Abstract
This study was aimed at evaluating the effect of thermal treatment on the physical and mechanical properties of Eucalyptus grandis wood. Boards were taken from 5.9-year-old E. grandis trees. The boards were thermally modified at temperatures up to 220°C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, in Brazil. The results indicated that the thermal modification caused significant decreases of up to: (1) 49.3% and 10.5% in the equilibrium moisture content and in the density of wood, respectively; (2) 53.3% in the volumetric swelling; (3) 52.3% in the modulus of rupture at static bending, without changes in the compressive strength parallel to grain and the respective modulus of elasticity; and (4) 20.7% in the Janka hardness. It was found that the specific gravity and compression parallel to the grain test were not the most suitable ones for evaluating the quality of thermally modified wood.
Zusammenfassung
Ziel dieser Studie war es, den Einfluss einer thermischen Behandlung auf die physikalischen und mechanischen Eigenschaften von Eucalyptus grandis Holz zu untersuchen. Aus 5,9-Jahre alten E. grandis Bäumen wurden Bretter eingeschnitten und im Trocknungslabor der UNESP in Botucatu, SP, in Brasilien bei Temperaturen bis zu 220°C thermisch modifiziert. Die thermische Modifikation führte zu folgenden Ergebnissen: Rückgang der (1) Gleichgewichtsfeuchte um bis zu 49,3 % und der Dichte um bis zu 10,5 %, (2) der Volumenquellung um bis zu 53,3 %, (3) der statischen Biegefestigkeit um bis zu 52,3 % und (4) der Janka-Härte um bis zu 20,7 %. Die Druckfestigkeit in Faserrichtung sowie der entsprechende Elastizitätsmodul änderten sich nicht. Es zeigte sich, dass die Rohdichte und die Druckfestigkeit in Faserrichtung zur Bestimmung der Qualität von thermisch modifiziertem Holz nicht gut geeignet sind.
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Acknowledgements
The authors thank the Research Assistance Foundation from São Paulo (FAPESP) and the Coordinator for the Improvement of Higher Level Personnel (CAPES), Brazil, for financial support through grant numbers 05/59074-7 and PNPD-02405/09-1.
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Calonego, F.W., Severo, E.T.D. & Ballarin, A.W. Physical and mechanical properties of thermally modified wood from E. grandis . Eur. J. Wood Prod. 70, 453–460 (2012). https://doi.org/10.1007/s00107-011-0568-5
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DOI: https://doi.org/10.1007/s00107-011-0568-5