Abstract: The properties of two types of short carbon fibre (CF) reinforced thermoplastic resin composites (CF PPS and CF / PES C). such as tensile strength σy. Young's modulus E, and fracture toughness KIC, have been measured for varying volume fraction Vf of CF. It shows that moduli increase linearly as increasing of Vf with a Krenchel's efficiency factor 0.05, whereas σy and KIC rise at first and then peak at Vf of order 0.25. The experiments results have been explained as viewed from characteristics of fibre / matrix adhesion according to the analyses of load-deflection curves and fractography. By using crack pinning model, the effective crack tensions T were calculated for both composites and they are 26kJ / m (for CF PPS) and 2.1kJ / m (for CF/ PES-C) respectively. The localized plastic deformation near fibre / matrix interface provides the major contribution to crack tension.

Key words: rirbon tibre, thermoplastic resin, umposte, crack pinning, fracture toughness