THE EFFECT OF BROMINE SUBSTITUTION ON THE FLAMMABILITY OF POLYIMIDES UNDER IR LASER IRRADIATION

New bromine-containing polyimides based on 1,3-diamino-5-bromobenzene and dianhydrides of tetracarboxylic acids with different bridge groups were prepared. It is shown that use of laser radiation for ignition o f these polymers and their bromine-free analogues makes possible to ca lculate the surface temperature of the polymer in the instant of flash . The halogen is an inhibitor of combustion of polyimides for the inte nsity of irradiation less than 100 - 140 Wt/cm(2). Upon further increa se in the radiation flux, the inhibiting effect decreases. It is found that coking value, oxygen index, and flash delay time linearly increa se with increasing rigidity of polyimide.