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Molecular Orientation Distribution of Regenerated Cellulose Fibers Investigated with Polarized Raman Spectroscopy

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posted on 15.05.2019, 15:39 by Leo Svenningsson, Yuan-Chih Lin, Maths Karlsson, Anna Martinelli, Lars Nordstierna
The molecular orientation distribution of polymeric fibers influences physical properties. We present a novel method of analyzing polarized Raman experiments to determine molecular orientation, which is based on exchanging the Legendre polynomial approach with a wrapped Lorentzian function, as determined from a prescreening of X-ray scattering patterns. This method removes the need for performing right angle scattering experiments while avoiding common approximations. The molecular orientation of regenerated cellulose fibers, using the presented method, is shown to correlate well with X-ray scattering and an analogous experiment using solid-state NMR spectroscopy. Challenges of quantitatively measuring molecular anisotropy occur with semi-crystalline, partially modified, or composite materials. As such, a plethora of techniques, each with a unique chemical selectivity, is paramount for material characterization.