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Publicação
On row-structures in sheared polypropylene and a propylene–ethylene copolymer
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Orientador(es)
Resumo(s)
The crystallisation of polymers such as polyethylene or polypropylene from the melt is greatly influenced by the flow-thermal history prior to the crystallisation. We explore the influence of the chemical configuration of polypropylene based chains on the formation of row structures on crystallisation. We use a combination of in situ time resolved smallangle X-ray scattering, ex situ wide angle X-ray scattering with optical and scanning electron microscopy to show that row nuclei are formed in random copolymers of propylene with a limited amount of ethylene subjected to modest shear flow fields. We contrast observations performed using two homopolymers of isotactic polypropylene and one random copolymer of propylene and ethylene. We propose that it is not strictly necessary to argue that the row nuclei are already crystalline nor to invoke epitaxial crystallisation as the mechanism for the nucleation of lamellae, as similar structures can be formed on carbon nanotubes and fibrils of dibenzylidene sorbitol. The combination of microscopy and
scattering provides a powerful approach to investigating these phenomena, especially as
compared to either technique used in isolation.
Descrição
Palavras-chave
Polypropylene Copolymer Nucleation SEM (scanning electron microscopy) WAXS (wide-angle X-ray scattering) SAXS (small-angle X-ray scattering)
Contexto Educativo
Citação
Robert H. Olley, Geoffrey R. Mitchell, Yasmin Moghaddam, On row-structures in sheared polypropylene and a propylene–ethylene copolymer, European Polymer Journal, Volume 53, 2014, Pages 37-49, ISSN 0014-3057, https://doi.org/10.1016/j.eurpolymj.2014.01.010
Editora
Elsevier BV
Licença CC
Sem licença CC