Química e colorimetria da madeira de Eucalyptus grandis W. Mill ex Maiden termorretificada

Zanuncio, Antônio José Vinha; Nobre, João Rodrigo Coimbra; Motta, Javan Pereira; Trugilho, Paulo Fernando

doi:10.1590/s0100-67622014000400020

Cited by 15 publications

(25 citation statements)

References 30 publications

(30 reference statements)

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“…Color changes take place due to modifications in the chemical structure of wood, related to thermal degradation of hemicellulose and lignin, as well as condensation and migration of extractives to the wood surface. This phenomenon has been also observed for wood submitted to hydrothermal treatment (SUNDQVIST; MORÉN, 2002;MORI et al, 2004;VARGA;ZEE, 2008;ZANUNCIO et al, 2014).…”

Section: Several Commercial Processes Have Been Introduced Insupporting

confidence: 61%

Color change and thermogravimetric analysis of thermally treated Eucalyptus grandis wood

Silva¹,

Cremonez²,

Nisgoski³

2019

RCM

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Eucalyptus grandis wood was thermally treated at two different temperatures (150 °C and 200 °C) in a muffle furnace with steam. The surface color change was measured right after the treatment and in wood samples stored for two years inside a carton box without light exposure. Samples were analyzed by thermogravimetry to detect variation of thermal degradation behavior for different treatment temperatures. Thermally treated wood was darker when compared to control samples. The storage time influenced the wood surface color, with the surface becoming darker and redder. Thermogravimetric analysis revealed a peak of wood degradation between 300 °C and 400 °C for thermally treated samples.

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Section: Several Commercial Processes Have Been Introduced Insupporting

confidence: 61%

Color change and thermogravimetric analysis of thermally treated Eucalyptus grandis wood

Silva¹,

Cremonez²,

Nisgoski³

2019

RCM

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“…This process involves application of heat of 160-230°C on the wood to be treated (Kocaefe et al 2008, Esteves and Pereira 2009, Pétrissans et al 2014. This temperature range degrades the hemicellulose and extractives (Brito et al 2008, Zanuncio et al 2014c. As positive effect, heat treatment reduces hygroscopicity and increases the dimensional stability (Esteves et al 2013, Palermo et al 2014, Ratnasingam and Ioras 2012, Bal and Bektaş 2012, as negative effect, it damages the mechanical properties of wood (Garcia et al 2012, Dundar et al 2012, Cademartori et al 2012, Dubey et al 2012.…”

Section: Introductionmentioning

confidence: 99%

Effect of extractives on wood color of heat treated Pinus radiata and Eucalyptus pellita

Zanuncio

Carvalho

Souza

et al. 2015

Maderas, Cienc. tecnol.

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Heat treatment can change wood color without any use of environmentally harmful chemicals, and the efficiency of this process depends on the raw material to be treated. The objective of this study was to evaluate the influence of extractives on the color change of Eucalyptus pellita and Pinus radiata wood during heat treatment. The extractives were extracted in cold water and in dichloromethane as well as totally removed and the wood was treated at 170°C and 200°C for three hours under atmospheric pressure and in presence of air for evaluating the lightness (L*), green-red coordinate (a*), blue-yellow coordinate (b*), color saturation (C) and tonality angle (H) values. Pinus radiata wood was more resistant to discoloration by heat treatment. The removal of total and cold water-soluble extractives before heat treatment changed the L* value of Pinus radiata, a* value of Eucalyptus pellita, and b*, C, and H values of both species. Removal of extractives soluble in dichloromethane did not affect the color of heat treated wood. Thus, understanding the influence of extractives on heat treated wood can allow adapting the raw material to the process for enhancing the applicability of heat treatment for changing wood color.

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“…Once submitted to hydrothermal processing, hemicellulose depolymerisation occurs, forming soluble compounds such as oligosaccharides, monosaccharides, sugardecomposition products and acetic acid (Gullón et al 2010). Zanuncio et al (2014) also reported the increase of extractive content in heat-treated Eucalyptus grandis wood at 200 and 230 °C. Reduction in the sugars composing the hemicellulose structure (Table 2) can be explained by the fact that hemicelluloses are less tolerant to heat because their ramifications are easily removed from the main chain, degrading into volatile compounds (Wang et.…”

Section: Discussionmentioning

confidence: 89%

Hydrothermal Treatment of Eucalyptus Strand Particles for Improvement of Oriented Strand Board (Osb) Panels

Carvalho¹,

Ajv²,

Carneiro³

et al. 2020

JTFS

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The aim of this study was to evaluate the effect of hydrothermal treatment on the chemical composition of Eucalyptus strand particles and on the physical and mechanical properties of oriented strand board (OSB) panels. Strand particles of Eucalyptus were pre-hydrolysed at 130, 150 and 170 °C for 7 and 21 minutes. The extractives, lignin, carbohydrates, pH, equilibrium moisture content, mass loss and contact angle were evaluated. The OSB panels were fabricated using a phenol-formaldehyde adhesive (8%), 0.7 g cm-3 nominal density and a pressing cycle with 170 °C, 3.14 MPa for 8 minutes. These panels were kept in a climate chamber at 20 ± 2 °C and 65 ± 3% relative humidity to determine their physical and mechanical properties. The hydrothermal treatment, mainly at 170 °C, degraded the hemicelluloses, especially galactans, xylans and arabians. The treatments at this temperature showed the best results for improving the dimensional stability, as well as reducing the moisture equilibrium content, water absorption and thickness swelling after 24 hours of immersion, without losing mechanical resistance. Therefore, hydrothermal treatment can be an important alternative for improving OSB panel quality.

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Química e colorimetria da madeira de Eucalyptus grandis W. Mill ex Maiden termorretificada

Cited by 15 publications

References 30 publications

Color change and thermogravimetric analysis of thermally treated Eucalyptus grandis wood

Color change and thermogravimetric analysis of thermally treated Eucalyptus grandis wood

Effect of extractives on wood color of heat treated Pinus radiata and Eucalyptus pellita

Hydrothermal Treatment of Eucalyptus Strand Particles for Improvement of Oriented Strand Board (Osb) Panels

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