Crystallization and melting of isotactic polypropylene crystallized from quiescent melt and stress‐induced localized melt. Issue 12 (8th April 2017)

• Record Type: Journal Article
• Authors: Lu, Ying; Wang, Yaotao; Chen, Ran; Men, Yongfeng
• Is Part Of: Journal of polymer science. Volume 55:Issue 12(2017)
• Page Start: 957
• Page End: 963
• Publication Date: 2017-04-08
• Subjects: crystallization -- isotactic polypropylene -- melting -- recrystallization -- small angle X‐ray scattering (SAXS); 547
• DOI: 10.1002/polb.24345
• Languages: English
• ISSNs: 0887-6266

Abstract

ABSTRACT: Temperature dependency of crystalline lamellar thickness during crystallization and subsequent melting in isotactic polypropylene crystallized from both quiescent molten state and stress‐induced localized melt was investigated using small angle X‐ray scattering technique. Both cases yield well‐defined crystallization lines where inverse lamellar thickness is linearly dependent on crystallization temperature with the stretching‐induced crystallization line shifted slightly to smaller thickness direction than the isothermal crystallization one indicating both crystallization processes being mediated a mesomorphic phase. However, crystallites obtained via different routes (quiescent melt or stress‐induced localized melt) show different melting behaviors. The one from isothermal crystallization melted directly without significant changing in lamellar thickness yielding well‐defined melting line whereas stress‐induced crystallites followed a recrystallization line. Such results can be associated with the different extent of stabilization of crystallites obtained through different crystallization routes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2017, 55, 957–963 Abstract : Stability of the crystallites in isotactic polypropylene was found to be route dependent with those crystallized from quiescent melt possessing much higher stability than those formed during stretching semicrystalline samples via a stress‐induced localized melting and recrystallization. The difference can be attributed to the restricted stabilization process after forming native crystallites in the case of stretching induced melting and recrystallization due to the rather hard surroundings of the localized melt.