Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 14: Polymer Crystallization

CPP 14.2: Vortrag

Mittwoch, 29. März 2006, 14:15–14:30, ZEU Lich

What happens to entanglements during polymer crystallization? — •Hendrik Meyer — Institut Charles Sadron, CNRS UPR 22, 67083 Strasbourg, France

We developed a simplified polymer model which appeared to be very efficient for the study of polymer crystallization from the dense melt using molecular dynamics simulations [1]. Chain-folded lamellae were obtained starting from the isotropic melt with chains of N=400 monomers corresponding to 10-12 entanglement lengths. The thickness of the lamellae decreases with crystallization temperature as observed in experiments. We now reanalyzed the obtained configurations with a primitive path analysis [2] to quantify the entanglement length of the chains. We find that for fast crystallization, the entanglement length remains almost unchanged. For slower crystallization, in particular above the temperature where homogeneous nucleation of crystals was observed, some disentanglement occurs, and the entanglement length increases by about 50%. This means that the majority of entanglements is still present. They must be in the amorphous zones where the entanglement density thus increases.

[1] H. Meyer and F. Müller-Plathe, J. Chem. Phys. 115 (2001) 7807; Macromolecules 35 (2002) 1241.

[2] R. Everaers et. al., Science 304 (2004) 823.