Polyimides from dianhydrides and bis(p-aminophenyl) alkane diamines. I

Polyimides were synthesized from pyromellitic dianhydride (PMDA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and three different diamines with the following general structure: where R is ethyl, propyl, or isobutyl. The poly(amic acids) obtained had inherent viscosities ranging from 0.30 to 0.93 and were thermally/chemically converted to polyimides. The thermal stability of the polyimides was evaluated by using dynamic thermogravimetric analysis in air. Physical and thermal properties of these polyimides were compared with that obtained by reacting 2,2‐bis(4‐aminophenyl) propane and PMDA/BTDA.