Electrorheological analysis of colloidal dispersions of aluminum oxide and silicone oil

The electrorheological properties of colloidal dispersions of aluminum oxide nanotubes and nanoparticles in silicone oil were investigated. The shear storage modulus of colloidal dispersions containing 5 wt% of aluminum oxide nanotubes increased by four orders of magnitude upon the application of an external electric field of as low as 400 V/mm. The storage modulus of the nanotube systems increased further by increasing the concentration of nanotubes. The electrorheological response of aluminum oxide nanoparticles dispersions was significantly lower than that of the dispersions containing the same weight fraction of aluminum oxide nanotubes at the same external electric field. This result reflects the effect of shape anisotropy on the electrorheological features of colloidal dispersions.