DETERMINATION OF CELLULOSE I-ALPHA AND I-BETA IN LIGNOCELLULOSIC MATERIALS

A novel method to estimate the relative amounts of cellulose I-alpha and I-beta in lignocellulosic materials has been developed. C-13-CP/MAS NMR spectra were recorded on 12 calibration samples containing cellulose of various degrees of crystallinity. Principal component analysis of the NMR data extracted qualitative information about the relative amounts of amorphous cellulose, cellulose I-alpha, and cellulose I-beta in the calibration samples. A quantitative partial least-squares (PLS) model was established between estimates of amorphicity index, cellulose I-alpha-content, and cellulose I-beta-content and the C-13-CP/MAS NMR data of the calibration samples. The cellulose I-alpha and I-beta content in some chemical and high-yield pulps was predicted from their NMR spectra by use of the PLS model. The existence of substantial amounts of cellulose I-alpha in the pulp samples was demonstrated with the PLS model.