The objectives of this work was to evaluate the properties of OSB (Oriented Strand Board). Wood was collected from Eucalyptus grandis, Eucalyptus urophylla and Eucalyptus cloeziana on the municipalities of Ponte Alta and Três Marias, in the state of Minas Gerais. Wood densities were respectively: Ponte Alta (0.55, 0.61 and 0.70g/cm³) and Três Marias (0.56, 0.58 e 0.69g/cm³). Strands of Pinus elliottii, derived from the city of Viçosa, with density of 0.45g/cm³, were added to strands of eucalyptus when necessary to keep board densities close to 0.70g/cm³. Flakes were fabricated in a laboratory disk flaker measuring approximately 20.00 x 0.46 x 90.00 mm. Phenol-formaldehyde adhesive was applied at 8% solid rate, in relation to particle dry mass. Part of the treatment was carried out with flakes from acetylated eucalyptus. The boards were pressed at 170°C and 32 kgf/cm² pressure. Boards properties were determined according to the ABNT NBR 14810-3 (2002) and ASTM-D 1037 (1991) norms. The results were compared using the ANSI/A - 208.1 (1993) and CSA 0437-93 (1993) norms. OSB manufactured with any amount of acetylated flakes was more stable and absorbed less water. However the resistance to perpendicular traction of OSB with 100% of acetylated flakes was inferior to the stipulated by the CSA O437-0/93 (1993) norm. It was also found that acetylation had a negative effect on screw withdrawal resistance, module of rupture (parallel and perpendicular) and longitudinal compression resistance (perpendicular) of Eucalyptus grandis OSB having 100% of their flakes acetylated. Boards that presented numerically the highest means were manufactured with non-acetylated flakes of Eucalyptus grandis (Janka hardness) and Eucalyptus cloeziana mixed with Pinus sp (module of rupture). Only resistance to longitudinal compression was affected by the wood origin. OSB manufactured with Eucalyptus urophylla wood, from the Cerrado, had lower means than OSB made of the same species, however, from Vale do Rio Doce.
OSB; Eucalyptus grandis; Eucalyptus urophylla; Eucalyptus cloeziana; Pinus elliottii; acetylation
