Justice, Ryan S; Schaefer, Dale W; Baur, Jeffery W

    2009-08-31

    Epoxy-nanocomposite resins filled with 12-nm spherical silica particles were investigated for their thermal and mechanical properties as a function of silica loading. The nanoparticles were easily dispersed with minimal aggregation for loadings up to 25 wt% as determined using transmission electron microscopy (TEM) and ultra-small-angle X-ray scattering (USAXS). A proportional decrease in cure temperatures and glass transition temperature (for loadings of 10 wt% and above) was observed with increased silica loading. The morphology determined by USAXS is consistent with a zone around the silica particles from which neighboring particles are excluded. The 'exclusion zone' extends to 10x the particle diameter. For samples with loadings less than 10 wt%, increases of 25% in tensile modulus and 30% in fracture toughness were obtained. More highly loaded samples continued to increase in modulus, but decreased in strength and fracture toughness. Overall, the addition of nanosilica is shown as a promising method for property enhancement of aerospace epoxy composite resins.

  14. Thermoviscoelastic characterization and predictions of Kevlar/epoxy composite laminates

    SciTech Connect

    Gramoll, K.C.

    1988-01-01

    This study consisted of two main parts, the thermoviscoelastic characterization of Kevlar 49/Fiberite 7714A epoxy composite lamina and the development of a numerical procedure to predict the viscoelastic response of any general laminate constructed from the same material. The four orthotropic material properties, S{sub 11}, S{sub 12}, S{sub 22}, and S{sub 66}, were characterized by 20-minute static creep tests on unidirectional ((0){sub s}, (10){sub s}, and (90){sub 16}) lamina specimens. A new numerical procedure to predict long-term laminate properties from lamina properties (obtained experimentally) was developed. Numerical instabilities and time constraints associated with viscoelastic numerical techniques were discussed and solved. The numerical procedure was incorporated into a user-friendly microcomputer program called Viscoelastic Composite Analysis Program (VCAP), which is available for IBM PC type computers. The program was designed for ease of use and includes graphics, menus, help messages, etc. The final phase of the study involved testing actual laminates constructed from the characterized material, Kevlar/epoxy, at various temperature and load levels for 4 to 5 weeks.

  15. Interlocked fabric and laminated fabric Kevlar 49/epoxy composites

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.

    1988-01-01

    The mechanical behavior of a novel interlocked fabric reinforced Kevlar 49/epoxy composite has been measured and compared to those of a laminated Kevlar 49 fabric composite (which served as a reference material). Both composites were 5.0 mm thick, contained the same 50% in-plane fiber volume fraction and were fabricated in a similar manner using the same Dow DER 332 epoxy, Jeffamine T403-hardened resin system. The reference material (Material 1) was reinforced with seven plies of Dupont style 1033 Kevlar 49 fabric. A photomicrograph of a section polished parallel to one of the fiber directions is shown. The interlocked fabric was designed and woven for Sandia National Laboratories by Albany International Research Co., Dedham, MA. The main design criterion was to duplicate a sewn through-the-thickness fabric used in preliminary studies. The interlocked fabric composite (Material 2) contains roughly 4% by volume of through-the-thickness fiber reinforcement for the purpose of improving interlaminar strength. A photomicrograph of a section showing the warp-aligned binder yarns interlocking the six fabric plies together is shown. 2 refs., 8 figs.

  16. An evaluation of composites fabricated from powder epoxy towpreg

    NASA Technical Reports Server (NTRS)

    Hartness, J. Timothy; Greene, Tim

    1992-01-01

    BASF has developed a unique process for applying powdered resin systems to continuous reinforcement fibers in order to produce flexible towpreg material. Evaluation of three powder epoxy resins using this towpregging process is in progress under NASA contract NAS1-18834. Shell RSS-1952, Dow CET-3, and 3M PR 500 powder epoxy systems have been successfully towpregged with G30-500 6K carbon fiber. Both neat resin and basic unidirectional composite properties have been developed to compare performance. Cure cycles for each system have also been developed for repeatable fabrication of high-quality composite laminates. Evaluations of the powder towpreg material for use in textiles processes such as weaving and braiding are underway. Traditional 8-harness weaving has been successfully performed with one system (PR500/G30-500) to date, with some basic composite properties generated. Ongoing work will demonstrate scaleup of the towpregging process for higher throughput, as well as evaluation of the powder towpreg material in advanced preforming processes such as 3-D braiding and weaving. An outline and figures summarize the research results.

  17. Cure kinetics of epoxy matrix resin by differential scanning calorimetry

    NASA Technical Reports Server (NTRS)

    Cizmecioglu, M.; Gupta, A.

    1982-01-01

    A study was made on the cure kinetics of an epoxy neat-resin (Narmco 5208) using Differential Scanning Calorimetry (DSC). Two interrelated analytical methods were applied to dynamic DSC data for evaluating the kinetic parameters, such as activation energy, E, the order of reaction, n, and the total heat of polymerization (or crosslinking), delta H sub t. The first method was proposed by Ellerstein (1968), and uses a thorough differential-integral analysis of a single DSC curve to evaluate the kinetic parameters. The second method was proposed by Kissinger (1957), and uses multiple DSC curves obtained at various heating rates to evaluate E regardless of n. Kinetic analysis of Narmco 5208 epoxy resin showed that the reaction order, n, is substantially affected by the rate of heating; i.e., n is approximately 2 at slow scan rates but is reduced to 1.5 at higher scan rates. The activation energy, E, is not affected by the scan rate, and the average value of E is 25.6 + or - 1.8 kcal/mole.

  18. Sensing delamination in epoxy encapsulant systems with fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Jones, Brad H.; Rohr, Garth D.; Kaczmarowski, Amy K.

    2016-05-01

    Fiber Bragg gratings (FBGs) are well-suited for embedded sensing of interfacial phenomena in materials systems, due to the sensitivity of their spectral response to locally non-uniform strain fields. Over the last 15 years, FBGs have been successfully employed to sense delamination at interfaces, with a clear emphasis on planar events induced by transverse cracks in fiber-reinforced plastic laminates. We have built upon this work by utilizing FBGs to detect circular delamination events at the interface between epoxy films and alumina substrates. Two different delamination processes are examined, based on stress relief induced by indentation of the epoxy film or by cooling to low temperature. We have characterized the spectral response pre- and post-delamination for both simple and chirped FBGs as a function of delamination size. We show that delamination is readily detected by the evolution of a non-uniform strain distribution along the fiber axis that persists after the stressing condition is removed. These residual strain distributions differ substantially between the delamination processes, with indentation and cooling producing predominantly tensile and compressive strain, respectively, that are well-captured by Gaussian profiles. More importantly, we observe a strong correlation between spectrally-derived measurements, such as spectral widths, and delamination size. Our results further highlight the unique capabilities of FBGs as diagnostic tools for sensing delamination in materials systems.

  19. Physical properties of epoxy resin/titanium dioxide nanocomposites

    SciTech Connect

    Polyzos, Georgios; Tuncer, Enis; Sauers, Isidor; More, Karren Leslie

    2011-01-01

    A polymeric nanocomposite system (nanodielectric) was fabricated, and its mechanical properties were determined. The fabricated nanocomposite was composed of low concentrations of monodispersed titanium dioxide (TiO{sub 2}) nanoparticles and an epoxy resin specially designed for cryogenic applications. The monodispersed TiO{sub 2} nanoparticles were synthesized in an aqueous solution of titanium chloride and polyethylene glycol and subsequently dispersed in a commercial-grade epoxy resin (Araldite{reg_sign} 5808). Nanocomposite thin sheets were prepared at several weight fractions of TiO{sub 2}. The morphology of the composites, determined by transmission electron microscopy, showed that the nanoparticles aggregated to form particle clusters. The influence of thermal processing and the effect of filler dispersion on the structure-property relationships were identified by differential scanning calorimetry and dynamic mechanical analysis at a broad range of temperatures. The effect of the aggregates on the electrical insulation properties was determined by dielectric breakdown measurements. The optical properties of the nanocomposites and their potential use as filters in the ultraviolet-visible (UV-vis) range were determined by UV-vis spectroscopy.

  20. Physical, morphological, and chemical studies of dusts derived from the machining of composite-epoxy materials.

    PubMed

    Boatman, E S; Covert, D; Kalman, D; Luchtel, D; Omenn, G S

    1988-04-01

    This work (in three parts) inquires into whether respirable dusts derived from the machining of six composite-epoxy materials (e.g., aircraft industry) may pose a health risk to the operators. Dust samples representative of a variety of composites and structural components were aerodynamically sized and fractionated. Bulk and fractionated samples were examined by light and electron microscopy and analyzed chemically by thermogravimetry (TGA), gas chromatography (GC) and mass spectrometry (MS). Relative fractions of respirable to total mass of bulk samples were less than 3%; aerodynamic diameters of fractionated particles ranged from 0.8 to 2.0 microns. By microscopy, bulk particles ranged from 7 to 11 microns in diameter, with mean aspect ratios from 4 to 8:1. Mean diameter of fractionated particles was 2.7 microns. By TGA, weight losses were negligible below 250 degrees C and variable but elevated at temperatures up to 860 degrees C. In assays of vapors released at 250 degrees C, GC/MS indicated a variety of compounds in different amounts for each sample. We conclude that under the present machining protocols, dusts at the tool face contained few particles of respirable size with no evidence of splitting of fibers longitudinally and were of a low volatilizable chemical content. Overall, composites were judged to be well cured and thermally stable.

  1. Automated multisyringe stir bar sorptive extraction using robust montmorillonite/epoxy-coated stir bars.

    PubMed

    Ghani, Milad; Saraji, Mohammad; Maya, Fernando; Cerdà, Víctor

    2016-05-06

    Herein we present a simple, rapid and low cost strategy for the preparation of robust stir bar coatings based on the combination of montmorillonite with epoxy resin. The composite stir bar was implemented in a novel automated multisyringe stir bar sorptive extraction system (MS-SBSE), and applied to the extraction of four chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) as model compounds, followed by high performance liquid chromatography-diode array detection. The different experimental parameters of the MS-SBSE, such as sample volume, selection of the desorption solvent, desorption volume, desorption time, sample solution pH, salt effect and extraction time were studied. Under the optimum conditions, the detection limits were between 0.02 and 0.34μgL(-1). Relative standard deviations (RSD) of the method for the analytes at 10μgL(-1) concentration level ranged from 3.5% to 4.1% (as intra-day RSD) and from 3.9% to 4.3% (as inter-day RSD at 50μgL(-1) concentration level). Batch-to-batch reproducibility for three different stir bars was 4.6-5.1%. The enrichment factors were between 30 and 49. In order to investigate the capability of the developed technique for real sample analysis, well water, wastewater and leachates from a solid waste treatment plant were satisfactorily analyzed.

  2. Controlled Contamination of Epoxy Composites with PDMS and Removal by Laser Ablation

    NASA Technical Reports Server (NTRS)

    Palmieri, Frank; Ledesma, Rodolfo; Cataldo, Daniel; Lin, Yi; Wohl, Christopher; Gupta, Mool; Connell, John

    2016-01-01

    Surface preparation is critical to the performance of adhesively bonded composites. During manufacturing, minute quantities of mold release compounds are inevitably deposited on faying surfaces and may compromise bond performance. To ensure safety, mechanical fasteners and other crack arrest features must be installed in the bondlines of primary structures, which negates some advantages of adhesively bonded construction. Laser ablation is an automated, repeatable, and scalable process with high potential for the surface preparation of metals and composites in critical applications such as primary airframe structures. In this study, laser ablation is evaluated on composite surfaces for the removal of polydimethylsiloxane (PDMS), a common mold release material. Composite panels were contaminated uniformly with PDMS film thicknesses as low as 6.0 nm as measured by variable angle spectroscopic ellipsometry. Bond performance was assessed by mechanical testing using a 250 F cure, epoxy adhesive and compared with pre-bond surface inspection results. Water contact angle, optically stimulated electron emission, and laser induced breakdown spectroscopy were used to characterize contaminated and laser ablated surfaces. The failure mode obtained from double cantilever beam tests correlated well with surface characterization data. The test results indicated that even low levels of PDMS were not completely removed by laser ablation.

  3. Novel Organically Modified Core-Shell Clay for Epoxy Composites—“SOBM Filler 1”

    PubMed Central

    Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

    2014-01-01

    Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm−1 and 1435 cm−1, respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties. PMID:27355022

  4. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2002-01-01

    Seawater and natural brines accounted for about 60% of US magnesium compounds production in 2001. Dead-burned and caustic-calcined magnesias were recovered from seawater in Florida by Premier Chemicals. They were also recovered from Michigan well brines by Dow Chemical, Martin Marietta Magnesia Specialties and Rohm & Haas. And Premier Chemicals recovered dead-burned and caustic-calcined magnesias from magnesite in Nevada. Reilly Industries and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

  5. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2011-01-01

    Seawater and natural brines accounted for about 54 percent of U.S. magnesium compounds production in 2010. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash-Wendover and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its operation mentioned above.

  6. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2010-01-01

    Seawater and natural brines accounted for about 40 percent of U.S. magnesium compounds production in 2009. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Chemicals in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover, and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta from its operation mentioned above.

  7. Water absorption behavior and residual strength assessment of glass/epoxy and glass-carbon/epoxy hybrid composite

    NASA Astrophysics Data System (ADS)

    Mohanty, S. C.; Singh, B. P.; Mahato, K. K.; Rathore, D. K.; Prusty, R. K.; Ray, B. C.

    2016-02-01

    Present investigation is aimed to study the water absorption behaviour and evaluation of residual strength of glass fibre/epoxy (GE) and alternate plies of glass- carbon/epoxy (GCE) hybrid composite. Both the composite systems were exposed to water at 70°C. Specimens were weighed after certain time periods to study the water uptake kinetic. Flexural tests were conducted after 4, 100 and 450 hours of ageing to evaluate the effect of hot water ageing on the mechanical properties of these potential materials. The water uptake kinetic was found to follow Fickian diffusion kinetic for GE as well as GCE hybrid composite but the rate of diffusion was higher for GE composite over GCE composite. The water content was also higher in GE composite over GCE composite after 450 hours of ageing. Significant decrement in flexural strength was observed with the increase in ageing time. Presence of water in the composite also imparted significant embrittlement to the matrix as reflected in the decrease in strain at peak for both the composite systems.

  8. Heat transfer through cyanate ester epoxy mix and epoxy TGPAP - DETDA electrical insulations at superfluid helium temperature

    NASA Astrophysics Data System (ADS)

    Pietrowicz, Slawomir; Four, Aurelian; Canfer, Simon; Jones, Stephanie; Baudouy, Bertrand

    2012-06-01

    A high magnetic field accelerator magnet of 13 T is being developed in Work Package 7 of the European Union FP7 project EuCARD. The application is to enable higher luminosities and energies for accelerators such as the LHC. The high magnetic field demands superconductors that require a heat treatment step such as Nb3Sn. This paper reports thermal tests on conventional composite electrical insulation with pressurized superfluid helium at atmospheric pressure as a coolant. Two composite insulation systems composed of cyanate ester epoxy mix or a tri-functional epoxy (TGPAP-DETDA) with Sglass fiber, have been chosen as candidate materials. The knowledge of their thermal properties is necessary for the thermal design and therefore samples have been tested in pressurized He II where heat is applied perpendicularly to the fibers between 1.6 K and 2.0 K. Overall thermal resistance is determined as a function of temperature and the results are compared with other electrical insulation systems used for accelerator magnets.

  9. Superior Mechanical Properties of Epoxy Composites Reinforced by 3D Interconnected Graphene Skeleton.

    PubMed

    Ni, Ya; Chen, Lei; Teng, Kunyue; Shi, Jie; Qian, Xiaoming; Xu, Zhiwei; Tian, Xu; Hu, Chuansheng; Ma, Meijun

    2015-06-03

    Epoxy-based composites reinforced by three-dimensional graphene skeleton (3DGS) were fabricated in resin transfer molding method with respect to the difficulty in good dispersion and arrangement of graphene sheets in composites by directly mixing graphene and epoxy. 3DGS was synthesized in the process of self-assembly and reduction with poly(amidoamine) dendrimers. In the formation of 3DGS, graphene sheets were in good dispersion and ordered state, which resulted in exceptional mechanical properties and thermal stability for epoxy composites. For 3DGS/epoxy composites, the tensile and compressive strengths significantly increased by 120.9% and 148.3%, respectively, as well as the glass transition temperature, which increased by a notable 19 °C, unlike the thermal exfoliation graphene/epoxy composites via direct-mixing route, which increased by only 0.20 wt % content of fillers. Relative to the graphene/epoxy composites in direct-mixing method mentioned in literature, the increase in tensile and compressive strengths of 3DGS/epoxy composites was at least twofold and sevenfold, respectively. It can be expected that 3DGS, which comes from preforming graphene sheets orderly and dispersedly, would replace graphene nanosheets in polymer nanocomposite reinforcement and endow composites with unique structure and some unexpected performance.

  10. Magnetic epoxy nanocomposites with superparamagnetic MnFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Huang, Jiangnan; Cao, Yonghai; Zhang, Xi; Li, Yutong; Guo, Jiang; Wei, Suying; Peng, Xiangfang; Shen, Tong D.; Guo, Zhanhu

    2015-09-01

    Manganese iron oxide (MnFe2O4) nanoparticles successfully served as nanofillers for obtaining magnetic epoxy nanocomposites. The viscosities of MnFe2O4/epoxy resin liquid suspensions increased with increasing the nanoparticles loading except the suspension with 5.0 and 1.0 wt% loading, whose viscosities were lower than that of pure epoxy. The introduction of MnFe2O4 nanoparticles showed a lower onset decomposition temperature and glass transition temperature (Tg), which decreased with increasing the nanoparticles loading. The storage modulus and tensile strength of 1.0 wt% MnFe2O4/epoxy were a little higher than that of pure epoxy. The coercivity of MnFe2O4/epoxy nanocomposites with 5.0 wt% (44.7 Oe) and 10.0 wt% (43.9 Oe) displayed much higher than that of pure MnFe2O4 nanoparticles (14.94 Oe). The magnetic moment (m) of nanocomposites (1.354 μB for 10 wt% MnFe2O4/epoxy) are higher than that of pure MnFe2O4 nanoparticles (1.244 μB). The increased real permittivity observed in the nanocomposites was attributed to the interfacial polarization. The intrinsic permittivity of the MnFe2O4 nanoparticles was also calculated.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Impact properties of rubber-modified epoxy resin-graphite-fiber composites

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J.; Nir, Z.

    1984-01-01

    To improve the impact resistance of graphite-fiber composites, a commercial and an experimental epoxy resin were modified with liquid reactive rubber and a brominated epoxy resin. The commercial epoxy was a tetrafunctional resin, and the experimental epoxy was a trifunctional resin. The reactive rubber was a carboxyl-terminated butadiene-acrylonitrile copolymer. The rubber content was varied from 0 to 25 percent (wt). The brominated epoxy resin was used at Br levels of 4, 19, and 35 percent of the resin. Composites were prepared with woven graphite cloth reinforcement. The composites were evaluated by using flexural strength in the dry state and an elevated temperature after saturation with water. The impact properties were determined by measuring shear strength after falling-ball impact and instrumented impact. The rubber-modified, trifunctional resin exhibited better properties, when tested in hot-wet conditions in a heated oven at 366 K (after boiling the material for 2 h in demineralized water), than the tetrafunctional resin. Improved impact resistance was observed with the addition of the reactive rubber to the epoxy resin. Further improvement was observed with the addition of the brominated epoxy resin.

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

    PubMed

    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.

  14. Modification of epoxy resin, silicon and glass surfaces with alkyl- or fluoroalkylsilanes for hydrophobic properties

    NASA Astrophysics Data System (ADS)

    Marczak, Jacek; Kargol, Marta; Psarski, Maciej; Celichowski, Grzegorz

    2016-09-01

    Preparation of superhydrophobic materials inspired by nature has attracted a great scientific interest in recent decades. Some of these materials have hierarchical lotus-like structures, i.e. micro- and nano-objects coated by hydrophobic compounds. A major challenge of applying the superhydrophobic surfaces for the self-cleaning coatings preparation is their improved efficiency in varying atmospheric conditions, e.g. UV light. The objective of this research work was to investigate the effect of the different chemical structure and the surface free energy on the hydrophobic and tribological properties of the alkylsilanes and fluoroalkylsilanes deposited on silicon wafers, glass slides and epoxy resin. Tribological and hydrophobic properties of the modified surfaces were correlated with their chemical structures. Chemical structures of the deposited materials were examined by using Fourier transform infrared (FT-IR) spectroscopy and hydrophobic properties were investigated by water contact angle (WCA) and surface free energy (SFE) measurements. The modified surfaces exhibited water contact angles of above 100° for the selected modifiers. It was noticed that the replacement of hydrogen atoms by fluorine atoms in alkyl chain caused an increase in the water contact angle values and a decrease in friction coefficients. The obtained results showed that the carbon chain length of a modifier and its chemical structure can strongly affect the hydrophobic and tribological properties of the modified surfaces. The highest values of WCA, lowest values of SFE and coefficient of friction were obtained for samples covered by fluorinated compounds. Moreover, some preliminary aging test was performed to give an insight into the effectiveness of deposited alkylsilanes and fluoroalkylsilanes coatings. After accelerated UV exposure, no significant changes in the chemical structure, hydrophobic and tribological properties of the modified surfaces were noticed. The samples degradation

  15. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Seawater and natural brines accounted for about 52 percent of U.S. magnesium compounds production in 2006. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Potash-Wendover and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from brucite by Applied Chemical Magnesias in Texas, from seawater by SPI Pharma in Delaware and Premier Chemicals in Florida, and by Martin Marietta and Rohm and Haas from their operations mentioned above. About 59 percent of the magnesium compounds consumed in the United States was used for refractories that are used mainly to line steelmaking furnaces. The remaining 41 percent was consumed in agricultural, chemical, construction, environmental and industrial applications.

  16. Intermetallic Compounds

    NASA Astrophysics Data System (ADS)

    Takagiwa, Y.; Matsuura, Y.; Kimura, K.

    2014-06-01

    We have focused on the binary narrow-bandgap intermetallic compounds FeGa3 and RuGa3 as thermoelectric materials. Their crystal structure is FeGa3-type (tetragonal, P42/ mnm) with 16 atoms per unit cell. Despite their simple crystal structure, their room temperature thermal conductivity is in the range 4-5-W-m-1-K-1. Both compounds have narrow-bandgaps of approximately 0.3-eV near the Fermi level. Because their Seebeck coefficients are quite large negative values in the range 350-<-| S 373K|-<-550- μV-K-1 for undoped samples, it should be possible to obtain highly efficient thermoelectric materials both by adjusting the carrier concentration and by reducing the thermal conductivity. Here, we report the effects of doping on the thermoelectric properties of FeGa3 and RuGa3 as n and p-type materials. The dimensionless figure of merit, ZT, was significantly improved by substitution of Sn for Ga in FeGa3 (electron-doping) and by substitution of Zn for Ga in RuGa3 (hole-doping), mainly as a result of optimization of the electronic part, S 2 σ.

  17. Characterization of paint samples used in drinking water reservoirs: identification of endocrine disruptor compounds.

    PubMed

    Romero, J; Ventura, F; Gomez, M

    2002-04-01

    Several migration tests are performed from various epoxy paint samples that, according to the regulation, can be used in food reservoirs such as drinking water reservoirs. The level of the organic compounds capable of producing migrations to water with special attention to endocrine disruptor compounds (EDCs) are identified and estimated by closed loop-stripping analysis (CLSA) and liquid-liquid extraction (LLE) methods coupled with gas chromatography (GC)-mass spectrometry (MS). Bisphenol A, a strong endocrine disruptor, is found in all migration experiments. Its concentration level reaches between 0.02 and 0.03 mg/cm2. The higher concentration corresponds with benzylic alcohol, which is used as a solvent and curing agent in epoxy paint. Other EDCs identified in the migration tests are phthalates, 4-nonylphenol, and t-butylphenol. The main non-EDCs identified are solvents, antioxidants, and rubber-like compounds. No great differences are found in the use of metallic plates or concrete slabs for migration experiments; only additional compounds related with the pretreatment of the concrete wall have been identified, too. In the study of a drinking water sample the same organic compounds identified in the migration test is not seen. This is probably because of the dynamic situation in a drinking water reservoir. Finally, a GC profile of a direct epoxy paint analysis is shown. The main peak identified is bisphenol A diglycidyl ether, monomer, and an active principle of the polymerization of epoxy resins based on bisphenol A. In addition, we report the recoveries of a selected group of EDCs using CLSA and LLE methods coupled with GC-MS.

  18. Filled and Unfilled Temperature-Dependent Epoxy Resin Blends for Lossy Transducer Substrates

    PubMed Central

    Eames, Matthew D.C.; Hossack, John A.

    2016-01-01

    In the context of our ongoing investigation of low-cost 2-dimensional (2-D) arrays, we studied the temperature-dependent acoustic properties of epoxy blends that could serve as an acoustically lossy backing material in compact 2-D array-based devices. This material should be capable of being machined during array manufacture, while also providing adequate signal attenuation to mitigate backing block reverberation artifacts. The acoustic impedance and attenuation of 5 unfilled epoxy blends and 2 filled epoxy blends—tungsten and fiberglass fillers—were analyzed across a 35°C temperature range in 5°C increments. Unfilled epoxy materials possessed an approximately linear variation of impedance and sigmoidal variation of attenuation properties over the range of temperatures of interest. An intermediate epoxy blend was fitted to a quadratic trend line with R2 values of 0.94 and 0.99 for attenuation and impedance, respectively. It was observed that a fiberglass filler induces a strong quadratic trend in the impedance data with temperature, which results in increased error in the characterization of attenuation and impedance. The tungsten-filled epoxy was not susceptible to such problems because a different method of fabrication was required. At body temperature, the tungsten-filled epoxy could provide a 44 dB attenuation of the round-trip backing block echo in our application, in which the center frequency is 5 MHz and the backing material is 1.1 mm thick. This is an 11 dB increase in attenuation compared with the fiberglass-filled epoxy in the context of our application. This work provides motivation for exploring the use of custom-made tungsten-filled epoxy materials as a substitute PCB-based substrate to provide electrical signal interconnect. PMID:19406716

  19. Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

    PubMed

    Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

    2012-11-01

    Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility

  20. On the Use of Self-Assembling Block Copolymers to Toughen A Model Epoxy

    NASA Astrophysics Data System (ADS)

    Chen, Yilin

    Block copolymers have been receiving considerable attention in toughening epoxy due to their ability to form a wide variety of nanostructures. This study focuses on using both triblock and diblock copolymers to improve the fracture toughness of an aromatic-amine cured epoxy system. The curing system consisted of 1,3- phenylenediamine (mPDA) as curing agent and aniline as a chain extender. Three triblock copolymers and three diblock copolymers were incorporated in the same lightly crosslinked model epoxy system, which was chosen to mimic an underfill material in flip-chip packaging for the microelectronics industry. In this research, rubber particles were formed in situ using self-assembling block copolymers. Mechanical, thermal and microscopic studies were conducted with the main goal to study the relationship between the block parameters and the final morphologies and their effects on static and dynamic mechanical properties of the toughened resin, especially fracture toughness. In these block-copolymer-modified epoxies, spherical micelles and wormlike micelles were obtained by varying block lengths, molecular weight, polarities and compositions. It was found that miscibility of the epoxy-miscible block played a crucial role in the formation of different types of morphologies. At a low loading level, diblock copolymers were able to toughen the model epoxy as effectively as triblock copolymers. The fracture toughness was improved to almost three times with respect to that of the neat resin with addition of 10 phr AM*-27. At the same time, other mechanical properties, such as yield strength and modulus, were well retained. Incorporation of block copolymers did not have a significant effect on glass transition temperature but caused an increase in coefficient of thermal expansion (CTE) of the modified epoxy. Particle cavitation and matrix void growth were proved to be the toughening mechanisms for SBM-Modified epoxies. However, these typical toughening mechanisms for

  1. Thermal rheological analysis of cure process of epoxy prepreg

    NASA Astrophysics Data System (ADS)

    Sun, Liangfeng

    2002-01-01

    The cure process of epoxy prepreg used as composite pipe joints was studied by means of differential scanning calorimetry (DSC), Bohlin Rheometer and other techniques. Isothermal DSC measurements were conducted between 110 and 220°C, at 10°C intervals. The results show that the complete cure reaction could be achieved at 220°C. The isothermal cure process was simulated with the four-parameter autocatalytic model. Except in the late stage of cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into the model. The modified model greatly improved the predicated data at the late stage of cure reaction. The dynamic cure process was different from the isothermal cure process in that it is composed of two cure reactions. For dynamic cure process, a three-parameter autocatalytic model was used. The parameters in the model were determined by two methods. One was based on Kissinger and Ozawa approach. The whole curing process was modeled with two reactions. Another method was based on Borchardt and Daniels kinetic approach with whole curing process was modeled with one reaction. The fitting results by first and second method agreed well with experimental value in the late and early cure stage, separately. Rheological properties of epoxy prepreg are closely related to the cure process. With the development of cure reaction, gelation occurs and epoxy prepreg becomes difficult to process. As temperature increases, the gel time decreases. Viscosity profiles were described by different models. Except the first and nth order viscosity models, new viscosity models were proposed. The proposed new viscosity models are better than the old models for both isothermal and dynamic cure processes. To graphically represent the phase changes of the cure process, the isothermal cure diagrams of time-temperature-transformation (TTT) and conversion

  2. Mechanical and thermal properties of nanoparticle filled epoxy nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhao, Su

    2007-12-01

    One of the potential advantages of nanoparticle filled thermosets is the unique combination of mechanical properties that can be obtained. There have been several reports of improved ductility and toughness in brittle thermoset polymers due to the addition of equiaxed nanoparticles. The mechanisms leading to these improvements, however, are poorly understood. In the present study, a model system of nanoscale alumina filled bisphenol A based epoxy with two interface conditions was used to highlight the mechanisms leading to significant improvements in ductility, toughness, modulus and fatigue crack propagation resistance. It was found that the interfacial condition is critical to controlling the mechanical properties of the nanocomposites. Well-bonded APTES-Al 2O3 (3-aminopropyltriethoxysilane treated alumina) nanoparticle filled epoxy nanocomposites showed significant improvements in tensile ductility (max 39%), fracture toughness (max 26%) and fatigue crack propagation resistance, while exhibiting an increase in modulus and maintained strength. Poorly-bonded NT-Al2O3 (non-treated) nanoparticle filled epoxy nanocomposites only showed improvements in fatigue crack propagation resistance and modulus. Fracture morphology and theoretical predictions were used to study the mechanisms. The key mechanism, that significantly improved the ductility or tensile toughness of the treated nanocomposites and distinguished the treated nanocomposites from the untreated nanocomposites, is crack deflection. Crack deflection occurred much more for the well-bonded nanocomposites due to the stronger particle/matrix adhesion. Furthermore, it was found that crack deflection, interfacial debonding and particle pull-out were critical for composites with a weak interface, but that a stronger interface lead to additional mechanisms of further crack deflection, plastic deformation, microcracking and as a result a further improvement in mechanical properties. In addition, higher thermal

  3. NMR investigation of non-brominated and brominated epoxy ester prepolymers

    NASA Astrophysics Data System (ADS)

    Žigon, M.; Osredkar, U.; Šebenik, A.

    1992-03-01

    1H, 13C and two-dimensional NMR spectroscopy has been used to investigate the structure of epoxy ester prepolymers, based on non-brominated DGEBA-type or brominated DGETBBA-type epoxy resins, and on an oligomeric carboxylic acid. In the presence of a quaternary phosphonium salt, besides diglycidylether of bisphenol A (DGEBA) or diglycidylether of tetrabromobisphenol A (DGETBBA) and their higher oligomers, monoesters with characteristic R-CH 2-CH(OH)-CH 2-OCOR' groups were detected in prevailing quantities. In dependence of the epoxy-carboxy ratio, isomeric monoesters with hydroxymethyl groups, diesters and diols might also be present.

  4. The Electrical Properties for Phenolic Isocyanate-Modified Bisphenol-Based Epoxy Resins Comprising Benzoate Group.

    PubMed

    Lee, Eun Yong; Chae, Il Seok; Park, Dongkyung; Suh, Hongsuk; Kang, Sang Wook

    2016-03-01

    Epoxy resin has been required to have a low dielectric constant (D(k)), low dissipation factor (Df), low coefficient of thermal expansion (CTE), low water absorption, high mechanical, and high adhesion properties for various applications. A series of novel phenolic isocyanate-modified bisphenol-based epoxy resins comprising benzoate group were prepared for practical electronic packaging applications. The developed epoxy resins showed highly reduced dielectric constants (D(k)-3.00 at 1 GHz) and low dissipation values (Df-0.014 at 1 GHz) as well as enhanced thermal properties.

  5. Dielectric and microwave attenuation properties of graphene nanoplatelet–epoxy composites

    SciTech Connect

    Wang, Zhou; Luo, Jia; Zhao, Guang–Lin

    2014-01-15

    Graphene nanoplatelet (GNP)–epoxy composites were fabricated for the investigation of the dielectric permittivity and microwave absorption in a frequency range from 8 to 20 GHz. The intrinsically conductive GNP particles and polarized interfacial centers in the composites contribute to the microwave absorption. A minimum reflection loss of −14.5 dB at 18.9 GHz is observed for the GNP–epoxy composites with 15 wt. % GNP loading, which is mainly attributed to electric conductivity and the charge multipoles at the polarized interfaces in the GNP–epoxy composites.

  6. Acceleration of the Epoxy Resin-Dicyandiamide Cure Cycle by Trisubstituted Ureas.

    DTIC Science & Technology

    1981-06-01

    EPOXY RESIN- DICYANDIAMIDE CURE CYCLE BY TRISUBSTITUTED UREAS BERNARD R. LaLIBERTE, ROBERT E. SACHER, and JOSEPH BORNSTEIN POLYMER RESEARCH DIVISION...OEE ACCEERAIONOF THE EPOXY RESIN- DICYANDIAMIDE Finale t &EYCEBY YYISUBSTITUTED IJRtAS , PERPlIOOINCG EPORT NUER 7’-A~t!Q"aLS CONTRACT OR GRANT NUMBER(s...N’,N’-dimethylurea, or Diuron, N-(3,4-dichlorophenyl)-N’,Nl-dimethylurea, to epoxy resin- dicyandiamide mixtures significantly decreases the

  7. Preparation and Property Study of Graphene Oxide Reinforced Epoxy Resin Insulation Nanocomposites with High Heat Conductivity

    NASA Astrophysics Data System (ADS)

    Shan, Xinran; Liu, Yongchang; Wu, Zhixiong; Liu, Huiming; Zhang, Zhong; Huang, Rongjin; Huang, Chuanjun; Liu, Zheng; Li, Laifeng

    2017-02-01

    In this paper, graphene oxide reinforced epoxy resin nanocomposites were successfully prepared. Compared with unmodified epoxy resin, the heat conductivity of the graphene oxide reinforced epoxy resin nanocomposites had been improved while keeping the insulation performance. The tensile strength was investigated at both room temperature (300 K) and liquid nitrogen temperature (77 K). And the fracture surfaces were examined by scanning electron microscopy (SEM). Results showed that the materials had excellent mechanical properties, which could be advantages for the applications as insulating layer in low temperature superconducting magnets.

  8. Fracture toughness of the sidewall fluorinated carbon nanotube-epoxy interface

    SciTech Connect

    Ganesan, Yogeeswaran; Peng, Cheng; Zhang, Jiangnan; Cate, Avery; Lou, Jun E-mail: jlou@rice.edu; Salahshoor, Hossein; Rahbar, Nima E-mail: jlou@rice.edu; Khabashesku, Valery

    2014-06-14

    The effects of carbon nanotube (CNT) sidewall fluorination on the interface toughness of the CNT epoxy interface have been comprehensively investigated. Nanoscale quantitative single-CNT pull-out experiments have been conducted on individual fluorinated CNTs embedded in an epoxy matrix, in situ, within a scanning electron microscope (SEM) using an InSEM{sup ®} nanoindenter assisted micro-device. Equations that were derived using a continuum fracture mechanics model have been applied to compute the interfacial fracture energy values for the system. The interfacial fracture energy values have also been independently computed by modeling the fluorinated graphene-epoxy interface using molecular dynamics simulations and adhesion mechanisms have been proposed.

  9. Photocured epoxy/graphene nanocomposites with enhanced water vapor barrier properties

    NASA Astrophysics Data System (ADS)

    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.

  10. Three-phase percolative silver-BaTiO3-epoxy nanocomposites with high dielectric constants

    SciTech Connect

    Qi, Lai; Lee, Burtrand I.; Samuels, William D.; Exarhos, Gregory J.; Parker, Sam G.

    2006-08-01

    A three-phase epoxy-based composite with randomly distributed Ag nanoparticles and BaTiO3 particles was synthesized in this work. By integrating Ag nanoparticles into the epoxy resin, the dielectric properties of the resin is significantly enhanced, which provides an ideal host for further mixing with BaTiO3 to prepare high-dielectric-constant polymer-based dielectrics. The devices that adopt these composites demonstrate high relative dielectric constants (?r ? 450) at room temperature, which is 110 times higher than that of the epoxy matrix. These nanocomposites were found with potential to be applied in the embedded capacitor applications.

  11. Thermal Evaluation of Scorched Graphite-Epoxy Panels by Infrared Scanning

    PubMed Central

    Slifka, A. J.; Hall, T.; Boltz, E. S.

    2003-01-01

    A simple measurement system is described for evaluating damage to graphite-epoxy panels, such as those used in high-performance aircraft. The system uses a heating laser and infrared imaging system to measure thermal performance. Thermal conductivity or diffusivity is a sensitive indicator of damage in materials, allowing this thermal measurement to show various degrees of damage in graphite-epoxy composites. Our measurements track well with heat-flux damage to graphite epoxy panels. This measurement system, including analysis software, could easily be used in the field, such as on the deck of an aircraft carrier or at remote air strips. PMID:27413602

  12. Magnesium compounds

    USGS Publications Warehouse

    Kramer, D.A.

    2012-01-01

    Seawater and natural brines accounted for about 57 percent of magnesium compounds produced in the United States in 2011. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties LLC from well brines in Michigan. Caustic-calcined magnesia was recovered from seawater by Premier Magnesia LLC in Florida, from well brines in Michigan by Martin Marietta and from magnesite in Nevada by Premier Magnesia. Intrepid Potash Wendover LLC and Great Salt Lake Minerals Corp. recovered magnesium chloride brines from the Great Salt Lake in Utah. Magnesium hydroxide was produced from seawater by SPI Pharma Inc. in Delaware and Premier Magnesia in Florida, and by Martin Marietta from its brine operation in Michigan.

  13. Bismaleimide compounds

    DOEpatents

    Adams, Johnnie E.; Jamieson, Donald R.

    1986-01-14

    Bismaleimides of the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, C1 or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the alkylene bridging group, optionally, is substituted by 1-3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  14. Bismaleimide compounds

    DOEpatents

    Adams, J.E.; Jamieson, D.R.

    1986-01-14

    Bismaleimides of the formula shown in the diagram wherein R[sub 1] and R[sub 2] each independently is H, C[sub 1-4]-alkyl, C[sub 1-4]-alkoxy, Cl or Br, or R[sub 1] and R[sub 2] together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R[sub 1] and R[sub 2] are not t-butyl or t-butoxy; X is O, S or Se; n is 1--3; and the alkylene bridging group, optionally, is substituted by 1--3 methyl groups or by fluorine, form polybismaleimide resins which have valuable physical properties. Uniquely, these compounds permit extended cure times, i.e., they remain fluid for a time sufficient to permit the formation of a homogeneous melt prior to curing.

  15. Glass Reinforcement of Various Epoxy Resins-Polyurea Systems

    NASA Astrophysics Data System (ADS)

    Joshi, Medha; Jauhari, Smita

    2012-07-01

    Polyureas (PUs) were prepared by the polycondensation reaction of disperse dyes containing -NH2 group and toluene 2, 4-diisocyanate. The disperse dyes have been prepared by coupling of various 2-diazobenzothiazoles with 1,3-benzenediamine. All the PUs were characterized by elemental analysis, spectral studies, number average molecular weight ( {overline{{Mn}} } ), and thermogravimetry. Further reaction of PUs was carried out with an epoxy resin (i.e., DGEBA). The curing study of prepared resins was monitored by differential scanning calorimeter (DSC). Based on DSC, thermograms glass fiber-reinforced composites have been laminated and characterized by chemical, mechanical, and electrical properties. The unreinforced cured resins were subjected to thermogravimetric analysis (TGA). The laminated composites showed excellent resistance properties against chemicals and good mechanical and electrical properties.

  16. Evaluation of failure criterion for graphite/epoxy fabric laminates

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Wharram, G. E.

    1985-01-01

    The development and application of the tensor polynomial failure criterion for composite laminate analysis is described. Emphasis is given to the fabrication and testing of Narmco Rigidite 5208-WT300, a plain weave fabric of Thornel 300 Graphite fibers impregnated with Narmco 5208 Resin. The quadratic-failure criterion with F sub 12=0 provides accurate estimates of failure stresses for the graphite/epoxy investigated. The cubic failure criterion was recast into an operationally easier form, providing design curves that can be applied to laminates fabricated from orthotropic woven fabric prepregs. In the form presented, no interaction strength tests are required, although recourse to the quadratic model and the principal strength parameters is necessary. However, insufficient test data exist at present to generalize this approach for all prepreg constructions, and its use must be restricted to the generic materials and configurations investigated to date.

  17. Warping of unsymmetric cross-ply graphite/epoxy laminates

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.

    1981-01-01

    Warping in unsymmetric graphite/epoxy laminates was studied with particular attention given to the change of residual stresses resulting from long term environmental exposure. Square, cured prepreg sheets were measured for edge deflection with a cathetometer, then quartered and remeasured. Two postcuring durations were then used, 7.5 and one hr at 177 C; varying cooldown rates after curing were used for other samples, and one set was stored in vacuum at 75 C. Maximum deflections and weight changes were measured periodically at room temperature. Average curvatures, the effect of postcure, and the effect of long-term exposure were determined. Larger panels exhibited cylindrical warping and smaller panels underwent anticlastic warping. The deflections were related to weight changes, i.e. moisture absorption, and the lower the moisture content, the higher the deflection. Relaxation of residual stresses at 75 C was neglibible after 220 days.

  18. Influence of Impact Damage on Carbon-Epoxy Stiffener Crippling

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    2010-01-01

    NASA, the Air Force Research Laboratory and The Boeing Company have worked to develop new low-cost, light-weight composite structures for aircraft. A Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept has been developed which offers advantages over traditional metallic structure. In this concept a stitched carbon-epoxy material system has been developed with the potential for reducing the weight and cost of transport aircraft structure by eliminating fasteners, thereby reducing part count and labor. By adding unidirectional carbon rods to the top of stiffeners, the panel becomes more structurally efficient. This combination produces a more damage tolerant design. This document describes the results of experimentation on PRSEUS specimens loaded in unidirectional compression subjected to impact damage and loaded in fatigue and to failure. A comparison with analytical predictions for pristine and damaged specimens is included.

  19. RADIATION EFFECTS ON EPOXY/CARBON-FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-01-11

    Piping in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) must withstand the stresses involved during an unlikely but potential deflagration event. One method proposed for protection and reinforcement of piping during such an event is the use of a carbon fiber-reinforced epoxy composite (Diamond-Wrap{reg_sign}). In the DWPF, this reinforcement composite product would be required to maintain its safety function for a 20-year service life. This product has been ASME-approved (nuclear code case 589) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. However, its radiation resistance properties have not been evaluated. This report documents initial radiation resistance testing of the product and microstructural effects. Additional testing is recommended to evaluate radiation effects on specific properties such as burst strength, chemical resistance/weeping and for service life prediction in critical applications.

  20. Iosipescu shear properties of graphite fabric/epoxy composite laminates

    NASA Technical Reports Server (NTRS)

    Walrath, D. E.; Adams, D. F.

    1985-01-01

    The Iosipescu shear test method is used to measure the in-plane and interlaminar shear properties of four T300 graphite fabric/934 epoxy composite materials. Different weave geometries tested include an Oxford weave, a 5-harness satin weave, an 8-harness satin weave, and a plain weave with auxiliary warp yarns. Both orthogonal and quasi-isotropic layup laminates were tested. In-plane and interlaminar shear properties are obtained for laminates of all four fabric types. Overall, little difference in shear properties attributable to the fabric weave pattern is observed. The auxiliary warp material is significantly weaker and less stiff in interlaminar shear parallel to its fill direction. A conventional strain gage extensometer is modified to measure shear strains for use with the Iosipescu shear test. While preliminary results are encouraging, several design iterations failed to produce a reliable shear transducer prototype. Strain gages are still the most reliable shear strain transducers for use with this test method.

  1. Shelf life determination of an epoxy resin by accelerated aging

    SciTech Connect

    Smith, H.M.

    1983-11-01

    The objectives of the study reported were to first define the rate and mode of degradation of an epoxy resin at two storage conditions, 4.4/sup 0/C and 25/sup 0/C, by means of a thermally accelerated aging experiment. Then, samples which had been aged the equivalent of at least 10 years at each storage condition would be tested for conformance to the material specifications. The study's results demonstrate that the commercial resin could be acquired and stored for the required 10 to 11 years without concern over degradation. The expected changes at the two storage temperatures have been defined. Aged resin samples are shown to yield an acceptable product. Sufficient data exist to predict the changes in viscosity and epoxide equivalent of the resin at any other storage temperature of interest. (LEW)

  2. Thermally induced twist in graphite-epoxy tubes

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Rousseau, C. Q.; Tompkins, S. S.

    1988-01-01

    This paper discusses an analytical and experimental study to investigate the thermally induced twist in laminated angle-ply graphite-epoxy tubes. Attention is focused on balanced laminates which, contrary to intuition, exhibit twist when the temperature is changed. The twisting is due to the fact that a lamina with ( a + phi) orientation and a lamina with (a - phi) orientation must be at slightly different radial positions in the twist. The lamina with the greater radial position determines the sense of the twist. Classical lamination theory does not predict this phenomenon, and so as more sophisticated theory must be employed. This paper outlines such as theory, which is based on an generalized plane-deformation elasticity analysis, and presents experimental data to confirm the predictions of the theory. A brief description of the experimental apparatus and procedure used to measure twist is presented.

  3. Hygrothermal damage mechanisms in graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Crossman, F. W.; Mauri, R. E.; Warren, W. J.

    1979-01-01

    T300/5209 and T300/5208 graphite epoxy laminates were studied experimentally and analytically in order to: (1) determine the coupling between applied stress, internal residual stress, and moisture sorption kinetics; (2) examine the microscopic damage mechanisms due to hygrothermal cycling; (3) evaluate the effect of absorbed moisture and hygrothermal cycling on inplane shear response; (4) determine the permanent loss of interfacial bond strength after moisture absorption and drying; and (5) evaluate the three dimensional stress state in laminates under a combination of hygroscopic, thermal, and mechanical loads. Specimens were conditioned to equilibrium moisture content under steady exposure to 55% or 95% RH at 70 C or 93 C. Some specimens were tested subsequent to moisture conditioning and 100 cycles between -54 C and either 70 C or 93 C.

  4. Experiments on stiffened conical shell structures using cast epoxy models

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Davis, R. C.

    1973-01-01

    Description of a casting technique for fabricating high-quality plastic structural models, and review of results regarding the use of such specimens to parametrically study the effect of base ring stiffness on the critical buckling pressure of a ring-stiffened conical shell. The fabrication technique involves machining a metal mold to the desired configuration and vacuum-drawing the plastic material into the mold. A room-temperature curing translucent thermoset epoxy was the casting material selected. A shell of revolution computer program which employs a nonlinear axisymmetric prebuckling strain field to obtain a bifurcation buckling solution was used to guide the selection of congifurations tested. The shell experimentally exhibited asymmetric collapse behavior, and the ultimate load was considerably higher than the analytical bifurcation prediction. The asymmetric buckling mode shape, however, initially appeared at a pressure near the analysis bifurcation solution.

  5. Impact behavior of filament wound graphite/epoxy fan blades

    NASA Technical Reports Server (NTRS)

    Bowles, K. J.

    1978-01-01

    The fabrication and impact tests of graphite/epoxy filament wound fan blades are discussed. Blades which were spin tested at tip speeds up to 305 meters per second retained their structural integrity. Two blades were each impacted with a 454 gram slice of a 908 gram simulated bird at a tip speed of 263 meters per second and impact angles of 22 and 32 deg. The impact tests were recorded with high-speed movie film. The blade which was impacted at 22 deg sustained some root delamination but remained intact. The 32 deg impact separated the blade from the root. No local damage other than leading edge debonding was observed for either blade. Results of a failure mode analysis are also discussed.

  6. Graphite/epoxy composite stiffened panel fabrication development

    NASA Technical Reports Server (NTRS)

    Palmer, R. J.

    1984-01-01

    This report describes the manufacturing development procedures used to fabricate a series of carbon/epoxy panels with integrally molded stiffeners. Panel size was started at 6 inches by 18 inches and one stiffener and increased to 30 inches by 60 inches and six integral stiffeners. Stiffener concepts were optimized for minimum weight (or mass) to carry stress levels from 1500 lbs/inch to 25,000 lbs/inch compression load. Designs were created and manufactured with a stiffener configuration of integrally molded hat, J, I, sine wave I, solid blade, and honeycomb blade shapes. Successful and unsuccessful detail methods of tooling, lay-up methods, and bagging methods are documented. Recommendations are made for the best state-of-the-art manufacturing technique developed for type of stiffener construction.

  7. Thermal modeling of carbon-epoxy laminates in fire environments.

    SciTech Connect

    McGurn, Matthew T. , Buffalo, NY); DesJardin, Paul Edward , Buffalo, NY); Dodd, Amanda B.

    2010-10-01

    A thermal model is developed for the response of carbon-epoxy composite laminates in fire environments. The model is based on a porous media description that includes the effects of gas transport within the laminate along with swelling. Model comparisons are conducted against the data from Quintere et al. Simulations are conducted for both coupon level and intermediate scale one-sided heating tests. Comparisons of the heat release rate (HRR) as well as the final products (mass fractions, volume percentages, porosity, etc.) are conducted. Overall, the agreement between available the data and model is excellent considering the simplified approximations to account for flame heat flux. A sensitivity study using a newly developed swelling model shows the importance of accounting for laminate expansion for the prediction of burnout. Excellent agreement is observed between the model and data of the final product composition that includes porosity, mass fractions and volume expansion ratio.

  8. Reactive block copolymer vesicles with an epoxy wall.

    PubMed

    Zhu, Hui; Liu, Qingchun; Chen, Yongming

    2007-01-16

    Recently, block copolymer vesicles have attracted considerable attention because of their properties in encapsulation and release. To explore their applications in biorelated fields, functionalization of the polymer vesicle is necessary. Herein, a reactive unilamellar vesicle is reported by self-assembly of poly(ethylene oxide)-block-poly(glycidyl methacrylate) copolymer (PEO-b-PGMA) in solution. When water was added into the PEO-b-PGMA solution in THF, unilamellar vesicles were produced. If hydrophobic primary amine additives, such as hexamethylenediamine (HDA) and dodecylamine (DA), were introduced during block copolymer assembling, the vesicular morphology remained unchanged; instead, the amines reacted with the epoxys and the vesicles were fixed by cross-linking. Furthermore, when 3-aminopropyl trimethoxysilane (APS) was applied, the organic/inorganic hybrid vesicles were obtained, which were stable against the solvent change. Therefore, this research not only supplies a new way to fix the vesicular morphology but also a reactive vesicle scaffold for introducing functional species.

  9. Effect of cellulose nanowhiskers functionalization with polyaniline for epoxy coatings

    NASA Astrophysics Data System (ADS)

    Borsoi, C.; Zattera, A. J.; Ferreira, C. A.

    2016-02-01

    Functionalization of cellulose nanowhiskers (CNW) was performed by means of chemical synthesis involving polymerization of polyaniline in emeraldine salt form (PAni SE) in the presence of CNW. Thermal, chemical and morphological samples properties were evaluated. Polymeric coatings were obtained with epoxy, aminopropyltriethoxysilane (APS), CNW and CNW/PAni SE applied on carbon steel with a conversion coating of zirconia (Zr) and the mechanical properties were evaluated. With regard to CNW functionalization the sample was encapsulated with PAni SE as observed by FTIR and morphologic analysis, with decreased thermal stability. Regarding the mechanical properties of CNW and CNW/PAni SE polymeric coatings, improvements in flexibility and hardness properties using the APS and Zr layer were observed. The adherence of polymer coatings improved by the incorporation of CNW and CNW/PAni SE. Through morphological analysis it was observed that CNW shows good dispersion in the polymer matrix without agglomerates formation.

  10. Buckling of a fiber bundle embedded in epoxy

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Sohi, M. M.

    1986-01-01

    Buckling of a fiber bundle embedded in epoxy resin was studied to gain insight into compressive failure mechanisms in unidirectional composites. The fibers used were E-glass, T300 graphite, T700 graphite, and P75 graphite. These fibers were combined with two different resins: Epon 815/V140 and Epon 828/Z. In both resins the failure mode of the bundle was found to be microbuckling of fibers for the first three types of fibers; however, the high-modulus P75 fibers failed in shear without any sign of microbuckling. The strains at which microbuckling occurred were higher than the compressive failure strains of the corresponding unidirectional composites. In the soft resin, Epon 815/V140, fibers buckled at lower strains than in the stiff resin, Epon 828/Z. The buckling strains and the segment lengths followed the trends predicted for a single filament embedded in an infinite matrix.

  11. The mechanical behavior of an alumina carbon/epoxy laminate

    SciTech Connect

    Sherman, D.; Leckie, F.A.; Lemaitre, J.

    1995-12-01

    An experimental study has been made of a laminate consisting of monolithic thin alumina plates alternating with unidirectional carbon/epoxy (C/E) prepreg tapes. The main advantages of this system over the traditional means of reinforcing ceramics, are the avoidance of large flaws due to processing, which occur in fiber reinforced brittle matrix composites, and the nearly isotropic behavior under biaxial loading. In addition, the multiple fracture mechanism occurring in the system gives rise to pseudo ductile behavior and enhanced strain energy dissipation.The mechanical behavior of the laminate is explored. The effects of the number of layers, volume fraction and transverse properties are also investigated. The loss of stiffness with increase of the applied strain is estimated using a simple shear lag theory, which includes the plastic behavior of the interface.

  12. Neutron shielding material based on colemanite and epoxy resin.

    PubMed

    Okuno, Koichi

    2005-01-01

    In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or upgradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use.

  13. Photoinitiation study of Irgacure 784 in an epoxy resin photopolymer

    SciTech Connect

    Sabol, Dusan; Gleeson, Michael R.; Liu, Shui; Sheridan, John T.

    2010-03-15

    A deeper understanding of the processes, which occur during free radical photopolymerization, is necessary in order to develop a fully comprehensive model, which represents their behavior during exposure. One of these processes is photoinitiation, whereby a photon is absorbed by a photosensitizer producing free radicals, which can initiate polymerization. These free radicals can also participate in polymer chain termination (primary termination), and it is therefore necessary to understand their generation in order to predict the temporally varying kinetic effects present during holographic grating formation. In this paper, a study of the photoinitiation mechanisms of Irgacure 784 photosensitizer, in an epoxy resin matrix, is presented. We report our experimental results and present a theoretical model to predict the physically observed behavior.

  14. Tensile stress-strain behavior of graphite/epoxy laminates

    NASA Technical Reports Server (NTRS)

    Garber, D. P.

    1982-01-01

    The tensile stress-strain behavior of a variety of graphite/epoxy laminates was examined. Longitudinal and transverse specimens from eleven different layups were monotonically loaded in tension to failure. Ultimate strength, ultimate strain, and strss-strain curves wee obtained from four replicate tests in each case. Polynominal equations were fitted by the method of least squares to the stress-strain data to determine average curves. Values of Young's modulus and Poisson's ratio, derived from polynomial coefficients, were compared with laminate analysis results. While the polynomials appeared to accurately fit the stress-strain data in most cases, the use of polynomial coefficients to calculate elastic moduli appeared to be of questionable value in cases involving sharp changes in the slope of the stress-strain data or extensive scatter.

  15. Ultrasonic detection of fatigue damage in glass-epoxy composites

    SciTech Connect

    Simpson, W.A. Jr.; McClung, R.W.

    1990-01-01

    Energy storage flywheels fabricated of S2 glass-epoxy composite were studied to determine the behavior of the ultrasonic properties as a function of strain history and to identify possible predictors of incipient failure. Tensile specimens of the flywheel material were loaded uniaxially, and the ultrasonic properties (i.e., the shear and longitudinal wave velocities and the attenuation) were measured as a function of strain. Finished flywheels were similarly tested at various stages during cyclic spin testing; in addition, the polar backscattering intensity as a function of fatigue cycle was recorded. The velocities are excellent indicators of the maximum strain incurred at each point of the flywheel, and the attenuation delineates the region in which the stress is high enough to initiate microcracking in the matrix.

  16. EPOXI Uplink Array Experiment of June 27, 2008

    NASA Astrophysics Data System (ADS)

    Vilnrotter, V.; Tsao, P. C.; Lee, D. K.; Cornish, T. P.; Paal, L.; Jamnejad, V.

    2008-08-01

    Uplink array technology is currently being developed for NASA's Deep Space Network (DSN) to provide greater range and data throughput for future NASA missions, including manned missions to Mars and exploratory missions to the outer planets, the Kuiper Belt, and beyond. The DSN uplink arrays employ N microwave antennas transmitting at 7.2 GHz (X-band) to produce signals that add coherently at the spacecraft, hence providing a power gain of N^2 over a single antenna. This gain can be traded off directly for an N^2 higher data rate at a given distance such as Mars, providing, for example, high-definition video broadcast from Earth to a future human mission, or it can provide a given data rate for commands and software uploads at a distance N times greater than would be possible with a single antenna. The uplink arraying concept has been recently demonstrated using the three operational 34-m antennas of the Apollo Complex at the Goldstone Deep Space Communications Complex in California, which transmitted arrayed signals to the EPOXI spacecraft (an acronym formed from EPOCh and DIXI: Extrasolar Planetary Observation and Characterization and Deep Impact Extended Investigation). Both two-element and three-element uplink arrays were configured, and the theoretical array gains of 6 dB and 9.5 dB, respectively, were demonstrated experimentally. This required initial phasing of the array elements, the generation of accurate frequency predicts to maintain phase from each antenna despite relative velocity components due to Earth rotation and spacecraft trajectory, and monitoring of the ground-system phase for possible drifts caused by thermal effects over the 16-km fiber-optic signal distribution network. This article provides a description of the equipment and techniques used to demonstrate the uplink arraying concept in a relevant operational environment. Data collected from the EPOXI spacecraft are also analyzed to verify array calibration, array gain, and system stability

  17. Ultrasonic analysis of Kevlar-epoxy filament wound structures

    NASA Astrophysics Data System (ADS)

    Brosey, W. D.

    1985-07-01

    Composite structures are often desirable for their strength and weight characteristics. Since composites are not as well characterized mechanically as metallic or ceramic structures, much work has been performed at the Oak Ridge Y-12 Plant to obtain that characterization and to develop methods of determining the mechanical properties of a composite nondestructively. Most of the work to date has been performed on nonenclosed structures. One notable exception has been the holographic evaluation of spherical Kevlar-epoxy composite pressure vessels. Several promising nondestructive evaluation techniques have been used to locate flaws and predict the integrity of the composite. Several of these include thermography, Moire interferometry, ultrasonic stress wave factor, ultrasonic C-scan image enhancement, radiography, and nuclear magnetic resonance. As a first step in this transfer and development of NDE techniques, known defects were placed within spherical Kevlar-epoxy, filament-wound test specimens to determine the extent to which they could be detected. These defects included Teflon shim-simulated delaminations, macrosphere-simulated voids, dry-band sets, variable tension, Kevlar 29 fiber instead of the higher strength Kevlar 40 fiber, and an alternate high-void-content winding pattern. Ultrasonic waveform analysis was performed in both the time and frequency domains to determine the detectability and locatability of structural flaws within the composite. Preparation has been made at Virginia Polytechnic Institute and State University and at the University of Delaware, to examine the specimens using various NDE techniques. This work is a compilation of interim project reports in partial fulfillment of the contracts between Virginia Polytechnic Institute and State University, the University of Delaware, and Y-12 Plant.

  18. Strength and failure behavior of stitched carbon/epoxy composites

    NASA Astrophysics Data System (ADS)

    Kamiya, Ryuta; Chou, Tsu-Wei

    2000-03-01

    This article presents a study of the effect of through-the-thickness stitching yarns upon the strength and failure behavior of multidirectionally reinforced composites. The in-plane yarns were placed in four directions (0,±45, 90) to form a quasi-isotropic preform, which had open spaces between adjacent yarns. These interyarn spaces allowed easy insertion of the through-the-thickness stitching yarns without significant damage of the in-plane fibers. Fiber volume fractions of over 54 pct were obtained by this method. The through-the-thickness yarn sizes used in this study were 2, 4, and 6 kilo-filament (kf). Non-stitched performs were also manufactured with the same fiber content and by the same procedure as the stiched preforms for the control experiments. All preforms were infiltrated with epoxy resin by the resin transfer molding (RTM) technique. In-plane tensile and compressive strength, interlaminar shear strength, and mode I fracture toughness of the carbon/epoxy composites were measured at three through-the-thickness yarn contents. Although the through-the-thickness yarns significantly enhanced the mode I fracture toughness, they tended to degrade the in-plane tensile and compressive strength. The failure process under interlaminar shear loading by double notch shear tests showed two distinct stages: the fiber-matrix interfacial failure followed by the breakage/debonding of the through-the-thickness yarns. The through-the-thickness yarns caused a reduction of the initial failure load in the first stage but could enhance the final failure load in the second stage. In composites with 6 kf through-the-thickness yarns, the final failure load could exceed the initial failure load. Scanning electron microscope (SEM) and optical microscopic examinations were also conducted for observing the failure mechanisms and fracture surfaces.

  19. Impact response of graphite/epoxy fabric structures

    NASA Technical Reports Server (NTRS)

    Lagace, Paul A.; Kraft, Michael J.

    1990-01-01

    The impact damage resistance and damage tolerance of graphite/epoxy fabric plate (coupon) and cylinder structures were investigated and compared in an analytical and experimental study. Hercules A370-5H/3501-6 five-harness satin weave cloth in a quasi-isotropic (0,45)(sub s) laminate configuration was utilized. Specimens were impacted with 12.7 mm diameter steel spheres at velocities ranging from 10 m/s to 100 m/s. Damage resistance of the specimens was determined through the use of dye penetrant enhanced x-radiography, sectioning, epoxy burnoff, and visual methods. Damage tolerance of the flat plate structures was assessed in a residual tensile test while damage tolerance of the cylinder structures was assessed via pressurization tests. Impacted fabric laminates exhibited matrix crushing, fiber breakage, delamination, and fiber bundle disbonds; the latter being a unique damage mode for fabric laminates. Plate delamination and bundle disbonding was found to be more extensive around the central core area of fiber damage in the coupon specimens than in the cylinder specimens which showed a cleaner damage area due to impact. Damage resistance and damage tolerance were predicted by utilizing a five-step analysis approach previously utilized for coupon configurations. Two of the five steps were adapted to account for the effects of the structural configuration of the pressurized cylinder. The damage resistance analysis provided good correlation to the fiber damage region of both the coupon and cylinder specimens. There was little difference in the size of this region in the two specimen types. However, the analysis was not able to predict the distribution of damage through-the-thickness. This was important in assessing the damage tolerance of the cylinders. The damage tolerance analysis was able to predict the residual tensile strength of the coupons. A general methodology to predict the impact damage resistance and damage tolerance of composite structures utilizing

  20. Damping Behavior of Alumina Epoxy Nano-Composites

    NASA Astrophysics Data System (ADS)

    Katiyar, Priyanka; Kumar, Anand

    2016-10-01

    Polymer nano composites, consisting of a polymer matrix with nanoparticle filler, have been predicted to be one of the most beneficial applications of nanotechnology. Addition of nano particulates to a polymer matrix enhances its performance by capitalizing on the nature and properties of the nano-scale fillers. The damping behavior of composites with nano structured phases is significantly different from that of micro structured materials. Viscoelastic homopolymer exhibit a high material damping response over a relatively narrow range of temperature and frequencies. In many practical situations, a polymeric structure is required to possess better strength and stiffness properties together with a reasonable damping behavior. Viscoelastic polymers show higher loss factor beyond the glassy region which comes with a significant drop in the specific modulus. Addition of nano alumina particles to epoxy leads to improved strength and stiffness properties with an increase in glass transition temperature while retaining its damping capability. Experimental investigations are carried out on composite beam specimen fabricated with different compositions of alumina nano particles in epoxy to evaluate loss factor, tan δ. Impact damping method is used for time response analysis. A single point Laser is used to record the transverse displacement of a point on the composite beam specimen. The experimental results are compared with theoretical estimation of loss factor using Voigt estimation. The effect of inter phase is included in theoretical estimation of loss factor. The result reveals that the study of interface properties is very important in deriving the overall loss factor of the composite since interface occupies a significant volume fraction in the composite.