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Teles R.F.,Instituto Federal Of Educacao | da Costa A.F.,University of Brasilia | de Souza M.R.,Laboratorio Of Produtos Florestais Lpf
Floresta e Ambiente | Year: 2016

Although the chemical treatments increase wood durability, there are side effects due to the use of some products, such as the change of its original color and in its surface. The present work aimed to evaluate the surface of three tropical wood species impregnated with CCA preservative using colorimetric and roughness techniques. We used three tropical wood species representing groups of low, medium and high density. The color of the wood samples changed significantly, darkening with reduction of red and yellow pigments and a tending to surface's greening. Regarding roughness, all samples showed an increase in the arithmetic mean roughness (Ra) and the mean maximum height (Rz), increasing surface roughness.

Santana M.A.E.,Laboratorio Of Produtos Florestais Lpf | Rodrigues L.C.,Nucleo Regional de Policia Tecnico Cientifica | Coradin V.T.R.,Laboratorio Of Produtos Florestais Lpf | Okino E.Y.A.,Laboratorio Of Produtos Florestais Lpf | De Souza M.R.,Laboratorio Of Produtos Florestais Lpf
Holzforschung | Year: 2013

Microscopic analysis of 36 Brazilian Amazon wood species revealed the presence of silica in 12 species, mostly in the ray cells and a few times in the axial parenchyma and fibers. The average amount of silica in these species varied from 0.07% to 1.6% as quantified by flame atomic absorption spectroscopy (FAAS). Statistical analysis gave the following classification in terms of silica contents: very low (< 0.07% ), low (between 0.07% and 0.3% : Diplotropis purpurea and Vatairea paraensis ), medium (between 0.3% and 0.4% : Chrysophyllum lucentifolium, Couratari multiflora, Dacryodes sp., Mezilaurus itauba, Trattinnickia burserifolia, and Trattinnickia rhoifolia ), high (between 0.4% and 0.7% : Astronium gracile and Couratari sp.), and very high (above 0.7% : Apuleia leiocarpa and Couratari stellata ). Copyright © by Walter de Gruyter • Berlin • Boston.

Almeida N.A.,Federal University of Lavras | Mendes L.M.,Federal University of Lavras | Okino E.Y.A.,Laboratorio Of Produtos Florestais Lpf | Garlet A.,Laboratorio Of Produtos Florestais Lpf | And 2 more authors.
Cerne | Year: 2012

The objectives of this study were to evaluate the natural resistance of composite and solid wood panels from Toona ciliata to fungal attack through accelerated laboratory testing, to characterize the anatomical components of the wood according to IAWA, to quantify the soluble and insoluble lignin contents by acid hydrolysis and to determine the colorimetric parameters before and after fungal attack by using the CIE-L*a*b*(1976) system. Solid wood was classified as moderately and highly resistant to white-rot fungus (Trametes versicolor) and to brown-rot fungus (Gloeophyllum trabeum). OSB panels were found to be resistant and moderately resistant to white-rot fungus and highly resistant to brown-rot fungus. Variation in species and particle type did not have a positive effect on the treatments. As regards the wood, both fungi were inhibited by the presence of phenolic resin. Particleboard panels were classified as moderately resistant to white-rot fungus. Treatments T2 (cedar) and T4 (cedar-eucalyptus) were resistant while treatment T3 (cedar-pine) was not resistant to attack by brown-rot fungus. The urea- formaldehyde resin failed to inhibit attack in the same way the phenolic resin did. Anatomically, the species was found to have medium texture, straight vessel lines, pleasant smell after incision and poor luster on the radial surface. Its anatomical structure favored colonization by the threadlike filaments of the fungi. All treatments caused wood darkening after attack by the G. trabeum fungus, with total variation in color. It was observed that with weight loss an increase followed in insoluble lignin contents, in all treatments, indicating that this chemical property is a determining factor in wood resistance to the attack of the fungi being evaluated.

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