Fracture behaviour of discontinuous long glass fibre reinforced injection moulded polypropylene

The in- and out-of-plane fracture behaviour of injection-moulded discontinuous long glass fibre reinforced (DLGF) polypropylene composites (PP) as studied. The DLGF content (0-11 wt%) and thickness of the molded plaques were varied. The in-plane fracture toughness, as assessed by the essential work of fracture (EWF) method, showed a clear anisotropy, This was explained by the effects of the DLGF orientation and distribution, confirmed by fractography. The out-of-plane instrumented falling weight impact (IFWI) toughness of the 4 mm thick plaques was higher than that of the 2 mm thick ones. This was attributed to the onset of shear fracture, supported by the DLGF alignment across the plaque thickness in the thicker plaques.