| Abstract
| - The existing viscosity−concentration equations for concentrated emulsions of nearly sphericalnoncolloidal droplets are first reviewed. The equations of emulsion relative viscosity ηr vs volumefraction of dispersed-phase φ existing in the literature are characterized as single-parameterequations because viscosity ratio (ratio of dispersed-phase viscosity to continuous-phase viscosity)is the only parameter in the equations. The equations are evaluated in light of a large body ofexperimental data for concentrated emulsions, covering a broad range of viscosity ratios. Theexisting equations generally give good predictions of relative viscosity only at low values of φ (φ< 0.2). Several new equations are proposed and evaluated with experimental data. The proposedηr vs φ equations are characterized as two-parameter equations because they contain twoparameters, namely, the viscosity ratio and φm, the maximum packing volume fraction of droplets.The proposed equations generally show good agreement with the experimental data.
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