X-ray scattering studies of orientation in channel flows of a lyotropic liquid crystalline polymer

David K. Cinader, Wesley R. Burghardt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


A lyotropic solution of hydroxypropylcellulose in m-cresol has been studied in channel flows containing inhomogeneous shearing kinematics (planar Poiseuille), or mixed shearing and extensional kinematics (slit-contractions and expansions). We have used X-ray scattering as a probe of orientation, to test and extend previous birefringence measurements in the same system [Bedford BD, Burghardt WR. J Rheol 1996;40:235]. Orientation changes dramatically in contraction and expansion regions, which cannot be explained by changes in superficial velocity alone. Calculations using Ericksen's Transversely Isotropic Fluid model show that the addition of a modest amount of extension to otherwise shearing kinematics can influence alignment by perturbing tumbling orbits either into or out of the shear plane, in addition to inducing a transition from tumbling to flow aligning behavior. Away from the centerline, orientation is rotated away from the downstream direction, presumably due to streamline bending near the contraction and expansion. However, the degree of rotation is different in contraction and expansion flows.

Original languageEnglish (US)
Pages (from-to)4169-4180
Number of pages12
Issue number15
StatePublished - Jul 1999


  • Channel flows
  • Liquid-crystalline polymer
  • Molecular orientation

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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