Impact properties of glass fibre/impact modifier/polypropylene hybrid composites

The impact properties of glass-fibre/impact-modifier/polypropylene (GF/IM/P P) hybrid composites were characterized using a number of impact test metho ds. For the IM/PP blends, the impact fracture toughness can be measured usi ng linear elastic fracture mechanics (LEFM) approach. For the GF/IM/PP hybr ids, due to their non-compliance with LEFM, the essential work of fracture approach was employed. The impact properties of the IM/PP blends increased with IM concentration, while that of the GF/IM/PP hybrids did not change ve ry much with IM content. It was concluded that cavitation of the PP matrix around the IM particles was the major toughening mechanism in the IM/PP ble nds. However, in the GF/IM/PP hybrids, the toughening effect due to cavitat ion was suppressed due to the introduction of short glass fibres (approxima te to 15 vol%). It is believed that the local stress in the matrix was reli eved by fibre/matrix debonding of the relatively weak fibre/matrix interfac e. Thus, the presence of the IM particles was rendered insignificant in the GF/IM/PP hybrids. (C) 2000 Kluwer Academic Publishers.