Concentrated emulsions. 3. Studies on the influence of continuous-phase viscosity, volume fraction, droplet size, and temperature on emulsion viscosity

Abstract

Explosive-type emulations with internal-phase fractions from 0.74 to 0.92 were studied to quantify the effects of average droplet size, continuous-phase viscosity, volume fraction, and temperature on emulsi viscosity measured at low rates of shear. Plots of emulsion viscosity vs volume fraction of thr dispersed phase (φ) were obtained at 80 °C for two different emlsions varying in continuous-phase composition, but having constatnt droplet size profits. Emulsion viscosity increased steeply as the internal phase increased, but varied inversely with average droplet radius. the effect of drplet size became more prominent at higher values of φ. the viscosity of the emulsion (when corected for the viscosity of the continuous phase) increased approximately linearly with increased internal phase when drop size distribution was held constant. A mathematical analysis is given that ascribes the inrease to droplet distortion. At low shear, the studied emulsions exhibited Boltzmann temperature dependene to flow (E = 2-6 kcal/mol) with breaks at 22 and 72 °C, the continuous phase also exhibited a break at 22 °C.