Effect of Heat Treatment of Wood Flour on the Water Absorption and Mechanical Properties of Red Balau Saw Dust /LDPE Composites

Abstract

Due to the hygroscopic nature of wood, its use in wood thermoplastic composites (WTC) in outdoor industrial and domestic applications is limited. Wood is usually modified to reduce this tendency. Red balau saw dust was modified by heat treatment at 180°C and 200°C for 1 hour, compounded with LDPE at 20% and 37% by weight and molded into test specimens by injection molding. Samples were immersed in distilled water at room temperature for four months. Pure LDPE did not absorb water as no weight gain was recorded throughout the experimental period. Composites containing heat treated wood flour show remarkable water resistance than those made from untreated ones. Reduced water absorption of treated wood composites relative to untreated ones indicates a degree of modification by heat treatment. Tensile and flexural tests results revealed that the untreated wood composites have poorer mechanical properties with water immersion as a result of degradation due to moisture. The mechanical properties of composites made from heat treated wood flour were not adversely affected with water absorption. Therefore, heat treatment is capable of reducing the proneness to water absorption in WTC, alleviate the detrimental effects on mechanical properties and provide a good way of improving the WTC properties in applications that poses moisture related challenges.