ABSTRACT
In this work, wood plastic composites made of HDPE and different types of wood sawdust generate at furniture industries are characterised. The equipment used was a 19 mm co-rotating twin-screw extruder, complementing previous studies where the composites were mixed using a single-screw extruder. Temperatures of 180oC were applied at the five heating zones, rotating at 150 rpm with a flux of 1 kg.h-1. Residues of MDF, of loblolly pine and of eucalypt wood were used, and were mixed into the HDPE with a coupling agent (anhydride maleic). Physical characterization of the composites was performed by differential scanning calorimetry (DSC) and by scanning electronic microscopy. In addition, the mechanical properties of tension, static bending and impact were analysed, according to ASTM D638, D790 and D256. All types of sawdust acted as a nucleate agent, since the composites showed a crystallinity index higher than pure HDPE. Also, it was observed that the type of sawdust influenced fibre’s dispersion in the polymeric matrix. The mechanical tests showed differences in the properties of the composites made of different types of sawdust. In general, inclusion of MDF sawdust resulted in composites with higher bending strength and impact work than those containing eucalypt and pine. Comparing results obtained using a single-screw extruder and values obtained in this study, it can be concluded that the properties of the wood are more effectively transferred to the composite using a double-screw extruder.
Keywords:
composites; HDPE; sawdust