Physical and Mechanical Properties of Composite Boards Made from Rice Straw and Recycled Foam

Abstract

This research aimed to investigate the physical and mechanical properties of straw–foam composite boards produced using 5% and 7% adhesive contents combined with straw-to-foam ratios of 95:5, 90:10, and 85:5. The boards were manufactured by the hot-pressing method. Physical properties, including moisture content, density, and thickness swelling, as well as mechanical properties, including tensile strength perpendicular to surface, modulus of rupture (MOR), and modulus of elasticity (MOE), were evaluated. The results showed that the boards had moisture contents in the range of 8.03–9.29%, densities of 0.71–0.84 g/cm³, and thickness swelling values of 2.63–6.00%, all of which complied with the Thai Industrial Standard for flat-pressed particleboard (TIS 876-2565). In terms of mechanical properties, all boards exhibited MOR values higher than the standard requirement. However, the tensile strength perpendicular to surface of all samples was lower than the standard, and only the boards produced with 5% adhesive at straw-to-foam ratios of 90:10 and 85:5 met the standard requirement for MOE. One-way ANOVA revealed that different adhesive contents and raw material ratios significantly affected moisture content, thickness swelling, tensile strength perpendicular to surface, and MOR at the 0.05 significance level, whereas no significant effect was observed on density and MOE. These results indicate that straw–foam composite boards have potential for development as commercial wood-based panel substitutes; however, improvements in internal bonding strength are still required.