Electrorheological behavior of carbonaceous particle-based suspensions

Using three different carbonaceous particles, we investigated the electrica l and rheological properties of several ER fluids. Each of the carbonaceous particles, prepared From different treatment methods, possesses a differen t oxygen content or degree of crystallinity. These materials were prepared from mesophase pitch and were cationically polymerized with naphthalene and HF/BF3 at high temperature (500 similar to 700 degreesC). Special focus wa s placed on the variables affecting ER properties, including current densit y, temperature, electric field strength, and volume fraction of the particl es. Rheological properties were measured by a rotational rheometer equipped with a high voltage generator. To investigate the durability of the carbon aceous ER fluids, we also measured changes in shear stress, shear viscosity , and current density at the shear rate of 50 sec(-1) and different tempera tures (from 20 to 100 degreesC). Good thermal and electrical stability of t he carbonaceous particle-based ER suspensions were observed.