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Influence of the molecular structure on the dynamics in poly(ester‐imide)s
Author(s) -
Abdallah Merenga,
Groothues Herbert,
Kremer Friedrich,
Kricheldorf Hans R.
Publication year - 1997
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1997.021980912
Subject(s) - arrhenius equation , imide , glass transition , polymer chemistry , chemistry , relaxation (psychology) , methylene , molecular dynamics , libration (molecule) , dielectric , activation energy , polymer , materials science , computational chemistry , organic chemistry , psychology , social psychology , point (geometry) , geometry , mathematics , optoelectronics
Dielectric spectroscopy in the frequency range from 0.1 to 10 5 Hz was employed to study the molecular dynamics of main‐chain poly(ester‐imide)s (PEIMs) with varying spacer lengths from 5 to 12 methylene units. For all samples three relaxation processes were observed. The β‐process shows an Arrhenius‐like temperature dependence with activation energies between 50 and 55 kJ/mol. This process is assigned to a local libration of the ester groups. The α * ‐process shows a WFL‐like temperature dependence. It is assigned to a main‐chain‐coupled motion of the mesogens around their short molecular axes. The α‐process also follows a WFL‐like temperature dependence. It is assigned to cooperative main‐chain motion of PEIM and it is correlated to the glass transition.