THE INFLUENCE OF THERMAL HISTORY ON THE MECHANICAL-PROPERTIES OF POLY(ETHER ETHER KETONE) MATRIX COMPOSITE-MATERIALS

The purpose of this study is to provide insight into the microstructur al factors that affect the flexural fatigue performance of carbon-fibr e-reinforced poly(ether ether ketone) (PEEK) composites. Specifically, the effect of the degree of crystallinity on the mechanical propertie s is examined at two crystallinity levels of the as-received composite s (35%) and of quenched composites (10%). Higher static flexural stren gth and modulus as well as longer fatigue life are observed for the hi gher crystallinity level. By varying the loading angle with respect to the fibre direction it is shown that the crystallinity effect is not matrix dependent alone. Rather, a strong effect is evident in the fibr e direction, which is attributed to the influence of the trans-crystal line layer formed on the fibre surface in the high-crystallinity mater ial. As a result, the longitudinal fatigue life at 1.7 GPa of the 35% crystallinity material is three orders of magnitude higher than that o f the 10% crystallinity composite.