Water-Related Properties of Wood after Thermal Modification in Closed Process under Pressure in Nitrogen
Author:
Sosins Guntis1, Grinins Juris1ORCID, Brazdausks Prans1, Zicans Janis2
Affiliation:
1. Latvian State Institute of Wood Chemistry, 27 Dzerbenes Street, LV-1006 Riga, Latvia 2. Institute of Polymer Materials, Faculty of Materials Science and Applied Chemistry, Riga Technical University, 3/7 Paula Valdena Street, LV-1048 Riga, Latvia
Abstract
Silver birch (Betula pendula) and Scots pine (Pinus sylvestris) wood boards (1000 × 100 × 25 mm) were thermally modified in a 340 L pilot-scale device in nitrogen with a special focus on increasing dimensional stability and reducing hydrophilicity. The research expands our understanding of the TM process in a closed system under pressure of nitrogen and its impact on the water absorption capabilities of wood. Several thermal modification (TM) parameters were tested, including temperature (160–180 °C), maximum temperature duration (30–180 min), and TM chamber initial pressure (3–6 bar). TM wood dimensional changes, mass loss (ML), equilibrium moisture content (EMC), and anti-swelling efficiency (ASE) were determined to characterize the TM process intensity and evaluate the hydrophilicity. Birch wood exhibited a higher ML (5.9%–12%) than pine wood (2.6%–9%) after TM. TM caused a shrinkage in the tangential, radial, and total volume of both wood species. The TM birch wood ASE values varied from 22% to 69%, while the pine wood ASE was 27% to 58%. The cell wall total water capacity (CWTWC) of TM wood was greatly reduced. The EMC and volumetric swelling (VS) of TM birch and pine wood were 29% to 67% lower, respectively, at all relative humidities (65, 75, and 95%).
Funder
Latvian State Institute of Wood Chemistry Bio-economy
Reference22 articles.
1. A Review of Wood Modification Globally–Updated Findings from COST FP1407;Jones;Interdiscip. Perspect. Built Environ.,2020 2. Jones, D., Sandberg, D., Goli, G., and Todaro, L. (2020). Wood Modification in Europe: A State-of-the-Art about Processes, Products and Applications, Firenze University Press. [1st ed.]. 3. Scheiding, W., Ala-Viikari, J., and Tetri, T. (2022, January 25). Thermal Wood Modification after 20 Years of Commercialization: An Overview and the ThermoWood® Story. Proceedings of the 10th European Conference on Wood Modification, Nancy, France. 4. Zelinka, S.L., Altgen, M., Emmerich, L., Guigo, N., Keplinger, T., Kymäläinen, M., Thybring, E.E., and Thygesen, L.G. (2022). Review of Wood Modification and Wood Functionalization Technologies. Forests, 13. 5. Wood Modification Technologies—A Review;Sandberg;iForest,2017
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