Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.21/5148
Título: Electrorheology study of a series of LC cyanobiphenyls: Experimental and theoretical treatment
Autor: Patrício, Pedro Manuel Alves
Leal, Catarina Marques Mendes Almeida da Rosa
Pinto, L.
Boto, A.
Cidade, M. T.
Palavras-chave: Liquid Crystals
Leslie-Ericksen Theory
Nematic Phase
Data: Jan-2012
Editora: Taylor & Francis
Citação: PATRÍCIO, P.; [et al] – Electrorheology study of a series of LC cyanobiphenyls: Experimental and theoretical treatment. Liquid Crystals. ISSN: 0267-8292. Vol. 39 (2012), pp. 25-37
Resumo: In this work we study the electro-rheological behaviour of a series of four liquid crystal (LC) cyanobiphenyls with a number of carbon atoms in the alkyl group, ranging from five to eight (5CB–8CB). We present the flow curves for different temperatures and under the influence of an external electric field, ranging from 0 to 3 kV/mm, and the viscosity as a function of the temperature, for the same values of electric field, obtained for different shear rates. Theoretical interpretation of the observed behaviours is proposed in the framework of the continuum theory of Leslie–Ericksen for low molecular weight nematic LCs. In our analysis, the director alignment angle is only a function of the ratio between the shear rate and the square of the electric field – boundary conditions are neglected. By fitting the theoretical model to the experimental data, we are able to determine some viscosity coefficients and the dielectric anisotropy as a function of temperature. To interpret the behaviour of the flow curves near the nematic–isotropic transitions, we apply the continuum theory of Olmsted–Goldbart, which extends the theory of Leslie–Ericksen to the case where the degree of alignment of the LC molecules can also vary.
Peer review: yes
URI: http://hdl.handle.net/10400.21/5148
DOI: 10.1080/02678292.2011.610471
ISSN: 0267-8292
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