Wall slip phenomena in oil-in-water emulsions: Effect of some structural parameters

The influence of some structural parameters on wall slip phenomena during t he flow of oil-in-water model emulsions has been investigated using geometr ies with smooth and rough surfaces. A wall slip phenomenon has been quantif ied as the relative difference between the areas under the flow curves obta ined using geometries with both types of surfaces. Experimental results dem onstrate that wall slip effects phenomena vanish as the disperse phase frac tion, the emulsifier content, or the agitation speed applied during the emu lsification process increase. These influences have been related to changes in both droplet size and interparticle interactions. In addition to this, the shear stress range in which wall slip is more important coincides with the region at which a shear-induced deflocculation process occurs. In this region, low reproducible values of the flow curve were obtained by using ge ometries with smooth surfaces. (C) 2001 Academic Press.