The development of processable, fully imidized, polyimides for high-temperature applications

Abstract

Novel end-capped, fully imidized polyimides have been developed as potential high-performance matrix materials for advanced composites. This study describes the synthetic development of norbornene-capped oligomers, subsequent screening of neat resin mechanical and thermo-oxidative properties and, finally, composite property evaluation. It is shown that these soluble reactive oligomers can be prepared reproducibly and give crosslinked networks that have mechanical properties more typical of thermoplastics, as well as good hot/wet and thermo-oxidative stability. Composites were prepared using a cure cycle more characteristic of thermosetting-type polyimides and it was demonstrated that fully imidized polyimides allow low-void-content laminate manufacture via autoclave processing. The evolution of imidization volatiles, which are generated using the more common PMR- and polyamic-acid-type systems, is averted using these reactive oligomers.