Rheological and Mechanical Characterization of Polypropylene-Based Wood Plastic Composites

The aim of this article is to investigate the influence of filler content and temperature on the rheological, mechanical, and thermal properties of wood flour polypropylene composites (WPCs). Testing WPCs at high temperatures and percentages of filler is extremely challenging because of reduced linear viscoelastic region, high viscosity, and degradation. In this work, a complete characterization of WPCs with different filler percentages (0-70 wt%) has been made. Rheological tests are performed at 170 degrees C for the WPCs and in the 170-200 degrees C range for neat polypropylene. A single master curve is obtained using two shift factors that can be described by a modified Eilers model and a Williams-Landel-Ferry equation. This master curve, fitted with a Carreau-Yasuda model, can be very useful for predicting the viscosity of WPCs at temperatures that are typically used during processing and for any percentage of filler. (C) 2015 Society of Plastics Engineers