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: 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 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 new type of aromatic polyamide powder including a large number of fine coalescible particles which have an average size of from 0.1 to 10 .mu.m, which include at least one aromatic amide polymer including 40 to 100 molar % of recurring m-phenylene isophthalamide units and 0 to 60 molar % of at least one other type of additional recurring aromatic amide units, for example, m-phenylene terephthalamide units, and which coalesce with each other to form porous agglomerates having an average size of from 10 to 400 .mu.m and a surface area of from 1 to 20 m.sup.2 /g, and can be compression molded, optionally in mixture with a reinforcing additive, for example, aromatic polyamide fibers having a length of 3 mm or less, at a temperature of 200.degree. to 400.degree. C. under a pressure of 300 to 1000 kg/cm.sup.2 for 20 minutes to 5 hours, to produce shaped articles having excellent mechanical properties and appearance.

Abstract: A new type of aromatic polyamide powder including a large number of fine coalescible paticles which have an average size of from 0.1 to 10 .mu.m, which include at least one aromatic amide polymer including 40 to 100 molar % of recurring m-phenylene isophthalamide units and 0 to 60 molar % of at least one other type of additional recurring aromatic amide units, for example, m-phenylene terephthalamide units, and which coalesce with each other to form porous agglomeraters having an average size of from 10 to 400 .mu.m and a surface area of from 1 to 20 m.sup.2 /g, and can be compression molded, optionally in mixture with a reinforcing additive, for example, aromatic polyamide fibers having a length of 3 mm or less, at a temperature of 200.degree. to 400.degree. C. under a pressure of 300 to 1000 kg/cm.sup.2 for 20 minutes to 5 hours, to produce shaped articles having excellent mechanical properties and appearance.

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 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 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: 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: 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: 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 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 butadiene-nitrile copolymer. The polyimides of the invention are particularly useful in the preparation of flexible foams.

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: 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: Methods of making modified polyimide/polyimide-amide foams having selected compressive resistance and density characteristics and the resulting compositions. A suitable aromatic dianhydride is mixed with a suitable oxoimine and alcohol, which initially is believed to form a monoimide which is substantially/simultaneously esterified by the alcohol. To this mixture is added a suitable diamine to produce a polyimide forming material. 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. Within the mole ratio range of oxoimine to dianhydride of about 1.5:1 to about 0.

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: A method of preparing a polyimide foam which includes the steps of: preparing, foaming, and curing a precursor containing at least one alkyl ester of 3,3'4,4'-benzophenonetetracarboxylic acid; a meta- or para-substituted aromatic diamine; a heterocyclic diamine; an aliphatic diamine; and a solid blowing agent. The blowing agent is added to said precursor in a concentration which is sufficient to effect at least one of the following attributes of the foam: cell size, proportion of open cells, cell density, and indentation load deflection.

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: Methods of converting essentially unpolymerized precursors into polyimides in which the precursors are exposed to microwave radiation. Preheating, thermal post-curing, and other techniques may be employed to promote the development of optimum properties; and reinforcements can be employed to impart strength and rigidity to the final product. Also disclosed are processes for making various composite artifacts in which non-polymeric precursors are converted to polyimides by using the techniques described above.

Abstract: High performance foams comprised of thermotropic liquid crystal polymers are provided. The lightweight rigid foams exhibit a combination of excellent properties including enhanced mechanical properties such as high strength to weight ratio, high flame and thermal stability, and excellent solvent resistance. The foams fabricated from such polymers have significantly reduced anisotropy compared to unfoamed polymers. The transverse mechanical properties are enhanced by foaming relative to the percentage density reduction due to the foaming. The physical properties of the foams are further enhanced by heat treatment as the core of foams of thermotropic liquid crystal polymers consists of highly oriented cell walls which can exhibit greater enhancement upon heat treatment than is exhibited by the core of the unfoamed polymer.

Abstract: High performance foams comprised of certain thermotropic liquid crystal polymers are provided. Such thermotropic liquid crystal polymers comprise not less than about 10 mole percent of recurring 6-oxy-2-naphthoyl moieties. The lightweight rigid foams exhibit a combination of excellent properties including enhanced mechanical properties such as high strength to weight ratio, high flame and thermal stability, and excellent solvent resistance. The foams fabricated from such polymers have significantly reduced anisotropy compared to unfoamed articles of the same polymers.

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

Abstract: Methods of converting essentially unpolymerized precursors into polyimides in which the precursors are exposed to microwave radiation. Preheating, thermal post-curing, and other techniques may be employed to promote the development of optimum properties; and reinforcements can be employed to impart strength and rigidity to the final product. Also disclosed are processes for making various composite artifacts in which non-polymeric precursors are converted to polyimides by using the techniques described above.

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: 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: Terpolyimides prepared from tetracarboxylic acid esters and combinations of heterocyclic, aromatic, and aliphatic diamines and artifacts composed of those terpolymers. Precursors, and methods of converting them to the corresponding terpolymers.

Abstract: Closed cell polyimide foams. Methods of making such foams from precursors derived from a benzophenonetetracarboxylic acid diester and a mixture of diamines in which the precursor is molded to shape and cured, hydrated, and heated until a porous, closed cell structure develops.

Abstract: Terpolyimides prepared from tetracarboxylic acid esters and combinations of heterocyclic, aromatic, and aliphatic diamines and artifacts composed of those terpolymers. Precursors, and methods of converting them to the corresponding terpolymers.

Abstract: Terpolyimides prepared from tetracarboxylic acid esters and combinations of heterocyclic, aromatic, and aliphatic diamines and artifacts composed of those terpolymers. Precursors, and methods of converting them to the corresponding terpolymers.

Abstract: Terpolyimides prepared from tetracarboxylic acid esters and combinations of heterocyclic, aromatic, and aliphatic diamines and artifacts composed of those terpolymers. Precursors, and methods of converting them to the corresponding terpolymers.

Abstract: Methods of converting essentially unpolymerized precursors into polyimides in which the precursors are exposed to microwave radiation. Preheating, thermal post-curing, and other techniques may be employed to promote the development of optimum properties; and reinforcements can be employed to impart strength and rigidity to the final product. Also disclosed are processes for making various composite artifacts in which non-polymeric precursors are converted to polyimides by using the techniques described above.

Abstract: Methods of preparing polyimides and polyimide precursors from liquid resins containing tetracarboxylic acid esters and primary diamines which involve spray drying the resin.

Abstract: Polyimide foams derived from mixtures of aromatic diamines and partial esters of a benzophenonetetracarboxylic acid. The precursors are converted into polyimide foams by the application of heat; and the foams are then compressed, yielding dense, rigid, and structurally strong, intumescent 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.