Role of surface treatment on water absorption of poly(vinyl chloride) composites reinforced by Phyllostachys pubescens particles

Water absorption is one of key parameters in quality assessment of wood-plastic composites. The influence of surface treatment of lignocellulosic particles on water absorption of composites made from poly(vinyl chloride) (PVC) and moso bamboo (Phyllostachys pubescens) particles was studied. The effect of modification with three kinds of chemical treatment agent (alkali, silica and oxidant) on particle surface was examined. The concentration and pH values of the agent aqueous solutions were analyzed and their relationships with water absorption, porosity ratio, thermal property, micro-structure and hemicelluloses content were evaluated. Results showed that pH values of aqueous solutions had little impact on water absorption of the composites while the types of treatment agents did. Alkali treatment lowered the content of hemicelluloses in moso bamboo particles and thus reduced corresponding water absorption. Water resistance improvements of silicate or oxidant treated particles reinforced composites were due to changes of porosity ratio. In general, surface treatment improved water resistance of moso bamboo particles reinforced PVC composites. Compared with the other two agents, sodium bisulfite enhanced the compatibility between cellulose particles and granulated PVC.