Mechanical properties of wood flour-filled polypropylene composites

Abstract

The effects of wood flour (WF) content and coupling agents on mechanical properties of compression moulded polypropylene composites containing 10-50% by weight of WF were investigated. WF was obtained from sawdust. The addition of WF in polypropylene increased the stiffness and hardness of the composite while the tensile strength, elongation at rupture and impact resistance decreased. To improve the adhesion between WF and polypropylene, WF was treated with silane coupling agents or Epolene wax before compounding. Tensile strength, tensile modulus and hardness of polypropylene-Epolene E-43P treated WF composites were marginally better than those of polypropylene-silane treated WF composites. Approximately 2 percent of Epolene E-43P in the composite was sufficient to provide most of the useful properties provided by that material in terms of tensile strength, modulus and hardness, with only a small sacrifice in impact behavior. Both the additive and the high processing temperature led to some wood degradation and to a Jess polar WF surface. Overall, these findings indicate that Epolene E-43P exerts some degrees of the coupling agent action which results in improvements in mechanical properties that are of practical value. The higher cost of Epolene E-43P can be compensated by the ratio of WF/polypropylene.