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Effect of heat treatment on the dielectric relaxation of polyacrylonitrile. II. Heat treatment under vacuum and in air
Author(s) -
Gupta A. K.,
Singhal R. P.,
Maiti A. K.,
Agarwal V. K.
Publication year - 1982
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.1982.070271103
Subject(s) - polyacrylonitrile , dielectric , relaxation (psychology) , materials science , intermolecular force , diffraction , dipole , infrared , thermodynamics , infrared spectroscopy , analytical chemistry (journal) , molecule , chemistry , composite material , optics , organic chemistry , polymer , psychology , social psychology , physics , optoelectronics
Abstract Dielectric relaxation, infrared spectra, and X‐ray diffraction data of polyacrylonitrile (PAN) heat treated at 120°C in air and under vacuum and of the untreated PAN are reported. The heat treatment resulted in (1) lowering of dielectric constant increment, dielectric dissipation factor, and increase in relaxation temperature and glass transition temperature; (2) lowering of the intensity of CN stretching band in the infrared spectra; and (3) increase in degree of order of the X‐ray diffraction results. The changes produced by heat treatment under vacuum are found greater than those produced by heat treatment in air, which suggests that the observed effect is not caused by chemical changes in the PAN molecule under heat treatment. Interpretation of these results is attempted on the basis of the difference in the degree of bound nitrille group pairs (bound through intermolecular dipole–dipole interactions) in the structure of PAN heat treated under the different conditions.