Mode I interlaminar fracture toughness of commingled carbon fibre/PEEK composites

Carbon fibre/poly (ether-ether-ketone) (PEEK) composites were fabricated from plain weave cloth using the commingled yarn of carbon fibres with PEEK filaments. The undirectional specimen was made from the warp of commingled yarn and the weft of PEEK yarn, while the two-dimensional specimen was made from commingled yarns both of the warp and the weft. During the hot-pressing process, PEEK filaments melt to form the matrix of the composite. The interlaminar fracture toughness of the commingled composite was measured and compared with that of the prepreg composite. The critical strain energy release rates,/'G_Ics, obtained for the commingled composites were higher than the prepreg composite. In particular, the two-dimensional composite exhibited higherG_Ic than the unidirectional commingled composite. Factors increasing the fracture toughness of commingled composites have also been investigated by SEM observation of the fractured surface.