Study of a shear thickening fluid: the dispersions of silica nanoparticles in 1-butyl-3-methylimidazolium tetrafluoroborate

Abstract

The dispersions was prepared by dispersing hydrophilic silica nanoparticles with an average diameter of 50 nm in 1-butyl-methylimidazolium tetrafluoroborate ([C 4 mim][BF 4 ]), and investigated under the steady shear and oscillatory shear, respectively. Experimental results indicate that all of the dispersions present shear thinning, notable shear thickening, and shear thinning successively with increasing shear rate; the shear thickening behavior is derived from silica nanoparticle clusters and strongly controlled by silica nanoparticle content and temperature. The shear thickening fluid (STF) exhibits reversible property and transient response ability, and the time of transient response is no more than 100 ms. The conductivity of the STF is increased with increasing silica nanoparticle content, and the conductivity of 27 wt% dispersions is even two times as big as that of pure [C 4 mim] [BF 4 ]. The dispersions with high solid content dilate and present a phase transition changing from a liquid-like to a solid-like soft material in the shear thickening region. A theoretical model is developed to imitate the mechanism of shear thickening in the dispersions.

Investigation on rheological characteristics of magnetorheological shear thickening fluids mixed with micro CBN abrasive particles

“…When increased magnetic flux densities from 70 to 210 mT were employed, MRSTPFs behaved as a storage system. This was because the storage modulus got higher than the loss modulus under the 0.1-100 Hz shear frequency [57]. This behavior was consistent with the magnetorheological effect.…”

“…The storage modulus and loss modulus gradually increased at first when magnetic flux density was 0 mT. This was caused by the balanced status between the generated and the destroyed hydro-clusters [57]. After that, the storage modulus and loss modulus sharply decreased to the critical shear frequency.…”

Characterization of the rheological behaviors and mechanical properties of fabrics impregnated by different shear thickening fluids at changing temperatures

“…Solid fraction, which is the fraction of the total volume or weight occupied by particles against the whole system, is found to be the most important factor affecting shearthickening. Previous studies have confirmed that increasing particle fraction leads to a decrease in the critical shear rate, and the high fraction dispersion exhibits a greater increase in viscosity [9][10][11]. Moreover, the critical shear rate increases with the increasing particle size, and the maximum viscosity of the suspension increases when decreasing the size and dispersity of particles [12][13][14].…”

A review of fibrous materials for soft body armour applications

“…As shown in Fig. 12(d), Qin et al 116 hypothesised that in case of high solid content, shear thickening is dictated by jamming of particles akin to a logjam while at lower solid content, shear thickening is governed by hydrocluster formation. However, it was found later by Lin et al 134 that contact forces also dictate continuous shear thickening (CST) as well where the solid content can be as low as 49%.…”