Abstract: Polyimide foam of desired density is produced by adding to a polyimide precursor comprising carboxylic and diamine components at least one foam-enhancing polar, protic additive of the formula ROH, where R is hydrogen, or C.sub.1 to C.sub.12 linear or branched alkyl or cycloalkyl, unsubstituted or substituted with halo, aryl, alkoxy or hydroxy, and heating the resultant slurry to a temperature that does not exceed about 105.degree. C. to form a homogeneous melt. When heated to a higher temperature the melt foams and cures. The density of the foam is affected by the amount of foam-enhancing additive which is utilized.

Abstract: A process for purifying propylene oxide containing an unacceptable quantity of poly(propylene oxide) contaminant having a molecular weight of at least about 50,000, which comprises contacting the so-contaminated propylene oxide with a quantity of a substantially non-calcined diatomaceous earth for a time and under conditions sufficient to reduce the amount of such contaminant in such propylene oxide to acceptable levels, and recovering the purified propylene oxide product. Also, processes for making polyether polyols from such purified propylene oxide products, and for making high resilient flexible polyurethane foams from such polyols.

Abstract: A porous hollow fiber of polysulfone suitable for use in filtration such as microfiltration and having a prolonged life, the hollow fiber having an inner surface of a network structure such that approximately circular openings having a minor axial length of 0.1 to 10 .mu.m are present in proximity to each other at intervals of not more than the average minor axial length of the openings, thus providing a surface fraction of openings of 50 to 90%, and/or an outer surface of a structure such that the outer surface region has undergone fibrillation to a high degree to form fibrils oriented in the fiber axial direction at intervals of 0.2 to 3 .mu.m, thus providing a surface fraction of openings of at least 50%. The hollow fiber is prepared by a process characterized in that a polymer substance having an extremely high molecular weight such as polyethylene glycol and polyvinyl pyrrolidone is added to the spinning solution of polysulfone, thereby improving the spinnability.

Abstract: The invention is directed to an unfoamed foil of at least one thermoplastic resin, said foil being capable of serving as an adhesive when softened and having included therein at least one blowing agent, and to the use thereof in preparing laminates.

Abstract: The present invention is directed to foams produced from poly(aryl ethers) and mixtures of poly(aryl ethers) with various non-poly(aryl ether) polymers. These foams are produced using aqueous blowing agents comprising water as the only blowing agent, or mixtures of water with another blowing agent material.

Abstract: Environmentally benign closed cell compositions made by foaming star-shaped polymers with a plurality of poly(hydroxy acid) chains attached to a central polyfunctional compound having a plurality of hydroxyl and/or amino groups.

Abstract: The odor of blends of polyphenylene ether resin, alone, or in combination with a polystyrene resin or a high impact polystyrene is improved by including a carboxylic acid, and acid anhydride or mixture thereof in the compositions.

Abstract: The present invention is directed to foams produced from poly(aryl ethers) and mixtures of poly(aryl ethers) with various non-poly(aryl ether) polymers. These foams are produced using aqueous blowing agents comprising water as the only blowing agent, or mixtures of water with another blowing agent material.

Abstract: A process for forming polymer powders by dissolving one or more polymers in a suitable solvent, followed by atomizing the solution into a droplet atmosphere of a non-solvent to precipitate polymer particles. The particles are separated from the non-solvent, washed and dried to produce a powder with a rounded particle morphology, high internal porosity and surface area, and high apparent density.Polymer powders with these properties can be pressed to dense shaped articles suitable for sintering in automated presses because the powders have good low and compressibility characteristics. The process if particularly useful when applied to soluble polymners that are not readily shaped by melt processing means.

Abstract: Closed cell rigid polyhydroxy acid resin compositions foamed with environmentally benign, which compositions are degradable and cause minimal environmental impact when discarded.

Abstract: A method is provided for recovering poly(arylene sulfide) polymers characterized by low ash and oligomer concentrations and having a larger particle size, which method comprises, during recovery, adding or maintaining a sufficient amount of a polar organic compound to the reaction mixture immediately after solidifying the poly(arylene sulfide) polymer.

Abstract: The invention relates to the use of polyarylene sulphides (PAS), preferably polyphenylene sulphide (PPS) for the preparation of a structural foam, a process for the production of this foam, and mouldings obtainable by this process.

Abstract: A slurry is produced by adding to a polyimide precursor comprising carboxylic and diamine components at least one foam-enhancing polar, protic additive of the formula ROH, where R is hydrogen, or C.sub.1 to C.sub.12 linear or branched alkyl or cycloalkyl, affording a slurry. The slurry is then brought to a temperature in the range of about 40.degree. C. to about 105.degree. C., producing a homogeneous, transparent solution, opaque suspension, or melt. When heated to a higher temperature the melt foams and cures.

Abstract: The invention relates to the use of polyarylene sulphides (PAS), preferably polyphenylene sulphide (PPS) for the preparation of a structrual foam, a process for the production of this foam, and moldings obtainable by this process.

Abstract: Polyimide foam of desired density is produced by adding to a polyimide precursor comprising carboxylic and diamine components at least one foam-enhancing polar, protic additive of the formula ROH, where R is hydrogen, or C.sub.1 to C.sub.12 linear or branched alkyl or cycloalkyl, unsubstituted or substituted with halo, aryl, alkoxy or hydroxy, and heating the resultant slurry to a temperature that does not exceed about 105.degree. C. to form a homogeneous melt. When heated to a higher temperature the melt foams and cures. The density of the foam is affected by the amount of foam-enhancing additive which is utilized.

Abstract: Aromatic copolyamides are described which are soluble in organic polyamide solvents and contain at least 95 mol % of repeating structural units of the formulae ##STR1## and up to 5 mol % of structural units E and/or F containing m-bonds and being derived from aromatic dicarboxylic acids (E') and/or aromatic diamines (F'), the sums of the molar proportions of structural units A+E and the molar proportions of structural units B+C+D+F being essentially the same. In these formulae, --Ar-- is a divalent aromatic radical whose valence bonds are in the para or comparable coaxial or parallel position, --R is hydrogen, lower alkyl radicals, lower alkoxy radicals or halogen, and R' is a direct bond, a polymethylene chain of 2 to 6 carbon atoms, --O--, --S--, --CO-- or --SO.sub.2 --, or a group of the formula --O--Ar'--O--, in which Ar' has the same meanings as Ar.

Abstract: A process for the preparation of expandable granules based on polyaryl ether sulfones and/or polyether imides, containing from 5 to 20% by weight of a physical blowing agent, the blowing agent and the polymers being mixed in an extruder and subsequently extruded directly into a medium at less than 40.degree. C., and a process for the production of foams from expandable granules based on polyaryl ether sulfones and/or polyether imides, containing from 5 to 20% by weight of a physical blowing agent, the granules being press molded at from 120.degree. to 250.degree. C. and at a pressure of from 5 to 30 bar to form a sheet, and the sheet being subsequently foamed by reducing the pressure, are described.

Abstract: A melamine preparation consisting of 80 to 99.9% by weight of melamine having an average particle size of 0.01 to 0.1 mm and 0.1 to 20% by weight of urea, thiourea, biuret or urea or thiourea substituted by lower alkyl groups and a stable dispersion in polyether polyols prepared therefrom, which is used for the preparation of flame-resistant polyurethane foams.

Abstract: Foams of density 0.1 to 1.0 g/cm.sup.3 based on aromatic polyether ketones and other thermoplastic polymers having a high melting point are obtained by melting an intimate mixture of the polymer and from 0.5 to 10% by weight of an aliphatic or aromatic dicarboxylic acid or polycarboxylic acid which suffers a weight loss of 50% or more with elimination of gaseous decomposition products on heating to from 130 to 300.degree. C., and simultaneously cooling and molding the melt.

Abstract: The disclosed invention is directed to polycyanoarylether membranes. These membranes are formed by reacting an aromatic diol with a dihalobenzonitrile or dinitrobenzonitrile in the presence of a base and a polar, aprotic solvent. These membranes can be provided as either homopolymers or copolymers.

Abstract: Polyimide foam of desired density is produced by adding to a polyimide precursor comprising carboxylic and diamine components at least one foam-enhancing polar, protic additive of the formula ROH, where R is hydrogen, or C.sub.1 to C.sub.12 linear or branched alkyl or cycloalkyl, unsubstituted or substituted with halo, aryl, alkoxy or hydroxy, and heating the resultant slurry to a temperature that does not exceed about 105.degree. C. to form a homogeneous melt. When heated to a higher temperature the melt foams and cures. The density of the foam is affected by the amount of foam-enhancing additive which is utilized.

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: A method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided non-metallic inorganic particles which are gel forming and insoluble in water and polar organic liquids into the foam cells. A stable liquid suspension or gel, preferably aqueous is prepared using these particles. An opacifier such as finely divided titanium dioxide or tin oxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles and further improves the flame resistance.

Abstract: Discrete, non-agglomerating particles of polyalkylene carbonate are produced by solvent/non-solvent precipitation using certain solvent/non-solvent systems. The free-flowing particles obtained are from 30 to 3000 microns in diameter and are suitable for use in a variety of applications, particularly the preparation of foamed articles.

Abstract: Expanded material obtained by heating a composition comprising at least one hermosetting nadimide resin, said heating being performed at a temperature and during a period which are sufficient to cause the expansion of said composition by release of cyclopentadiene. A nadimide resin of the polyimide type and having a number average molecular weight of 600 to 10,000 is preferably used. The composition further comprises preferably 1% to 50% by weight of a linear, preferably thermostable polymer.

Abstract: Moldable shrunken foam beads comprising a foamable thermoplastic polymer, preferably a silane-crosslinked polyolefin foam, are produced by mixing a composition comprising a silane-modified polyolefin (such as a silane-grafted polyethylene) and a silanol condensation catalyst in an extruder to produce a melt, then projecting a blowing agent into the melt at a rate effective to produce a desired foam density in the extrudate; extruding and cutting the melt to form foam beads; allowing the beads to shrink; and exposing the foam beads to moisture to produce silane crosslinking of the polyolefin foam. In certain other embodiments the crosslinking of the thermoplastic polymer can be omitted, and/or shrinkage of the beads produced by vacuum treatment.

Abstract: An improved process for producing sulfur-cured polyphosphazene foams is disclosed. The process comprises foaming more than one storable, stable accelerator base composition comprising the sulfur curing agent, a phosphazene oil and a polyphosphazene. A masterbatch of the same or similar polyphosphazene is made by mixing together a hydrated filler, processing aids and phosphazene oil. The matchbatch and accelerator base composition are then blended and foamed and cured.

Abstract: A modified poly(2,6-dimethyl-p-oxyphenylene) with a glass transition temperature in the range of 180.degree.-220.degree. C. is described in which on the average between 10 and 60% of the macromolecules carry:a) an ##STR1## unit; or b) an ##STR2## unit. Said modified poly(2,6-dimethyl-p-oxyphenylene) is useful as a material in the preparation of flat membranes, in particular asymmetric membrane, for gas separation.

Abstract: The present invention is directed to foams produced from sulfone polymers and mixtures of sulfone polymers with various non-sulfone polymers. These foams are produced using aqueous blowing agents comprising water as the only blowing agent, or mixtures of water with another blowing agent material.

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 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 hole repair method and composition suitable for mufflers, and engine exhaust systems, and any situation where high temperature resistance is needed. A putty like mass of polyimide resin and from 28% to 35% of low boiling alcohol is used to fill the hole, then foamed by heating into a mechanically seated and adherent plug which is high temperature resistant and securely in place.

Abstract: A method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided metal oxide particles into the foam cells. A stable water suspension or gel is prepared using particles of metal oxides, such as aluminum oxide and silicon dioxide. An opacifier such as titanium dioxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the metal oxide particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles.

Abstract: A method of manufacturing lightweight shapes from polyimide foam in which density discontinuities such as cavities, varying cell size, or swirl marks are substantially eliminated. A block or bun of polyimide foam is prepared in a conventional manner which results in a high density rind and other discontinuities. The foam is chopped into fine flakes in a chopper with a continuous flow of air to prevent electrostatic attachment of the flakes to the chopper and ducting. The flakes are mixed with a quantity of polyimide precursor and then heated to cause the precursor to bond the flakes into a uniform mass having highly uniform and predictable density. This is a very economical process since portions of the original bun may be used which would ordinarily be discarded. An alternative method is described whereby the flakes can be bonded together by using the precursor in the form of a partially cured foam either as a binder, or by making the flakes of partially cured foam.

Abstract: Thermoplastic polyimide foams are provided which essentially consist of recurring units represented by the formula (I): ##STR1## wherein X is a bond, divalent hydrocarbon radical having from 1 to 10 carbon atoms etc. and R is an aliphatic radical having 2 or more carbon atoms, cycloaliphatic radical etc.The foams have an apparent density of from 0.02 to 0.2 g/cc, average cell diameter of 0.1 to 1 mm and a closed cell content of 50% or more.

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 powdered 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 method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided non-metallic inorganic particles which are gel forming and insoluble in water and polar organic liquids into the foam cells. A stable liquid suspension or gel, preferably aqueous is prepared using these particles. An opacifier such as finely divided titanium dioxide or tin oxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles and further improves the flame resistance.

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: 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: 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: 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: 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 method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided metal oxide particles into the foam cells. A stable water suspension or gel is prepared using particles of metal oxides, such as aluminum oxide and silicon dioxide. An opacifier such as titanium dioxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the metal oxide particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles.

Abstract: A hole repair method and composition suitable for mufflers, and engine exhaust systems, and any situation where high temperature resistance is needed. A putty like mass of polyimide resin and from 28% to 35% of low boiling alcohol is used to fill the hole, then foamed by heating into a mechnically seated and adherent plug which is high temperature resistant and securely in place.

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 method of manufacturing lightweight shapes from polyimide foam in which density discontinuities such as cavities, varying cell size, or swirl marks are substantially eliminated. A block or bun of polyimide foam is prepared in a conventional manner which results in a high density rind and other discontinuities. The foam is chopped into fine flakes in a chopper with a continuous flow of air to prevent electrostatic attachment of the flakes to the chopper and ducting. The flakes are mixed with a quantity of polyimide precursor and then heated to cause the precursor to bond the flakes into a uniform mass having highly uniform and predictable density. This is a very economical process since portions of the original bun may be used which would ordinarily be discarded. An alternative method is described whereby the flakes can be bonded together by using the precursor in the form of a partially cured foam either as a binder, or by making the flakes of partially cured foam.

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 powdered 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 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 powdered 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 product uniform foaming. Then the temperature is raised to the curing and crosslinking temperature of the precursor for a time period sufficient to product 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: 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.