Paper number 185

CRYSTALLINITY AND INTERPHASE PROPERTIES OF CARBON FIBRE/PEEK MATRIX COMPOSITES

Shang-Lin Gao and Jang-Kyo Kim

Department of Mechanical Engineering
Hong Kong University of Science & Technology
Clear Water Bay, Hong Kong

Summary

The influence of thermal history on interfacial properties of carbon fibre reinforced poly(etheretherketone) (PEEK) matrix composites was studied. The fibre fragmentation and pull-out tests were used to measure the interfacial shear strength (IFSS). The correlations between IFSS, degree of crystallinity, morphology, and failure mechanisms were established. It is shown that the amorphous PEEK-rich interphase introduced in fast-cooled specimens or those crystallised at a low isothermal temperature resulted in ductile interface failures along with a low IFSS, whereas the transcrystalline interphase obtained for slow-cooled specimens or those crystallised at a high isothermal temperature gave rise to a high IFSS with brittle interface debonding. The dependence of the interlaminar shear strength (ILSS) on thermal history is explained by the transition of failure mechanisms, which are in turn controlled by the interphase morphology, ductility and IFSS.

Keywords

Carbon fibre/PEEK composite, cooling rate, isothermal crystallisation, degree of crystallinity, interfacial shear strength, failure mechanism.