Abstract: Described are flexible polyimide foams having enhanced compression characteristics and softness for use in the manufacture of seat cushions and methods for the production of such foams and precursors therefor. These foams are produced from novel polyimides prepared by reaction of at least one aromatic or heterocyclic primary diamine with a mixture of at least two organic tetracarboxylic acids or derivatives thereof, at least one of which is from 1 to 40 mol percent of a 2-(vicinal-dicarboxycyclohexenyl)succinic acid or derivative thereof and a second of which is an aromatic tetracarboxylic acid or derivative thereof.

Abstract: Described are ways of improving the yields of specification grade polyimide on a consistent basis from one run to the next, by use of improved microwave-based foaming processes. In one such process, during the application of the microwave radiation, the body of polyimide precursor and of the foam structure as it is developing therefrom are maintained under a substantially vapor-impermeable microwave-compatible shroud that does not substantially restrict or impede development of the foam structure; and the microwave radiation is directed upon the top, sides and ends of the body of polyimide precursor and of the foam structure as it is developing, but the extent to which such radiation impinges upwardly into the bottom of said body and said foam structure is curtailed, preferably by means of a metallic shield located below the precursor and developing foam structure.

Abstract: Described are flexible polyimide foams having enhanced compression fatigue life and softness for use in the manufacture of seat cushions and methods for the production of such foams and precursors therefor. These foams are produced from novel polyimides prepared by reaction of an organic tetracarboxylic acid or derivative thereof, preferably an ester with (a) about 1 to about 50 mol percent of a diester of (i) a primary amino-substituted aromatic carboxylic acid, and (ii) a polymethylene glycol, and (b) at least one aromatic or heterocyclic primary diamine. Foams can be produced having (a) a fatigue life as determined by ASTM test procedure D 3574-81 using foam specimens from three to five inches in thickness of at least 15,000 cycles, or (b) an indentation force deflection as determined by ASTM test procedure D3574-81 on foam specimens of one-inch thickness of less than 40 pounds of force at 25% deflection and less than 180 pounds of force at 65% deflection, or both of (a) and (b).

Abstract: The invention relates to polyamide pellets for use in the production of high molecular weight polytetramethyleneadipamide articles. The polyamide pellets have sizes of between 1 mm and 20 mm and porosity of between 0.1 and 20 vol %. Prepolymer polyamide pellets have a crushing strength of at least 0.5, and after-condensed pellets have crushing strength of at least 15 kg.

Abstract: Described are flexible polyimide foams having enhanced compression fatique life and softness for use in the manufacture of seat cushions and methods for the production of such foams and precursors therefor. These foams are produced from novel polyimides prepared by reaction of an organic tetracarboxylic acid or derivative thereof, preferably an ester with (a) about 1 to about 50 mol percent of a diester of (i) a primary amino-substituted aromatic carboxylic acid, and (ii) a polymethylene glycol, and (b) at least one aromatic or heterocyclic primary diamine. Foams can be produced having (a) a fatigue life as determined by ASTM test procedure D3574-81 using foam specimens from three to five inches in thickness of at least 15,000 cycles, or (b) an indentation force deflection as determined by ASTM test procedure D3574-81 on foam specimens of one-inch thickness of less than 40 pounds of force at 25% deflection and less than 180 pounds of force at 65% deflection, or both of (a) and (b).

Abstract: This invention relates to a process for the production of high strength polybenzimidazole filaments and molded products made from such filaments. The filaments produced by this process contain from about 10 to about 50 percent by weight residual solvent and can be heated at a temperature of about 350.degree. C. to about 600.degree. C. to produce three-dimensional foamed articles.

Abstract: Described are ways of improving the yields of specification grade polyimide foam on a consistent basis from one run to the next by use of improvements in microwave-based foaming processes. While a body of polyimide precursor is exposed to microwave radiation, the body of polyimide precursor and of the foam structure as it is developing therefrom are kept under a substantially vapor-impermeable microwave-compatible shroud that does not substantially restrict or impede development of the foam structure. For this purpose use may be made of a shroud composed of a polymer film. Mechanisms by which the shroud produces the improved results are discussed, and methods based thereon are set forth.

Abstract: A dye-containing porous plastic element, comprising a plastic body having interconnected capillary passageways, and a dry, water-soluble dye located within the passageways. The passageways extend to at least one surface of the body, and the size of the passageways are such that the body, when contacted with water, can absorb the water to wet the dye and make it soluble. The plastic body comprises fused granules of plastic interspersed with dry granules of dye. The plastic granules may have a diameter, prior to fushion, of between about 50 and 800 microns, preferably between about 100 and 300 microns. The dry dye comprises between about 5 percent and 35 percent of the element, by weight, and preferably between about 10 per cent and 20 percent .

Abstract: Rigid flame resistant polyurethane foams are made by reacting an aromatic polyisocyanate with a mixture of 25-75% oligoester and another isocyanate-reactive material in the presence of a blowing agent at an NCO index of less than 300. These foams which have an ASTM E-84 Class 1 rating are particularly useful in construction applications.

Abstract: A microporous membrane suitable for use in microfiltration. The membrane is a hydrophilic skinless sheet, formed of polytetramethylene adipamide, either alone, or in admixture with at least one other polyamide.

Abstract: A method of making structural panels having a controlled density polyimide core, generally with at least one face sheet. An open cell polyimide foam panel is impregnated with a liquid polyimide precursor, compressed to squeeze out all but a desired quantity of the polyimide precursor and dried. One or two face sheets are impregnated with the same liquid polyimide precursor and placed on one or both faces of the foam panel, with pre-drying of the face sheet if desired. This assembly is placed in a mold and subjected to slight compression. The assembly is heated to a moderate temperature for a suitable time to take on the mold configuration. Then the assembly is heated to the curing temperature of the polyimide precursor for a period sufficient to cause curing. The resulting structural panel has a selected density, which determines strength and rigidity, weight and other physical characteristics, controlled by the amount of precursor allowed to remain after the impregnation foam compression step.

Abstract: A process for the production of cellular products which comprises incorporating a blowing agent into rubber or a thermoplastic material uses as the blowing agent a tetrazole compound represented by the formula: ##STR1## in which R represents an alkyl, cycloalkyl, hydroxyalkyl, polyhydroxyalkyl, aryl, alkylaryl, aralkylene, alkenyl, alkenylaryl or alkenylaralkylene group.The novel blowing agents of the present invention include compounds which are liquids which may be directly incorporated into the molten rubber or thermoplastic material. The blowing agents of this invention are especially useful, as indicated, with polymers and copolymers that have high processing temperatures as they minimize polymer degradation and provide products with increased impact strengths.

Abstract: A method for forming a molded thermoplastic foam structure comprising partially filling a mold with solvent imbibed particles of a thermoplastic resin, pressurizing said mold under conditions such as to prevent vaporization of said blowing agent during subsequent polymer melting, heating said polymer to a flowable state, releasing the mold pressure to permit foaming of the melt and expansion of the foamed polymer within the mold.

Abstract: Disclosed is a process for the preparation of a polyamideimide semi-flexible foam wherein a foam precursor is first prepared by heating together a mixture of an organic polyisocyanate, an aromatic polycarboxylic compound and a catalyst comprising a cyclic phosphorus compound, optionally in the presence of a surfactant until at least about 45 percent of the theoretical carbon dioxide has been evolved. The solidified precursor is comminuted and then heated to complete the reaction producing polyamideimide foam.

Abstract: A composition and a process for the preparation of modified polyimide foams possessing outstanding resistance to high humidity environments which comprises the step of preparing a foamable composition by mixing a solution of an ester of benzophenonetetracarboxylic acid dianhydride and caprolactam with a polyamine to form a resin precursor which when heated foams contemporaneously with the polymerization of the reactants. Two solvents with different boiling points are used to produce a two phase system which yields spray dried powders completely free of the lower boiling point solvent.

Abstract: Microporous polymeric films having good water vapor transmission rates and hydrostatic resistance to the penetration of liquid water are obtained by stretching a composition consisting of a matrix of a thermoplastic orientable polymer having a hydrophobic surface, a glass transition temperature of less than 25.degree. C., a Vicat softening point of more than about 25.degree. C., an ultimate elongation between those two temperatures of at least 100%, and a flexural modulus of less than 200 MPa and a particulate filler having an aspect ratio of less than 3, an average diameter of 0.05-50 m, a negligible attraction to the matrix polymer, and a surface tension no higher than that of the matrix polymer at the latter's melting temperature.Such films are useful in applications involving separation of liquids and vapors, e.g., in making "breathing" waterproof garments or linings.

Abstract: A permselective membrance suitable for obtaining fresh water by the desalination of sea water and salt water is provided herein, said permselective membrane being prepared by the reaction of an aromatic polycarboxylic acid component with a mixed diamine component comprising a diaminodiphenylsulfone compound of the formula (I), ##STR1## wherein R.sup.1 is hydrogen atom or a C.sub.1 -C.sub.12 hydrocarbon group, R.sup.2 s may be same or different, each representing a monovalent organic group, and n is an integer of 0 or 1 to 3, and an alicyclic diamine compound containing two secondary amino groups in the same or different ring(s).

Abstract: The present invention is a process for the preparation of polybenzimidazole foams. Polybenzimidazoles containing 10 to 30 percent by weight residual solvent can be heated at a temperature of about 350.degree. C. to about 600.degree. C. to produce three dimensional foamed articles.

Abstract: A high temperature, flame resistant polyimide foam material and methods of making open and closed cell, rigid and flexible foams from common precursors. An aromatic tetracarboxylic dianhydride is reacted with an amino and an alcohol or mixtue of alcohols to produce an N-substituted imido acid ester. The product is then reacted with an aromatic diamine. The resulting liquid is dried, ground to a course powder, and classified into sizes from 0.25 mm to 2 mm by sieving. The powder is suitable for foaming without further modification, by expansion at 100 to 3000 in a closed mold to form a well consolidated, uniform, mostly closed cell product. When expanded unrestrictedly, open cell flexible or rigid consolidated foams are produced, depending on choice of alcohol(s). The foams have excellent resistance to heat and flame, and bond well to glass prepreg to form rigid structures.

Abstract: Aliphatic thermoplastic polyamide porous membranes are reacted with an acid halide of basicity above one to provide acid radicals within the membrane. The acid halide may be derived from an aromatic carboxylic acid or an aromatic derivative of a chlorosilane. The substituted aliphatic polyamide porous membrane lend themselves to the preparation of chemical derivatives of the membrane which are not readily available by aqueous synthesis and to increased density of derivatives which otherwise may be prepared by water.

Abstract: A high temperature, flame resistant polyimide foam material and methods of making open and closed cell, rigid and flexible foams from common precursors. An aromatic tetracarboxylic dianhydride is reacted with an amino acid and an alcohol or mixture of alcohols to produce an N-substituted imido acid ester. The product is then reacted with an aromatic diamine. The resulting liquid is dried, ground to a course powder, ad classified into sizes from 0.25 mm to 2 mm by sieving. The powder is suitable for foaming without further modificaiton, by exapansion at 100 to 3000 in a closed mold to form a well consolidated, uniform, mostly closed cell product. When expanded unrestrictedly, open cell flexible or rigid consolidated foams are produced, depending on choice of alcohol(s). The foams have excellent resistance to heat and flame, and bond well to glass prepreg to form rigid structures.

Abstract: A high temperature, flame resistant polyimide foam material and methods of making open and closed cell, rigid and flexible foams from common precursors. An aromatic tetracarboxylic dianhydride is reacted with an amino acid and an alcohol or mixture of alcohols to produce an N-substituted imido acid ester. The product is then reacted with an aromatic diamine. The resulting liquid is dried, ground to a course powder, and classified into sizes from 0.25 mm to 2 mm by sieving. The powder is suitable for foaming without further modification, by expansion at 100 to 3000 in a closed mold to form a well consolidated, uniform, mostly closed cell product. When expanded unrestrictedly, open cell flexible or rigid consolidated foams are produced, depending on choice of alcohol(s).

Abstract: This invention concerns a process for producing a molded thermoplastic resin by interposing during molding a thermoplastic resin different from the thermoplastic resin to be molded as a skin layer between the die surface and the thermoplastic resin to be molded. A lubricant is provided to lubricate the interface between the die surface and the skin layer. After molding, the skin layer with lubricant is removed.

Abstract: An expandable polyetherimide composition comprising (A) polyetherimide and (B) a blowing agent containing in the said agent at least 10% by weight of a volatile organic foaming component having a solubility parameter [.delta..sub.c ] satisfying the following equation.delta..sub.p -1.14.ltoreq..delta..sub.c .ltoreq..delta..sub.p +1.14,wherein .delta..sub.p is the solubility parameter of the polyetherimide, a dielectric constant of not less than 15, and a boiling point at normal pressure of not higher than 80.degree. C.; and a foam material obtained therefrom.

Abstract: Methods of making low density modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxime. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder. A suitable hydrated compound which is stable up to at least about 100.degree. C. is mixed with the powder. A foam is then produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. The addition of the hydrated compound is found to result in an exceptionally low density foam.

Abstract: Aliphatic thermoplastic polyamide porous membranes are reacted with an acid halide of basicity above one to provide acid radicals within the membrane. The acid halide may be derived from an aromatic carboxylic acid or an aromatic derivative of a chlorosilane. The substituted aliphatic polyamide porous membrane lend themselves to the preparation of chemical derivatives of the membrane which are not readily available by aqueous synthesis and to increased density of derivatives which otherwise may be prepared in water.

Abstract: Methods of foaming and fully curing polyimide resins entirely by the application of microwave energy. Foamable polyimide resins may be prepared by esterifying a suitable dianhydride, reacting the product with a suitable diamine, drying the resulting product and heating to spontaneously form a foam. In the past, such materials could be foamed but could not be satisfactorily cured to a resilient foam entirely by microwave energy. Post-foaming direct application of thermal energy was required to produce a satisfactory foam. We have found that adding a suitable oxoimine, such as caprolactam, to the reaction mixture results in a foam material which is fully and completely cured entirely by the application of microwave energy, considerably simplifying the process and reducing costs.

Abstract: The present invention is a process for the preparation of novel polybenzimidazole foams. The foams exhibit a closed cellular structure and are prepared by forming a polybenzimidazole solution, adding sulfuric acid to the polybenzimidazole solution, removing the solvent, and heat treating the polybenzimidazole at a temperature of about 350.degree. to 600.degree. C.

Abstract: A process for the production of 2-aryl-4-acyl-1.3.4-oxdiazolones-(5), in which an aromatic carboxylic acid hydrazide is reacted at a pH value of from 1.8 to 3.0 with phosgene in a mixture consisting of water and acetone at a temperature of from 0.degree. C. to 50.degree. C., subsequently the pH is increased to from 9.5 to 11.0, then about 100 mol % of a carboxylic acid chloride or about 50 mol % of a dicarboxylic acid chloride (based on mols of carboxylic acid hydrazide) is added and optionally from 10.sup.-4 to 1.0 mol % (based on mols of carboxylic acid hydrazide) of a tertiary amine or phosphine is added as a catalyst and the reaction is completed at a temperature from 0.degree. C. to 50.degree. C.

Abstract: Poly(p-phenyleneterephthalamide) fibers having a very high tensile strength is described. The fibers consist essentially of poly(p-phenyleneterephthalamide) having an inherent viscosity of at least 5 dl/g as determined at 25.degree. C. in sulfuric acid having a concentration of 98 wt. % at a polymer concentration of 0.5 g/dl. The fibers are composed of single filaments of 0.5 to 3 denier, wherein the single filament tensile strength is at least 35 g/denier. The macrovoid number, hereinbefore defined, of the fibers is not more than 10 per 100 mm. The asymmetry, hereinbefore defined, of the fibers is not more than 0.2.

Abstract: Methods of making modified polyimide compositions and the resulting compositions. A polyimide forming material is prepared by treating an aromatic dianhydride with an esterifying solvent, then adding a suitable diamine. In order to obtain a foam which is non-friable and resistant to repeated compressive forces, the selected diamine must contain an aliphatic moiety in the chain. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient, flexible non-friable foam.

Abstract: Pneumatic cellular aromatic polyamide articles characterized by(a) being articles prepared substantially from aromatic polyamide.(b) said articles having numerous bubbles at the void ratio in the range of 10 to 95%,(c) said bubbles being substantially enclosed in said articles, and(d) said articles having an average thickness in the range of 0.2 to 10 mm on the cross section made by cutting them at right angles to the longest axis.The present invention provides also a process for the preparation thereof. According to the present invention, there are suitably provided pneumatic cellular aromatic polyamide article having a high strength and a wide range of void ratio, comparatively heavy thickness, excellent heat resistance and thermal insulation.

Abstract: Methods of making modified polyimide compositions and the resulting compositions. A polyimide forming material is prepared by treating an aromatic dianhydride with an esterifying solvent, then adding a suitable diamine. In order to obtain a foam which is non-friable and resistant to repeated compressive forces, the selected diamine must contain an aliphatic moiety in the chain. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient, flexible non-friable foam.

Abstract: A polyimide and a process for its preparation wherein the polyimide is prepared from reaction of an organic tetracarboxylic acid or derivative thereof with a mixture of an aromatic diamine and an amine-terminated fluoroether. The polyimides of the invention are particularly useful in the preparation of flexible foams.

Abstract: A spherical porous polyimide powder which is thermally infusible and is insoluble in an organic solvent, comprising spherical porous particles of a weight average particle diameter of 1 to 20 .mu.m comprising an aromatic polyimide having an inherent viscosity measured in sulfuric acid at a concentration of 0.5 g/dl at temperature of 30.+-.0.01.degree. C. of 0.1 to 2.0, wherein a packed bulk density is 100 to 600 g/l and a specific surface area measured by a nitrogen absorption method is 1 m.sup.2 /g or more.

Abstract: Methods of making low density modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxime. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder. A suitable hydrated compound which is stable up to at least about 100.degree. C. is mixed with the powder. A foam is then produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. The addition of the hydrated compound is found to result in an exceptionally low density foam.

Abstract: The present invention is directed to derivatives of azoles, their preparation and their use as chemical blowing agents for thermoplastic molding compositions. The agents of the invention are characterized in their improved compatibility with the resin wherein they are incorporated.

Abstract: Methods of making low density modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxime. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder. A suitable hydrated compound which is stable up to at least about 100.degree. C. is mixed with the powder. A foam is then produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. The addition of the hydrated compound is found to result in an exceptionally low density foam.

Abstract: Pneumatic cellular aromatic polyamide articles characterized by(a) being articles prepared substantially from aromatic polyamide.(b) said articles having numerous bubbles at the void ratio in the range of 10 to 95%,(c) said bubbles being substantially enclosed in said articles, and(d) said articles having an average thickness in the range of 0.2 to 10 mm on the cross section made by cutting them at right angles to the longest axis.The present invention provides also a process for the preparation thereof. According to the present invention, there are suitably provided pneumatic cellular aromatic polyamide articles having a high strength and a wide range of void ratio, comparatively heavy thickness, excellent heat resistance and thermal insulation.

Abstract: Method and apparatus for the production of porous tubing. One extrudes a homogeneous mixture of at least two components, one component a meltable polymer and the other component a liquid inert in relation to the polymer, both components forming a binary system which in liquid aggregate state displays a range of complete miscibility and a range with a miscibility gap, at a temperature above the separation temperature, substantially vertically upwardly using a circular slot nozzle and blowing of gas or dosing-in of liquid into the interior of the nozzle, into a bath, which displays a temperature below the separation temperature, allows the tubing to solidify, and extracts or lixiviates the tubing. Preferred embodiments include the use of water at a temperature from 15.degree. to 90.degree. C.

Abstract: Methods of making modified polyimide/polyimide-amide foams having selected compressive resistance and density characteristics and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxoimine. Within the mole ratio range of oxoimine to dianhydride of about 0.5:1 to about 0.05:1 the compressive resistance of the final foam can be selected in accordance with the intended end use of the foam. Density and compressive resistance varies inversely with the oxoimine quantity in the ratio, being greatest with the 0.5:1 ratio and lowest with the 0.05:1 ratio. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder or film. A foam is produced by heating the mateial to reaction temperature for a period sufficient to produce a stable foam.

Abstract: A high temperature and flame resistant closed cell polyimide foam material and methods of making the foam. An aromatic tetracarboxylic acid dianhydride is reacted with an oxomine to produce an N-substituted imide, which is then esterified with a suitable alcohol. The resulting liquid is dried and the dry residue is reduced to a uniform powder having particles with diameters generally in the 0.5 to 10 mm. range. The powder is preferably further dried, either before or after final size reduction, in a moderate vacuum at moderate temperature to remove any excess residual alcohol. The powder spontaneously expands to form a closed cell foam when heated to a temperature in the range of about 90.degree. to 150.degree. C. for a suitable period. When the powder is expanded in a closed mold, a well consolidated, uniform, closed cell foam product results. When expanded in an unrestricted manner, closed cell "macroballoons" having average diameters between about 0.4 to 15 mm. result.

Abstract: A high temperature and flame resistant closed cell polyimide foam material and methods of making the foam. An aromatic tetracarboxylic acid dianhydride is reacted with an oxomine to produce an N-substituted imide, which is then esterfied with a suitable alcohol. The resulting liquid is dried and the dry residue is reduced to a uniform powder having particles with diameters generally in the 0.5 to 10 mm. range. The powder is preferably further dried, either before or after final size reduction, in a moderate vacuum at moderate temperature to remove any excess residual alcohol. The powder spontaneously expands to form a closed cell foam when heated to a temperature in the range of about 90.degree. to 150.degree. C. for a suitable period. When the powder is expanded in a closed mold, a well consolidated, uniform, closed cell foam product results. When expanded in an unrestricted manner, closed cell "macroballoons" having average diameters between about 0.4 and 15 mm. result.

Abstract: This invention relates to polyaminoester thermosetting resins prepared by reacting polyalkylene maleate oligomers with polyfunctional amines via a Michael type addition reaction. The reaction is preferably conducted by a RIM process. Alpha, beta ethylenically unsaturated monomers, which are slow to react with amines, may be added to the reaction to copolymerize with the maleate functionality in a post cure step. The polyaminoester thermosetting resins are useful as plastics, coatings, resin modifiers, and elastomers.

Abstract: A thermosettable polyaminoester composition useful as a plastic, coating, resin modifier, and elastomer is provided. The thermosettable polyaminoester is formed by reacting one or more acrylic or methacrylic terminated polyalkylene maleate or fumarate oligomers with one or more polyamines and optionally with one or more alpha, beta-ethylenically unsaturated monomers. The composition is especially useful in the RIM process.

Abstract: Methods of making modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxoimine. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having varying physical properties.

Abstract: Copolyimide foams derived from a diester of 3,3',4,4'-benzophenonetetracarboxylic acid, an aromatic diamine, and a heterocyclic diamine. A molar concentration of the heterocyclic diamine approaching but not exceeding 0.42 is employed. This results in a flexible foam with a homogeneous cellular structure and a reduced compression set loss.

Abstract: Methods of making modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxoimine. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having varying physical properties.

Abstract: Methods of making modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxoimine. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having varying physical properties.

Abstract: Methods of making modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxoimine. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder or film. A foam is produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. Depending upon heating conditions, a polyimide, polyimide-amide or mixture thereof may be produced, resulting in foams having varying physical properties.