Abstract
The high pressure dilatometry of n-perfluoroeicosane (C20F42) was carried out in the isothermal compressing process at 296 K and isobaric heating processes at various pressures up to 500 MPa. The dilatometry in the isothermal compressing process at 296 K showed the possibility that there are two second-order transition points at about 200 and 250 MPa, which could not be detected by high pressure differential thermal analysis carried out in the previous work. From the data of the dilatometry in the isobaric heating processes, the thermodynamic parameters, enthalpy change ΔH and entropy one ΔS at two crystal-crystal transitions under high pressure, denoted by Tr3 and Tr4, were calculated based on Clausius-Clapeyron’s equation. The entropy change per one mole of repeating units, ΔSc, in the pressure region between 400 and 500 MPa is 1.5–1.8 and 0.7–0.9 JK−1mol−1 at Tr3 and Tr4, respectively, which indicate that moderate rotation of molecular chains starts at Tr3 and then becomes more active at Tr4 in the heating process under high pressure.
Similar content being viewed by others
Article PDF
References
S. Tsubakihara and M. Yasuniwa, Polym. J., 24, 421 (1992).
B. Wunderlich, M. Möller, J. Grebowicz, and H. Baur, “Conformational Motion and Disorder in Low and High Molecular Mass Crystals,” Adv. Polym. Sci., 87, Springer-Verlag, Berlin, 1988, Chapter 1.
H. Schwickert, Doctoral Thesis, Universität Mainz, 1984.
S. Taki, T. Takemura, and K. Matsushige, Jpn. J. Appl. Phys., 30, 888 (1991).
S. Tsubakihara and M. Yasuniwa, in preparation.
G. R. Strobl, J. Polym. Sci., Polym. Symp., 59, 121 (1977).
K. Takamizawa, Netsu Sokutei, 16(3), 112 (1989).
M. G. Broadhurst, J. Research Natl. Bur. Standards, Sect. A, 66, 241 (1962).
B. Wunderlich, “Macromolecular Physics,” Vol. 3, Academic Press, New York, N.Y., 1980, Chapter 8.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tsubakihara, S., Higashi, K., Taki, S. et al. High Pressure Dilatometry of n-Perfluoroeicosane. Polym J 24, 777–781 (1992). https://doi.org/10.1295/polymj.24.777
Issue Date:
DOI: https://doi.org/10.1295/polymj.24.777