Shear-induced micellar growth in dilute surfactant solutions
Unité Mixte de Recherche CNRS/Université de
Montpellier II No. 5581 Groupe de
Dynamique des Phases Condensées - F-34095
Montpellier Cedex 05, France
2 Institut Laue-Langevin - BP 156, F-38042 Grenoble cedex 9, France
Corresponding author: email@example.com.
Accepted: 29 March 2001
The shear-thickening transition observed in aqueous solutions of cetyltrimethylammonium tosylate (CTAT) is investigated using rheology and small-angle neutron scattering under shear. Above a critical shear rate , the increase of the apparent shear viscosity is due to the formation of a shear-induced phase. Using a Porod representation to analyze the aggregate local morphology, we demonstrate that the shear-induced viscous state consists of cylindrical micelles strongly aligned in the flow. We also investigate the shear rate and surfactant concentration dependencies of the structure factor peak revealed at low wave vectors. Above , the systematic shift of the structure factor peak to lower wave vectors is interpreted in terms of the shear-induced micellar growth of the aggregates.
PACS: 47.50.+d – Non-Newtonian fluid flows / 83.60.Rs – Shear rate-dependent structure (shear thinning and shear thickening) / 83.85.Hf – X-ray and neutron scattering
© EDP Sciences, 2001