On the Calculation of Dispersion and Polar Force Components of the Surface Free Energy

Abstract

Abstract Contact angle measurements have been widely used1–6 to calculate the values of the dispersion force, γ d s , and polar force, γ p s , components to the total surface free energy of a material using a derivation originally proposed by Kaelble.2 In this analysis a pair of simultaneous equations is derived which for two liquids, i and j, on a common solid surface may be written as: where α is the contact angle of the liquid on the solid surface. Thus, if the values of α, γ d l , γ p l and γ l (where γ l = γ d l + γ p l ) for the two liquids are known, these equations may be solved to yield the dispersion, γ d d ;, and the polar, γ d s , force components to the surface free energy of the solid surface. The total surface free energy, γ s , is then simply the sum of these components.