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Licensed Unlicensed Requires Authentication Published by De Gruyter March 16, 2022

Enhancing the mechanical properties and hydrophobicity of heat-treated wood by migrating and relocating sulfonated lignin

  • Yiqin Gao , Yuanyuan Li , Ruiqing Ren , Li Li , Jianmin Gao and Yao Chen EMAIL logo
From the journal Holzforschung


Heat-treated wood (HTW) has better dimensional stability but worse mechanical strength than untreated wood. This study aimed to overcome this shortcoming by sulfonating lignin in Balfour spruce (Picea likiangensis var. balfouriana) wood with sulfurous acid and Na2SO3 followed by heat treatment. The mass loss of as-prepared HTW decreased while the crystallinity index increased slightly compared with those of HTW without sulfonation pretreatment. The cellulose structure of the as-prepared HTW was not damaged by the sulfonation pretreatment. The as-prepared HTW showed a higher MOE, MOR, and compressive strength (CS) of 34, 32, and 22%, respectively, compared with the HTW without sulfonation treatment. The improved mechanical properties were attributed to the increase of the relative mass fraction of lignin in the secondary walls of wood, as sulfonated lignin could migrate with water from the compound middle lamellae into the secondary wall under the combined driving forces of a concentration difference and steam pressure. These findings provide a way to enhance the mechanical properties of HTW while gaining better hydrophobicity.

Corresponding author: Yao Chen, Key Laboratory of Wooden Material Science and Application (Ministry of Education), Beijing Forestry University, Beijing 100083, People’s Republic of China, E-mail:

Funding source: National Natural Science Foundation of China

Award Identifier / Grant number: 31400498

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: None declared.

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.


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Received: 2021-10-09
Accepted: 2022-02-16
Published Online: 2022-03-16
Published in Print: 2022-07-26

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