Resistance to artificial weathering of four tropical woods: the effect of the extractives

As madeiras tropicais: garapeira (Apuleia leiocarpa), tauari (Couratari stellata), itaúba (Mezilaurus itauba) e marupá (Simarouba amara) foram selecionadas para examinar o efeito da presença dos extrativos na variação de cor e no processo de fotodecomposição das suas superfícies. Amostras com e sem extrativos foram submetidas a ciclos de radiação ultravioleta (350 nm) e água até totalizar 2.000 horas de irradiação e 400 horas de lixiviação. A mudança da cor natural das madeiras foi monitorada por espectrocolorimetria de reflexão difusa. Amostras de marupá e tauari com teores de extrativos menores que 2% exibiram variação de cor com o aumento do tempo de tratamento quase iguais às amostras sem extrativos. A resistência anormal do tauari à alteração de cor não pode ser atribuída aos seus extrativos. Para a garapeira e para a itaúba, a presença de 11,7 e 7,42% de extrativos respectivamente acelerou a velocidade de variação de cor. A análise dessas variações de cor indica que os extrativos, nesse caso, agiram acentuando a cor natural da madeira. Adicionalmente, verificou-se que o tauari foi a madeira mais resistente à variação de cor do grupo estudado, seguido pela garapeira, marupá e itaúba todas com extrativos.The tropical woods Apuleia leiocarpa, Couratari stellata, Mezilaurus itauba and Simarouba amara were selected to examine the effect of the presence of the extractives in the color variation and in the photodecomposition process of their surfaces. Samples with and without extractives were submitted to cycles of ultraviolet radiation (350 nm) and immersion in water until totalizing 2,000 hours of irradiation and 400 hours of water leaching. Changings in the natural wood colors were monitored by diffuse reflectance spectroscopy. Samples of Simarouba amara and Couratari stellata with extractives content of 2% or less showed color variation with time of treatment almost similar to the samples without extractives. The abnormal resistance of Couratari stellata to color changing can not be attributed to extractives. For the Apuleia leiocarpa and Mezilaurus itauba woods, the presence of 11,7% and 7,42% of extractives compounds, respectively, accelerated the color variation rate. Analysis of the color variation indicated that the extractives, in this case, acted by intensifying the natural wood color. Additionally, it was verified that Couratari stellata was the more resistant wood to color variation in this studied group of woods, followed by Apuleia leiocarpa, Simarouba amara and Mezilaurus itauba, all with extractives

Resistance to artificial weathering of five tropical woods and of two finish products

Os objetivos do trabalho foram avaliar o processo de fotodecomposição da madeira de cinco espécies tropicais e analisar o efeito de proteção de dois produtos de acabamento de madeiras quando submetidos ao intemperismo artificial. Foram empregadas as madeiras de ipê-roxo (Tabebuia impeginosa), itaúba (Mezilaurus itauba), maçaranduba (Manilkara huberi), tatajuba (Bagassa guianensis) e tauari (Couratari sp.). Amostras destas madeiras foram submetidas a ciclos de radiação ultravioleta (UV) e água até perfazer um total de 2.000 horas de irradiação e 400 horas de lixiviação em água. A mudança da cor natural das madeiras, indicativo do processo de fotodegradação, e o grau de proteção de um verniz poliuretânico transparente e de um “stain” semitransparente foram monitorados por espectrocolorimetria. As espécies mais resistentes foram o ipê-roxo e tauari, seguidas pela maçaranduba, itaúba e tatajuba respectivamente. O verniz forneceu proteção por tempo maior ao ipê-roxo e à maçaranduba, enquanto o “stain” foi mais eficiente para a itaúba e tatajuba. Ambos os produtos tiveram desempenho similar para a madeira de tauari.This work aimed at evaluating the photodecomposition process of five tropical wood species and the protection effect of two wood finishing products under artificial weathering. Woods of Tabebuia impeginosa, Mezilaurus itauba, Manilkara huberi, Bagassa guianensis and Couratari sp. were employed. Samples were submitted to cycles of 2,000 hours of ultraviolet radiation (UV) and 400 hours of water leaching. Changes in the natural color of wood, indicative of the photodegradation process, and the protection degree of a transparent poliuretanic varnish and a semitransparent stain were monitored by spectrocolorimetry. The most resistant wood species were Tabebuia impetiginosa and Couratari sp. followed by Manilkara huberi, Mezilaurus itauba and Bagassa guianensis, respectively. The varnish protected Tabebuia impetiginosa and Manilkara huberi for a long period, while the stain seemed to be more efficient for Mezilaurus itauba and Bagassa guianensis. Both products presented similar performance for Couratari sp

Characterization of wood decay by rot fungi using colorimetry and infrared spectroscopy

Amostras de madeiras de marupá (Simarouba amara) e andiroba (Carapa guianenis) foram submetidas ao ataque dos fungos Trametes versicolor (podridão branca) e Gloeophylum trabeum (podridão parda). A colorimetria foi empregada para determinar as cores das madeiras antes e após o ataque dos fungos. Para acompanhar a variação do teor dos compostos químicos foi utilizada a técnica de espectroscopia de refletância difusa no infravermelho médio. Ambas as espécies foram consideradas não resistentes ao fungo de podridão branca. Para o fungo de podridão parda, a andiroba foi considerada resistente e o marupá não resistente. Ambas as espécies de madeira se apresentaram mais escuras após o ataque do fungo Gloeophyllum trabeum. Já o ataque do fungo Trametes versicolor causou clareamento na madeira da andiroba e escureceu ligeiramente o marupá. Os resultados da análise dos espectros de infravermelho mostraram que em ambas as espécies de madeira houve redução na intensidade das bandas de celulose, hemiceluloses e lignina após o ataque do Trametes versicolor, e redução somente na intensidade da banda de celulose após o ataque do Gloeophyllum trabeum.Wood samples of marupá (Simarouba amara) and andiroba (Carapa guianenis) were submitted to Trametes versicolor (white rot) and Gloeophylum trabeum (brown rot) fungi attack. Colorimetry was used to determine the color of the wood before and after wood decaying fungi. To evaluate the changes in chemical compounds levels in the wood samples, the diffuse reflectance medium infrared spectroscopy was used. Both wood were non resistant against white rot fungus, while with brown rot attack andiroba was resistant and marupá was not. After Gloeophyllum trabeum attack both woods changed to a darken color, and after Trametes versicolor attack andiroba changed to a lighter color and marupá darkened slightly, The analysis showed a reduction in the peak intensity of cellulose, hemicellulose and lignin, for both species, after Trametes versicolor attack and a reduction in the peak intensity of cellulose after Gloeophyllum trabeum attack

Monitoring of biodeterioration of three Amazonian wood species by the colorimetry technique

Objetivou-se avaliar o emprego da colorimetria na caracterização da biodeterioração das madeiras de marupá, jequitibá e cumaru submetidas ao ataque de fungos de podridão branca e parda. Para tanto, corpos de prova de cada espécie amazônica foram submetidos a ensaios de apodrecimento acelerado, de acordo com a American Society for Testing and Materials - ASTM D2017, durante 20 semanas. Os parâmetros colorimétricos L* (luminosidade), a* (coordenada verde-vermelho), b* (coordenada amarelo-azul) e a variação total da cor (∆E) foram determinados semanalmente até a quarta semana, e posteriormente a cada duas semanas até a vigésima semana, com auxílio de um espectrofotocolorímetro. Adicionalmente, foram determinadas as perdas de massa dos corpos de prova. Os resultados permitiram destacar que a colorimetria foi eficaz no monitoramento da biodeterioração da madeira, bem como para diferenciação da podridão branca e parda. As melhores predições da resistência natural aos fungos de podridão branca e parda foram obtidas com os parâmetros b* e L*, respectivamente. Enfatiza-se também, o emprego da ∆E como parâmetro auxiliar na estimativa da biodeterioração da madeira, em razão de suas correlações significativas com a perda de massa.This work aimed to evaluate the use of colorimetry in the characterization of biodeterioration marupá, jequitibá and cumaru wood, submitted to white and brown rot. For this purpose, specimens of each Amazonian species were submitted to accelerated decay tests, according to American Society for Testing and Materials - ASTM D2017, during 20 weeks. With a colorimeter, the colorimetric parameters L* (lightness), a* (green-red coordinate), b* (blue-yellow coordinate) and total color change (ΔE) were determined weekly until the fourth week, and then every two weeks until the twentieth week. Additionally, it was determined the mass loss. The results indicated that the colorimetry was effective in monitoring of biodeterioration of wood, as well as to differentiate white and brown rot. The best predictions of natural resistance to white and brown rot were obtained with the parameters b* and L*, respectively. We also emphasizes the use of ΔE to estimate the biodeterioration of wood, because of their significant correlations with weight loss

Characterization of wood decay by rot fungi using colorimetry and infrared spectroscopy

Amostras de madeiras de marup\ue1 ( Simarouba amara ) e andiroba ( Carapa guianenis ) foram submetidas ao ataque dos fungos Trametes versicolor (podrid\ue3o branca) e Gloeophylum trabeum (podrid\ue3o parda). A colorimetria foi empregada para determinar as cores das madeiras antes e ap\uf3s o ataque dos fungos. Para acompanhar a varia\ue7\ue3o do teor dos compostos qu\uedmicos foi utilizada a t\ue9cnica de espectroscopia de reflet\ue2ncia difusa no infravermelho m\ue9dio. Ambas as esp\ue9cies foram consideradas n\ue3o resistentes ao fungo de podrid\ue3o branca. Para o fungo de podrid\ue3o parda, a andiroba foi considerada resistente e o marup\ue1 n\ue3o resistente. Ambas as esp\ue9cies de madeira se apresentaram mais escuras ap\uf3s o ataque do fungo Gloeophyllum trabeum. J\ue1 o ataque do fungo Trametes versicolor causou clareamento na madeira da andiroba e escureceu ligeiramente o marup\ue1. Os resultados da an\ue1lise dos espectros de infravermelho mostraram que em ambas as esp\ue9cies de madeira houve redu\ue7\ue3o na intensidade das bandas de celulose, hemiceluloses e lignina ap\uf3s o ataque do Trametes versicolor, e redu\ue7\ue3o somente na intensidade da banda de celulose ap\uf3s o ataque do Gloeophyllum trabeum.Wood samples of marup\ue1 ( Simarouba amara ) and andiroba ( Carapa guianenis ) were submitted to Trametes versicolor (white rot) and Gloeophylum trabeum (brown rot) fungi attack. Colorimetry was used to determine the color of the wood before and after wood decaying fungi. To evaluate the changes in chemical compounds levels in the wood samples, the diffuse reflectance medium infrared spectroscopy was used. Both wood were non resistant against white rot fungus, while with brown rot attack andiroba was resistant and marup\ue1 was not. After Gloeophyllum trabeum attack both woods changed to a darken color, and after Trametes versicolor attack andiroba changed to a lighter color and marup\ue1 darkened slightly, The analysis showed a reduction in the peak intensity of cellulose, hemicellulose and lignin, for both species, after Trametes versicolor attack and a reduction in the peak intensity of cellulose after Gloeophyllum trabeum attack

Evaluation of a NIR handheld device and PLS-DA for discrimination of six similar amazonian wood species

Supervising wood exploitation can be very challenging due to the existence of many similar species and the reduced number of wood identification experts to meet the demand. There is evidence that valuable endangered wood species are being smuggled disguised as other species. Near infrared spectroscopy (NIRS) and chemometrics has been successfully used to discriminate between Amazonian wood species using high resolution instruments. In this study, a handheld spectrometer was evaluated for the discrimination of six visually similar tropical wood species using PLS-DA. Woods of mahogany (Swietenia macrophylla) and cedar (Cedrela odorata), both high value tropical timber species included in Appendixes II and III of the CITES, respectively; crabwood (Carapa guianensis); cedrinho (Erisma uncinatum); curupixá (Micropholis melinoniana); and jatobá (Hymenea coubaril). The data for model development and validation take into account both laboratory and field measurements. Outlier exclusion was performed based on Hotelling T2, residuals Q and errors in the estimated class values. The efficiency rates were higher than 90% for all species, showing that the handheld NIR combined with PLS-DA succeeded in discriminate between these species. These results stimulate the application of handheld NIR spectrometers in the supervision of wood exploitation, which can contribute to the species preservation

Ensaio acelerado de laboratório de três espécies de madeiras da Amazônia chamadas de Tauari, expostas aos fungos de podridão-branca e parda e resposta colorimétrica de acordo com o sistema CIE L* a* b*

Os objetivos deste estudo foram: avaliar a durabilidade natural de três espécies de tauari (Couratari guianensis Aublet, Couratari oblongifolia Ducke & Knuth R. e Couratari stellata A.C.Smith), relatar os parâmetros colorimétricos de acordo com o sistema CIE L * a * b * 1976 assim como mostrar a aparência dos blocos de madeira antes e após o ataque. Dois fungos de podridão-parda [Gloeophyllum trabeum (Persoon ex Fries) Murril. e Lentinus lepideus Fr.] e dois de podridão-branca [Trametes versicolor (Linnaeus ex Fries) Pilat e Ganoderma applanatum (Pers. ex Wallr.)] foram utilizados. A madeira de tauari foi classificada como "moderadamente resistente" a "resistente" quando exposta aos fungos Gloeophyllum trabeum, Trametes versicolor e Ganoderma applanatum. O conteúdo de extrativos das amostras atacadas diminuiu quando comparado com o controle, exceto Couratari stellata expostos a Ganoderma applanatum. Por outro lado, os conteúdos de cinzas aumentaram quando comparados com o controle, exceto para a madeira de Couratari stellata exposto ao Gloeophyllum trabeum. Todos os blocos de madeira atacados e as serragens tornaram-se mais escuras, exceto para a serragem de Couratari stellata exposto ao fungoTrametes versicolor, e mais vermelho do que a amostra sem ataque. O ΔE * médio do bloco de madeira e serragem, atacados, atingiram 29,5 e 14,3, respectivamente.The purposes of this study were to: evaluate de natural durability of three species of tauari (Couratari guianensis Aublet, Couratari oblongifolia Ducke & R.Knuth and Couratari stellata A.C.Smith), report the colorimetric parameters according to CIE L*a*b* 1976 system and also show the appearance of control and attacked wood blocks. Two brown-rot [Gloeophyllum trabeum (Persoon ex Fries) Murril. and Lentinus lepideus Fr.] and two white-rot [Trametes versicolor (Linnaeus ex Fries) Pilat and Ganoderma applanatum (Pers. ex Wallr.)] fungi were used.Tauari wood was classed as "moderately resistant" to "resistant" when exposed toGloeophyllum trabeum, Trametes versicolor andGanoderma applanatum fungi. All extractives' contents of attacked samples decreased when compared with the control (sound wood), exceptCouratari stellata exposed to Ganoderma applanatum.Conversely, all ash contents increased when compared with the control, except Couratari stellata exposed to Gloeophyllum trabeum. All attacked wood blocks and wood meal samples were darker, except wood meal from Couratari stellata exposed toTrametes versicolor, and redder than the control. The∆E* mean value in attacked wood blocks and wood meal samples attained 29.5 and 14.3, respectively

Exploratory analysis of the distribution of lignin and cellulose in woods by raman imaging and chemometrics

The determinations of cellulose and lignin are important in wood analysis from both perspectives: chemistry composition, commercial and industrial application of woods. In this context, Raman image spectroscopy was applied in the determination of cellulose and lignin distribution in wood surfaces of Swietenia macrophylla King (Mahogany) and Eucalyptus hybrid (E. urophylla × E. camaldulensis). The relative concentration maps were obtained by applying a multivariate curve resolution procedure. The estimated Raman spectra for cellulose and lignin agrees with the ones available in the literature. The cellulose concentration maps showed similar variations for both studied species with an average value of nearly 85% as obtained by the reference method. The lignin concentration maps were somewhat different. The Eucalyptus hybrid presents a broader distribution (20 to 45%) while for Mahogany it is nearly constant, around 25%, with localized regions presenting contents of 45 to 65% of lignin. The reference method showed that the mean lignin content of both species is 27%. The cellulose and lignin concentration maps agree with the biological functions of the anatomic structures observed in the images