Abstract: The properties of a thermosetting furan based polymer are improved by incorporating therein at least one metal selected from the group consisting of niobium and/or tantalum.

Abstract: There are disclosed polymers containing tungsten chemically bonded in the polymer chain. The polymers are obtained by reacting 2-furanacrylic acid or 2-furoic acid with the reaction product of tungsten carbonyl with pyrrolidine. These polymers are useful as multi-cycle reimpregnation resins.

Abstract: A method is provided for splicing carbonized PAN tows in which the tows to be spliced are cut square and coated at the ends thereof with a resin solution, following which the coated ends are joined together, heated so as to cure the resin solution and then pinched to compact the resulting splice. The resin solution is comprised of a mixture of a solid acrylic polymer, a liquid acrylic polymer, a solid epoxy resin and a solvent.

Abstract: Metal complexes are obtained by reacting furfurylamine with a metal carbonyl selected from the group consisting of tungsten carbonyl, molybdenum carbonyl and chromium carbonyl. Multi-cycle reimpregnation resins are obtained by reacting one of these metal complexes with furfuryl alcohol.

Abstract: There are disclosed thermosetting resoles containing chemically bonded boron, tungsten and/or zirconium atoms. The metal containing resoles of this invention are useful, for example, as reimpregnation resins.

Abstract: There are disclosed polymers containing tungsten chemically bonded in the polymer chain. The polymers are obtained by reacting 2-furanacrylic acid or 2-furoic acid with the reaction product of tungsten carbonyl with pyrrolidine. These polymers are useful as multi-cycle reimpregnation resins.

Abstract: A composition is disclosed for treating carbon fibers to provide an epoxy finish thereon, comprising an epoxy resin and an effective amount of a non-ionic emulsifier in the form of a block polymer consisting of a poly(oxypropylene) chain having poly(oxyethylene) groups at both ends of said chain, said polymer terminating in a primary hydroxyl group, said polymer having a molecular weight ranging from about 1100 to about 14,000. The process for treating the carbon fibers comprises applying the aqueous resin emulsion to the fibers and thereafter drying the fibers.

Abstract: In a method of producing purified carbonized material from polyacrylonitrile precursor material, the precursor material is initially oxidized and partially carbonized prior to purification treatment to remove alkali and alkaline earth metal impurities. Following purification, the material is substantially completely carbonized. Purification is accomplished by weaving oxidized and partially carbonized tows of the polyacrylonitrile precursor material into a fabric and thereafter contacting the fabric with an aqueous acid solution at an elevated temperature followed by rinsing with a solvent which is substantially free of alkali and alkaline earth metal ions and which is at an elevated temperature. Purification of the tows after partial carbonization thereof limits the amount of tow weight loss and shrinkage occurring after the fabric is formed.

Abstract: Three-dimensional thick fabrics are made from a laminate of fabric plies by first inserting pointed rods through the laminate to form rows of holes after which needles are reciprocated through the different holes to pull loops of various yarns through the holes. The loops of yarns in adjacent holes are interlocked to hold the plies together. A guide releasably clamped to each yarn controls tension in the yarn while a doffing point is employed to insure that the needle passes through a loop just formed when penetrating the next hole to insure interlock of the loops. Hollow circular objects are formed by winding a length of fabric a selected number of times around a form, following which the pointed rods are used to form holes in the resulting laminate with the needles and yarns being used to form the interlocking loops through the thickness of the laminate.

Abstract: In a process for continuously pulling a web of tows of carbonizable material under tension through an oxidizing oven, the web is introduced into the oxidizing oven by initially feeding a leader in the form of a web of heat-resistant cloth through the oven and then heating the oven if the oven is not already hot. The trailing edge of the leader which remains outside of the oven is then spliced to the leading edge of the web of carbonizable tows, and the leader is used to pull the web of carbonizable tows into and through the hot oven. Use of the heat-resistant leader greatly minimizes wastage within the web of carbonizable tows. Splicing of the trailing edge of the lead to the leading edge of the web of carbonizable tows is accomplished by taping, stitching and folding the two edges to form loops therein into which elongated rods are inserted. The two edges are then secured within a splice bar, the opposite halves of which define slots for receiving the two edges and the included rods.

Abstract: A method is provided for splicing carbonized PAN tows in which the tows to be spliced are cut square and coated at the ends thereof with a resin solution, following which the coated ends are joined together, heated so as to cure the resin solution and then pinched to compact the resulting splice. The resin solution is comprised of a mixture of a solid acrylic polymer, a liquid acrylic polymer, a solid epoxy resin and a solvent.

Abstract: Apparatus for removing a fill yarn from a web of warp tows advances the web lengthwise across a tabletop having opposite pairs of bars at the leading edge thereof for separating the outermost tow at each of the opposite edges of the web from the remaining tows within the web. Rotatable cutting wheels which are resiliently urged against the top of a rotating shaft at the underside of the web sever the fill yarn between the outermost tows and the remaining tows of the web to form separate fill yarn lengths extending across the width of the web. As the advancing web is then divided along a central portion thereof, the separate lengths of fill yarn are removed by a hook mounted within a central portion of the tabletop and reciprocating between positions above and below the tabletop so as to hook each separate length of fill yarn and begin pulling it down through the tabletop.

Abstract: It is disclosed that the properties of epoxy resins may be improved by incorporating therein at least one metal selected from the group consisting of boron, molybdenum, rhenium, tungsten and zirconium. The selection of a particular metal atom for incorporation into the epoxy resin or a combination of these metals will depend on the specific resin properties desired.

Abstract: A novel bis-imide matrix resin system especially useful for high temperature, high performance, graphite fiber composites is disclosed. Microcracking of composites is reduced and transverse strength is increased by the addition to the resin system of 1 to 15 percent of compatible elastomers, such as polyether sulfones, bis-phenol linear homopolymeric epoxies or polyacrylic esters. The resin system comprises 50 to 95 percent by weight of ethylenically unsaturated bis-imides, preferably a low melting mixture of a major portion of maleimides of aromatic amines with a minor portion of maleimides of an aliphatic amine and 5 percent to 35 percent by weight of a diunsaturated low-temperature cross-linking agent such as divinyl benzene which gels the bis-imide at low temperatures. Room temperature tackiness, heat resistance and cross-link density are improved by the presence of 1 to 10 percent of a trifunctional curing agent.

Abstract: A novel bis-imide matrix resin system comprising 50 to 95 percent by weight of ethylenically unsaturated bis-imides, preferably a low melting mixture of a major portion of maleimides of aromatic amines such as toluene diamine and methylene dianiline with a minor portion of maleimide of an aliphatic amine such as trimethyl hexamethylene diamine and 5 percent to 35 percent by weight of a diunsaturated low-temperature cross-linking agent such as divinyl benzene which gels the bis-imide at low temperatures. This reduces stress between the matrix resin and the surface of the reinforcing fiber, thus reducing the tendency to form microcracks. Room temperature stability is improved by the presence of 0.5 to 5 percent of an oxidation inhibitor such as hydroquinone. The resin is useful as a matrix resin for high performance, graphite fiber reinforced composites.CROSS REFERENCE TO RELATED APPLICATIONThis application is a continuation of Ser. No. 248,978, filed Mar. 30, 1981, now U.S. Pat. No.

Abstract: Reinforcement fiber for fiber-reinforced resin composites such as graphite tows are spliced by applying a solution of a linear, soluble, high glass transition temperature polyimide having good thermal-oxidative stability to the broken ends of a fiber, placing the ends in contact and removing solvent. The preferred polyimide is an aromatic-cycloaliphatic diamine such as 5,(6)-amino-1-(4' amino phenyl)-1,3-trimethylindane (DAPI) imidized with a dianhydride such as PMDA or BTDA. The soluble polyimide can be preapplied to the fiber as a sizing. The splices are not apparent by visual inspection nor by instrumental scanning of cured composites indicating there is no blistering nor loss of strength.

Abstract: There is disclosed a method of treating carbon fibers to provide an epoxy resin finish thereon. An aqueous emulsion of an epoxy resin is applied to the fibers and the fibers are thereafter dried. An effective amount of two different emulsifying components are used in the epoxy resin emulsion. One of the emulsifying components is a long chain aliphatic alcohol containing from eight to 18 carbon atoms. The other emulsifying component is a quaternary ammonium salt having the formula: ##STR1## wherein R is an aliphatic radical containing from 12 to 18 carbon atoms, or a mixture of such radicals, each R' may be the same or different radicals selected from methyl and ethyl, and x is bromine or chlorine.

Abstract: A carbon-organic resin composite which has been initially shaped as by molding and in which the resin binder has been at least partially precured is transformed into an all-carbon composite and substantially densified by a continuous process in which the composite is continuously heated at different temperatures and subjected to increased pressure. Initially, the composite is heated at a first rate to a temperature on the order of 1000.degree. F., the first rate and the increased pressure applied to the composite being selected to substantially decompose the resin rapidly but without delamination or other damage to the composite. Heating is then continued at a second rate until the composite undergoes substantial softening and becomes plastic, typically at a temperature in excess of 3500.degree. F. Thereafter the composite is maintained at a high temperature, typically in excess of 5000.degree. F.

Abstract: Fibrous PAN material in raw or oxidized form is purified of alkali metals, particularly sodium, and alkaline earth metals by treating with an aqueous acid solution such as hydrochloric acid having a concentration of at least 0.5% by weight and preferably at least 3% and a temperature greater than 100.degree. F. and preferably at least 125.degree. F. but not greater than the temperature at which the aqueous acid solution boils, for 5-120 minutes and preferably at least about 15 minutes. An ion exchange occurs between the acid and the PAN material, and alkali and alkaline earth metal salts are formed. The PAN material is then rinsed in solvent such as deionized water which is substantially free of metallic ions at a temperature which is preferably at least about 150.degree. F.

Abstract: A novel bis-imide matrix resin system comprising 50 to 95 percent by weight of ethylenically unsaturated bis-imides, preferably a low melting mixture of a major portion of maleimides of aromatic amines with a minor portion of maleimide of an aliphatic amine and 5 percent to 35 percent by weight of a diunsaturated low-temperature cross-linking agent such as divinyl benzene which gels the bis-imide at low temperatures. This reduces stress between the matrix resin and the surface of the reinforcing fiber, thus reducing the tendency to form microcracks. Microcracking is further reduced and transverse strength is increased by the addition of 0 to 15% of compatible elastomers to the resin and cross-linking agent. Room temperature tackiness, heat resistance and cross-link density are improved by the presence of 0 to 10% of a trifunctional curing agent.