Thermal modification of Eucalyptus grandis and Pinus taeda wood
The wood modification industry is currently undergoing major changes, mainly motivated by the environmental and health implications of traditional methods. In the last decades, new technologies for wood modification have reached the market, such is the case of thermal modification, which improves th...
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| Format: | masterThesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://hdl.handle.net/20.500.12008/25953 |
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| Summary: | The wood modification industry is currently undergoing major changes, mainly motivated by the environmental and health implications of traditional methods. In the last decades, new technologies for wood modification have reached the market, such is the case of thermal modification, which improves the properties of wood without the addition of chemicals. This work studies the changes in the properties of Eucalyptus grandis Hill ex Maiden and Pinus taeda L. wood subjected to thermal modification at temperatures between 160°C and 220°C in vacuum, air and nitrogen. Mass loss and volume reduction due to thermal modification were studied, as well as cell wall degradation, measured through lignin content and sugars, namely glucose, xylose, galactose and mannose. The changes in hygroscopicity were also analyzed, in addition to the mechanical properties, measured through the modulus of elasticity and bending strength. Finally, the reversibility of changes in hygroscopicity and dimensional stability of Eucalyptus grandis modified at 200°C was studied. All tested conditions in both species presented mass loss and volume reduction. Degradation of the cell wall constituents was exhibited, mainly due to the reduction of the xylose, galactose and mannose content of thermally modified wood. Equilibrium moisture content was reduced and bending strength was negatively affected by the thermal modification, while the modulus of elasticity presented different behaviors in the two species, showing a decreasing trend in P. taeda wood. Lastly, a certain degree of reversibility in the reduction of hygroscopicity and the improvement in the dimensional stability of thermally modified E. grandis wood was observed. This work provides a comprehensive study of the variations in the properties of two Uruguayan timber species modified with a technology that has the potential to help with the development of the local forestry industry. |
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