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, prior to the application of the microwave radiation, the body of polyimide precursor is compressed at a pressure that will reduce the bulk volume of the precursor and heated to a temperature below that at which any substantial foaming occurs. to accomplish the foaming, one further embodiment of the invention employs microwave radiation directed upon the top, sides and ends of the body of above-treated polyimide precursor and of the foam structure as it is developing maintaining the developing foam under a substantially vapor-impermeable microwave compatible shroud. The extent to which the microwave 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: Foamed thermoplastic blends of Nylon 6,I/T and polycarbonate resin are provided which exhibit good chemical resistance. The foamed blends are useful for making foamed articles such as chemically resistant foamed sheet.

Abstract: A method of making polyetherimide foam precursors and flexible polyetherimide foams having improved specific tensile strength, resistance to high temperatures and flame, low density and flexibility at both high and cryogenic temperatures. 4,4'-oxydiphthalic anhydride (ODPA) is reacted with an alcohol to produce a diester, which is then reacted with a suitable monomeric polyamine such as meta phenylene diamine to produce a precursor. This material is dried to a solid block or powder. Upon heating, foaming occurs, resulting in a fine celled white friable mass. The foam is cured by heating for a suitable period and is ready for use.

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: A copolyimide foam comprising the reaction product of one or more of an aromatic tetracarboxylic acid and a compound of the formula: ##STR1## where x is an integer from 1 to 12 and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same or different and are hydrogen or C.sub.1 to C.sub.6 linear or branched alkyl a mixture thereof with two or more diamines at least one of which being a heterocyclic diamine having a nitrogen atom in the ring and the other being a para- or meta-substituted aromatic diamine free of aliphatic substitution.Processes for producing the above copolyimide foam are also disclosed.

Abstract: A process for producing cellular foamed articles from high temperature engineering polymers wherein polymeric blowing agents are utilized to expand the polymers. The process comprises mixing a first polymer capable of being foamed with a second polymer comprising at least one poly(alkylene carbonate) to provide a polymer blend; heating the polymer blend to a temperature sufficient to melt the polymer to be foamed and to decompose the second polymer to form gas inclusions within the first polymer; expanding the melted first polymer containing the gas inclusions to form a foamed article; and cooling the foamed article to a temperature below the melting or softening point of the foamed article. Polymers which may be foamed according to the process include those polymers which can tolerate processing temperatures in excess of 260.degree. C.

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: A polyamide dyed with a reactive dye capable of absorbing incident light of the excitation waveband of a fluorophore or light of the emission waveband of the polyamide is provided for use in assays in which the presence or quantity of an analyte is being detected by fluorescence as a result of excitation of a fluorescent material at an excitation waveband of light and in which the excitation waveband impinges upon the polyamide.

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: 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: 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 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: 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: Open-cell structures are filled with polyimide foam formed in place by the use of a foam precursor in powdered form comprised of a combination of (a) the reaction product of an excess of organic polyisocyanate and a member selected from the group consisting of furfuryl alcohol and condensation products thereof, and (b) an organic polycarboxylic compound containing two carboxylic anhydride groups. The precursor is prepared by combining the species under conditions which favor the reaction of the furfuryl alcohol with the polyisocyanate, but not the polyimide-forming reaction. The polyimide-forming reaction itself is then performed by adding preselected amounts of the powdered precursor, depending on the desired ultimate density of the foam, to each cell of the open-cell structure, then heating to initiate the polyimide reaction, and permitting the carbon dioxide generated by the reaction to escape while confining the resulting foam to the cells.

Abstract: Open-cell structures are filled with polyimide foam formed in place by the use of a foam precursor in powdered form comprised of a combination of (a) the reaction product of an excess of organic polyisocyanate and a member selected from the group consisting of furfuryl alcohol and condensation products thereof, and (b) an organic polycarboxylic compound containing two carboxylic anhydride groups. The precursor is prepared by combining the species under conditions which favor the reaction of the furfuryl alcohol with the polyisocyanate, but not the polyimide-forming reaction. The polyimide-forming reaction itself is then performed by adding preselected amounts of the powdered precursor, depending on the desired ultimate density of the foam, to each cell of the open-cell structure, then heating to initiate the polyimide reaction, and permitting the carbon dioxide generated by the reaction to escape while confining the resulting foam to the cells.

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: Open-cell structures are filled with polyimide foam formed in place by the use of a foam precursor in powdered form comprised of a combination of (a) the reaction product of an excess of organic polyisocyanate and a member selected from the group consisting of furfuryl alcohol and condensation products thereof, and (b) an organic polycarboxylic compound containing two carboxylic anhydride groups. The precursor is prepared by combining the species under conditions which favor the reaction of the furfuryl alcohol with the polyisocyanate, but not the polyimide-forming reaction. The polyimide-forming reaction itself is then performed by adding preselected amounts of the powdered precursor, depending on the desired ultimate density of the foam, to each cell of the open-cell structure, then heating to initiate the polyimide reaction, and permitting the carbon dioxide generated by the reaction to escape while confining the resulting foam to the cells.

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 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: 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: 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 polymeric porous membrane having a matrix made from an aliphatic thermoplastic polyamide or from an aliphatic thermoplastic polyamide/polyimide copolymer which has both relatively non-crystalline and relatively crystalline portions. The pores in the membrane are defined by spaces between the relatively crystalline portions and at least some of the relatively crystalline portions are linked together by the reaction of a bis-aldehyde with the membrane matrix.

Abstract: Composite materials useful as hard tissue prosthetics comprising synthetic biodegradable polymers and unsintered calcium phosphate biomaterials optionally porositized by pore-forming agents are described. The composite materials may be ground and blended with a compatible water soluble pore-forming agent and then molded to form dense, shaped objects which may be made porous by leaching out said water soluble pore-forming agent. The composites may be used as hard tissue prosthetics either alone or in conjunction with conventional prostheses.

Abstract: An in situ polymerization process is disclosed whereby an .alpha.-amino acid N-carboxyanhydride is blended intimately and efficiently with one or more calcium phosphate biomaterials. The polymerization proceeds at ambient temperature and pressure without the need for initiators or surface modification of the calcium phosphate biomaterials. The resulting composite material may subsequently be ground and blended with a compatible water soluble pore-forming agent and then molded to form dense, shaped objects which may be made porous be leaching out said water soluble pore-forming agent. The resulting shaped objects may then be used as hard tissue prosthetics either alone or in conjunction with conventional prostheses.

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: Novel amorphous polyimides are provided which are formed by the polymerization of bismaleimides with sydnones wherein carbon dioxide is evolved.The polyimides are readily soluble in dipolar aprotic solvents and are further characterized by high temperature stability to at least 300.degree. C.The polymers find particular utility in the form of films and solutions useful for wire enamel and electrical coatings.

Abstract: Methods of producing high molecular weight polyamide-imide foams having superior flame resistance and the foam products produced thereby. Initially, an imidocarboxylic acid is prepared by reacting a suitable oxoimine with a suitable cyclic dianhydride at a temperature of from about 25.degree. to 250.degree. C. in the presence of a solvent or by melt condensation without a solvent. The ratio of oxoimine to dianhydride may be varied to vary the number of imido groups in the final monomer. The imidocarboxylic acid monomer is reacted with an organic isocyanate in the presence of a suitable tertiary diamine catalyst and water to produce the polyamide-imide foam. The material foams spontaneously at room temperature. The reaction may be accelerated by heat or the addition of suitable metal salts. Additives, such as surfactants, flame retardants, fillers, etc., may be added if desired.

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: Methods of producing high molecular weight polyamide-imide foams having superior flame resistance and the foam products produced thereby. Initially, an imidocarboxylic acid is prepared by reacting a suitable oxoimine with a suitable cyclic dianhydride at a temperature of from about 25.degree. to 250.degree. C. in the presence of a solvent or by melt condensation without a solvent. The ratio of oxoimine to dianhydride may be varied to vary the number of imido groups in the final monomer. The imidocarboxylic acid monomer is reacted with an organic isocyanate in the presence of a suitable tertiary diamine catalyst and water to produce the polyamide-imide foam. The material foams spontaneously at room temperature. The reaction may be accelerated by heat or the addition of suitable metal salts. Additives, such as surfactants, flame retardants, fillers, etc., may be added if desired.

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: A nylon foam product produced by frothing in an intensive mixer a reaction mixture of catalyst, caprolactam and polyol prepolymer in the presence of a surfactant and gaseous frothing agent.

Abstract: Spherical porous polyimide powder having an average particle diameter of 1 to 20 .mu.m which is infusible and insoluble in organic solvents is produced by polymerizing an aromatic tetracarboxylic acid dianhydride and an aromatic polyisocyanate in an organic solvent at a temperature of 100.degree. to 200.degree. C. and in the presence of a tertiary amine catalyst to form polyimide particles in the form of slurry, filtering or centrifuging said polyimide particles, and washing the resulting polyimide particles with an organic solvent.

Abstract: A nylon foam product produced by frothing in an intensive mixer a reaction mixture of catalyst, caprolactam and polyol prepolymer in the presence of a surfactant and gaseous frothing agent.

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: The present invention comprises a new phenolic-aldehyde based resinous, thermosetting polyol and a method for its production. According to the invention, phenol is condensed using acid catalysis, under freely evaporative atmospheric conditions with a molar excess of aldehyde, in the presence of polyhydroxyl component.

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: High density structural ("blocking") materials composed of a polyimide filled with glass microballoons. Structural components such as panels which have integral edgings and/or other parts made of the high density materials.

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.