The mechanical and thermal properties of wood plastic composites based on heat‑treated composite granules and HDPE

To improve the mechanical and thermal properties of wood plastic composites for building and structural applications, pretreatment was applied to the composite granules. A melt compounding process was employed in the manufacturing of the composite granules. The extruded composite granules were dried at 95–135 °C for 24 h. Composites were also prepared from composite granules at room temperature which served as the control. The optimum pretreatment temperature was found at 105 °C, where the mechanical properties were optimized. The SEM results showed that the composites made from heat-treated granules at 105 °C have better interfacial bonding due to adequate wetting compared to their untreated counterparts. FTIR spectroscopy revealed no significant changes in the intensity and shape of the peaks between the treated and untreated granules, which implies that the heat treatment has a negligible influence on the functional groups present. Overall, the results demonstrate that the pretreatment of composite granules is a viable strategy for obtaining biocomposites with improved mechanical and thermal performance.