Surface Characterization of Chemically Modified Wood: Dynamic Wettability1
Keywords:Chemical modification, contact angle, decay and spreading ratios, dynamic wettability, kinetics of wetting, wetting models, yellow-poplar veneer
AbstractDynamic wettability of chemically modified yellow-poplar veneer was investigated with sessile water droplets in this study. Dynamic contact angle, decay ratio, spreading ratio, and their changing rates (the wetting slope and K value) were used to illustrate the dynamic wetting process. Dynamic contact angle (α) and droplet height decay ratio (DRh) followed the first order exponential decay equation, whereas the droplet base-diameter spreading ratio (SRφ) fitted the Boltzmann sigmoid model. Wetting behavior of Epolene G-3015 [a maleated polypropylene (MAPP) copolymer with a high molecular weight]-treated wood surface was independent of the retention and wetting time. The retention effect on wetting slopes of >, DRh, and SRφ on poly(ethylene and maleic anhydride) (PEMA)-treated specimens was opposite to that on Epolene E-43 (a MAPP copolymer with a low molecular weight)-treated specimens. Based on these two models, the wetting slope and K value were used to interpret the kinetics of wetting. Therefore, these methods were helpful to characterize the dynamic wettability of wood surfaces modified with different coupling agents.
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