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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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