J. Phys. IV France 123 (2005) 341-344
Rheological behaviour of the condensed suspension of fluorinated montmorillonite "rassoul" particles in aqueous mediumA. Khaldoun1, F. González-Caballero2, J.G. López-Durán2, N. Mahrach3 and M.L. Kerkeb3
1 Van der Waals-Zeeman Institute, University of Amsterdam Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands
2 Department of Applied Physics, Faculty of Sciences, University of Granada, 18071 Granada, Spain
3 Department of Physics, Faculty of Sciences, Abdelmalek Essaadi University, 93000 Tetouan, Morocco
In this article, we describe the rheology of a condensed suspension of FNaMt particles 5w% as a function of pH, at constant ionic strength. The steady-state viscosimerty measurements showed that the yield stress increase up to an order of magnitude between pH3 and pH6, with a much slower rate of increase in the 6 to 9 pH interval. Concerning the dynamic (oscillatory) measurements, it is found that both the elastic G' and viscous G" are practically independent of frequency. It is also demonstrated that G'>G", the difference being larger at basic pH values. These results suggest the existence of an elastic, coagulated structure at pH acid, whereas as the pH is decreased such structure is more relaxed.
© EDP Sciences 2005