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Amorphous state transitions in butadiene–acrylonitrile copolymers
Author(s) -
Geiszler W. A.,
Koutsky J. A.,
Dibenedetto A. T.
Publication year - 1970
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.1970.070140110
Subject(s) - copolymer , glass transition , polybutadiene , acrylonitrile , crystallinity , materials science , amorphous solid , polymer chemistry , endothermic process , atmospheric temperature range , polymer , thermodynamics , composite material , chemistry , organic chemistry , physics , adsorption
Differential thermal analysis, creep measurements, and gas permeation rates are used to confirm the existence of a transition zone in three butadiene acrylonitrile copolymers in a temperature region that starts at roughly 15° to 25°C above the main glass transition temperatures of the copolymers and extends over a broad temperature range. The change appears to be slightly endothermic and softens the copolymers upon heating. It is speculated that the copolymers are in a mesomorphic state above their main glass temperature in which there is either a degree of ordering or a low‐grade crystallinity of polybutadiene units along the copolymer chains. It is not until the copolymers are 50° to 75°C above their main glass temperature that they become truly amorphous.