Thermophysical study of lead(II)n-alkanoates by DSC, optical microscopy, FTIR and Raman spectroscopy
作者:
A.Sanchez Arenas,
M.V. Garcia,
M.I. Redondo,
J.A. R. Cheda,
M.V. Roux,
C. Turrion,
期刊:
Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 18,
issue 3
页码: 431-441
ISSN:0267-8292
年代: 1995
DOI:10.1080/02678299508036642
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Thirteen members of the lead(II)n-alkanoate series (from then-hexanoate to then-octadecanoate) have been synthesized, purified, and studied by differential scanning calorimetry, polarizing light microscopy, and FTIR and Raman spectroscopy. A solid-solid transition was found for all members of the series. A mesomorphic state, implying a fusion and a clearing point, was identified as smectic C, and was present only in the lower members of the series below then-tridecanoate. The higher members form the isotropic liquid through a regular fusion. Temperatures and enthalpies for the phase transitions have been measured and the corresponding entropy changes calculated. Heat capacity measurements between 280 K and 400 K were also carried out. A study of these magnitudes versus number of carbons was made. The solid phase previous to the liquid crystal in the lower members and to the isotropic liquid in the higher members could be identified as a ‘condis’ crystal (conformationally disordered phase) by an FTIR versus temperature study.
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