Oxidative aging of cured polymer from phyenylethynyl terminated imide oligomers

Cured phenylethynyl-terminated imide oligomers are being evaluated for use as structural resins in a High Speed Civil Transport. Oligomers with two di fferent backbone compositions and several different initial molecular weigh ts were cured in air and in nitrogen and the cured polymers were subjected to accelerated aging in ail: Initial stages of weight loss of powdered resi ns Jit Arrhenius expressions with activation energies of 143 to 182 kJ/mol. The room-temperature toughnesses of 40 mu m-thick films decreased followin g aging at 300-360 degrees C. Arrhenius extrapolations of lifetimes (define d as times to 10% loss of fracture toughness) exceed 10(5) hours at 177 deg rees C.