Shear thickening effect of the suspensions of silica nanoparticles in PEG with different particle size, concentration, and shear

In this study, a series of shear thickening fluids based on the suspension of silica nanoparticles in polyethylene glycol (PEG) were prepared, and the influences of particle size, concentration, and shear on the shear thickening effect were investigated by rheological measurements. It was observed that with the increase of silica concentration, the viscosity and critical shear rate of the fluid become higher, and the shear thickening phenomenon becomes more obvious. Under the same particle concentration, higher shear thickening effect and lower critical shear thickening concentration appear for smaller nanoparticles but for larger micro particles. As the temperature increases, the enhanced Brownian motion leads to the rising of critical shear rate and the strengthening of shear thickening effect. The rheological properties of these fluids are very sensitive to the shear rate with fast viscosity change for response, and smaller nanoparticles can recover their network structures more easily after shear breakage.