Thermal and mechanical properties of PAN- and pitch-based carbon fiber reinforced PEEK composites

Thermal and mechanical properties of different short carbon fibers (CF) reinforced polyether-ether-ketone (PEEK) composites are investigated, where CF is made from polyacrylonitrile (PAN-CF) and pitch (Pitch-CF). The thermal properties of both composites are studied using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystallinity of PEEK increases with the content of PAN-CF, but it is independent of Pitch-CF content. At the isothermal condition, the crystallite rate of Pitch-CF/PEEK composite is faster than that of PAN-CF/PEEK composites. Dynamic tensile modulus of PAN-CF/PEEK increases with the CF content. An increase of glass transverse temperature with an increase in CF content is found in PAN-CF/PEEK, but not in Pitch-CF/PEEK. The fracture toughness of PAN-CF/PEEK composites increases with CF contents; whereas it remains the same value for Pitch-CF composite. The fracture surface of both composites is analysed using scanning electron microscopy.