Organisation des matériaux en suspension

Organization of clay suspensions

This unit will present the different possible structures of colloidal systems (in water saturated conditions) and will try to make the link with rheological properties. Concepts concerning electrostatic interactions (type, condition and range), auto-organization and phase transitions will be introduced in general and illustrated in the cases of clayey dispersions. The structural and mechanical behavior will be analyzed by using tools as small-angle X-ray scattering and rheology in saturated conditions. The analysis of data will familiarize students with experimental approaches, especially on the type of information which can be obtained. 

The main objective of this unit will be to give basics of physico-chemistry and tools in order to determine/predict the structure of colloidal dispersions in relation with the physico-chemical parameters of the media (salinity, solid/solution ratio…) and intrinsic properties of the fine particles chosen (size, morphology, surface charge…). The different concepts will be illustrated by giving examples issued from everyday life and scientific literature.

Prerequisites

Knowledge of:

• Electrical double layer

• Mechanical properties and rheological models

Content

•Colloidal stability (DLVO theory, repulsive and attractive forces)

•Structural organization of repulsive colloidal systems in water saturated conditions (using data from small-angle X-ray scattering)

•Liquid crystal - phase transition

•Relation between structure of colloidal system and rheological properties

• Prédire le comportement colloïdal d’une suspension (stabilité versus agrégation)
• Savoir commenter un diagramme de phase salinité/rapport solide-solution pour un système colloïdal
• Connaitre les paramètres de structure d’un système colloïdal pouvant être obtenus par analyse de données de diffusion aux petits angles
• Faire le lien multi-échelles entre propriétés mécaniques (macroscopique) et l’organisation colloïdale (méso et microscopique)

Israelachvili, J. N. Intermolecular and Surface Forces; Academic press, 2015.

Lekkerkerker, H. N. W.; Tuinier, R. Colloids and the Depletion Interaction, Eds. Springer, 2011