Effect of processing parameters on the properties of polypropylene–sawdust composites

Considering the boom in the market for wood plastic composite (WPC) products due to their relatively high specific strength properties, low maintenance costs, and wide range of applications, many authors have studied the performance of these composites prepared by reactive extrusion with different compatibilizers and peroxide types. This paper presents the density, chemical composition, and morphology of sawdust and the preparation and characterization of WPC with polypropylene by compression molding using different amounts of sawdust with and without coating with compatibilizer. Good-quality WPCs were obtained, as evident from almost identical experimental and theoretical density values of these composites. The WPCs prepared without compatibilizer coating exhibited low tensile properties. Irrespective of coating by different compatibilizers, the maximum tensile strength of all the WPCs decreased with increasing amount of sawdust. The WPCs prepared with uncoated sawdust fibers absorbed much more water than those prepared with compatibilizer-coated fibers, the latter showing increasing water intake with increasing amount of sawdust. These results are discussed in terms of melt-flow index, density differences, and adhesion between the sawdust and polypropylene.