Investigation of the Effect of Filler Loading on Mechanical Properties of Sawdust-Filled Polyester Composites

The generation of large volumes of sawdust waste from timber processing industries in South West Nigeria presents both an environmental disposal challenge and an opportunity for value addition through composite material applications. This study investigates the effect of sawdust filler loading on the mechanical properties of sawdust-filled unsaturated polyester composites fabricated from timber waste collected at sawmills in Osogbo, Osun State. Sawdust particles were sieved to a uniform size range of 250 to 500 micrometres and incorporated into the polyester matrix at weight fractions of 10, 20, 30, 40, and 50 percent. Composite specimens were fabricated by casting and cured at room temperature. Tensile strength, flexural strength, impact strength, and hardness were determined following standard ASTM test procedures. Results indicated that tensile strength decreased progressively with increasing filler content, while hardness increased up to the 30 percent filler level and subsequently declined due to particle agglomeration effects. Flexural strength showed a maximum at 20 percent filler loading of 68 MPa, above which values decreased. Impact strength was highest in the unfilled resin and reduced monotonically with increasing sawdust content. The study concludes that sawdust-filled composites at 20 to 30 percent filler loading offer acceptable mechanical performance for non-structural applications such as furniture panels, decorative tiles, and partition boards, providing a pathway for sustainable utilisation of timber waste. Keywords: sawdust-filled composite, polyester matrix, filler loading, mechanical properties, timber waste.