Title: Primary and secondary crystallization in a homogeneous ethylene-1-octene copolymer: Crystallinity heterogeneity studied by SAXS
Authors: Goderis, Bart ×
Reynaers, Harry
Koch, MHJ #
Issue Date: Jan-2002
Publisher: Amer chemical soc
Series Title: Macromolecules vol:35 issue:15 pages:5840-5853
Abstract: The structural changes occurring in a 5.2 mol % 1-octene homogeneous ethylene-1-octene copolymer sample during a cooling and heating cycle at 10 degreesC/min are described in detail using DSC, AFM, SALLS, and synchrotron WAXD and SAXS. The DSC cooling curve exhibits two exothermic maxima where the high-temperature maximum marks out the temperature window associated with primary crystallization (spherulite nucleation and growth). The morphology after spherulite impingement is characterized by local differences in crystallinity. Secondary crystallization by lamellar insertion is fastest in the largest amorphous areas and results in a spatial homogenization of the crystallinity at a given temperature between the two DSC maxima. The small low-temperature DSC peak is associated with the nucleation of small or imperfect crystals in the confined spaces between existing crystals. During heating, regions with different degrees of crystallinity develop again, An evaluation method for SAXS linear correlation functions is introduced to handle crystallinity heterogeneity. The underlying, basic model is a pseudo-two-phase structure with part of the crystalline-amorphous interphase contributing to the WAXD and DSC crystallinity.
ISSN: 0024-9297
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Imaging and Photonics
Chemistry - miscellaneous
Polymer Chemistry and Materials
× corresponding author
# (joint) last author

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