Conclusions
Maximum water absorption and the highest diffusion coefficient were found when mAC was applied at 2.0 wt%. The water absorption mechanism of the foamed PVC/rice hull composites followed the kinetics of Fickian diffusion theory. A slight increase in both the flexural modulus and the strength
was observed in all the PVC/rice hull foam compositions due to the leaching of some PVC additives. Microscopic observation on the surfaces of the foamed composites revealed abundant surface openings depicting the passages of water diffused into the PVC/rice hull foamed composites.