Research on Rheological Properties of Wood Flour/Polypropylene Composites

The influences of coupling agent, wood flour content and lubricants on the processing flow and dynamic rheological properties of wood flour/polypropylene (WF/PP) composites were investigated through torque and rotational rheometer. Results showed that the addition of maleic anhydride grafted polypropylene (MAPP) improved the interfacial adhesion of wood flour and polypropylene, which increased the equilibrium torque and complex viscosity of WF/PP melts. With the increasing of wood flour content, the equilibrium torque, shear heat, storage modulus, loss modulus, complex viscosity and characteristic relaxation time were increased and the linear viscoelastic region (LVR) was decreased. The addition of stearic acid significantly reduced the equilibrium torque and shear heating of the composite, and the melt viscosity resulted from high wood flour loading was also reduced dramatically. This indicated that stearic acid lubricant effectively improved the processing flow properties of WF/PP melts in the presence of higher wood flour loading.