Abstract: The thermoplastic polyimidc(TPI)/carbon fiber(CF)composites were prepared using a twin-screw extruder. The effect of molding methods(injection and compression molding) on the propertics o f the composites was investigated.The results indicate, compared with the compression molding method，the injected composite possessed better mechanical properties. The injection molded specimen showed lower coefficient of linear expansion in machine direction. However, the injected specimen had higher friction coefficient and wear rate. Furthermore, making the use of the stress-strain curves and the scan electronic microscope photos of fracture surfaces, the working mechanism was analyzed.

Key words: thermoplastic polyimidc, carbon fiber, reinforcement, molding process, mechanical property