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http://dx.doi.org/10.5902/1980509819609Os 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 fungo Trametes 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.

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 (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).

The resistance to decomposition of mahogany wood (Sweitenia macrophylla King) ranges from high to moderate level. Wood extractives, mainly due to the presence of phenol compounds are related to the natural durability of wood. The technique of near infrared spectroscopy (NIRS) coupled with multivariate analysis has been applied to assess the extractives and phenols of 41 samples of mahogany in powder form. The hot water-soluble extractives were quantitatively determined, and total phenol content was measured with the Folin-Denis colourimetric reagent. Models were developed with the NIRS data for each of the two variables. The results indicated that NIRS can be a useful tool to a rapid evaluation of the extractive contents and total phenolic compounds of mahogany wood. The method was able to predict the interesting properties with errors lower than 10% (w/w) and had the capability of detecting samples that have a minimum concentration of 2.4% (w/w) of extractives and total phenolic compounds, respectively.

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.

The objectives of the present work were to evaluate the chemical compatibility between coir (Cocos nuciferaL.) and cement and to study treatment methods to improve this compatibility. In the inhibition test, cement hydration temperature evolution was measured in the absence and presence of untreated and treated coir fibres (cold water, hot water and NaOH), besides the addition of 4% of CaCl2. The chemical characterization of untreated and treated coir fibres was done by determining the content of extractives, lignin, and holocellulose. The inhibition test graded the untreated fibre as “extreme inhibition,” ratifying the need to provide it a treatment. Treatments done on coir fibres affected positively the compatibility between cement and fibre, reducing the inhibition. The treatments reduced the lignin coir fibres’ and extractives proportion, whose variation was significantly correlated with the reduction of the inhibitory index. These results indicate a possibility for future incorporation of these fibres into the production of mineral composites.

Brazilian sawdust samples (Caryocar spp.; Manilkara spp.; and Tabebuia spp.) have been used for Pb(II) ions adsorption from water at 25 °C. The series of adsorption isotherms were adjusted to a modified Langmuir equation from data obtained by suspending the sawdust with Pb(NO3)2 solutions, which gave the maximum number of moles adsorbed as 89.10 ± 8.28; 145.04 ± 12.43 and 95.31 ± 8.28 mg g−1 for Caryocar spp.; Manilkara spp.; and Tabebuia spp., respectively. Thermodynamic data of interactions were studied by the calorimetric titration of Pb(II) in aqueous solution. Gibbs free energies were negative for all systems and the adsorption interactions presented the following exothermic enthalpic values: −1.99 ± 0.11; −3.20 ± 0.21 and −2.27 ± 0.11 kJ mol−1 for Caryocar spp.; Manilkara spp.; and Tabebuia spp., respectively. All liquid/solid interface adsorptions were entalpically and entropically driven. These sawdust samples were applied to remove Pb(II) from wastewater of a battery industry of Brasilia, DF, Brazil, which presented a Pb(II) concentration of 2.66 mg L−1. The Pb(II) concentration in this wastewater was reduced to 2.49; 0.45 and 0.47 mg L−1 by application of Caryocar spp.; Manilkara spp.; and Tabebuia spp., respectively.

Brazilian sawdust samples (Caryocar spp.; Manilkara spp.; and Tabebuia spp.) have been used for Cr(VI) adsorption from water. The series of adsorption isotherms were adjusted to modified Langmuir equation. Thermodynamic data of interactions were studied by the calorimetric titration of Cr(VI) in aqueous solution. All liquid/solid interface adsorptions were entalpically and entropically driven. These sawdust samples were also used to remove chromium from tannery wastewater. The application of Caryocar spp.; Manilkara spp.; and Tabebuia spp. reduced the amount of chromium from 2.11 ± 0.18 mg L−1 to 1.15 ± 0.10; 0.29 ± 0.02 and 0.26 ± 0.02 mg L−1, respectively.

The objective of this work was to examine quantitatively the color changes of six clones of Hevea brasiliensis (IAN 717, IAN 873, GT 711, AVROS 1301, RRIM 600, and Tjir 16) and two cypresses ( Cupressus sp. and Cupressus glauca ) upon fungal attack. Samples were exposed to the fungi Gloeophyllum striatum and Phanerochaete chrysosporium according to ASTM D 2017. Wood color was measured in the L ∗ a ∗ b system. Changes in the colorimetric parameters were calculated by the difference between attacked and control samples. None of the rubberwood clones showed weight loss below 25% and therefore could not be classified as resistant, but clones AVROS 1301, RRIM 600, and Tjir 16 were borderline. Both cypresses were resistant to P. chrysosporium , but only Cupressus sp. was resistant to G. striatum . The red tint of all samples exposed to both fungi was slightly intensified (Δ a ∗ > 0), except for RRIM 600. The yellowish tint was intensified as well, except for RRIM 600 and Tjir 16 exposed to G. striatum . Samples attacked by G. striatum were darker than controls (Δ L ∗ P. chrysosporium were lighter (Δ L ∗ > 0). Color variation mean values (Δ E ∗ ) ranged from 3.98 to 12.33, attaining the levels appreciable to very appreciable color difference. Extraction of the attacked samples with ethanol–toluene plus hot water removed red and yellow chromophore pigments, causing color variations perceptible to the naked eye.

This paper aims to evaluate whether a thermal post-treatment can be applied to enhance the performance of oriented strandboard (OSB). Samples from 42 commercial OSBs were heat-treated at two temperature levels (190 and 220 °C) and for three heating times (12, 16, and 20 min) using a single opening hot-press. For comparison, control boards were kept untreated. These samples were exposed for eight months to outdoor weathering, and then their physical and mechanical properties were evaluated, as was their decay resistance against the brown-rot (Gloeophyllum trabeum [Persoon ex Fries] Murrill) and white-rot (Trametes versicolor [Linnaeus ex Fries] Pilat Murrill) fungi. The results indicated that the heat-treated samples maintained their mechanical properties at a much higher level after weathering than did the untreated ones. It was determined that the higher the treatment temperature, the better the residual mechanical properties. The proposed thermal treatment also slightly improved the decay resistance against the two evaluated fungi, but it was not enough to change the resistance class of the OSB.

The main objective of this research was to determine quantitatively the amount of structural sugar polymers (glucan, mannan, and xylan) and acid lignin, after decaying of a conifer wood Cupressus glauca Lam., exposed to brown-rot fungi Gloeophyllum trabeum (Persoon ex Fries) Murril. and Lentinus lepideus Fr. and white-rot fungi Trametes versicolor (Linnaeus ex Fries) Pilat and Ganoderma applanatum (Pers. ex Wallr.) Patouillard. Extractive and ash contents were homogeneous and showed low value. Chromatographic and spectroscopic techniques were important tools for detecting changes in the wood chemical composition. White-rot fungi showed two different class resistances with almost unchanged decay wood constituents. Brown-rot fungi removed the polysaccharides but not lignin. G. trabeum and L. lepideus had similar effects on chemical composition of cypress wood. This cypress wood showed lower mannan contents than xylan.

Woods of 36 tree species from the Brazilian Amazon forest have been extracted and analyzed by means of total hydrolysis. For each species, three trees were analyzed in duplicate. The sugars and other byproducts of hydrolysis were analyzed by HPLC. Uronic anhydrides and acid-soluble lignin were determined by colorimetric methods. Acid-insoluble lignin, ash, and extractive contents were analyzed gravimetrically. Each analysis was performed several times and the data were evaluated statistically. The average percentages for ash and extractives are presented. Quantitative data for sugars obtained by HPLC were recalculated for glucan, galactan, arabinan, and mannan contents. These data are presented together with quantitative data for acetyl groups, 5-hydroxymethyl-2-furfuraldehyde, levulinic acid, uronic anhydride, acid-soluble and -insoluble lignin as summative analysis data based on an ash- and extractive-free basis, where, in an ideal case, the data should sum up to 100%. The summative results obtained varied from 96.0% to 99.6%, which is very satisfactory.

Control and hot water treated particles of cypress ( Cupressus spp.) were used to manufacture cement-bonded particleboards (CBPB). Three replications were carried out for each treatment, totaling six single layered boards. Physical and mechanical properties of the boards were evaluated according to ASTM D 1037-96a [Annual Book of ASTM Standards, vols. 04–09. Philadelphia: American Society for Testing and Materials––ASTM, ASTM D 1037-96a, 1998] standard. The wood of cypress showed suitability as raw material for the manufacture of CBPB. All the properties of cypress CBPB were higher than the Bison HZ type building boards used as reference. The light color and easy wood processing of cypress wood are favorable parameters for panels manufacturing. The results corroborate those reported for CBPB using pine, rubberwood, acacia, babassu, and eucalyptus particles. The CBPB were also submitted to fungi decay resistance test according to ASTM D 2017-81 [Annual Book of ASTM Standards, vols. 04–09. Philadelphia: American Society for Testing and Materials––ASTM, 1994-e1. ASTM D 2017-81, p. 324–8] standard and exposed to the attack of Gloeophyllum trabeum (Persoon ex Fries) Murr. and Trametes versicolor (Linnaeus ex Fries) Pilat. Twelve specimens were tested for each treatment and the average weight loss was determined after 12 weeks of exposure. Laboratory tests showed that there was no measurable wood degradation (weight loss). Fungi mycelium did not even cover completely the surface of the specimens. CBPB when exposed to both brown- and white-rot fungi, rather than weight loss, showed weight gains ranging from 2% to 4%. Therefore, CBPB is technically suitable for exterior use where both moisture and favorable conditions for fungi development are present.

Six eucalypts species Eucalyptus camaldulensis Dehnh., E. citriodora Hook, E. cloeziana F. Muell, E. grandis Hill ex. Maiden, E. pilularis Sm., and E. urophylla S. T. Blake) and two clones of rubberwood ( Hevea brasiliensis (Willd ex Adr. de Juss) Muell. Arg.), planted in Brazil, were used to manufacture wood cement-bonded particleboard (CBWP). Boards measuring 450 × 450 × 13 mm were manufactured in a wood/cement/water ratio of 1:4:1, by weight; nominal density of 1.4 g/cm 3 and 4% of additive (CaCl 2 ·H 2 O) using a mixture of each eucalypts species (50%) and the two clones of rubberwood (25% of each). Three replications were fabricated for each treatment and the physical and mechanical properties of the boards evaluated according to ASTM D 1037-96a [Standard test methods for evaluating properties of wood-base fiber and particle panel materials. ASTM D 1037-96a, vol. 04.09. ASTM, 1998]. The results of modulus of elasticity ranged from 4090 to 4771 MPa. The results of modulus of rupture ranged from 5.8 to 6.4 MPa. Internal bond were similar to those found in the literature. Screw withdrawal values were up to 2020 N. The panels showed very good dimensional stability. The mixture of species and also the addition of calcium chloride have improved the physical and mechanical properties of the panels. Decay fungi tests were conducted according to the ASTM D 2017-81 [Standard test method for accelerated laboratory test of natural decay resistance of woods. ASTM D 2017-81, vol. 04.09. ASTM, 1994-e1. p. 324] for two representative wood-attacking fungi, a brown-rot fungus Gloeophyllum trabeum (Persoon ex Fries) Murrill and a white-rot fungus Trametes versicolor (Linnaeus ex Fries) Pilat. Twelve samples were tested and after 12 weeks of exposure the average weight loss was determined. The test indicated that CBWP was classified as “highly resistant” and the samples gained weight.

Chapas de partículas de cimento-madeira foram confeccionadas com a madeira de quatro clones de Hevea brasiliensis Müll. Arg. (seringueira): IAN 717, IAN 873, GT 711 e AVROS 1301. Confeccionaram-se as chapas na proporção de 1:4:1 (madeira:cimento:água) por peso e nas dimensões de 450 x 450 x 13 mm e densidade nominal de 1,4 g/cm³, com a adição de 4% de cloreto de cálcio di-hidratado (CaCl2.2H2O) como acelerador. Foram testadas partículas fervidas e não-fervidas dos quatro clones, totalizando oito tratamentos, sendo em cada um destes, com quatro repetições, avaliadas as propriedades mecânicas e físicas das chapas, segundo a norma ASTM D 1037 - 96a. De forma geral, os melhores resultados de propriedades físicas e mecânicas foram obtidos nas chapas com partículas do clone AVROS 1301. No teste de hidratação do cimento, a madeira de seringueira in natura foi classificada como de "inibição extrema", porém com a adição de CaCl2 o foi como de "baixa inibição". Essa madeira se mostrou tecnicamente viável à produção de chapas de cimento-madeira, independentemente do clone.

This research is part of a general study on the properties of oriented strandboard (OSB) using wood strands of species from Brazilian planted forests. The OSB industry is the latest wood related activity established in Brazil. In this particular part of the study, 80 mm long strands of Pinus taeda L. were bonded using two resin types (urea-formaldehyde and phenol-formaldehyde) at two levels of resin content (5% and 8%) to produce three-layer cross-aligned OSB to a face to core layer ratio of 1:2 and target density of 0.75 g/cm3. Physical and mechanical properties of the boards were evaluated according to ASTM standard D 1037-96a (1997) and the results compared to standards available as requirements for commercial structural panels. The results indicate that all the mechanical properties evaluated were above the requirements set forth by the Canadian standard CSA O437.0 (1993) for structural panels. The results of Janka hardness were in average 4 folds higher than the minimal requirements for Grade R-1 waferboard. Screw withdrawal values were also above the minimum required by grade M-3 of ANSI A208.1 standard (1993). Nevertheless, values of thickness swelling and water absorption were very high. The low dimensional stability may be related to the high density of the boards (“springback” effect) and also to the fact that no wax was used.

In this study, the biological resistance and physical–mechanical properties of laboratory made particleboard and flakeboard using natural and acetylated particles and flakes of cypress (Cupressus spp.), planted in Brazil, were examined. Boards with 10% urea–formaldehyde resin were pressed for 8 min at 160°C. The experimental design was a 22 complete factorial, with four replicates per treatment, totalling 16 single-layer panels of 550×500×13 mm with a mean density of 0.70 g cm −3 . The panels were cut into samples, and their physical and mechanical properties determined according to ASTM D 1037-96a standard. Cypress panels were tested in the laboratory for durability, according to ASTM D 2017-81. Control panels were classified as “resistant” when exposed to the brown-rot fungus, Gloeophyllum trabeum, while the acetylation process improved the resistance of the cypress panels, which were subsequently classified as “highly resistant”. The same effect was observed for specimens exposed to the white-rot fungus Trametes versicolor. Regarding mechanical properties, the manufactured cypress panels should be classified as grade M-3, according to ANSI A208.1, except for internal bond and modulus of elasticity of flakeboards and particleboards, respectively. Dimensional stability of flakeboards and particleboards was very low. Acetylated panels showed better physical but lower mechanical properties than the control panels. Swelling of acetylated cypress flakeboards, after 2 and 24 h of water immersion, was lower than the maximum required by EN 312-4 standards. Cupressus spp. wood was shown to be very suitable to be processed into reconstituted panels.

Conduziu-se este trabalho, com os objetivos de: avaliar a resistência natural de painéis reconstituídos e da madeira de Toona ciliata ao ataque de fungos por meio de ensaio acelerado de laboratório; caracterizar seus componentes anatômicos segundo IAWA; quantificar os valores de lignina solúvel e insolúvel; das amostras por hidrólise ácida e os parâmetros colorimétricos antes e após o ataque dos fungos, utilizando o sistema CIE-L*a*b*(1976). A madeira sólida foi classificada como moderadamente e altamente resistente ao fungo de podridão branca (Trametes versicolor) e parda (Gloeophyllum trabeum). Os painéis OSB foram resistentes e moderadamente resistentes à podridão branca e para a parda, foram altamente resistentes. A variação de espécies e partículas não teve efeito positivo nos tratamentos. Com relação à madeira, ambos os fungos apresentaram inibição, em razão da presença de resina fenólica. Os aglomerados foram classificados como moderadamente resistentes à podridão branca. Os tratamentos T2 (cedro) e T4 (cedro-eucalipto) foram resistentes, mas o T3 (cedro-pinus) não resistiu ao ataque do fungo de podridão parda. A resina uréia-formaldeído não inibiu os ataques como a fenólica. Anatomicamente, a espécie apresentou textura média, linhas vasculares retilíneas, cheiro agradável ao corte e superfície radial pouco lustrosa. Sua estrutura anatômica favoreceu a colonização das hifas dos fungos. Todos os tratamentos ocasionaram escurecimento, após o ataque do fungo G. trabeum, com variação total da cor. Observou-se que, com a perda de massa, houve aumento nos teores de lignina insolúvel, para todos os tratamentos, indicando que essa propriedade química é um fator determinante na resistência da madeira ao ataque dos fungos avaliados. 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.

Mahogany is one of the most valuable woods and was widely used until it was included in Appendix II of the Convention on International Trade in Endangered Species as endangered species. Mahogany wood sometimes is traded under different names. Also, some similar woods belonging to the Meliaceae family are traded as “mahogany” or as being of a “mahogany pattern”. To investigate the feasibility of the use of near infrared spectroscopy for wood discrimination, the mahogany (Swietenia macrophylla King.), andiroba or crabwood (Carapa guianensis Aubl.), cedar (Cedrela odorata L.), and curupixá (Micropholis melinoniana Pierre) woods were examined. Four discrimination models based on partial least squares-discriminant analysis were developed based on a calibration set composed of 88 samples and a test set with 44 samples. Each model corresponds to the discrimination of a wood species from the others. Optimization of the model was performed by means of the OPUS® software followed by statistical analysis software (Matlab®). The observed root mean square errors of predictions were 0.14, 0.09, 0.12, and 0.06 for discriminations of mahogany, cedar, andiroba, and curupixá, respectively. The separations of the species obtained based on the difference in the predicted values was at least 0.38. This makes it possible to perform safe discriminations with a very low probability of misclassifying a sample. This method can be considered accurate and fast.

Shredded newspaper, magazine, and office wastepaper, bonded with urea-formaldehyde (UF) and tannin paraformaldehyde (TP) adhesives both at 8% and 12% of resin solid contents, based on oven-dried weight of particles, were used to produce low-density boards in a series of laboratory scale experiments. Physical, mechanical and dimensional stability properties were analyzed according to ASTM D 1037-91. The target board density and thickness were 0.6 g/cm3 and 0.8 cm, respectively. Office wastepaper and newspaper UF and TP-bonded boards, at 12% resin level, had the best mechanical properties. Office wastepaper boards also exhibited the best thickness swelling properties. The dimensional stability properties of UF-bonded boards were better than the TP-bonded boards. In general, as resin level increased from 8% to 12% both MOR and MOE values increased. A comparison between UF and TP-bonded boards showed that the former performed better, at the same resin level.

RESUMO O objetivo do trabalho foi avaliar a resistência natural de chapas de partículas orientadas (OSB) confeccionadas com partículas de Hevea brasiliensis Müll.Arg. aderidas com as resinas sintéticas uréia- formaldeído (UF) e fenol-formaldeído (FF), a 5% e 8%, expostas a fungos xilófagos em condições de laboratório. No ensaio acelerado de laboratório as amostras foram submetidas ao ataque dos fungos de podridão-parda Gloeophyllum trabeum (Pers. : Fr.) Murril, Coniophora puteana (Schumach. : Fr.) P. Karst., Meruliporia incrassata (Berk. & M.A. Curtis) Murrill e também aos fungos de podridão-branca, Fomes annosus (Fr. : Fr.) Cooke, Trametes versicolor (L. : Fr.) Pilát, Ganoderma applanatum (Pers.) Pat., Bjerkandera fumosa (Pers. : Fr.) P. Karst. e Phanerochaete chrysosporium Burds. Dentre os fungos de podridão-parda, o Gloeophyllum trabeum causou a maior perda de massa nos corpos-de-prova testados. Dentre os fungos de podridão-branca, Trametes versicolor, Phanerochaete chrysosporium e Ganoderma applanatum causaram as maiores perdas de massa, sem diferença significativa para o Gloeophyllum trabeum. A resina FF proporcionou maior resistência à ação dos fungos nas chapas OSB, o mesmo fato ocorrendo com o maior teor de resina. O fungo Coniophora puteana foi altamente sensível ao tipo de resina aplicado, enquanto o Bjerkandera fumosa demonstrou reduzida ação nas concentrações mais altas de ambas as resinas. O fungo Fomes annosus apresentou degradação insignificante para todos os tratamentos de chapas OSB. ABSTRACT This work aimed to evaluate the natural durability of oriented strandboards (OSB) manufactured with strands of Hevea brasiliensis Müll.Arg. bonded with 5% and 8% of urea-formaldehyde (UF) and phenol-formadehyde (FF) resins, exposed to xilophagous fungi under laboratory conditions. In accelerated laboratory test decay, samples of OSB were exposed to the following fungi: the brown-rot fungi Gloeophyllum trabeum (Pers. ex Fries) Murr., Coniophora puteana (Schumach. : Fr.)P. Karst., Meruliporia incrassata (Berk. & M.A. Curtis) Murrill as well as the white-rot fungi Fomes annosus (Fr. : Fr.) Cooke, Trametes versicolor (L. : Fr.) Pilát, Ganoderma applanatum (Pers.) Pat., Bjerkandera fumosa (Pers. : Fr.) P. Karst. and Phanerochaete chrysosporium Burds. Among the brown-rot fungi, the Gloeophyllum trabeum was the most aggressive, showing the highest loss of mass. Trametes versicolor and Ganoderma applanatum confirmed the preference for broadleave species. All oriented strandboards at lower UF resin contents were more degraded by Phanerochaete chrysosporium, Trametes versicolor, Ganoderma applanatum, Merulia incrassata, Coniophora puteana and Gloeophyllum trabeum, with high rate of loss of mass. Coniophora puteana showed small loss of mass when FF resin was applied. Bjerkandera fumosa showed low loss of mass only at higher resin content. Oriented strandboards exposed to Coniophora puteana showed insignificant OSB degradation.

Oriented strandboard made of pine, cypress and rubberwood. This research evaluated the physical- mechanical properties of oriented strandboards (OSB) using strands of pine, cypress and a mixture of two clones, of rubberwood. The ratio of face to core layer was 1:2:1. Boards measuring 450 x 450 x 13 mm were bonded with 5% and 8% of urea-formaldehyde (UF) and phenol-formaldehyde (FF) resins, based on the dry weight of the particles, with density of 0.75 g/cm 3 . The boards were evaluated according to ASTM D 1037 and compared with CSA O437.0 and ANSI A.208.1 standards. In general, as the resin level increased, mechanical and physical properties also improved, and panels with 8% FF resin showed the best performance. Cypress OSB made with FF resin showed higher mechanical properties, except internal bond than required by aforementioned standards. OSB panels were also dimensionally unstable since water absorption and thickness swelling values were very high. The mechanical properties of rubberwood OSB were higher than required by CSA O437.0 and ANSI A.208.1, except for internal bond, since only panels bonded with 8% of FF resin met the requirements of the CSA O437.0 standard.