Thermal stabilization of polypyromellitimide films

The paper is devoted to the modification of the polyimide based on pyromell itic dianhydride and 4,4'-diaminodiphenyloxide with phosphoric and boric an hydrides. It is demonstrated that, due to the use of phosphorus- and boron- containing polyamidoacid compositions for casting the polyimide films, one can significantly increase their heat resistance without substantial expend itures while, at the same time, preserving the film-forming ability and mec hanical properties of the polyimide.