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The rheological properties of dispersions of Laponite, a synthetic hectorite-like clay, in electrolyte solutions

Published online by Cambridge University Press:  09 July 2018

B. S. Neumann  and
K. G. Sansom
B. S. Neumann
Affiliation:
Laporte Industries Ltd., Organics and Pigments Division, Redhill, Surrey
K. G. Sansom
Affiliation:
Laporte Industries Ltd., Organics and Pigments Division, Redhill, Surrey
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Abstract

Dispersions of Laponite clay in various electrolyte solutions have been studied. In the total absence of electrolyte the synthetic clay forms a sol at 2% concentration. All cations cause gelling and flocculation.

It has been found that for any given clay concentration the yield value of the dispersions at equivalent flocculation level is the same for all electrolyte solutions, making it possible to study all types of dispersions at a standard level of flocculation.

At standard level of flocculation, the yield values have been found to follow exponential relationships with clay concentration with a break in the curves occurring at about 1·6% clay concentration. It is postulated that the break in the yield value curve occurs when enough clay is present to form a card-house structure. The plastic viscosities show a linear relationship with concentration and indicate high effective dispersed volume fractions at low clay concentrations.

When comparing the flocculating effects of different cations at fixed clay concentration, an empirical relationship has been found between cation concentration giving standard flocculation level, cation valency and radius.

Type
Research Article
Information
Clay Minerals , Volume 9 , Issue 2 , December 1971 , pp. 231 - 243
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1971

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