A Universal Behavior for the Ratio between the Miesowicz's Coefficients for Rigid Calamitic Molecules of Nematic Liquid Crystals

Abstract

In this work a geometrical interpretation to the ratio between the Miesowicz's coefficients will be proposed. We will show that the thermodynamic parameters describing the viscosity coefficients can be separated in two classes; those describing the orientation of the molecules, and those describing their overall behavior. This fact suggests that the ratio between any two of the Miesowicz's coefficients have a universal behavior that is dominated by the geometric orientation of the long axis of the molecules of the material during the shear flow. In order to inspect this hypothesis, the kinetic results for the viscosity's coefficients have been studied and it is shown that this theory is in accord with a universal behavior for the ratio between the Miesowicz's coefficients. Nevertheless, the experimental data does not agree with the prediction of these calculations.

Key Words:

• Rheology
• Viscosity
• Miesowicz's coefficients