Plate gap effect on vicosity and rheological model of shear thickening fluid

The present work investigates the effect of plate gap on the rheological properties of shear thickening fluid (STF) and proposes a phenomenological model to predict the viscosity curve of STF for different values of plate gap and temperature. Multiwalled carbon nanotube (MWCNT) reinforced silica-based STF (MWCNT/SiO₂-STF) containing 0.8 wt% MWCNT and 20 wt% SiO₂ nanoparticles was prepared using polyethylene glycol as a dispersion medium and tested for its steady and dynamic rheological behavior at different plate gaps. The peak viscosity of MWCNT/SiO₂-STF follows the characteristic behavior of an initial increase followed by a subsequent decrease corresponding to the increase in plate gap. A maximum viscosity of 198.89 Pa s was recorded at a plate gap of 1.0 mm. Although significant shear thinning in the dynamic rheological response of MWCNT/SiO₂-STF was noticed at a 1.0 mm gap, the storage and loss modulus were better than those at 0.5 mm gap. The proposed model based predicts the shear thinning and thickening behavior of STF at low and high shear rates for different values of plate gap with reasonable accuracy. The model also provides a very good fit for the viscosity of STF at different temperatures. Thus, the proposed model is suitable for numerical simulations as well as theoretical analysis in the vibration control field.