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Comparison of the molecular properties and morphology of polypropylenes irradiated under different atmospheres and after annealing
Author(s) -
Krause Beate,
Häußler Liane,
Voigt Dieter
Publication year - 2006
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.23384
Subject(s) - polypropylene , annealing (glass) , differential scanning calorimetry , materials science , radical , crystallization , irradiation , molar mass , polymer chemistry , oxygen , nitrogen , scanning electron microscope , branching (polymer chemistry) , analytical chemistry (journal) , chemical engineering , chemistry , polymer , composite material , organic chemistry , thermodynamics , physics , nuclear physics , engineering
Electron‐beam irradiation, a well‐known way of generating long‐chain branching, was used to modify polypropylene. Samples were investigated with differential scanning calorimetry, polarized light microscopy, and size exclusion chromatography. Independently of the atmosphere, postannealing led to the deactivation of residual radicals and to the reduction of the nucleus density. In comparison with the initial polypropylene, the crystallization temperatures increased for nonannealed samples but decreased for annealed samples. Stable products were obtained only by irradiation in nitrogen followed by annealing. A reaction including free radicals with oxygen in the ambient atmosphere led to increasing molar mass degradation and the formation of long‐chain branching after storage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 634–639, 2006