Thermal diffusivity and the conformal transformation on nematic liquid crystals.
In this paper, we will study theoretically and experimentally the anisotropy of the thermal diffusivity in nematic liquid crystals. We will show that the Baalss-Hess conformal transformation [D. Baalss and S. Hess, Phys. Rev. Lett. 57, 86 (1986)], can be used to obtain a free of adjustable parameters equation that describes the anisotropy of the heat diffusion in these materials. The results of this theory will be compared with experimental data. This study will partially confirm the widely known experimental evidences that indicate that the thermal diffusivity is larger in the director direction than in the one perpendicular to it. For calamitic nematic phases this is true; for discotic nematic ones the reverse situation would be found; the diffusivity would become larger in the direction perpendicular to the director. We will also present experimental data supporting this theoretical prediction. The data comprehend the calamitic and discotic nematic lyotropic phases and a nematic thermotropic phase.
Departamento de Física, Universidade Estadual de Londrina, Campus Universitário, 86051-990-Londrina (PR), Brazil. simoes@uel.br
M
M
Simões
A J
AJ
Palangana
A
A
Steudel
N M
NM
Kimura
S L
SL
Gómez