Density Measurements in the Nematic and Isotropic Phases of 5CB and Dilute Solutions of Tetraethylmethane in 5CB

Abstract

Density as a function of temperature was measured in the nematic and isotropic phases of p-n-pentyl-p'-cyanobiphenyl (5CB). Similar measurements were made on six dilute solutions of the quasispherical solute Et₄C (tetraethylmethane) in 5CB. The results were used (on their own and with previous results from visual studies) to obtain β_N and β₁, the moduli of the slopes of the nematic and isotropic boundary lines in the reduced NI transition temperature (T*) vs. solute mole fraction (x ₂) diagrams. The results verify the compatibility of the density and visual methods and show that T* vs. x ₂ plots can, for all practical purposes, be considered linear in the x ₂ ranges studied.

Keywords:

• density
• phase diagram
• tetraethylmethane-5CB mixtures