T. Shinoda, Y. Maeda, Hisae Enokido
Oct 1, 1974
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0
Influential Citations
25
Citations
Journal
The Journal of Chemical Thermodynamics
Abstract
The heat capacity of N-(p-methoxybenzylidene)-p-n-butylaniline (mbba) was measured between 2 and 330 K with an adiabatic calorimeter. The crystal-to-nematic phase transition temperature is 295.654 K with an enthalpy of transition (3089.2±5.1) calth mol−1 and the nematic-to-isotropic phase transition temperature is 320.137 K with an enthalpy of transition (67.9±0.9) calth mol−1. A metastable solid state (intermediate state) is established below the freezing temperature by cooling from the nematic phase and then it is transformed into the stable crystalline state irreversibly with gradual heat evolution. The orientational and positional potential energies are estimated to be 3.5 to 3.6 kcalth mol−1 and 8.9 kcalth mol−1, respectively, from the experimental results on the basis of a theory of translational and orientational melting to liquid crystals. The purity of the sample is calculated from melting-temperature depressions and from premelting heat capacities.