An experimental study on the influence of a dynamic Stern-layer on the primary electroviscous effect

The most recent theory by Watterson and White for the primary electroviscou s effect of a suspension of charged spherical particles has been extended b y considering the influence of a dynamic Stern-layer. In this work we have tested the theoretical results by measuring the viscosity of polystyrene su spensions in different electrolyte concentrations. Zeta potential values ha ve been obtained by electrophoresis and conductivity experiments using the theoretical approachs by Mangelsdorf and White that include the Stern-layer conductance. In order to obtain the same potential values calculated from these two independent methods, we have fitted the Stern-layer parameters of our systems, These parameters and zeta values have been used to calculate the theoretical viscosity. The theoretical results have been compared with the experimental viscosity data obtained with a semiauthomatic Ubbelohde ca pillary viscometer. We can conclude that the dynamic Stern-layer model used in this work has only a slight influence on the correction of the primary electroviscous effect theory due to Watterson and White. We suggest to stud y the correction supplied by another dynamic Stern-layer model due to Dukhi n and Semenikhin, considering its success when is applied to electrophoresi s. (C) 1999 Elsevier Science B.V. All rights reserved.