Rheological characterisation of a liquid-crystalline diol and its dependence with an applied electric field

In the present work the rheological characterisation (steady-state and oscillatory data) of a non-chiral low molecular weight liquid-crystalline diol (denoted as HBP 6/6) exhibiting the nematic and smectic phases over a broad temperature range is presented. A non-Newtonian flow behaviour was found. This result, together with the progressive increase of the viscosity observed near the nematic-isotropic transition, suggests that the material behaves like a polymer, due to hydrogen bonding. The effect of an electric field applied normal to the flow direction, on the steady state in the nematic phase, was established. An electrorheological effect shows up, as an enhancement of the apparent viscosity, due to the positive dielectric anisotropy of this material. It was found that the increase of the apparent viscosity scales linearly with the applied field strength.