Influences of molecular weight and thermal history on partial melting of polyethylene: Existence of non-lamellar crystallite

The effects of molecular weight and thermal history on the partial melting of polyethylene (PE) were investigated by in-situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. In the partial melting process, both surface melting and melting of small lamellae were...

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Bibliographic Details
Published in:Polymer (Guilford) 2020-12, Vol.211, p.123096, Article 123096
Main Authors: Rungswang, Wonchalerm, Jarumaneeroj, Chatchai, Parawan, Thawesak, Jirasukho, Prapasinee, Juabrum, Sawitree, Soontaranon, Siriwat, Rugmai, Supagorn
Format: Article
Language:English
Subjects:
Crystal structure
Crystallinity
Crystallites
Crystals
Lamellae
Lamellar structure
Low temperature
Melting
Molecular weight
Partial melting
Polyethylene
Polyethylenes
Small angle X ray scattering
X-ray diffraction
X-ray scattering
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Summary:The effects of molecular weight and thermal history on the partial melting of polyethylene (PE) were investigated by in-situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. In the partial melting process, both surface melting and melting of small lamellae were found to play prominent roles. However, in some cases that could not be explained by these mechanisms, the concept of “non-lamellar crystalline” (NLC) was proposed. We argue that melting of the NLC domains can also contribute to the partial melting, especially at low temperatures. The event would decrease the crystallinity but does not perturb the lamellar structure, which are not seen in surface melting and melting of small lamellae. Upon further heating, structural changes, including the extension of lamellar length and reduction of lamellar width, were also observed. The experimental results in the temperature range dominated by the surface melting mechanism could be described by the model proposed by Albrecht and Strobl. [Display omitted] •Molecular weight and thermal history play the important role on partial melting process.•Non-lamellar crystallite (NLC) domain is proposed, for the first time, to explain the partial melting process, especially at low temperature.•Beside the thinning of the lamellar thickness, the lamellar width becomes narrower during the lamellar melting process.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2020.123096