Electrorheology of Diamond/PDMS Nanofluids in Steady and Oscillatory Shear

Abstract

The rheological properties of diamond (< 10 nm) in silicone oil (PDMS) were analyzed using steady shear and oscillatory shear measurements. Unlike micron sized diamond suspensions these suspensions were non Newtonian and showed strong viscoelastic behavior without the electric field applied. Furthermore these nanodiamond mixtures showed sigmoidal behavior for their apparent viscosity as the shear rate is increased without the electric field applied. When the electric field was applied the apparent viscosity of the mixtures increased by an order of magnitude at lower shear rates. The effects of electric field and concentration on diamond rheology are both examined. The rate of shear thinning for the mixtures is high when the applied electric field is high. At high shear rates for the mixture the electric field does not have much effect. The flow curve was described by the Herschel-Bulkley model. Yield stress values obtained from the model gives an important relationship between yield stress, electric field and concentration, that is τ μ En and where 0.8 < n < 1.3.

Keywords

• electrorheology
• carbon
• diamond
• nano powder
• yield stress
• electrorheological fluid