EVALUATION OF SELCTED PHYSICAL AND MECHANICAL PROPERTIES OF WOOD PLASTIC COMPOSITE PRODUCED FROM THERMOPLSTIC WASTE AND WOOD SAWDUST

Abstract

ABSTRACT There are increasing environmental concerns on the need for sustainable materials for construction. Wood Plastic Composite (WPC), produced by the mixture of plastic wastes and lignocelluloses wastes offers a promising alternative to traditional wood products. This study evaluated selected physical and mechanical properties of WPC manufactured using recycled thermoplastic wastes of Polyethylene (PE) and Polypropylene (PP), with wood sawdust of Albizia zigia, Cleistopholis patens and Alstonia boonei in the following ratios of 30:70, 40:60 and 50:50 to achieve optimization for their applications. Separately prepared mixtures were compounded at 160oc in a twin-screw extruder. The resultant molten mixture, after extruding the die, was collected into a 22cmx4cmx4cm metal mould and compressed at 4.5 metric tons for one minute to form a composite block. The experiment was conducted in triplicates. Samples were sawn to dimensions recommended by the American Society for Testing and Materials. Physical and mechanical properties of (Density (D), Thickness Swelling (TS), Water Absorption (WA), Modulus of Elasticity (MOE), Modulus of Rupture (MOR), Impact Bending Strength (IBS) and Compressive Strength (CS)) were evaluated. The controls were wood samples of the species devoid of plastic. The results of selected physical properties showed that the density of A. zigia with PP at 30/70 had the highest mean value of 1.06±0.010 g/cm3, WA of A. boonei with PE at 50/50 had the least mean value of 0.67±0.010 % and TS of A.zigia with PP at 50/50 had the least mean value of 0.09±0.000 %. Analysis of variance on physical properties of wood species showed that there was a significant difference (p<0.05) in density and TS, while A. boonie showed significant difference in WA. Hard wood species increased density and reduced WA and TS in WPC production. The results of mechanical properties showed that MOE of A. zigia with PE at 50/50 had the highest mean value of 9684.21±1063.76 MPa, MOR of A. zigia with PE at 30/70 had the highest mean value of 63.33±3.41 MPa, CS of A. zigia with PE at 50/50 had the highest mean value of 45.44±1.79 MPa and IBS of A. zigia with PE at 30/70 had the highest mean value of 16.51±1.10 J/cm. Analysis of variance performed on mechanical properties of WPC showed significant difference (p<0.05) in MOE, MOR and CS except IBS. Sawdust of wood species with higher mechanical properties combined with PE polymer enhanced better mechanical performance of produced WPCs. Promoting WPC production according to requirement will enhance its application in the field of structural construction. Keywords: wood plastic composite,thermoplastic, sawdust, recycling