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|Título:||Heat induced colour changes of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood|
|Citação:||Esteves, B., Velez Marques, A., Domingos, I., Pereira, H 2008 Heat induced colour changes of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood. Wood Science and Technology. 42(5) 369-384. DOI : 10.1007/s00226-007-0157-2|
|Resumo:||Heat treatment of Pinus pinaster and Eucalyptus globulus wood was made by hot air in an oven during 2 to 24 h at 170-200 ºC and by steam in an autoclave during 2 to 12 h at 190- 210 ºC. The colour parameters L*, a* and b* were determined by the CIELAB method on radial, tangential and transverse sections for untreated and treated wood, and their variation with the treatment (ΔL*, Δa* and Δb*) were calculated in percent. In the untreated woods, for eucalypt wood lightness (L*) varied between 54.1- 63.8% with a* between 7.4-8.5 and b* 15.7-19.9, and for pine wood L* varied between 67.3-76.1%, a* between 6.9 -7.6 and b* 16.3 -24.1. With the heat treatment wood became darker, more for oven treatment (ΔL* about 50% for 4% mass loss), and at the same treatment conditions more for eucalypt wood. In general the contribution of the red colour (a*) and yellow (b*) decreased with the heat treatment. The transverse section darkened less in the two species and for both treatments, with small differences between radial and tangential sections. Lightness decrease was related to chemical changes, with good correlations with glucose (R2= 0.96), hemicelluloses (R2 = 0.92) and lignin (R2 = 0.86). As regards colour, the heat treatments showed an interesting potential to improve the wood quality for solid timber products from pine and eucalypt.|
|Aparece nas colecções:||ESTGV - DEM - Artigos publicados em revista científica|
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