The Effects of Alkaline Treatment on Physical and Mechanical Properties of Oil Palm Trunk/Polypropylene Blends Composite

Abstract

Wood-plastic composites (WPCs) are composites that incorporate plants composed up of wood and non-wood fibres blended with thermosets or thermoplastic polymers to form a composite. Oil palm trunk (OPT) is one of the wastes produced from the oil palm industry known as oil palm biomass (OPB). The OPT was utilized to turn oil palm biomass into a value-added product. In this research, oil palm trunk/polypropylene (OPT/PP) blends composite was produced by extrusion and injection molding techniques. Alkaline treatment was applied to the fibers to improve the interfacial adhesion of fibers. After alkaline treatment, treated OPT (T-OPT) and untreated (UT-OPT) together with PP were blended at 200°C with the speed of 85 rpm in the extruder to form a pellet. Pellets were then injected in injection molding at 200°C to form sample size for mechanical testing; tensile and impact testing. The physical testing conducted was Melt Flow Index (MFI), water absorption test and Thermogravimetric Analysis (TGA). The results show that the mechanical properties of OPT/PP composite were improved by alkaline treatment. In the water absorption test, T-OPT composite demonstrated lower water absorption than that of UT-OPT composite. This indicated that the reduction of water absorption in T-OPT composite is due to alkaline treatment that degraded the lignin and cellulose structure subsequently reducing the OH groups in fibers to absorb water. For TGA, T-OPT composite had slightly higher thermal stability as compared to UT-OPT composite.