ANNUAL TRANSACTIONS OF THE NORDIC RHEOLOGY SOCIETY, VOL. 13, 2005

The zeta potential (ζ) of 2-vol % and 43-vol % suspensions of a commercial α-alumina powder has been measured using the electroacoustic technique called “ESA” and found to be in good agreement with values reported previously from micro-electrophoresis measurements. An increasingly negative ζ value was observed through semiautomatic addition of solutions of a polyelectrolyte (polyacrylic acid) dispersant Dolapix CE64 (Zschimmer & Schwarz, Germany) that is ethanolaminic salt of citric acid. The average particle size (d50) obtained from laser light scattering Mastersizer (Malvern Instrument, UK) compared and showed the effect of dispersant, also coagulation near the isoelectric point. The results illustrate the efficacy of the electroacoustic technique for examining colloidal dispersions at different concentrations