Magnos Alan Vivian

Qualidade da madeira serrada proveniente de árvores dominantes e médias de Eucalyptus grandis submetidas à secagem

Neste estudo, objetivou-se verificar, em arvores de diâmetro dominante e medio, a influencia da secagem ao ar livre e secagem convencional na qualidade da madeira serrada de um povoamento de Eucalyptus grandis W. Hill ex Maiden, aos 14 anos de idade, situado no municipio de Capivari do Sul, Rio Grande do Sul. Para tanto, a amostragem das arvores foi realizada apos um inventario piloto, tendo como base o diâmetro a altura do peito (DAP) dominante e medio. Apos a derrubada, foi retirada a tora localizada entre as posicoes DAP e 25% da altura comercial. As toras foram desdobradas em tabuas para serem submetidas a secagem ao ar livre ate 18% do teor de umidade, e a secagem convencional foi conduzida ate 13% de umidade. Rachaduras de topo e arqueamento das tabuas foram avaliadas apos o desdobro, na secagem ao ar livre e na secagem convencional. Os resultados mostraram que, tanto para as arvores dominantes quanto para as medias, o indice de rachaduras de topo e a flecha de arqueamento das tabuas nao diferem significativamente nas diferentes fases de processamento da madeira. No entanto, a comparacao entre esses dois estratos evidencia que a magnitude desse defeito e mais pronunciada nas arvores medias.

RESISTÊNCIA BIOLÓGICA DA MADEIRA TRATADA DE Eucalyptus grandis E Eucalyptus cloeziana A FUNGOS APODRECEDORES EM ENSAIOS DE LABORATÓRIO

A presente pesquisa teve por objetivo avaliar a resistencia biologica da madeira tratada de Eucalyptus grandis e Eucalyptus cloeziana sob a acao de organismos biodeterioradores em ensaios de laboratorio. Para tanto, foram utilizadas arvores de Eucalyptus grandis e Eucalyptus cloeziana, ambas com 16 anos de idade, as quais foram desdobradas em tabuas e submetidas ao tratamento preservativo em autoclave com arseniato de cobre cromatado (CCA). Em seguida, confeccionaram-se os corpos de prova para conducao do ensaio de apodrecimento acelerado com os fungos Trametes versicolor e Gloeophyllum trabeum, seguindo as recomendacoes da norma ASTM. A partir dos resultados obtidos, observou-se para o fungo Trametes versicolor que o tratamento preservativo foi eficiente na reducao da degradacao biologica da madeira das duas especies, com reducao da perda de massa em 35,17 e 82,31% para a madeira de Eucalyptus grandis e Eucalyptus cloeziana, respectivamente, ja para o fungo Gloeophyllum trabeum, a perda de massa foi reduzida em 6,79 e 96,65%, em comparacao a testemunha. Com base nas condicoes de realizacao do presente estudo observou-se que o tratamento preservativo com CCA e eficiente no aumento da resistencia biologica da madeira a acao dos fungos apodrecedores Trametes versicolor e Gloeophyllum trabeum.

Hygroscopicity of wood from Eucalyptus grandis and Pinus taeda subjected to thermal treatment

This study aimed to investigate the effect of the thermal treatment technique under two conditions-autoclave combined with electric oven and electric oven only-on the hygroscopic properties of wood from Pinus taeda L. and Eucalyptus grandis W. Hill ex Maiden, comparing them with results obtained for untreated wood. Three trees at age 25 years were sampled, with boards being removed at DBH level in order to make specimens 2.5 x 2.5 x 5.0 cm in size in the radial, tangential and axial direction respectively. In the combined treatment, specimens were subjected to thermal treatment in an autoclave set at 130°C/± 3°C and kgf/cm² pressure for 3 hours, then to a conditioning period, followed by heat in an electric oven set at 160°C/±1°C for the same time. Properties being evaluated included water absorption rate, volumetric swelling, water repellency effectiveness and anti-swelling efficiency. Results revealed that the thermal treatments being adopted were effective in reducing hygroscopicity and in increasing the dimensional stability of both species, revealing also that the combined autoclave and electric oven treatment provides best results.

Effect of eucalyptus wood chips pretreatment with sodium xylenesulphonate (SXS) in the kraft cellulosic pulp quality

This study aimed to evaluate the effect of sodium xylenesulphonate (SXS) application as a pretreatment in wood chips of Eucalyptus grandis x Eucalyptus urophylla in the kraft cellulosic pulp quality. First the wood chemical characterization was made; subsequently the chips underwent a pretreatment in the following conditions: 12 hours, 30% concentration of SXS and temperature of 130oC. After the pretreatment the yield parameters and lignin content remaining in the chips were determined. The pretreated and normal chips (control) were subjected to the kraft pulping process for obtaining a pulp with kappa number 15 ± 0.5; for analyzing the pretreatment effect on the pulp quality. From the results obtained, it was possible to observe that the pretreatment with SXS allowed the extraction of 39.12% of lignin from wood chips, compared with the normal wood. Regarding the pulping process, the pulp yield values obtained from the wood chips pretreated with SXS were lower than the normal chips, but on the other hand showed a high degree of delignification, allowing to obtain pulp with the same kappa number (15 ± 0.5) with active alkali loads 34.8 and 37.6% lower, without and with anthraquinone, respectively, when compared with the normal chips. The addition of anthraquinone increased the screened yield and intensified the pulp delignification rate for the normal chips, not featuring notorious effect for the pretreated chips. The pretreatment with SXS considerably reduced the hexenuronic acids content, and increased the cellulosic pulp viscosity. By analyzing the results obtained from the materials pretreated with sodium xylenesulphonate, it is inferred that the concerned compound is an alternative to the cellulosic industry, because it combines its beneficial characteristics (biodegradable, odorless, non-incrustant, non-corrosive, low volatility, low flammability, easy recovery and high selectivity), to a reduction of reagents consumption in the pulping process, with an improvement in the cellulosic pulp quality.

USO DE Bambusa tuldoides E Eucalyptus grandis PARA CONFECÇÃO DE PAINÉIS AGLOMERADOS

The bamboo panels particleboards can be advantageous when produced with a mixture of some kinds of wood. However, there are few studies using Bambusa tuldoides for the production of homogeneous particleboards or in combination with wood particles. Therefore, the aim of this study was to evaluate the physical-mechanical quality of particleboard made of different percentages of B ambusa tuldoides and E ucalyptus grandis . To do so, 36 panels were produced composed of a mixture of 0, 25, 50, 75 and 100% of dry matter. The tests realized were moisture, mass density, swelling thickness and water absorption. The mechanical tests were bending, internal bond and screw withdrawal (ASTM 1037, 1999). The results submitted to the correlation test and analyzed by regression. The panels did not get the minimum values of the standards (ANSI A 208.1, 1987) for mechanical tests. It is concluded that the homogeneous bamboo panels obtained superior performance in physical tests than the eucalyptus panels, which are usually used in the industrial sector. However, the insertion of bamboo particles impaired the performance of the panels in the mechanical tests.

INFLUÊNCIA DA TERMORRETIFICAÇÃO NA RESISTÊNCIA A DEGRADAÇÃO BIOLÓGICA DAS MADEIRAS DE Pinus taeda E Eucalyptus grandis

This study investigated the effect of two thermal treatment technique on the biological properties of the wood of Pinus taeda L. and Eucalyptus grandis and W. Hill ex Maiden, comparing them with results obtained for the untreated wood. Of each species were sampled three trees at age 25, from where it drew a central plank height DBH for making test specimens were subjected to thermal treatments for later be transformed into pieces of 2.5 x 2.5 x 0.9 cm. In the first treatment the wood were subjected to thermal treatment by autoclaving at 130 oC/ ± 3 ° C and pressure of 2 kgf /cm² for 3 hours and, after a conditioning period, subjected to heat in an electric oven at 160 °C/ ± 1 °C for the same period. The second treatment consisted of only heat treatment by kiln. Resistance to biological attack was evaluated by accelerated decay test in the laboratory, using a white-rot fungus, Trametes versicolor (Linnaeus ex Fries) Pilat and other brown rot Gloeophyllum trabeum (Persoon. ex Fries) Murr. The combined treatment of the autoclave with electric oven favored the decay of both species of wood fungi employees, except for Pinus taeda submitted to the fungus Trametes versicolor , while treatment in an oven provided increase biological resistance of Pinus taeda wood fungus Trametes versicolor and of Eucalyptus grandis fungus Gloeophyllum trabeum . In general it is concluded that treatment in an oven resulted in more resistant to biological degradation and lower weight loss compared with the combined treatment of the autoclave with electric oven when observed the ineffectiveness of thermal treatment while the latter when applied to both species resulted in an increase in the propensity of biological degradation.

EFEITO DA TERMORRETIFICAÇÃO NAS PROPRIEDADES MECÂNICAS DAS MADEIRAS DE Pinus taeda E Eucalyptus grandis

This study investigated the effect of thermal treatment, employed under two treatment conditions on mechanical properties of wood of Pinus taeda L. and Eucalyptus grandis W. Hill ex Maiden. From each species, three 25-year tress were sampled, and from each one, it was taken the first 2-meter long log, which was obtained from two boards of size 7,0 x 20,0 cm (thickness x width respectively) diametrically opposite from where 30 specimens were saw for each treatment. At the first one, called the combined one, the woods were subjected to heat treatment by autoclaving at 130 / ± 3°C and pressure of 2 kgf / cm ² for 3 hours and, after a conditioning period, subjected to heat in an electric oven at 160 / ± 1°C for the same period. The second treatment consisted only of heat treatment in oven. It was also evaluated the pieces of wood without treatment (control). The mechanical properties were evaluated by means of tests for determining the modulus of elasticity and rupture in bending, maximum resistance to compression parallel to the grain and Janka hardness according to ASTM D 143 (1995), and the impact resistance according to ABNT NBR 7190 (1997). For Pinus taeda wood, it was observed that treatment in an oven gave the worst outcomes, both due to the reduction in the values of supported load of a greater number of mechanical properties evaluated, but also as compared to the lowest increments in resistance when it was observed an increase to the same ones with heat treatment. In Eucalyptus grandis, the combined treatment decreased the greatest number of mechanical properties of wood.

PROPRIEDADES FÍSICO-MECÂNICAS DE PAINÉIS AGLOMERADOS COM Bambusa tuldoides E Pinus taeda

This study investigated the physical and mechanical properties of particleboards formed of bamboo (Bambusa tuldoides) and pine (Pinus taeda) and combinations between them. To this end, panels were made, defined by the use of each type of particle (pure or mixed), being set 0, 25, 50, 75 and 100% of proportion to the dry weight, total of 36 panels. The physical tests performed were the moisture content, mass density observed, absorption of water and swelling in thickness and the mechanics were static bending test, screw withdrawal test and internal bond. The results tested for simple correlation and regression analysis. In general, panels pure pine showed better results than just the panels formed by bamboo. The inclusion of bamboo decreases mainly the mechanical properties of panels. All panels were below the minimum standards for the physical and mechanical tests, only internal bond in panels of pine homogeneous had higher values ​​than commercial standards.

Biological resistance of Eucalyptus grandis and Eucalyptus cloeziana woods treated to the decay fungi under laboratory conditions

The present study aimed to evaluate the biological resistance of treated wood from Eucalyptus grandis and Eucalyptus cloeziana under the action of biodeteriorative organisms in laboratory testing. Thus, we used trees of Eucalyptus grandis and Eucalyptus cloeziana, both 16 years old, which was converted into planks and subjected to preservative treatment in an autoclave with chromate copper arsenate (CCA). Then, it was made the specimens for the conduct of accelerated decay test, as recommended by ASTM. From the results, it was observed for the fungus Trametes versicolor that the preservative treatment was effective in reducing the biological degradation of the wood of the two species, with reduced mass loss in 35.17 and 82.31% for wood Eucalyptus grandis and Eucalyptus cloeziana, respectively, as for the fungus Gloeophyllum trabeum mass loss was reduced by 6.79 and 96.65%, compared to the control. Based on the conditions of realization of the present study, it was observed that preservative treatment with CCA is effective in the increasing the biological resistance of the wood under the action of fungi Trametes versicolor and Gloeophyllum trabeum.