Karina Soares Modes

Método ultrassônico para estimativa do módulo de elasticidade de madeiras de Pinus taeda tratadas termicamente

This study aimed to estimate the modulus of elasticity of Pinus taeda thermally modified wood by ultrasonic nondestructive method. To achieve this, 93 samples with dimensions 2.5x2.5x41.0cm (thickness, width and length) from pine boards were prepared. The wood samples were thermally modified through two distinct treatments (Combination and Oven). The Combination treatment was performed in an autoclave at 130oC±3°C and pressure of 2kgf cm-2 for 3 hours. After a period of conditioning, the wood samples were heated in an electric oven 160°C±1°C for the same time. On the other hand, wood samples of the Oven treatment was modified with only last condition. The mathematical models showed r2 between 0.48 and 0.66 and significance at 1% of probability of error. Thus, improvement of ultrasonic nondestructive tests shows that technique could be useful and efficient in order to estimate modulus of elasticity of Pinus taeda wood.

Resistência natural das madeiras de sete espécies florestais ao fungo Pycnoporus sanguineus causador da podridão-branca

Conduziu-se esta pesquisa, com o objetivo de avaliar a resistencia natural das madeiras de platano (Platanus x acerifolia), acoita-cavalo (Luehea divaricata), nogueira-pecan (Carya illinoensis), canafistula (Peltophorum dubium), araucaria (Araucaria angustifolia), eucalipto (Eucalyptus grandis) e uva-do-japao (Hovenia dulcis), submetidas ao ensaio de apodrecimento acelerado com o fungo causador da podridao-branca Pycnoporus sanguineus. Determinou-se a massa especifica aparente a 12%. O ensaio de apodrecimento foi conduzido em frascos de vidro (capacidade de 500 mL) preenchidos com 100 g de solo umedecido, autoclavados e mantidos a 25oC. O estabelecimento inicial da colonia fungica ocorreu em placas suporte de madeira de alburno de Pinus elliottii. Foram utilizadas tres amostras de cerne de dimensoes 9,0 x 25,0 x 25,0 mm para cada especie avaliada e, apos 16 semanas de incubacao, calcularam-se as porcentagens de perda de massa sofridas. O grau de resistencia natural foi efetuado em funcao das porcentagens de perda de massa. As medias obtidas de perda de massa foram comparadas pelo teste de Tukey a 5% de significância. A resistencia natural do cerne nao foi influenciada pela massa especifica aparente. A madeira de Carya illinoensis, Eucalyptus grandis, Platanus x acerifolia, Luehea divaricata e Peltophorum dubium foram classificadas como muito resistentes, Houvenia dulcis, como resistente e Araucaria angustifolia, como de resistencia moderada.

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.

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.