Abstract:

Structural characterizations of four cellulose fractions isolated by alkaline hydrogen peroxide from defatting Mucuna sempervirens fiber were studied. With the increasing of fractional grade, weight-average molecular weight gradually decreased owing to the increase in splitting degree of cellulose molecular chain. Four cellulose fractions belong to cellulose Ⅰ. Except that there contained a little lignin and hemicellulose in the first fractional cellulose because there obviously appeared the absorbance spectra relative to lignin and hemicellulose in the FTIR pictures. However, there didn’t nearly contained lignin and hemicellulose in the second, third and fourth fractional cellulose because their purities were high above 97.0%. After fractionating, there happened some great changes for the structure of four cellulose fractions. That is, cellulose bundles became much shorter and much thinner from the first fractional cellulose to the fourth fractional cellulose. The crystalline degree of the first, second, third and fourth fractional cellulose increased in proper order, while the crystalline degree of first fractional cellulose was much lower.

Key words: Mucuna sempervirens, cellulose, fractional isolation, structural characteristic