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Thermorheological Simplicity and Fragility of Azobenzene Nematogenic Side‐Chain Polymers
Author(s) -
Andreozzi L.,
Autiero C.,
Faetti M.,
Galli G.,
Giordano M.,
Zulli F.
Publication year - 2008
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200850310
Subject(s) - fragility , viscoelasticity , liquid crystal , materials science , polymer , viscosity , thermodynamics , relaxation (psychology) , azobenzene , polymer chemistry , methyl methacrylate , isotropy , methacrylate , copolymer , optics , composite material , physics , psychology , social psychology , optoelectronics
Summary: The linear viscoelastic response of polymers from a nematogenic azobenzene methacrylate and its copolymers with nonmesogenic methyl methacrylate was studied. These samples showed thermorheological simplicity in the whole investigated temperature range, even across the nematic‐isotropic transition. The temperature dependence of the zero‐shear viscosity confirmed a thermorheologically simple behavior, which allowed interpretation of η ( T ) in the framework of free‐volume theory. The way the relaxation mechanisms tended to their asymptotic behavior was described in terms of fragility parameters, and a comparison of fragilities of the samples was carried out. The analysis of fragility and temperature dependence of viscosity provided better understanding of the way the architecture of these nematic polymers influences free‐volume quantities and determines relaxation mechanisms.