A Comparative Study of the Viscosity Coefficients of Some Nematic Liquid Crystalss

Wiley - Tập 85 Số 8 - Trang 784-789 - 1981
H. Kneppe1, F. Schneider1, Naresh Sharma2,1
1Physikalische Chemie der Universität Siegen
2Department of Chemistry, University of Jammu, Jammu Tawi-180001, India.

Tóm tắt

AbstractThe viscosity coefficients η1, η2, η3 and η12 of 4‐n‐pentyl‐4'‐cyanobiphenyl, 4‐n‐octyl‐4'‐cyanobiphenyl, 4‐methoxy‐4'‐n‐butylazoxybenzene and an aromatic ester mixture were determined in the nematic phase region. Except for 4‐n‐octyl‐4'‐cyanobiphenyl, the viscosity coefficients of the liquid crystals show the following properties: 1) Three of the viscosity coefficients are related by an equation of the form Σ Aiηi = 0, in which the corresponding constants Ai are very similar for the different liquid crystals. 2) The equation ηi =aijηj + bij is valid with the exception of the neighbourhood of the clearing point. 3) The reduced viscosity coefficients 3ηi/(η1 + η2 + η3) of the different liquid crystals exhibit a very similar dependence on the reduced temperature and a nearly linear dependence on the degree of order. The viscosity coefficients η2 and η12 of 4‐n‐octyl‐4' ‐cyanobiphenyl show a divergence at the transition to the smectic phase, whereas η1 and η3 show the normal temperature dependence.

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Wiley

Tập 85 Số 8

784-789

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