Electro-viscoelasticity of agarose based electrorheological fluids

Abstract

In this article, we report a new class of colloidal, micrometer-scale agarose powder based organic electrorheological (ER) fluids and its ER and viscoelastic characteristics. The steady shear ER characteristic of the colloids shows enhancements in the yield stress of the fluid, and yield stress values approaching ∼1 kPa have been noted. The ER hysteresis and electro-thixotropy illustrate that the microstructure of the colloids under field effects is able to withstand dynamic and impact stresses with good repeatability. The electro-creep strain and stress relaxation characteristics of the colloids show transition to the elastoviscous state with an increase in electric field strength. The oscillatory shear ER characteristic of the colloids shows field induced transition from a fluid-like nature to solid-like nature. Atypical regimes of loss and regain in viscoelastic nature are noted for the colloids under different field constraints. The viscoelastic dissipation and complex viscosity characteristics are also discussed for utilitarian aspects. Mathematical analysis reveals that the electric field induced viscoelastic, creep strain, and stress relaxation signatures of the colloids conform to fractional derivative elastoviscous models. The present findings may find significant implications toward the design and development of organic particle based ER fluids.