EFFECT OF SURFACE-PROPERTIES ON THE ADHESION BETWEEN PVC AND WOOD VENEER LAMINATES

The interface between plastic and wood fibers strongly influences the mechanical properties of a plastic/wood-fiber composite. This paper pr esents a means for evaluating the effectiveness of surface treatment o n the wood-fibers in the PVC/wood-fiber composites by investigating th e adhesion between PVC and laminated wood veneers. Wood veneers were f irst treated with gamma-aminopropyltriethoxysilane, dichlorodiethylsil ane, phthalic anhydride, and maleated polypropylene for surface modifi cation. The chemical modification made on the wood surfaces was then c haracterized using different complementary surface analytical techniqu es: X-ray photoelectron spectroscopy and surface tension measurements. The surface tension was determined from the equation of state for int erfacial tensions and the measured contact angles of glycerol sessile drops on the wood veneers (both untreated and treated) and on WC using the Axisymmetric Drop Shape Analysis-Contact Diameter (ADSA-CD) appro ach. The adhesion property was evaluated by measuring the tensile shea r strength of single lap joints between two wood veneers bonded with a WC film. The adhesion between WC and wood veneer laminates was signif icantly improved when wood veneers were treated with amino-silane, whi le no improvement was observed for the other adhesion promoters. Our e xperimental results indicate that matching the surface tension is not sufficient to ensure good adhesion between WC and wood veneers.