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Influence of the mesophase structure on the β‐relaxation in liquid crystalline poly(meth)acrylates
Author(s) -
Schönhals Andreas,
Wolff Dietmar,
Springer Jürgen
Publication year - 1996
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/(sici)1099-1581(199611)7:11<853::aid-pat593>3.0.co;2-5
Subject(s) - mesophase , materials science , meth , relaxation (psychology) , liquid crystal , polymer science , liquid crystalline , polymer chemistry , composite material , copolymer , acrylate , polymer , psychology , social psychology , optoelectronics
The dependence of the rotation of the mesogenic unit around its long axis (β‐relaxation) on the actual mesophase in liqid crystalline polymethacrylates and polyacrylates was studied by dielectric spectroscopy in the frequency range from 10 −2 Hz to 10 6 Hz and in a temperature range from 170 K to 430 K. As mesogenic units derivatives of (p‐alkoxy‐phenyl)‐benzoate were used where different mesophases were achieved by small variation of the mesogenic structure, the spacer length and the tail group of the mesogenic unit. For all samples the temperature dependence of the relaxation rate of the β‐relaxation can be described by an Arrhenius equation where both the pre‐exponential factor and the activation energy increase significantly with the order of the mesophase. To characterize the structure X‐ray measurements were also carried out. The mean lateral mesogenic distance was correlated directly with relaxational quantities.