Surface and Interfacial Characterization of Wood-PVC Composite: Imaging Morphology and Wetting Behavior<sup>1</sup>
Keywords:
Composites, imaging analysis, maleation, wetting behavior, wood-PVC interfaceAbstract
An imaging technique was used to investigate wetting behavior of wood-PVC composites in this study. Two-dimensional and time-dependent profiles of water droplets on maleated wood surface and wood-PVC interface were observed. Experimental results indicated that coupling agents Epolene E-43 (a maleated polypropylene copolymer with low molecular weight)- and polyethylene-maleic anhydride (PEMA)- treated veneers had a hydrophilic surface, whereas the coupling agent Epolene G-3015 (a maleated polypropylene copolymer with high molecular weight)-treated veneer had a hydrophobic surface. For E-43- and PEMA-treated veneers, a water droplet had an elliptical shape after initial contact with the wood surface. However, a sessile droplet on G-3015-treated specimens was closer to a circular shape. During wetting, contact angle changes on E-43- and PEMA-treated specimens were larger than those on G-3015- treated specimens. Contact angles on maleated specimens with heat treatment and maleated interphases were almost independent of wetting time. Initial contact angle was influenced by coupling agent type, acid number, and retention and directions of wood grains. Initial contact angle decreased with increase of E-43 retention, but it was proportional to PEMA retention. However, it was independent of G-3015 retention. Wettability of fractured wood-PVC interface was similar to that of maleated wood surface with heat treatment. Thus, the interfacial characteristics of wood-PVC interface can be simulated with maleated wood surface with heat treatment.References
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