Studies on the binary coalescence model - II. Effects of drops size and interfacial tension on binary coalescence time

A binary coalescence model of a two-component system of mixed oil drops in water is established. The original coalescence driving force directly conne cted to the chemical potential difference of the coalesced oil drops has be en investigated under a mimetic "weightlessness" condition. Gravitation is minimized nearly to zero to overcome drop deformation by mixing hydrocarbon compounds and carbon tetrachloride. Any external force out of the drops is reduced nearly to zero, when one liquid drop goes near enough to be tangen tial to another. The coalescence time, defined as the binary coalescence ti me (t(bi-coal)), can be expressed as ink(d)sigma (1/r(1) - 1/r(2)) = k(b)t(bi-coal) + b'. [1] The coalescence phenomenon was first proposed as initiated by chemical pote ntial differences between liquid drops (B. Y. Yu, Ph.D. dissertation, Swiss Fed. lost. Technol., Zurich, 1995). The greater the chemical potential dif ference between two liquid drops, the larger the factor sigma (1/r(1) - 1/r (2)); as a result, the coalescence tendency will increase (i.e., t(bi-coal) decreases). Equation [1], including interfacial tension, drop size differe nce, and thin-film coefficient supported by the experimental data, is quant itatively established. (C) 2001 Academic Press.