Biodegradable composites from waste wood and poly(vinyl alcohol)

An environmentally friendly wood-based product composed of waste wood and poly(vinyl alcohol) [PVA] modified by phthalic anhydride (PA), which possesses mechanical properties and weight loss liable to be controlled by reactants ratio, was produced. Sugi (Criptomeria japonica) flour was added to the PA/PVA reaction medium, and hot-pressed under 50 MPa at 180 °C. Varying the PA/PVA ratio yielded composites with flexural modulus of elasticity (MOE) values of ∼13 GPa and modulus of rupture (MOR) of ∼90 MPa. Degradation by microorganisms was performed by the soil burial test (a method adapted from the IPT, edition No. 1157 D5). The changes in the composites' structures throughout the biodegradation process were studied by infrared spectroscopy (IR) and scanning electron microscopy (SEM), and the decrease in mechanical properties monitored. A correlation was established between the structure, mechanical properties and weight loss of waste wood-PVA composites.