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Effect of annealing at temperature around glass transition temperature on molecular orientation and shrinkage of ethylene–vinyl alcohol copolymers
Author(s) -
Yoshida Hirohisa,
Tomizawa Kunio,
Kobayashi Yasuji
Publication year - 1979
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.1979.070241108
Subject(s) - annealing (glass) , shrinkage , crystallization , glass transition , materials science , vinyl alcohol , copolymer , ethylene , composite material , polymer chemistry , thermal , chemical engineering , chemistry , polymer , organic chemistry , thermodynamics , catalysis , engineering , physics
The effect of annealing on the molecular arrangement of ethylene–vinyl alcohol copolymers (EVA) was studied by optical methods. Drawn samples were annealed at temperatures near the glass transition temperature T g in two cases; the first case allowed thermal shrinkage and the second case did not. For annealing below T g , the hydroxyl groups were rearranged only to the stable position. Thermal shrinkage occurred by annealing at temperatures between T g and T g + 20–30 K. In the case of annealing at temperatures above T g + 30 K, thermal shrinkage and crystallization occurred. The crystallization by annealing made the drawn sample difficult to shrink.