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The crystallization and melting of linear polyethylene studied by temperature‐modulated SAXS and WAXD
Author(s) -
Goderis Bart,
Reynaers Harry,
Koch Michel H.J.
Publication year - 2002
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200290021
Subject(s) - crystallization , materials science , small angle x ray scattering , crystallite , isothermal process , polyethylene , annealing (glass) , crystal (programming language) , crystallography , linear low density polyethylene , analytical chemistry (journal) , thermodynamics , composite material , scattering , chemistry , optics , chromatography , metallurgy , physics , computer science , programming language
Temperature‐reversible and ‐irreversible morphological events could be separated in the case of linear polyethylene during quasi‐isothermal crystallization by using simultaneous temperature‐modulated synchrotron SAXS and WAXD. Crystallization and subsequent annealing was followed at 126 °C for 90 min while applying a temperature modulation with an amplitude of 1 °C and a period of 2 min. The crystal growth rate associated with the irreversible part of the crystallization decreases with increasing temperature in a cycle. The crystalline lamellae irreversibly thicken with time. The actual crystallite thickness, however, exhibits a superimposed modulation out of phase with that of the temperature modulation. Melting was studied during heating at 1 °C/min after cooling at 10 °C/min. A temperature modulation was superimposed with an amplitude of 2 °C and a period of 3 min. Once again temperature‐reversible crystal thickness changes and irreversible crystal thickening could be observed.