Effect of inorganic pigments on the properties of coextruded polypropylene-based composites

In this article, the effect of the incorporation of three inorganic pigments on the properties of coextruded polypropylene-based composites was studied. Three different pigments were incorporated in the shell layer of the composites: iron oxide, titanium dioxide (TiO 2 ) and zinc oxide (ZnO). The tensile properties and Charpy impact strength of the composites were tested. A water immersion test was conducted. The morphology of the fractured surfaces of composites was characterised by scanning electron microscopy. The durability of the composites was assessed by testing colour characteristics and tensile strength after 500 hours of accelerated weathering. The results revealed that the TiO 2 -containing composite had the highest tensile modulus and Charpy impact strength, while the ZnO-containing composite had the lowest tensile strength and Charpy impact strength. Iron oxide was found to have no effect on either the physical or mechanical properties of the composite. The porosity of composites influences their water absorption and thickness swelling. The TiO 2 -containing composite exhibited better colour stability.