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Determination of the content of extended chain segments in isotropic and uniaxially stretched polyethylenes by raman spectroscopy
Author(s) -
RodríguezCabello J. C.,
MartínMonge J.,
Lagarón J. M.,
Pastor J. M.
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19981201)199:12<2767::aid-macp2767>3.0.co;2-p
Subject(s) - raman spectroscopy , polymer chemistry , isotropy , materials science , polymer science , chain (unit) , composite material , chemical engineering , optics , physics , engineering , astronomy
The Raman spectrum of polyethylene is known to be mainly sensitive to the conformational state of the polymer chain. At room temperature, most of the vibrations of the polyethylene Raman spectrum are intrinsically reflecting only one‐dimensional order along the chain length. Based on the latter, we propose a straightforward quantitative procedure for the calculation of the content of extended (all‐ trans ) and non‐extended chain segments by using the CC asymmetric stretching, the CH 2 twisting and the CH 2 wagging vibrations. The applicability of this procedure is demonstrated by using a set of samples covering a wide range of densities which, in addition, were subjected to uniaxial stretching and annealing. The results suggest that a significant portion of extended chain segments is placed outside the crystalline domains. Besides, in stretched samples, an important increase in the extended chain segments content was found. This is likely caused by the presence of highly oriented chain segments in the non‐crystalline regions. These further disappeared as the stretched samples were annealed.