Remarkable Cassava Rhizome Powders as Bio‐Reinforcing Filler in Wood Thermoset Composites

ABSTRACT The use of agricultural waste provides significant environmental benefits. This study utilized cassava rhizomes, an agricultural byproduct from Chaiyaphum, Thailand, as a bio‐reinforcing filler in epoxy‐based wood composites. The effects of particle size and filler content (0%, 10%, 20%, and 30% by weight) on physical and mechanical properties were investigated. Composite samples were fabricated using silicone molds with three particle sizes of cassava rhizome powder. Results showed that powder size and content significantly influenced composite performance. At 30 wt% of the smallest particles, Young's modulus reached 1.67 GPa (an increase of 138.6%), hardness was 76.2 Shore D (an increase of 39.3%), flexural strength was 43.5 MPa (an increase of 18.8%), and flexural modulus was 2.38 GPa (an increase of 55.6%) compared to pristine epoxy, due to enhanced stiffness. Water absorption increased to 4.04% (a factor of 7.5), and bulk density rose to 1.18 g/cm 3 (an increase of 3.5%) owing to the hydrophilic nature and density of cassava rhizomes. These findings demonstrate the potential of cassava rhizome powders as sustainable bio‐fillers for developing eco‐friendly wood‐epoxy composites with applications in furniture, ceilings, flooring, and wall panels.