Effect of chemical blowing agent on the hygroscopic behavior of HDPE/rice husk flour composites

Abstract

The effect of chemical blowing agent on the cell morphology and long-term water absorption and thickness swelling of composites based on high-density polyethylene/rice husk flour were studied in this research. Composite materials containing high-density polyethylene, rice husk flour, chemical blowing agent and coupling agent were melt compounded using twin-screw extruder. Then, the samples were foamed via batch process using a compression molding machine. The results showed that the water absorption, thickness swelling, cell size and average cell density of composites increased by addition of chemical blowing agent. The mechanism of water absorption of the foamed wood plastic composites under study followed the kinetics of a Fickian diffusion process. Furthermore, adding the chemical blowing agent had effect on water diffusion coefficients and swelling rate parameter ( KSR) of composites.