Smectic rheology close to the smectic-nematic transition

¹  Department of Chemistry, Nagaoka University of Technology - Niigata 940-2188, Japan
²  Department of Physics and Applied Physics, Waseda University - Tokyo 169-8555, Japan
³  Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University Tokyo 192-0397, Japan
⁴  Department of Chemistry, National Taiwan University - Taipei 106, Taiwan

Corresponding author: sfujii@mst.nagaokaut.ac.jp

Received: 10 February 2010
Accepted: 15 June 2010

Abstract

We study the rheological properties of a thermotropic liquid crystal, 8CB, in the smectic phase close to the smectic-nematic (Sm-N) transition temperature. Three different regimes were identified in the flow curves at different temperatures: i) appearance of the yield stress at low stresses, ii) power law behavior at intermediate shear stresses, and iii) Newtonian at higher shear stresses. The vanishing of the yield stress at the Sm-N transition temperature is correlated with a rapid growth of focal conic domains. The constructed dynamic phase diagram exhibits the two different smectic phases together with the flow-induced Sm-N transition.