Interparticle force conferred by capillary-condensed liquid at contact points: I. Theoretical considerations

Abstract

The accompanying paper (B. Elbirli, L. Vergara-Edwards, and R. W. Coughlin, J. Colloid Interface Sci. 87, 31(1982)) gives experimental results of contrary and diverse trends in the dependence of the shear stress of beds of powders upon humidity. The interpretation of these diverse trends calls upon the theory of capillarity to describe the forces conferred by liquid condensed at points of particle contact. This Part I paper reviews the theory with special emphasis on the role played by particle shape and roughness in the forces exerted by capillary-condensed liquid. Kelvin's equation is introduced to connect the curvature of the liquid surface with its relative vapor pressure. These theoretical aspects and their limitations are evoked and discussed as an introduction to experimental results reported in the Part II paper.