Oscillatory shear rheology of chiral liquid crystal polymers

Document Type

Conference Proceeding

Publication Date

12-22-2009

Abstract

We employ a hydrodynamic theory for chiral liquid crystal polymers (CLCPs) to investigate the linear viscoelastic response of CLCPs to small amplitude oscillatory permeation shear flow, when the helix is oriented along the velocity direction and the orientation distortion retain the original planar structure. To predict the linear viscoelasticity, we model the system with Stokes hydrodynamic equations with viscous and nematic as well as cholesteric stresses coupled with orientational dynamics driven by the flow. The key findings are the following: in low frequency limit, both the loss modulus (G") and storage modulus (Gi) exhibit a classical frequency ? dependence (G" ? ?, Gi ? ?2) but their magnitudes are of order O(q/Er1/2 ), where 2?/q defines the pitch of the chiral liquid crystal and Er is the Ericksen number. In high frequency limit, Gi = O(q2/Er) is independent of ? while Gi = O(1)? is independent of q and Er. © 2009 Copyright SPIE - The International Society for Optical Engineering.

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