Modified Lignin Nanoparticles as Potential Conservation Materials for Waterlogged Archaeological Wood

Lignin is the most abundant component in archaeologicalwaterloggedwood, making it a potential consolidant with high compatibility forhistorical wood conservation. However, its consolidation effect islimited by its low penetration into the wood. In this study, modifiedlignin nanoparticles (LNPs) were proposed for the first time as conservationmaterials for waterlogged archaeological wood. Two modified LNPs wereprepared with low molecular weight, small size, and high solubilityin ethylene glycol (EG) for consolidating waterlogged wood samples.These nanoparticles, hydrophilic aminated LNPs (ALNPs) and hydrophobicesterified LNPs (MALNPs), greatly improved the consolidation effectof waterlogged wood samples compared to LNPs. This was demonstratedby measuring their physical properties, dimensional stability, andmechanical properties. The surface color change was almost withinthe acceptable range for the human eye. We also discussed two differentreinforcement mechanisms of ALNPs and MALNPs. ALNPs can form hydrogenbonds with hemicellulose/cellulose in the wood to strengthen the fragilewood cell wall, while MALNPs can fill the wood cell lumen to supportthe cell wall and prevent deformation during drying. Our work providesan approach of using biomaterials as consolidants for archaeologicalwaterlogged wood and expands the use of lignin in this field.

Automated summary

In this study, modified lignin nanoparticles (LNPs) were proposed as conservation materials for waterlogged archaeological wood for the first time. The consolidation effect of these modified LNPs was significantly improved compared to conventional LNPs, as demonstrated by the measurement of physical properties, dimensional stability, and mechanical properties. This research provides a new approach for using biomaterials as consolidants for archaeological waterlogged wood and expands the application of lignin in this field.