Effect of Suspended Particle Shapes on Shear Thickening Fluid Behavior

Abstract

Shear thickening fluids (STFs) consist of a particulate dispersed phase suspended in a continuous liquid phase, and they exhibit a dramatic increase in viscosity at shear rates above a critical value. This phenomenon can be influenced by several factors including the particulate and liquid phase mass fractions, the chemical makeup and architecture of the constituents, interactions between the liquid and particulate phases, and the dispersed particle morphology. This study investigated the effect of particle shapes and sizes on shear thickening behavior. The particles of interest were hydrophilic fumed silica, multi-walled carbon nanotubes (MWCNTs), and oxidized graphene nanoplatelets (GONPs). The continuous liquid phase was polyethylene glycol with a molecular weight of 200 g/mol. All STFs had 0.15 mass fraction (MF) of fumed silica and an additional MF of one of the other carbon-based dispersed phases. Steady shear rheological tests were performed on the other STFs at 10 °C, 20 °C, and 30 °C. Varying shear thinning and shear thickening responses were observed as a function of shear rate. These phenomena were discussed in terms of how different particle-related factors impact these fluids’ behaviors.