Estimation of thermodynamic parameters from thermal expansion coefficient of phenylbenzylidene alkyl anilines

Abstract

The thermodynamic parameters are estimated from the density data in case phenylbenzylidene alkyl anilines with alkyl chain varying from 7 to 10, 12, 14 and 16. The parameters like Moelwyn–Hughes parameter ( C 1), reduced molar volume ( V ∼ ), isochoric temperature coefficient of internal pressure ( X), Huggin's parameter ( F), Gruneisen parameter ( Γ p ), and isothermal microscopic Gruneisen parameter ( Γ) exhibit either even–odd or odd–even effect with chain length except for the case of Sharma parameter ( S o ), fraction free volume ( f) and ( A ⁎ ) a dimensionless thermal parameter which shows consistent values in all phases. However, all these parameters show discontinuity at the phase transformation (either elevation or dip depending on thermal expansion coefficient which is either directly or indirectly proportional to thermodynamic parameters respectively). The molecular free length ( L f ) computed using different expressions also shows even–odd effect with the chain length. The results are discussed with the help of literature data on other liquid crystal compounds.