title: Dielectric spectroscopy of concentrated colloidal suspensions.
abstract: A comparison between experimental measurements and theoretical calculations of the permittivity and conductivity of concentrated colloidal suspensions is presented. Dielectric spectroscopy measurements for 100nm and 200nm diameter polystyrene spheres at volume fractions between ϕ=0.01-0.18 and electrolyte concentrations 0.01-1mM KCl (P.J. Beltramo, E.M. Furst, Langmuir 28 (2012) 10703-10712) are compared to cell-model calculations that account for the hydrodynamic and electrokinetic interactions between particles (F. Carrique, F.J. Arroyo, M.L. Jimenez, A.V. Delgado, J. Chem. Phys. 118 (2003) 1945-1956). Under most conditions, there is good agreement between experiment and theory. At low ionic strengths, the dielectric increment exhibits a low-frequency plateau in the experimental spectroscopy and cell model calculations. However, at the highest ionic strengths, the cell model predicts a low frequency plateau that is not observed experimentally. The conductivity increments qualitatively agree over all volume fractions, ionic strengths and frequencies.
authors: Department of Chemical and Biomolecular Engineering, Center for Molecular and Engineering Thermodynamics, University of Delaware, 150 Academy St., Newark, DE 19716, USA.
authors: Peter J
authors: PJ
authors: Beltramo
authors: Rafael
authors: R
authors: Roa
authors: Félix
authors: F
authors: Carrique
authors: Eric M
authors: EM
authors: Furst
keywords: Cell model; Concentrated suspensions; Dielectric spectroscopy; Electrokinetics