The structural component of the disjoining pressure in wetting films of tetradecane on glass and mica

As follows from the analysis of experimental disjoining pressure isotherms Pi(h) for the wetting films of tetradecane on mica and glass, these dependences cannot be explained simply by the action of molecular forces. This enables us to assume that the change in the structure of a liquid near the liquid-solid and liquid-gas interfaces and, hence, the structural component Pi(s) of the disjoining pressure should also be taken into account. The values of this component were determined as the difference between the measured values of disjoining pressure Pi and those calculated by the theory of molecular forces Pi(m) at a given film thickness. Parameters characterizing the value and range of action of the structural forces were determined. Assuming the Pi(h) isotherm as the algebraic sum of molecular and structural components, it seems possible to adequately explain the observed regularities and, in particular, the deviation of the Pi(h) isotherms from the theory of molecular forces, which was revealed for a number of similar systems.