Regularity modes in Raman spectra of polyolefins: Part II. Polyethylene and ethylene copolymers super([malt)

In this work, the thermal behavior of the regularity modes in Raman spectra of polyethylene with different densities and random ethylene/1-hexene copolymers with varying content of comonomer are studied. We demonstrate especially that the vibrational modes at 1062 and 2850 cm super([dlarr]1) are rel...

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Bibliographic Details
Published in:Vibrational spectroscopy 2016-05, Vol.84, p.139-145
Main Authors: Sagitova, Elena A, Donfack, Patrice, Nikolaeva, Gulnara Yu, Prokhorov, Kirill A, Zavgorodnev, Yury V, Pashinin, Pavel P, Ushakova, Tatiana M, Novokshonova, Lyudmila A, Starchak, Elena E, Guseva, Maria A, Gerasin, Viktor A, von der Kammer, Bernd, Materny, Arnulf
Format: Article
Language:English
Subjects:
Copolymers
Density
Ethylene
Evolution
Polyethylenes
Polyolefins
Raman spectra
Regularity
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Summary:In this work, the thermal behavior of the regularity modes in Raman spectra of polyethylene with different densities and random ethylene/1-hexene copolymers with varying content of comonomer are studied. We demonstrate especially that the vibrational modes at 1062 and 2850 cm super([dlarr]1) are related to a critical sequence length of trans-conformers of 6 square 8 CH sub(2) groups, while the modes at 1130, 1170, 1295, and 2883 cm super([dlarr]1) indicate a critical sequence length of trans-conformers of 18 CH sub(2) groups. Upon increasing the 1-hexene content in the ethylene/1-hexene copolymers, the evolution of the intensities of the Raman modes at 1062, 1130, 1170, 1295, and 1417 cm super([dlarr]1), normalized to the intensity of the band at 2850 cm super([dlarr]1), is similar to the evolution of the intensities of the same modes in the Raman spectra of low density polyethylene at increasing temperature. This observation however contrasts with that in the Raman spectra of polyethylenes with middle and high densities. We suppose that these results can be explained by similarities in the structure of non-crystalline areas of low density polyethylene and the ethylene/1-hexene copolymers, which contain significant amounts of short sequences of trans-conformers.
ISSN:0924-2031
DOI:10.1016/j.vibspec.2016.03.013