The primary electroviscous effect in polystyrene latexes with variable charge

摘要

An experimental research of the primary electroviscous effect has been carried out with suspensions of a carboxyl polystyrene latex prepared by using ACPA initiator. The p coefficient of this effect, as given from the corrected Einstein's equation: eta(r) = 1 + k (1+p) phi, has been obtained by measuring viscosities of suspensions as a function of the volume fraction of solid, using an automatic device (Schott Gerate) with Ubbelohde capillary viscometers. These experimental values of the electroviscous effect have been compared with the theoretical predictions proposed by several authors (Smoluchowski, Booth, and Watterson - White). The calculations were made using different zeta potentials obtained from different mobility-zeta potential conversion theories: Smoluchowski, O'Brien-White and Dukhin-Semenikhin. In that way the influence of the zeta potential on the theoretical estimation of the electroviscous effect can be studied. This was done for several electrolyte (NaCl) concentrations, and a maximum in p against [NaCl] was found experimentally. A similar behaviour was obtained theoretically when the residual ionic species present in the solutions due to the adjustment of pH were considered. [References: 20]