Polymer Science Faculty Research


Rheological study of chain dynamics in dilute binary polymer mixtures

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Publication Date

Spring 2005


Recent progress toward a more realistic understanding of chain dynamics in entangled binary mixtures has prompted us to examine in detail the nature of probe chain dynamics in binary mixtures in the dilute limit. We have carried out theoretical analyses to determine the solution rheological signatures of various types of chain dynamics and subsequently performed rheological measurements on a number of binary mixtures. We found in general agreement with the theoretical predictions that there are indeed several interesting regions including the familiar Zimm solution behavior, the Rouse-like solution behavior for both nonentangled and entangled matrices, and a Stokes-sphere dynamics involving a probe chain in a well-entangled “solvent”. These experimental results reveal a high level of interplay between the probe and matrix chain lengths that dictates the actual probe chain dynamics. For example, a longer matrix chain is more effective in screening both excluded volume and hydrodynamic interactions and in delaying the onset of the nonlinear concentration dependence of the zero-shear solution viscosity.



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