Rheology of nematic monodomains in small amplitude oscillatory shear

Abstract: We revisit the classical problem of the viscoelastic response of nematic liquid crystal polymers to small amplitude oscillatory shear. A multiple timescale perturbation analysis is applied to the Doi-Hess mesoscopic orientation tensor model to describe key features observed in numerical simulations of longtime experiments. First, there is a very slow timescale drift in the envelope of the oscillations of the major director. Second, there are bistable asymptotic states distinguished in that they are precisely the zero stress orientational distributions. Third, the drift dynamics and asymptotic mean director angle are determined by the initial orientation of the director, not by material properties. Finally, the director drift leads to a predicted long time decrease in the storage and loss moduli, consistent with experimentally in observations.

It is joint work with Greg Forest.