Abstract
In this report, we have investigated aqueous smectite clay suspensions (montmorillonite or laponite), containing a low molecular weight sodium polyacrylate. Actually, this polyelectrolyte serves as a dispersing agent in drilling fluids based on smectite and water. In order to describe these clay suspensions, we have employed different characterization methods: small angle X-ray scattering (SAXS) using a Holmes and a Bonse-Hart apparatus, osmotic pressure measurements and NMR relaxation. We have shown that the model presented in the literature to convert proton relaxation measurements, in term of external surface area of clay particles available to water, was not adapted. The SAXS results indicate otherwise, that sodium smectite clay suspensions were mainly composed of elementary clay sheets, whose organisation leads to a two phase system. Aggregation of the clay platelets occurs when divalent cations act as clay counterions, but also under an increase of the medium ionic strength. We have proposed schematic illustrations to describe in each cases the structure of the system. When added to a sodium montmorillonite suspension, the sodium polyacrylate gives rise to a strong orientation of the clay sheets. Our results indicate that this organisation must be attributed to an osmotic effect of the polyelectrolyte expelled from the interlayer
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Citation Formats
Morvan, M.
Macrostructure of smectite - water systems: influence of anionic polyelectrolytes upon organization of montmorillonite suspensions; Macrostructure des systemes smectites-eau. Influence de polyelectrolytes anioniques sur l`organisation de suspensions de montmorillonite.
France: N. p.,
1993.
Web.
Morvan, M.
Macrostructure of smectite - water systems: influence of anionic polyelectrolytes upon organization of montmorillonite suspensions; Macrostructure des systemes smectites-eau. Influence de polyelectrolytes anioniques sur l`organisation de suspensions de montmorillonite.
France.
Morvan, M.
1993.
"Macrostructure of smectite - water systems: influence of anionic polyelectrolytes upon organization of montmorillonite suspensions; Macrostructure des systemes smectites-eau. Influence de polyelectrolytes anioniques sur l`organisation de suspensions de montmorillonite."
France.
@misc{etde_10112419,
title = {Macrostructure of smectite - water systems: influence of anionic polyelectrolytes upon organization of montmorillonite suspensions; Macrostructure des systemes smectites-eau. Influence de polyelectrolytes anioniques sur l`organisation de suspensions de montmorillonite}
author = {Morvan, M}
abstractNote = {In this report, we have investigated aqueous smectite clay suspensions (montmorillonite or laponite), containing a low molecular weight sodium polyacrylate. Actually, this polyelectrolyte serves as a dispersing agent in drilling fluids based on smectite and water. In order to describe these clay suspensions, we have employed different characterization methods: small angle X-ray scattering (SAXS) using a Holmes and a Bonse-Hart apparatus, osmotic pressure measurements and NMR relaxation. We have shown that the model presented in the literature to convert proton relaxation measurements, in term of external surface area of clay particles available to water, was not adapted. The SAXS results indicate otherwise, that sodium smectite clay suspensions were mainly composed of elementary clay sheets, whose organisation leads to a two phase system. Aggregation of the clay platelets occurs when divalent cations act as clay counterions, but also under an increase of the medium ionic strength. We have proposed schematic illustrations to describe in each cases the structure of the system. When added to a sodium montmorillonite suspension, the sodium polyacrylate gives rise to a strong orientation of the clay sheets. Our results indicate that this organisation must be attributed to an osmotic effect of the polyelectrolyte expelled from the interlayer space. Then, we have shown that the dispersing effect of the polyelectrolyte on calcium montmorillonite suspensions, was due to an ion exchange of the calcium clay counterions by the sodium provided by the polyelectrolyte. (author).}
place = {France}
year = {1993}
month = {May}
}
title = {Macrostructure of smectite - water systems: influence of anionic polyelectrolytes upon organization of montmorillonite suspensions; Macrostructure des systemes smectites-eau. Influence de polyelectrolytes anioniques sur l`organisation de suspensions de montmorillonite}
author = {Morvan, M}
abstractNote = {In this report, we have investigated aqueous smectite clay suspensions (montmorillonite or laponite), containing a low molecular weight sodium polyacrylate. Actually, this polyelectrolyte serves as a dispersing agent in drilling fluids based on smectite and water. In order to describe these clay suspensions, we have employed different characterization methods: small angle X-ray scattering (SAXS) using a Holmes and a Bonse-Hart apparatus, osmotic pressure measurements and NMR relaxation. We have shown that the model presented in the literature to convert proton relaxation measurements, in term of external surface area of clay particles available to water, was not adapted. The SAXS results indicate otherwise, that sodium smectite clay suspensions were mainly composed of elementary clay sheets, whose organisation leads to a two phase system. Aggregation of the clay platelets occurs when divalent cations act as clay counterions, but also under an increase of the medium ionic strength. We have proposed schematic illustrations to describe in each cases the structure of the system. When added to a sodium montmorillonite suspension, the sodium polyacrylate gives rise to a strong orientation of the clay sheets. Our results indicate that this organisation must be attributed to an osmotic effect of the polyelectrolyte expelled from the interlayer space. Then, we have shown that the dispersing effect of the polyelectrolyte on calcium montmorillonite suspensions, was due to an ion exchange of the calcium clay counterions by the sodium provided by the polyelectrolyte. (author).}
place = {France}
year = {1993}
month = {May}
}