Investigation of the physical and mechanical properties of Wood plastic composites based on high density polyethylene/ polypropylene/recycled poly (ethylene terephthalate)

Several advantages such as low cost, availability of renewable natural resources and high stiffness are main reasons to pay attention to wood plastic composites. In this work, the blends of high density polyethylene (HDPE), polypropylene (PP) and recycled poly (ethylene terephthalate) (rPET) with maleated polyethylene (MAPE) and maleated polypropylene (MAPP) as the compatibilizer were used as the matrix of the wood-plastic composites (WPCs). WPCs has been prepared through an extrusion technology in two-step. In the first step, the bland of matrix (PP/HDPE/rPET) has been prepared, and in second step, the wood flour was added to polymer matrix to produce wood plastic granules. Wood plastic granules were converted to test samples through injection molding technology. The effects of rPET, wood flour and compatibilizer content on the mechanical properties (tensile strength, flexural strength, tensile modulus, elongation at break point and impact energy), density and water absorption resistance of WPCs were investigated. The results showed that the tensile modulus, density and water absorption of WPCs increased with rPET and wood flour, and impact strength and elongation at break point decreased. Tensile and flexural strength increased with rPET, whiles the strength significantly did not change with wood flour. Mechanical properties (elongation, impact energy, tensile modulus and flexural and tensile strength) and water absorption resistant improved with compatibilizer content. SEM images showed that rPET converted to micro fiber in matrix after second step of the extrusion.