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
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
(
)
at concentrations
.
We have
re-examined the kinetics of the shear-thickening transition using
start-up experiments at rates above the critical shear rate
.
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
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
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
