UCSB researchers challenge our understanding of the flow behavior of polymeric fluids
MELVILLE, N.Y., July 10, 2025 /PRNewswire/ — A team of researchers from University of California, Santa Barbara and a collaborator from Anton Paar have been selected to receive the 2025 Journal of Rheology Publication Award.
University of California, Santa Barbara’s Michael C. Burroughs, Yuanyi Zhang, Christopher M. Bates, Matthew E. Helgeson, and L. Gary Leal, working together with Anton Paar’s Abhishek Shetty, have received the award for their paper, “Flow-concentration coupling determines features of nonhomogeneous flow and shear banding in entangled polymer solutions,” published in the November 17, 2022 issue of the Journal of Rheology.
The paper investigated the relationships between flow-concentration coupling and shear banding in entangled polymer solutions. According to Prof. Leal, it has been assumed in most previous studies that polymeric liquids remain homogeneous under flow. However, recent research by his group and others demonstrated that it was theoretically possible for such liquids to undergo flow-induced “demixing” — leading, in a simple shear flow device, to two or more distinct values of concentration and shear rate, the latter being the chief characteristic of “shear banding.”
These predictions, while potentially important to our understanding of the flow behavior of polymeric fluids, had not been confirmed experimentally. In the winning paper, Burroughs and his PhD advisors, Helgeson and Leal, confirmed the predictions by means of a novel experimental protocol, developed in collaboration with Shetty, and aided by chemical modification of the polymers by Zhang and Bates. This methodology allowed simultaneous measurement of mechanical stress, velocity, and concentration profiles in a Couette shear flow device.
“This research represents a major step forward and is significant because it shows that the long-held assumption of macroscopic homogeneity, which is the basis of most theories of polymeric flows, is generally incorrect,” said Leal. “Future research will determine the practical significance of this conclusion for polymer processing and other applications.”
Journal of Rheology Editor-in-Chief, Prof. Dimitris Vlassopoulos, agreed, calling the work “transformative” and noting it utilizes state-of-the-art experiments, including rheometry, particle tracking velocimetry, and rheo-fluorescence measurements of polymer concentration on well-characterized materials, coupled with theoretical modeling.
“The results provide a framework to design new experiments and eventually construct operating diagrams for flowing polymer solutions,” said Prof. Vlassopoulos. “Highlighting articles like this one cements the prominent position of our journal in the field and further promotes the discipline of rheology in the physics and engineering communities.”
The Journal of Rheology Publication Award is conferred annually for the best paper in the preceding two years appearing in the Journal of Rheology (JOR), which is published by AIP Publishing for the Society of Rheology (SOR). The winners will receive a monetary award and special recognition at the SOR Annual Meeting.
ABOUT THE SOCIETY OF RHEOLOGY
The Society of Rheology (SOR) is composed of physicists, chemists, biologists, engineers, and mathematicians interested in advancing and applying rheology, which is defined as the science of deformation and flow of matter. The Journal of Rheology, which is published by AIP Publishing on behalf of SOR, is a vital resource for researchers working in fields as diverse as polymer physics and fluid mechanics. It presents experimental results, phenomenological models, and microscopic theories dealing with the rheological behavior of complex materials, including macromolecular, colloidal and particulate solids, and fluids. Application areas include foods, paints, plastics, lubricants, ceramics, coatings, glaciers, and biological fluids.
ABOUT AIP PUBLISHING
AIP Publishing’s mission is to advance, promote, and serve the physical sciences for the benefit of humanity by breaking barriers to open, equitable research communication and empowering researchers to accelerate global progress. AIP Publishing is a wholly owned not-for-profit subsidiary of the American Institute of Physics (AIP) and supports the charitable, scientific, and educational purposes of AIP through scholarly publishing activities on its behalf and on behalf of our publishing partners.
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