Viscosity peaks at the cholesteric-isotropic phase transitions.
In this work, the effective viscosity of the cholesteryl myristate and cholesteryl nonanoate liquid crystals is studied as a function of temperature at the region of their cholesteric-to-isotropic phase transition, where blue phases are found. Using a change of scale it is shown that the viscosity peaks that characterize these phase transitions are shape invariant, which suggests that large-scale fluctuations on the two-point correlation function give an important contribution to the observed viscosity. The consequences of this fact are investigated and, from the experimental data, the critical exponents associated with the diverging two-point correlation function are calculated. The results found for both compounds are essentially the same, being also in good agreement with the known values of the corresponding critical exponents of nematic-isotropic phase transition.
Simões
M
M
Departamento de Física, Universidade Estadual de Londrina, Campus Universitário, 86051-990 Londrina (PR), Brazil. simoes@uel.br
Palangana
A J
AJ
Sampaio
A R
AR
de Campos
A
A
Yamaguti
K E
KE