Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 29: Crystallisation, Nucleation and Self assembly

CPP 29.7: Vortrag

Mittwoch, 28. März 2012, 17:15–17:30, C 243

Disentanglement during the crystallization of polymers — •Chuanfu Luo and Jens-Uwe Sommer — Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, 01069 Dresden

Long linear polymers are highly entangled in melts while they are folded and packed in crystals. Thus polymer crystallization can lead to some degree of disentanglement of the resulting semi-crystalline material. However this disentanglement process is very difficult to observe in experiments. By using molecular dynamics (MD) simulations combined with primitive path analysis (PPA)[1], we can directly reveal the structural changes of polymer chains as well as the changes of entanglement during the crystallization. The PPA can give the approximated entanglement length from the topology of an instantaneous conformation without running a long-time rheology simulation. By using PPA we analyzed the simulation results of slowly continuous cooling, annealing and self-seeding processes[2]. We show that polymers disentangle during crystallization and continue to disentangle during annealing. The changes of approximated entanglement density at different regions (crystallized Vs. melt) will also be discussed.

[1] R. Everaers et al., Science 303, 823 (2004)

[2] C.-F. Luo and J.-U. Sommer, Macromolecules 44, 1523 (2011)