New Method for Determining the Degree of Cellulose I Crystallinity by Means of FT Raman Spectroscopy

Abstract A Raman crystallinity index – XcRaman – characterizing the degree of crystallinity of partially crystalline cellulose I samples was created, utilizing the crystallinity dependence of CH2 bending modes. For calibration, physical mixtures containing different mass fractions of crystalline cellulose I and its amorphous form were prepared. Crystallinities from 0 to 60% were generated. Relative intensity ratios of the Raman lines I <img src="/fulltext-image.asp?format=htmlnonpaginated&src=M641P08574033PW9_html\10570_2004_Article_3885_TeX2GIFIEq1.gif" border="0" alt="$$_{1481 {cm^-1}}$$" /> and I <img src="/fulltext-image.asp?format=htmlnonpaginated&src=M641P08574033PW9_html\10570_2004_Article_3885_TeX2GIFIEq2.gif" border="0" alt="$$_{1462 {cm^-1}}$$" /> characterizing crystalline and amorphous parts of cellulose I correlated linearly with the mass fraction of crystalline cellulose I of the mixtures. XcRaman values of microcrystalline celluloses of different origins and varying degree of crystallinity correlated reasonably with results obtained from NMR spectroscopy (XcNMR values).