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Influence of change in ether structure on the low temperature dielectric relaxation of some poly(ether imide)
Author(s) -
Eastmond Geoffrey C.,
Paprotny Jerzy,
Pethrick Richard A.,
SantamariaMendia Fernan
Publication year - 2014
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.41191
Subject(s) - imide , dielectric , polymer , relaxation (psychology) , ether , glass transition , materials science , permittivity , activation energy , steric effects , dipole , polymer chemistry , chemical physics , chemistry , organic chemistry , composite material , psychology , social psychology , optoelectronics
Broad band dielectric relaxation spectra are reported on a range of polymers created by varying the ether segment in a series of poly(ether imide)s. Changes in the structure allow the effects of steric constraints on the local conformational dynamics of the polymer chain to be explored. These changes have a significant effect on the glass transition temperatures of these polymers which range from 245 to over 420°C. In contrast, the low temperature dielectric relaxation behavior of these polymers is very similar and is attributed to cooperative local oscillatory—librational motions. Changes in the stereochemistry effect the amplitude, activation energy for the relaxation process, the packing chain density, and values of the high frequency limiting permittivity, ε ∞ ′. This latter parameter is sensitive to the extent of dipole induced dipole and π‐π electron interactions and is influenced by the packing density. The magnitude of ε ∞ ′ is a very important parameter in determining the suitability of poly(imide)s for electrical applications. The magnitude of ε ∞ ′ increases with the density; however, deviations from this general trend are observed when large nonpolar groups inhibit the interaction of neighboring chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 41191.