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Ostwald ripening in emulsions

1987; Elsevier BV; Volume: 118; Issue: 2 Linguagem: Inglês

10.1016/0021-9797(87)90492-9

1095-7103

Alexey Kabalnov, A.V. Pertzov, E. D. Shchukin,

Phase Equilibria and Thermodynamics

A study has been made of Ostwald ripening in unstabilized oil/water (o/w) emulsions of 1,2-dichloroethane, benzene, nitrobenzene, toluene, andp-xylene and also in o/w emulsions of 1,2-dichloroethane, stabilized by SDS. A special method for fixing emulsion droplets on a glass surface has been developed for these experiments. Statistical analysis of the experimental data has demonstrated that the changes of the particle size distribution function with time are in accordance with the predictions of the Lifshitz-Slezov theory; i.e., at every moment there are particles with a critical value of radius such that all the larger particles will grow and all the smaller particles will diminish in size; this critical radius coincides with the mean radius. The distribution function of the ratio of the radius to the mean radius is time invariant; the maximum particle radius is 1.5 times the mean. The cube of the mean radius of the particles increases linearly with time. The experimentally observed rates of increase in these values are close to those predicted from the Lifshitz-Slezov theory. In conclusion the role of Ostwald ripening in emulsion coarsening has been discussed.