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New controlled release systems produced by self-assembly of biopolymers and colloidal particles at fluid-fluid interfaces
We carried out pointwise local velocity measurements on 40 mM cetylpyridinium chloride-sodium salicylate (CPyCl-NaSal) wormlike micellar solution using high-frequency ultrasound velocimetry in a Couette shear cell. The studied wormlike solution exhibits Newtonian, shear-thinning and shear-thickening rheological behavior in a stress-controlled environment. Previous rheology, flow visualization and small-angle light/neutron scattering experiments in the shear-thickening regime of this system showed the presence of stress-driven alternating transparent and turbid rings or vorticity bands along the axis of the Couette geometry. Through local velocity measurements we observe a homogeneous flow inside the 1 mm gap of the Couette cell in the shear-thinning (stress-plateau) region. Only when the solution is sheared beyond the critical shear stress (shear-thickening regime) in a stress-controlled experiment, we observe inhomogeneous flow characterized by radial or velocity gradient shear bands with a highly sheared band near the rotor and a weakly sheared band near the stator of the Couette geometry. Furthermore, fast measurements performed in the shear-thickening regime to capture the temporal evolution of local velocities indicate coexistence of both radial and vorticity shear bands. However the same measurements carried out in shear rate controlled mode of the rheometer do not show such rheological complexity. [hide]
Scientific Board
Andreas Bausch
TU Munich, Germany ►
Peter Fischer
ETH Zurich, Switzerland ►
Anne-Marie Hermansson
SIK, Sweden ►
Martin Kroger
ETH Zurich, Germany/Switzerland ►
Erik van der Linden
Wageningen UR, The Netherlands ►
Niklas Loren
SIK, Sweden ►
Leonard Sagis
Wageningen UR, The Netherlands ►
Erich Windhab
ETH Zurich, Switzerland ►
Klaas-Jan Zuidam
Unilever, The Netherlands ►
Scientific Stuff
Manuela Duxenneuner
ETH Zurich, Switzerland ►
Sophia Fransson
SIK, Sweden ►
Nam-Phuong Humblet-Hua
Wageningen UR, The Netherlands ►
Joeska Husny
ETH Zurich, Australia/Switzerland ►
Orit Peleg
ETH Zurich, Israel/Switzerland ►
Cyrille Vezy
TU Munich, Germany ►
Varvara Mitropoulos
ETH Zurich, Switzerland ►
Associated Scientists
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SY Tee, AR Bausch, PA Janmey,
The mechanical cell
CURRENT BIOLOGY 19 (2009) R745 ►Selected conferences (co-)organized by project members
8th World Congress on Computational Mechanics WCCM8 2008
30 June - 5 July 2007, Venice, Italy ►13 May 2025
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