Viscous properties of polymer‐thickened water‐in‐oil emulsions

Abstract

AbstractThe viscous flow properties of polymer‐thickened water‐in‐oil emulsions were measured using a coaxial cylinder viscometer. The emulsions were prepared using deionized water and polyisobutylene in oil solutions. Three different molecular weight polyisobutylenes (Vistanex MML‐140, Vistanex MML‐100, and Vistanex MML‐80) were studied. The effects of polymer concentration and water (droplet) concentration on the flow properties were determined. The polymer concentration varied from 0 to 3.96% by weight based on the oil phase whereas the water concentration varied from 0 to 80% by volume (based on total emulsion volume). The polymer solutions behaved like non‐Newtonian Ellis model fluids. At low water concentrations, the flow curves for emulsions were similar to their suspending medium (polymer solution). At high values of water concentration, emulsions clearly exhibited a yield stress. The yield stress increased with both water and polymer concentrations. The shear stress/shear rate data for the emulsions possessing a yield stress were described adequately by a modified Herschel‐Bulkley model. A comparison was also made of the relative viscosities of emulsions having different polymer concentrations. The relative vis‐cosities for polymer‐thickened emulsions were found to be significantly lower than the corresponding values for emulsions without polymer. The correlation of relative viscosity/ concentration data is discussed. © 1993 John Wiley & Sons, Inc.