Eur. Phys. J. E 6, 245-253 (2001)
Universal properties of lamellar systems under weak shear
C. Meyer, S. Asnacios and M. KlémanLaboratoire de Minéralogie-Cristallographie de Paris (UMR7590), T16 case 115, 4 place Jussieu, F-75252 Paris cédex 05, France maurice.kleman@mines.org
(Received 18 April 2001 and Received in final form 25 October 2001)
Abstract
We have observed that different lamellar phases
(thermotropic, lyotropic of surfactants or blockcopolymers) share
the same rheological properties
,
m
=
, independently of their chemical nature, in a
range of shear rates
, shear stresses 
, and
temperatures T, where the flow is stationary. It is argued that
the key phenomenon is the appearance of screw dislocations whose
glide under an applied shear counterbalances plastically the
applied vorticity, and stabilizes the layers, whose slip past each
other is thus made more feasible. The theory, which makes use in
other respects of the high-temperature creep model in solids,
reproduces correctly the power law behavior and the values of
A(T).
61.30.Cz - Molecular and microscopic models and theories of liquid crystal structure.
83.85.Cg - Rheological measurements - rheometry.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001
