Wood-Fiber/High-Density-Polyethylene composites: Compounding process

The compounding process directly influenced the compounding quality of wood-polymer blends and finally affected the interfacial-bonding strength and flexural modulus of the resultant composites. With 50 wt % wood fiber, the optimum compounding parameters for the wood-fiber/high-density-polyethylene blends at 60 rpm were a temperature of 180degreesC and a mixing time of 10 min for the one-step process with a rotor mixer. The optimum compounding conditions at 90 rpm were a temperature of 165degreesC and a mixing time of 10 min. Therefore, a short compounding time, appropriate mixing temperatures, and a moderate rotation speed improved the compounding quality of the modified blends and the dynamic mechanical properties of the resultant composites. The melt torque and blend temperature followed a polynomial relationship with the loading ratio of the wood fiber. The highest melt torque and blend temperature were obtained with 50% wood fiber. The coupling treatment was effective for improving the compatibility and adhesion at the interface. The two-step process was better than the one-step process because the coupling agents were more evenly distributed at the interface with the two-step process. (C) 2004 Wiley Periodicals, Inc.