'Department of Polymer Engineering, Scientific Society of Mechanical Engineering'
Doi
Abstract
In this work, all-polypropylene composites (all-PP composites) were manufactured by injection moulding. Prior
to injection moulding, pre-impregnated pellets were prepared by a three-step process (filament winding, compression
moulding and pelletizing). A highly oriented polypropylene multifilament was used as the reinforcement material, and a
random polypropylene copolymer (with ethylene) was used as the matrix material. Plaque specimens were injection
moulded from the pellets with either a film gate or a fan gate. The compression moulded sheets and injection moulding
plaques were characterised by shrinkage tests, static tensile tests, dynamic mechanical analysis and falling weight impact
tests; the fibre distribution and fibre/matrix adhesion were analysed with light microscopy and scanning electron
microscopy. The results showed that with increasing fibre content, both the yield stress and the perforation energy significantly
increased. Of the two types of gates used, the fan gate caused the mechanical properties of the plaque specimens to
become more homogeneous (i.e., the differences in behaviour parallel and perpendicular to the flow direction became negligible)