Magnetic Resonance Studies of Thermally Modified Wood

H. Sivonen, Sirkka L. Maunu, F. Sundholm, Saila Jämsä, Pertti Viitaniemi

Research output: Contribution to journalArticleScientificpeer-review

225 Citations (Scopus)

Abstract

Thermal modification of wood produces a wood material with many interesting properties, such as enhanced dimensional stability, lower equilibrium moisture content and increased biological durability. Changes in the chemical structure of pine (Pinus sylvestris) caused by thermal treatment were investigated by studying various components of wood using 13C CPMAS NMR spectroscopy. Electron spin resonance (ESR) spectroscopy on the same set of samples was used to study the formation and stability of free radicals formed during the treatment.
The most remarkable changes revealed by solid state NMR were the increase in relative crystallinity of cellulose and destruction and deacetylation of hemicelluloses. Changes in the lignin fraction were mostly registered as diminishment in the methoxyl content, although the intensity of the aromatic region increased relative to the carbohydrate fraction during the treatment.
Increase in the intensities of the ESR signals from thermally treated wood samples proves the formation of stable free radicals. In addition, radical formation is believed to take part in condensation reactions leading to crosslinks within the lignin and possibly between lignin and other wood components.
Both of the methods used indicate that the changes are most remarkable when the treatment temperature is over 200°C.
Original languageEnglish
Pages (from-to)648-654
JournalHolzforschung
Volume56
Issue number6
DOIs
Publication statusPublished - 2002
MoE publication typeA1 Journal article-refereed

Fingerprint

Magnetic resonance
Wood
Lignin
Free radicals
Free Radicals
Electron spin resonance spectroscopy
Condensation reactions
Dimensional stability
Carbohydrates
Cellulose
Nuclear magnetic resonance spectroscopy
Paramagnetic resonance
Durability
Moisture
Heat treatment
Nuclear magnetic resonance
Temperature

Keywords

  • Pinus sylvestris
  • thermally modified wood
  • C CPMAS NMR spectroscopy
  • crystallinity index
  • dipolar dephasing
  • ESR spectroscopy
  • free radicals

Cite this

Sivonen, H., Maunu, S. L., Sundholm, F., Jämsä, S., & Viitaniemi, P. (2002). Magnetic Resonance Studies of Thermally Modified Wood. Holzforschung, 56(6), 648-654. https://doi.org/10.1515/HF.2002.098
Sivonen, H. ; Maunu, Sirkka L. ; Sundholm, F. ; Jämsä, Saila ; Viitaniemi, Pertti. / Magnetic Resonance Studies of Thermally Modified Wood. In: Holzforschung. 2002 ; Vol. 56, No. 6. pp. 648-654.
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Sivonen, H, Maunu, SL, Sundholm, F, Jämsä, S & Viitaniemi, P 2002, 'Magnetic Resonance Studies of Thermally Modified Wood', Holzforschung, vol. 56, no. 6, pp. 648-654. https://doi.org/10.1515/HF.2002.098

Magnetic Resonance Studies of Thermally Modified Wood. / Sivonen, H.; Maunu, Sirkka L.; Sundholm, F.; Jämsä, Saila; Viitaniemi, Pertti.

In: Holzforschung, Vol. 56, No. 6, 2002, p. 648-654.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Magnetic Resonance Studies of Thermally Modified Wood

AU - Sivonen, H.

AU - Maunu, Sirkka L.

AU - Sundholm, F.

AU - Jämsä, Saila

AU - Viitaniemi, Pertti

PY - 2002

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N2 - Thermal modification of wood produces a wood material with many interesting properties, such as enhanced dimensional stability, lower equilibrium moisture content and increased biological durability. Changes in the chemical structure of pine (Pinus sylvestris) caused by thermal treatment were investigated by studying various components of wood using 13C CPMAS NMR spectroscopy. Electron spin resonance (ESR) spectroscopy on the same set of samples was used to study the formation and stability of free radicals formed during the treatment. The most remarkable changes revealed by solid state NMR were the increase in relative crystallinity of cellulose and destruction and deacetylation of hemicelluloses. Changes in the lignin fraction were mostly registered as diminishment in the methoxyl content, although the intensity of the aromatic region increased relative to the carbohydrate fraction during the treatment. Increase in the intensities of the ESR signals from thermally treated wood samples proves the formation of stable free radicals. In addition, radical formation is believed to take part in condensation reactions leading to crosslinks within the lignin and possibly between lignin and other wood components. Both of the methods used indicate that the changes are most remarkable when the treatment temperature is over 200°C.

AB - Thermal modification of wood produces a wood material with many interesting properties, such as enhanced dimensional stability, lower equilibrium moisture content and increased biological durability. Changes in the chemical structure of pine (Pinus sylvestris) caused by thermal treatment were investigated by studying various components of wood using 13C CPMAS NMR spectroscopy. Electron spin resonance (ESR) spectroscopy on the same set of samples was used to study the formation and stability of free radicals formed during the treatment. The most remarkable changes revealed by solid state NMR were the increase in relative crystallinity of cellulose and destruction and deacetylation of hemicelluloses. Changes in the lignin fraction were mostly registered as diminishment in the methoxyl content, although the intensity of the aromatic region increased relative to the carbohydrate fraction during the treatment. Increase in the intensities of the ESR signals from thermally treated wood samples proves the formation of stable free radicals. In addition, radical formation is believed to take part in condensation reactions leading to crosslinks within the lignin and possibly between lignin and other wood components. Both of the methods used indicate that the changes are most remarkable when the treatment temperature is over 200°C.

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Sivonen H, Maunu SL, Sundholm F, Jämsä S, Viitaniemi P. Magnetic Resonance Studies of Thermally Modified Wood. Holzforschung. 2002;56(6):648-654. https://doi.org/10.1515/HF.2002.098