Short-fibre hybrid polypropylene composites reinforced with PET and Rayon fibres - Effects of SSP and interphase tailoring

This research focused on manufacturing of light-weight hybrid polypropylene composites reinforced with short fibres from polyterephthalate and rayon-viscose yarns. The aim of hybridisation of reinforcements was to improve some aspects of mechanical performance of these composites and to reduce their cost. For the first reason also three methods of fibre-matrix interphase tailoring and solid state polycondensation of PET fibres were applied and investigated in terms of influence on their strength, moduli and impact behaviour of composites. Lower density of PET and rayon-viscose fibres in comparison to glass fibres had to a large degree compensated the specific properties of manufactured hybrids. The same level of drop-weight impact energy absorption was achieved for hybrids as for their PP-GF counterpart, while merely 25% lower specific flexural strength was obtained. The HDT was only ∼15 degrees lower. Therefore the developed composites may substitute a standard PP-GF in some particular lightweight applications. The results give also insight into properties and mechanical behaviour of applied fibres and how they can be altered during processing.