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Transient shear banding in the nematic dumbbell model of liquid crystalline polymers

Adams, J. M. and Corbett, D. (2018) Transient shear banding in the nematic dumbbell model of liquid crystalline polymers Physical Review E, 97 (5), 052601. 052601-1 - 052601-15.

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Abstract

In the shear flow of liquid crystalline polymers (LCPs) the nematic director orientation can align with the flow direction for some materials but continuously tumble in others. The nematic dumbbell (ND) model was originally developed to describe the rheology of flow-aligning semiflexible LCPs, and flow-aligning LCPs are the focus in this paper. In the shear flow of monodomain LCPs, it is usually assumed that the spatial distribution of the velocity is uniform. This is in contrast to polymer solutions, where highly nonuniform spatial velocity profiles have been observed in experiments. We analyze the ND model, with an additional gradient term in the constitutive model, using a linear stability analysis. We investigate the separate cases of constant applied shear stress and constant applied shear rate. We find that the ND model has a transient flow instability to the formation of a spatially inhomogeneous flow velocity for certain starting orientations of the director. We calculate the spatially resolved flow profile in both constant applied stress and constant applied shear rate in start up from rest, using a model with one spatial dimension to illustrate the flow behavior of the fluid. For low shear rates flow reversal can be seen as the director realigns with the flow direction, whereas for high shear rates the director reorientation occurs simultaneously across the gap. Experimentally, this inhomogeneous flow is predicted to be observed in flow reversal experiments in LCPs.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
NameEmailORCID
Adams, J. M.J.Adams@surrey.ac.uk
Corbett, D.
Date : 1 May 2018
DOI : 10.1103/PhysRevE.97.052601
Copyright Disclaimer : © 2018 American Physical Society. This is a post-peer-review, pre-copyedit version of the following article: 'Transient shear banding in the nematic dumbbell model of liquid crystalline polymers'; J. M. Adams and D. Corbett; Phys. Rev. E 97, 052601 – Published 1 May 2018 and available at https://doi.org/10.1103/PhysRevE.97.052601
Depositing User : Clive Harris
Date Deposited : 25 May 2018 07:45
Last Modified : 16 Jan 2019 19:10
URI: http://epubs.surrey.ac.uk/id/eprint/846517

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