Viscosity and Functionality of Alkali and Organosolv Lignins

Lignin fractions at various stages of alkaline and organosolv digestions of Black Cottonwood were collected and their intrinsic viscosities were measured in a good solvent as well as under the theta-conditions. Using the theoretical relationships developed for branched polymers, these data confirm that the functionality of the cross-linked units in the lignin macromolecules is indeed four, in agreement with conclusions previously drawn from average molecular weight data