A Study of the Pressure-Induced Solidification of Polymers.

By using a self-designed pressure-jump apparatus, we investigated the melt solidification behavior in the rapid compression process for poly-ethylene-terephthalate (PET), polyether-ether-ketone (PEEK), isotactic polypropylene (iPP), high-density polyethylene (HDPE), and the living polymer sulfur. The experimental results clearly show that crystallization could be inhibited, and some melts were solidified to the full amorphous state for PET, PEEK, and sulfur. Full amorphous PEEK that was 24 mm in diameter and 12 mm in height was prepared, which exceeded the size obtained by the melt quenching method.

Pressure-jump induced rapid solidification of melt: a method of preparing amorphous materials.

By using a self-designed pressure-jump apparatus, we investigated the melt solidification behavior in rapid compression process for several kinds of materials, such as elementary sulfur, polymer polyether-ether-ketone (PEEK) and poly-ethylene-terephthalate, alloy LaAlCuCo and NdCuNiAl. Experimental results clearly show that their melts could be solidified to be amorphous states through the rapid compression process. Bulk amorphous PEEK with 24 mm in diameter and 12 mm in height was prepared, which exceeds the size obtained by melt quenching method.

In situ crystallization of low-melting ionic liquid [BMIM][PF6] under high pressure up to 2 GPa.

To develop a new practical method of purifying and recycling ionic liquids, we performed direct microscopic observations and in situ crystallization of low-melting ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]), in detail by high pressure Raman spectroscopy. Compression of [BMIM][PF(6)] was measured under pressures up to about 2.0 GPa at temperatures 293-353 K by using a high pressure diamond anvil cell (DAC).

Phase transition of [C(n)-mim][PF6] under high pressure up to 1.0 GPa.

Behavior of the phase transition of an ionic liquid, [Cn-mim][PF(6)], has been investigated under pressures up to 1.0 GPa by using a high-pressure differential thermal analysis (DTA) apparatus. The T versus P phase diagrams of [BMIM][PF(6)] and [EMIM][PF(6)] are constructed.

Brillouin scattering studies of liquid argon at high temperatures and high pressures.

Brillouin scattering measurements were performed on liquid argon in a diamond anvil cell at various solidification points up to 503 K. With the measured results from the 60 degree platelet- and 180 degree back-scattering geometries, the sound velocity, refractive index, experimental equation of state, and adiabatic bulk modulus of liquid argon as a function of pressure were determined. The discrepancy between experimental and previous calculated equation of state indicates that the many-body contribution to the density of liquid argon increases with increasing pressure and decreases with increasing temperature.