Effect of Pyrolytic Temperatures on the Longitudinal Strength of Dry Douglas-Fir

Etris, SF; Lieb, KC; Sisca, VK; Moore, IC; Batik, AL; Schaffer, EL

doi:10.1520/jte10025j

Cited by 76 publications

(8 citation statements)

References 11 publications

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“…However, the same authors verified that the chemical treatment provoked an increase of the wood permeability, behavior that Schaffer [27] claims to affect the dimensional stability of composites, especially when used in more severe environmental humidity conditions. Therefore, although the thermo-mechanical treatment presented lower results than chemical treatment, the application of this treatment reduces higroscopicity of wood [26], which results in greater dimensional stability [4] and use possibilities. Fig.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the Effect of Thermo-mechanical Treatment on the Resistance of Commercial OSB to Decay Fungi

Crisóstomo

Menezzi

2019

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The chemical treatment of wood has been widely used in combating rot fungi. However, it's a process that involves the insertion of chemical agents, which are subject to leaching when exposed to weathering. In this context, the thermomechanical modification seeks to increase the durability of wood, without polluting the environment. Samples of untreated and thermo-mechanically treated Oriented Strand Board (OSB) were exposed to the attack of rotting fungi. Both untreated and treated samples were classified as resistant to the attack of T. versicolor (white-rot). To the attack of G.trabeum (brown-rot), the untreated samples were classified as moderate resistance, and the treated samples as resistant. The results of mass loss showed that the thermo-mechanical treatment caused an increase of 19.34 % (whiterot) and 43.03 % (brown-rot) in the OSB resistance, and also improved the OSB resistance class from moderately resistant to resistant to brown-rot fungi.

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Section: Resultsmentioning

confidence: 99%

Evaluation of the Effect of Thermo-mechanical Treatment on the Resistance of Commercial OSB to Decay Fungi

Crisóstomo

Menezzi

2019

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“…After 456 hours of exposure at a temperature of 60 °C, all wood species showed a significant decrease in the mean value of shear strength (Table 3) due to the degradation of the constituent compounds of wood, which begin to show the degradation effects from 55 °C (Kollmann & Côté, 1968;Schaffer, 1973). According to Castro et al 2015, Jatobá presents 31.88% of lignin, 12.78% of extractives, 0.36% of minerals, and 54.98% of holocellulose (cellulose plus hemicellulose).…”

Section: Resultsmentioning

confidence: 99%

Influence of Exposure Time to Operating Temperature on Shear Strength of Wood Used in Roof Structures

Christofóro

Almeida

et al. 2019

Eng. Agríc.

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Wood is one of the main materials used in the constructing of covering structures (roofs) because of its versatility. Under this situation, due to solar radiation incidence, the temperature can exceed 60 °C and, such as other environmental conditions, influence the mechanical properties of the wood in use. The aim of this research was to study the influence of exposure time of the wood of four different hardwood species at a temperature of 60 °C on the shear strength parallel to fibers. The wood of the following species was used: Cupiúba (Goupia glabra), Eucalyptus (Eucalyptus saligna), Garapeira (Apuleia leiocarpa), and Jatobá Tamarindo (Hymenaea sp.). In order to investigate the effect of exposure time (0, 168, 456, 720, and 2160 hours) of the wood species in an oven (60 °C) on the values of shear strength in the direction parallel to fibers, an analysis of variance (ANOVA) was carried out at 5% significance level. According to the results, the time the wood was exposed to the operating temperature significantly influenced the shear strength in the direction parallel to fibers. In addition, all species showed a decrease in shear strength after 456 hours of exposure at a constant temperature of 60 °C.

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“…Vários trabalhos foram realizados para determinar a influência da temperatura sobre as propriedades mecânicas da madeira submetida a altas temperaturas (Schaffer, 1967(Schaffer, , 1973Pinto, 2005;Figueroa & Moraes, 2009), mas todos analisaram somente a influência da temperatura sobre as propriedades mecânicas da madeira, diferentemente deste trabalho, que analisou a influência do gradiente de temperatura e do tempo de exposição ao calor sobre a perda de seção resistente da madeira submetida a diferentes métodos de retardar a propagação da combustão no interior da madeira. Os resultados médios dos ensaios de compressão paralela às fibras constam nas Tabelas 4, 5 e 6.…”

Section: Ensaio Mecânicounclassified

“…Os resultados obtidos para a resistência à compressão para a temperatura de 200 °C foram superiores aos obtidos por Schaffer (1973), Knudson & Schniewind (1975), que analisaram a influência da temperatura nas propriedades mecânicas para a espécie Pseudotsuga menziesii, e por Barreira (2008), para a espécie Schizolobium amazonicum. Para a madeira de C. citriodora submetida ao aquecimento de 300 °C, sob os diferentes tempos de Tabela 3.…”

Section: Ensaio Mecânicounclassified

“…Análise Termomecânica da Madeira... Schaffer (1973) e Knudson & Schniewind (1975), analisando a espécie Pseudotsuga menziesii, também obtiveram valores de resistência à compressão paralela às fibras inferiores aos valores obtidos neste trabalho. Pinto (2005), adotando a metodologia de Schaffer (1967), que sugere a temperatura de 288 °C como sendo a temperatura característica da base carbonizada, obteve valores de resistência de compressão paralela às fibras para as espécies de Corymbia citriodora e Eucalyptus grandis inferiores aos obtidos neste trabalho.…”

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Análise termomecânica da madeira de Corymbia citriodora submetida a gradientes térmicos

et al. 2014

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RESUMOA madeira, quando exposta a condições de estresse, como no caso de um gradiente de temperatura, pode levar a estrutura de uma determinada instalação ao desmoronamento. A taxa na qual a madeira se converte em carvão é determinante, em função da redução da seção resistente. A presente investigação teve como objetivo avaliar o comportamento termomecânico da madeira de Corymbia citriodora submetida a gradientes de temperatura e diferentes tempos de exposição, com diferentes tratamentos (Verniz e CCB), com o intuito de minimizar o processo de carbonização. No que diz respeito aos ensaios mecânicos, pode-se afirmar que o aumento da temperatura de carbonização e do tempo de exposição das amostras ocasionou um decréscimo da resistência à compressão paralelamente às fibras do material, ocasionado fragilidade de carregamento. Os tratamentos testados (CCB e Verniz) não apresentaram resultados satisfatórios no que diz respeito ao retardo da combustão, não sendo, portanto, recomendáveis para esses fins.Palavras-chave: resistência dos materiais, estruturas de madeira, temperatura. Thermo-mechanical Analysis of Corymbia citriodora Wood Subjected toThermal Gradients ABSTRACT Wood exposed to stress conditions, such as temperature gradients, may lead to collapse of installation structure. The rate at which wood becomes charcoal is crucial because of the reduction of the resistant section. This research aimed to evaluate the thermo-mechanical behavior of Corymbia citriodora wood subjected to temperature gradients and different exposure times, under different treatments (Varnish and CCB), in order to minimize the carbonization process. With respect to mechanical tests, it is possible to affirm that the increase in carbonization temperature and time of exposure of the samples resulted in a decrease in the compression strength parallel to the fibers of the material, causing brittleness. The treatments (Varnish and CCB) tested did not present satisfactory results with respect to combustion delay; therefore, they are not recommended for such purposes.

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Effect of Pyrolytic Temperatures on the Longitudinal Strength of Dry Douglas-Fir

Cited by 76 publications

References 11 publications

Evaluation of the Effect of Thermo-mechanical Treatment on the Resistance of Commercial OSB to Decay Fungi

Evaluation of the Effect of Thermo-mechanical Treatment on the Resistance of Commercial OSB to Decay Fungi

Influence of Exposure Time to Operating Temperature on Shear Strength of Wood Used in Roof Structures

Análise termomecânica da madeira de Corymbia citriodora submetida a gradientes térmicos

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