Dynamics and shear orientation behavior of a main-chain thermotropic liquid crystalline polymer Academic Article uri icon


  • The dynamics and shear orientation behavior of a model thermotropic liquid crystalline polymer (DHMS-7,9) were characterized by mechanical rheometry and in situ wide angle X-ray diffraction (WAXD). In the nematic phase (between 120 and 192C), DHMS-7,9 shows a three-region flow curve accompanied by a strong and relatively constant orientation over the entire shear rate range. A mysterious mesophase occurs between 92 and 120C that has much higher viscosity than that of the nematic phase and a monotonically shear thinning flow curve. In this phase, a striking flip of the orientation from the flow direction to the vorticity direction occurs below a critical shear rate. This orientational flipping is reversible in response to step changes of temperature and/or shear rate. Examination of the linear viscoelastic behavior suggests certain rheological similarities between the x-phase and layered fluids.

published proceedings


author list (cited authors)

  • Zhou, W. J., Kornfield, J. A., Ugaz, V. M., Burghardt, W. R., Link, D. R., & Clark, N. A.

citation count

  • 53

complete list of authors

  • Zhou, WJ||Kornfield, JA||Ugaz, VM||Burghardt, WR||Link, DR||Clark, NA

publication date

  • August 1999