Abstract
Solvolysis pulps (CWPs) were prepared from two species of softwoods using the cresol-water system. The crystallinity, degree of polymerization (DP) and α-cellulose content of the CWPs were measured to elucidate the influence of delignification with sodium chlorite on the physicochemical properties of CWP. X-ray diffractograms revealed that the crystalline regions of CWPs maintained the cellulose I structure. An increase in the crystallinity of CWPs with increasing delignification was observed by X-ray diffraction and 13C-CP/MAS NMR studies. A further delignification brought about a slight destruction of the crystalline regions. DP was decreased significantly at the initial stage of the delignification and then was gradually decreased. α-Cellulose content of the delignified pulp was also reduced slightly at the final stage. A similar tendency was observed for commercial unbleached kraft pulp and sulfite pulp which underwent the same treatment. These results suggested that the amorphous regions of unbleached pulps were destroyed during the delignification treatment due to the acidic medium follwed by collapse of the crystalline regions.
