Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 63: Polymer and Molecular Dynamics II

CPP 63.7: Vortrag

Donnerstag, 15. März 2018, 11:15–11:30, C 264

Conformational relaxation of chains in highly entangled polymer melts after a large step deformation — •Hsiao-Ping Hsu and Kurt Kremer — Max Planck Institute for Polymer Research

Anisotropic stress relaxation of strongly deformed polymer melts in a non-linear viscoelastic regime and the resulting anisotropic structures of chains after isochoric elongation are studied. Both the classical Doi-Edwards tube theory and refined GLaMM tube theory incorporating contour length fluctuation, and convective constraint release predict that the process of retraction in entangled linear chains sets in immediately after the deformation, while there exist contradictions between experiment and theory. Our results of radius of gyration in the direction perpendicular to the stretching direction indicate chain retraction in the initial relaxation process. Applying the harmonic spherical expansion approach to the 2D scattering function along the parallel and perpendicular to the stretching direction, the profiles of the first anisotropic term of scattering function also qualitatively agree with the theoretical prediction by GLaMM around Rouse time. The influence of finite-size effects is also investigated. Finally, applying the primitive path analysis to the deformed polymer melts, we also observe that there exists significantly delayed equilibration processes while deformed polymer melts are relaxing.