Fracture characteristics of short glass fibre/maleated styrene-ethylene-butylene-styrene/polypropylene hybrid composite

Maleated styrene-ethylene-butylene-styrene triblock copolymer (SEBS-g-MA)/polypropylene 20/80 and SEBS/PP 20/80 blends reinforced with 30 wt% short glass fibres (SGF) were prepared by extrusion and subsequent injection moulding. The impact strength and fracture toughness of the hybrid composites were measured with the instrumented Charpy drop-weight impact test and essential work of fracture (EWF) method. Drop-weight impact measurements showed that the SGF/ SEBS/PP composite exhibits higher impact strength than the SGF/SEBS-g-MA/PP hybrid at low impact speeds. Fibre pull-out was responsible for the improved impact energy of the SGF/SEBS/PP composite subject to low impact velocity. At high impact speeds, the impact energy of the SGF/SEBS-g-MA/PP hybrid was slightly higher than that of the SGF/SEBS/PP composite. This was attributed to localized plastic deformation occuring in the fibre-matrix interfacial region. However, the EWF method revealed that the toughness of the SGF/SEBS-g-MA/PP hybrid was lower than that of the SGF/ SEBS/PP composite. The effect of maleic anhydride (MA) functional groups grafted to SEBS on the fracture behaviour of the SGF/SEBS/PP hybrid composite is discussed. © 2002 Society of Chemical Industry.