Abstract
Thermally modified timber (TMT) reduces hygroscopicity, increases dimensional stability, and decay resistance. Although there is a substantial amount of research on heat-treated wood, investigations on the sensitivity of cell wall swelling behavior to water variation are limited. Therefore, this study focused on the swelling behavior of TMT from cellular and chemical perspectives. The effects of heat treatment on the hygroscopicity and swelling behavior of the wood cell walls were studied using dynamic vapor sorption and confocal laser scanning microscopy. Changes in the chemical composition and cellulose crystallinity were studied using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction. The results revealed that the hygroscopic swelling of latewood significantly decreased with increasing treatment temperature, reducing the anisotropy of the wood cell swelling. The hygroscopicity of wood was reduced by heat treatment, and a clear decrease in hysteresis was observed at elevated treatment temperatures. The FTIR spectra indicated that both hemicellulose and lignin were degraded. The crystallinity and lateral size of the cellulose increased after heat treatment. Similar changes in the chemical composition and crystallinity of cellulose were observed in the latewood and earlywood.
Funding source: Youth Program of National Natural Science Foundation of China
Award Identifier / Grant number: 31800478
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Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
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Research funding: This work was financed by a grant-in-aid for scientific research from the Youth Program of National Natural Science Foundation of China (no. 31800478).
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Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
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