THE THERMODYNAMICS AND WETTING OF REAL SURFACES AND THEIR RELATIONSHIP TO ADHESION

This paper questions the validity of the common practice of applying w ettability experiments to a variety of surface problems, including adh esion. Following from a brief consideration of Gibbsian thermodynamics , wettability and the thermodynamic work of adhesion are discussed wit hin the context of the change of state of the thermodynamic system. Th e results of this discussion are compared with the thermodynamic adhes ion models of Fowkes and Good and with current experimental practice. ft is concluded that wetting experiments do not provide an exact means for determining the reversible work of adhesion, even if adsorption i s absent, and that interpretation must always refer to models such as those proposed by Fowkes and Good. However, it is shown that these mod els imply simplifications and approximations that cannot be assessed f or the error they produce in the thermodynamic work of adhesion.