Thermal stabilization of polypyromellitimide films

The paper is devoted to the modification of the polyimide based on pyromellitic dianhydride and 4,4'-diaminodiphenyloxide with phosphoric and boric anhydrides. 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 expenditures while, at the same time, preserving the film-forming ability and mechanical properties of the polyimide.