The primary electroviscous effect in polystyrene latexes with variable charge

An experimental research of the primary electroviscous effect has been carr ied out with suspensions of a carboxyl polystyrene latex prepared by using ACPA initiator. The p coefficient of this effect, as given from the correct ed Einstein's equation: eta(r) = 1 + k (1+p) phi, has been obtained by meas uring viscosities of suspensions as a function of the volume fraction of so lid, using an automatic device (Schott Gerate) with Ubbelohde capillary vis cometers. These experimental values of the electroviscous effect have been compared with the theoretical predictions proposed by several authors (Smol uchowski, Booth, and Watterson - White). The calculations were made using d ifferent zeta potentials obtained from different mobility-zeta potential co nversion theories: Smoluchowski, O'Brien-White and Dukhin-Semenikhin. In th at way the influence of the zeta potential on the theoretical estimation of the electroviscous effect can be studied. This was done for several electr olyte (NaCl) concentrations, and a maximum in p against [NaCl] was found ex perimentally. A similar behaviour was obtained theoretically when the resid ual ionic species present in the solutions due to the adjustment of pH were considered.