Mechanical performance and surface characteristics of polyethylene terephthalate and high-density polyethylene blended with tropical hardwood sawdust

This study evaluates the physical, mechanical, and aesthetic properties of wood-plastic composites (WPCs) produced from blends of Gmelina arborea and Khaya senegalensis sawdust with recycled polyethylene terephthalate (PET) and high-density polyethylene (HDPE). Sawdust and plastic samples were collected and prepared for the experiment. Three formulations were tested: two PET and HDPE-only blends (60:40 ratio) and one composite with 20% PET, 20% HDPE, 30% G. arborea, and 30% K. senegalensis. Composite Boards containing sawdust exhibited superior performance across all metrics: highest density (0.61 ± 0.22 g/cm³), lowest shattered index (6.68%), highest Shattered Resistance (93.32%), improved Modulus of Elasticity (8.26 ± 4.14 N/mm²), enhanced Modulus of Rupture (8.57 ± 6.19 N/mm²), and competitive compressive strength (150.82 ± 40.07 N/mm²). Incorporating sawdust significantly enhanced mechanical and physicalproperties (p < 0.05), while PET/HDPE ratio variations alone showed minimal impact. Aesthetically, the sawdust composite displayed a uniform dark brown color and smoother surface compared to the rough, monochromatic PET/HDPE Boards. This work contributes to circular economic goals by valorizing wood and plastic waste while reducing reliance on virgin materials. Integrating sawdust from G. arborea and K. senegalensis with recycled PET and HDPE enhances the performance and appearance of wood-plastic composites, making this approach a sustainable and effective option for material reuse and circular economy initiatives.