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Updated: Sep 22, 2025
Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering
Published on: February 6, 2014
Spatially Resolved Concentration and Segmental Flow Alignment in a Shear-Banding Solution of Polymer-Like Micelles
A Kate Gurnon1, Carlos López-Barrón2, Matthew J Wasbrough1,3
1Center for Neutron Science, Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States.
Abstract:
We measure the spatially resolved microstructure and concentration in the plane of flow for a viscoelastic solution of polymer-like micelles comprised of mass fraction 6.0% (volume fraction 6.6%) solution of 2:1 molar ratio cetylpyridinium chloride/sodium salicylate in 0.5 mol/L NaCl/D2O through the shear banding transition. Spatially resolved flow small-angle neutron scattering measurements in the velocity-velocity gradient (1-2) plane of flow establish the local microstructure, and scanning narrow-aperture flow ultrasmall-angle neutron scattering (SNAFUSANS) measurements indicate no flow-induced concentration gradients within measurement accuracy. These results show shear banding in this solution is not associated with an isotropic-nematic transition and are fundamentally important for validating models of shear-banding complex fluids. Improvements in the SNAFUSANS method are also documented.
