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The need for more technological products increases with nanomaterials as a viable proposal, presenting good results in many different industrial sectors, especially in wood panels. Particleboards are composites of wood that have been extensively studied, mainly in relation to the adhesives used in their manufacture, which have an influence on particleboard properties. Thus, as a way of improving these adhesives, zinc oxide nanoparticles were added, giving new properties to the particleboard. Thereby, the present work aimed to produce particleboard with the wood of Eucalyptus Urophila x Grandis hybrid and urea-formaldehyde adhesive with ZnO nanoparticles addition. The physical tests performed were density, moisture content, and thickness swelling. The mechanical tests performed were the modulus of elasticity, modulus of rupture, and bonding tests. The results obtained were submitted to statistical analysis and compared with the requirements standards, as well as with works found in the literature. The addition of zinc oxide nanoparticles did not exercise influence on mechanical tests; however, the physical properties were improved, mainly decreasing the thickness swelling, which is usually a problem for wood products.

Tropical species are widely used in construction, and their physical and mechanical properties have been important characteristics with direct impact on the design of structures, especially the strength and stiffness of wood applied in them. Tests to obtain both parameters are conducted under ABNT NBR 7190 (1997) guidelines in Brazil, being rarely found in some research centers because of the higher costs of testing equipment. For instance, the toughness test depends on equipment with a pendulum, whose device requires accuracy and maintenance for reliable analyses. This paper aims to estimate toughness through another property more easily found, given by the compression strength parallel to the grain. For this, 20 tropical wood species of the South American region were used to obtain initial values of these properties. The characteristic values of the compression strength parallel to the grain as well as linear and quadratic regression models were obtained. Statistical analysis was performed and confirmed that a linear model gave better predictions than a quadratic model.

Tendo em vista o grande potencial do mercado de produtos derivados de madeira no Brasil, destacando-se o setor de painéis, estudos voltados para aplicação de novas tecnologias na fabricação dos mesmos são imprescindíveis. É preciso obter painéis mais resistentes a esforços, ao contato com água e agentes biodegradadores, porém sem aumentar os custos de produção. Sendo assim, considerando a tendência atual do estudo de materiais nanopartículados, este trabalho teve como objetivo apresentar um levantamento das principais pesquisas relacionadas a adição de nanopartículas em painéis de madeira. Verificando-se que, apesar das constantes melhoras em suas propriedades físico-mecânicas, ainda é preciso maior aprofundamento no tema.

Made available in DSpace on 2020-12-12T01:46:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The use of particleboards (PB) has increased quickly as an alternative engineered wood product mainly due to its having a better ratio of resistance to weight and more elimination of wood defects, such as the presence of knots. Although the panel industry has been constantly growing, innovations are still necessary to improve the final product. The use of metallic oxide nanoparticles on the wood-based panels has the potential to increase the heat transfer process and improve the physico-mechanical properties. The aim of this work was to evaluate the influence of the addition of zinc oxide (ZnO) nanoparticles in PB, correlating the physical and mechanical properties of the panel with the heat transfer process at 180 °C. The results were compared with the Brazilian standard ABNT NBR 14810-2 (2013) and the European standard EN 312 (2010), as well with works found in literature. The results showed a homogenous heat distribution during the pressing, which improved physical properties, decreasing the 24h swelling from 22.2% to 14.9% and the 24 h absorption from 30.29% to 21.0%. Besides that, MOR values was increased from 11.3 MPa to 14.5 MPa and the MOE from 1880 MPa to 2510 MPa. Department of Mechanical Engineering São Paulo State University (UNESP), Avenida Ariberto Pereira da Cunha Faculty of Engineering and Architecture FUMEC University Department of Civil Engineering Federal University of São Carlos (UFSCar) Department of Structures Engineering Engineering School of São Carlos University of São Paulo (EESC/USP) São Paulo State University (UNESP) Campus of Itapeva, Rua Geraldo Alckmin Department of Mechanical Engineering São Paulo State University (UNESP), Avenida Ariberto Pereira da Cunha São Paulo State University (UNESP) Campus of Itapeva, Rua Geraldo Alckmin

O uso de nanopartículas tem ganhado espaço no mercado, principalmente pela capacidade de atribuir novos comportamentos e novas propriedades a diferentes produtos. Assim, o uso de nanopartículas em painéis particulados revela a possibilidade de aprimoramento do desempenho desses, com novas alternativas para suas aplicações. Com isso, este trabalho avaliou a adição de 0,5% de nanopartículas de Al2O3 e CuO em painéis MDP produzidos com ureia-formaldeído e prensados a 150 ºC, verificando a interferência do material adicionado e analisando suas propriedades físicas. Os ensaios físicos analisados foram, inchamento, absorção, densidade e teor de umidade. Os resultados obtidos foram comparados com as normas NBR 14810-2:2018, EN 312:2003 e ANSI 208-1:2009, bem como com trabalhos da literatura, mostrando que a adição das nanopartículas proporciona um pequeno aumento da densidade dos painéis, sem interferência no teor de umidade, indicando também que o desempenho em contato com a água sofre influência da interação adesivo-madeira.

Made available in DSpace on 2020-12-12T01:39:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 The aim of this paper was to investigate the influence of zinc oxide (ZnO) nanoparticles on the resistance of pine wood to fire and ultraviolet (UV) radiation. The ZnO nanoparticles were prepared from aqueous zinc nitrate via a proteic sol-gel method. Dried samples were impregnated using immersion in an aqueous solution of ZnO nanoparticles in the amount of 1 wt.% wood. Samples were exposed to an open flame to test the fire retardance, and a high-pressure UV lamp was used to test the UV resistance. The results showed an improvement in the fire retardance and UV radiation resistance after the impregnation of ZnO nanoparticles. São Paulo State University (UNESP) Campus Itapeva, Rua Geraldo Alckmin, 519 São Paulo State University (UNESP) Campus Itapeva, Rua Geraldo Alckmin, 519