Scattering Studies of Polymer Deformation in Flowing Solutions

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This research will employ light scattering to examine the conformations of flexible polymers in flowing solution. Emphasis will center on extensional flows, which can greatly perturb Gaussian polymer chains from their equilibrium, spherical shape. Despite its importance to many industrial processes in which macromolecules are stretched in flow, polymer structure away from equilibrium is still not well understood. Dilute solutions will be examined using low.angle light scattering, and low.angle neutron scattering will be attempted for semidilute and moderately concentrated solutions. In addition to steady measurements, a new flow device will make possible study of the transient stretching of flexible macromolecules in Lagrangian unsteady flows. Unsteady flows are typically found in such commercial applications as fiber spinning, and have been made difficult to examine systematically with conventional methods. The results of the proposed research will provide more direct, and less ambiguous, measurements of polymer conformation than can be obtained by other techniques.