Preparation and fabrication of aromatic polyimides

Abstract Aromatic polyimides were prepared from pyromellitic dianhydride and a number of aromatic diamines. The effect of certain variables on the polymerization to, and the degradation of, the intermediate polypyromellitamic acids was studied, and a previously unrecorded reaction intermediate was isolated and identified. From these studies the conditions necessary to obtain high molecular weights were defined. Techniques were developed for the fabrication of satisfactory films and moldings.