Preparation of lignosulfonates from kraft lignin by sulfonation

초록

In order to apply technical lignins to functional biomaterials, lignosulfonates (LSs) were prepared from fractionated lignin by sulfonation with different amounts of sulfuric acid and their physical, chemical and thermal properties were analyzed to determine the effect of sulfonic acid content in lignosulfonates. It was confirmed that sulfonic acid group was introduced at a carbon position of the lignin side chain structure in lignosulfonate. In addition, as the amount of sulfuric acid was increased up to 7.5%, the content of SO₃H increased up to 0.732 mmol/g. Similarly, as the SO₃H content increased, the water solubility was greatly improved and the molecular weight was slightly increased. The thermal stability of LSs increased as the content of SO₃H increased, but the maximum decomposition temperature became lower and the glass transition temperature was not significantly different because the thermal decomposition in the sulfonic acid group was lowered around 300°C, which influenced the thermal properties of LSs. © 2019 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.

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