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RESUMO Estudos sobre novos adesivos ou resinas para colagem de madeira e derivados estão sendo realizados com a intenção de melhorar suas propriedades, levando em consideração um menor impacto ambiental. Por este motivo, novas formulações de adesivos de acetato de polivinila (PVA) vêm sendo desenvolvidas, pois estes não possuem em sua composição compostos químicos extremamente poluentes e prejudiciais à saúde, como é o caso de resinas à base de formaldeído, que, por sua vez, são as mais comumente utilizadas hoje em dia para a produção de painéis de madeira. Este trabalho testou três formulações diferentes de adesivos PVA, com duas combinações de tempo e temperatura de prensagem, para a produção de painéis compensados de Eucalyptus sp., obtendo bons resultados com relação à resistência ao cisalhamento na linha de cola, a qual foi superior para os adesivos PVA se comparados com painéis produzidos com ureia e fenol-formaldeído, encontrados na literatura.

The use of residues from human activities has been currently gaining ground in the national and international markets, aiming toward the production of more sustainable materials that are less aggressive to the environment. Reusing and adding value to new products has also become an important factor in reducing production costs and the best alternative for this is process optimization. The choice for residual balsa wood was due to its rapid growth and low density, as well as for its ease of engineering and determining the ideal amount of resin for different types of panels. This study aims to investigate the influence of the content variation of castor oil-based polyurethane resin on the physical and mechanical properties of OSB board particles made from residual balsa wood in reforestation areas. The panels were produced with 8, 10, and 12 % commercial castor oil-based polyurethane resin and 9 mm long particles; their physical and mechanical characterizations followed international normative recommendations. The results indicated that the panels with resin contents higher than 10 % reached the minimum regulatory requirements for type 2 OSB panels, suitable for structural application. On the other hand, the panels produced with 8 % resin reached the minimum requirements for type 1 OSB panels, suitable for non-structural use by the furniture industry, such as linings and partitions. Therefore, our study concludes that the variation of resin contents for OSB panels of residual balsa wood allowed us to achieve optimal levels for the use of castor oil-based polyurethane resin, reaching minimum values recommended by regulations for OSB panels type 1 and 2 and a great possibility of application of this product for engineered materials.

ABSTRACT To simplify the characterization of wood species, the Brazilian standard document ABNT NBR 7190-1 (2022) establishes the determination of mechanical properties employing the characteristic strength in the compression parallel to grain (fc0,k). This mechanical property is estimated using the linear relation given by the following expression fv0,k = 0.12·fc0,k Brazilian and European standard documents support the estimation of fv0,k using relations among properties. However, the European guidelines in the EN 384 (2019) have used the conventional characteristic strength in the static bending test (fM,k). Thus, this study aimed to investigate the efficiency of the ratio fv0,k = 0.12·fc0,k for adopting 30 hardwoods. The variance analysis results demonstrate the divergence among the experimental outcomes and those values estimated using the relation cited. Therefore, regression models at two parameters were considered to obtain more accurate estimates of fv0,k by adopting fc0,k, and fM,k as independent variables. Regarding the results, the geometric (R² = 80.80%) and linear (R² = 74.19%) models were the most accurate for the estimates of fv0,k in terms of fc0,k, and fM,k, respectively. This fact evinces the good accuracy of the models under consideration, which may provide a more rigorous structural design compared to the correlation currently prescribed by the ABNT NBR 7190-1 (2022).

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.

Plywood is a wood panel that can be used both in the furniture industry and in construction due to its structural use. However, to be used in construction, it needs to be resistant against wood decay agents and water, without compromising its mechanical properties. The heat treatment is an alternative treatment which improves the wood resistance to fungi and improves its dimensional stability. Thus, the objective of this study is to evaluate the influence of the heat treatment with three different temperatures, 160, 180 and 200°C in the wettability of wood veneers and the shear strength in the bond line of the plywood produced with them. To do so, it was carried out the wettability testing using digital goniometer in the treated veneers at three temperatures and for the control specimen. Besides, it was carried out the shear strength in the bond line test, for testing the quality of bonding according to ABNT NBR ISO 12466-1 (2006). Because of the results obtained, it could be seen that the surface of the treated wood became more hydrophobic with increasing temperature, and this also resulted in a decrease in shear strength in the bond line, once the adhesive used (phenol-formaldehyde) is water based, however, the regulatory requirements have been met.

Productos derivados de madera son una propuesta interesante en la ampliación de los materiales que son empleados en la industria de la construcción civil, de muebles y otros usos. Entre los productos derivados de madera se destacan los tableros de fibra de media densidad (Medium Density Fiberboard - MDF), un producto que ofrece buena condición de trabajo. MDF es fabricado en seco, hecho con fibras lignocelulósicas, combinadas con resina, compactados por prensado en caliente. Este trabajo presenta la producción de MDF utilizando fibras de eucalipto y diferentes porcentajes de adhesivo poliuretano de origen natural. Después de la fabricación fueron realizados ensayos de caracterizaciones físico-mecánicos y comparados con especificaciones contenidas en la norma Europea de tableros MDF (Euro MDF Board). Wood-based products are an interesting alternative to expand the range of materials for use in civil construction, cabinetmaking and others applications. Among wood-based products are detached the Medium Density Fiberboard (MDF), a product that it offers good work condition. MDF is manufactured to dry, made of fibers lignocellulosics, combined with resin, and compacted by hot pressure. This paper shows the production of MDF using Eucalyptus fibers and different content polyurethane resin. After production were making physical and mechanical characterization tests and compared with the specifications contained in the European Code for MDF Board (Euro MDF Board).

Productos derivados de madera son una propuesta interesante en la ampliación de los materiales que son empleados en la industria de la construcción civil, de muebles y otros usos. Entre los productos derivados de madera se destacan los tableros de fibra de media densidad (Medium Density Fiberboard - MDF), un producto que ofrece buena condición de trabajo. MDF es fabricado en seco, hecho con fibras lignocelulósicas, combinadas con resina, compactados por prensado en caliente. Este trabajo presenta la producción de MDF utilizando fibras de eucalipto y diferentes porcentajes de adhesivo poliuretano de origen natural. Después de la fabricación fueron realizados ensayos de caracterizaciones físico-mecánicos y comparados con especificaciones contenidas en la norma Europea de tableros MDF (Euro MDF Board)Wood-based products are an interesting alternative to expand the range of materials for use in civil construction, cabinetmaking and others applications. Among wood-based products are detached the Medium Density Fiberboard (MDF), a product that it offers good work condition. MDF is manufactured to dry, made of fibers lignocellulosics, combined with resin, and compacted by hot pressure. This paper shows the production of MDF using Eucalyptus fibers and different content polyurethane resin. After production were making physical and mechanical characterization tests and compared with the specifications contained in the European Code for MDF Board (Euro MDF Board)