Mode 1 Interlaminar Fracture Behaviour of Continuous Glass Fibre/Polypropylene Composites Based on Commingled Yarn

摘要

The mode 1 interlaminar fracture behaviour of commingled glass fibre/polypropylene(GF/PP)composites moulded at different cooling rates was investigated.The composites were prepared from unidirectional,woven fabric and mat plies,respectively,and tested using double cantilever beam specimens.The results showed that mat composites possessed the highest interlaminar fracture toughness,whereas woven fabric laminates were the most sensitive to delamination at a fixed cooling condition,as a result of different crack propagation mechanisms.For woven fabric composites,a small amount of debonding of transversely oriented fibres occurring periodically on the free edge is thought to have been responsible for the lowest interlaminar fracture toughness.As expected,extensive fibre bridging and tortuous crack growth path effectively improved delamination resistance of unidirectional laminates.The highest interlaminar fracture toughness for mat laminates was attributed to pronounced debonding of off-axis fibres or yarns combined with pull-out of through-thickness fibres during crack propagation.Moreover,it could be deduced that using different cooling rates would impose various levels of delamination resistance in GF/PP composites because of the considerable effect on the microstructure of the PP matrix and on fibre-matrix interactions.Micrographs of the fracture surfaces of the specimens proved the important role of the amorphous PP phase at the fibre-matrix interface.