WETTING OF WOOD

Thermodynamic work of adhesion, contact angle, wettability and acid-ba se contributions of the wetting of four North American wood species we re determined using the Wilhelmy technique. The wetting angles with wa ter varied from 60 degrees for Sitka spruce to 74 degrees for Douglas- fir. The wood surfaces had a strong acidic character since the greates t interactions for all the wood species occurred with formamide (basic probe) while lesser interactions were obtained with ethylene glycol ( acidic probe). In addition, dispersive and polar surface free energies of wood, gamma(s)(d) and gamma(s)(p) respectively, were determined us ing Wu's simultaneous equations. In general, 75 to 80% of the total su rface free energy of wood was due to dispersion forces. Specific wetta bilities of wood and advancing contact angles in thirty various organi c liquids were also evaluated.