Correlations of Apparent Cellulose Crystallinity Determined by XRD, NMR, IR, Raman, and SFG Methods

David Johnson, Christopher Lee, Kevin Dazen, Kabindra Kafle, Andrew Moore, Sunkyu Park, Seong Kim

Research output: Contribution to conferencePaperpeer-review

34 Scopus Citations

Abstract

Although the cellulose crystallinity index (CI) is used widely, its limitations have not been adequately described. In this study, the CI values of a set of reference samples were determined from X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and infrared (IR), Raman, and vibrational sum frequency generation (SFG) spectroscopies. The intensities of certain crystalline peaks in IR, Raman, and SFG spectra positively correlated with the amount of crystalline cellulose in the sample, but the correlation with XRD was nonlinear as a result of fundamental differences in detection sensitivity to crystalline cellulose and improper baseline corrections for amorphous contributions. It is demonstrated that the intensity and shape of the XRD signal is affected by both the amount of crystalline cellulose and crystal size, which makes XRD analysis complicated. It is clear that the methods investigated show the same qualitative trends for samples, but the absolute CI values differ depending on the determination method. This clearly indicates that the CI, as estimated by different methods, is not an absolute value and that for a given set of samples the CI values can be compared only as a qualitative measure.

Original languageAmerican English
Pages115-131
Number of pages17
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© Springer International Publishing Switzerland 2015.

NREL Publication Number

  • NREL/CH-2700-70388

Keywords

  • Crystallinity index
  • Infrared spectroscopy
  • Nuclear magnetic resonance
  • Raman spectroscopy
  • Sum frequency generation spectroscopy
  • Wood pulp
  • X-ray diffraction

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