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Correlation of mechanical behaviors with crystalline phase and related cavitation in isotactic polypropylene
Author(s) -
Lv Ruihua,
Xu Wenfei,
Na Bing,
Yan Junzhang
Publication year - 2008
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.27971
Subject(s) - crystallinity , materials science , tacticity , differential scanning calorimetry , composite material , annealing (glass) , fracture toughness , toughness , polypropylene , polymer , polymerization , thermodynamics , physics
The β→α phase transformation during annealing of β‐nucleated isotactic polypropylene (iPP) at 160°C for 1 h has been confirmed by differential scanning calorimetry and X‐ray diffraction measurements. The α‐crystals and related crystallinity in the annealed samples result in higher yield stress and volume dilatation, indicated by the true stress–strain and volume strain analysis, respectively. Meanwhile, higher volume dilatation can find its origin in the lower network modulus in the annealed samples. The increasing yield stress and volume strain, related to the crystalline phase (including crystal form and crystallinity), furthermore, should be responsible for the significant deterioration of the fracture toughness in the annealed samples determined by the essential work of fracture tests. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008