Lignin is nature’s most abundant aromatic polymer and it has high potentials as feedstock for material applications. However, lignin is inherently heterogeneous since lignin is a composition of molecules that differ in molar mass, monomeric unit composition, number of functional groups, amount and composition of bound carbohydrates as well as branching. Improving lignin homogeneity is essential to improve its performance in material applications. In this presentation, we present that aqueous solvent fractionation procedure is potential technology to distribute lignin into fractions with more homogeneous structure and composition. In this process, lignin is first dissolved in aqueous organic solvent (e.g. acetone, ethanol) followed by selective precipitation of lignin fractions by increasing water concentration of the solution. The produced lignin fractions differed both in chemical composition and in structure. The precipitated lignin fractions were practically free from impurities (carbohydrates or ash) which enriched both in the insoluble and highly soluble fractions. The most soluble fraction had the lowest molar mass and it possessed more phenolic and carboxylic acid moieties than other lignin fractions. The performance of the produced lignin fractions as reinforcing fillers or antioxidants in composite materials and as phenol-replacing component in phenol formaldehyde resin is discussed.

Improving lignin homogeneity by aqueous solvent fractionation

255th National Meeting (2018)

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