Lignin has been mass produced in the paper and pulp industry with about 50 million tons produced in 2013. However, of the 50 million tons, only 2 % was further refined for commercial use whereas the remaining 98 % was burned as low-value fuel. Ultimately, this untapped biomaterial can be used in polymeric blends with petroleum-derived synthetics to decrease costs and increase the environmental sustainability of the finished products. However, within the use of lignin, there have been notable problems in its processibility, which are attributed to its low molecular weight and structural irregularities.<br/><br/>Depending on the process of extraction, lignin types can have different chemical structures. These differences can affect the build-up of molecular weight and their rheology post polymerization. Both Kraft lignin and acid-hydrolyzed lignin were used to investigate the effect of –ene group (C=C) concentration on the polymerization of each lignin type. Solution viscosities of Kraft lignin dissolved in dimethyl sulfoxide (DMSO) increased as the weight percentage of free radical initiator reached 20 % of lignin. An elastic, DMSO insoluble polymer formed once initiator concentration reached 50 % of lignin. Further viscosity did not increase with initiator concentration for reactions involving acid-hydrolyzed lignin. NMR analysis showed distinct variation on specific peak ranges as noted in literature indicating structural changes.

Radical polymerization of lignin materials

2019 Fall National Meeting

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