Mechanical Properties of Wood Flour Polypropylene Composites: Effect of Cycled Temperature Change

Abstract

ABSTRACT ：The effect of cycled temperature change on the mechanical properties of wood flour(50 wt.% and 70 wt.%)polypropylene WPC(Wood Plastic Composites) was investigated in this study. Flexural modulus and flexural strength of the WPC showed a decrease due to the degradation of interfacial adhesion between polymer matrix and wood flour bythe freeze-thaw test regardless of the cycled number. At the higher loading level of wood flour, the reduction of the flexuralmodulus was remarkable. After the cycled heat-freeze test, it was found that the flexural modulus and flexural strengthof the WPC were lower at the high temperature (60℃) and higher at the low temperature (-20℃). At the low temperature(-20 ℃) which is below glass transition temperature of polypropylene (-10℃), WPC is in a glassy state which brings about the high stiffness and strength. At the high temperature (60℃), the flexural modulus and flexural strength of the WPC with 50 wt.% wood flour were lower because of the increase of polymer ductility.