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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 42: Polymer Physics IV

CPP 42.4: Talk

Friday, March 27, 2009, 11:15–11:30, ZEU 160

Coexistence of Melting and Growth during Heating a Semi-crystalline Polymer: a MD simulation — •Chuanfu Luo and Jens-Uwe Sommer — Leibniz Institute of Polymer Research Dresden, Dresden, Germany

We present molecular dynamics (MD) simulations of the cooling/heating of semi-crystalline polymers. Using a highly parallelized code we are able to study chains up to a length of 1000 repeat units using a coarse grained polymer model [1,2]. It is the first time that a clear multi-stage melting process during the heating of a semi-crystalline polymer is analyzed by MD simulations. The step-by-step melting of different sized micro-crystalline-domains (MCDs) can explain the multiple peaks in the curve of specific heat (c_p-T). However, melting is not a simple stepwise ‘melting-recrystallization-melting’ process. The averaged stem length (lamella thickness) is increasing during the melting of smaller MCDs, and the main contribution originates from orientational correlations in the semi-melted regions and not only from local trans-trans conformations. We can interprete this a slackening of the stems which increases their mobility in reorganization processes.

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

[2] C. Luo and J.-U. Sommer, Comp. Phys. Comm. (in press)