Figure 3.

Residual lignin structures in pulp fibers—results of the re-attachment of lignin to carbohydrates in NSSC pulps from Red Alder and Douglas Fir wood (on the basis of ¼ to 8 ½ h of cooking times and representing pulp yields of between 59 and 90%; the recovered, purified and analyzed pulp fiber lignins represented between 6 and 65% of the total lignin content of wood; for more information, see Glasser and Barnett, 1979a): (A) Interunit-linkage distribution; (B) Functional group distribution (total, aliphatic, phenolic, and sulfonate groups); (C) nature of association with carbohydrates (cellulosic vs. non-cellulosic sugar content in % of total carbohydrate content; pulp yield and cooking times indicated on each line; for more information, see Glasser and Barnett, 1979a,b; Glasser and Morohoshi, 1979; Glasser et al., 1979, 1982). (D) Proposed mechanism (Glasser, 1981) of the reaction leading to a restored lignin-carbohydrate bond as revealed by Ohara et al. (1980) on the basis of model compound studies.