Journal of colloid and interface science vol:165 issue:1 pages:212-220
The dielectric properties and the conductivity of carbon black suspensions in mineral oil have been investigated during shear. The presence of shear modifies the properties considerably. The experimental results for this reversibly flocculated system show a shear-rate-dependent power law behavior of the dielectric susceptibility in a frequency range above 100 Hz. A structural explanation for this dielectric behavior is suggested. At lower frequencies resonance phenomena are observed. At a shear-rate-dependent frequency a maximum polarization is found, while time-dependent measurements in a constant electric field show a slight minimum in conductivity. Measurements performed in the time domain and in the frequency domain are in quantitative agreement. The results illustrate the usefulness of dielectric spectroscopy in analyzing the structure of flocculated suspensions under shear. (C) 1994 Academic Press, Inc.