Modeling Pendular Liquid Bridges with a Reducing Solid-Liquid Interface

Liquid bridges formed between particles of dissimilar surface properties are important in many processes involving the handling of powders in mixtures. For instance, growth kinetic models for wet granulation frequently incorporate the evolution and resistance to breakage of individual liquid bridges between particles in a statistical form. These models generally propose a confusing definition of liquid-to-solid contact angles. Taken as a single thermodynamic value, they typically neglect the influence of wetting hysteresis on the liquid bridge. In this paper, a simple model based on the interfacial energies is proposed for the evolution of liquid bridges when one solid-liquid interface reduces. This receding process is well described by a balance between the adhesion energy of the bridge liquid on the particle surface and the capillary energy stored by the liquid free surface. The extent of solid-liquid interfacial area reduction can hence be predicted from the initial liquid bridge configuration. The liquid bridge shape is approximated by a parabolic curve, which is validated from the good agreement between measured and calculated contact angles or liquid-vapor interfacial area. Copyright 2000 Academic Press.