ResumenEste trabajo tuvo por objetivo determinar las propiedades físicas y mecánicas, así como el comportamiento en distintos procesos industriales, de maderas de las especies: paraíso (Melia azederach), kiri (Paulonia tomentosa), toona (Toona ciliata) y grevillea (Grevillea robusta), cultivadas en la Provincia de Misiones, Argentina. Las propiedades estudiadas fueron peso específico, contracción total, coeficiente de retractabilidad, anisotropía de contracción y flexión estática, bajo las Normas IRAM N° 9544, 9543 y DIN N° 52186. Grevillea, paraíso, toona y kiri presentaron valores medios de pesos específicos aparente de 0,530 g/cm³; 0,600 g/cm³; 0,422 g/cm³ y 0,270 g/cm³ respectivamente. La contracción total en la dirección tangencial de las maderas de paraíso, toona, grevillea y kiri presentaron los valores de 6,82 %; 7,85 %; 5,69 % y 4,51 % respectivamente; en la dirección radial de las mismas maderas presentaron los valores de 5,44 %; 4,11 %; 3,5 % y 1,57 % respectivamente. La madera de paraíso fue la que presentó valores superiores de módulos de rotura y elasticidad 852,89 kg/cm² y 72505 kg/cm², respectivamente. La grevillea presentó valores menores con respecto al paraíso tanto en el módulo de rotura como en el módulo de elasticidad, 521,55 kg/cm² y 45693 kg/cm² respectivamente. La madera de toona presentó un valor medio del módulo de rotura y elasticidad de 468 kg/cm² y 65118 kg/cm², respectivamente. La madera de kiri, como es de esperar, arrojó valores de los módulos de rotura de 256,85 kg/cm² y elasticidad a la flexión estática 25261,52 kg/cm², menores que las especies ya citadas. El rendimiento en el proceso de aserrado de las maderas fue: kiri, 50%; grevillea, 48%; toona, 50% y paraíso, 55%. Palabras-clave: Características tecnológicas; especies forestales; muebles; calidad. Abstract Study of the physical and mechanical properties of timber from Melia azederach, Paulonia tomentosa, Grevillea robusta and Toona ciliata, and of its behaviour when it is converted to lumber.The aim of this work was to determine the physical and mechanical properties of the timber from Melia azederach, Paulonia tomentosa, Grevillea robusta and Toona ciliata, cultivated in the Alto Parana region of Argentina, and the behaviour when used as indoors and outdoors furniture. Specific gravity, total contraction, coefficient of retractability, contraction anisotropy, and static flexion (static bending) were studied by IRAM normalisation protocols number 9544, 9543 and DIN protocol number 52186. The mean values of the apparent specific gravity of grevillea, paraiso and toona., were 0,530 g/cm³, 0,600 g/cm³, 0,422 g/cm³, in that order and 0,270 g/cm³for Kiri. Total contraction in the tangential direction in the lumber of paraiso, toona, kiri and grevillea storned value of 6,82 %; 7,85 %; 5,69 % and 4,51 % respectiveley. In the radial direction the values were 5,44 %; 4,11 %; 3,5 % y 1,57 % respectiveley Evaluation of mechanical properties: paraiso (modulus of rupture: 852,59 kg/cm²; modulus of elasticity: 72505 kg/cm²); Kiri (modul...

ResumenEl objetivo del trabajo fue estudiar el comportamiento de la madera de Pinus taeda L. sin impregnar e impregnada con CCA tipo C, con retenciones de 5, 10 y 15 kg/m 3 , frente a la acción de los hongos xilófagos, Pycnoporus sanguineus, Laetiporus sulphureus, Plerotus sajor caju, Ganoderma applanatum, Glophyllum sp. en ensayos de laboratorio. Las maderas fueron obtenidas de seis árboles seleccionados al azar, e impregnadas con CCA en una autoclave de laboratorio. Para determinar la eficacia del preservante fueron utilizadas, 5 probetas de 3 x 1 x 0,5 cm por retención y por cepa de hongos y 5 de madera sin impregnar, testigo. Las probetass fueron puestas en ambiente de laboratorio para climatización y fueron pesadas. Los hongos fueron cultivados en tubos de ensayos de 20 mm de diámetro y 200 mm de largo, y sobre los mismos se colocaron las probetas, permaneciendo en estufa a 28 ºC por 12 semanas. Luego de este período las probetas fueron retiradas y puestas en ambiente de laboratorio, hasta obtener el contenido de humedad del inicio del ensayo. La degradación fue evaluada a través de la pérdida de peso. La madera de Pinus taeda L. fue moderadamente resistente con retenciones de 5 y 10 kg/m 3 de CCA, por lo tanto la retención de 5 kg/m 3 es suficiente. Palabras claves: Pinus taeda; CCA; durabilidad; hongos xilófagos. Abstract Durability of Pinus taeda L. wood, impregnated with chromated copper arsenate to the xylophagaus fungi action. Misiones, Argentina.The objective of this work was to study the behavior of Pinus taeda L. wood without and with impregnation with retentions of 5, 10 and 15 kg/m 3 of chromated copper arsenate, type C, preservative against Pycnoporus sanguineus, Laetiporus sulphureus, Plerotus sajor caju, Ganoderma applanatum, Glophyllum sp. in laboratory conditions. The wood was obtained from six trees chosen at random, and impregnated with C.C.A. in laboratory autoclave. To determine the efficiency of preservative 5 samples were used 5 samples of 3x 1 x 0,5 cm of no treated wood, were used. The wood samples were sterilized and put on a xylophagaus fungi staying in oven at 28°C for 12 weeks; after this period, the samples were taken away and put on a laboratory environment, until the moisture content of the beginning of the experiment was attained. The degradation was evaluated through the weight loss. The Pinus taeda L. wood was moderately resistant with retentions of 5 and 10 kg/m 3 of CCA, therefore retention of 5 kg/m 3 is enough.

Este trabajo tuvo por objetivo, estudiar el comportamiento de las propiedades físicas y mecánicas de la madera de Pinus taeda L. impregnada por vacío-presión con preservador CCA (CrO3; CuO; As2O5) con tres retenciones, 5, 10 y 15 kg/m3. El proceso de impregnado se realizó, por el método Burnett, aplicándose presión y vacío de 7 kg/m2 y – 0,5 kg/m2 respectivamente. Los ensayos de las propiedades físicas y mecánicas se determinaron según lo establecen, las Normas técnicas IRAM (Instituto Argentino de Racionalización de Materiales), ASTM (American Society for Testing and Materials) y DIN (Deutsche Industrie Norm). Las propiedades físicas como ser los pesos específicos aparentes no son afectadas por las retenciones de CCA en la madera. Las contracciones tanto en el sentido tangencial como radial en las maderas impregnadas son menores. Las propiedades mecánicas de resistencia a la flexión estática, compresión paralela a las fibras, tracción perpendicular a las fibras, disminuyen levemente sus valores promedios con respecto a la madera sin impregnar, pero estas diferencias no son estadísticamente significativas, para 95 % de confianza. La impregnación ha producido un efecto positivo en la dureza Janka transversal y en el corte paralelo a las fibras tangencial siendo estas diferencias estadísticamente significativas. Behaviour of the wood of Pinus taeda impregnated with Chrome, Copper, Arsenic (CCA) Abstract The physical and mechanical properties of the wood of Pinus taeda L. without impregnating and impregnating by empty - pressure with preserving CCA (Chrome, Copper, Arsenic) with three retentions, 5, 10 and 15 kg/m3 have been determined and analysed. The impregnation was accomplished in an autoclave applying the Burnett method. The physical and mechanical properties were determined according to the following technical Procedures; IRAM (Argentine Institute for Rationalization of materials), ASTM (American Society for Testing and Material) and DIN (Deutsche Industrie Norm). The results indicate that the specific weights of samples containing different percentages of humidity was not affected by the retentions of CCA in the wood. The shrinkage both in the tangential and radial directions in the impregnated samples were smaller in the impregnated sample. The mechanical resistance to statics flexion, compression parallel to the fibers, traction perpendicular to the fibers, hardness tangential and radial Janka and paralell radial cut, do not show statistically meaningful differences between impregnated and not impregnated samples; however the treatment has produced a positive effect in the hardness transverse Janka and in the parallel cut to the tangential fibers.

Wood density (WD) and other wood mechanical and structural properties may have a strong functional relationship with demographic patterns and allometry of trees. We analyzed the influence of WD, structural properties, architectural traits and community level attributes on growth rates (GR) and mortality modes of canopy tree species in a subtropical forest of Argentina. Stem WD, and WD, strength, stiffness, toughness and hardness of branches were measured in 10 canopy species. Also, architectural traits and liana load were determined. Strength and hardness of branches were linearly correlated to branch WD, and GR were linearly correlated to stem WD across species. At individual level, trees with greater hardness and toughness in branches died mostly uprooted and trees with greater branch stiffness and susceptibility to colonization by lianas were mostly broken. At community level, the suppressed trees died mostly broken. The dominant trees with high local tree density died mostly broken whereas more isolated trees died mostly uprooted. Mortality modes were determined by mechanical properties, but also by community properties, such as liana load, crown canopy position and number of neighboring trees. Other biophysical traits beside WD are important explanatory variables when dry wood is used to describe functional characteristics of trees.

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High-value products can be obtained from non-traditional lignocellulosic resources, such as bamboo, taking full advantage of these materials through efficient, low-cost and low-pollution fractionation processes. This work aims to analyze the physical, chemical, and morphological differences between two bamboo species as a rapidly growing resource of great regional interest – Guadua trinii and Guadua angustifolia. Both samples were characterized in terms of basic density, morphological characteristics, and chemical composition. This work shows that G. trinii has a significantly denser woody structure, with a uniform density at the sampled culm height. The internal structure consists of a parenchyma matrix and vascular bundles composed of parenchyma cells and fiber bundles. G. angustifolia has significantly longer fibers. Chemical characterization showed differences between the carbohydrate and lignin contents. The results of this work are critical to know the potential of both bamboo species as a source of high-value products in the bamboo biorefinery framework.