Effects of nano additives on the rheological behavior of fumed silica filled polyethylene glycol based shear thickening fluid

Abstract

This study presents a systematic rheological study on shear thickening fluid (STF) to determine the behavior and effects of fumed silica and different additives concentration on the shear-thickening behavior and the critical parameters responsible for thickening behavior. A stable STF suspension was prepared by adopting the sono-chemical homogenization technique, which enabled the complete elimination of water contamination and air bubbles from the STF suspension. Due to the presence of additives, the discontinuous shear thickening (DST) behavior was achieved even at low fumed silica concentration. The critical parameters, i.e., critical shear rate (CSR), peak viscosity, and shear thickening ratio (STR), were strongly influenced by different additives and their concentrations. Increasing the concentrations of the additives even in less proportion in the virgin shear thickening fluid (V-STF) significantly increases the thickening behavior and the peak viscosity and decreases the CSR. Further, a possible mechanism for shear thickening has been reported based on the effects of additives and their concentrations to understand the rheological behavior of these STF suspensions. The present study is in agreement with the hydro-cluster theory for the shear thickening behavior and particle friction interaction theory for the discontinuous shear thickening. In addition, the energy dissipation by the STF suspensions was also obtained from the oscillatory rheological test.