Electrorheological properties of micro balloons

In this article, the relation between the densities of particles in electrorheological (ER) fluids and the electrorheological effects was investigated. Micro balloons, 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, which was constructed. The shear stresses under AC fields were different from 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 showed that the distribution of particles between electrodes was important to obtain high shear stress