Interfacial shear strength and failure modes in sPP/CF and iPP/CF microcomposites by fragmentation

The aim of this study was to evaluate the transcrystalline effect on the in terfacial shear strength in a single carbon fibre (CF) reinforced syndiotac tic and isotactic polypropylene (sPP, iPP) composites by the fragmentation test. It was established that the sPP matrix exhibited a very good interfac ial bonding with high-tenacity (HT) CF. The interfacial adhesion was enhanc ed further by transcrystalline growth of sPP induced by a high-modulus (HM) CF. However, a poor interfacial adhesion existed between iPP and HMCF even in the presence of transcrystallinity. Matrix yielding and interfacial deb onding were the dominant failure mechanisms for the sPP/HMCF and iPP/HMCF m icrocomposites, respectively. The fraction and the location of the amorphou s phase along with a peculiar lamellar orientation in the transcrystalline layer were suggested to be responsible for improved interfacial shear stren gth. (C) 2000 Elsevier Science Ltd. All rights reserved.