Polydomain model predictions of liquid crystalline polymer orientation in mixed shear/extensional channel flows

Jr Cinader, W. R. Burghardt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The Larson-Doi (LD) polydomain model is used to simulate orientation development along the centerline of slit-expansion and slitcontraction flows of liquid crystal-line polymers (LCPs). Orientation is computed using the LD structural evolution equations, subject to an imposed velocity field that accounts for the spatial variation of both shear and extension rates characteristic of this class of flows. Computed axial distributions of orientation averaged through the sample thickness are qualitatively similar to birefringence and X-ray scattering measurements of molecular orientation in similar flows of lyotropic and thermotropic LCPs. In slit-expansion flows, the simulations predict a 90°flip in orientation direction near the midplane due to transverse stretching in the expansion region. Far away from the midplane where shear gradients dominate, orientation remains primarily along the flow direction. Within the LD model, tumbling and flow aligning materials respond in a qualitatively similar manner to mixed shear and extension, although tumbling materials are systematically more susceptible to the effects of extension.

Original languageEnglish (US)
Pages (from-to)259-270
Number of pages12
JournalRheologica Acta
Volume39
Issue number3
DOIs
StatePublished - 2000

Keywords

  • Channel flows
  • Larson-Doi model
  • Liquid-crystalline polymer
  • Orientation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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