Abstract: Flame-retardant blends are provided comprising a particular type of aromatic-aliphatic copolyamide and a flame-retardant amount of an oligomeric or polymeric halogenated aromatic polycarbonate.The blends are characterized by being transparent and meeting the V-O rating when tested in accordance with the Underwriters Laboratories UL-94 vertical burn test.

Abstract: Blends are provided of (a) certain aromatic-aliphatic polyamides and (b) an impact resistance-enhancing amount of a particulate rubbery impact modifier.

Abstract: A process is described for the conversion of solid polymers to powders in which the particles are substantially spherical and uniform in size. The polymer is dissolved in an aprotic solvent which is at least partially miscible with water but immiscible with mineral oil, the resulting solution is emulsified in mineral oil, and a minor amount of water or a glycol is added with agitation. The powdered polymer separates and is isolated by filtration, centrifugation and the like. Alternatively, when the precipitant is a glycol having a boiling point higher than the aprotic solvent in which the polymer is initially dissolved, the powdered polymer is isolated by filtration, centrifugation and the like after first removing the aprotic solvent and glycol by distillation. The process is applicable to a wide variety of polymers (polyimide, polyamides, polyamideimides, polyurethanes) which are soluble in aprotic solvents.

Abstract: Syntactic foams are described which consist of a spherical filler (microballoons, microspheres) embedded in a polyimide which is characterized by solubility in polar organic solvents and by thermoplasticity. These syntactic foams possess high structural strength, high resistance to deformation upon exposure to heat, and the ability to be subjected to further molding, e.g. for shaping and/or increase in density, if desired. These properties render the materials useful for a wide variety of structural and insulative applications e.g. in the preparation of mechanical parts and, using microballoons, lightweight, substantially non-burning, structural panels.