| Material properties and extrusion behaviour of wood-HDPE blends were investigated in this research work. Material properties studied included rheological properties, physical properties, and composite morphology. The rheological properties were conducted using both capillary and rotational rheometers; the physical properties were studied by both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA); finally, the composite morphology was investigated by scanning electron microcopy (SEM).; Extrusion experiments were conducted to investigate the extrusion behaviour of the wood-HDPE blends such as outputs, melting profiles and pressure profiles. Three screw geometries were used, screws A, B and C. Screws A and B had the same solid conveying geometry, but a different compression ratio; screws A and C had the same metering depth, but a different compression ratio. Screws B and C had the same compression ratio, but different depths throughout the screw length. There are 10 pressure transducers placed along the barrel to measure the pressure profiles. The melting profiles were investigated by both screw extraction experiments and pressure profiles over time at a certain location along the screw.; A commercially available screw software program was used to compare the experimental results to simulation results based on current theory. While good agreements were found for the virgin HDPE resin, the performance of the wood-HDPE blends was poorly predicted. This was expected due to the presence of partially filled channels for these blends. The solid conveying model based on Chung's viscosity model was modified. Better predictions were seen in the solid conveying section. |
