Kim, YD Nam, SW 2024-01-21T07:40:21Z 2024-01-21T07:40:21Z 2021-09-02 2004-01-01 0021-9797 https://pubs.kist.re.kr/handle/201004/137944 Surfactants influence the electrorheological (ER) response in two ways. At low surfactant concentrations, they enhance the ER response by enhancing the particle polarizability; at high concentrations, the response degrades (nonlinear ER response). The nonlinear ER behavior arises from the formation of surfactant bridges between the particles at high surfactant concentrations. A surfactant bridge-model was introduced to explain the nonlinear behavior (tau(0) proportional to E-n, n approximate to 1) of surfactant-activated ER suspensions when surfactant bridges were formed between the particles. Here, the surfactant bridge model is extended for the prediction of both the linear and nonlinear ER behaviors of surfactant-activated ER suspensions over the low and high surfactant concentrations (for Brij 30, from 0 to 7 wt%), regardless of the formation of surfactant bridges between the particles. For 20 wt% neutral alumina suspensions in silicone oil activated by Brij 30, the predicted ER behaviors show almost the same Brij 30 concentration and electric field strength dependence. It predicts the linear E-2 dependence of the ER response at low surfactant concentrations and the nonlinear ER behavior at high surfactant concentrations. Also, the estimated yield stresses show fairly good agreement with the experimental data. (C) 2003 Elsevier Inc. All rights reserved. English ACADEMIC PRESS INC ELSEVIER SCIENCE DISPERSIONS RHEOLOGY Extension of the surfactant bridge model for the electrorheological effects of surfactant-activated suspensions Article 10.1016/j.jcis.2003.09.034 1 JOURNAL OF COLLOID AND INTERFACE SCIENCE, v.269, no.1, pp.205 - 210 JOURNAL OF COLLOID AND INTERFACE SCIENCE 269 1 205 210 scie scopus 000187574400027 2-s2.0-0345357113 Chemistry, Physical Chemistry Article DISPERSIONS RHEOLOGY ER suspensions surfactant bridge model nonlinear behavior surfactant-activated suspensions