The contribution of friction to electrorheological properties of a chrysanthemum-like particle suspension

Abstract

Several studies have proved that a significant electrorheological (ER) effect can be obtained by using particles with hierarchic structures as the dispersing phase. The inter-particle friction and fluid friction caused by the rough surface of the particles plays an important role for their enhanced ER effect. However, the detailed contribution of friction to ER properties remains unclear. We prepare two different ER fluids with chrysanthemum-like particles and spherical particles, respectively. We carry out a low shear velocity oscillation test to separate the friction-induced shear stress from the electrostatic attraction-induced shear stress. The chrysanthemum-like particle-based ER suspension presents much better ER performance than the ER fluid with spherical particles. The larger friction force caused by the rougher surface of the chrysanthemum-like particles is a major reason for the improvement. The contribution of friction to the ER effect depends on the electric field strength. The contribution has a maximum value at a critical electric field.