Very Concentrated Plate-Like Kaolin Suspensions Under Large Amplitude Oscillatory Shear: a Microstructural Approach
Abstract
Kaolinite particles are plate-like natural clay particles. The behavior of very concentrated kaolinite suspensions {0> 0,4) atpH 7 is governed by both repulsive electrostatic interactions between negatively charged basal planes and excluded volume interactions [1]. The complex rheological behavior of kaolinite suspensions is closely related to the suspension microstructure at rest, resulting from inter-particle interactions, and its deformation under stress. Very concentrated kaolinite suspensions undergoing large amplitude oscillatory shear (LAOS) are known to exhibit a peculiar nonlinear viscoelastic behavior, characterized by a hump in G" modulus, whose microscopic origin is still a matter of debate. In this work, a microstructural interpretation of this nonlinear behavior is proposed. For this purpose, the viscoelastic behavior of suspensions has been investigated as a function of volume fraction, ionic strength and in the presence of polymer at various concentrations, in order to monitor the influence of both the nature and the intensity of interparticle interactions.