A comparison of compounding Processes for wood-fiber/thermoplastic composites

This study was carried out to investigate the feasibility of developing a continuous compounding process for wood-fiber/thermoplastic composites using the Szego mill, a unique, high speed planetary ring-roller grinding mill. Prior to compounding, air-dried sawdust was ground to evaluate the grinding effect in the mill. As the feed rate and the mill speed increased, the particle size increased and decreased, respectively. Sawdust particles were successfully compounded in linear low-density polyethylene using the Szego mill without any major heat application. A Gelimat mixer, used for the compounding of wood fiber through a high-shear thermokinetic mixing process, was also employed for comparison. Composites with 30 wt% wood fiber were prepared by both compounding processes, and their mechanical properties were evaluated. The use of a compatibilizer in compounding improved the mechanical properties of the composites regardless of the compounding process. The composites prepared by Szego mill compounding showed comparable strength properties with their counterparts from the Gelimat mixer. Power consumption during mill compounding was in the range of twin-screw extruder processing.