Abstract: The proper choice of raw materials and manufacturing parameters for Cross Laminated Timber is essential to promote the proper bonding of the lamellas, aiming at their application in construction. However, few Brazilian species are currently used in the production of Cross Laminated Timber. The aim of this work was to characterize the bonding quality of four Brazilian reforestation species (Pinus elliottii (pino ellioti), Eucalyptus grandis (eucalipto), Toona ciliata (toona) and Acrocarpus fraxinifolius (lazcar)) in the manufacture of Cross Laminated Timber with two-component polyurethane adhesive and five different pressure levels (from 0,1 MPa to 1,3 MPa). Bonding quality was evaluated through delamination and glue line shear tests based on the European standard. Delamination was affected by the wood species, and the best adhesion occurred for the Cross Laminated Timber manufactured with Pinus elliottii (pino ellioti) and Acrocarpus fraxinifolius (lazcar) at the bonding pressure of 0,7 MPa. Cross Laminated Timber bonding pressure did not affect the percentage of wood in the shear test fractured surface, whereas higher density Cross Laminated Timber showed higher percentages.

Abstract The Brazilian Code ABNT NBR 7190 (1997) is currently under review process and one of the proposals is the change and add of some test procedures. Several specimen geometric configurations and test conditions have been evaluated by the study committee CE-02:126.10. The aim of this paper was the analysis of the tensile strength perpendicular to the grain through the current Brazilian Code and from an adaptation of ISO 13910 (2005). Pine and Indian Cedar were used and simplified relationships were proposed. Numerical simulations were performed to identify the stress distributions in the specimens. The results obtained by ISO 13910 (2005) did not differ statistically for the two species. Brazilian standard method cedar had a higher strength value than pine. The simplified ratios obtained ranged between 0,017 and 0,123. The numerical simulations of ISO 13910 (2005) specimens showed predominant failure by tension in the lower fiber due to stress concentration.

ABSTRACT The present research intended to propose and evaluate regression models which estimate toughness property as a function of physical, chemical properties of thermally modified hardwood and thermal treatment temperature, using linear, quadratic, cubic, exponential, logarithmic, geometric and multiple linear models. Commercial thermally modified woods were used on the study, being characterized for all referred properties, totalizing 450 experimental determinations. The analyzed models presented a low and moderate coefficient of determination, indicating the impossibility to use such models in the estimation of toughness as a function of physical and chemical factors

RESUMO Este estudo teve como objetivo avaliar a influência do tratamento térmico comercial no Eucalyptus grandis considerando suas propriedades físicas, químicas e mecânicas. As amostras de madeira foram tratadas termicamente em autoclave com vapor saturado e aplicação de pressão em quatro diferentes temperaturas: 155, 165, 175 e 185 º C. As propriedades físicas, químicas e mecânicas foram alteradas devido ao tratamento térmico. O teor de extrativos variou entre 6,06% e 28,75%; lignina entre 28,93% e 37,96%; holocelulose entre 65,01% e 38,12%. As propriedades mecânicas reduziram significativamente com o aumento da temperatura do tratamento térmico. Com o conjunto de dados obtidos, foi possível gerar modelos de regressão significativos e de alta precisão capazes de estimar tais propriedades para temperaturas de tratamento térmico não estudadas experimentalmente, possibilitando a determinação da temperatura de tratamento térmico mais adequada para atingir determinado valor de propriedade do tratado madeira.

ABSTRACT This study aimed to evaluate the influence of commercial thermal treatment on Eucalyptus grandis considering its physical, chemical, and mechanical properties. The wood samples were heat-treated in an autoclave with saturated steam and pressure application at four different temperatures: 155, 165, 175, and 185 ºC. The physical, chemical, and mechanical properties were altered due to the heat treatment. The extractives content varied between 6.06% and 28.75%; lignin between 28.93% and 37.96%; holocellulose between 65.01% and 38.12%. The mechanical properties reduced significantly with the increase of the heat treatment temperature. Through the set of data obtained, it was possible to generate significant and high precision regression models capable of estimating such properties for heat treatment temperatures not studied experimentally, enabling the determination of the most suitable temperature of heat treatment to achieve a certain property value of the treated wood.