Berlin 2015 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Polymer dynamics

CPP 21.4: Vortrag

Dienstag, 17. März 2015, 10:15–10:30, C 264

Studying linear and nonlinear viscoelasticity of highly entangled polymer melts with computer simulations — •Guojie Zhang, Torsten Stuehn, Kostas Daoulas, and Kurt Kremer — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany

Viscoelasticity of entangled polymeric liquids is important for both basic science and industrial applications, e.g. polymer processing. Particularly important is the regime of nonlinear viscoelastic behavior, which however is still not well understood. Using computer simulations, we focus on obtaining a molecular understanding of chain retraction process in entangled polymers under a large step-strain. Benefiting from a simulation scheme recently developed, equilibrated configurations of high molecular weight polymer melts (number of entanglements per chain Z > 100) described with microscopic details are generated. Regimes of linear and nonlinear viscoelasticity of entangled polymers are addressed by imposing a stepwise strain on these samples. In those highly entangled melts, a clear plateau modulus is observed in the linear regime (e.g. small step strain). A quantitative agreement between value of entanglement length estimated from the plateau modulus and that measured from primitive path analysis is found. To study chain retraction process in nonlinear regime, we monitor the evolution of entanglement densities and single-chain structure factor in a largely strained sample.