Resistance of Untreated and Torrefied Medium-Density Fiberboard (MDF) Residues to Xylophage Fungi

Abstract

The manufacture of wood panels generates a large amount of waste. This material can be an option for renewable energy generation. However, long-term storage, exposure to moisture and contact of these panels with the soil facilitate colonization by xylophagous organisms. Torrefaction, a heat treatment between 200 and 300 °C in an oxygen-free atmosphere, is a process that decreases hygroscopicity while increasing carbon content, energy efficiency and resistance to fungal attack. This work aimed to evaluate the resistance of MDF panel residues. The MDF panels were produced using eucalyptus wood and bonded with thermosetting synthetic resin, under high temperature and pressure, torrefied at 300 °C for 20, 30 and 40 min and exposed to the xylophagous fungi of the white rot, Irpex lacteus (Fr.) Fr. (1828) and Trametes versicolor, and that of the brown rot, Postia placenta. After the 12-week evaluation period under fungal exposure, the mass loss of the samples attacked by T. versicolor and P. placenta was similar between treatments, except the MDF untreated, which had greater mass losses from the fungus Irpex lacteus. The torrefaction process increased the material resistance to deterioration by fungi, with an inverse correlation between the torrefaction period and the mass losses by fungal attack of the MDF panel residues.