Effects of teak wood and polycarbonate additives on the tensile, flexural and impact performances of HDPE-based wood–plastic composites

This study investigated the effects of teak wood sawdust and polycarbonate (PC) additions on the mechanical properties, including tensile strength, elongation at break, flexural strength, and impact resistance of wood–plastic composites based on high-density polyethylene (HDPE) and compatibilised with 4 wt. % PE-grafted-maleic anhydride. The composites were fabricated via injection moulding, and an experimental design was conducted using the Taguchi L9 orthogonal array method. Three factors were studied: PC content (0, 7.5 and 15 wt. %), teak wood content (20, 30 and 40 wt. %), and sawdust particle size (1.5–1, 1–0.85 and 0.85–0.6 mm). Multi-criteria decision-making (MCDM) analysis was employed to identify the optimal composite. The results indicated that the incorporation of teak wood significantly improved the flexural strength, with an increase of up to 94.6% compared to pure HDPE composites. However, the addition of polycarbonate generally had an adverse or negligible effect on tensile strength, elongation at break and impact resistance. Among the nine samples, Sample 1-containing 0 wt. % PC, 20 wt. % teak wood and 1.5–1 mm particle size-achieved the best overall mechanical performance, with a tensile strength of 31.83 MPa, a flexural strength of 45 MPa, an elongation at break of 18.3% and an impact resistance of 26.88 kJ/m 2 . Overall, it was concluded that while teak wood is an effective reinforcement to enhance the flexural behaviour of HDPE-based WPCs, the addition of PC does not provide sufficient benefits and is economically unjustifiable under the studied conditions.