Measuring the structure and equation of state of polyethylene terephthalate at megabar pressures

J Lütgert,A M Saunders,N J Hartley,S H Glenzer,A Ravasio,M Schölmerich,L B Fletcher,T Vinci,T Döppner,R W Falcone,D O Gericke,E E Mcbride,A K Schuster,D Kraus,K Voigt,T E Cowan,Melanie Rödel ,Shaughnessy Brown ,Aidan Garcia ,H J Lee ,A Pełka ,Philip Heimann ,Peihao Sun ,Irene Prencipe ,Eric Cunningham ,Maximilian Schörner ,A Benuzzi‐Mounaix ,Jan Vorberger ,Eric Galtier

doi:10.1038/s41598-021-91769-0

Abstract

We present structure and equation of state (EOS) measurements of biaxially orientated polyethylene terephthalate (PET, ({hbox {C}}_{10} {hbox {H}}_8 {hbox {O}}_4)_n, also called mylar) shock-compressed to (155 pm 20) GPa and (6000 pm 1000) K using in situ X-ray diffraction, Doppler velocimetry, and optical pyrometry. Comparing to density functional theory molecular dynamics (DFT-MD) simulations, we find a highly correlated liquid at conditions differing from predictions by some equations of state tables, which underlines the influence of complex chemical interactions in this regime. EOS calculations from ab initio DFT-MD simulations and shock Hugoniot measurements of density, pressure and temperature confirm the discrepancy to these tables and present an experimentally benchmarked correction to the description of PET as an exemplary material to represent the mixture of light elements at planetary interior conditions.

Highlights

We present structure and equation of state (EOS) measurements of biaxially orientated polyethylene terephthalate (PET, (C10H8O4)n, called mylar) shock-compressed to ( 155 ± 20 ) GPa and (6 000 ± 1000 ) K using in situ X-ray diffraction, Doppler velocimetry, and optical pyrometry
Comparing the resulting diffraction patterns to predictions made on the basis of density functional theory molecular dynamics (DFT-MD) simulations provides insight into the microscopic structure and an estimation for the conditions inside the target
The X-ray diffraction (XRD) experiment was performed at the Matter in Extreme Conditions (MEC) endstation[14,15] of the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory

Summary

Introduction

We present structure and equation of state (EOS) measurements of biaxially orientated polyethylene terephthalate (PET, (C10H8O4)n , called mylar) shock-compressed to ( 155 ± 20 ) GPa and (6 000 ± 1000 ) K using in situ X-ray diffraction, Doppler velocimetry, and optical pyrometry. EOS calculations from ab initio DFT-MD simulations and shock Hugoniot measurements of density, pressure and temperature confirm the discrepancy to these tables and present an experimentally benchmarked correction to the description of PET as an exemplary material to represent the mixture of light elements at planetary interior conditions. Temperatures around 2000 K to 8000 K prevail at pressures up to several 100 GPa1,2 Such conditions fall within the ‘warm dense matter’ (WDM) regime, in the transition from condensed matter to the plasma state. In such environments, quantum effects have to be taken into account while temperature- and/or pressure-induced ionization or metallization start to play a prominent role[3]. To avoid transmission of the driving pulse through the target before an absorbing corona has been formed, the sample was coated with 100 nm aluminium

Methods

Conclusion