Materials for Er Fluids

Abstract

Recent improvements in the physical understanding of ER fluids have led to the rational design of new ER materials with improved properties. This paper gives an overview of several recent developments in the formulation of ER fluids, concentrating on new particulate phases for ER dispersions. Examples of homogeneous ER fluids are also discussed. The trend leading to designed ER dispersions is demonstrated by a new class of electrorheological fluids based on non-aqueous polyurethane dispersions. The fluids exhibit an attractive combination of properties: low viscosity, high ER effect, and low conductivity. The dispersed phase consists of a specially developed polyurethane elastomer which solvates and stabilizes metal salts. The polymer network density influences the mobility of the dissolved ions, allowing a surprising degree of control over the ER effect. Properties such as the field strength dependence of the ER-effect, switching response, and conductivity of these fluids correlate directly with changes in the polymer structure. Electrorheological measurements in a couette viscometer (shear-mode) and in a model shock absorber (flow-mode) using a commercial polyurethane-based fluid show that the ER effect is also dependent upon the shearing geometry.

Enhanced Stimuli-Responsive Electrorheological Property of Poly(ionic liquid)s-Capsulated Polyaniline Particles

“…Among various organics, polyelectrolyte is most frequency studied due to its low cost, facile preparation, and high ER effect. Some classic polyelectrolytes, such as poly(sodium styrene sulfonate), poly(lithium methacrylate), and so on [ 19 ] have been used as the dispersed phase of ER suspension. However, they usually need to absorb a small amount of water or moisture to activate ER effect.…”

Bingham characteristics of polymer‐based electrorheological fluids with different electrode gaps and materials

“…On the other hand, a dry‐based polyurethane ER fluid (ERF‐2) was purchased from Bayer (Germany); polyurethane‐based ionic conductor particles were used as the dispersed phase of the ER fluid. It was reported that polymers based on functional polyethers as well as aliphatic polyesters and polycarbonate were crosslinked with isocyanates to form polyurethane elastomers with the dimensional stability required for the dispersed phase of an ER fluid in silicone oil 34…”

INVESTIGATION OF THE EFFECT OF ELECTRIC FIELD ON CO2 ABSORPTION IN WATER/Fe3O4 NANOFLUID

“…The relative viscosity of nanofluids increases with electric field intensity. Bloodworth and Wendt (1995) and Hasley (1992) reported an increase of suspension viscosity due to exerting an electric field. They attributed this effect to the chain formation of the particles in the suspension induced by their polarization in the electric field.…”