Thermodynamic parameters studies in N-(p-n-ethyloxybe-nzylidene)-p-n-alkoxy anilines

ABSTRACT

From the computed thermal expansion coefficient from density variation with temperature, on N-(p-n-ethyloxybenzylidene)-p-n-alkoxy anilines, 2O.Om liquid crystalline (LC) compounds with m = 3–4 and 6–10, different thermodynamic parameters such as Sharma parameter (S_o), Huggins parameter (F), reduced volume (∼V), reduced compressibility (∼V^C1), etc., are studied using the volume expansion coefficient (α), which is estimated from density in isotropic and liquid crystalline phases. The parameters like intermolecular free length (Lf), molecular radius (M_r), and Beyer's nonlinearity parameter (B/A) are also computed from density data for the above compounds. Except with m = 10, the rest of the compounds exhibit nematic phase where as with m = 10, the LC material shows smectic-C in addition to the nematic phase. The results are discussed in the light of these parameters variation with temperature in a particular phase in a LC molecule and with the chain length, m. The thermodynamic parameter S_o exhibits a constant characteristic value in all the compounds like other reported liquid crystalline compounds, liquids, and polymers. Further, the molecular radius, M_r, and molecular free length, L_f, are estimated and the results are compared with the literature data available.

KEYWORDS:

• Density studies
• liquid crystal compounds
• molecular radius and free length
• thermodynamic parameters

Acknowledgments

The authors, Dr. P. Pardha Saradhi and Dr. V. G. K. M. Pisipati, express their thanks to The Head, ECE Department and the Management of K.L.University, Vaddeswaram 522 502, India for providing facilities. One of the authors P. S. Sastry acknowledges Krishna University for providing some facilities.