Abstract: A proton conducting membrane includes a polyimide. The polyimide includes at least one sulfonate group and is terminated by (arylethynyl)isoindoline-1,3-dione moieties. The ethynyl unsaturation allows for the thermal or catalytic cross-linking of the membrane.

Abstract: A series of low melting and low viscosity phenylethynyl end-capped polyimides (PETIs) possessed of long term thermal and mechanical stability useful as films, melt coatings, adhesives, matrix and RTM resins and particular as coatings for optical fibers and phenylethynyl end-capped bismides blended with PETIs are disclosed. Processes for their production including: 1) modification of PETI-5 oligomer by molecular weight adjustments by blending with reactive low melting phenylethynyl end-capped imide monomers, 2) modification of the PETI-5 backbone structure with other diamine components, and 3) modification of the PETI-5 backbone with bulky fluorinated groups are also disclosed.

Abstract: A series of low melting and low viscosity phenylethynyl end-capped polyimides (PETIs) possessed of long term thermal and mechanical stability useful as films, melt coatings, adhesives, matrix and RTM resins and particular as coatings for optical fibers and phenylethynyl end-capped bismides blended with PETIs are disclosed. Processes for their production including: 1) modification of PETI-5 oligomer by molecular weight adjustments by blending with reactive low melting phenylethynyl end-capped imide monomers, 2) modification of the PETI-5 backbone structure with other diamine components, and 3) modification of the PETI-5 backbone with bulky fluorinated groups are also disclosed.

Abstract: Polyamides, polyesters, and polyamideesters are efficiently synthesized in a microwave process with precise temperature control. Compared to conventional thermal polymerizations, the microwave process takes less time and produces polymers with equivalent or superior physical properties.

Abstract: In accordance with the present invention, electropolymerization in a substantially aqueous solution is used to form thick (e.g. greater than 2 microns or 30 weight %) and thermally stable coatings of thermoplastic materials onto electrically conductive filler materials (e.g. rods, plates, fibers). In a first preferred embodiment, the thick thermoplastic matrix comprises a copolymer of 3-carboxyphenyl meleimde and styrene. In a second preferred embodiment, cyclic (and preferably aromatic) N-substituted methacrylamide monomers are electropolymerized onto electrically conductive (e.g., graphite) filler (e.g., fibers, plates, film or cloth) to form a novel polymer composite exhibiting high Tg as well as a controlled degree of cross-linking which can prevent flow at high temperature. This invention is particularly will suited for direct preparation of thermoplastic prepregs containing commercially available bundles of graphite fibers.

Abstract: In accordance with the present invention, electropolymerization in a substantially aqueous solution is used to form thick (e.g. greater than 2 microns or 30 weight %) and thermally stable coatings of thermoplastic materials onto electrically conductive filler materials (e.g. rods, plates, fibers). In a first preferred embodiment, the thick thermoplastic matrix comprises a copolymer of 3-carboxyphenyl maleimide and styrene. In a second preferred embodiment, cyclic (and preferably aromatic) N-substituted methacrylamide monomers are electropolymerized onto electrically conductive (e.g., graphite) filler (e.g., fibers, plates, film or cloth) to form a novel polymer composite exhibiting high Tg as well as a controlled degree of cross-linking which can prevent flow at high temperature. This invention is particularly well suited for direct preparation of thermoplastic prepregs containing commercially available bundles of graphite fibers.

Abstract: A pretreatment process for fabricating polyimide composites from prepreg, thereby reducing the formation of void producing or blister producing gases at elevated temperatures during a subsequent post cure cycle. The pretreatment process includes heating a prepreg to an elevated temperature and holding at said temperature for a period of time sufficient to achieve complete imidization of the prepreg but such that the material is still processable. Processes are also disclosed for the subsequent cure of the prepreg to form thermoplastic high temperature fiber reinforced composites.

Abstract: A fluorinated condensation copolyimide has repeating polymer units that include: ##STR1## in which X and Y are diamines. The copolyimide can be made by reacting a 3F-monomer and a 6F-monomer with an aromatic or aliphatic diamine. The 3F-monomer includes 4,4'-(2,2,2-trifluoro-1-phenylethylidene) diphthalic anhydride, a dialkylester of 4,4'-(2,2,2-trifluoro-1-phenylethylidene) diphthalic anhydride, 4,4'-(2,2,2-trifluoro-1-phenylethylidene) diphthalic acid, or mixtures thereof. The 6F-monomer includes 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] diphthalic anhydride, a dialkylester of 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] diphthalic anhydride, 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] diphthalic acid, or mixtures thereof.

Abstract: A high temperature fluorinated polyimide is made by forming a solution that includes a 3F-monomer and an aromatic or aliphatic diamine such that the solution has a ratio of 3F-monomer to diamine of greater than 1.05. The 3F-monomer is 4,4'-(2,2,2-trifluoro-1-phenylethylidene) diphthalic anhydride, a dialkylester of 4,4'-(2,2,2-trifluoro-1-phenylethylidene) diphthalic anhydride, 4,4'-(2,2,2-trifluoro-1-phenylethylidene) diphthalic acid, or mixtures thereof. The solution is mixed so the 3F-monomer reacts with the diamine to form a 3F-polyimide.

Abstract: Cyclic (and preferably aromatic) N-substituted methacrylamide monomers are electropolymerized onto electrically conductive (e.g., graphite) filler (e.g., fibers, plates, film or cloth) to form a novel polymer composite exhibiting high Tg as well as a controlled degree of cross-linking which can prevent flow at high temperature.

Abstract: A polyimide resin or composite may be pretreated by heating a reaction mixture that initially includes an aromatic diamine monomer, an end cap monomer, and an aromatic dianhydride monomer to a temperature between about 250.degree. C. and about 300.degree. C. for a period sufficient to completely imidize the reaction mixture to an imide resin without substantial crosslinking. A crosslinked reinforced polyimide composite article may be fabricated by heating a plurality of prepregs to a first temperature between about 250.degree. C. and about 300.degree. C. for a first period sufficient to completely imidize the prepreg without substantial crosslinking. Each prepreg has a plurality of reinforcing fibers and a reaction mixture.

Abstract: A method for making a fiber reinforced crosslinked polyimide matrix composite article that is substantially free of internal voids and surface blisters is disclosed. The method includes heating a fiber prepreg under vacuum to remove volatile impurities and volatile reaction products from the prepreg and subsequently curing the prepreg to form the article.

Abstract: Fluorinated aromatic hydrocarbons including fluorinated aromatic carboxylic acids fluorinated aromatic dianhydrides and fluorinated aromatic dialkyl esters that serve as precursor monomers for high temperature fluorinated polyimides. The fluorinated aromatic carboxylic acid monomer comprises: ##STR1## wherein X is hydrogen, carboxyl, sulfonic acid, hydroxy, alkyl, halogen or nitro and hydrates of said acids. The fluorinated aromatic dianhydride monomer comprises: ##STR2## wherein x is hydrogen, carboxyl, sulfonic acid, hydroxy, alkyl, halogen or nitro. The fluorinated aromatic dialkyl ester monomer comprises: ##STR3## wherein X is hydrogen, carboxyl, sulfonic acid, hydroxy, alkyl, halogen or nitro and Y is an alkyl group and hydrates of said esters.

Abstract: A microcrack resistant graphite fiber reinforced high temperature resin matrix composite laminate is disclosed. The laminate comprises layers having the fiber reinforcement in parallel alignment within each layer. The layers are arranged such that the fibers are oriented at 0.degree. and 90.degree. (.+-.10.degree.) in alternating layers. The specific number of plies per layer is selected so as to produce microcrack resistance. A method for making a microcrack resistant graphite fiber reinforced high temperature resin matrix composite laminate is also disclosed.

Abstract: High temperature fluorinated polyimides having repeating polymer units comprising ##STR1## wherein X is diamine. Typically, these polyimides are the copolymerization product of about 3 mole % to about 42 mole % nadic esters; about 39 mole % to about 49 mole % diamine; and about 17 mole % to about 48 mole % 4,4'9(2,2,2-trifluoro-1-phenylethylidene)-bipthalic tetra carboxylic acid dialkylester. These polimides provide the high strength properties at high temperatures yet they can be processed into solid polymers, fibers, films and composites at low temperatures and pressures.

Abstract: High temperature fluorinated polyimides having repeating polymer units of the formula ##STR1## wherein X is aromatic or aliphatic. The polyimides can be made by oxidizing 1-phenyl-1,1-bis (3,4-xylyl)-2,2,2-trifluorethane to form 4,4'(2,2,2-trifluoro-1-phenylethylidene)biphthalic tetra carboxylic acid and dehydrating that to form 4,4'(2,2,2-trifluoro-1-phenyl-ethylidene-biphthalic tetra carboxylic acid dianhydride. The dianhydride is polymerized with a diamine to form a polyamic acid which is further imidized to the polyimide. Alternatively, the dianhydride can be esterified to form a 4,4'(2,2,2-trifluoro-1-phenylethylidene)-biphthalic tetracarboxylic acid dialkylester which is then polymerized with a diamine to form a polyamic acid which can then be imidized to a polyimide.

Abstract: A low temperature processable moisture resistant polyimide and fiber reinforced composite of such a polymer and methods for making the same. The polyimide resin has repeating polymer units of the formula ##STR1## wherein n is 2 to about 20 and the molecular weight of the polymer chain is such that the polymer absorbs below about 0.2% by weight moisture at room temperature. The polyimide is made by reacting 4,4'(hexafluoroisopropylidene)bis(o-phthalic anhydride) with a diamine having the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2 wherein n is 2 to about 20 to form a polyamic acid. The polyamic acid is imidized to form the polyimide prepolymer and then further polymerized by exposing the polyimide prepolymer to heat to form the polymer described above. The composite can be made using the above process by coating fibers with the polyimide prepolymer, stacking layers of the coated fibers in a mold, and hot pressing the stacked impregnated fibers.

Abstract: A low temperature processable, thermoplastic polyimide and methods for making and using the same. The polyimide has repeating polymer units of the formula ##STR1## wherein n is 2 to about 20 and the molecular weight of the polymer chain is about 5,000 to about 50,000. The polymer is made by reacting 4,4'-(hexafluoroisopropylidene)bis(o-phthalic anhydride) with a diamine having the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2 wherein n is 2 to about 20 to form a polyamic acid. The polyamic acid is imidized to form the polyimide described above. The polyimide is particularly adapted to use as a hot melt adhesive by placing it between two articles and applying heat and pressure.

Abstract: A low temperature processable, thermoplastic polyimide and methods for making and using the same. The polyimide has repeating polymer units of the formula ##STR1## wherein n is 2 to about 20 and the molecular weight of the polymer chain is about 5,000 to about 50,000. The polymer is made by reacting 4,4'-(hexafluoroisopropylidene)bis(o-phthalic anhydride) with a diamine having the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2 wherein n is 2 to about 20 to form a polyamic acid. The polyamic acid is imidized to form the polyimide described above. The polyimide is particularly adapted to use as a hot melt adhesive by placing it between two articles and applying heat and pressure.

Abstract: A moisture resistant polyimide adhesive is disclosed comprising a polymer having repeating units of the formula: ##STR1## where n is equal to about 8 to about 20. The improved moisture resistance of the polymers according to the present invention is indicated by a moisture pick-up of less than about 0.6% by weight after 24 hour immersion in room temperature water. The polymer also exhibits a tensile strength greater than about 1800 psi (1.24.times.10.sup.7 NT/M.sup.2). In addition to their improved adhesive and moisture resistant properties, the polymers according to the present invention exhibited such properties with cure times of less than about one hour at temperatures up to about 320.degree. C.