Browsing by Author "Li, Yanfei"

Now showing 1 - 1 of 1

Nonlinear rheology of polymers: Single-molecule elongation of large circular DNA and shear of highly entangled solutions
(2016-05) Li, Yanfei; McKenna, Gregory B.; Simon, Sindee L.; Hedden, Ronald C.; San Francisco, Michael; Huffman, Lynn
In the field of polymer rheology, there is a vast variety of important phenomena worth a deep investigation. One of them is that under a strong flow, the chain configurations of the polymers change with the flow, leading to the nonlinearity in the viscoelasticity. Typical examples are shear thinning, and strain hardening. The present work focuses on understanding how polymers behave under strong nonlinear viscoelastic shear flow, and further, how the rheological flow behavior changes as a function of the molecular structures and flow geometries. We present results of a study of the shear flow properties of entangled polymer solutions, where chain-chain interactions, i.e., entanglement effects, dominate the flow behavior. In particular, we want to answer the question as to what does the flow field look like under a strong shear flow? Is the deformation field homogeneous or heterogeneous? The answer to this question affects how theorists develop molecular models, how experimentalists explain their results, and how researchers understand phenomena such as spurt flow observed during extrusion processes. Gears are switched to the rheology of polymers at the single-molecule level. Specifically, we compare the elongational flow properties of polymers of different chain architectures, i.e., circular versus linear polymers. The answer to this problem provides fundamental knowledge of chain dynamics for an architecture that remains little investigated.