Prediction and Evaluation of Emulsion Stability with Ultracentrifugal Stress

Synopsis--The hypothesis that the SVEDBERG RELATIONS for the FLOTATION of OIL PARTICLES in high ratio OIL/WATER EMULSIONS do not hold is substantiated. ULTRACENTRIFUGATION of such emulsions introduccs a nonlinearity into log oil cicarance rs. time plots which is due to the subsequent sweep-out of the heterogencous discontinuous phase since slippage and stratification of particles are blocked. NONSTRATIFIED CREAMS demonstrate an initially apparent first-order process of large particle drainage from. the cream concomitant with continuous drainage of heavier surfactant. The final rate of oil separation is constant and reflects that rate-determining coalescence is at the cream-oil interface, that the ultimate cream is a tightly packed, homogeneously particulate mass with mininmm continuous phase. This was substantiated by microscopic examination. In addition to reproducible preparative methods, sensitive analytical methods have been devcloped to assay the SURFACTANT and oil concentrations in various cmulsions.