Investigating the Effect of Smoke Treatment on Hygroscopic Characteristics of Bamboo by FTIR and Raman Spectroscopy

Raviduth Ramful; Thefye P M Sunthar; Elia Marin; Wenliang Zhu; Giuseppe Pezzotti

doi:10.3390/ma15041544

Investigating the Effect of Smoke Treatment on Hygroscopic Characteristics of Bamboo by FTIR and Raman Spectroscopy

Materials (Basel). 2022 Feb 18;15(4):1544. doi: 10.3390/ma15041544.

Authors

Raviduth Ramful^{1

2}, Thefye P M Sunthar^{3

4}, Elia Marin^{3

5}, Wenliang Zhu³, Giuseppe Pezzotti^{3

4

5

6

7}

Affiliations

¹ Graduate School of Science and Technology, Kyoto Institute of Technology (KIT), Kyoto 606-8585, Japan.
² Mechanical and Production Engineering Department, Faculty of Engineering, University of Mauritius, Reduit 80837, Mauritius.
³ Ceramic Physics Laboratory, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
⁴ Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-0841, Japan.
⁵ Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
⁶ The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan.
⁷ Department of Orthopedic Surgery, Tokyo Medical University, Tokyo 105-8461, Japan.

Abstract

Treatment modification to improve the durability of bamboo against biotic and abiotic factors often results in adverse effects to its mechanical properties due to changes in hygroscopic characteristics. This study aims at exploring in more detail, the effect of treatment modification, in particular smoke treatment, on the hygroscopic nature of bamboo. In the first part of this study, changes to its chemical structure were investigated by Raman and Fourier-transform infrared (FTIR) spectroscopic techniques. From Raman analysis, specific bands attributed to lignin component in bamboo, namely at 1600 cm^-1 and 1632 cm^-1, which varied in intensities among treated and untreated specimens, could be considered to assess the extent of treatment modification. Besides, FTIR results showed that the chemical constituents of bamboo inner and outermost surfaces vary extensively with distinctive changes during treatment modification. The steam component in smoke treatment is assumed to cause a slight increase in the moisture content in the outermost surface of smoked bamboo as evidenced by FTIR results. In addition, the hydrophobic surface of smoked bamboo, which was affected during smoke treatment modification due to superior mean roughness parameter in its outermost surface, impacted its water-repelling ability. From FTIR results, an increase in lignin in bamboo was confirmed at peak 1114 cm^-1, which occurred as a result of thermal effect above a temperature of 100 °C leading to poly-condensation reactions. The increase in lignin is assumed to cause an overall increase in hardness of smoked bamboo which was found to be two-fold higher when compared with the untreated ones. The approach of this research investigation, which has shown the benefit of using spectroscopic techniques to monitor and understand the changes in the hygroscopic nature of bamboo surfaces, can likewise be considered to predict the corresponding effects of treatment modification or degradation on the mechanical properties of natural materials.

Keywords: Raman spectroscopy; bamboo; durability; hygroscopicity; smoke treatment.