EFFECT OF LIGNIN DERIVATIVES ON THE MACROMOLECULAR PROPERTIES OF LIGNIN IN NSSC COOKING

The changes in molecular-weight distribution, average molecular weight, degree of polymerization, degree of branching and crosslinking density of residual and dissolved lignins from NSSC pulping of beech wood with the lignin derivative as addtive were examined, and compared with those from cooking with antraquinone and without additives. Addition of oxidized lignin to pulping liquor brings about a moderate decrease in the branching degree, cross-linking density and average molecular-weight of the residual lignin and significantly decrease the relative proportion of the high-molecular-weight fraction of both dissolved and residual lignins. Comparison with AQ-NSSC pulping indicates that lignin derivatives stabilized the lignin macromolecule towards condensation reactions similarly as antraquinone. © 1990, Walter de Gruyter. All rights reserved.