The effects of nanocellulose addition, medium types and nano-silica concentrations on the flow behaviors of Nano silica-based shear thickening fluids

The shear thickening fluid (STF) is a non-Newtonian fluid that transitions from shear thinning to shear thickening, resembling solid-like behavior when subjected to a critical shear rate. This research focused on developing nano silica-based-shear thickening fluid (STF) and investigating the effects of silica content, media, and the addition of nanocellulose (NC) on its rheological behavior. The optimum formulation of STFs with low critical shear rate and high viscosity was determined using a parallel plate rheometer. The results showed that the fluid prepared from nano silica in PEG with a molar mass of 200 (PEG200) with the addition of nano-silica at least 25%wt showed the shear thickening behavior. As the amount of nano-silica increased from 25% wt to 40% wt, the peak viscosity enhanced from 10.7 Pa·s to 333.3 Pa·s, and the critical shear rate decreased from 316.3 1/s to 31.6 1/s. The critical shear rate was reduced when using PEG with higher molar mass (PEG400) as media instead of PEG200, but it increased when using glycerol. The addition of NC in STFs could enhance the sensitivity of STFs to the applied loads. The critical shear rate of the NC-modified STF was lower than that of unmodified STFs. This result could be explained by the H-bonding interaction of NC and silica, which led to the readily silica hydrocluster, that reduced the critical shear rate