Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

Phase behavior and dielectric relaxation of camphor and borneol enantiomers in neat phase and their binary mixtures have been studied employing dielectric spectroscopy (20 Hz-2 MHz), differential scanning calorimetry (DSC), and X-ray diffraction techniques. Camphor and borneol form a solid solution in phase SI which is an orientationally disordered phase of fcc structure and gets supercooled during cooling. For solid solutions, two alpha- processes and a sub-Tg process are observed. The fm values of primary relaxation processes are deviating from Arrhenius behavior. The activation energy of sub-Tg process lies in the range of 11-18 kJ/mol and is of Johari-Goldstein type indicating the intermolecular nature. Sub- Tg process is perhaps the dominant process seen at higher temperatures studied by Smyth et al. (1963) and Davies et al. (1962).