Shear-induced orientations in a lyotropic defective lamellar phase
Albert-Ludwigs-Universität Freiburg i. Br., Institut für Makromolekulare Chemie, Stefan-Meier-Straße 31, D-79104 Freiburg, Germany
2 Institut Laue-Langevin, BP 156 - F-38042 Grenoble, France
Accepted: 22 July 1998
The influence of shear on a defective lamellar phase of the ternary mixture sodium dodecyl sulphate/decanol/ was studied using small-angle neutron scattering (SANS), small-angle light scattering (SALS) and birefringence. Shear flow leads to an alignment of lamellae but in addition to previous studies, we found a reorientation from "perpendicular” lamellae, i.e. with the layer normal along the vorticity direction, to "parallel” lamellae with the layer normal along the velocity gradient direction at increasing shear rates. The reorientation processes were accompanied by a decrease of viscosity.
PACS: 61.30.Eb – Experimental determinations of smectic, nematic, cholesteric, and other structures / 83.20.Hn – Structural and phase changes / 83.50.-v – Deformation; material flow
© EDP Sciences, 1998