IM7 LARC(TM)-IAX POLYIMIDE COMPOSITES

LaRC(TM)-IAX (Langley Research Center - Improved Adhesive eXperimental Resin) aromatic polyimide is based on oxydiphthalic anhydride and 90: 10 ratio of 3,4'-oxydianiline and 1,4-phenylenediamine. To evaluate th e powder-form of this material as a matrix for high performance compos ites, three LaRC(TM)-IAX powders were prepared with three, four, and f ive percent stoichiometric imbalance via end-capping with phthalic anh ydride, affording theoretical number average molecular weights of 15,8 92, 11,858, and 9,438 g/mol, respectively. Thermal and rheological pro perties and the residual solvent content of the three powders were obt ained. Unidirectional IM7 powder-coated towpreg made from each of the three resins was frame-wrapped and consolidated into unidirectional la minates. With slight modification, the consolidation cycle developed p reviously for IM7/LaRC(TM)-IAX solution-coated composites was found to be equally applicable for IM7/LaRC(TM)-IAX powder-coated composites. Composite mechanical properties were obtained and processing and prope rty relationships were established.