The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods
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 th...
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| Format: | Article |
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MDPI AG
2016-08-01
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| Series: | Polymers |
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| Online Access: | http://www.mdpi.com/2073-4360/8/8/291 |
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| author | Christian Lang Joachim Kohlbrecher Lionel Porcar Minne Paul Lettinga |
| author_facet | Christian Lang Joachim Kohlbrecher Lionel Porcar Minne Paul Lettinga |
| author_sort | Christian Lang |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-04-12T03:05:38Z |
| format | Article |
| id | doaj.art-fea4324f147a41aeaf9af11975fc85e8 |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-04-12T03:05:38Z |
| publishDate | 2016-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-fea4324f147a41aeaf9af11975fc85e82022-12-22T03:50:31ZengMDPI AGPolymers2073-43602016-08-018829110.3390/polym8080291polym8080291The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal RodsChristian Lang0Joachim Kohlbrecher1Lionel Porcar2Minne Paul Lettinga3ICS-3, Institut für Weiche Materie, Forschungszentrum Jülich, D-52425 Jülich, GermanyLaboratory of Neutron Scattering and Imaging, Paul Scherrer Institute, 5232 Villigen, SwitzerlandInstitut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, FranceICS-3, Institut für Weiche Materie, Forschungszentrum Jülich, D-52425 Jülich, GermanyThe 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.http://www.mdpi.com/2073-4360/8/8/291rheologysoft matterliquid crystalsteady shear flowideal rods |
| spellingShingle | Christian Lang Joachim Kohlbrecher Lionel Porcar Minne Paul Lettinga The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods Polymers rheology soft matter liquid crystal steady shear flow ideal rods |
| title | The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods |
| title_full | The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods |
| title_fullStr | The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods |
| title_full_unstemmed | The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods |
| title_short | The Connection between Biaxial Orientation and Shear Thinning for Quasi-Ideal Rods |
| title_sort | connection between biaxial orientation and shear thinning for quasi ideal rods |
| topic | rheology soft matter liquid crystal steady shear flow ideal rods |
| url | http://www.mdpi.com/2073-4360/8/8/291 |
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