Surface tension and wettability of CCA-treated red maple

The 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 (gamma(s)(AB)) and acid (gamma(s)(+)) components of surface tension for CCA-treatcd wood do not differ much from those of untreated wood. After CCA-treatment, the dispersion (gamma(s)(d)) and Lifshitz-van der Waal (gamma(s)(LW)) components of the surface tension increase while the polar (gamma(s)(P)) and base (y(s)(-)) components decrease. The high contact angles resulting from the water and CCA treatment of wood compared to untreated wood suggest poor wettability. CCA-treatcd wood wetted with phenolformaldehyde (PF) adhesive gave contact angles greater than 90 degrees, i.e., very poor wettability and the time to reach an equilibrium contact angle was three times longer than that for untreated wood.