Study On The Synthesis And Electrorheological Properties Of Sulfonated Polyaniline

Electrorheological fluid (ER fluid) is a kind of smart material. They havereceived much attention in many industrial fields due to their rheological propertiescan be achieved quickly and reversible adjust under the influence of an appliedelectric field. In this paper, the compositions of ER fluid, the main factors and themechanism of the ER effect have been reviewed. The sulfonated polyaniline (SPAN)with different sulfur to nitrogen ratios (S/N) were synthesized. The electrorheologicalproperties of the polymer-based electrorheological fluids were studied. The maincontents are as follows:Sulfonated polyaniline (SPAN) is prepared by three synthetic methods, and thesulfur to nitrogen ratios (S/N) were0.63,0.94and1.39. The morphology, molecularstructure, thermal stability and electrical properties of these polymers wereinvestigated, and the impact of the sulfonated way on polymer molecular structure andsolubility were investigated. The ER effects of polymer-based suspensions of siliconeoil with different pH and sulfur to nitrogen ratios were investigated. The results showthat three kinds of SPAN-based suspensions of silicone oil exhibited positiverheological effect; the shear stress increases with increasing electric field intensity andthe apparent viscosity decreases with the increasing shear rate. The doping conditioncan be some impact on the ER performance, and the sulfur to nitrogen ratios ofpolymers made great differences on the ER effect, the higher the S/N ratios, thestronger the polarization, the ER effect is more obvious. A quadratic linearlyincreasing relationship between the particle volume fraction and static yield stress ofSPAN-based suspensions of silicone oil was found; static yield stress is higher thanthe dynamic yield stress in the same field conditions and they are both increased withincreasing electric field intensity. Temperature rise help to increase the yield stress.The stability and strength of ER effect are influenced by the electrical conductivity,dielectric constant, sulfur to nitrogen ratios (S/N) and the particle morphologytogether, wherein the S/N ratios are the most important factor.