Composites of aromatic polybenzimidazoles and polyarylates and process for their preparation.

摘要

A composite comprising a polyarylate or an aromatic polybenzimidazole article and a coating on at least one surface of the article comprised of a blend of from about 5 to about 95 weight percent of a polyarylate and from about 95 to about 5 weight percent of an aromatic polybenzimidazole. A process for preparing the composites comprises dissolving in a mutual solvent from about 5 to about 95 weight percent of the aromatic polybenzimidazole to about 95 to about 5 weight percent of the polyarylate, based on the total weight of those polymers, heating a polyarylate or aromatic polybenzimidazole article to a surface temperature over 100 DEG C., e.g., from about 120 DEG C. to about 180 DEG C., and then coating the polyarylate or aromatic polybenzimidazole article with the solution and subsequently evaporating the solvent, thereby producing a dried coating of a blend of a polyarylate and an aromatic polybenzimidazole on at least one surface of the article. The composites, particularly in the form of films, fibers or fibrets, may be post-treated with heat or sulfuric acid in order to minimize their shrinkage when subsequently subjected to heat and in order to increase their resistance to solvents and acid.