Macro- and micromechanical response of glass fibre-reinforced polypropylene to pigmental impurities
Ryszard Sikorski
Quarterly No. 1-2, 2021 pages 22-28
DOI:
keywords: polypropylene, recyclate, short glass fibre, titanium dioxide, carbon black, zinc sulphide, zinc oxide
abstract The present study investigates the influence of pigmental impurities on glass fibre-reinforced polypropylene using model compounds to simulate the behaviour of recyclate-based compositions. Most industrial-quality (containing recyclate) PP com-pounds are black coloured (using carbon black pigment), with an almost unavoidable presence of inorganic white pigment (e.g. titanium dioxide) impurities. There are widespread beliefs in the compounding industry that such impurities have a det-rimental effect on the mechanical properties of glass fibre-reinforced compounds, but up to now no systematic study of this problem from the industrial point of view has been reported. For this purpose, a range of compounds was prepared on a twin-screw compounding line and the properties were evaluated, with special focus on the mechanical properties. The results con-firmed the strong influence of some white pigments, particularly titanium dioxide, and rejected the thesis of the detrimental action of carbon black.