Fibers and fibrets from blends of polybezimidazoles and aromatic polyamides, aromatic polyamide-hydrazides or aromatic polyamides containing heterocyclic linkages

Abstract

Fibers and fibrets of a novel miscible blend of component polymers comprising 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 electron photomicrographs. In fibers or fibrets 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 yield a blend with improved tensile properties compared to the polybenzimidazole and more thermally processable than the polybenzimidazole. The fibers or fibrets of the blend have a lower moisture regain than polybenzimidazole fibers or fibrets. In fibers or fibrets of 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 yield a blend with increased thermal stability and nonflammability compared to the aromatic polyamide, aromatic polyamide-hydrazide or aromatic polyamide containing heterocyclic linkages. The fibers or fibrets may be post-treated with heat or sulfuric acid in order to minimize their shrinkage when they are subsequently subjected to heat and in order to increase their resistance to solvents and acid.

Dependencies are inferred from the claim text.