ELECTRORHEOLOGICAL EFFECT OF SUSPENSIONS OF POLYELECTROLYTE PARTICLES DISPERSED IN A HALOGENATED PARAFFIN

The electro-rheological effect (ER effect) of suspensions of polyelectrolyte particles dispersed in a non-conducting oil was studied theoretically as well as experimentally. In one theoretical approach, a yield stress reflecting the ER effect was evaluated based on a model in which the particles made point-dipoles in electric fields and then formed many chains due to dipole-dipole interactions at a short range between electrodes. The yield stresses calculated using this model were in qualitative and quantitative agreement with experimental results on a suspension of crosslinked polymethacrylic acid (PMA) cobalt(II) salt particles dispersed in a halogenated paraffin. However, the ER effect of a suspension of the PMA sodium salt particles was not qualitatively similar to the model. The yield stress that could be attained by the suspension of the sodium salt particles was about an order of magnitude larger than the calculated result.