Processable Polyimides

Abstract

1. Introduction Since the discovery of polyimides in the early 1960's engineers have sought to prepare composite parts where maximum use could be made of their exciting properties. Typical attributes include: high heat resistance (500°F and up), good mechanical properties, wear resistance, low friction, chemical inertness, low outgassing, radiation and cryogenic temperature stability, and inherent non-flammability. These attempts were frequently thwarted, however, by discouraging resin processability. Indeed, extensive and complex cure and post-bake cycles were required and strict adherence to fabrication parameters was demanded. The historically-first condensation polyimides have recently been complemented by a second class of resins - addition-type polyimides. KINEL compounds and KERIMID 601 laminating resin are members of this new family of polyimides. Chemically they are designated polyaminobismaleimides (PABMs). Condensation polyimides are predicated on the reaction of an aromatic diamine with an aromatic dianhydride. The resultant, tractable polyamic acid is converted during cure to the infusible, insoluble