Electrorheological properties of micro balloons

The relation between the densities of particles in electrorheological (ER) fluids and the electrorheological effects was investigated. Microballoons, used as particles, were dispersed in silicon oil, which was used as the base fluid. Shear stresses as a function of shear rate were measured for ER fluids in the range of 0-1000 V/mm using a parallel-disk-type rheometer. The shear stresses under AC fields were different from those under DC fields for all samples. The shear stresses for the sample containing particles with densities much lower than that of the base fluid and the sample containing particles with densities slightly lower than that of the base fluid were lower than those for the sample containing particles with densities higher than that of the base fluid. The shear stress was the highest for the sample containing a mixture of these particles. The experimental results demonstrated that the distribution of particles between electrodes was important for obtaining high shear stress.<
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