Blends of polybenzimidazoles and aromatic polyamides, aromatic polyamide-hydrazides or aromatic polyamides containing heterocyclic linkages

Abstract

A novel miscible blend of component polymers comprised of from about 5 weight percent to about 95 weight percent of a polybenzimidazole and from about 95 weight percent to about 5 weight percent of an aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages. Miscibility of the component polymers of the blend is indicated by infrared, X-Ray and Differential Scanning Calorimetry analyses and scanning electron photomicrographs. In a film or molded article of a blend mostly comprised of a polybenzimidazole, it is preferred that the aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages be present in the blend in an amount sufficient to result in a blend with improved tensile properties compared to the polybenzimidazole and that is more thermally processable than the polybenzimidazole. In a blend mostly comprised of an aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages, it is preferred that the polybenzimidazole be present in the blend in an amount sufficient to result in a blend with increased thermal stability and nonflammability compared to the aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages. The blends, particularly in the form of films or molded articles, may be post-treated with heat or sulfonating agent in order to minimize their shrinkage when subsequently subjected to heat and in order to increase their resistance to solvents and acids.

Dependencies are inferred from the claim text.