ABSTRACT
The determination of liquid-liquid interfacial tension has been used to test various theories for interfacial tension [1], Recently, Kwok and Neumann [2, 3] have determined the interfacial tensions for a series of liquids with the axisymmetric drop shape analysis (ADSA) method and they found that there were deviations between the calculated and measured results. Consequently, they questioned the validity of the acid-base approach developed by van Oss, Chaudhury and Good (VCG) [4, 5], The purpose of this paper is to show that these deviations are to be anticipated and that the VCG approach is theoretically sound. In particular, we will demonstrate that for initially immiscible liquid pairs, the equilibrium interfacial film pressure, (тгј)е, is the cause of the anticipated deviation [6]; and this surface-chemical factor has never been considered before.
