Water Absorption Behavior of Composites from Sawdust and Recycled Plastics

Abstract

The water absorption of wood plastic composites (WPCs) prepared from sawdust and virgin and/or recycled plastics (HDPE and PP) was studied. Wood flour was prepared from sawdust and mixed with different virgin or recycled plastics at 50% by weight fiber loading. The mixed materials were compression molded into panels. Long term water absorptions of manufactured WPCs were evaluated by immersing them in water at room temperature for several weeks (up to 1750 h). Water diffusion coefficients were also calculated by evaluating the water absorption isotherms. Results indicated that the maximum water absorption and diffusion coefficients increased by increasing the proportion of recycled HDPE and/or PP. Time to reach saturation also decreased at higher recycled plastic contents. Water absorption of the studied composites was proved to follow the kinetics of a Fickian diffusion process.