Use of glass transition temperature for stabilization of board's cracks of Eucalyptus grandis

Calonego, Fred Willians; Severo, Elias Taylor Durgante; Cunha, Antônio Ribeiro da; Gaia, Daiane C

doi:10.1590/s0001-37652010000300025

Cited by 11 publications

(8 citation statements)

References 9 publications

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“…Two grooves were machined to a depth equal to one-third of the radius of each log at 10 cm from the crosscut section in all logs, as recommend in the literature. [9,10,20,29]…”

Section: Collection Of Materialsmentioning

confidence: 99%

“…Several authors [1,3,[8][9][10][11][12][13][14][15]17,18,20] have shown that steaming is a technique that may solve several problems of various kinds of wood. However, in conditions applied by this study, the log steaming, steaming prior to drying, and steamed logs plus presteamed lumber cannot be applied for H. brasiliensis wood without adversely affecting the decay resistance of wood.…”

Section: Effect Of Steaming On Decay Resistance Of Rubberwood To Whitmentioning

confidence: 99%

“…The main problems regarding the use of Hevea brasiliensis (rubberwood), particularly as lumber, are due primarily to their intrinsic characteristics, such as drying defects such as warp, twist, bow, and splitting during the drying process [1][2][3][4] ; fast biodegradation and susceptibility to fungi and insects after felling [2,5] ; and high levels of growth stress. [4,6,7] Steaming wood is a technique that may alleviate the problems during the sawing and drying processes, and it is applied for a variety of other purposes, such as to reduce growth stress levels, [8][9][10] change color, improve the dimensional stability, [11][12][13][14] increase the permeability [15] and drying rate, and reduce the initial moisture content (IMC), moisture gradient, and drying defects. [1,3,13,14,[16][17][18][19] When steamed at 54°C, the H. brasiliensis logs produce boards with higher end-cracks, where 704 and 239 mm are in their respective central and peripheral boards, whereas the steamed logs at 92°C present a greater relief of growth stresses, as observed by the smaller difference between the cracks' length in the central (394 mm) and peripheral (165 mm) boards.…”

Section: Introductionmentioning

confidence: 99%

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Drying behavior and decay resistance of rubberwood from steamed log and presteamed lumber

et al. 2018

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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.

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“…Two grooves were machined to a depth equal to one-third of the radius of each log at 10 cm from the crosscut section in all logs, as recommend in the literature. [9,10,20,29]…”

Section: Collection Of Materialsmentioning

confidence: 99%

Section: Effect Of Steaming On Decay Resistance Of Rubberwood To Whitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Drying behavior and decay resistance of rubberwood from steamed log and presteamed lumber

et al. 2018

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“…The decrease of the moisture content of wood increases the glass transition temperature (Kutnar and Sernek 2007). The glass transition temperature can also change according to the wood species (Calonega et al 2010).…”

Section: Densification Of Woodmentioning

confidence: 99%

The Effect of Densification Temperature on Some Physical and Mechanical Properties of Scots Pine (Pinus Sylvestris L.)

Ülker¹,

Imirzi²,

Burdurlu³

2012

BioResources

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As wood's density increases, strength properties tend to increase due to a decrease in cavity volume. This study aimed to determine the effect of temperature levels in the densification process with an open-system thermomechanical method on the density, bending, modulus of elasticity in bending, compression, shear strength, and Brinell hardness in radial/tangential directions of Scots pine. The densification process significantly increased the strength properties of Scots pine. This increase stemmed from the decrease in the rate of cavities with the densification process, which also resulted in an increase in cell wall elements that have load-bearing properties per unit volume. An increase in densification temperature decreased strength properties. The decrease in the strength values can be explained by increasing chemical degradation with a rise in the temperature level. The most suitable temperature level was 120 º C for a higher bending, shear, and compression strength, and it was 140 º C for a higher radial and tangential hardness in the densification of Scots pine. Increases of 42% in the bending strength, 20% in the shear strength, 47% in the compression strength, 242% in the radial hardness, and 268% in the tangential hardness were obtained after densification.

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“…For sugarcane bagasse particleboard treated with temperatures at 200oC, 230oC and 260oC for a period of eight and twelve minutes, , observed strength reduction from 230oC and twelve minutes of heat treatment. Calonego et al (2010) studied the heat treatment effect in Eucalyptus grandis wood properties and verified that the static bending of the wood was not significantly altered by the heat treatment. According to the author, the rearrangement of chemical constituents after heat treatment of wood and/or the cellulose crystalline area increase, and the consecutive approximation of the micelles showed by Wikberg and Maunu (2004) are mostly the most considerable explanation.…”

Section: Resultsmentioning

confidence: 88%

Propriedades De Painéis Aglomerados Submetidos Ao Tratamento Térmico

Melo¹,

Muhl

Stangerlin³

et al. 2018

Ciênc. Florest.

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The particleboards are the most consumed in the world, where much of the demand is associated to furniture sector. This study aims to assess the heat treatment effect on particleboard panels. The experiment consisted of four treatments and the control sample, evaluating temperatures of 160°C and 180°C for six and twelve minutes. Commercial particleboard panels were produced with particles of Eucalyptus sp. and urea-formaldehyde synthetic resin. Samples for physical testing (water absorption, and thickness swelling) and mechanical (static bending strength and screw withdrawal strength) were taken from these panels. For physical properties, the assessed heat treatments influenced significantly the water absorption of the panels after 24 hours of immersion. The treatment that utilized temperature of 180°C for six minutes provided the best performance. Concerning to the mechanical properties, the evaluated treatments had non-significantly influence in the panels strength. Keywords: wood panels; thermal rectification; wood technology. RESUMOOs painéis aglomerados são os mais consumidos no mundo, sendo que grande parte da demanda destes painéis está associada ao setor moveleiro. O presente estudo teve como objetivo avaliar o efeito do tratamento térmico em painéis aglomerados. O experimento consistiu de quatro tratamentos mais a testemunha, avaliando as temperaturas de 160 e 180°C por períodos de seis e doze minutos. Foram utilizados painéis aglomerados comerciais produzidos com partículas de Eucalyptus sp. e, resina sintética ureia-formaldeído. Destes painéis foram retiradas amostras para os ensaios físicos (absorção de água e inchamento em espessura) e mecânicos (resistência à flexão estática e resistência ao arrancamento de parafuso). Para as propriedades físicas, os tratamentos térmicos avaliados influenciaram significativamente a absorção de água dos painéis após 24 horas de imersão. O tratamento que utilizou a temperatura de 180°C por seis minutos foi o que proporcionou o melhor desempenho. Já para as propriedades mecânicas, os tratamentos avaliados não influenciaram significativamente a resistência dos painéis. Palavras-chave: painéis de madeira; termorretificação; tecnologia da madeira. INTRODUTIONThe wood and its derivatives products can take on and give off water to balance out with the environment due a porous structure and capillarity phenomenon. As a result, there are dimensional and 1 Engenheiro Florestal, Dr., Professor do

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Use of glass transition temperature for stabilization of board's cracks of Eucalyptus grandis

Cited by 11 publications

References 9 publications

Drying behavior and decay resistance of rubberwood from steamed log and presteamed lumber

Drying behavior and decay resistance of rubberwood from steamed log and presteamed lumber

The Effect of Densification Temperature on Some Physical and Mechanical Properties of Scots Pine (Pinus Sylvestris L.)

Propriedades De Painéis Aglomerados Submetidos Ao Tratamento Térmico

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