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Induced crystallization of EVA having various VA contents by compressed CO 2
Author(s) -
Shieh YeongTarng,
Lin YenGu
Publication year - 2002
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.11575
Subject(s) - crystallization , crystallinity , differential scanning calorimetry , vinyl acetate , materials science , sorption , endothermic process , polymer chemistry , ethylene vinyl acetate , chemical engineering , copolymer , polyethylene , composite material , chemistry , thermodynamics , organic chemistry , polymer , adsorption , physics , engineering
The crystallization induced by compressed CO 2 was investigated for rubbery ethylene‐vinyl acetate copolymer (EVA) containing various amounts of vinyl acetate (VA). The induction of crystallization was demonstrated by appearance of shoulder‐like differential scanning calorimetry (DSC) endotherms at temperatures lower than T m of polyethylene segments of EVA after CO 2 treatments. The intensity of the endothermic shoulders and the degree of crystallinity increased with increasing VA content, suggesting that the interaction of CO 2 ‐carbonyl groups governed the induction of crystallization of EVA upon CO 2 treatment. The interaction of CO 2 ‐carbonyl group was found to decrease with increasing temperature as demonstrated by the decreased crystallization enhancement for 37°C as compared with that for 32°C. The enhancement of crystallization did not monotonically increase with increasing CO 2 pressure, resulting from the interplay of thermodynamic and kinetic driving forces, both being associated with the CO 2 pressure and thus the sorption concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1144–1151, 2003