Phosphorus-Containing Imide Resins. I

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Abstract
Recently we reported the general features of bisimide resins based on bis(m-aminophenyl)methylphosphine oxide. Graphite fabric composites fabricated from one of these resins did not burn in pure oxygen even at 300°C. However, curing of these resins was done above 270°C. It is desirable to have organic matrix resins with lower curing temperatures. We now report the synthesis of several bislmides and triimide resins based on tris(m-aminophenyl)phosphine oxide. These monomers were prepared according to the procedure of Searle or Martin et al. by reacting triamine with appropriate amounts of maleic anhydride, citraconic anhydride, dichloromaleic anhydride, and benzophenone tetracarboxylic dianhydride. Cross-linked imide resins insoluble in DMF were obtained by thermal polymerizations at 180°C with some of these monomers. Anaerobic char yields at 800°C in the range of 60–70% were obtained. A four-ply graphite cloth laminate prepared from one of these resins at 180°C, and after postcuring at 220°C for 4 h, had a limiting oxygen index above 100. The glass transition temperature of this laminate (as evaluated by DMA) was 385°C.