University of Oulu

Cai, C., Javed, M.A., Komulainen, S. et al. Effect of natural weathering on water absorption and pore size distribution in thermally modified wood determined by nuclear magnetic resonance. Cellulose 27, 4235–4247 (2020).

Effect of natural weathering on water absorption and pore size distribution in thermally modified wood determined by nuclear magnetic resonance

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Author: Cai, Chenyang1; Javed, Muhammad Asadullah2; Komulainen, Sanna3;
Organizations: 1School of Forest Sciences, University of Eastern Finland, Joensuu, Finland
2Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
3NMR Research Unit, University of Oulu, Oulu, Finland
4Natural Resources Institute Finland, Joensuu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.2 MB)
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Language: English
Published: Springer Nature, 2020
Publish Date: 2020-04-30


Thermally modified wood (TMW) is widely used in outdoor applications due to its advanced properties towards weathering stresses. Although the structure changes of TMW from weather factors have been reported, investigation of the quantitative analysis of water states and cell wall structure of TMW after weathering is limited. In this work, the amount of bound water, fiber saturation point (FSP), cell wall pores, and free water distribution of thermally modified Scots pine, Norway spruce, and European ash were measured before and after a 2-year natural weathering via NMR relaxometry, cryoporometry, and magnetic resonance imaging. The results show that weathering increased T₂ relaxation time of lumens, indicating the degradation of tracheids and vessels, especially in TMW compared to unmodified wood. The amounts of bound water, FSP value, and cell wall pores were increased after weathering; however, an increase in thermal modification intensity resulted in lower FSP and limited the increase in number of pores. In summary, TMW showed better performance than unmodified wood after weathering.

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Series: Cellulose
ISSN: 0969-0239
ISSN-E: 1572-882X
ISSN-L: 0969-0239
Volume: 27
Pages: 4235 - 4247
DOI: 10.1007/s10570-020-03093-x
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: Open access funding provided by Natural Resources Institute Finland (LUKE). The authors wish to present sincere thanks to the International ThermoWood Association and Teollisuusneuvos Heikki Väänänen’s Fund for co-funding the project. V-V.Telkki thanks the European Research Council (ERC) under Horizon 2020 (H2020/2018-2022/ERC Grant Agreement No. 772110), Academy of Finland (Grants #289649, 294027 and 319216), the Kvantum institute (University of Oulu) and the CA15209 COST action (EURELAX) for financial support.
EU Grant Number: (772110) UFLNMR - Ultrafast Laplace NMR
Academy of Finland Grant Number: 289649
Detailed Information: 289649 (Academy of Finland Funding decision)
294027 (Academy of Finland Funding decision)
319216 (Academy of Finland Funding decision)
Copyright information: © The Author(s) 2020. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit