CHEMICAL PROPERTIES AND DECAY RESISTANCE OF Eucalyptus grandis WOOD FROM STEAMED LOGS

Recently, the lumber industry in Brazil has passed large change. The native wood of tropical forests have presented use restrictions due to legislation and environmental friendliness. Moreover, Brazil is among the ten countries with largest reforested area, and the Eucalyptus is the most important kind, with about 4.5 million ha (ABRAF, 2010) [1]. However, the Eucalyptus wood shows adverse conditions when it is used in timber and furniture industry. The presence of high levels of growth stress cause cracks and distortions in logs and boards, resulting in low yield of the material. Techniques that have been used to relieve the tensions from growth stress include heating logs at high humidity by certain time. This process is called steaming and leads to a relaxation of tensions in the material through plasticization of lignin. Thus, the steamed wood presents a lower percentage of defects, and better quality during and after the sawing process. However, the thermal treatments modify the features of wood. The objective of this study was to evaluate the effect of log steaming on the chemical properties and biological resistance of Eucalyptus grandis wood to decay fungus Pycnoporus sanguineous. This study utilized wood from 5 years and 11 months old E. grandis trees with diameter of 20 to 22 cm and 6.0 m long. The twelve logs were cutted in half. One of these logs was kept in its original condition (untreated log), and the other piece were reserved for the thermal treatment (steamed log). Two grooves were machined to a depth equal to one third of the radius of each log at 10 cm from the crosscu