Lignin makes up about 25% of wood, binding wood cells together and providing natural resistance to fungal decay. However, in paper production lignin is removed and incinerated. Despite its abundance, the inherent structural and chemical heterogeneity of lignin has, until now, complicated its commercial use. Furthermore, the utility of lignin dissolved in common solvents such as alcohols is challenged by rapid agglomeration leading to precipitation.
Because of the inherent protective qualities of lignin, embedding more lignin into wood has long been explored. Typically, studies have impregnated wood with lignin solubilized in various alcohols in concentrations less than 2 wt% (Borrega 2022, Chrikova et al. 2011, dos Santos et al. 2012, Gordobil et al. 2017, Herrera et al. 2023, Sanson et al. 2022). However, the discovery at the University of Copenhagen of how to make stable, highly-concentrated lignin solutions in simple mixtures of water and alcohols (Orozco 2022, Simonsen et al. 2024a,b), naturally lead to the question of whether these novel solutions could be used for wood impregnation.
This study presents some of the results from a larger experimental campaign where concentrated lignin solutions of various types were used for wood impregnation (Thybring et al. 2024). Surprisingly high mass gains were observed after impregnation – and even after leaching in water – resulting the term “hyperlignification” being coined.
Keywords: hyperlignification, wood protection, lignin
Authors
Kosma J. Celmer
University of Copenhagen, Denmark
Andrea Ponzecchi
University of Copenhagen, Denmark
Tor I. Simonsen
University of Copenhagen, Denmark
Sune T. Thomsen
University of Copenhagen, Denmark
Emil E. Thybring
University of Copenhagen, Denmark
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