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Rhéologie des suspensions aqueuses de noir de carbone et de fluides à seuil modèles dans leur régime solide

Abstract : In REDOX flow batteries, liquid electrolytes are used to convert chemical energy into electrical energy and vice versa for energy storage. However, the storage capacities of this type of battery depend on the concentration of the REDOX elements, in turn influenced by the element solubility, which is generally low. Our work is part of the ANR V-S-L project, which aims to improve the storage capacities of vanadium REDOX flow batteries using liquid electrolytes charged with solid vanadium salt. In addition, to achieve a more conductive electrolyte, highly conductive carbon black nanoparticles are added. Under these conditions, the electrolyte is no longer a dilute solution flowing easily as a simple fluid (water, honey, etc.) but a yield stress fluid whose behavior is essentially driven by the colloidal interactions between carbon black particles. Our objective is therefore to understand and describe the rheological behavior of aqueous carbon black suspensions loaded with vanadium salt, replaced in our study by glass beads. We first studied the carbon black suspensions alone. Standard rheometry experiments and local rheometry experiments under MRI (Magnetic Resonance Imaging) allowed us to precisely characterize the liquid regime and the solid-liquid transition of these suspensions. The study of their solid regime showed us the need to further the properties of yield stress fluids in general in their solid regime. For this, we have put in place original methods and procedures (superimpositions of oscillation on creeps, creeps then recoveries) which we first applied to several model yield stress fluids. Thus, we observed a generic elastoplastic behavior in the solid regime for which we proposed a single parameter model making it possible to describe the strains as a function of the stress. We then applied to carbon black suspensions the same procedures, which revealed a singular behavior of stiffening under deformation in their solid regime. Finally, the study of the glass beads mixture in the carbon black suspensions permitted to observe rather an early divergence in the yield stress and the elastic modulus with glass bead concentration, unlike the grain dispersions in the model yield stress fluids. By the way, we specified the flow behavior of two polysaccharides with unique rheological behavior for macromolecules: gum Arabic used to disperse hydrophobic carbon black in water and xanthan gum
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Submitted on : Wednesday, April 28, 2021 - 4:03:08 PM
Last modification on : Thursday, April 29, 2021 - 3:35:49 AM


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  • HAL Id : tel-03211308, version 1



Elie N'Gouamba. Rhéologie des suspensions aqueuses de noir de carbone et de fluides à seuil modèles dans leur régime solide. Science des matériaux [cond-mat.mtrl-sci]. Université Paris-Est, 2020. Français. ⟨NNT : 2020PESC1042⟩. ⟨tel-03211308⟩



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