Determination of relevant mechanical properties for the production process of polyethylene by using mesoscale molecular simulation techniques

ABSTRACT

In this study, we determine the strain rate and temperature-dependent mechanical material behavior as well as the glass transition temperature and coefficient of thermal expansion of polyethylene melts using molecular dynamics simulation. In order to achieve realistic chain lengths polyethylene was simulated by three different coarse-grained models of various bead sizes. All simulations are performed by using the simulation package ESPResSo++, which we extended with a regulation procedure for the simulation of tensile tests on the micro-scale. The process-relevant observables, such as the elastic modulus, yield stress, and Poisson’s ratio are investigated at the meso-level. The chain orientation and entanglement behavior show effects that precisely illuminate the experimental stress strain response, giving important hints for production process control. Summarized, we are able to successfully reproduce the characteristic stress strain response for polyethylene as observed in experiments. Thus, we establish a closer link between microscopic and macroscopic system descriptions in order to provide a deeper understanding of material properties in their production process, i.e. for changing external conditions.

KEYWORDS:

• Meso-scale simulation
• polyethylene
• tensile test
• thermo-mechanical properties
• orientation behavior

Acknowledgments

We gratefully thank Torsten Stühn and the Max Planck Institute for Polymer Research, Mainz, for technical support. We also want to thank Olaf Bruch and Wolfgang Imhof for many fruitful discussions. Financial support given by the German Federal Ministry of Education and Research within the project ”Ressourcenoptimierte Bauteilentwicklung durch systematische Verzahnung von Experiment und multiskaligen Simulationsansätzen” (ReBauVES, code: 03FH051PX4) is greatly acknowledged. Finally, Dirk Reith wants to express his sincere and deeply felt appreciation for his PhD advisor Florian Müller-Plathe. It is hard to imagine a better mentor, as Florian always found the right mix of being demanding and supportive, besides of displaying exemplary integrity and companionship as a friend and colleague.

Declaration of interest

We declare that we have no pecuniary or other personal interest, direct or indirect, in any matter that raises or may raise a conflict with the work presented in this paper.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the Bundesministerium für Bildung und Forschung [03FH051PX4].