Dresden 2003 – scientific programme

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SYSE: Simulation and experiment

SYSE 2: Poster (gemeinsam mit SYCN und CPP)

SYSE 2.1: Poster

Tuesday, March 25, 2003, 19:00–21:00, ZEU/250

Simulations of the crystalline phase of polymers with force-field methods: Mechanical properties and melting behaviour — •Ingo Alig and Achim Raphael — Deutsches Kunststoff-Institut,Schlossgartenstr.6, D-64289 Darmstadt

The aim of this work was to test different methods for determining the mechanical properties of the crystalline phase of semicrystalline polymers. Further the melting behaviour was investigated by molecular dynamics. The crystalline cells of polyethylen (PE), polypropylene (PP) and polyetheretherketone (PEEK) were constructed and optimised. The quality of the structures were tested by comparing the simulated X-ray scattering patterns with experimental data.

Three methods were used to evaluate the elastic constants of the crystalline structures: The static method, developed by Theodorou and Suter, the fluctuation method of Parinello and Rahman, and the dynamic method, originally introduced by Berendsen et al. and adopted by Brown and Clarke. The methods were tested on PE, PP and PEEK and the results were compared to experimental data.

Successive molecular dynamic runs at different temperatures beyond the melting point were applied to the crystal cell of PEEK. Chain conformation, cell parameters and density were examined as a function of time. By this way the melting behaviour of a quasi-infinite crystal could be observed on molecular level.