Videos

Rheo-NMR of unusual shear banded flow in wormlike micelles

Presenter
September 18, 2009
Keywords:
  • Molecular structure
MSC:
  • 92E11
Abstract
In the study of shear banding phenomena in wormlike micelles, Rheo-NMR has proven of especial value, not only indicating the clear existence of shear bands, but also that they are associated with fluctuations, and sometimes, with molecular alignment. The subtlety of the correspondence (or lack of correspondence) between birefringence effects and shear banded flow has also been revealed. Recent measurements of shear-banded flow under Couette flow of the micellar system cetylpyridinium chloride and sodium salicylate (CPyCl/NaSal) indicate that shear banding fluctuations that are inconsistent with the usual lever rule picture. We have also used Rheo-NMR to investigate the flow and alignment properties of worm-like micelles formed by a 5% w/w solution of the BASF difunctional block copolymer non-ionic surfactant, Pluronic P105 in water along with 4.3% w/v 1-phenylethanol-d5. A variety of bizarre shear-banding and alignment behaviours are observed, along with both stable and fluctuating flows.