Shear-induced deformation of polystyrene coils in dilute solution from small angle neutron scattering 2. Variation of shear gradient,molecular mass and solvent viscosity |
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Authors: | P. Lindner R. C. Oberthür |
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Affiliation: | (1) Present address: Institut Max von Laue-Paul Langevin, Grenoble, France;(2) Institut für Festkörperforschung der KFA Jülich, D-5170, Germany |
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Abstract: | The technique of small angle neutron scattering (SANS) has been used to study the conformation of polystyrene chains in dilute solution under a constant shear gradient. The experiments reveal a distinct anisotropy of the molecular dimensions with regard to the directions parallel and perpendicular to the flow direction on the 2D-multidetector. The deformation ratio of the single polymer chain (R2/Riso2)–1 as a function of the reduced shear gradient=([] · · MwG)/RT shows a transition from the ideal2-behaviour for dynamic infinitely flexible coils found at small gradients, to a behaviour with smaller increase at larger. These results are qualitatively consistent with the theory of Cerf for a polymer with finite internal viscosity in a shear gradient. At low(<1), a better agreement with the model of a free-draining coil (Rouse behaviour) than with the Zimm model is observed. |
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Keywords: | Shear gradient Couette flow small angle neutron scattering polymer conformation polystyrene Rouse behaviour internal viscosity |
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