DIELECTRIC-RELAXATION IN POLYSTYRENE SUSPENSIONS - EFFECT OF IONIC-STRENGTH

The study of the conductivity and dielectric response of colloidal suspensions in a.c. fields of frequency omega can help in improving our understanding of the electrical characteristics of the solid-liquid interface in colloidal systems. In fact, the strong dielectric dispersion shown by such systems at low frequencies is intimately related to the polarization of the double layer surrounding the particles. In this work, we present recent data on the real and imaginary parts of the conductivity and dielectric constant of spherical polystyrene suspensions as a function of the frequency of the applied field, and of KCl concentration in the dispersion medium. The conductivity and dielectric increments are compared to the predictions of accepted theoretical models. The qualitative agreement between both types of data is excellent, although the experimental results are significantly higher than the theoretical ones. Reasons for such discrepancies are discussed in the light of recently reported determinations.