Characterization and degradation of some phosphorus-containing polyimides

Phosphorus-containing polyimides and polysiloxaneimides were prepared via p hosphorylation of organosoluble polyimide. This was achieved by esterificat ion of their hydroxyl groups with diphenylphosphoryl chloride. The phosphor ylation was confirmed by infrared (IR), P-31 nuclear magnetic resonance (NM R) and phosphorus content analysis. The thermal decomposition behavior of t he phosphorus-containing polyimide was investigated by thermogravimetry and compared with unmodified polyimide. The polyimide with higher phosphorus c ontent displayed lower onset decomposition temperature and char yield. The apparent activation energies (E-a) were obtained following the methods of v an Krevelen, Horowitz-Metzger, Coats-Redfern, and MacCallum-Tanner. It was shown that E-a for thermal degradation of imide segments decreased with inc rease in phosphorus content. (C) 1998 Elsevier Science Ltd. All rights rese rved.