Rheology and microstructure of dense suspensions of plate-shaped colloidal particles
- 1 July 1999
- journal article
- Published by Society of Rheology in Journal of Rheology
- Vol. 43 (4), 847-871
- https://doi.org/10.1122/1.551013
Abstract
The flow properties and microstructure of dense kaolin clay suspensions are explored for volume fractions, φ, as large as 0.39. To avoid flocculation these particles were suspended in p H 10 buffer solutions where edge–face interactions are negligible. These plate-shaped particles have an aspect ratio of 10–12 and, thus, are likely to show alignment above a critical volume fraction φ * > 0.10. At low φ, the suspensions are Newtonian but show substantial orientation with increased shear rate. As φ is increased, the suspensions develop a yielding type of behavior. In the concentrated region φ > φ * , elastic moduli are a function of the previously applied shear rate, γ̇, decreasing from a low shear rate plateau of G ′ (0) to a high shear rate plateau of G ′ (∞). We interpret the modulus behavior as being a consequence of changes in alignment of domains in the suspension. Conductivity and x-ray scatteringmeasurements confirm that particle alignment increases with increasing shear rate. The normalized modulus value, G norm ′ =[G ′ (γ̇)−G ′ (∞)]/[G ′ (0)−G ′ (∞)], is independent of φ indicating that the characteristic alignment shear rate is independent of volume fraction. Conductivities and x-ray scattering intensities normalized in the same manner are also independent of the volume fraction, and superimpose on the modulus data. Surprisingly, these data indicate that fractional particle alignment at a given shear rate is independent of φ for 0.05 < φ < 0.39.Keywords
This publication has 39 references indexed in Scilit:
- A diffraction technique to investigate the orientational alignment of anisotropic particles: studies of clay under flowEurophysics Letters, 1996
- Molecular orientation and instability in plane Poiseuille flow of a liquid-crystalline polymerJournal of Rheology, 1994
- Suspensions of prolate spheroids in Stokes flow. Part 2. Statistically homogeneous dispersionsJournal of Fluid Mechanics, 1993
- Suspensions of prolate spheroids in Stokes flow. Part 1. Dynamics of a finite number of particles in an unbounded fluidJournal of Fluid Mechanics, 1993
- Suspensions of prolate spheroids in Stokes flow. Part 3. Hydrodynamic transport properties of crystalline dispersionsJournal of Fluid Mechanics, 1993
- Colloidal properties of synthetic hectorite clay dispersionsJournal of Colloid and Interface Science, 1986
- Rheooptical Studies of Racemic Poly(γ-benzyl glutamate) Liquid CrystalsMacromolecules, 1980
- Use of electrical conductance measurements in studies of the orientation of microscopic particles in stationary and flowing suspensionsJournal of Applied Physics, 1973
- The kinetics of flowing dispersionsJournal of Colloid and Interface Science, 1967
- The kinetics of flowing dispersionsJournal of Colloid and Interface Science, 1967