Analysis of the capillary forces between two small solid spheres binded by a convex liquid bridge

This work deals with a theoretical study of convex liquid bridges, where solid particles are partially wetted by an amount of liquid whose profile is convex. In our analysis, we adopt a two particle model assuming that the solids are spherical and with the same size and properties, and that the liquid meniscus features an arc-of-circumference contour. We analyze different parameters which govern the liquid bridge: inter-particle separation, wetting angle and liquid volume. The results are compiled in liquid volume-wetting angle diagrams in which the regions of existence of the bridge are delimited in terms of maximum and minimal inter-particle distances. The capillary force is found to present both attractive and repulsive characters for wetting angles smaller and higher than 90 degrees. A map delimiting this force character is also presented. (C) 2009 Elsevier B.V. All rights reserved.