In-situ sol-gel method to prepare colloidal hybrids of surfactant modified polysaccharide and titanium oxide has been presented, and experiments indicated that these highly ER active particles exhibited a remarkable ER effect. The static shear stress can be up to 37 kPa (shear rate 5 S-1) under DC field of 4 kV/mm at room temperature, well above that of simple blends of starch and TiO2. In the meanwhile, temperature dependence and sedimentation stability were also greatly improved. Based on recent experimental facts, we find that dielectric properties and surface (interface) activity are two necessary conditions fulfilling the requirement of high ER activity. Adequate grinding of particles with oil can effectively enhance the shear stress, which may be owed to the decline of the activation energy needed for restructuring. It has provided us a new horizon for preparation of excellent ER materials and further studies should be continued to make. (C) 2002 Elsevier Science B.V. All rights reserved.
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northwestern polytech univ, dept appl phys, inst electrorheol technol, xian 710072, peoples r china. acad sinica, int ctr mat phys, shenyang 110015, peoples r china.;zhao, xp (reprint author), northwestern polytech univ, dept appl phys, inst electrorheol technol, xian 710072, peoples r china
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