Electrorheology of a zeolite/silicone oil suspension with dc and ac fields

Abstract

The electrorheology of a zeolite/silicone oil suspension with direct current (dc) and alternating current (ac) electric fields was determined at room temperature. The shear yield stress changed only slightly with the field frequency, but the current density increased considerably. Good agreement occurs between the experimental results and those predicted by our model for both the shear yield stress and the current density. This study shows that there is a significant electrorheological (ER) effect over a large frequency range when a suspension has both a high conductivity ratio and a high dielectric ratio of the particles to the host oil.

Monodisperse poly(2-methylaniline) coated polystyrene core–shell microspheres fabricated by controlled releasing process and their electrorheological stimuli-response under electric fields

“…This agrees with the conduction model [37], which suggests that the ER effect with a DC field is induced by a mismatch of the conductivity of the particles and medium fluid. The G 0 value of the ER fluids measured at different electric field strengths slightly increased over a broad frequency region, from which the viscoelastic solid behavior of the ER fluids could be predicted due to the formation of chain-like structures under an electric field.…”

Rheological properties of a model colloidal suspension under large electric fields of different waveforms

“…This is due to the fact that the majority of investigations are performed when the fluid is excited by a single-frequency sinusoidal AC field or by a DC one, and only a limited number of publications consider a detailed investigation over a range of frequencies [17][18][19][20][21][22]. Furthermore, to our knowledge, no systematic studies have been performed on the role of the waveform (at different amplitudes and/or frequencies) of the external electric field on the ER effect.…”

Self-assembly of nanoparticles into heterogeneous structures with gradient material properties

“…The relation between the dielectric permittivity and dielectric constant is ε A = ε rA ε 0 , where ε 0 = 8.85 × 10 −12 F/m is vacuum permittivity. The humidified zeolite particles used in our simulations have a dielectric constant of ε rB = 23.7 and a conductivity of σ B = 1.5 × 10 −5 S/m [34]. The dielectric constant and conductivity for silicone oil are ε rm = 2.54, and σ m = 10 −13 S/m [33], respectively.…”