Eur. Phys. J. E 6, 139-145 (2001)

Undulating membrane structure under mixed extensional-shear flow

S.H.J. Idziak¹, S.E. Welch¹, M. Kisilak¹, C. Mugford¹, G. Potvin¹, L. Veldhuis¹ and E.B. Sirota<sup>2

1</sup>  Department of Physics and Guelph-Waterloo Physics Institute, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1
²  ExxonMobil Research and Engineering Company, Corporate Strategic Research, Route 22E Clinton Township, Annandale, NJ 08801-0998, USA

idziak@uwaterloo.ca

(Received 29 May 2001 and Received in final form 20 July 2001 )

Abstract
We report on studies using a new X-ray extensional flow cell to examine, for the first time, the structure of undulating lamellar lyotropic liquid crystal systems under extensional flow. The extensional component of the flow profile produced within this cell causes the lamellae to orient. We find that, although the intermembrane spacing does not change at low flow rates, it suddenly decreases after a critical flow rate has been attained due to the stretching and straightening of the lamellae. The effects of the shear component of flow on this oriented system have been examined in the context of a theoretical model developed by Ramaswamy.

PACS
61.30.St - Lyotropic phases.
83.85.Rx - Extensional flow measurement.
61.10.Eq - X-ray scattering (including small-angle scattering).


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001