Shear thinning and shear thickening characteristics in electrorheological fluids

Abstract

The electrorheology (ER) of suspensions based on polystyrene/polyaniline (PS/PANI) core/shell structured microspheres and those based on disk-like zeolite particles at different electric fields and particle volume fractions have been studied, respectively. Both types of ER fluids showed abrupt shear thickening under high electric fields and low shear rates, as well as shear thinning when the shear rate increased. A normalized method that considers the effects of electric field strength, shear rate and particle volume fraction was proposed to compare the rheological curves of the two ER fluids. The curves evaluated from the normalization method showed similar shear thinning at low shear rates and the hydrodynamic effect at high shear rates. Shear thinning represents the structure destroyed by shearing, and shear thickening at low shear regions indicates the dramatic structure change. The particle volume fraction and structure factor effects demonstrate that the mechanical contact between particles and the wall of the electrodes is crucial to the shear strength of ER fluids, indicating an electric/magnetic field modulated friction mechanism of the ER and magnetorheological (MR) effects.

High-Throughput Preparation of Silk Fibroin Nanofibers by Modified Bubble-Electrospinning

“…To the best of our knowledge, the viscosity of solutions increased with the increase of the solution concentration [ 36 ]. And it’s reported [ 37 ] that the fluid shear thinning behavior was enhanced with the increase of solution concentration, and the fluid shear thinning behavior was mainly caused by the orientation of macromolecular chains. With the increase of shear rate, the number of the oriented macromolecular chains increased, which could decrease the viscosity and enhance the shear thinning behavior.…”

Conductive polymers/zeolite (nano-)composites: under-exploited materials

“…More recently, Jiang et al 114 studied the electrorheology (ER) of suspensions based on polystyrene/polyaniline (PSt/PANI) core-shell structured microspheres and those based on disklike zeolite particles at different electric elds and particle volume fractions. For this purpose, monodisperse PSt core particles were rstly synthesized via a dispersion polymerization method, then the ne coating for which by conducting PANI was realized by a swelling-releasing process in an aqueous suspension of the particles by adding aniline monomer.…”

Comparison of rheological behaviors with fumed silica-based shear thickening fluids

“…Another unique aspect is the reversibility of this effect as the STFs will return to fluid state once the shear force is removed or reversed, making it advantageous as a reusable product in applications. Current applications with STFs include scenarios which require energy adsorption from sharp projectiles such as knife or spike attacks [1][2][3][4][5][6][7][8][9][10][11], acoustic and mechanical vibrational dampening control [12,13] and in a passive capacity in other polymeric materials [14][15][16]. The theory of shear thickening includes an order-disorder transition of particles [17,18] and formation of clusters, otherwise known as "hydroclusters" [19][20][21][22] that only form once the applied shear forces overcome particle repulsion forces.…”