No abstract

http://dx.doi.org/10.5902/198050985737O lenho juvenil apresenta grande diferença em suas propriedades anatômicas e físicas em relação ao lenho adulto. Essa heterogeneidade da madeira causa uma série de transtornos para a indústria de transformação e processamento. O presente trabalho teve como objetivo o estudo das propriedades físicas dos lenhos juvenil e adulto de Pinus elliottii Engelm var. elliottii, com 25 anos de idade, e de Eucalyptus grandis Hill ex Maiden, com 30 anos de idade, provenientes da Estação Experimental de Itapetininga e da Floresta Estadual de Santa Bárbara, pertencentes ao Instituto Florestal do Estado de São Paulo. Para tanto, de ambas as espécies, foram retirados, de tábuas radiais, corpos de prova com dimensões de 20x30x50 mm, para a determinação das massas específicas, dos inchamentos e dos coeficientes de retratibilidade dos lenhos juvenil e adulto. Os resultados das espécies mostraram que os lenhos adultos comparados com os lenhos juvenis apresentaram: (1) um aumento nos valores das massas específicas básica, a 0% e a 12% de umidade, dos inchamentos volumétricos e lineares tangencial e radial a 12% de umidade e máximos, e dos coeficientes de retratibilidade tangencial e radial; (2) uma redução nos valores de inchamentos lineares longitudinais a 12% de umidade e máximos, e do coeficiente de retratibilidade longitudinal.

The objective of this study was to evaluate the effect of log steaming and steaming prior to drying singly and both treatments together on the drying behavior and decay resistance of Hevea brasiliensis wood (rubberwood). Logs with a diameter of 34.6 � 4.4 cm were used. Half of the logs were kept in their original condition, and the other half were steamed at 90°C for 36 h. Later, the logs were cut into flat sawn boards. Half of the boards were kept in their original condition, and the other half were presteamed at 90°C for 3 h after 1 h of heating-up. These boards were dried in a drying kiln. The drying defects, drying time, drying rate, and decay resistance of wood to the Pycnoporus sanguineus fungus were determined. The results showed that the steaming is not suitable for decreases in the time and the drying rates of this kind of wood, and it neither reduces the drying defects of boards. Furthermore, these treatments adversely affected the decay resistance of rubberwood to P. sanguineus fungi.

This study aimed to evaluate the effect of log steaming on the physical properties of Eucalyptus grandis Hill ex Maiden wood. Logs with diameters between 20 and 25 cm and length of 2.9 m were studied. Half the logs were maintained in their original condition, and the other half were steamed at 90 °C for 20 hours. Later, the logs were sawn into flat boards, and samples were removed to determine the physical properties of the wood. The results showed that log steaming caused a significant decreases of: (1) 6.38% and 7.98% in the respective basic and oven dried density; and (2) 7.20%, 7.80%, 5.13%, and 8.56% in the volumetric, tangential, radial, and axial linear swelling of wood.