Electroviscous effect in dilute suspensions of alumina

A study on the electroviscous effect of alumina suspensions has been made. At the low volume fraction of the particles studied here only a first-order effect was detected. Ubbelohde-type capillary viscometers have been used. A simple method to determine the hydrodynamic constant k(1) has been propos ed. The experimental primary electroviscous coefficients corresponding to d ifferent electrolyte concentrations have been compared with two different t heoretical approachs (I, G, Watterson, and L. R. White, J. Chem. Sec. Farad ay Trans. 2 77, 1115 (1981); F. J. Rubio-Hernandez, E. Ruiz-Reina, and A. I . Gomez-Merino, J. Colloid Interface Sci. 206, 334 (1998)) and the results suggest that the presence of a dynamic Stern layer plays a certain role in this effect. (C) 2000 Academic Press.