Showing papers on "Epoxy published in 1977"

Effects of moisture and temperature on the tensile strength of composite materials

Abstract: The ultimate tensile strengths of Thornel 300/Fiberite 1034 graphite epoxy composites were measured with material temperatures ranging from 200 K to 422 K and moisture contents from 0% (dry) to 1.5...

Moisture Effects in Epoxy Matrix Composites

Abstract: : The effect of absorbed moisture on the mechanical properties of a neat epoxy resin and derived graphite/epoxy composites is investigated. Glass transition temperature and modulus as a function of moisture content and temperature is determined for both the neat resin and composite. In addition, elastic modulus for the neat resin, and strength and elastic moduli for unidirectional composites and quasi-isotropic laminates are determined as a function of absorbed moisture and temperature. A method for predicting moisture content and through-the-thickness profile for a laminate exposed to a constant humidity and temperature is discussed. Particular attention is also given to the details of environmental testing. Data indicates that absorbed moisture and temperature effects on the neat resin translate directly to matrix dominated properties of the composite and can lead to a change in failure mode, while filament dominated properties show very little environmental sensitivity. Results also indicate that resin glass transition temperature is a function of processing as well absorbed moisture.

Modified epoxy resins, processes for making and using same and substrates coated therewith

Abstract: Discloses a technique for modifying an epoxy resin by reacting with addition copolymerizable monomer in the presence of at least 3% of benzoyl peroxide at about 110° C. to 120° C., or the free radical initiating equivalent thereof. The reaction mixture obtained contains: (a) unreacted epoxy resin; (b) graft polymer; and (c) associatively formed but ungrafted addition polymer. The graft polymer is formed from the epoxy resin by the grafting of addition polymer onto aliphatic backbone carbons of the epoxy resin, such grafting being at carbons that have either one or two hydrogens bonded thereto in the ungrafted state. The process is useful for making polymer blends for coating compositions, and particularly, coatings for cans for foods and beverages, especially for beer. The coating compositions may be aqueous dispersions ready for spray application, or concentrate that can be made up readily into aqueous sprayable coating compositions. Solvent vehicles may also be used.

Photo-curing method for epoxy resin using group VIa onium salt

Abstract: Cationic polymerization of epoxy resin materials, such as epoxy monomers or prepolymers, can be achieved by use of certain radiation sensitive aromatic onium salts of Group VIa elements. Curable compositions are provided which can be used as sealants, coating compounds, encapsulants, etc.

Gelled water epoxy sand consolidation system

Abstract: Particular aqueous gels, epoxy resin compositions and optional additives such as diluents, retarders and accelerators are described which produce a practical composition and method for in situ sand consolidation and gravel packing by which a resin coated sand is positioned in a desired location and cured by an internal catalyst to form a porous permeable or plugged consolidated mass.

Curing of epoxide resins: Model reactions of curing with amines

Abstract: The reaction of tetrafunctional diamines and bifunctional amines with monoepoxy compounds was investigated by gel-permeation chromatography. At a stoichiometrically equivalent ratio of the functional groups or excess of amine, the consecutive reaction of the epoxide groups with the hydrogen atoms of the amino groups is the only reaction that is taking place; if epoxide is present in excess, the OH groups formed in the reaction are gradually added to the epoxide groups. The ratio of the rate constants of the reaction of the epoxy group with the hydrogen atoms of the primary and secondary amino group was calculated from the concentrations of the reaction products at various excess amounts of amines. The ratio is in good accord with the value calculated from the gel points and limiting stoichiometric ratios in the curing of diepoxides with diamines.

Kinetics of epoxy resin polymerization using differential scanning calorimetry

Abstract: The kinetic parameters of the polymerization of diglycidyl ether of bisphenol A with hexahydrophthalic anhydride and benzyldimethylamine as catalyst were determined using differential scanning calorimetry. The reaction was found to be first order with some variation with temperature, and the activation energy and natural log of the frequency factor were 25 kcal/mole and ∼25 sec−1, respectively. These results are discussed with respect to a steady-state mechanism of the polymerization and compared with results reported for other epoxide–anhydride reactions.

Void formation and electrical breakdown in epoxy resin

Abstract: The long term behaviour of epoxy resin subjected to high alternating electrical stress was studied using optical magnifications of up to 1500, a scanning electron microscope, and a high sensitivity discharge detector. The formation of voids in initially void-free specimens was investigated when voltages of duration between ten seconds and several thousand hours were applied using a pin-plane configuration. Defects in epoxy resins, mechanisms of their electrical aging, and their long term dielectric strength are discussed in relation to the phenomenon of void growth.

Method of coupling a protein to an epoxylated latex

Abstract: Proteins are coupled to polymer particles containing free epoxy groups in a latex. The polymer particles are about 0.15 to 1.5 micrometers in diameter, and have an inner core and an outer shell which contains the free epoxy groups. The coupled proteins are particularly useful in carrying out immunological tests.

Dielectric compositions comprising ethylene polymer stabilized against water treeing with epoxy containing organo silanes

Abstract: A dielectric composition comprising ethylene polymer and effective amounts, as a water treeing inhibitor, of at least one epoxy containing organo silane.

Analysis of Nonlinear Stress-Strain Behavior of Fiber-Reinf orced Composite Materials

Abstract: Fiber-reinforced composite materials generally exhibit nonlinear stress-strain behavior in at least one of the principal material directions. For example, boron/epoxy and graphite/epoxy have highly nonlinear shear behavior. Moreover, boron/aluminum has nonlinear behavior transverse to the fibers as well as a shear nonlinearity, and carbon/carbon has nonlinearities in all principal material directions. The Jones-Nelson strain energy based nonlinear mechanical property model is extended to treat all nonlinearities of fiber-reinfor ced composites. The basic model will converge only up to a specific strain energy value. That limitation is eased by using new extrapolations of the stress-strain curve and mechanical property - energy curve for strain energies above available stress-strain data. These extrapolations are necessary because the strain energies of biaxial loading exceed the strain energies of uniaxial loading under which the properties are defined and because the maximum strain energies under uniaxial loading are different in the various principal directions due to orthotropy. Strains predicted with the new material model correlate well with strains measured by Cole and Pipes in uniaxial off-axis loading of boron/epoxy and graphite/epoxy. The predicted strains are also close to strains predicted by Hahn and Tsai, who use a material model with a single (shear) nonlinearity. Our model can be used for the several nonlinearities of boron/aluminu m and carbon/carbon; therefore, it is more widely applicable than the Hahn and Tsai model.

Powder coating composition employing mixture of polyepoxide resin with modified polyester resin

Abstract: Thermosetting coating compositions for powder coating processes, having a good powder stability, comprise a mixture of 4-25 wt % of a polyepoxide resin, the average molecule of which contains at least two epoxy groups, and 75-96 wt % of a solid modified polyester resin having an acid number of 30-100 and softens in the range of 60° C.-130° C. The solid modified polyester resin is the reaction product of an anhydride of a polybasic, organic carboxylic acid and a polyester having a hydroxyl number of 15-50 derived from a dibasic aromatic carboxylic acid and a specific alcohol component.

Moisture Absorption and Desorption in Epoxy Composite Laminates

Abstract: Epoxy composite laminates absorb moisture from the atmosphere via a diffusion controlled process and undergo changes in both mechanical properties and dimensional shapes. This paper reviews the nature of moisture absorption by epoxy composites and the resultant effects upon the laminate.

Patch testing with low molecular oligomers of epoxy resins in humans.

Abstract: Thirty-four patients sensitive to epoxy resin were patch tested with oligomers of epoxy resin All reacted when tested with MW 340 oligomer Twenty-three were tested with MW624 and MW908 oligomers and seven with MW 1392 oligomer; none reacted Eight patients tested with commercial mixtures of epoxy resins with an average MW 1280 and MW 1850 reacted to these resin mixtures which contained the MW 340 oligomer The MW 340 oligomer seems to be the main ingredient responsible for contact allergy to epoxy resins in humans

Encapsulant compositions based on anhydride-hardened epoxy resins

Abstract: Epoxy molding compositions useful as semiconductor encapsulants, comprising (a) an epoxide compound; (b) as hardener, a polyanhydride of a maleic monomer and at least one alkyl styrene monomer or prepolymers of the polyanhydride and said epoxide compound; (c) a catalyst; (d) about 1 to 80 percent by weight of a silica filler; (e) about 1 to 80 percent by weight of an additional filler selected from the group consisting of calcined clay, antimony trioxide, antimony tetraoxide, calcium silicate, titanium dioxide, calcium carbonate, zinc oxide, magnesium oxide and mixtures thereof; (f) about 0.05 to 2 percent by weight of a silane coupling agent; and (g) about 0.01 to 2 percent by weight of a lubricant selected from the group consisting of carnauba wax, montanic acid ester wax, polyethylene wax, polytetrafluoroethylene wax and mixtures thereof.

Ethylene carbon monoxide copolymers containing epoxy side groups

Abstract: New and useful blends of thermosetting resins with copolymers of certain amounts of ethylene with another monomer copolymerizable therewith to provide solid but flexible polymers, and a third monomer containing epoxy side groups, and optionally carbon monoxide, are provided. These blends result in performance unattainable with the thermosetting resin alone in terms of flexibility, toughness, and adhesion. Such blends may be used, for example, to produce flexible, semirigid or rigid films, coatings, fibers, foams or molded articles.

Reaction products of non-cycloaliphatic epoxy resins and amine-terminated liquid polymers and process for preparation thereof

Abstract: Room-temperature-curable compositions can be prepared readily by mixing (A) 100 parts by weight of at least one non-cycloaliphatic epoxy resin and (B) from about 1 to about 1,000 parts by weight of at least one amine-terminated liquid polymer having a carbon-carbon backbone, (C) optionally, a chain extender or crosslinker and (D) optionally, a curing agent. The compositions are useful as castable elastomeric systems, as toughened structural plastics, as paints and coatings, as sealants and adhesives, and the like.

Thermal boundary resistance at metal-epoxy interfaces

Abstract: Measurements of the thermal impedance across copper-epoxy-copper sandwiches have been made over a temperature range of 0.05--10 K. The data are consistent with the suggestion that only low-frequency phonons contribute to thermal transport across the sandwich. As a result the apparent thermal boundary resistance at the interfaces may be a factor of 100 larger than calculated from the theory of Little. A similar behavior should be observed whenever an amorphous material is involved.

Haze-free transparent laminate having a plasticized polyvinyl acetal sheet

Abstract: A method for overcoming laminate failure in laminated windows containing adjacent layers of polycarbonate and plasticized polyvinyl acetal is disclosed. The method involves applying a protective adhesive means such as a film of a polyurethane or an epoxy resin to a major surface of at least one of the sheets, assembling the sheets with said film on an interfacial surface of the assembly, and laminating the assembly at high temperature and pressure. Also disclosed are various laminate configurations containing a plasticized polyvinyl acetal-polycarbonate interfacial surface treated according to the present invention. Such laminates are useful as substantially haze-free, transparent articles, such as windows for aircraft.

Curable epoxy-carboxylic acid adducts

Abstract: Adducts of epoxy compounds with amino-substituted aromatic carboxylic acids are described. These carboxyl-containing adducts may be cured with conventional epoxy curing agents or solubilized to prepare aqueous coating systems.

Metal acetylacetonate latent accelerators for an epoxy-styrene resin system

Abstract: An epoxy-styrene, solventless resin impregnating varnish, having an atmospheric catalyzed pot life at room temperature of at least 45 days, is made by mixing: (1) the product of the reaction of (a) 1 part of an epoxy resin mixture, comprising solid epoxy resin and liquid epoxy resin wherein the weight ratio of solid epoxy: liquid epoxy is between 1:1 to 1:10; with (b) between about 0.01 part to 0.06 part of maleic anhydride and (c) a catalyst; under such conditions that the epoxy diester formed has an acid number of between about 0.5 to 3.0; with (2) a coreactive vinyl monomer; and between about 0.0003 part to 0.004 part of a room temperature stabilizer (3) between about 0.3 part to 1.2 part of a polycarboxylic anhydride, which is soluble in the mixture of (1) and (2) and an amount of free radical catalyst that is effective to provide a catalytic effect on the impregnating varnish and to cure it at temperatures of over about 85° C., and with (4) between 0.0005 part to 0.005 part of a metal acetylacetonate, selected from the group consisting of chromium (III) acetylacetonate, manganese (III) acetylacetonate, ferric (iron III) acetylacetonate, zinc (II) acetylacetonate, aluminum (III) acetylacetonate, sodium (I) acetylacetonate, uranyl (VI) acetylacetonate, and mixtures thereof, acting as latent accelerator.

Low dissipation factor electrostatic epoxy wire coating powder

Abstract: A coating powder is made by hot melt mixing a composition of three diglycidyl ethers of bisphenol A, a pre-prepared epoxy ester, and a curing agent containing trimellitic anhydride. The composition is cooled to form a solid which is ground into a powder. Wire or other articles are coated with the coating powder in an electrostatic fluidized bed or with an electrostatic gun and the powder is cured.

Process for treating wells with viscous epoxy-resin-forming solutions

Abstract: A well treating process in which a granular mass is consolidated by contacting it with an epoxy resin-forming solution that precipitates a self-curing partially-cured resin, is improved by using such a solution that contains a viscosity-increasing amount of an otherwise substantially inert oil-soluble polymer

Polyether dihydroxyalkyl carbamate epoxy additive for epoxy resins

Abstract: The adhesion properties of amine-cured epoxy resins are unexpectedly enhanced by addition of certain di-hydroxyalkyl carbamate terminated polyether 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 dicarbamate having terminal hydroxyalkyl carbamate groups and a molecular weight of from about 2000 to about 3000.

Organometallic and organometalloid compounds as standards for microprobe analysis of epoxy resin embedded tissue.

Abstract: SUMMARY X-ray microanalysis of phosphorus, transition elements and heavy metals in biological tissue is frequently carried out on thin sections of specimens embedded in epoxy resin. A logical choice for the quantitive microprobe analysis of these specimens is a standard, consisting of a homogeneous solution of the elements of interest in the epoxy resin. Four kinds of compounds were found suitable for this purpose: (1) phenyl compounds containing group Vb elements, (2) cyclopentadienyl-derivatives, (3) a pentanedione derivative (acetylacetonate) and (4) complexes of metals with dialkyldithiocarbamates. In the latter case, the standard also contains sulphur. Standards for P, Sb (1) Mn, Fe (2) Ni (3) Cu, Zn, Cd, Hg, Pb, Bi (4) were prepared in Epon 812 or Spurr epoxy resin. The compounds were mixed with the resin (without accelerator) to which some propylene oxide may be added, and dissolved immediately or after short heating. The maximal concentration of metal was in the order of magnitude of several promilles to 1%. Solubility in the Spurr resin was better than in Epon 812. After addition of the accelerator, polymerization was carried out as usual. The compounds used are commercially available at low cost or can be easily prepared.

Organic coatings and paints having unique electrical properties

Abstract: Coatings with unique electrical properties, particularly for aluminum surfaces of aircraft structures, comprised of metallic fibers such as aluminum fibers, dispersed in an organic coating such as polyurethanes and epoxy primers. The metal fibers are sufficiently small in diameter and mass so as not to interfere with the required organic properties of the coating, but are of sufficient density to provide the required electrical conductivity.

The elastic properties in bulk and shear of a glass bead-reinforced epoxy resin composite

Abstract: A description is given of a new method for the measurement, using a single specimen, of the bulk, shear, and Young's moduli, and the thermal expansion coefficient of solid polymers. The method has been used to measure the bulk and shear moduli and expansion coefficient of a glass bead-filled epoxy resin over a particle concentration range of 0 to 40% volume. Results are compared with the theoretical predictions of Hill, Hashin and Shtrikman, Paul and others. In the glassy region the experimental data agree well with the Hashin and Shtrikman lower bound, but aboveT g the material is reinforced much more than suggested by these theories. Some evidence is given for a difference in glass transition temperature between filled and unfilled materials.