Thermo acoustic parameters in the nematic and isotropic phases of 5CB and tetraethyl methane in 5CB

Abstract

The addition of non-rod like solute impurity to a liquid crystalline solvent leads to some exciting results such as depression of nematic–isotropic transition temperature and the formation of two-phase region. In view of this, specific volume and thermal expansion studies in the nematic and isotropic phases of p- n-pentyl- p 1-cyanobiphenyl (5CB) and dilute solution of the quasispherical solute tetraethyl methane were considered. From these results thermo acoustic parameters such as isochoric temperature coefficient of internal pressure ( X), isochoric volume expansivity ( X 1), the reduced compressibility ( β ∼), the reduced volume ( V ∼), isothermal microscopic Gruneisen parameter ( Γ), Huggins parameter ( F), fractional free volume ( f) and Sharma parameter ( S o) are estimated both in nematic and isotropic regions. Using the data given by Oweimreen et al. [G.A. Oweimren, A.K. Shihab, K. Halhouli, S.F. Sikander, Mol. Cryst. Liq.Cryst. 138 (1986) 327] variations of these thermo acoustic parameters with temperature and two phase region are critically examined.