Electrorheological effects in suspensions of hydrophobically modified saponite

Dürrschmidt, T.; Hoffmann, H.

doi:10.1016/s0927-7757(99)00078-3

Cited by 26 publications

(16 citation statements)

References 26 publications

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“…The yield stress of such an ER material can easily reach 10 kPa at 2.5 kV/mm and a particle loading of 45 wt.-%. Aluminosilicates encompass a family of zeolite materials of metal cation or a mixture of metal cations of average valence charge n; x, y, and w are integers), including clay (saponite or montmorillonite); [43] zeolite 3A, 5A, and X-type; [44,45] and various molecular sieves. [46±48] Plenty of these materials are commercially available and can be modified in various aspects with regard to the crystal structure, cation composition, and particle size and shape, etc., and constitute a large number of ER fluids.…”

Section: Aluminosilicatesmentioning

confidence: 99%

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Electrorheological Fluids

2001

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Materials that switch from liquid‐like to solid‐like upon application of an electric field are termed electrorheological fluids. The general features and preparation of these smart materials are reviewed before recent advances in the improvement and applications (e.g., sensors, damping devices, inks) of these fluids are described. Materials ranging from aluminosilicate (see Figure) and carbonaceous inorganic materials to liquid‐crystal polymers to semiconductive polymers can be used to fabricate electrorheological fluids.

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Section: Aluminosilicatesmentioning

confidence: 99%

“…Another shortcoming is particle sedimentation, which can be partially overcome using suitable surfactants. [43] Aluminosilicate particles are hard, and abrasive to the ER device.…”

Section: Aluminosilicatesmentioning

confidence: 99%

Electrorheological Fluids

2001

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“…Several models have been proposed to explain the ER effect: (1) distortion and overlap of the electric double layers of dispersed particles, (2) formation of bridges between the particles, (3) inter-electrode circulation of the particles, (4) the electrostatic polarization (particle polarization in an electric field) model which can explain many of the experimental results [14,15]. According to the electrostatic polarization model, magnitude of the ER effect depends on the dielectric mismatch between the dispersed and continuous phases in the suspension [18].…”

Section: Introductionmentioning

confidence: 99%

An investigation of electrorheological properties of calcium carbonate suspensions in silicone oil

2005

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In this study, electrorheological behavior of suspensions prepared from 0.9 and 5.0 µ m calcium carbonate particulates, dispersed in insulating silicone oil medium was investigated. Sedimentation stabilities of suspensions ( c = 5 wt %) prepared using these calcium carbonate powders were determined to be 6 and 4 days, respectively. Electrorheological activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. Shear stress of calcium carbonate suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions was decreased sharply with increasing shear rate and particle size, showing a typical shear thinning non-Newtonian visco-elastic behavior. Effects of elevated temperature and polar promoter onto electrorheological activity of calcium carbonate/silicone oil system were also investigated.#

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“…The mechanism is not fully understood yet, but it is mainly triggered by the so-called interfacial polarization, and requires electric anisotropy of the particles [9]. Consequently, particle shape [10] and surface properties [11] can also be critically important, as dielectric properties largely depend on them.…”

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confidence: 99%

Intercalation-enhanced electric polarization and chain formation of nano-layered particles

et al. 2006

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ray scattering (including small-angle scattering). PACS. 82.70.Dd -Colloids. PACS. 83.80.Gv -Electro-and magnetorheological fluids.Abstract. -Microscopy observations show that suspensions of synthetic and natural nanolayered smectite clay particles submitted to a strong external electric field undergo a fast and extended structuring. This structuring results from the interaction between induced electric dipoles, and is only possible for particles with suitable polarization properties. Smectite clay colloids are observed to be particularly suitable, in contrast to similar suspensions of a nonswelling clay. Synchrotron X-ray scattering experiments provide the orientation distributions for the particles. These distributions are understood in terms of competing (i) homogenizing entropy and (ii) interaction between the particles and the local electric field; they show that clay particles polarize along their silica sheet. Furthermore, a change in the platelet separation inside nano-layered particles occurs under application of the electric field, indicating that intercalated ions and water molecules play a role in their electric polarization. The resulting induced dipole is structurally attached to the particle, and this causes particles to reorient and interact, resulting in the observed macroscopic structuring. The macroscopic properties of these electrorheological smectite suspensions may be tuned by controlling the nature and quantity of the intercalated species, at the nanoscale.In this letter we study colloidal suspensions of electrically-polarizable particles in nonconducting fluids. When such suspensions are subjected to an external electric field, usually of the order of 1kV/mm, the particles become polarized, and subsequent dipolar interactions are responsible for aggregating a series of interlinked particles that form chains and columns parallel to the applied field. This structuring occurs within seconds, and disappears almost instantly when the field is removed [1][2][3][4][5]. It coincides with a drastic change in rheological properties (viscosity, yield stress, shear modulus, etc.) of the suspensions [6], which is why they are sometimes called electrorheological fluids (ERFs). This makes the mechanical behavior readily controllable by using an external electric field [1][2][3][4][5][6][7]. Particle size has a quite diverse impact on the behavior of ERFs [8]. The nature of the insulating fluid and of the colloidal particles determines the electrorheological behavior of the suspensions. The mechanism is not fully understood yet, but it is mainly triggered by the so-called interfacial polarization, EDP Sciences

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Electrorheological effects in suspensions of hydrophobically modified saponite

Cited by 26 publications

References 26 publications

Electrorheological Fluids

Electrorheological Fluids

An investigation of electrorheological properties of calcium carbonate suspensions in silicone oil

Intercalation-enhanced electric polarization and chain formation of nano-layered particles

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