Theory of Linear Viscoelasticity for Single-Phase Nematic Mixtures

Abstract

A macroscopic model for incompressible homogeneous (single phase) binary nematic mixtures under isothermal conditions is given; the model is restricted to two miscible nematic liquid crystals. The rheological model is a generalization of the standard Ericksen's nematorheological model for single component uniaxial rod-like nematic liquid crystals. The theory is used to characterize the linear viscoelasticity of the nematic mixture when subjected to small amplitude oscillatory shear. Mixture elasticity is shown to predict a frequency dependence of the dynamic viscosity (η′ and η“) essentially identical to those obtained using Frank elasticity and molecular elasticity. The composition dependence of the storage G' and loss modulus G” is found to be nonlinear, and stronger at low frequency than at high frequency.

Key Words:

• Macroscopic theory
• nematic mixtures
• linear viscoelasticity
• storage and loss moduli
• dynamic viscosity.