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Open AccessArticle

Dynamic Behavior of Dilute Bentonite Suspensions under Different Chemical Conditions Studied via Magnetic Resonance Imaging Velocimetry

1
GeoRessources Laboratory, Université de Lorraine, UMR7359, BP10162 Vandoeuvre-lés-Nancy, France
2
LEMTA, CNRS, Université de Lorraine, UMR 7563, F-54500 Vandoeuvre-lés-Nancy, France
*
Author to whom correspondence should be addressed.
Colloids Interfaces 2018, 2(4), 41; https://doi.org/10.3390/colloids2040041
Received: 16 August 2018 / Revised: 21 September 2018 / Accepted: 25 September 2018 / Published: 27 September 2018
This study investigates dilute aqueous suspensions of bentonite particles using magnetic resonance imaging (MRI) velocimetry. Four different chemical conditions are tested to investigate the influence of pH and type of monovalent electrolyte on the local rheological behavior of bentonite suspensions. The results indicate the shear banding in a dilute suspension of 0.1 vol.% solid due to the formation of a continuous three-dimensional particle network under a certain chemical environment (i.e., pH 4 in 1 × 10−2 M KNO3). This network is responsible for the existence of the yield stress in that dilute suspension. Structural changes induced by modification of suspensions’ chemistry are examined via scanning electron microscopy. A previously established method based on processing the torques acquired via conventional rheometric measurement is also applied as an alternative way to recover local flow information. Within the shear rate range covered by our MRI velocimetry, the results of both methods show good agreement. This study suggests that the existence of a master curve (or global flow curve) for dilute suspensions is dependent on the bentonite particle organization, which is influenced by the suspension chemistry and the previous flow history. View Full-Text
Keywords: local rheology; shear banding; shear localization; monovalent salts; pH local rheology; shear banding; shear localization; monovalent salts; pH
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Chernoburova, O.; Jenny, M.; Kiesgen De Richter, S.; Ferrari, M.; Otsuki, A. Dynamic Behavior of Dilute Bentonite Suspensions under Different Chemical Conditions Studied via Magnetic Resonance Imaging Velocimetry. Colloids Interfaces 2018, 2, 41.

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