ABSTRACT Background: Determining the basic density of the wood is usually defined as a simple process, but it requires caution and the operator’s skill to avoid errors in the analysis. In addition, it involves sample preparation and time to saturate the wood until obtaining the dry sample mass. The development of alternative measurement techniques could reduce the time to obtain the results and provide reliable values. Therefore, this study aimed to develop multivariate models to estimate the basic density of native woods using near-infrared spectra (NIR). Basic densities were determined by the water immersion method, and the values were associated with NIR signatures. Spectra were directly collected on the wood transversal and radial faces with an integrating sphere. Partial least squares regression (PLS-R) was calibrated and validated to estimate basic density based on spectral signatures. Results: In the cross-validation and prediction of the models, the results were promising. The coefficients of determination varied from 0.87 to 0.93 with a standard error of 0.01 %. The partial least squares discriminant analysis (PLS-DA) efficiently classified the wood species. The ratio of performance to deviation obtained satisfactory values, a minimum of 2.81 and a maximum of 4.20. Conclusion: The statistical parameters of the models based on NIR spectra showed potential for density measurements in floors, furniture, and solid wood products.

Resumo Objetivou-se avaliar o efeito do tratamento térmico nas propriedades físicas da madeira de Buchenavia sp. Os tratamentos térmicos foram feitos em temperaturas de 180 °C e 200 °C durante 2 h. Avaliou-se a densidade aparente (AD), densidade básica (BD), porosidade (Ф), perda de massa, contração longitudinal (LS), radial (RS), tangencial (TS) e volumétrica (VS) e fator anisotrópico (AF). Os menores valores de densidade básica (0,67 g cm -3 ), densidade aparente (0,77 g cm -3 ) e porosidade (43,3%) foram observados para a madeira tratada em temperatura de 200 °C. As perdas de massa foram crescentes com o aumento da temperatura e os maiores valores foram observados na condição de 200 °C (9,3%). A LS e o AF não foram afetados pelos tratamentos térmicos. Os valores médios para RS (3,1%), TS (5,1%) e VS (9,1%) foram reduzidos após a realização dos tratamentos térmicos nas temperaturas de 180°C e 200 °C, que não diferiram entre si. Os tratamentos térmicos foram capazes de diminuir a instabilidade dimensional da madeira de Buchenavia sp. Os tratamentos térmicos potencializam o uso de madeiras da Amazônia de menor prestígio no mercado no contexto da construção civil.

Abstract This work aimed to evaluate the effect of heat treatment on the physical properties of wood from Buchenavia sp. The heat treatments were carried out at temperatures of 180 °C and 200 °C for 2 h. Apparent density (AD), basic density (BD), porosity (Ф), mass loss, longitudinal (LS), radial (RS), tangential (TS) and volumetric (VS) shrinkages and anisotropic factor (AF) were determined. The lowest values of basic density (0.67 g cm-3), apparent density (0.77 gcm-3), and porosity (43.3%) were observed for the wood treated at a temperature of 200 °C. Mass losses increased with increasing temperature and the highest values were observed under the condition of 200 °C (9.3%). The LS and AF was not affected by heat treatments. The mean values for RS (3.1%), TS (5.1%), and VS (9.1%) were reduced after the performance of heat treatments at temperatures of 180°C and 200°C, which did not differ from each other. The thermal treatments were able to reduce the dimensional instability of Buchenavia sp. Thermal treatments enhance the use of less prestigious Amazonian woods in the civil construction market.

ABSTRACT Thermal treatment can modify undesirable characteristics of some woods, dimensional instability, and excessive water adsorption. The present research work aimed to assess the effect of thermal treatment on the physical properties of clone GG100 Eucalyptus wood. Wood samples were obtained from 9 year-old trees. Samples were subjected to three types of thermal treatment (T1, T2, and T3). In T1, the wood was kept in a laboratory kiln at 100 °C for 180 min. In T2, hydrothermal treatment was performed in an autoclave at 120 °C for 120 min. In T3, the combined autoclave and laboratory kiln treatments were employed. The properties evaluated were apparent density (ρa); mass loss (ML); longitudinal (βl), radial (βr), tangential (βt), and volumetric shrinkage (βv); anisotropic factor; and equilibrium moisture content. The treatments caused a decrease of ρa and increase of ML. The Equilibrium Moisture Content (EMC) was lowest for T3, and had a negative correlation with ML, βt, and ∆v. The Pearson correlation analysis indicated the results of the thermal treatments were similar, but T1 presented the lowest variation of the physical properties compared to the other treatments, giving it the best predictability for practical uses.

RESUMO Os sistemas agroflorestais (SAFs) integram, com práticas sustentáveis, culturas agrícolas e florestais para produção de madeira e alimentos, conservando os serviços ambientais e a biodiversidade. O freijó, Cordia goeldiana, tem potencial para cultivo na Amazônia para fins madeireiros, porém dados sobre as características de sua madeira em SAFs são escassas. Objetivou-se determinar as propriedades físico-mecânicas e aplicações tecnológicas da madeira de freijó produzida em um SAF multiestratificado estabelecido no estado de Rondônia, Brasil em 1996. No SAF, as espécies agrícolas e madeireiras foram estabelecidas em renques duplos no espaçamento 5,0 m x 2,5 m. Abateram-se três árvores de freijó com 19 anos de idade, para caracterização química, física (densidade e estabilidade dimensional) e mecânica (compressão, flexão estática, dureza Janka e cisalhamento) da madeira. A madeira de freijó apresentou composição química similar à de madeiras nobres tropicais, peso moderado (582,63 kg m-3) e estabilidade dimensional elevada em comparação com outras madeiras consagradas no mercado (retração longitudinal, radial e tangencial = 0,25, 4,27 e 6,83%, respectivamente). Os valores de resistência à compressão paralela (32,32 MPa) e perpendicular (8.02 MPa), resistência específica (55,32 MPa kg-1 m-3), dureza Janka paralela (2373,33 N) e perpendicular (2326,67 N), resistência à flexão estática (63,5 MPa) e ao cisalhamento (5,94 MPa) foram semelhantes aos valores observados em outras madeiras tropicais de alta densidade, produzidas em monocultivo e florestas naturais. A madeira em estudo é adequada para fabricação de produtos de alto valor agregado, como móveis finos, pisos residenciais, instrumentos musicais e peças estruturais.

ABSTRACT Agroforestry systems (AFSs) integrate, through sustainable practices, agricultural and forest crops for the production of wood and food, providing environmental services, and conserving biodiversity. The freijó (Cordia goeldiana) has potential for cultivation in the Amazon for timber purposes, but data on the characteristics of its wood produced in AFSs are scarce. Our objective was to determine the physical-mechanical properties and suggest technological applications of freijó wood produced in a multi-stratified AFS established in the state of Rondônia, Brazil in 1996. Agricultural and forest species were established in the AFS in double rows with 5.0-m x 2.5-m spacing. Three 19-year-old freijó trees were harvested for chemical, physical (density and dimensional stability), and mechanical (compression, static bending, Janka hardness, and shear strength) characterization of the wood. The wood presented a chemical composition similar to tropical hardwoods, was moderately heavy (582.63 kg m-3), and had high dimensional stability in comparison with other consecrated woods on the market (longitudinal, radial, and tangential retraction = 0.25, 4.27, and 6.83%, respectively). The values determined for parallel (32.32 MPa) and perpendicular compression (8.02 MPa), specific strength (55.32 MPa kg-1 m-3), parallel (2373.33 N) and perpendicular Janka hardness (2326.67 N), strength to static bending (63.5 MPa), and shear (5.94 MPa) were similar to the values observed in other high-density tropical woods grown in either monoculture plantations or natural forests. The wood under study is suitable for manufacture of high-value-added products, such as fine furniture, residential floors, musical instruments and structural pieces.

Resumo Objetivou-se analisar o efeito do tempo e da temperatura de tratamentos térmicos nas propriedades físico-mecânicas da madeira de cambará (Qualea paraensis Ducke). Foram confeccionados corpos de prova de 5 lotes da madeira de cambará submetidos ao tratamento térmico em estufa sob temperaturas de 180 °C e 200 °C e períodos de 2 h e 4 h. Determinouse densidade aparente (ρ12%), perda de massa (PM), umidade de equilíbrio (UE), contrações nos eixos longitudinal (βl), radial (βr) e tangencial (βt), contração volumétrica (βv) e fator anisotrópico (fa). Mecanicamente, a madeira foi avaliada quanto à resistência e rigidez nos ensaios de flexão estática (f M e EM) e compressão paralela às fibras (fc0 e Ec0). Após os tratamentos térmicos, os valores de ρ12% aumentaram, em média, 7,72% e a UE foi reduzida em 24,3%. Os maiores valores de PM (3,67%) foram observados para o tempo de exposição de 2 h em temperatura de 200 °C. Com este tratamento, obtevese também os menores valores de βt (5,73%) e βv (9,69%) . Os tratamentos térmicos aumentaram a densidade aparente, reduziram a umidade de equilíbrio e aumentaram a estabilidade dimensional da madeira. Na maioria dos tratamentos térmicos, observouse redução da resistência e aumento da rigidez à flexão estática. Ocorreu aumento da resistência e da rigidez à compressão paralela à grã em todas as combinações de tempo e temperatura. De modo geral, a maior estabilidade dimensional com menores perdas da resistência à flexão estática e compressão paralela foram obtidas com o tratamento de 200 °C e tempo de 2 h.

Abstract The objective was to analyze the effect of heat treatments on the physical and mechanical properties of Qualea paraensis wood. Test specimens from 5 lots of wood were submitted to heat treatments using temperatures of 180 °C and 200 °C with periods of 2 h and 4 h. Density (ρa), mass loss (PM), equilibrium moisture content (UE), longitudinal (βl), radial (βr) and tangential (βt) shrinkage, volumetric shrinkage (βv) and anisotropic factor (fa) were determined. Mechanically, the wood was evaluated for strength and stiffness in the tests of static bending (fM and EM) and compression parallel to the fibers (f c0 and Ec0) . After the heat treatments, the values of ρ12% increased, on average, by 7.72% and the UE was reduced by 24.3%. The highest values of PM (3.67%) were observed for the exposure time of 2 hours at a temperature of 200 °C. With this treatment, the lowest values of βt (5.73%) and βv (9.69%) were obtained. The thermal treatments increased the bulk density, reduced the equilibrium moisture content, and increased the dimensional stability of the wood. In most heat treatments, a reduction in strength and an increase in stiffness to static bending was observed. There was an increase in strength and stiffness to compression parallel to the grain in all combinations of time and temperature. The greatest dimensional stability with less loss of strength to static bending and parallel compression were obtained with the treatment at 200 °C and time of 2 h.

Resumo Diante da elevada demanda por madeira de qualidade pelo setor florestal e madeireiro, o conhecimento das propriedades de novas espécies florestais torna-se imprescindível para que se tenha um comércio abastecido e diversificado, reduzindo assim, a exploração de um pequeno grupo de espécies em função do desconhecimento das demais. Desta forma, o objetivo deste trabalho foi analisar as propriedades físicas, químicas e de superfície da madeira de quatro espécies da Amazônia. Foram utilizadas amostras de madeira de timborana (Piptadenia suaveolens), pequiá (Caryocar villosum), sucupira amarela (Bowdichia nitida) e maçaranduba (Manilkara huberi). As madeiras foram avaliadas quanto a sua composição química, propriedades físicas (densidade, porosidade, contrações e umidade) e propriedades de superfície (colorimetria e molhabilidade). Na madeira de pequiá obteve-se os maiores percentuais de holocelulose (73,42%), extrativos (5,10%) e cinzas (1,06%). Observou-se que as madeiras de maçaranduba e sucupira amarela foram as mais densas, com valores de densidade aparente de 0,96 e 0,98 g/cm³, respectivamente. Na madeira de timborana registrou-se a maior estabilidade dimensional, obtendo valores de 2,03 (βr), 4,45 (βt) e 7,23 (βv). Já nas propriedades de superfície, conforme os valores dos parâmetros colorimétricos, as madeiras classificaram-se como rosa-acinzentado (timborana), oliva-amarelado (pequiá), oliva (sucupira amarela) e marrom-escuro (maçaranduba). Com relação a molhabilidade, verificou-se redução do ângulo de contato da água de 5 s para 10 s, em ambas as madeiras e planos. E constatou-se que as madeiras timborana diferiram estatisticamente quando se analisou o ângulo de contato em relação à face da madeira e o tempo. Assim, as madeiras tropicais avaliadas apresentaram propriedades relevantes para aplicações diversas no comércio madeireiro.

Abstract The high demand for quality wood by the forestry and timber sector, the knowledge of the properties of new forest species becomes essential to have a stocked and diversified trade, thus reducing the exploitation of a small group of species due to the unfamiliarity of the other species. Thus, the objective of this work was to analyze the physical, chemical, and surface properties of the wood of four species of the Amazon. Samples of timborana (Piptadenia suaveolens), pequiá (Caryocar villosum), sucupira (Bowdichia nitida) and maçaranduba (Manilkara huberi) were obtained. The wood was evaluated for their chemical constitution, physical properties (density, porosity, shrinkage, and moisture content) and surface properties (color and wettability). The highest percentage of holocellulose (73,42%), extracts (5,10%) and ashes (1,06%) were obtained in the pequiá wood. It was observed that the maçaranduba and sucupira were the densest, with apparent density values of 0,96 and 0,98 g/cm³, respectively. In timborana wood the greatest dimensional stability was registered, obtaining values of 2,03 (βr), 4,45 (βt) and 7,23 (βv). In the surface properties, according to the values of the colorimetric parameters, the woods were classified as pinkish gray (timborana), yellowish olive (pequiá), olive (sucupira) and dark brown (maçaranduba). Regarding wettability, there was a reduction in the water contact angle from 5 s to 10 s, in both wood and planes. And it was found that the timborana woods differed statistically when the contact angle in relation to the face of the wood and the time was analyzed. Thus, the tropical woods evaluated presented relevant properties for various applications in the timber trade.