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Journal of Thermal Analysis and Calorimetry
Authors: F. J. Martínez Casado, M. Ramos Riesco, M. I. Redondo Yélamos, A. Sánchez Arenas, and J. A. Rodríguez Cheda

; for instance: (1) the n -alkanes, that have their all - trans conformation in their chains until the melting point, preceded by a small transition (to rotator phase), (2) the lead(II) n -alkanoate series, [ 7 , 8 ] (Pb(C n ) 2 , hereafter, where C

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Abstract  

The thermally induced structural transformation of a hydrogen-bonded crystal formed from an amphoteric molecule of 6-[2-methoxy-4-(pyridylazo)phenoxy]hexanoic acid MeO was studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction measurement (XRD). Crystal form of the hydrogen-bonded crystal was measured by single crystal four circle diffractometer (Mo-Kα radiation). As a result, the crystal of MeO was stabilized by many C–H⋅⋅⋅O hydrogen bonds, and the C–H⋅⋅⋅O hydrogen bonds were broken by thermal energy reversibly. After transformation the supramolecular architecture was composed of supramolecular polymer including free-rotation pentamethylene main chains.

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system, C 14 and C 12 are partial miscible. The phase diagram has two invariants, a peritectic point and a eutectic [ 16 , 27 ]. The bulk system shows a relatively complicated behavior because of the special rotator phase in normal alkanes

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Abstract  

The study of trans- and cis-1,2-cyclohexanediol by infrared spectroscopy was performed. The variation of the maximum frequency and of the bandwidth of the OH stretching vibration give evidence of the role played by hydrogen bonding in the solid and liquid phases of both isomers and allows to follow the phase transitions. A solid rotator phase is shown for the cis compound.

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Abstract  

The enthalpy variations of pure n-tricosane (n-C23H48), pure n-pentacosane (n-C25H52) and sixteen binary mixtures were determined from 282 to 360 K. The differential enthalpy analyses were carried out on the pure components on the four terminal solid solutions, denoted βo(C23), β′o(C23), β′o(C25), βo(C25) and on the three intermediate phases, called β″1, β′1, β″2of the binary system (C23:C25) using a calorimeter of the Tian Calvet type. These variations can be represented by an analytical expression, which is derived from Einstein‘s model. The two Rotator phases β-RI and α-RII were also studied.

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