Nondestructive evaluation of heat-treated Eucalyptus grandis Hill ex Maiden wood using stress wave method

The objectives of this study were to evaluate the effect of heat treatment of eucalypt wood (Eucalyptus grandis Hill ex Maiden) on the dynamic modulus of elasticity by using the stress wave nondestructive method and also to determine the air-dry density variation, weight loss and equilibrium moisture content following treatment. Heat treatments were performed at four different temperatures (180, 200, 215 and 230°C) and for three different durations (15 min, 2 and 4 h). The results revealed a significant reduction in air-dry density following heat treatment independent of temperature and time. A significant weight loss was observed between and within treatments. The treatment at 230°C for 2 and 4 h produced a weight loss of 20.5 and 26.5%, respectively, which was statistically different from other treatment conditions. The dynamic modulus of elasticity decreased by about 13% in the most severe treatment (230°C for 4 h). Depending on the temperature and time, the equilibrium moisture content was significantly reduced within the range of 40–74%.