Surface Tension and Wettability of CCA-Treated Red Maple
Keywords:Hardwood, <i>Acer rubrum L</i>, red maple, chromated copper arsenate (CCA), adhesion, wettability, phenol-formaldehyde adhesive, contact angle, critical surface tension, surface free energy, dispersion component, polar component, acid-base component, Lifshitz-van der Waal component
AbstractThe wetting properties of untreated, water-extracted and chromated copper arsenate (CCA)-treated red maple were characterized by contact angle measurements. Conventional experimental and mathematical modeling were employed to evaluate the wetting parameters. Zisman's critical surface tensions, and both acid-base (γABs) and acid (γ+s) components of surface tension for CCA-treated wood do not differ much from those of untreated wood. After CCA-treatment, the dispersion (γds) and Lifshitz-van der Waal (γLWs) components of the surface tension increase while the polar (γps) and base (γ-s) components decrease. The high contact angles resulting from the water and CCA treatment of wood compared to untreated wood suggest poor wettability. CCA-treated wood wetted with phenol-formaldehyde (PF) adhesive gave contact angles greater than 90°, i.e., very poor wettability and the time to reach an equilibrium contact angle was three times longer than that for untreated wood.
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