Effects of wood flour content and heat treatment on the dynamic mechanical and impact properties of LDPE/red balau (Shorea Dipterocarpaceae) composites

Red Balau saw dust was heat-treated at 180 °C and 200 °C for one hour and compounded with low-density polyethylene, LDPE, at 9, 20 and 37 wt%. The compounded materials were injection moulded into test specimens. Charpy impact assessment of the notched samples of the composites revealed that the peak load, P, and the critical stress intensity factor, K_c, increased with wood content and treatment temperature. While the energy to failure, W , and the critical strain energy release rate, G_c, decreased with wood content, the values were highest in composites made from wood flour treated at 180 °C and reduced in 200 °C treated wood composites. This behaviour revealed that heat treatment of wood flour at the 200 °C resulted in poorer impact properties of the composites. Dynamic mechanical analysis showed an increase in storage and loss modulus of composites made from untreated wood flour relative to the heat-treated ones. Tan delta values were also found to reduce in the heat-treated wood composites as a result of decreased damping. Heat treatment of wood flour at appropriate temperature enhanced both the mechanical and dynamic mechanical properties of the composites.