EFFECT OF OIL VISCOSITY ON THE RHEOLOGY OF OIL-IN-WATER EMULSIONS WITH ADDED SOLIDS

This paper reports an experimental study on the effect of oil viscosit y on the rheology of oil-in-water (o/w) emulsions with added solids. F our oils having a viscosity range of 0.0024 to 306 Pa . s were used. T he size ratio of the solids to oil droplets was varied from 2 to 16. T he addition of smaller size solids to the emulsions yielded a higher v iscosity than that of larger solids at the same solids volume fraction . However, when the solids were sufficiently large such that the emuls ions behaved as a continuous phase towards the solids, the viscosity o f the emulsion-solids mixtures tended to be independent of the solids size. The critical size ratio of the solids to oil droplets, above whi ch the emulsions behaved as a continuous phase towards the solids, inc reased with the oil viscosity. The critical size ratio varied between 3 and 10.