Dielectric spectroscopy of high-solids, styrene-butadiene latex dispersions

This paper presents the application of electrochemical impedance spectroscopy as an interfacial electrokinetic characterization tool for high-solids, carboxylated, styrene-butadiene latex dispersions. The frequency-dependent conductivity and the characteristic relaxation frequency (CRF) were studied for both ''as-produced'' latexes and latexes purified through an ion-exchange resin. CRF is a measure of the speed with which the interface perturbation disappears, with high values of CRF indicating a more rigid double-layer structure. For the as-produced and purified latex samples, the magnitude of both conductivity and CRF increased with increasing latex particle concentration (percent solids), added electrolyte level, and decreasing latex particle size. The CRF showed a minimum with increasing pH. Latex particle concentration, electrolyte, and pH appear to affect latex dispersion dielectric properties in a predictable manner consistent with the understanding gained from rheological measurements. (C) 1997 Academic Press.