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Abstract  

This work reports a non-isothermal kinetics of the melting and the nematic to isotropic (N–I) phase transitions of the pentylcyanobiphenyl (5CB) liquid crystal compared with octylcyanobiphenyl (8CB) liquid crystal using calorimetric technique. Temperature scans and heating rate scans were performed for 5CB and 8CB from 280 to 333 K at various rates using differential scanning calorimetry from 0.5 to 20 K min−1. Double activation was observed for 5CB for two heating rate regimes whereas 8CB indicated single activation only. The 5CB has smaller enthalpy and entropy of the transitions and needs larger activation than 8CB. This kinetic change can be explained in terms of the length scale and mobility of the liquid crystal molecules.

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Abstract  

The results of nematic liquid crystal - isotropic liquid phase transition study by the method of differential scanning calorimetry for inclusion compounds - mesoporous aluminosilicate molecular sieves of MCM-41 type (including Cu-exchanged samples) with encapsulated in inner-crystalline space nematic liquid crystal (5CB), as well as IR spectroscopic data for such compounds were represented. It was shown, that the 5CB molecules are able to interact with the active centers in the MCM-41 channels forming strong enough bonds of -C≡N⋅⋅⋅H-O- type. The relative amount of 5CB molecules interacting with the walls of channels and those retaining ‘liquid crystalline’ state in binary systems of molecular sieves MCM-41 and CuMCM-41 was estimated. This conclusion was confirmed by the data obtained from differential scanning calorimetry measurements.

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. Sharma , D 2010 Non-isothermal kinetics of melting and nematic to isotropic phase transitions of 5CB liquid crystal . J Therm Anal Calorim 102 : 627 – 632 10.1007/s10973-010-0837-2 . 2

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. Sharma , D 2010 Non-isothermal kinetics of melting and nematic to isotropic phase transitions of 5CB liquid crystal . J Therm Anal Calorim 102 : 627 – 632 10.1007/s10973-010-0837-2 . 15

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-010-0899-1 . 16. Sharma , D 2010 Non-isothermal kinetics of melting and nematic to isotropic phase transitions of 5CB liquid crystal . J Therm Anal Calorim. 102 : 627 – 632 10.1007/s10973

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