Correlation of the dispersed particles surface properties with the electrorheological response

A set of oxidized polyacrylonitrile materials of different surface situations were employed to examine how the dispersed particles surface properties influence the electrorheological (ER) response. The shear stresses of these ER fluids were found to peak for the surface tension and the surface polarity of the dispersed particles, which could be qualitatively understood with our recent finding that the large dielectric loss, along with the large dielectric constant, are argued for good ER performance. Our findings have the direct implication that the ER effect would be most likely improved by means of certain surface modification methods, especially some chemical methods like the molecular design method, which perhaps can provide a good approach to develop the expected ER solid materials. Our results would also be significant for selecting ER solid materials and understanding the ER mechanism. A further theoretical work should be performed in the future. (C) 1996 American Institute of Physics.