Thermal modification is a treatment that seeks to improve the properties of wood and reduce the heterogeneity in its color. The objective of this work was to evaluate the effect of thermal treatment on the anatomical, chemical, physical, mechanical, colorimetric, and thermal stability properties of teakwood. For this, teakwood samples were treated by an industrial autoclave at final cycle temperature of 160 ºC. The reduction of cell wall thickness, the formation of cross-fissures and the crystallization of the wax inside the pores were observed in the anatomical structure. Chemically, the extractives evaporated and the polysaccharides ruptured, of which hemicellulose was the most affected. The heat treatment promoted lower equilibrium moisture, reducing the hygroscopicity and improving the dimensional stability of the wood. Considering the mechanical properties, the rupture modulus and the longitudinal and tangential hardness decreased after the heat treatment. The color of the wood changed significantly, from pink to dark brown. The treated wood had higher thermal stability, with greater weight loss at higher temperatures than the untreated wood.

The modification of wood by thermal treatments produces characteristic changes in its chemical composition and surface color and can improve the structural and esthetic quality. The objective of this paper is to evaluate the potential of near infrared and visible spectroscopy to predict the modifications in chemical composition of Eucalyptys grandis and Pinus taeda after thermal treatment. Near infrared and visible spectra were collected directly on the longitudinal surface of wood samples. The thermally modified wood of both species showed higher content of lignin and extractives than the untreated wood. There was darkening of thermally modified wood, as a result of chemical modification caused by heat. The Near infrared/visible technique identified the groups that were modified by treatment. NIR and visible spectroscopy can be used to predict chemical composition of natural or thermally treated Eucalyptus grandis and Pinus taeda.

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RESUMO O objetivo deste trabalho foi avaliar a qualidade das juntas coladas de madeira de Inga alba e Swartzia recurva utilizando adesivos a base de acetato de polivinila (PVAc) e emulsão polimérica de isocianato (EPI) em gramaturas de 150 e 200 g.m². A resistência das juntas coladas foi avaliada por meio de ensaios de cisalhamento, com base nos procedimentos descritos na norma EN 13354 (2008). O aumento na gramatura não influenciou nos resultados de cisalhamento, indicando os benefícios em termos econômicos com a redução no consumo do adesivo. As juntas coladas com madeira de Swartzia recurva com o adesivo EPI, nas duas gramaturas avaliadas, atingiram o valor mínimo de 2,5 MPa referente ao 5º percentil inferior estabelecido pela norma EN 13353 (2008). Os resultados demonstraram a viabilidade de uso da madeira de Inga alba e Swartzia recurva para produção de painéis colados lateralmente - EGP, com adesivo EPI e gramatura de 150 g.m².

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The aim of this study was to characterize microfibrillated cellulose (MFC) produced with a Masuko Sangyo Super Masscolloider using bleached and unbleached pulp of Eucalyptus spp. The MFC was characterized regarding morphology (TEM), crystallinity, viscosity, zeta potential and thermal properties (TGA). Regardless of the fiber type, the processing dramatically reduced the dimensions of the material, so as to obtain structures with nanometric dimensions. MFC produced with unbleached pulp preserved the original brown color of the pulp, which may be advantageous for some applications in the packaging sector, while films produced with bleached pulp were more translucent. The MFC showed lower values of viscosity and crystallinity index in relation to cellulosic pulp. The zeta potential was influenced by the type of fiber used. The main thermal transitions in MFC occurred after 200 ºC, demonstrating the potential of this material forhigh-temperature applications.

A primeira característica da madeira perceptível à visão humana é a cor, com possibilidade de indicar seu uso, além de correlacionar-se com as exigências do consumidor final. Por ser um parâmetro de difícil determinação, devido à sua subjetividade, foram desenvolvidos métodos para determinação matemática da cor, como o método comparativo de Munsell e o método quantitativo, denominado colorimetria. Ao longo do tempo, o segundo método se consolidou devido à sua alta precisão. O método colorimétrico mais usado na ciência da madeira é o sistema CIELAB, constituído por três eixos, a coordenada L*, que representa a luminosidade ou claridade, a coordenada a*, que representa o eixo vermelho-verde, e a coordenada b*, que representa o eixo amarelo-azul. Além da classificação colorimétrica da madeira, a colorimetria é eficiente para determinação de algumas propriedades da madeira, do efeito da termorretificação e da ação de agentes biodeterioradores e do intemperismo na madeira. O principal objetivo desse trabalho foi evidenciar a importância e a aplicabilidade da colorimetria como técnica aplicada à ciência e tecnologia da madeira.