Regensburg 2010 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 12: Soft Matter I
DY 12.4: Vortrag
Dienstag, 23. März 2010, 15:15–15:30, H47
Time-dependent primitive path analysis — •Jixuan Hou1, Carsten Svaneborg2, Gary Grest3, and Ralf Everaers1 — 1École Normale Supérieure de Lyon — 2University of Aarhus — 3Sandia National Laboratories
The complex viscoelastic properties of polymer liquids are due to the presence of topological constraints on a molecular scale. On a microscopic scale chains can slide past each other, but their backbones cannot cross. The standard model of polymer dynamics, the tube model, assumes that entanglements confine chain fluctuations to a narrow tube-like region along a so-called *primtive path” which follows the coarse-grained chain contour.
Primitive paths were originally introduced in a thought experiment as the shortest paths into which chains with fixed endpoints can contract without crossing each other. A few years ago, we have shown how to perform a corresponding primitive path analysis (PPA) of computer generated conformations of atomistic or coarse-grained models of entangled polymer systems. We will first present our simulation results for entangled polymer melt which cover the entire range from loosely to tightly entangled polymers. The excellent agreement demonstrates that the tube model can make parameter-free, quantitative predictions for plateau moduli on the basis of a purely topological analysis. Then, we will discuss the extension of the primitive path analysis to strained systems as well as a time-dependent version of our original, time-saving algorithm. By using the time mapping, one can obtain the precise relaxation mudulus from free-end PPA.