Superposition and universality in the linear viscoelasticity of Leslie–Ericksen liquid crystals

Abstract

The linear viscoleasticity of seven lyotropic and thermotropic liquid crystalline polymers is characterized using the Leslie–Ericksen equations of defect-free nematodynamics for small amplitude oscillatory capillary Poiseuille flow, using analytical, numerical, and scaling methods. The experimentally measured seven data sets correspond to shear flow-aligning and shear nonaligning materials. The predicted equivalent rheological responses between these two classes of polymers demonstrate the universality of nematodynamics. Principles of superposition are developed, applied, and shown to be accurate in collapsing the data sets for aligning and non-aligning polymers. The scaled resonance peak in the loss tangent (G″/G′) is shown to be a universal constant for monodomain nematics.