Toughening and reinforcing wood flour/polypropylene composites with high molecular weight polyethylene under elongation flow

Abstract

Toughening modification often reduces the stiffness of wood–plastic composites (WPCs). In this study, wood flour/PP composites with high molecular weight polyethylene (HMWPE) were toughened and strengthened under elongation flow by using an Eccentric Rotor Extruder (ERE). Under elongation flow, the incorporation of HMWPE into wood flour/PP composites improved the tensile strength, flexural strength, flexural modulus, notched impact strength, and un-notched impact strength by 23.2%, 24.9%, 26.3%, 67.3%, and 67.7%, respectively, compared with wood flour/PP/HMWPE composites processed by using a torque rheometer. The strengthening and toughening mechanisms of the resulting composites were investigated. The former is related to the oriented crystals and wood flour, the higher polymer crystallinity and the improved interfacial adhesion between the polymer matrix and wood flour. The latter depends on the better HMWPE dispersion, the strengthened interface between PP and HMWPE and the better interfacial adhesion between wood flour and the matrix. These results provide exciting opportunities for further widespread functional applications.