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Article

The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods

1
ICS-3, Institut für Weiche Materie, Forschungszentrum Jülich, D-52425 Jülich, Germany
2
Laboratory of Neutron Scattering and Imaging, Paul Scherrer Institute, 5232 Villigen, Switzerland
3
Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France
*
Author to whom correspondence should be addressed.
Also at: Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
Academic Editor: Martin Kröger
Polymers 2016, 8(8), 291; https://doi.org/10.3390/polym8080291
Received: 31 May 2016 / Revised: 1 August 2016 / Accepted: 2 August 2016 / Published: 9 August 2016
(This article belongs to the Special Issue Semiflexible Polymers)
The complete orientational ordering tensor of quasi-ideal colloidal rods is obtained as a function of shear rate by performing rheo-SANS (rheology with small angle neutron scattering) measurements on isotropic fd-virus suspensions in the two relevant scattering planes, the flow-gradient (1-2) and the flow-vorticity (1-3) plane. Microscopic ordering can be identified as the origin of the observed shear thinning. A qualitative description of the rheological response by Smoluchowski, as well as Doi–Edwards–Kuzuu theory is possible, as we obtain a master curve for different concentrations, scaling the shear rate with the apparent collective rotational diffusion coefficient. However, the observation suggests that the interdependence of ordering and shear thinning at small shear rates is stronger than predicted. The extracted zero-shear viscosity matches the concentration dependence of the self-diffusion of rods in semi-dilute solutions, while the director tilts close towards the flow direction already at very low shear rates. In contrast, we observe a smaller dependence on the shear rate in the overall ordering at high shear rates, as well as an ever-increasing biaxiality. View Full-Text
Keywords: rheology; soft matter; liquid crystal; steady shear flow; ideal rods rheology; soft matter; liquid crystal; steady shear flow; ideal rods
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MDPI and ACS Style

Lang, C.; Kohlbrecher, J.; Porcar, L.; Lettinga, M.P. The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods. Polymers 2016, 8, 291. https://doi.org/10.3390/polym8080291

AMA Style

Lang C, Kohlbrecher J, Porcar L, Lettinga MP. The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods. Polymers. 2016; 8(8):291. https://doi.org/10.3390/polym8080291

Chicago/Turabian Style

Lang, Christian, Joachim Kohlbrecher, Lionel Porcar, and Minne P. Lettinga. 2016. "The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods" Polymers 8, no. 8: 291. https://doi.org/10.3390/polym8080291

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