Rheology of Fumed Silica and Polyethylene Glycol Shear Thickening Suspension with Nanoclay as an Additive
Shear thickening properties of fumed silica-polyethylene glycol (PEG) with shear thickening fluid (STF) of different concentrations and with an organically modified clay, Nanomer I.28 E as nano-additive have been investigated by both steady-state and dynamic state rheology. Difference in rheology if instead of nanoclay, an equal wt% of additional fumed silica is added to 20 per cent fumed silica-PEG200 STF, has been studied. At 25 °C, in case of addition of nanoclay the increase in critical viscosity is less than that observed for same additional amount of fumed silica. Interestingly, an opposite result is seen at higher temperatures i.e. 45 °C and 55 °C. Moreover, the difference in steady-state and dynamic state viscosity values decreases on addition of nanoclay. It is noted that an increase in concentration of clay increases the value of dynamic parameters whereas for STF of only fumed silica particles the values are constant irrespective of the change in concentration. More importantly, ease of processing, elasticity, stability and consistency of rheological results of STF increases to a significant extent on addition of relatively inexpensive nano-additive.
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