Effect of Coupling Agent on Hygroscopic Thickness Swelling Rate of Wood Based Composites

The effect of coupling agent content on the hygroscopic thickness swelling rate of polypropylene composites was investigated in this study. To meet this objective, the wood flour was compounded with polypropylene and coupling agent in an internal mixer; then the samples were fabricated by injection molding. The concentration was varied from0 to 4% for coupling agent. A swelling model developed by Shi and Gardner (2006) was used to study the thickness swelling process of composites, from which the parameter KSR can be used to quantify the swelling rate. The resultsindicated that the swelling model provided a good prediction of the hygroscopic thickness swelling process of polypropylene-wood flour composites immersed in water. A good linear relationship was fit between KSR and coupling agent contents. The SEM revealed a positive effect of coupling agent on interfacial bonding between sawdust flour and polymer matrix

Keywords:

Hygroscopic thickness swelling rate , Swelling model , Coupling agent , Polypropylene