ELECTRORHEOLOGICAL BEHAVIOR OF CARBONACEOUS PARTICLE-BASED SUSPENSIONS

Using three different carbonaceous particles, we investigated the electrical and rheological properties of several ER fluids. Each of the carbonaceous particles, prepared from different treatment methods, possesses a different 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 (500~700 °C). Special focus was placed on the variables affecting ER properties, including current density, temperature, electric field strength, and volume fraction of the particles. Rheological properties were measured by a rotational rheometer equipped with a high voltage generator. To investigate the durability of the carbonaceous ER fluids, we also measured changes in shear stress, shear viscosity, and current density at the shear rate of 50 sec^-1 and different temperatures (from 20 to 100°C). Good thermal and electrical stability of the carbonaceous particle-based ER suspensions were observed.