Thermodynamics and dynamics of pure interfaces

The paper derives, on a coherent postulatory basis, the basic set of equations needed to completely describe the thermodynamics and dynamics of pure interfaces. This set comprises: the equilibrium constitutive equation giving the surface tension as a function of the absolute temperature; the interface balance equations for momentum and internal energy; the non-equilibrium constitutive equations giving the surface transport coefficients (two viscosity coefficients and a thermal conductivity coefficient) as function of the absolute temperature. A discussion of the interface balance equations considered as boundary conditions for the field equations pertaining to the adjoining bulk phases is given and the inadequacies of previous ad hoc formulations pointed out.