Novel viscosity equations for emulsions of two immiscible liquids

Starting from the Taylor equation [Taylor, G. I., Proc. R. Sec. London Ser. , A 138, 41-48 (1932)] for the viscosity of very dilute emulsions, new visc osity equations are developed for concentrated emulsions using the effectiv e medium approach. According to the equations derived in the paper, the vis cosity of concentrated emulsions increases with the increases in the volume fraction of the dispersed phase and the viscosity ratio (K) of the dispers ed phase to the continuous phase. In the limit of K --> co, the equations r educe to the well-known formulas for solids-in-liquid suspensions. The prop osed equations are evaluated in light of a large body of experimental data for concentrated emulsions, covering a broad range of dispersed-phase to co ntinuous-phase viscosity ratio (3.87 x 10(-4) less than or equal to K less than or equal to 3.25 x 10(5)). (C) 2001 The Society of Rheology.