Hydrogen Gas Transport in Semi-Crystalline Polyethylene
ORAL
Abstract
We investigate the molecular details of hydrogen gas transport in semi-crystalline polyethylene (PE) using united-atom molecular dynamics (MD) simulations. Simulations used the TraPPE united atom potential for the polymer and a simple single-site model for the hydrogen molecules. Hybrid grand canonical Monte Carlo/MD simulations were used to determine the solubility of H2 in the amorphous phase of PE as a function of external pressure, up to 90 GPa. The diffusivity of H2 in the amorphous phase was found to decrease with increasing pressure and is strongly correlated with increases in polymer density with increasing pressure. Systems with crystalline/amorphous interfaces were constructed to investigate the dynamics in the interphase region. Hydrogen does not enter the crystalline regions and instead is confined to the amorphous interphase region. This confinement leads to a decrease in diffusivity as compared with the amorphous phase at a comparable pressure and density. The distribution of free volume is correlated with the H2 diffusivity.
*This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE's National Nuclear Security Administration under contract DE-NA-0003525.
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Presenters
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Amalie L Frischknecht
- Sandia National Laboratories