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J. Phys. IV France
Volume 113, January 2004
Page(s) 35 - 38

J. Phys. IV France
113 (2004) 35
DOI: 10.1051/jp4:20040008

Thermal and X-ray measurements on n-hexatriacontane (C 36H 74)

F. Mina1, T. Asano1, D. Mondieig2, A. Würflinger3 and C. Josefiak3

1  Faculty of Science, Shizuoka University, Ohya 836, 422-8529 Shizuoka, Japan
2  CPMOH, UMR 5798 au CNRS, University Bordeaux I, 33405 Talence, France
3  Institute of Physical Chemistry II, Ruhr-University, 44780 Bochum, Germany

The polymorphism of n-hexatriacontane (C 36H 74) was investigated by X-ray diffraction and DSC thermal analysis. C 36H 74 displays at least two stable monoclinic phases and a rotator phase. Starting from a solution-grown sample of very high purity the following phases are observed with increasing temperature: M011 < 345K < M101 < 346K < RIII < 348K < liquid. Depending on the thermal treatment also other forms may be obsaved. During these transitions, both the crystalline volume and the lamellar thickness increase. The higher order reflections of the layer structure was precisely measured by X-ray diffraction. Using a Fourier synthesis, electron density profiles of the three phases were analysed. The results show that the interlamellar structure is disturbed by inaeasing molecular motions with elevating temperatures. For some homologous alkanes also p(T) phase diagrams and binary systems have been studied.

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