A NEW HIGH-PERFORMANCE THERMOPLASTIC POLYIMIDE AND ITS FIBER-REINFORCED COMPOSITES

A new high-performance thermoplastic polyimide has recently been synth esized from 3,3',4,4'-benzophenonecarboxylic dianhydride (BTDA) and 2, 2'-dimethyl-1,3-(4-aminophenoxy)propane (DMDA). It has been shown to p ossess good dimensional and thermal stability, as well as exhibiting e xcellent mechanical properties, in particular the extraordinary toughn ess of BTDA-DMDA with a fracture energy G(1C) value of 4.28 kJ m(-2), which exceeds that of other high-performance materials by about 100%. Clearly, this material has great potential as a matrix resin for high- temperature, high-performance composites. This report focuses on the s tudy of this polymer's structure, crystal morphology, crystal-amorphou s interface and relaxation processes in order to find the origin of th is unusually high toughness. In addition to this, we have also examine d the matrix/fiber interfaces of BTDA-DMDA-based carbon fiber and poly imide fiber-reinforced composites via their mechanical properties, and then their crystallization and relaxation behaviors.