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Molecular motions in poly(vinyl acetate) revisited. A thermally stimulated current study
Author(s) -
Dias Ana B.,
Correia Natália T.,
MouraRamos Joaquim J.,
Fernandes Anabela C.
Publication year - 1994
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1994.210330309
Subject(s) - vinyl acetate , glass transition , relaxation (psychology) , dipole , polymer chemistry , materials science , thermodynamics , work (physics) , polymer , chemistry , nuclear magnetic resonance , organic chemistry , physics , psychology , social psychology , copolymer
The dipolar relaxation mechanisms in poly(vinyl acetate) have been studied in detail using the technique of thermally stimulated currents. The papers published in the literature about this subject are very contradictory, particularly with respect to the assignment of the observed discharges to the corresponding motions at the molecular level. This work aims at clarifying these problems. We detected and characterised three different relaxation mechanisms: (1) a low temperature one (around −140°C) which was attributed to local internal rotations in the acetate side‐groups; (2) a relaxation whose maximum occurs at 42°C, which corresponds to the glass transition relaxation, and shows a compensation behaviour; (3) an upper glass transition relaxation whose maximum appears at 87°C and was attributed to a liquid‐liquid transition. These assignments have been made on the basis of the analysis of the behaviour of the samples when submitted to different thermal and electrical treatments.