Evidence for Crystalline Structure in Dynamically-Compressed Polyethylene up to 200 GPa

Journal Article · 11 March 2019 · Scientific Reports

DOI: https://doi.org/10.1038/s41598-019-40782-5 · OSTI ID:1619502

Hartley, N. J. ; Brown, S.; Cowan, T. E. ; Cunningham, E.; Döppner, T.; Falcone, R. W.; Fletcher, L. B.; Frydrych, S.; Galtier, E.; Gamboa, E. J.; Laso Garcia, A.; Gericke, D. O. ; Glenzer, S. H.; Granados, E. ; Heimann, P. A.; Lee, H. J.; MacDonald, M. J. ; MacKinnon, A. J.; McBride, E. E.; Nam, I. ; Neumayer, P.; Pak, A.; Pelka, A.; Prencipe, I.; Ravasio, A.; Rödel, M.; Rohatsch, K.; Saunders, A. M.; Schölmerich, M.; Schörner, M.; Schuster, A. K.; Sun, P.; van Driel, T.; Vorberger, J.; Kraus, D.

Abstract We investigated the high-pressure behavior of polyethylene (CH ₂ ) by probing dynamically-compressed samples with X-ray diffraction. At pressures up to 200 GPa, comparable to those present inside icy giant planets (Uranus, Neptune), shock-compressed polyethylene retains a polymer crystal structure, from which we infer the presence of significant covalent bonding. The A 2 /m structure which we observe has previously been seen at significantly lower pressures, and the equation of state measured agrees with our findings. This result appears to contrast with recent data from shock-compressed polystyrene (CH) at higher temperatures, which demonstrated demixing and recrystallization into a diamond lattice, implying the breaking of the original chemical bonds. As such chemical processes have significant implications for the structure and energy transfer within ice giants, our results highlight the need for a deeper understanding of the chemistry of high pressure hydrocarbons, and the importance of better constraining planetary temperature profiles.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-76SF00515; AC52-07NA27344; SC0018298
• OSTI ID: 1619502
• Journal Information: Scientific Reports, Journal Name: Scientific Reports Journal Issue: 1 Vol. 9; ISSN 2045-2322
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United Kingdom
• Language: English