Kraft lignin molecular weight

Source From Hardwood kraft lignin Molecular weight dependent structural properties and non-covalent interactions between constituent species, in M.S. Thesis University of Minnesota. 

Both the sulfite and alkaline (kraft) methods can be modified to produce high purity chemical ceUulose. These pulps, usuaUy in the form of "dissolving pulps," are not only mosdy free of lignin and hemiceUulose, but the molecular weight of the ceUulose is degraded. This increases solubUity in alkah and provides desired viscosity levels in solution. These dissolving pulps are used to make derivatives such as sodium ceUulose xanthate [9051 -13-2] via alkah ceUulose, and various esters and ethers (see Cellulose esters Cellulose ethers). 

Two Streptomyces strains, S. badius and S. viridosporus, were found to be able to grow on kraft lignin (In-dulin ATR) as sole carbon source. The resulting APPL (Acid Precipitable Polymeric Lignin) was characterized by FTIR and elemental analysis for C, H and N, and was found to contain proteins in addition to a relatively demethoxylated lignin component. The proteins were further characterized by amino acid analysis, while the lignin component was separated by solvent extraction and its molecular weight distribution determined by HPSEC. 

The presence of kraft lignin association was indicated at all alkalinities and all molecules participated. The association was strongly pH dependent and completely reversible. However, the extent of the association for the small molecules and the large molecules was different. The high molecular weight molecules show considerable association in the pH 13.5 to pH 12.0 range, with little or no further association at lower alkalinities. The small molecules showed no association above pH 13.0 and the major association was in the pH 13.0 to 11.0 region. Below 10.0 there was no further association. 

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