The use of wood-base panels in humid environments, in general, presents low durability due to contact with water. In order to increase durability and reduce the attack of fungi, studies had been developed using resin with zinc oxide (ZnO) nanoparticles. This work aimed to produce medium density fiberboard with urea-formaldehyde resin and melamine-formaldehyde adding 0.5% and 1.0% of ZnO nanoparticles for the physical properties evaluation. All treatments were classified as medium density according to ABNT NBR 15.316-2 (2015) with values ranging between 550 and 800 kg*m-³. No differences were found between the two commercial adhesives used. The addition of 1.0% of nanoparticles resulted in lower density panels, higher moisture contents, and, after immersion in water for 24 hours, higher values of swelling in thickness. These results are explained by the lower compaction of the boards due to rapid cure of the adhesive using higher percentages of ZnO nanoparticles. The best treatment of the panels was with melamine-formaldehyde resin and 0.5% of nanoparticles.

Wood industries use thermal and thermomechanical treatments as ecological approaches to increase the durability of wood products, avoiding the need for chemical additives. In this regard, the aim of this study was to compare the physical and mechanical properties of plywood made from veneers treated at different temperatures using thermal and thermomechanical processes, with untreated panels serving as a control. The treatment process involved Pinus taeda veneers submitted to treatment in a hot press at 1.0 MPa in a laboratory oven at temperatures of 160 °C, 180 °C, and 200 °C for 30 min. For bonding the veneers, a vegetable-based polyurethane resin derived from castor oil with a grammage of 395 g/m² was used, applying pressing conditions at 90 °C, 0.6 MPa, and 10 min. Our results indicate that temperature significantly influences plywood properties, playing a key role in the choice of equipment for the treatment process. Regardless of the method employed, the treatment resulted in an improvement in the hydrophobicity of the veneers due to the decrease in hemicellulose content. Notably, the reduction in strength and stiffness caused by the loss of cell wall polymers was not statistically significant. The treatment was successful in softening the wood material, reducing roughness, and increasing wettability. Despite a minimum of 20% reduction in glue line tension, the samples still surpassed the 1 MPa mark, showing satisfactory results. This demonstrates the feasibility of adjusting treatment variables to ensure the proper use of this adhesive.

Oriented Strand Board is a structural wood composite with applications that require good physical and mechanical performance. The addition of ZnO nanoparticles is an alternative that has been studied in order to improve the properties of Oriented Strand Board panels. However, there is no information about its effect Oriented Strand Board. The aim of this work was to evaluate the influence of the addition of zinc oxide nanoparticles in two different percentages (0,25 % and 0,50 %) on the physical-mechanical properties of Oriented Strand Board panels produced with phenol-formaldehyde resin and on the heat transfer during hot-pressing. Oriented Strand Board panels were produced and tested according to European Standards. The addition of ZnO nanoparticles improved the dimensional stability of the panel, reducing its thickness swelling, and also increased the screw withdraw strength. The heat transfer during hot-pressing increased the temperature more quickly on boards with nanoparticles addition; on the other hand the final temperature of the control treatment was higher.