The Brillouin spectra were collected by 3 + 3 pass tandem Fabry Perot interferometer designed by Sandercock. A single-frequency 532 nm laser was used as Brillouin excitation source. The DAC places to bisect this scattering angle such that the difference vector, i.e., the acoustic phonon wave vector, is in the plane of the sample. Brillouin scattering experiments were performed in symmetric platelet scattering geometry. 21–23 A small annealed ruby chip was loaded into the chamber for the pressure calibration. Silicon oil was utilized as the pressure transmission medium in DAC to minimize the pressure gradient. The culet size of diamond anvils is 400 μm in diameter. 1) is used as the research object enclosed in a symmetric DAC with a large conical opening aperture. Experimental PEEK APTIV 2000 series film with thickness of 50 μm (VICTREX, T g: 143 ☌, ρ: 1.26 g cm −3, the structure of PEEK was shown in the Fig. Herein, the isothermal compressibility and pressure dependence of mechanical moduli were determined for the aromatic PEEK through high temperature high pressure Brillouin scattering upto 520 K and 13.9 GPa. To the best of our current knowledge, there is no research on the determination of mechanical properties of PEEK under high pressure, much less the simultaneous high temperature. 18–20 These characteristics make PEEK an excellent candidate material for specific applications under extreme conditions. Poly(ether ether ketone) (PEEK), as one of the most used special engineering plastic, has attracted special attention due to its high stability, excellent mechanical strength, good radiation-resistant. Contrast to the previous approaches, high pressure Brillouin scattering spectroscopy method was considered as the optimal approach, due to its accuracy, effectiveness and safety. The elastic properties and mechanical moduli of these polymers under high pressure were determined accurately, which provided an effective theoretical direction for their utility under extreme condition. The diamond anvil cell (DAC) supplies the high pressure condition. Recently, some polymer samples, such as polyolefins, polysiloxanes, and polyimide, have been investigated by high pressure Brillouin scattering spectroscopy technique, 3–11 which is a nondestructive method to provide insight into the elastic and bulk mechanical properties of optically transparent materials by measuring their acoustic velocities. 2 Moreover, various theoretical models have also been applied for the evaluation of extensive EOS data of pure polymers, polymer–solvent and polymer blends. volume behind shock waves were measured in the pressure range of 0–56 GPa. 1 The dynamical behavior of polyimide was also investigated in detail using a flyer driven by chemical explosion. The laser-driven equation-of-state (EOS) experiments were performed with emission measurements from the rear sides of a shocked target at a high laser intensity with 2.5 ns duration. Takamatsu and coworkers obtained polyimide Hugoniot data up to 0.6 TPa with good accuracy. Up to now, several approaches have been explored to achieve this goal. 1–11 Therefore, the deep knowledge of their mechanical properties under extreme conditions is essential for design and development of polymer components. Introduction The versatility of polymers has allowed them to be used extensively under extreme conditions, as various components in explosives, aerospace, submarine and heavy machinery, where the polymers witness high strain rates, high pressure, and even high temperature. Comprehensive investigation of elastic properties as a function of pressure not only provides an effective way to understand the mechanical behavior of PEEK under high temperature and high pressure, but also supplies an available theoretical direction for their practical application under extreme conditions. A typical negative thermal expansion phenomenon was observed under high temperature and high pressure, which has been explained and discussed by virtue of free volume theory. The isothermal compressibility and pressure dependence of the mechanical moduli of PEEK film were examined and determined. In this study, we chose poly(ether ether ketone) (PEEK) to study its mechanical behavior under high temperature and high pressure using Brillouin scattering coupled with an electrical resistance heating technique and diamond anvil cell device. However, there are few studies on the mechanical variation under extreme conditions. The mechanical properties of special engineering plastic have been intensively studied in recent years.
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