Fragility and Glass Transition Temperature in the Rheological Response of Azobenzene Copolymers

Two copolymers containing nonmesogenic methyl methacrylate (MMA) and nematogenic azobenzene methacrylate (MA4) side groups (30/70 and 40/60 copolymers) azobenzene were studied in the linear viscoelastic regime. The time-temperature superposition principle was found to hold over the whole investigate...

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Bibliographic Details
Published in:Molecular crystals and liquid crystals (Philadelphia, Pa. : 2003) Pa. : 2003), 2006-07, Vol.450 (1), p.173/[373]-182/[382]
Main Authors: Andreozzi, L., Faetti, M., Giordano, M., Zulli, F., Galli, G., Samaritani, S.
Format: Article
Language:English
Subjects:
azobenzene
liquid crystal polymer
nematic
rheology
shear viscosity
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Summary:Two copolymers containing nonmesogenic methyl methacrylate (MMA) and nematogenic azobenzene methacrylate (MA4) side groups (30/70 and 40/60 copolymers) azobenzene were studied in the linear viscoelastic regime. The time-temperature superposition principle was found to hold over the whole investigated temperature range, even across the nematic-isotropic transition in the 30/70 copolymer. Rheological steady state and oscillatory measurements were used to obtain the temperature dependence of the zero shear viscosity. The strength and dynamic fragility of these two copolymers were compared with those of the corresponding PMA4 and PMMA homopolymers, which pointed out the role of the structure of the main chain in dictating the relaxational dynamics.
ISSN:1542-1406
1563-5287
DOI:10.1080/15421400600588132