Halloysite nanotubes: Prospects in electrorheology

Abstract

Electrorheological fluids based on polydimethylsiloxane filled with halloysite nanotubes were studied. The filler structure was characterized by TEM, SEM, and X-ray diffraction. When an electric field is applied to suspensions, their rheological behavior changes-the contribution of the elastic component becomes significant and samples behave like a solid body. The effect of the electric field and filler concentration on the electrorheological behavior was investigated. The influence of water content on the filler structure, as well as on electrorheological and electrophysical properties of suspensions, was considered. Electrorheological fluids filled by halloysite with small water content exhibit slightly higher rheological characteristics under an electric field than dried ones. This study shows the prospects of using halloysite nanotubes as a dispersed phase for electrorheological fluids.

Influence of the Nanoclay Concentration and Oil Viscosity on the Rheological and Tribological Properties of Nanoclay-Based Ecolubricants

“…As it was previously pointed out by Martín-Alfonso et al, the values of the flow index of gel-like dispersions based on sepiolite and castor oil were quite close to zero [33]. This is a typical viscous flow behavior that characterizes fiber-like nanoclays due to their capacity to form percolated networks, as reported in Kuznetsov et al [34]. In fact, all samples prepared with the natural fiber-like sepiolite (Pangel B20) within the whole concentration range studied behaved as semisolid fluids at very low shear rates, similar to the yielding flow behavior observed for traditional lubricating greases [35], showing a shear-thinning response in the low and moderate shear rate region.…”

Preliminary Insights into Electro-Sensitive Ecolubricants: A Comparative Analysis Based on Nanocelluloses and Nanosilicates in Castor Oil

“…Due to their much lower ER potential, their yield stress dependence with the electric field showed a maximum yield stress value (or a limiting behavior). Kuznetsov et al [30] reported a similar evolution for concentrations of the "as received" halloysite of 1 and 2 wt.% in silicone oil suspensions, but not at higher concentrations. However, the dielectric behavior they found was different as compared to that in Figure 2.…”

“…The yield stress values were much lower than in the Cloisite 15A layered nanosilicate, at comparable concentrations and electric fields. Kuznetsov et al [30] explained such a difference by formation of more strong chain-like structures from interacted plates rather than tubes. A limiting yield stress value of ca.…”

“…On the contrary, Halloysite/paraffin wax blends did not show any anisotropy at all, probably because their different and irregular shapes did not enable ordered structures. Moreover, Kuznetsov et al, [30] reported that interacting plates yield more strong chain-like structures than interacting tubes, due to a larger overlapping area in the former case. Based on these comments and on the results shown in Figures 5 and 6, it might be that the minima that appear in the fiber-like (nanocelluloses) and rod-like (nanotubes) particles are a consequence of the breakup of weaker structures.…”

The orientation of the layered aluminosilicates particles with a high aspect ratio in paraffin under electric field

“…Ранее было показано, что суспензии монтмориллонита и галлуазита в полидиметилсилоксане низкой молекулярной массы проявляют электрореологиче-ДОКЛАДЫ АКАДЕМИИ НАУК, 2019, том 486, № 6, с. 663-667 ФИЗИКА ский эффект: значения предела текучести возрастают с ростом концентрации и напряжённости электрического поля [11,12]. При этом присутствие различных соединений на поверхности частиц, таких как неорганические ионы, органические модификаторы или вода, оказывает существенное влияние на диэлектрические характеристики наполнителя и, как следствие, на электрореологическое поведение [4,13].…”