Polyimide foams provide thermal insulation and fire protection

Chemical reactions to produce polyimide foams for application as thermal insulation and fire prevention materials are discussed. Thermal and physical properties of the polyimides are described. Methods for improving basic formulations to produce desired qualitites are included

Perfluoroalkyl polytriazines containing pendent iododifluoromethyl groups

New perfluoroalkyl polytriazines containing pendent iododifluoromethyl groups are prepared by the reaction of perfluoroalkyl dinitriles with ammonia to form poly(imidoylamidines), followed by the cyclization of the imidoylamidine groups with, e.g., various mixtures of a perfluoroacyl fluoride with an omega iodoperfluoroacyl fluoride. The polytriazines obtained can be cured by heat which causes crosslinking at the iododifluoromethyl groups by elimination of iodine and formation of carbon-to-carbon bonds

Fluoroether modified epoxy composites

Addition of controlled amounts of perfluorinated alkyl ether diacyl fluoride to epoxy resin systems prior to cure results in a formulation which, exhibits improved energy absorbing properties

Process for the preparation of fluorine containing crosslinked elastomeric polytriazine and product so produced

Crosslinking elastomeric polytriazines are prepared by a 4 step procedure which consists of (1) forming a poly(imidoylamidine) by the reaction, under reflux conditions, of anhydrous ammonia with certain perfluorinated alkyl or alkylether dinitriles; (2) forming a linear polytriazine by cyclizing the imidoylamidine linkages by reaction with certain perfluorinated alkyl or alkylether acid anhydrides or halides; (3) extending the linear polytriazine chain by further refluxing in anhydrous ammonia; and (4) heating to cyclize the new imidoylamidine and thereby crosslink the polymer

Polyimide fiber-glass composite resists high temperatures

Composites synthesized from bismaleimide have superior strength and oxidation resistance at elevated temperatures when compared with similar composites prepared with epoxy or silicon polymers of similar cost. Polyimide synthesis technique and processing method yield essentially void-free fiber-glass reinforced composites

Advanced supersonic technology fuel tank sealants

Status of the fuel tank simulation and YF-12A flight tests utilizing a fluorosilicone sealant is described. New elastomer sealant development is detailed, and comparisons of high and low temperature characteristics are made to baseline fluorosilicone sealants

Preparation of crosslinked 1,2,4-oxadiazole polymer

New crosslinked 1,2,4-oxadiazole elastomers were prepared by thermally condensing a monomer having the formula H2N(HON)C-R-Q, wherein Q is a triazine ring-forming group such as nitrile or amidine or a mixture of such group with amidoxime, or a mixture of said monomer with R C(NOH)NH2 sub 2 with R in these formulas standing for a bivalent organic radical. In the monomer charge, the overall proportions of amidoxime groups to triazine ring-forming groups varies depending on the extent of crosslinking desired in the final polymer

Bifunctional monomers having terminal oxime and cyano or amidine groups

The preparation of crosslinked 1,2,4-oxadiazole elastomers is described. The technique involves thermally condensing (1) a monomer having the formula H2N(HON)C-R-Q, wherein Q is a triazine ring-forming groups such as nitrile or amidine or a mixture of such group with amidoxime, or (2) a mixture of the same monomer with R(C(NOH)NH2)2, with R in these formulas standing for a bivalent organic radical. In the monomer charge, the overall proportions of amidoxime groups to triazine ring-forming groups varies depending on the extent of crosslinking desired in the final polymer

Preparation of heterocyclic block copolymer from perfluoroalkylene oxide alpha, omega-diamidoximes

Diamidoxime monomers are intermolecularly and thermally condensed to form a heat and chemical resistant polymer containing 1,2,4-oxadiazole linkages with identical bivalent organic radicals or any combination of bivalent organic radicals selected from the group consisting of -(CX(sub 2))p-, wherein P ranges from 2 to 8 when X is fluorine and 2 to 18 when X is hydrogen, chlorine, nitro or aryl; arylene; and an oligometric or polymeric radical prepared by reacting a dicarboxylic acid halide with a fluorinated epoxide and having the formula: (CFY(OCF(sub 2)CFY)sub m)O(CX(sub 2))(sub p)O(CFYCF(sub 2)O)(sub n)CFY wherein Y is flourine or tryifluoromethyl, X is nitro, aryl, hydrogen, chlorine or fluorine, preferably the latter, p ranges from 1 to 18 and m+n ranges from 2 to 7

Application of In Situ Fiberization for fabrication of improved strain isolation pads and graphite epoxy composites

The feasibility of applying the in situ fiberization process to the fabrication of strain isolation pads (SIP) for the Space Shuttle and to the fabrication of graphite-epoxy composites was evaluated. The ISF process involves the formation of interconnected polymer fiber networks by agitation of dilute polymer solutions under controlled conditions. High temperature polymers suitable for SIP use were fiberized and a successful fiberization of polychloro trifluoroethylene, a relatively high melting polymer, was achieved. Attempts to fiberize polymers with greater thermal stability were unsuccessful, apparently due to characteristics caused by the presence of aromaticity in the backbone of such materials. Graphite-epoxy composites were fabricated by interconnecting two dimensional arrays of graphite fiber with polypropylene IS fibers with subsequent epoxy resin impregnation. Mechanical property tests were performed on laminated panels of this material to evaluate intralaminar and interlaminar shear strength, and thus fracture toughness. Test results were generally unpromising