J. Gaydos et al., IMPLICATIONS OF THE PHASE RULE FOR CAPILLARY SYSTEMS CONTAINING SURFACES AND 3-PHASE CONTACT LINES WITH SURFACE AND LINEAR CONSTRAINT RELATIONS, Colloid and polymer science, 271(8), 1993, pp. 715-725
The phase rule is generalized to heterogeneous systems with moderately
curved surfaces and linear or line-phase boundaries. It will be shown
that the number of degrees of freedom or variance f of a capillary sy
sem is, in general, larger than that predicted by the classical Gibbs'
phase rule. Restrictions on the value of f for capillary systems is i
ntimately connected with the imposition of mechanical constraints like
the Laplace and Young equations of capillarity. As a direct consequen
ce, it may be shown that the variance for an r-component, three-phase
solid-liquid-vapour system (i.e., a liquid drop on a solid surface) is
different from that of an r-component, liquid-liquid-vapour system. T
his conclusion has important implications for the existence or possibl
e existence of equation-of-state type relations.