CONCENTRATED EMULSIONS .3. STUDIES ON THE INFLUENCE OF CONTINUOUS-PHASE VISCOSITY, VOLUME FRACTION, DROPLET SIZE, AND TEMPERATURE ON EMULSION VISCOSITY

Explosive-type emulsions 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 emulsion viscosity measured at low rates of shear. Plots of emulsion viscosity vs volume fraction of the dispersed phase (phi) were obtained at 80-degrees-C for two different emulsions varying in continuous-phase composition, but having constant droplet size profiles. Emulsion viscosity increased steeply as the internal phase increased, but varied inversely with average droplet radius. The effect of droplet size became more prominent at higher values of phi. The viscosity of the emulsion (when corrected 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 increase to droplet distortion. At low shear, the studied emulsions exhibited Boltzmann temperature dependence to flow (E(a) = 2-6 kcal/mol) with breaks at 22 and 72-degrees-C. The continuous phase also exhibited a break at 22-degrees-C.