Abstract: By compressing and heat curing a non-resilient, non-flexible recurable material formed by subjecting cured polyimide foam to the action of pressurized steam, a wide variety of useful articles may be produced. These include tough, flame-resistant plastic films, sheets, panels, boards, and shapes in general; composites (both reinforced and unreinforced); and laminates and other articles in which separate shapes or parts are bonded together by a new type of tough, flame-resistant adhesive. Additionally, heretofore worthless waste products such as the kerf cut away from buns of polyimide foam during the foam manufacturing process can be converted and vastly upgraded into any of such an array of new articles of manufacture such as those just mentioned.

Abstract: A polyimide precursor mixture having a solids content of about 50 to about 77 (preferably about 65 to about 75) weight percent is subjected to a multistaged thermal treatment in which the precursor is heated to one or more temperatures sufficient to obtain a consolidated but friable cellular foam structure, and the resultant cellular foam structure is then subjected to one or more higher temperatures sufficient to cure the cellular material into a resilient polyimide foam. There is no need for use of time-consuming and expensive spray drying and microwave radiation apparatus.

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 improved microwave-based foaming processes. In one such process, 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. Mechanisms by which the shields function to provide the improvements of the process are discussed, and methods based thereon are set forth.

Abstract: By compressing and heat curing a non-resilient, non-flexible recurable material formed by subjecting cured polyimide foam to the action of pressurized steam, a wide variety of useful articles may be produced. These include tough, flame-resistant plastic films, sheets, panels, boards, and shapes in general; composites (both reinforced and unreinforced); and laminates and other articles in which separate shapes or parts are bonded together by a new type of tough, flame-resistant adhesive. Additionally, heretofore worthless waste products such as the kerf cut away from buns of polyimide foam during the foam manufacturing process can be converted and vastly upgraded into any of such an array of new articles of manufacture such as those just mentioned.

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: In a process for the production of cellular products comprising thermoplastic or rubber materials the blowing agents employed have the formula: ##STR1## wherein A represents NHX, NRR' or ORX represents H or a lower alkyl group,R represents a lower alkyl group, andR' represents a lower alkyl group.The novel blowing agents provide high gas yields and have high decomposition temperatures while forming only inert nitrogen gas. They are particularly suitable for the production of cellular products from high temperature thermoplastic materials such as polycarbonates.

Abstract: Cured polyimide foam is exposed to an atmosphere of steam at elevated temperature and pressure for a period of time sufficient to convert the foam into a non-flexible, non-resilient recurable cellular material. Preferably the process is conducted such that the cellular material is recurable to a flexible resilient foam having tensile strength properties similar to the tensile strength properties of the original cured polyimide foam subjected to the process. Before recuring, the non-flexible, non-resilient recurable cellular material may be shaped or contoured, and then recured. For example, by impressing shaped articles into the recurable material followed by recuring, shipping/storage containers for the articles are readily produced.

Abstract: This disclosure relates to a method for producing polyethylene open-cell foam materials, comprising a process step of pressurized heating at a temperature of 110.degree. to 135.degree. C. of a base compound consisting of polyethylene or a copolymer of polyethylene which has been compounded with an azodicarbonamide foaming agent and a bridging agent, in order to obtain a primary intermediate product with a cubical expansion coefficient of 1.0 to 2.0 times; a process step of heating the primary intermediate product under normal atmospheric pressure at a temperature of 150.degree..about.190.degree. C.

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 improved microwave-based foaming processes. In one such process, 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. Mechanisms by which the shields function to provide the improvements of the process are discussed, and methods based thereon are set forth.

Abstract: By compressing and heat curing a non-resilient, non-flexible recurable material formed by subjecting cured polyimide foam to the action of pressurized steam, a wide variety of useful articles may be produced. These include tough, flame-resistant plastic films, sheets, panels, boards, and shapes in general; composites (both reinforced and unreinforced); and laminates and other articles in which separate shapes or parts are bonded together by a new type of tough, flame-resistant adhesive. Additionally, heretofore worthless waste products such as the kerf cut away from buns of polyimide foam during the foam manufacturing process can be converted and vastly upgraded into any of such an array of new articles of manufacture such as those just mentioned.

Abstract: Low density rigid foamed polyphosphazene articles having excellent physical and flammability properties are made by masticating a mixture of high molecular weight linear polyphosphazene, a curing agent (e.g., sulfur), an accelerator, a blowing agent and optionally fillers, processing aids and the like to form a substantially homogeneous blend and then stopping the masticating, heating to pre-cure and then heating to activate the blowing agent and complete the cure thereby forming a flexible foamed polyphosphazene composite, forming the flexible foamed polyphosphazene composition into a shaped composition, and thereafter heating the flexible foamed shaped polyphosphazene composition at a temperature and for a length of time which causes the flexible foamed polyphosphazene composition to become a rigid foamed polyphosphazene composition of the same shape as the flexible foamed polyphosphazene composition.

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: A method of making thermal insulating products comprising porous, lightweight, high temperature resistant inorganic particles in a polyimide foam matrix and the product thereof. A polyimide precursor provided is mixed with about equal weight of flake-like porous inorganic particles to substantially uniformly coat the particles with powder. The mixture is placed in a mold and compressed slightly. The assembly is heated to the foaming temperature of the polyimide precursor for a period suitable to produce uniform foaming. Then the temperature is raised to the curing and crosslinking temperature of the precursor for a time period sufficient to produce complete cure. A high temperature and flame resistant, light weight, highly insulating product results. If desired, protective sheets of material may be bonded to selected product surfaces during or after the molding operation.

Abstract: A low density extruded structural foam of closed cell structure having good compressive strength comprising a engineered thermoplastic resin, alone, or containing a flame retarding agent and/or nucleating agent, optionally combined with a vinyl aromatic resin, and a blowing agent is produced by feeding said resin, or composition, into a primary extruder wherein mixing, adding a blowing agent which is essentially insoluble in the resin at room temperature but soluble in the melt and further mixing, then optionally passing the mixture to a second, cooling extruder, passing said extruded mixture through a die, then expanding and foaming said composition into a foam article.

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 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 mmicrowave-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 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: Thermosetting fluoropolymer foams are made by mixing fluid form thermosetting fluoropolymer components having a substantial fluorine content, placing the mixture in a pressure tight chamber, filling the chamber with a gas, at relatively low pressure, that is unreactive with the fluoropolymer components, allowing the mixture to gel, removing the gelled fluoropolymer from the chamber and thereafter heating the fluoropolymer at a relatively low temperature to simultaneously cure and foam the fluoropolymer. The resulting fluoropolymer product is closed celled with the cells storing the gas employed for foaming. The fluoropolymer resins employed may be any thermosetting fluoropolymer including fluoroepoxies, fluoropolyurethanes and fluoroacrylates.

Abstract: The present invention provides novel spherical grains of polyamino acid wh can be used as a filler in chromatography, cosmetic powder and the like. The spherical grains can be produced by a method which comprises the steps of preparing a solution of hydrophobic polyamino acid such as poly n-leucine dissolved in an organic solvent; adding the solution to an aqueous medium and agitating said medium so as to obtain a dispersion of the spherical grains of the polyamino acid dispersed in the aqueous medium while evaporating the organic solvent; and taking out the spherical grains of polyamino acid from the dispersion.

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: A polyamide powder consisting essentially of elementary porous particles having a "gypsum rose" structure and a process for preparing a polyamide powder comprising polymerizing by anionic polymerization lactam in a solvent medium in the presence of a catalyst, an activator, and at least one amide; one of which is N,N'-alkylene bisamide; said polymerization being initiated with said lactam and said amide used in an amount such that the solvent is in the supersaturated state at the polymerization initiation temperature.

Abstract: Disclosed herein are microporous polybenzimidazole articles prepared by the addition of a leachable additive to a polybenzimidazole polymer solution or dope and the subsequent leaching of the additive from the polybenzimidazole article. The microporous polybenzimidazole article may be formed into filaments or films. The micropores of the microporous polybenzimidazole article may be filled with an absorbent resin which will act to absorb chemicals or other harmful products. The microporous polybenzimidazole article with absorbent material may be formed into clothing which is highly resistant to both chemicals and heat.

Abstract: Process for the preparation of polycarbonates by reacting at least one epoxy compound with carbon dioxide at 40.degree. to 200.degree. C. and 2 to 40 bar in the presence of a catalytic amount of a double metal cyanide complex and(a) one or more salts composed of at least bivalent metal ions and metal-free anions having a solubility in water of at least 1 g/100 ml at 25.degree. C., and/or(b) one or more no-metal containing acids of which a 0.1 N solution in water at 25.degree. C. has a pH not exceeding 3.

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: Aliphatic polyamides are reacted on their surfaces with sulphuryl chloride, either neat or in solution in paraffins or cycloparaffins to give reactive intermediate whcih may convert into a support capable of reaction with antibodies or enzymes by providing covalent chemical links to which the antibodies or enzymes may be bound.

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: 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: 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: 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: The present invention relates to a process for molding a foamed article comprising mixing a polyphenylene sulfide resin with about 0.1 to 10% of an oligomeric sulfone carbonate as a foaming agent and with 0.1 to 2% of a basic catalyst at a temperature of about 150.degree. to 180.degree. C. and then heating the resulting mixture at a temperature of 280.degree.-350.degree. C. to affect a reaction mixture and introducing the reaction mixture into a suitable mold for producing a foamed article.

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 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: Novel polylactide composition containing segments of poly(R-lactide) interlocked with segments of poly(S-lactide).

Abstract: Semipermeable membranes with improved permeation flux are prepared by contacting a glassy polymer in the form of a hollow fiber or film with a solvent in which the polymer swells at conditions which permit the swelling solvent to diffuse into the glassy polymer and then stretching the swollen polymer in an amount sufficient to cause visible stress whitening.

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 are new poly(ester-ether-carbonates) which may be prepared by heating aromatic diol polycarbonates and poly(ester-carbonates) with ethylene carbonate, optionally in the presence of a suitable catalyst or promoter.

Abstract: Liquid, solventless, complex polymeric compositions are provided which thermoset at ambient temperatures through addition polymerization. In a preferred embodiment, a two component system includes a first component comprising amine or acrylate terminated polyurethanes, polyurethane-ureas or polyureas and a second component comprising di or polyacrylates. By adding an excess of acrylate, a one component system can be formed which thermosets when exposed to ultraviolet radiation.

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: Novel polylactide composition containing segments of poly(R-lactide) interlocked with segments of poly(S-lactide).

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: A gas-releasing composition of a t-alkylhydrazinium salt and/or a carbonylhydrazine and at least one compound selected from free radical forming sources, metal oxides, and sulfur and/or sulfur donor compounds wherein when sulfur and/or a sulfur donor compound is used, the composition will also contain one or more members selected from sulfur accelerators, metal oxides, and amino-alcohols. This novel gas-releasing composition permits the selectively tailoring of the gas evolution of a system in order to meet a wide range of specific application areas polymer characteristics and conditions over a wide temperature range.

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: Metal castings having reduced residual carbon ash and surface flaws are produced by an evaporative pattern casting process, in which an organic foam pattern is vaporized upon contact with a molten metal leaving a metal replica of the pattern. The organic foam used in this process comprises a polymer formed by polymerizing CO.sub.2 with one or more oxirane compounds.

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 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.