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Crystalline memory effects in isothermal crystallization of syndiotactic polypropylene
Author(s) -
Supaphol Pitt,
Spruiell Joseph E.
Publication year - 2000
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/(sici)1097-4628(20000118)75:3<337::aid-app1>3.0.co;2-4
Subject(s) - polypropylene , differential scanning calorimetry , tacticity , enthalpy of fusion , fusion , isothermal process , crystallization , materials science , melting point , impurity , polymer chemistry , melting temperature , chemical engineering , analytical chemistry (journal) , thermodynamics , chemistry , composite material , polymer , chromatography , polymerization , organic chemistry , physics , engineering , linguistics , philosophy
Isothermal crystallization behavior after partial or complete melting of syndiotactic polypropylene was investigated by differential scanning calorimetry (DSC). On partial melting, the total concentration of predetermined nuclei was found to decrease with increasing fusion temperature and increasing time period that the sample spent at a specific fusion temperature. A significant effect of the rate of heating to the fusion temperature was also observed. On complete melting, the total concentration of predetermined nuclei was found to approach a constant value, which is the concentration of infusible heterogeneous nuclei (e.g., impurities, catalyst residues) present originally in the sample. At a specific fusion temperature, the concentration of predetermined athermal nuclei was found to decrease exponentially with the time period spent in the melt. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 337–346, 2000