Regensburg 2013 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 33: Poster II

DY 33.17: Poster

Thursday, March 14, 2013, 17:00–19:00, Poster C

Excess entropy scaling of viscosity and diffusivity of model polymeric systems — •Evangelos Voyiatzis, Florian Müller-Plathe, and Michael Böhm — Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany

The range of validity of empirical excess entropy scalings for diffusivity and viscosity as proposed independently by Rosenfeld and Dzugutov is tested for a model system of monodisperse Lennard-Jones chains. They are long enough to be considered as entangled. Thus, the effect of entanglements on such types of scaling can be quantified. Different ways of estimating the excess entropy based on either conformational or thermodynamic information are explored. The excess entropy is calculated directly by thermodynamic integration. The excess entropy can be approximated via a thermodynamic modeling by employing the self-associating fluid theory. The detected correlations between the various conformational and thermodynamical estimations of the excess entropy are thoroughly investigated. The conformational route for a system with short-range interactions appears to be the more suitable way.The dependence of all parameters appearing in the excess entropy scaling relationships on the chain length is thoroughly examined. The relation of the scaling parameters of the viscosity and diffusion coefficient are in line with the prediction of the Stokes-Einstein law.