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Contact angles in thin liquid films. I. Thermodynamic description

1978; Elsevier BV; Volume: 64; Issue: 2 Linguagem: Inglês

10.1016/0021-9797(78)90361-2

1095-7103

J.A De Feijter, J.B Rijnbout, A. Vrij,

Material Dynamics and Properties

Starting from a system consisting of a soap film with its environment as found in practice an analysis is given of the thermodynamics of thin liquid (soap) films. Definitions are given of the film thickness, disjoining pressure, potential interaction energy, etc., in terms of a three-dimensional film description in which the film is thought to consist of a homogeneous volume phase bounded by two Gibbs dividing surfaces. The relations between the film quantities are derived. The influence of a gravitation field on the film properties is treated explicitly. As a result we find that the differences between the excess quantities of the film surface and those of the bulk phase surface, which result from the interaction between the two film surfaces can be found from contact angle and film thickness measurements. It is indicated how the results can be applied in the study of interaction forces.