Showing papers on "Epoxy published in 1976"

Fatigue Behavior of Composite Laminate

Abstract: The paper discusses a characterization of fatigue behavior of [0/±45/90]s glass/epoxy laminate in terms of the following parameters: static properties; S-N relationship; reliability; effect of thickness variation; damage initiation and growth; temperature increase; secant modulus change; effect of preloading on residual modulus and strength; and effect of ply failure on compression buckling strength. Some of the findings are the following. The primary failure process responsible for up to about 106 cycles of fatigue life is the wear-out followed by the chance failure. Change of secant modulus can be used as a measure of damage extent. Preloading to a high level has negligible effect on the residual tensile strength when the fatigue stress is low. However, ply failure and partial delamination result in a moderate loss of compression buckling strength.

Electromechanical Properties in the Composites of Epoxy Resin and PZT Ceramics

Abstract: The complex dielectric, elastic and piezoelectric constants were measured for the composites of epoxy resin and ferroelectric PZT ceramics at 10 Hz as a function of temperature, and the magnitudes and loss tangents of these constants were compared with the theoretical predictions. The piezoelectric constants for a two phase system with piezoelectric spherical inclusions were expressed in terms of the properties of the constituents by use of the known expressions of the dielectric and elastic constants. The observed values of the d-constant (electric displacement/stress) were about 3/4 of the predicted. In the local mode dispersion region of epoxy resin near -30°C, the g-constant (electric field/stress) showed a larger temperature variation than the theoretical prediction.

Effect of Temperature on the Adhesive Fracture Behavior of an Elastomer-Epoxy Resin

Abstract: The bulk and adhesive fracture behavior of a diglycidyl ether bisphenol-A epoxy modified with 15% carboxy-terminated butadiene acrylonitrile was determined as a function of temperature. The bulk fracture toughness increased sharply near the resin Tg in a manner similar to unmodified epoxy resins. The adhesive fracture energy exhibited a maximum with respect to bond thickness and this maximum broadened and shifted to larger bond thicknesses with increasing temperature. These results are discussed in terms of the size and stress condition of the crack tip deformation zone.

Dynamic Mechanical Behavior of Fiber-Reinforced Composites: Measurement and Analysis:

Abstract: This paper describes analytical and experimental efforts to find the internal damping and elastic stiffness of E-glass fiber-reinforced epoxy beams under flexural vibration. Stiffness and damping a...

Nodular structure in epoxy resins

Abstract: Nodular morphology is observed on free surfaces, fracture surfaces, and etched surfaces of epoxy resins of widely different cure and chemistry. The influence of high- and low-energy substrates on nodule size is illustrated. Fine structure or “dimples” exist on several individual nodules, and various states of agglomeration of nodules are depicted. The possible relations between nodular morphology and adhesion phenomena are discussed.

Buckling behavior and structural efficiency of open-section stiffened composite compression panels

Abstract: Several exploratory experiments with /- and blade-stiffened graphite/epoxy panels were conducted to obtain insight into how well experimental data could be correlated with analysis for the buckling behavior of opensection stiffened composite compression panels. Although some nonlinear behavior was observed during the experiments, adequate correlation with analysis was obtained to justify the use of linear, thin-plate buckling analysis in a minimum-weight design synthesis program for J- and blade configurations. Results from two design studies using this program are presented. In the first study the minimum weights of J- and blade-configurations for two different material systems (graphite/epoxy and aluminum) are determined subject to buckling and strength constraints for a wide range of the compressive load index. In the second study the minimum weights required for graphite/epoxy blade-stiffened panels to satisfy additional stiffness constraints typical of mediumsize commercial aircraft wing structures are determined. Both minimum-weight studies indicate that graphite/epoxy open-section stiffened panels can be designed so that weight savings of 30% to 50% are possible compared with the most efficient aluminum designs.

Improved staining procedures for semithin epoxy sections of plant tissues.

Abstract: Improved and reliable methods are described for staining semithin sections of plant materials fixed in glutaraldehyde-osmium and embedded in epoxy resins. One-micron sections are fixed to slides, s...

The thermal conductivity of epoxy-resin/metal-powder composite materials from 1.7 to 300K

Abstract: The thermal conductivity of composites made from epoxy-resin Epikote 828 with metal-powder fillers has been measured from 1.7 to 300K. The metals were Cu, Ag, Au, Al, Sn, Pb, stainless steel and bronze, and in almost all cases the particles were spherical or rounded. At 20K and above the thermal conductivity is independent of the particle size and is in good agreement with the relation of Meredith and Tobias (1960) (extension of Rayleigh's theory). Below 20K the thermal conductivity of the composite is lower than predicted by the theory especially for specimens containing smaller particles, and it can even be less than that of the unfilled resin. This is due to an acoustic mismatch of the phonons at the resin-particle interfaces. An effective particle conductivity which takes account of this mismatch can be computed, which when incorporated into the theory leads to reasonable agreement with experiment.

Caustic-resistant polymer coatings for glass

Abstract: Improved caustic-resistant coatings for glass which comprise (1) a primer layer consisting essentially of an epoxy resin containing a curing agent, e.g., polyamide, amine, etc., and an organofunctional silane either in a single layer or separate layers, in order on the glass, (a) organofunctional silane and (b) epoxy resin, and (2) a copolymer of alpha-olefins of the formula R--CH═CH 2 , where R is a radical of hydrogen or alkyl radicals having from 1 to 8 carbon atoms, and alpha, beta-ethylenically unsaturated carboxylic acids having from 3 to 8 carbon atoms, said copolymer having from 0 to 100 percent of the carboxylic acid groups ionized by neutralization with metal ions.

Measurement of the Elastic Moduli of Structural Adhesives by a Resonant Bar Technique

Abstract: A method of measuring the dynamic torsion and Young's moduli of a thin film of adhesive is described. The accuracy of the technique and its suitability for structural adhesives is discussed. Values of modulus obtained using this method are compared with values obtained from static and dynamic tests on bulk specimens of three epoxy adhesives.

Defect Property Relationships in Composite Materials.

Abstract: : This report describes the initial results of an investigation which has as its objectives the determination of the nature of damage in two graphite-epoxy (GEp) laminates under various combinations of loading as completely and precisely as possible, and the investigation of the corresponding mechanical property changes. The results include several new findings, the development of unique investigative methods, and substantial deviations from the predictions of common models. (Author)

Ultraviolet curable epoxy-polyester powder paints

Abstract: Powder paint coatings of this invention are particularly suitable for ultraviolet curing and comprise specific spatial arrangements of ethylenically unsaturated polymers. The polymers contain pendant double bond unsaturation in combination with an epoxy adduct spaced on the polymer chain from a polyester adduct. The powder paint is free of cold flow and can be applied electrostatically or physically to metal substrates, moderately heated to obtain desired flow out, and then cross-linked or cured by ultraviolet irradiation.

Liquid vinylidene-terminated polymers

Abstract: Liquid vinylidene (CH 2 ═C<) terminated polymers are prepared by the reaction of a (1) liquid polymer having a terminal functional group selected from the group consisting of carboxyl, hydroxyl, mercaptan, amine and epoxy and (2) a compound containing both an epoxy group ##STR1## and a vinylidene group. The reaction can be catalyzed using a base. The polymers cure readily to solid elastomers which are useful as sealants, caulks, potting compounds, coatings and the like.

Switching behaviour and DC electrical conductivity of epoxy-resin/metal-powder composites

Abstract: The DC electrical conductivity of composites made from Epikote 828 resin filled with Cu, Ag, Au, Al, Sn, Pb, bronze and stainless steel powders has been measured at room temperature. Apart from specimens containing Al and stainless steel, all others with a volume concentration of metal of about 20% of more showed switching behaviour. The normally high resistance of the composite was reduced to a few hundred ohms when a potential of about 100 V was applied across the sample and this low resistance was retained as the potential was reduced to zero. The high-resistance state could be recovered by passing a current of a few hundred mA through the sample.

Polyether diureide epoxy additives

Abstract: The adhesion properties of amine-cured epoxy resins are unexpectedly enhanced by addition of certain polyether amide additives. The adhesively superior epoxy resin composition comprises a vicinal polyepoxide, a curing amount of an amine curing agent, and an effective amount of a polyether diamide having terminal amido groups and a molecular weight of from about 2000 to about 3000.

Rubber-metal composite structures having improved resistance to corrosion

Abstract: Rubber-metal composite structures are provided wherein such structures comprise a metal substrate, at least a portion of at least one surface of such substrate is coated with a fused epoxy resin powder composition, and at least one elastomeric element, said elastomeric element being vulcanization bonded through an intermediate adhesive phase to at least a portion of the fused epoxy coating. Such composite structures exhibit improved resistance to corrosion.

Polyether urea epoxy additives

Abstract: The adhesion properties of amine-cured epoxy resins are unexpectedly enhanced by addition of certain amino terminated polyether ureylene additives. The adhesively superior epoxy resin composition comprises a vicinal polyepoxide, a curing amount of an amine curing agent, and an effective amount of a polyether ureylene having terminal amino groups and a molecular weight of from about 4000 to about 4500.

Aqueous epoxy resin paint composition

Abstract: An aqueous epoxy resin paint composition comprising an epoxy resin emulsion formed by emulsifying a bisphenol type epoxy resin or a mixture of a bisphenol type epoxy resin with an epoxy resin having a compatibility with said bisphenol type epoxy resin and a structure similar to that of said bisphenol type epoxy resin but being quite different therefrom in a part of the structure in water with a polyoxyethylene benzylated phenyl ether having an HLB value of at least 15, and a cutting agent and, if desired, a pigment and other additives.

Anti-soiling treatment for carpets and carpet yarns

Abstract: Soiling resistance and soil release of carpets are improved by coating the carpets or carpet yarns prior to carpet manufacture with a polymeric material containing either (A) a blend of a methacrylic acid emulsion copolymer and an epoxy resin or (B) a methacrylic acid emulsion copolymer having epoxy monomer units therein. The copolymer in either case contains 40-75% by weight methacrylic acid and the glass transition temperature of cured coatings of the polymeric material is at least 50° C.

Preparation of phenolic resin

Abstract: PURPOSE: To obtain a phenolic resin capable of lowering the softening point without degrading the properties of molded articles, by reacting a reaction product, prepared from a phenol and an aldehyde in the presence of an acid catalyst, with an epoxy alkyl compound. CONSTITUTION: One mole of a phenol is reacted with an aldehyde in the presence of an acid catalyst to give a reaction product, which is reacted with a monofunctional epoxy alkyl compound in an epoxy equivalent of 0.001W0.1 to form a phenolic resin having a low softening point. The softening point is adjusted by the amount of the epoxy alkyl compound. A tertiary amine, a quaternary ammonium salt, or an imidazole derivative as a catalyst may be added to the reaction mixture together with the epoxy alkyl compound to make the reaction proceed rapidly. COPYRIGHT: (C)1979,JPO&Japio

X-ray devices using epoxy resins strengthened with carbonic fibrous material

Abstract: Cast resins strengthened with carbonic fibrous material are used as the material for making parts which transmit X-rays and at the same time are subject to mechanical stresses.

Process for the preparation of powdered thermosetting compositions based on branched-chain carboxyl group-containing polyesters and epoxy compounds

Abstract: Process for the preparation of powdered thermosetting coating composition suitable for application as paint or varnish on electricity-conducting articles by powder spray methods and fluidized bed coating processes, which comprises: in a first stage, preparing a branched-chain hydroxyl group-containing polyester from at least one dicarboxylic organic acid, at least one polycarboxylic aromatic acid and at least one dihydric organic compound; in a second stage, esterifying the hydroxyl group-containing polyester thus obtained with an aromatic or hydroaromatic dicarboxylic acid to give a carboxyl group-containing polyester having an acid number which is substantially equal to the hydroxyl number of the hydroxyl group-containing polyester obtained in the first stage; and in a third stage, homogenously mixing the carboxyl group-containing polyester obtained in the second stage with an epoxy compound containing at least two epoxy groups, and optionally adding auxiliary substances conventionally used in the manufacture of powdered paints and varnishes; and powdered thermosetting compositions suitable as paint or varnish obtained by this process.

Compositions intended for the flameproofing of plastics

Abstract: Compositions based on red phosphorus and epoxy resin for flame proofing plastics without the release of toxic products during use. The compositions consist of a pulverulent mixture containing from 50 to 95% by weight of red phosphorus and from 5 to 50% by weight of compounds having epoxy groups in their chain.

Glass fiber sizing composition

Abstract: A glass fiber sizing composition comprising a phenolic epoxy resin; the reaction product of a partial ester of a polycarboxylic acid which contains one or more unesterified carboxyl groups with a compound containing more than one epoxy group; a glass fiber lubricant; sufficient emulsifiers to impart a homogeneous mixture; a saturated fatty triglyceride; a silane coupling agent and a major amount of water. Glass fibers sized in accordance with the invention exhibit excellent reinforcing characteristics.

Nonlinear analysis of laminated fibrous composites

Abstract: A computerized analysis of the nonlinear behavior of fibrous composite laminates including axial loading, thermal loading, temperature dependent properties, and edge effects is presented. Ramberg-Osgood approximations are used to represent lamina stress-strain behavior and percent retention curves are employed to model the variation of properties with temperature. Balanced, symmetric laminates comprised of either boron/epoxy, graphite/epoxy, or borsic-aluminum are analyzed using a quasi-three-dimensional finite element analysis. Results are presented for the interlaminar stress distributions in cross-ply, angle-ply, and more complex laminates. Nonlinear stress-strain curves for a variety of composite laminates in tension and compression are obtained and compared to other existing theories and experimental results.