Showing papers on "Epoxy published in 1968"

Imidazole catalysis in the curing of epoxy resins

Abstract: The high catalytic activity of imidazoles and particularly of 2-ethyl-4-methylimidazole (EMI) for the curing of epoxy resins and the properties of the resulting resins prompted this study concerned with the nature of the curing reaction. Epon 828 epoxy resin and the model compound phenyl glycidyl ether were used as starting materials with EMI, 2-methylimidazole, and dimethylbenzylamine as catalysts. During the curing of the resin at 50°C., the decrease in the infrared absorption of the epoxy band with time is accompanied by a decrease in the intensity of the imine band of the imidazole moiety, indicating its reaction with the epoxy group and its incorporation into the resin. The measurement of the residual epoxy content after curing for 24 hr. at 50 and 140°C. showed that the imidazoles were not more efficient in completing the epoxy reaction than dimethylbenzylamine. In the experiments with phenyl glycidyl ether the rate of reaction of the epoxy group with EMI was faster than the rate of polymerization, proving that the imidazole becomes permanently attached to the polymer chain. These results also suggest that the true catalytic species is not EMI but some addition product thereof. In comparative rate measurements the compound formed from equimolar quantities of EMI and phenyl glycidyl ether was found to be an excellent catalyst. The NMR analysis of the 1:1 and 1:2 adducts of EMI and phenyl glycidyl ether has shown that the second mole of phenyl glycidyl ether reacts with the ring nitrogen in the 3 position and not with the hydroxyl group of the mono adduct. By forming the bis adduct in this way the imidazole molecule acts as a crosslinking agent and at the same time introduces an alkoxide ion which can initiate further polymerization. It is very likely that this crosslinking is the process that leads to the superior physical and chemical properties (high heat deflection temperature, resistance to chemicals and oxidation) of the resins prepared with imidazoles as catalysts.

Exchange packing element

Abstract: A packing for fluid treatment, either gaseous or liquid, for various surface contact effects such as drying of the fluid, heat exchange, ion exchange, molecular sieve separations and the like, wherein a laminated cellular structure of paper is coated throughout the cellular structure with a hard resin such as an epoxy resin in which such resin coating can be used alone for heat exchange purposes, or it can be further coated with dry solids to effect many of the fluid modifications.

Effect of Fillers and Voids on Compressive Yield of Epoxy Composites

Abstract: Two series of epoxy composites, filled and porous, were loaded in compression up to yield under several constant strain rates. Results indicate a linear relationship between yield stress and log strain rate, characterized by a constant slope for the different com positions, and almost linear dependence of yield stress on filler content. A simplified empirical formula was derived for the yield stress of filled composites as function of filler content and strain rate. Similar dependence was found for porous composites.The strain-rate dependence indicates non-Newtonian visco plastic behaviour obeying the corresponding Eyring equation. The filler content was found to have almost no effect on the activation volume terms, and its main effect is apparently with regard to the activation energy characteristics of the yielding process.

Flammability of epoxy resins

Abstract: Flammability determinations have been made for epoxy resin formulations. The oxygen index, defined as the volume fraction of oxygen in an oxygen/nitrogen atmosphere that is required just to sustain steady candlelike burning of a stick of the material, has been used as the measure of flammability. The formulations selected for study were those for which the chemical composition of the ingredients was known at least approximately and for which uniform cast slabs (1/8 in. thick) could be readily prepared. They covered a range of compositions of commercial interest. The results have been interpreted in terms of a proposed model for candlelike burning. Effects due to resin composition, cure conditions, fillers, and flame-retardant additives are discussed.

Epoxy polymers. II. Macrostructure

Abstract: A variety of measurements indicate that thermosetting epoxy polymers contain closely packed floccules and an interstitial liquid similar to the starting materials. The fioccules are thought to be of colloidal origin and appear to be ordered with respect to each other in a three-dimensional array.

Permeability separatory apparatus and processes of making and using the same

Abstract: 1,221,994. Epoxy resin compositions. DOW CHEMICAL CO. 8 Feb., 1968 [13 Feb., 1967], No. 6330/68. Heading C3B. [Also in Divisions B1-B2] Casting formulations for epoxy resins comprise (1) 14A7 parts diglycidyl ester of bisphenol, 1A1 part dimethylamino propylamine, 6A8 parts soya-1-3-propylene diamine, (2) 10 parts of diglycidyl ether of bisphenol, 2A7 parts of N-(2- phenyl - 2 - hydroxyethyl) - diethylenetriamine, 7A3 parts acetone, (3) 27A3% resorcinol diglycidyl ether, 13A7% 1,4-butanediol diglycidyl ether, 13A7% propylene glycol monoricinoleate, 5A5% chlorophenylene oxide, 37A4% maleic anhydride, 1% N-methyl morpholine, 2A5% colloidal silica. There is also reference to use of the diglycidyl ethers of dihydroxy diphenyl or hydroquinone, and to addition of amine resins as modifiers.

Particulate adhesive containing polyepoxides carboxylated butadiene-acrylonitrile copolymer and a urea derivative as a curing agent

Abstract: A CURABLE STRUCTURAL ADHESIVE IN FLOWABLE, PARTICULATE FORM COMPRISING AN EPOXY RESIN MODIFIED WITH A NITRILE RUBBER PREFERABLY CONTAINING FREE CARBOXYL GROUPS, AND AN EPOXY CURING SYSTEM WHICH PREFERABLY WILL PROVIDE A CURE AT A TEMPERATURE NOT EXCEEDING ABOUT 250*F. UPON SUBJECTION TO ABOUT 150*F., THE ADHESIVE CONVERTS TO A STATE IN WHICH IT WILL READILY ADHERE TO VARIOUS SUBSTRATES INCLUDING METALS. ALSO PROVIDED ARE A PROCESS FOR APPLYING THE ADHESIVE AS WELL AS THE SUBSTRATES CONTAINING THE ADHESIVE BOTH IN THE FUSED, NON-CURED STATE AND THE CURED STATE.

Epoxy-terminated adducts of carboxy terminated polyesters and polyepoxides

Abstract: EPOXY-TERMINATED POLYMERS COMPRISING AN ADDUCT AT AN EPOXY RESIN AND AN ACID-TERMINATED POLYMER HAVING ENTER AND AMIDE LINKAGES. THE ADDUCT INCLUDES AT LEAST TWO EPOXIDE EQUIVALENT WEIGHTS FOR EACH ACID EQUIVALENT WEIGHTS FOR EACH ACID EQUIVALENT WEIGHT OF ACID-TERMINATED POLYMER. THESE EPOXY-TERMINATED POLYMERS ARE RAPIDLY CURABLE WITH APPROPRIATE HARDENERS AND CATALYSTS AND YET FORM FLEXIBLE PRODUCTS.

Prefabricated laminated insulated wall panels

Abstract: Prefabricated insulated wall panels formed from overlying layers of heat resistant materials. The panels are capable of being assembled in abutting relation on the outer surface of a metallic enclosure. The panels have an inner fibrous insulation layer of materials such as asbestos, glass fiber, mineral wool, aluminum silicate fibers or felt secured together with inorganic binders such as bentonite, portland cement or high temperature calcium aluminate cements or an organic binder such as phenolic or latex. The insulation layer has a compressive strength sufficient to afford a suitable working surface. A heat-resistant thermosetting layer formed from an organic adhesive with a base of neoprene, rubber, silicone, or resin adhesive is applied to the insulation layer and bonds a reinforced resin laminate layer formed from polyester, phenolic, or epoxy resin, with glass fiber or fibrous asbestos. The panel joints have bonding strips of several types and configurations securing the resin laminate layer.

Pipe joint cocoon

Abstract: Upper and lower halves of cocoonlike shell of glass cloth saturated with epoxy resin surrounding the pipe joint, held in place by masking tape, ends and side seams coated with epoxy resin reinforced with crisscrossed glass tape.

Method of forming a lightweight structural assembly by joining acrylic resin balls with a polyester or epoxy resin matrix

Abstract: Method of forming a lightweight structural assembly of high structural strength comprising, in combination, a hollow member, a filler therein of hollow plastic balls and a resinous matrix therefor of a resin selected from the group consisting of epoxy and polyester resins. The method of making the assembly uses the hollow member as the mold and effects the formation and curing of the matrix resin by the exothermic reaction between the resinforming components, thereby liberating sufficient heat to cause the plastic balls to expand and subsequently upon cooling to exhibit a stressed state than increases the structural strength of the resulting assembly. The hollow member is preferably formed of a lightweight rigid material, such as aluminum, an aluminum or magnesium alloy, or a resin, and the balls are preferably formed with thin continuous spherical walls of a polymethylmethacrylate or polymethacrylate with diameters varying from one-half to 1 3/4 inches. The balls are coated with a tacky polyester or epoxy resin prior to charging the balls into the cavity to cause the balls to become attached to one another and relatively fixed in place prior to introducing the liquid resin matrix.

AC Breakdown of Epoxy Resins by Partial Discharges in Voids

Abstract: The subject of this paper is the effect of partial discharges in a void on the performance of epoxy resin insulation. Theoretical and experimental investigations are reported that seek a relationship between measurable electrical quantities and a possible breakdown of the insulation. All experiments were done under controlled conditions with samples of quartz-power filled and unfilled epoxy resin containing an artificial void of known cylindical shape and dimensions. The test specimen and the measuring circuits are described. Theoretical considerations of the equivalent circuit of the test circuit indicate that the charge fed into the specimen per pulse and the discharge power are independent of the external circuit. The electric charge and power fed into the specimen are appropriate fundamental quantities for the assessment of the pulse-type process. The theory was confirmed by measurements. It was found that the power consumed by the internal partial discharges up to a breakdown could be measured by two independent methods. Experimental results of long-time aging investigations with alternating current voltage are reported. Partial discharges in voids in epoxy resin insulation subjected to long-term voltage stressing can lead to breakdown of the insulation. The period of time of voltage application to a test specimen can be divided into two characteristic intervals, which were of different duration in the filled and unfilled resins. During the first interval, all important corona quantities (i. e., corona charge, discharge current, power and radio interference voltage) remain either constant or decrease.

Sand consolidation process

Abstract: A method is described for consolidating an unconsolidated earth formation penetrated by a well with an epoxy resin compound or mixture of epoxy compounds suitable over a wide range of temperatures. A permeability flush fluid gives an optimum combination of strength and permeabiltiy retention. The permeability flush fluid consists of a hydrocarbon oil containing a hydrocarbon oil-miscible compound. Immediately following the permeability flush fluid, a dilute solution of a curing agent is injected into the formation to harden the resin. The resin may be blended with a predominantly aromatic hydrocarbon liquid and an epoxy silane prior to injection into the formation. (6 claims)

Treatment of carbon fibres and composite materials including such fibres

Abstract: 1,180,441. Reinforced epoxy resins. NATIONAL RESEARCH DEVELOPMENT CORP. 14 Feb., 1968 [21 Feb., 1967], No. 8201/67. Heading C3B. [Also in Division C1] Epoxy resin reinforced by incorporating carbon fibres which have been surface oxidized by an oxidizing atmosphere at an elevated temperature.

Coating compositions containing a polyester composition,an epoxy resin and an aminoplast resin

Abstract: NOVEL POLYESTER COMPOSITINS RESULTING FROM THE ESTERIFICATION REACTION OF TWO OR MORE DICARBOXYLIC ACIDS OR ANHYDRIDES, A GLYCIDYL ESTER, A GLYCOL AND A POLYOL SELECTED FROM THE GROUP CONSISTING OF TRIMETHYLOL ETHANE, TRIMETHYLOL PROPANE, GLYCERINE AND PENTAERYTHRITOL ARE PROVIDED FOR USE IN FORMULATING THERMOSETTING COATING COMPOSITIONS BY BLENDING THE POLYESTER COMPOSTIONS WITH AN EPOXYHDROXY POLYETHER CONDENSATE AND AN AMINOPLAST RESIN FOR ULTIMATE USE IN COATING INDUSTRIAL APPLIANCES.

Epoxy resin coatings having improved cathodic disbonding resistance

Abstract: EPOXY RESIN POWDER COATINGS HAVING IMPROVED CATHODIC DISBONDING RESISTANCE AND WHICH CAN BE EFFICIENTLY APPLIED LY FLUIDIZED BED TECHNIQUES COMPRISE (1) A POLYEPOXIDE, (2) AN EPOXY CURING AGENT, (3) A CATALYST, AND (4) A SUITABLE BONDING ADDITIVE HEREINAFTER MORE FULLY DESCRIBED (E.G., BARIUM SULFATE, STRONTIUM CHROMATE, O-NITROPHENOL, PHOSPHORIC ACID, AND AMINOSILANES).

Reinforced polystyrene and its copolymers

Abstract: Polystyrene and copolymers thereof can be reinforced by glass fibers having a coating of silane coupling agent and a thermosetting polymer such as epoxy, phenolic, polyester, polyacrylate and melamine, to provide superior thermoplastic injection molding compositions.

Curable epoxy resin compositions containing novel disecondary diamines

Abstract: Curable epoxy resin mixtures suitable for use as casting, impregnating or laminating resins or binders, coacting or sealing compositions, characterized in that they contain I. a diepoxy compound containing two 1,2-epoxyethyl residues, II. a disecondary diamine of the formula

Bonding using epoxy resin composition and nonactivated blowing agent

Abstract: Epoxy resin composition consisting essentially of an epoxy resin component, curing agent, thermally decomposable blowing agent and optionally thermoplastic polymer, said composition, after curing, being capable of being broken up by expanding with the application of heat. It is used, for example, in joining cables by connecting core wires, slipping sleeve over portion where core wires have been connected, sealing said sleeve and sheath by said epoxy composition and thereafter curing said epoxy composition to form sealed portion, said sealed portion being capable of subsequent dismantlement.

The interpretation of electrical resistivity measurements during epoxy resin cure

Abstract: Electrical resistivity changes during the cure of epoxy resins are interpreted using a model of `hopping' conductivity. If the energy barrier against ionic movement between neighbouring hopping sites increases proportionally to the degree of cross-linking of the resin, then it is justifiable to use the rate of change of the logarithm of resistivity with time as a measure of the reaction rate. The limitations of the method are discussed in the light of the behaviour of real materials.

Mixtures of imidazole complexes and nitrogenous compound as curing agents for epoxy resins

Abstract: EPOXY RESINS ARE BLENDED WITH A CURING AGENT COMPRISING A MIXTURE OF METAL SALT COMPLEXES OF IMIDAZOLES AND NITROGENOUS COMPOUNDS SUCH AS UREA, DICYANDIAMIDE, MELAMINES AND THIOUREAS TO FORM COMPOSITIONS WHICH REMAIN IN THE UNCURED STATE FOR LONG PERIODS OF TIME AT ROOM TEMPERATURE, CURE CONVENIENTLY AT ELEVATED TEMPERATURES AND HAVE EXCELLENT SHEAR STRENGTH AND PEEL STRENGTH. THESE EPOXY RESIN COMPOSITIONS MAY BE USED AS COATINGS, ADHESIVES, POTTING COMPOUNDS, CASTINGS AND LAMINATES.

Adducts of polyepoxides and cycloaliphatic diprimary diamines and as curing agents in epoxy resin compositions

Abstract: Process for the manufacture of new adducts of polyepoxides and polyamines suitable for use as curing agents for epoxy resins characterized in that (1) a 1,2-polyepoxide compound is reacted with (2) a cycloaliphatic-aliphatic diprimary diamine in which the first primary amino group is located on an aliphatic sidechain and the second primary amino group is bonded to an endocyclic carbon atom of the cycloaliphatic ring, in a quantity ratio of 0.6 to 1.2 mols, preferably 0.7 to 1.0 mols, of the diamine (2) per 1 epoxide equivalent of the polyepoxide compound (1), with heating.