Processing and properties of new high-temperature, lightweight composites based on foam polyimide binder

We report a method for making novel, lightweight (p = 0.3-1.1 kg/dm(3)) pol ymer composites based on high-temperature foam polyimide binder, carbon fib ers, and organic fibers. The density and mechanical properties of the foam composite can be varied over a relatively wide range, depending on the volu me contents of the fiber and air pores. The resin's high glass transition t emperature of 260 degrees C, coupled with the high thermal stability of car bon or polyimide fibers, contributes to its excellent retention of mechanic al properties at elevated temperatures. The temperature at the beginning of weight loss is not lower than 570 degrees C and depends on the kind of fib er felt. The combination of excellent thermal and specific mechanical prope rties of foam composites together with exceptional thermal stability and pr ocessability on conventional molding equipment can provide unusual performa nce for the new design of advanced materials and structures.