Abstract
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. The bulk amorphous sulfur thus obtained exhibited extraordinarily high thermal stability, and an abnormal exothermic transition to liquid sulfur was observed at around 396 K. Since the solidification of melt is realized by changing pressure instead of temperature and is not essentially limited by thermal conductivity, it is a promising way to prepare fully amorphous polymers. In addition, novel properties are also expected in these polymers solidified by the pressure-jump within milliseconds.
Highlights
Alongside temperature and composition, pressure is another independent parameter that determines the structure, state, and properties of materials
PEEK is a semicrystalline polymer composed of crystalline and an amorphous phase
On the basis of the experimental results, it was made clear that the rapid compression of melt is an effective method to inhibit crystallization and prepare full amorphous polymers
Summary
Pressure is another independent parameter that determines the structure, state, and properties of materials. Cooling is the most widespread process for the solidification of melts. Compression leads to the solidification of the melts This process is thermodynamically symmetrical to the cooling process. For those polymers whose melting temperature increases with increasing pressure, compression should lead to the solidification of their melts. Pressure of melt should jump to a high value within a very short time. In this within a say verythat short. In this process, the solidification of melt is realized by changing the process, the solidification of melt is realized by changing the pressure instead of the temperature, pressure instead of the temperature, so the preparation of the amorphous phase should not be so the preparation of theconductivity.
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