| This work elucidates the effect of both temperature and molecular length on the conformational and structural properties as well as on the entanglement statistics of long amorphous and melted linear polyethylene (PE). A large number of PE samples are modelled in atomistic detail, with average molecular lengths ranging from C24 up to C1000 over a wide range of temperatures in the interval 300K ≤ T ≤ 600K under constant pressure (P = 1 atm). Monte Carlo (MC) simulations are performed for the generation and equilibration of polydisperse PE systems characterized by a uniform distribution of molecular lengths. By employing advanced chain-connectivity altering moves, full-scale equilibration is achieved within modest computational time even for the longest molecules (C500 and C1000) at standard conditions. All equilibrated Monte Carlo trajectories are subjected to direct geometrical analysis which provides the primitive paths and intermolecular entanglements from the corresponding atomistic chains. Simulation findings regarding characteristic ratio, density and packing, as quantified through the intra- and intermolecular pair distribution functions and the static structure factor, are in excellent agreement with available experimental data. The primitive path analysis reveals the dependence of the entanglement spacing, the population of entanglements along a chain and the tube diameter on chain length and temperature. The average contour length, < Lpp >, number of entanglements, < Z >, and entanglement spacing, < Ne >, are found to exhibit a simple exponential-type of dependence on temperature. The predicted value for the plateau modulus (1.7 - 1.9 MPa) based on our simulations is in excellent agreement with experimental values.
for LaTeX users @article{KFoteinopoulou2009-113,
author = {K. Foteinopoulou and N. C. Karayiannis and M. Laso and M. Kr\"oger},
title = {Structure, dimensions, and entanglement statistics of long linear polyethylene chains},
journal = {J. Phys. Chem. B},
volume = {113},
pages = {442-455},
year = {2009}
}
\bibitem{KFoteinopoulou2009-113} K. Foteinopoulou, N.C. Karayiannis, M. Laso, M. Kr\"oger,
Structure, dimensions, and entanglement statistics of long linear polyethylene chains,
J. Phys. Chem. B {\bf 113} (2009) 442-455.KFoteinopoulou2009-113
K. Foteinopoulou, N.C. Karayiannis, M. Laso, M. Kr\"oger
Structure, dimensions, and entanglement statistics of long linear polyethylene chains
J. Phys. Chem. B,113,2009,442-455 |
mk@mat.ethz.ch
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