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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 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.

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.

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.

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.