ABSTRACT Background: Boiling, steaming, and microwave radiation treatments were used for softening and then manufacturing curved samples using three Brazilian hardwoods. Solid wood samples from Carya illinoinensis, Luehea divaricata and Platanus x acerifolia were characterized for bending quality, bending defects, minimum radius of bending, spring-back and moisture content. Results: Among the studied woods, Carya illinoinensis wood was the most suitable to conform curved samples since 96.7% of these wood samples reached a perfect curved shape. On the other hand, Luehea divaricata wood presented the worst behaviour, which was marked by only 36.7% of samples achieving a perfect shape. In general, the studied hydrothermal treatments and exposure times induced similar softening behaviours. Conclusion: In this sense, microwave heating seems to be a good option when compared to the other pathways, since it is known that this method require low consumptions of both time and energy.

Abstract: This study aims to evaluate chemical characteristics, antioxidant and antibacterial activities of organic compounds extracted from three Eucalyptus wood and Corymbia maculate wood using ethanol as a solvent. To obtain the ethanolic extracts, 15 g of a powdered wood sample was mixed with 150 mL of ethyl alcohol 99 % PA by constant mechanical stirring, which was further magnetically mixed at 60 ºC for 24 h. The extractives were analyzed utilizing percent yield, Fourier-transform infrared spectrum, inhibitory index (measured after antimicrobial tests), antioxidant activity, and condensed tannins content. The Eucalyptus dunnii extract showed the highest percent yield. The infrared spectra of all the extractives presented similar profiles, with remarkable bands ascribed to the presence of lipophilic extracts, sterols, fatty acids, and other hydroxylated substances, such as carbohydrates and phenolic compounds. In all cases, the higher the concentration of the extractive was, the higher the antioxidant activity was. The antioxidant activity of Eucalyptus saligna extract stood out since overcame that of the positive control (ascorbic acid). Regarding the condensed tannins content, that extract from Eucalyptus grandis excelled.

Abstract: In the present study, three juvenile hardwoods (namely sycamore, pecan and london plane) were treated by boiling, steaming and microwave. Trees from Platanus x acerifolia (sycamore), Carya illinoinensis (pecan) and Luehea divaricata (london plane) were selected in homogeneous forests located in southern Brazil. Each hydrothermal treatment was performed for 60 min. In general, the hydrothermal treatments caused a certain surface inactivation effect, which was marked by decreased surface roughness, increased hydrophobic character and darkened colour patterns. Also, both decreased stiffness and strength, as well as increased deflectibility were obtained. These mechanisms were attributed to degradation in fine segments from amorphous polysaccharides, leaching of some organic extractives and fragmentation of lignin, as indirectly indicated by infrared spectra.

Abstract: Organic substances have been used for different wood treatments, especially impregnation procedures, aiming at improve certain wood properties. The objective of this study was to evaluate dimensional stability and colourimetric features for a mature pine wood (Pinus elliottii) impregnated by vacuum-pressure process with variable concentrations (10 wt%, 25 wt% and 50 wt%) of furfuryl alcohol and using ethyl alcohol as catalyst. The wood samples were characterized for:linear shrinkages, linear swellings, shrinkage anisotropy, swelling anisotropy, as well as colorimetric parameters (following the CIELab method). The impregnation with furfuryl alcohol increased the dimensional stability of the studied pine wood and the treatment with a concentration of 50 wt% stood out based on these results. Regarding the colourpatterns, there were changes in the final colorimetric appearances of the treated wood samples, which acquired darker and reddish colours when compared to the pristine group. The treatment with 50 wt% of furfuryl alcohol also was responsible for the highest colour change and, because of that, may be indicated for solid wood products with high added value.

RESUMO Nesse estudo foram feitas correlações entre composição química e estabilidade dimensional das madeiras de Eucalyptus botryoides. Eucalyptus paniculata e Eucalyptus tereticornis. Para isso, foram confeccionados corpos de prova em cinco diferentes posições ao longo do perfil radial, correspondentes a 0, 25, 50, 75 e 100% de distância da medula. Para a análise física, os corpos de prova foram submersos em água até a saturação, condicionados sob temperatura de 20°C com umidade relativa (UR) de 65% e secos em estufa (103 ± 2°C). Foram coletados dados de massa e dimensões desses corpos de prova em cada uma dessas etapas, para posterior cálculo da densidade aparente a 12% e das contrações tangencial, radial e volumétrica. Para as análises químicas, amostras referentes a cada posição foram caracterizadas por meio dos teores de extrativos solúveis em etanol-tolueno, lignina Klason, hemicelulose e α-celulose. Observou-se que as madeiras dos três eucaliptos apresentaram comportamento similar. O percentual de lignina e a densidade básica apresentaram correlação positiva, ambos aumentando no sentido medula-casca, enquanto a hemicelulose correlacionou-se negativamente com a densidade e o percentual de extrativos negativamente com os parâmetros de retratibilidade.

ABSTRACT In this study correlations between chemical composition and dimensional stability of Eucalyptus botryoides. Eucalyptus paniculata e Eucalyptus tereticornis were evaluated. Specimens were prepared from five different positions in radial direction, corresponding to 0, 25, 50, 75 e 100%, from pith to bark. For physical analysis, samples mass and dimensions were measured above saturation point, at conditioned temperature (20°C and 65% of relative humidity) and oven dried (103 ± 2°C). In each step density at 12% (ρb), as well tangential (βT), radial (βR) and volumetric (βV) shrinkage were calculated. Samples from same positions were chemical evaluated concerning to soluble extractives in ethanol-toluene, insoluble lignin, hemicellulose and α-cellulose. It has been observed similar behavior among eucalypt wood. Lignin and density showed positive correlation, both increasing from pith to bark, while hemicellulose presented negative correlation with density and extractives negative correlation with shrinkage.

RESUMO Usinas vêm utilizando biomassas de base florestal para a produção de energia térmica e elétrica. Nada obstante, essas industriais carecem de parâmetros confiáveis sobre sua matéria prima, afim de consolidar sua posição nesse mercado. O presente estudo objetivou caracterizar resíduos florestais provenientes de plantações de pinus (Pinus elliottii) sobressalentes de serrarias. A madeira, a casca e uma mistura de ambas foram caracterizadas por análises químicas imediata (Teores de umidade total, umidade de higroscopia, cinzas, matérias voláteis e carbono fixo), elementar (Teores de S, C, H, Ni e [O + Halogênios]), via úmida (Teores de holocelulose, lignina e extrativos). Adicionalmente, densidade e propriedades energéticas (poderes caloríficos superior e inferior) também foram determinados. A casca apresentou maior teor de extrativos comparada a madeira, o que afetou o teor de cinzas. Em relação as propriedades energéticas, a casca apresentou as maiores propriedades, embora também um caráter depreciativo do ponto de ambiental. A mistura madeira-casca apresentou propriedades intermediárias entre esses dois resíduos, embora mais aproximadas às da madeira.

ABSTRACT Power plants have been using forestry biomasses to produce thermal and electrical energies. However, these industries lack of reliable parameters about their raw material in order to consolidate their position in this market. The present study aimed to characterize forestry wastes from pine (Pinus elliottii) plantations leftover of wood logs processing units. Wood, bark and a mixture of both of them were characterized by prompt (total moisture, hygroscopic moisture, ashes, volatile matter and fixed carbon contents), elementary (S, C, H, N and [O + Halogens] contents), and via wet (holocellulose, lignin and extractives contents) chemical analyses. Indeed, basic density and fuel properties (gross and net calorific values) were also determined. Compared to the wood, the bark presented higher extractives content, which affected the ashes content. Regarding the energetic properties, the bark showed the highest properties, but a detrimental character from an environmental standpoint. The wood-bark mixture presented intermediate properties between these two forestry wastes, but with more approximation to the wood.

RESUMO O presente estudo objetivou estimar as tensões de crescimento da madeira de clones de Eucalyptus spp., por meio de algumas de suas propriedades dendrométricas, utilizando-se de variáveis Dummy. Foram selecionados 12 clones híbridos do gênero Eucalyptus, dos quais foram avaliadas as propriedades dendrométricas: diâmetro a altura do peito (DAP), espessura de casca (EC), altura (H), volume total (VOL); bem como a densidade básica (DB). As tensões de crescimento foram avaliadas de maneira indireta, por meio da deformação residual longitudinal (DRL), medida conforme o método CIRAD-Forêt. Foram definidas 12 variáveis Dummy com base nas características de cada clone. Após, a fim de estimar matematicamente a DRL, foram propostos quatro modelos utilizando-se como variáveis independentes: DAP, H, VOL, DB e as variáveis Dummy. Dentre as propriedades dendrométricas, a DB foi a única descartada por não aportar subsídios interessantes para a predição da DRL. Na comparação entre as variáveis Dummy, o clone 9 deu origem à variável mais discrepante em relação às demais. Contudo, os resultados obtidos indicaram que, embora tenha havido uma variabilidade significativa nos níveis de DRL na comparação entre os diferentes clones, os modelos matemáticos obtidos descreveram satisfatoriamente as tensões de crescimento dos mesmos.

ABSTRACT The evaluation of growth stresses in Eucalyptus trees and their influence on both morphological properties of trees and technological properties of wood have been aimed by several studies, which used indirect and nondestructive methods for these evaluations. The present study aimed to estimate growth stresses for woods from Eucalyptus ssp. clones trough some of their dendrometric properties, using Dummy variables. 12 hybrid Eucalyptus clones were evaluated by basic density (BD) and dendrometric properties: diameter at breast height (DBH), bark thickness (BT), height (H) and total volume (VOL). The growth stresses were indirectly evaluated by the longitudinal residual strain (LRS) following the CIRAD-Forêt method. 12 Dummy variables were defined based on the characteristics of each clone. After that, four models were proposed in order to estimate the LRD, using Dummy variables, DBH, H, VOL and BD as independent variables. Among the dendrometric properties, BD was discarded because it does not confer interesting aids to the LRD predict. Among the Dummy variables, clone 9 provided the most discrepant variable. The LRD of the clones were satisfactorily described by the mathematical models, although these values showed significant variability.

Surface degradation in outdoor wood and products is due to a combination of inherent climate factors together with colonization of decay organisms. From a technical and economic standpoint it is one of the main problems for the industry of products and materials made from wood. The aim of this work is to track the surface degradation of Corymbia citriodora and Eucalyptus tereticornis timbers originating from fast-growing plantations in Brazil, which have been exposed to outdoor weathering tests in three different environmental conditions. Changes in the material were monitoring using color measurement (CIEL*a*b* method), in cycles of 45 days up to a period of 360 days of exposure. The results showed that timber exposed to a forest ecosystem was less affected by environmental factors; this is probably due to climate insulation provided by these ecosystems. Besides, it was observed that samples of Corymbia citriodora had higher resistance to degradation compared with samples of Eucalyptus tereticornis, possibly due to differences in its chemical constitution.

La degradación superficial en madera de exteriores se debe a una combinación de factores meteorológicos inherentes al entorno de exposición y a la colonización de organismos xilófagos. Desde un punto de vista técnico y económico se trata de uno de los principales problemas para la industria de productos y materiales hechos a partir de la madera. El objetivo del presente trabajo es el de monitorizar la degradación superficial de las maderas de Corymbia citriodora y Eucalyptus tereticornis originarias de plantaciones de rápido crecimiento de Brasil, las cuales han sido expuestas a ensayos de intemperismo natural en tres entornos ambientales distintos. La monitorización de los cambios en el material fue realizada mediante estimaciones del color (método CIEL*a*b*), en ciclos de 45 días, hasta completar un periodo de 360 días de exposición. Los resultados mostraron que el material expuesto al entorno forestal fue menos afectado por los factores ambientales, lo que ha sido probablemente debido al aislamiento térmico y solar que proporciona este tipo de ecosistema. A su vez, se observó que las probetas de madera de Corymbia citriodora presentaron mayor resistencia al deterioro que las probetas de madera de Eucalyptus tereticornis, posiblemente debido a ciertas diferencias en su constitución química.

The evaluation of wood durability enables the definition of reliable parameters to predict the service-life of wood-based products. This study aimed to evaluate the wood deterioration of four fast-growing eucalypts species (Eucalyptus botryoides, Corymbia citriodora, Eucalyptus paniculata e Eucalyptus tereticornis) exposed to three field tests (outdoor, flooded site and forest canopy) during 540 days. The physical properties measured were: mass loss, density and moisture content. Furthermore, we determined changes in wood color by CIEL*a*b* method and performed a visual analysis by CEN grades. Among the four wood eucalypts, Eucalyptus tereticornis presented the highest decay resistance. The flooded site presented the best conditions for the proliferation of xylophagous agents. Mature wood was least susceptible to deterioration than juvenile wood.

RESUMO Em vista da crescente utilização da madeira de eucalipto no setor industrial e da frequência com que ocorrem defeitos de crescimento e secagem, se devem ao fator espécie. O presente estudo objetivou analisar características tecnológicas da madeira de clones do gênero Eucalyptus. Foram selecionados 29 clones aos três e sete anos de idade no município de Tapes, Rio Grande do Sul. Nas árvores em pé e vivas, foi avaliada a deformação residual longitudinal (DRL) por meio de extensômetro CIRAD - Forêt, bem como a velocidade de propagação de ondas de ultrassom (Vsom), parâmetros os quais originaram resultados de Tensão de Crescimento Longitudinal (TCL). Foram confeccionados corpos de prova para a avaliação das propriedades físicas da madeira como: massa específica básica e básica ponderada e velocidade de propagação de ondas de ultrassom. Também propriedades mecânicas de resistência e rigidez, obtidas pelos ensaios de flexão estática, compressão paralela às fibras, cisalhamento e dureza Janka, sendo que para os ensaios de propagação de onda ultrassonora e de flexão estática, foram propostos dois teores de umidades distintos (12% e umidade de saturação). Foram calculados os módulos de elasticidade dinâmicos pela técnica ultrassonora para as duas condições de umidade, sendo que os parâmetros mecânicos avaliados na condição de saturação também foram empregados no cálculo da tensão de crescimento longitudinal (TCL1 e TCL2). Em relação à massa especifica e às propriedades mecânicas, destacaram-se os clones 1 (Eucalyptus urophylla x Eucalyptus maidenii), 23 (Eucalyptus saligna x Eucalyptus saligna) e 24 (Eucalyptus saligna x Eucalyptus saligna). Já do ponto de vista dos níveis de DRL, ressaltaram-se os clones 68 (Eucalyptus urophylla x Eucalyptus globulus) e 72 (Eucalyptus urophylla x Eucalyptus globulus), os quais podem ser indicados para o melhoramento genético tendo em vista à propensão a incidência de defeitos oriundos das tensões de crescimento.

ABSTRACT With the increasing use of eucalypt wood in the industrial sector and against the high occurrence of growth defects and drying, which are due to the specie factor. The present study aimed to analyze technological characteristics of clones from Eucalyptus genus. 29 clones with three and seven years were selected in Tapes, state of Rio Grande do Sul. Longitudinal residual strain (LRS) in standing and vivid trees was evaluated using an extensometer CIRAD - Forêt and an ultrasound to obtain the velocity of propagation of ultrasound waves (Vsom), parameters that were used to determine longitudinal growth stress (LGS). Samples were prepared to determine the physical properties: basic specific gravity, weighed basic specific gravity and velocity of propagation of ultrasound waves. Strength and stiffness at static bending, compression parallel to the grain and Janka hardness tests were determined. Two different levels of moisture content (12% and saturation) for ultrasound and static bending tests e testing were proposed. Dynamic modulus of elasticity by ultrasound technique were determined for the two moisture conditions; and the mechanical parameters evaluated at saturation condition were also used in the determination of the longitudinal growth stress (LGS1 and LGS2). Regarding to the specific gravity and mechanical properties, the highlights were clone 1 (Eucalyptus urophylla x Eucalyptus maidenii), clone 23 (Eucalyptus saligna x Eucalyptus saligna) and clone 24 (Eucalyptus saligna x Eucalyptus saligna). From the point of view of the levels of DRL, clone 68 (Eucalyptus urophylla x Eucalyptus globulus) and clone 72 (Eucalyptus urophylla x Eucalyptus globulus) may be suitable for breeding due to the tendency of the incidence of defects from the growth stresses.

O presente trabalho apresenta a obtenção de maior flexibilidade e elasticidade de uma matriz de cimento Portland de alta resistência inicial (CPV) adquirida a partir da adição de fibras de eucalipto puras e tratadas com tetraetilortossilicato TEOS 98%. As fibras utilizadas foram caracterizadas quanto à morfologia, através de microscopia óptica e com o emprego do software Anatomic MIPro, e quanto à absorção de água, para a verificação da eficiência da impregnação do TEOS 98%. Para a obtenção dos compósitos foram formuladas massas de cimento com adição de fibras de eucalipto puras e tratadas nos teores de 2%, 5% e 10% em massa. Os compósitos foram caracterizados quanto a absorção de água, porosidade aparente e módulo de elasticidade (MOE) a partir da resistência à flexão a três pontos. A análise foi comparativa entre os compósitos de cimento-fibras de eucalipto e uma massa pura de cimento Portland de alta resistência inicial. Os resultados mostraram que os maiores valores de reforço foram obtidos no compósito aditivado com 2% de fibra de eucalipto tratada com TEOS 98%, visto que neste se obtiveram os maiores MOE, caracterizando maior controle de fissuras e de absorção de energia após a fratura da matriz de cimento.

This paper presents the attainment of higher flexibility and elasticity in a high initial strength (CPV) Portland cement matrix, achieved through the addition of pure eucalyptus fibers treated with tetraethylorthosilicate TEOS 98%. The fibers used were characterized by their morphology through optical microscopy and through the use of anatomic MIPRO software; its water absorption properties were analysed using the TEOS 98% impregnation efficiency test. In order to obtain the composites, cement masses were formulated with the addition of pure eucalyptus fibers and treated at concentrations of 2%, 5% and 10% by weight. The composites were characterised for water absorption, porosity, and modulus of elasticity (MOE), measuring their flexural strength at three points. A comparative analysis was done between the cement-eucayptus fiber composite and a high initial resistance Portland cement mass. The results showed that the highest valores de reforço were achieved in the cement with 2% eucalyptus fiber treated with 98% TEOS, since that cement presented the highest MOE values, presenting more fissure control and energy absorption after cement matrix fracture.

RESUMOA madeira de acácia-negra tem sido utilizada em nichos que conferem pouco valor agregado à esse material. Diante disso, este trabalho teve como objetivo analisar as deformações residuais longitudinais (DRL) e suas relações com propriedades da madeira de Acacia mearnsii. Para tanto, foram selecionadas 60 árvores em plantios com idades distintas (4 e 7 anos) no Município de Piratini, RS. As características de crescimento avaliadas consistiram em diâmetro à altura do peito (1,3 m; DAP), espessura de casca (EP) e altura comercial (h). As propriedades físicas avaliadas massa específica básica (ρ) e teorde umidade à base seca (Tu). Já o tempo de propagação de onda ultrassonora foi determinado em conformidade com o procedimento NBR 15521. As propriedades mecânicas foram o módulo de elasticidade dinâmico (Ed), bem como as propriedades descritas no procedimento normativo D143-94, através dos ensaios de flexão estática, compressão paralela às fibras e Dureza Janka. ADRLesuas relações com as propriedades da madeira mostraram-se semelhantes aos resultados encontrados na literatura para a madeira de espécies do gênero Eucalyptus. No entanto, em magnitude, tais níveis se mostraram sensivelmente menores, conferindo à madeira de acácia-negra no que se refere a esse parâmetro de qualidade, indicação para a confecção de produtos sólidos.

ABSTRACTThe black wattle wood has been used in niches that confer low value to this material. Therefore, this study aimed to analyze the longitudinal residual strain (LRS) and its relations with Acacia mearnsii de wild wood properties. To achieve this, 60 trees with 4 and 7 years were selected from a forest population located in Piratini, RS. Diameter at breast height (1.3 m; DBH), bark thickness (BT) and commercial height (h) were evaluated. The physical properties evaluated were specific gravity (ρ) and moisture content on dry basis (Tu). The propagation time of ultrasonic wave was determined as described in NBR 15521 and then the dynamic modulus of elasticity (Ed) was measured. The mechanical properties was evaluated according to D143-94 standard by static bending, parallel compression to fibers and Janka hardness tests. The LRS and its relations with the wood properties were similar to the results found in the literature for wood fromEucalyptus species. However, in magnitude, these levels were sensibly lower, givingblack wattleindication to produce solid wood products, when it comes to this quality parameter.

O vergamento de madeira foi utilizado ao longo dos séculos para a produção de objetos grandes, como estruturas de embarcações ou pequenos utensílios. Mesmo com constantes estudos de vergamento, há carência de melhorias de processo e inclusão de madeiras de baixo valor comercial. Assim, o presente trabalho analisou a madeira vergada de Eucalyptus grandis tratada por diferentes tempos de exposição à vaporização e ao cozimento. Foram analisados o número de tipos de defeitos por peça vergada (Nºdef), a variação no teor de umidade perante os tratamentos (∆Tu), a pressão de extremidade (Pe) e a perda de forma circular (Pf). Verificou-se que as variáveis diferem significativamente entre os tipos de tratamento de vaporização e cozimento, exceto para o Nºdef. Os tempos de tratamento não apresentaram efeito significativo. Concluiu-se que a espécie é aceitável para vergamentos em raios inferiores ao utilizado no presente estudo. Adicionalmente, a vaporização mostrou ser o melhor tratamento, por apresentar melhores parâmetros de qualificação.

Wood bending has been used for centuries in the manufacturing not only of large objects, such as boat structures, but also small objects, like musical instruments. Despite a large number of studies on bending, process improvements and inclusion of low added-value timber are still insufficient. Hence, this study proposes a bent wood analysis of Eucalyptus grandis treated with different steam and boiling exposure times. We analysed the number of failure types per sample (N.of f), moisture content variation in the treatments (∆Tu), end pressure (Pe) and spring back (Pf). The variables showed significant differences between steaming and boiling, except for N.of f. Different treatment times did not show significant effects. We conclude that Eucalyptus grandis timber is suitable for bending at smaller radius than the one adopted in this study. Furthermore, steaming is better than boiling due to its higher qualification parameters.

Diante da importância do conhecimento das respectivas regiões do lenho juvenil e adulto para a indústria de base madeireira, este estudo foi realizado com o objetivo de delimitar, por meio das metodologias de retas de regressão e do incremento anual, as regiões dos lenhos juvenil e adulto das madeiras de açoitacavalo, nogueira-pecã e plátano. O parâmetro anatômico utilizado nas delimitações foi o comprimento de fibra. Adicionalmente, foram medidas outras propriedades anatômicas: diâmetro de fibra, diâmetro de lume e espessura de fibra. As propriedades das fibras foram descritas estatisticamente em razão da diferenciação entre os lenhos proposta em cada metodologia, a fim de comparação. Conforme os métodos das retas de regressão e do incremento anual, as idades de segregação entre os lenhos foram de 21 e 19 anos para a madeira de açoitacavalo e 16 e 14 anos para a madeira de nogueira-pecã. Para a madeira de plátano, ambas as metodologias definiram que o lenho segregou com 14 anos. Pode-se verificar que não houve distinção entre os resultados obtidos com as duas metodologias de delimitação dos lenhos juvenil e adulto, exceto quanto ao comprimento de fibras do lenho juvenil. O método do incremento anual foi considerado preferencial, em razão da fonte de erro verificada no método das retas de regressão.

Before the importance of knowing the respective regions of juvenile and mature wood for the wood industry, this study was conducted with the objective of defining, through methodologies of regression lines and annual increment, the regions of juvenile and mature wood of açoita-cavalo, pecan and sycamore. The anatomical parameter used in the delimitations was fiber length. In addition, others anatomical properties were measured: fiber diameter, lumen diameter and fiber thickness. The fiber properties were statistically described according to the difference between woods proposed in each methodology, for comparison purposes. According to methods of regression lines and annual increment, the segregation ages between woods were 21 to 19 years for açoita-cavalo and 16 to 14 years for pecan. For sycamore wood, both methodologies defined that the wood segregated with 14 years. It may be verified that there was no difference between the results obtained with the two delimitation methodologies of juvenile and mature woods, except for fiber length of juvenile wood. The method of annual increment was considered preferred due to the error source verified in the regression lines.

O presente estudo objetivou analisar propriedades físicas da madeira termorretificada de quatro eucaliptos. Dessa maneira, foram selecionadas 20 árvores com aproximadamente 60 anos de idade de Eucalyptus botryoides, Corymbia citriodora, Eucalyptus paniculata e Eucalyptus tereticornis. Foram confeccionadas amostras próximas das regiões da medula e da casca, de modo a caracterizar a seleção dos lenhos juvenil e adulto, respectivamente. As amostras foram climatizadas ao teor de umidade de equilíbrio de 12%, condição inicial para tratamentos de termorretificação conduzidos a 200 °C, durante uma hora. As modificações oriundas da termorretificação proporcionaram um aumento da estabilidade dimensional das madeiras. Dentre as madeiras estudadas, a menos higroscópica foi a madeira adulta de Eucalyptus paniculata, sendo o maior e o menor incremento de estabilidade dimensional conferidos às madeiras de Eucalyptus tereticornis e Corymbia citriodora, respectivamente.

In this study, we aimed to analyze the physical properties of four thermally treated eucalyptuses. To this end, 20 trees (~60 years old) of Eucalyptus botryoides, Corymbia citriodora, Eucalyptus paniculata, and Eucalyptus tereticornis were randomly selected in the municipality of Charqueadas, Rio Grande do Sul state, Brazil. We prepared samples near the pith and bark of trees in order to characterize the selection of juvenile and mature wood, respectively. The samples were kept in a climatic chamber to obtain the equilibrium moisture content (~12%), which was the initial condition for the thermal treatments at 200 °C for 1 hour. Changes due to thermal treatment resulted in an increase in the dimensional stability of wood. Among the eucalyptuses, the lowest hygroscopicity was found for the mature wood of Eucalyptus paniculata, while the highest and the lowest increases of dimensional stability were observed for Eucalyptus tereticornis and Corymbia citriodora wood, respectively.