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The use of thermally modified wood results in a significantly extended lifespan compared with untreated wood, with minimal maintenance requirements, thereby reducing the carbon footprint. This study examines the impact of varying modification temperatures (160, 180, and 210 \u00b0C) on the lignin of spruce wood using the ThermoWood process and following the accelerated aging of thermally modified wood. Wet chemistry methods, including nitrobenzene oxidation (NBO), size exclusion chromatography (SEC), thermogravimetry (TG), differential thermogravimetry (DTG), and Fourier transform infrared spectroscopy (FTIR), were employed to investigate the alterations in lignin. At lower modification temperatures, the predominant reaction is the degradation of lignin, which results in a reduction in the molecular weight and an enhanced yield of NBO (vanillin and vanillic acid) products. At elevated temperatures, condensation and repolymerization reactions become the dominant processes, increasing these traits. The lignin content of aged wood is higher than that of thermally modified wood, which has a lower molecular weight and a lower decomposition temperature. The results demonstrate that lignin isolated from thermally modified wood at the end of its life cycle is a promising feedstock for carbon-based materials and the production of a variety of aromatic monomers, including phenols, aromatic aldehydes and acids, and benzene derivatives.<\/jats:p>","DOI":"10.3390\/polym17020238","type":"journal-article","created":{"date-parts":[[2025,1,20]],"date-time":"2025-01-20T07:47:37Z","timestamp":1737359257000},"page":"238","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Impact of Thermal Treatment and Aging on Lignin Properties in Spruce Wood: Pathways to Value-Added Applications"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8989-0833","authenticated-orcid":false,"given":"Franti\u0161ek","family":"Ka\u010d\u00edk","sequence":"first","affiliation":[{"name":"Department of Chemistry and Chemical Technology, Faculty of Wood Sciences and Technology, Technical University in Zvolen, 96001 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eva","family":"V\u00fdbohov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Chemical Technology, Faculty of Wood Sciences and Technology, Technical University in Zvolen, 96001 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6032-7289","authenticated-orcid":false,"given":"Tereza","family":"Jurczykov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kam\u00fdck\u00e1 129, 16000 Prague, Czech Republic"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3094-7476","authenticated-orcid":false,"given":"Adriana","family":"E\u0161tokov\u00e1","sequence":"additional","affiliation":[{"name":"Institute for Sustainable and Circular Construction, Faculty of Civil Engineering, Technical University of Ko\u0161ice, Vysoko\u0161kolsk\u00e1 4, 04200 Ko\u0161ice, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-9315-141X","authenticated-orcid":false,"given":"Elena","family":"Kme\u0165ov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Fire Protection, Faculty of Wood Sciences and Technology, Technical University in Zvolen, 96001 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Danica","family":"Ka\u010d\u00edkov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Fire Protection, Faculty of Wood Sciences and Technology, Technical University in Zvolen, 96001 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,1,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"895","DOI":"10.3832\/ifor2380-010","article-title":"Wood modification technologies\u2014A review","volume":"10","author":"Sandberg","year":"2017","journal-title":"iFor.-Biogeosci. 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