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Chemical Engineering

Rheology Laboratory

Professor Denn

This research is broadly concerned with the use of rheology, non-Newtonian fluid mechanics, and polymer physics to solve problems of interest in polymer processing. He uses whatever tools are most appropriate for the problem at hand, often in collaboration with colleagues who have specific expertise: continuum theory and simulation, molecular simulation, rheological measurement, and various spectroscopies. In recent years he has focused on two problems. One is the mechanics of liquid crystalline materials, especially as the dispersed phase in a blend; the interesting issues here have to do with the effect of nematic order on droplet deformation and the structure and mechanics of the interface between a liquid crystalline polymer and a flexible polymer. The other is the cause of surface distortions during the extrusion of polymer melts, where the issues have to do with the mechanics of entangled polymer chains near a nonpolymeric surface during flow at high shear stresses. A common feature of both classes of problems, as well as others in which he is interested, is the need to understand the mechanics of polymer chains near an interface, and the effect of chain conformation on the neighboring stress field.