2017 Impact factor 1.802
Soft Matter and Biological Physics

Eur. Phys. J. E 2, 343-350

Shear-thickening transition in surfactant solutions: New experimental features from rheology and flow birefringence

J.-F. Berret1 - R. Gamez-Corrales1 - S. Lerouge2 - J.-P. Decruppe2

1 Unité Mixte de Recherche CNRS/Université de Montpellier II n$^{\circ}$ 5581, Groupe de Dynamique des Phases Condensées, F-34095 Montpellier Cedex 05, France
2 Groupe de Rhéophysique des Colloides, Université de Metz, 57078 Metz - France
berret@gdpc.univ-montp2.fr

Received 11 November 1999

Abstract
We report on the shear-thickening transition observed in dilute aqueous solutions of cetyltrimethylammonium tosylate ( \ensuremath{\mathsf{CTAT}}) at concentrations $\phi\sim 0.2\%$. We have re-examined the kinetics of the shear-thickening transition using start-up experiments at rates above the critical shear rate $\dot{\gamma}_{c}$. Using simple well-defined protocols, we have found that the transient mechanical response depends dramatically on the thermal and on the shear histories. Using the same protocols, flow birefringence experiments were carried out. The gap of a Couette cell containing the sheared solution has been visualized between crossed polarizers in steady shear conditions, as well as in start-up experiments. We show that the birefringent shear-induced phase starts from the inner cylinder and grows along the velocity gradient direction, as in a shear banding situation. However, around $\dot{\gamma}_{c}$ we have not observed a regime of phase coexistence (isotropic and birefringent).

PACS
83.50.By Transient deformation and flow; time-dependent properties: start-up, stress relaxation, creep, recovery, etc. - 83.50.Qm Thixotropy; thickening flows - 83.85.Ei Optical methods; sonography

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