Publicación: DENSIFICATION OF WOOD VANEERS COMBINED WITW OIL-HEAT TREATMENT. PART III: CELL WALL MECHANICAL PROPERTIES DETYRMINED BY NAOINDENTATION.
Fecha
2012
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COMPRESSION UNDER THE EFFECT OF HEAT AND STEAM, ALSO CALLED THERMO-HYGROMECHANICAL (THM) DENSIFICATION, CAN INCREASE WOOD DENSITY AND THEREFORE IMPROVE ITS STRENGTH, STIFFNESS, AND HARDNESS. OIL-HEAT TREATMENT (OHT) IS ALSO KNOWN TO REDUCE WOOD?S HYGROSCOPICITY AND IMPROVE DIMENSIONAL STABILITY. A COMBINATION OF BOTH TREATMENTS CAN THEREFORE PRODUCE WOOD WITH IMPROVED MECHANICAL PROPERTIES AND DIMENSIONAL STABILITY. THE OBJECTIVE OF THIS PROJECT WAS TO DETERMINE CELL WALL MECHANICAL PROPERTIES OF THM-DENSIFIED AND OHT WOOD. TREMBLING ASPEN VENEERS WERE DENSIFIED BY A THM PROCESS AND SUBSEQUENTLY TREATED IN CANOLA OIL AT 200 AND 220°C. NANOINDENTATIONS WERE PERFORMED IN EARLYWOOD CELL WALLS. THE RESULTS SHOW THAT CELL WALL LONGITUDINAL MODULUS OF ELASTICITY INCREASED SIGNIFICANTLY FROM 13.5 GPA FOR THE CONTROL TO A MAXIMUM OF 18.2 GPA FOR THM DENSIFIED WOOD WITH OR WITHOUT OHT. CELL WALL HARDNESS INCREASED FROM 0.27 GPA TO A MAXIMUM OF 0.43 GPA. BOTH THM DENSIFICATION AND OHT SIGNIFICANTLY INCREASED CELL WALL HARDNESS. THEREFORE, THE INCREASE IN MECHANICAL PROPERTIES OF THM-DENSIFIED AND OHT WOOD CAN BE DUE TO AN INCREASE IN WOOD DENSITY RESULTING FROM A REDUCTION IN POROSITY BUT ALSO TO AN INCREASE IN THE MECHANICAL PROPERTIES OF THE CELL WALL.
