Polypropylene hybrid composites with wood flour and needle-like minerals

Abstract

Polypropylene (PP) hybrid composites filled with wood flour and needle-like minerals, including SiO₂ whiskers, CaCO₃ whiskers and milled glass fibres, were prepared by melt blending and injection moulding. Maleic anhydride grafted PP was used as a compatibiliser. The effect of the needle-like minerals’ type and content on the crystallisation and melting behaviour, morphology, mechanical properties, moisture resistance and thermal stability of the hybrid composites were studied. The results showed that SiO₂ and CaCO₃ whiskers exhibited strong heterogeneous nucleation and promotion effect on PP crystallisation. Milled glass fibre was superior to enhance the tensile, flexural and impact properties of hybrid composites. Maleic anhydride grafted PP was selective for the interfacial modification of hybrid fillers and the best modification effect achieved in the composites hybridised with milled glass fibre. Comparatively speaking, the optimal proportions between the three kinds of needle-like minerals and the wood flour for the hybrid modification of PP all lie in 1·5∶48·5.