Stability Ratio-1

The stability of a colloidal dispersion is commonly expressed in terms of the stability ratio. Based on the available theories of coagulation of colloidal dispersions, a novel expression is developed for the stability ratio, accounting for the contributions of both primary and secondary minimum to the overall rate of coagulations. It can be regarded as the result of a combination of the kinetic theory of ideal gas and the Smoluchowski theory with Fuchs' correction. The agreement with experimental data suggested that it is superior to the classical ones in describing the weak dependence of the stability ratio on the particle size and the valance of the counterion, by emphasizing the importance of the secondary minimum in dispersion stability and the complementation between the two modes of coagulation.