Solid-state phase transitions of polytetrafluoroethylene crystals studied with an ultra-high-pressure ac calorimeter

• Published in: Journal of thermal analysis and calorimetry Vol. 113; no. 3; pp. 1645 - 1650
• Main Authors: Moriwaki, Sotaro, Wada, Masahiro, Saruyama, Yasuo, Yao, Haruhiko
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Dordrecht Springer Netherlands 01.09.2013; Springer
• Subjects: Analysis; Analytical Chemistry; Applied sciences; Boundaries; Chemistry; Chemistry and Materials Science; Exact sciences and technology; Fluorine compounds; Inorganic Chemistry; Measurement Science and Instrumentation; Organic polymers; Physical Chemistry; Physicochemistry of polymers; Polymer Sciences; Polytetrafluoroethylene; Properties and characterization; Thermal and thermodynamic properties; Heat capacity; Calorimetry; PTFE; Phase transition; High pressure; Calorimeter; Tetrafluoroethylene polymer; Crystals; Phase transitions; Operating conditions; Thermal properties; Solid state; Phase transformation; Pressure effect; Thermal analysis
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-013-3194-0

The solid-state phase transitions of polytetrafluoroethylene crystals have been studied with an ultra-high-pressure ac calorimeter developed in the authors’ laboratory. The temperature dependence of heat capacity has been measured at various pressures from 0.1 to 580 MPa. It was found that excess heat capacity had long tails around the phase transition temperatures. A phase diagram was drawn and compared with reported one. In the high-temperature phase called phase I, the boundary of different phases was confirmed in this work.