Electrorheological behavior of low filled suspensions of highly anisometric montmorillonite particles

Abstract

The electrorheological (ER) behavior of modified montmorillonite (MMT) suspensions in polydimethylsiloxane is studied. As established by rotational viscometry, the samples with a dispersed phase concentration from 1 to 8 wt % reveal viscous Newtonian behavior and dramatically change their properties to elastic when electric field is applied. The rheological characteristics of the suspensions over 0–7 kV mm−1 range of electric field strengths are also studied. Novel X‐ray diffraction method is developed to evaluate the suspension of the filler in a siloxane medium and to calculate the degree of its exfoliation. The dependence of exfoliation degree, dielectric, and ER characteristics on the type of modifier in the MMT structure is considered. Based on the obtained data, a new model of system behavior with the various types of fillers is proposed and the prospects of utilizing MMT as a filler for ER fluids are demonstrated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47678.

Electrorheological Characteristics of Poly(diphenylamine)/magnetite Composite-Based Suspension

“…Figure 4 shows both shear stress (Figure 4a) and viscosity (Figure 4b) as a function of shear rate with an input electric field (0–2.0 kV/mm). Without an electric field, the shear stress presented an approximately linear relationship with the shear rate, indicating a similar trend to that of a Newtonian fluid [48]. On the other hand, under an electrical field, the shear stress increased significantly and showed a plateau region in a low shear rate range, which is consistent with Bingham fluid characteristics [5,49].…”

Halloysite nanotubes: Prospects in electrorheology

“…It is also interesting to note that the obtained values of moduli exceed almost twice the values obtained for systems filled with various montmorillonites. For organomodified montmorillonites the storage modulus value does not exceed 10 kPa at 7 kV/mm [26].…”

“…Thus, water has a weak influence on the electrorheological effect. Values of yield stress for halloysite are lower than for organomodified montmorillonites, for example, the 8 wt% pristine halloysite suspension reveals yield stress of 51 Pa at 7 kV/mm, meantime for Cloisite 30B and Nanofil SE 3010 yield stress is 90 and 57 Pa at the same conditions, respectively [26]. Such difference may be explained by formation of more strong chain-like structures from interacted plates rather than tubes, due to larger overlapping area in former case.…”

“…The percolation network becomes stronger with filler concentration and the yield stress value increases (see inset Figure 3a). It is important to note that the yield stress does not appear in montmorillonite suspensions up to 8 wt% [26]. A possible explanation of such behavior is a better dispersion of halloysite clay tubes in a polydimethylsiloxane medium compared to montmorillonite plates that tend to form tactoids.…”

“…Comparing the dielectric properties of halloysite with various modified montmorillonites, aluminosilicates with another layered morphology [25][26][27], it can be seen that the dielectric constant value of halloysite is only by order of magnitude lower than for the sodium form of montmorillonite (ε' = 8.09•10 5 ) and the conductivity is lower in more than 50 times (σ' = 6.10•10 -7 S/cm), respectively. As we show below, such difference open the opportunity to use halloysite as filler for ERFs at higher electric field compared to the sodium form of montmorillonite [26]. Flow and viscosity curves at various concentrations for samples filled with pristine and dried halloysite were measured.…”