New bismaleimide matrix resins for graphite fiber composites

Two new bismaleimide resins based on the N,N'-m-phenylene-bis(m-amino-benzamide) structure have been synthesized and characterized. The mixtures of the two resins gave better handling, processing, mechanical, and thermal properties in graphite composites than did the individual resins. The mechanical strength of the cured graphite composites prepared from the 1:1 copolymer of the two bismaleimide resins was excellent at both ambient and elevated temperatures. The physical and mechanical properties of the composites from the new bismaleimide matrix resin systems are compared with conventional composites based on epoxy and other bismaleimide systems. The copolymer system provides another method for improving bismaleimide resins.