Isothermal crystallization and melting behavior of short carbon fiber reinforced poly(ether ether ketone) composites

Films of short carbon fiber reinforced poly(ether ether ketone) (PEEK) comp osite were formed by compression molding pellets for 10 min at 380 degrees C under air. A heating stage was used to prepare isothermally treated PEEK composites before DSC scan. The dependence of degree of crystallinity on th e heating rate (10-80 degrees C/min) was investigated for specimens crystal lized at different temperatures. The results indicated that 50 degrees C/mi n was an optimum heating rate to suppress the reorganization and to avoid t he superheating of high crystallinity specimens with the sample weight of 1 0 mg. The upper peak temperature of double-melting peaks continued to incre ase with crystallization temperature. This peak temperature was related to the transition from regime II to III. The phenomenon of lower crystallinity and higher melting temperature supports the interpretation that the upper melting peak corresponded to crystals growing during the earlier stage of i sothermal crystallization.