Asymmetrical polarization of spherical colloidal particle double layer in electrical fields

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It has long been accepted that the drastic increase in the viscosity of electrorheological fluids subjected to electric fields is due to interactions between the induced dipole moments of the colloidal particles in the suspensions. Computer simulations of dipole-dipole interactions have produced chain and column formations of particles in the direction of the applied field that agree well with experimental observations. In an aqueous suspension of colloidal particles, however, the polarization of particles is very sensitive to the frequency of the applied electric field, and the dynamics of the particles can differ drastically from the dynamics that would be expected ... continued below

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9 p.

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Hu, Y.; Kumar, V. & Fraden, S. April 1, 1995.

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This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 115 times , with 4 in the last month . More information about this article can be viewed below.

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  • Hu, Y.
  • Kumar, V. Wellesley College, MA (United States). Physics Dept.
  • Fraden, S. Brandeis Univ., Waltham, MA (United States). Physics Dept.

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Description

It has long been accepted that the drastic increase in the viscosity of electrorheological fluids subjected to electric fields is due to interactions between the induced dipole moments of the colloidal particles in the suspensions. Computer simulations of dipole-dipole interactions have produced chain and column formations of particles in the direction of the applied field that agree well with experimental observations. In an aqueous suspension of colloidal particles, however, the polarization of particles is very sensitive to the frequency of the applied electric field, and the dynamics of the particles can differ drastically from the dynamics that would be expected from a simple induced dipole model. In certain frequency regimes, instead of forming chains and columns in the direction of a linear applied field, the particles are dynamically unstable and circulate in bands that tilt at a significant angle relative to the direction of the field. This indicates that the interactions between the particles are no longer symmetrical with respect to the applied electric field. The authors have proposed a phenomenological model to explain the mechanism of this symmetry breaking. They have carried out a computer simulation of colloidal particle dynamics resulting from their model, and the results of the simulation agree well with experimental observations. When a particle is spinning, the diffusion of the ions in the double layer becomes asymmetrical with respect to the electric field, with the ions diffusing faster in the direction of spinning than against it. This causes the induced dipole moment of the particle to be misaligned with respect to the applied field. The authors earlier simulation results show that this misalignment between the polarization of the particle and the applied electric field plays a crucial role in the formation of a band of particles tilted at an angle relative to the direction of the applied electric field.

Physical Description

9 p.

Notes

OSTI as DE96000734

Medium: P; Size: 9 p.

Source

  • 208. American Chemical Society (ACS) national meeting, Washington, DC (United States), 21-26 Aug 1994

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  • Other: DE96000734
  • Report No.: DOE/ER/45522--3
  • Report No.: CONF-940813--42
  • Grant Number: FG02-94ER45522
  • Office of Scientific & Technical Information Report Number: 110682
  • Archival Resource Key: ark:/67531/metadc623911

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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Creation Date

  • April 1, 1995

Added to The UNT Digital Library

  • June 16, 2015, 7:43 a.m.

Description Last Updated

  • April 13, 2017, 2:54 p.m.

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Hu, Y.; Kumar, V. & Fraden, S. Asymmetrical polarization of spherical colloidal particle double layer in electrical fields, article, April 1, 1995; United States. (digital.library.unt.edu/ark:/67531/metadc623911/: accessed September 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.