HIGH-TEMPERATURE THERMOSET POLYIMIDES CONTAINING DISUBSTITUTED ACETYLENE END-GROUPS

High-temperature thermoset polyimide resins were prepared using p-phen ylenediamine and a 1:3 mixture of 3,3-hexafluoro-2,2-bis(3,4-dicarboxy phenyl)propane dianhydride (6FDA) and 3,3',4,4'-tetra-carboxybiphenyl dianhydride (BPDA) for the imide backbone, and diarylacetylene derivat ives as reactive capping agents. The thermo-oxidative stability at 370 -degrees-C of the cured resins was evaluated in comparison with contro l samples based on several known reactive capping agents. The polyimid e resin end-capped with 4-(phenylethynyl)phthalic anhydride exhibited the best thermo-oxidative stability.