On the enhanced sedimentation stability and electrorheological performance of intelligent fluids based on sepiolite particles

Abstract

Electrorheological fluids are intelligent materials with the potential for use in a breadth of applications. However, their utilization has been restricted due to poor sedimentation stability and limited performance in the presence of an electric field. Our study investigates the possibility of employing sepiolite particles with their thickness in nanometres to enhance the sedimentation stability of electrorheological fluids. Indeed, the high aspect ratios of such particles have the potential to heighten any electrorheological effect. The rheological properties of the fluids were gauged via steady shear and oscillatory shear tests, in the absence or presence of an external electric field. The electrorheological performance of the systems was further analysed with the aid of dielectric spectroscopy. A test sample containing the greatest amount of sepiolite particles (15 wt%) in a silicone-oil based system was observed to create a solid gel-like structure that completely suppressed sedimentation of the particles; thus, its sedimentation ratio after 200 h was equal to 1. Viscoelastic moduli obtained during measurements for amplitude sweep in the absence of an electric field confirmed a certain extent of elastic behaviour, while the resultant structure exhibited a relatively solid characteristic. © 2020 Elsevier B.V.