Polypropylene hybrid composites reinforced with long glass fibres and particulate filler

Structure and fracture behaviour of long glass fibre (LGF) reinforced polypropylene (LGF PP) composites including calcium carbonate (CaCO3) as a filler were studied. Fibre orientation, fibre length distribution and mechanical properties of LGF PP/CaCO3 hybrid composites, as well as the crystallinity changes of polypropylene upon filler addition are reported. Furthermore, an acoustic emission (AE) analysis was applied to the fracture mechanical test, in order to get information about the fracture modes during the loading. It was found out that the filler addition had little effect on the fibre orientation and crystallisation behaviour of LGF PP, but the average fibre length decreased. AE analysis showed that the addition of filler caused early stage debonding of the LGFs, when the samples were subjected to low speed tensile loading (1 mm/min). These observations may explain the changes of the mechanical properties of LGF PP upon filler addition.