Alternative polymeric matrices for wood-plastic composites: Effects on mechanical properties and resistance to natural weathering

Abstract

The influences of plastic matrix on mechanical properties (flexural and tensile properties) of wood-plastic composites (WPCs) were investigated. WPCs were prepared with five types of plastic as the matrix phase, namely high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), and polystyrene (PS). Rubberwood flour was used as reinforcing filler. Additionally, maleic anhydride, UV-stabilizer, and paraffin wax were used as coupling agent, ultraviolet stabilizer and lubricant, respectively. The WPCs were produced in two stages: mixing in an internal mixer, and compression molding. WPCs from PS and PP exhibited higher mechanical properties whereas LDPE, HDPE, and PVC gave lower values. In particular LDPE gave consistently the poorest mechanical properties to WPCs. Moreover, the WPCs with PS and PP had the smallest losses of mechanical properties from natural weathering, while LDPE would again be the poorest choice in this respect. These results indicate that WPCs from PP and PS are the best alternatives for applications requiring resistance to natural weathering (exposure to ultraviolet and humidity) or with high mechanical loading (stresses).