Interdisciplinary Seminar in Nonlinear Science

Title: Laminar flows of nematic polymers: molecular theory and averaged descriptions
Speaker: Greg Forest
Speaker Info: University of North Carolina at Chapel Hill
Brief Description:
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Nematic polymers are pervasive in biological as well as synthetic "soft matter" materials, and are responsible for remarkable material properties ranging from strength, electrical and thermal conductivity, and impermeability. These macromolecules are distinguished by highly anisotropic shapes, so that collectively, above a critical concentration, a spontaneous ordering transition occurs (the isotropic- nematic phase transition). The Tobacco Mosaic Virus and spider silk are rod-like polymers, whereas nano-clays and carbon pitch are platelets. Bulk properties of nematic polymer and nano-composite materials are controlled by features, dynamical and morphological, which are created during flow processing. This lecture summarizes work of our research group on theory, modeling, and simulation of nematic polymers in laminar flows. Theory is based on the Doi kinetic theory for flowing, anisotropic macromolecules with a distortional elasticity potential, along with mesoscopic and continuum approximations. Regarding behavior, we focus first on monodomain bulk attractors in linear flows, which are the precursors to structure formation. We then model onset and evolution of spatial morphology in the flow between shear plates. We report various unexplained phenomena which pose interesting applied mathematical problems and which, we contend, are fundamental to any control strategy for flow-processed macromolecular materials. Our research group includes Qi Wang, Florida State, Ruhai Zhou, UNC-CH, and Hong Zhou, UC-Santa Cruz, together with graduate students Eric Choate, Joohee Lee, and Xiaoyu Zheng at UNC-CH.
Date: Thursday, December 5, 2002
Time: 2:00PM
Where: Tech M416
Contact Person: Mary Silber
Contact email: m-silber@northwestern.edu
Contact Phone: 847-491-8782
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