Natural durability of Eucalyptus grandis and Bambusa vulgaris particleboards under accelerated fungi decay test [Durabilidade natural de painéis aglomerados confeccionados com Eucalyptus grandis e Bambusa vulgaris em ensaio de apodrecimento acelerado]
Stangerlin D.M.,Federal University of Mato Grosso |
de Melo R.R.,Federal University of Piauí |
Garlet A.,Laboratorio Of Produtos Florestais |
Gatto D.A.,Federal University of Pelotas
Ciencia Rural | Year: 2011
The knowledge about lignocellulosic compounds strength to the attack of microorganisms is essential for preventing deterioration and also for knowing the correct usage of the material. Accordingly it was evaluated the natural resistance of wood panels made of particles of wood (Eucalyptus grandis) and/or bamboo (Bambusa vulgaris) to decay fungi. Particleboards were produced in laboratory, each of them with dimensions 50x50x0.95cm and density pre-set at 0.70g cm -3, in proportions of 100:0, 75:25, 50:50, 25:75 and 0:100 of wood and bamboo, respectively. The particles mass represented 91% of the dry mass of each panel while the remainder was formed by the urea-formaldehyde adhesive (8%) and paraffin (1%). The panels were tested in the laboratory and Gloeophyllum trabeum (brown rot) and Trametes versicolor (white rot) were used to determine the natural resistance to attack by wood decay fungi. It was observed that panels which were made with a mixture of particles of wood and bamboo were less resistant to attack by decay fungi. Panels that were made from bamboo or wood only showed similar biological resistance. Among fungi, T. versicolor was the one that attacked panels more severely.
Effect of nondestructive testing of laminations on the bending properties of glulam beams made from louro -vermelho (Sextonia rubra) [Efeito da classificação não destrutiva das lâminas sobre as propriedades de flexão de vigas mlc produzidas com louro-vermelho (Sextonia rubra)]
Teles R.F.,Faculdade da Terra de Brasilia |
del Menezzi C.H.S.,University of Brasilia |
de Souza M.R.,Laboratorio Of Produtos Florestais |
de Souza F.,Institute Ciencias Agrarias
Cerne | Year: 2010
This work aims to assess the bending properties of glued laminated timber beams (glulam) manufactured with species louro-vermelho (Sextonia rubra). Laminations were nondestructively tested using the transverse vibration method (EMlam). Then 10 glulam beams were manufactured and tested in static bending according to ASTM D 198 standard, having modulus of elasticity (EM), modulus of rupture (fM), and bending moment (M) determined. The finished beams were also tested by the transverse vibration method (EMvt). It was noted that the EMvt value was only 2% lower than the EM value. Using laminations with a high modulus of elasticity did allow effective gain in stiffness. Therefore, results indicate that the transverse vibration method is a valid, reliable technique both for testing glulam laminations and for assessing stiffness in finished beams. Bending properties in glulam beams were influenced by the stiffness of constituent laminations.
De Melo R.R.,Federal University of Mato Grosso |
Soares Del Menezzi C.H.,University of Brasilia |
De Souza M.R.,Laboratorio Of Produtos Florestais |
Stangerlin D.M.,Federal University of Mato Grosso
Floresta e Ambiente | Year: 2013
The quality of veneer from Schizolobium amazonicum was evaluated assessing physical (density, porosity, moisture content and dimensional stability), mechanical (bending strength and shear strength), nondestructive (stress wave), chemical and surface (image analysis, color, roughness and wettability) properties. The results indicated that the Schizolobium amazonicum veneer presented whitish-gray color, low density, high porosity, low dimensional stability, low roughness and high wettability. The stress wave dynamic modulus of elasticity and veneer density were significantly correlated with the mechanical properties of the veneer. These parameters can be used as indicators for assembling strategies in the manufacturing of laminated composites.
Bernal R.A.,BioFIG |
Coradin V.,Laboratorio Of Produtos Florestais |
Camargos J.,Laboratorio Of Produtos Florestais |
Costa C.,Brazilian National Council for Scientific and Technological Development |
IAWA Journal | Year: 2011
Woods from an important group of Lecythidaceae species called "tauari" can hardly be identified in the field by their gross and general features. In this study we show that, when properly delimited to the genera Allantoma, Cariniana and Couratari, wood anatomical characteristics can be used to identify the species known as "tauari", even though it is not possible to separate all species. In addition to anatomical characters, wood colour is an important character to help distinguish species of Cariniana and Allantoma from species of Couratari. Detailed wood anatomical descriptions from "tauari" woods Allantoma, Cariniana and Couratari are given and a table with diagnostic differences is presented. Common characters of this group are axial parenchyma in narrow continuous bands, prismatic crystals in chambered axial parenchyma cells and silica bodies in ray cells. Microscopic features that help in species identification are: fibre pitting (minutely or distinctly bordered), traumatic intercellular canals, average vessel diameter, vessel element length, axial parenchyma strand length, and ray height and width.
Teixeira D.E.,Laboratorio Of Produtos Florestais |
De Melo J.E.,University of Brasilia |
Anacleto J.E.,Laboratorio Of Produtos Florestais
Scientia Forestalis/Forest Sciences | Year: 2014
Bonding strength quality tests were conducted on six Brazilian tropical timber species using four types of commercial resins, three PVA bases and one phenol-resorcinol, aiming at their application as structural members and laminated furniture parts. The wood sampling was made at random and conditioned to 12% moisture content at the Forest Products Laboratory (LPF) before bonding. The ASTM D 905-08 (2008) standard was used to bond the timber blocks to a gramature of 300 g/m2. The species tested were: amapá (Brosimum parinarioide), amapá-doce (Brosimum potabile), breu sucuruba (Protium heptaphyllum), muiratinga (Maquira sclerophylla), tauari (Couratari stellata), and tacacazeiro (Sterculia speciosa). The timbers glued with phenol-resorcinol resin (PR) presented the higher shear strength and wood failure. The resin type A602 produced the strongest bond among those blocks glued with PVA type resins. All wood species laminated and bonded with PR presented higher shear strengths than those of the solid timber.
Braga J.W.B.,University of Brasilia |
Pastore T.C.M.,Laboratorio Of Produtos Florestais |
Coradin V.T.R.,University of Brasilia |
Camargos J.A.A.,University of Brasilia |
And 2 more authors.
IAWA Journal | Year: 2011
Near infrared spectroscopy (NIRS) has been shown effective as a tool for identifying Swietenia when tested as laboratory-processed powder, but testing such powdered wood is not readily adaptable to the fieldidentification of wood. This study explored the efficacy of a fiber optic NIRS scan of solid wood surfaces to separate Swietenia macrophylla King, Carapa guianensis Aubl., Cedrela odorata L., and Micropholis melinoniana Pierre. Transverse, radial, and tangential surfaces were scanned to determine if the surface from which data were collected influenced the spectra recorded. Surfaces were scanned before and after removing the oxidized surface layer of the blocks to test effects of exposure on the spectra. Partial least squares for discriminant analysis models were developed for each taxon separately, based on a calibration set composed of at least 67 samples and a test set with at least 45 samples. The anatomical surface scanned, but not the presence of an oxidized layer, influenced the spectra for each species, necessitating the comparison of the same planes of section. The discriminant models showed small errors for each species, indicating that reliable identifications can be made with NIRS of solid wood surfaces in these species.
Photodegradation of two tropical wood species: Jatobá (Hymenaea courbaril) and tauari (Couratari oblongifolia) submitted to ultraviolet radiation [Fotodegradação de duas espécies de madeiras tropicais: Jatobá (Hymenaea courbaril) e tauari (Couratari oblongifolia) submetidas à radiação ultravioleta]
Costa J.A.,University of Brasilia |
Goncalez J.C.,University of Brasilia |
Camargos J.A.A.,Laboratorio Of Produtos Florestais |
Gomes I.A.S.,University of Brasilia
Cerne | Year: 2011
The objective of this study was to follow the process of photodegradation of the natural color of wood surface of two tropical species when exposed to ultraviolet radiation. It were used the wood of jatobá (Hymenaea courbaril) with reddish brown coloration, and tauari (Couratari oblongifolia) with yellowish olive coloration. Samples of these woods were subjected to four cycles of ultraviolet radiation (UV) amounting to a total of 168 hours of irradiation and at 350 nm of wave length. Changes of the woods natural color, indicative of the photodegradation process, was monitored by spectrocolorimetry. Both species underwent changes in color caused by photodegradation, since the irradiation caused darkening which was quantifi ed by the intensity of reflected light. Tauari demonstrated greater resistance to UV radiation and jatobá showed greater tendency to redden up. Both species were classifi ed as woods with very appreciable variation in color.
Relationships among chemical properties, physical and energy wood properties of five Cerrado species [Relações entre propriedades químicas, físicas e energéticas da madeira de cinco espécies de cerrado]
do Vale A.T.,University of Brasilia |
Dias I.S.,University of Brasilia |
Santana M.A.E.,Laboratorio Of Produtos Florestais
Ciencia Florestal | Year: 2010
This work aimed at characterizing and evaluating the influence of the chemical properties (lignin, holocellulose and extratives contents) of five Cerrado wood species (Pterodon pubescens, Dalbergia miscolobium, Sclerolobium paniculatum, Stryphnodendron adstringens and Vochysia thyrsoidea) on density and shrinkage wood; gravimetric yield and apparent density of charcoal. The samples were collected in area of forest management in Brasilia (Brazil, DC), from three trees of each species, thus making a total of 15 samples. No significant differences among species were detected for wood extractive content and charcoal gravimetric yield. Pterodon pubescens, Dalbergia miscolobium and Sclerolobium paniculatum stood out by presenting, respectively, the highest basic density (0.82, 0.80 and 0.78 g/cm3); the greatest content of lignin (31.74, 32.31 and 31, 42%), the highest charcoal apparent density (37, 43 and 37%). On the other hand, Stryphnodendron adstringens and Vochysia thyrsoidea stood out by presenting, respectively, the highest content of holocellulose (72.22% and 74.84). The lignin showed positive and significant correlation with the basic density and wood charcoal apparent density; showed no significant correlation with the volumetric shrinkage neither gravimetric yeild. The holocellulose content showed negative and significant correlation with the density of the wood, and charcoal apparent density. The total extractives not provided with any significance studied of variables.
Influence of the specimen size and test speed in static bending strength of three tropical wood species [Influência das dimensões dos corpos de prova e da velocidade de ensaio na resistência à flexão estática de três espécies de madeiras tropicais]
de Melo J.E.,University of Brasilia |
de Souza M.R.,Laboratorio Of Produtos Florestais |
da Costa A.F.,University of Brasilia
Ciencia Florestal | Year: 2015
This paper discusses the influence of different test speeds and specimen sizes, free of defects, in determining the bending strength of three Brazilian woods. Its importance lies in the possibility of establishing methods of characterization with smaller specimens and higher speeds, resulting in time saving and cost reduction in transport, without loss of quality and precision in results. Traditionally, tests with small variations of speed and specimen size have been little discussed, possibly due to the lack of interest in changing methodologies which are already established. The methodology used here involved the static bending with moisture content at 12%, five specimen sizes and three test speeds. The species characterized were: cumaru (Dipterix odorata), jequitibá (Allantoma lineata) and quaruba (Vochyisia guianensis). References on dimensions and speeds were selected based on the Comisión Panamericana de Normas Técnicas (COPANT 555/73). These standards establish procedures for determining the physical and mechanical properties of wood species, free of defects, using small specimen sizes. The results showed a significant influence of specimen size and no influence of the velocities in the tests for determining the bending properties of the species featured. In conclusion, to maintain compatibility with the already published results, using this standard is not recommended to change the specimen dimensions but the current test speed can be increased within the limits studied. © 2015, Universidade Federal de Santa Maria. All rights reserved.
Relation between humidity values and the dielectric constant of species of amazonian forest woods during the drying process [Relação entre o teor de umidade e a constante dielétrica de espécies de madeira da amazônia durante o processo de secagem]
Crisostomo M.C.,University of Brasilia |
Gouveia F.N.,Laboratorio Of Produtos Florestais |
Da Costa A.F.,University of Brasilia
Revista Arvore | Year: 2016
The objective of this study was to determine the relation between dielectric constant and the humidity of six species of wood, by the construction of a capacitor. The material used was non commercialized Amazonian wood, but with high abundance and domination in the National Forest of Tapajós – State of Para, such as: Albizia duckeana (fava-paricá), Brosimum sp. (amapá-doce), Chamaecrista scleroxylon (pau-santo), Qualea dinizii (mandioqueira-rosa), Trattinnickia burserifolia (amescla) and Swartzia laurifolia (gombeira). The samples used to determinate the dielectric constant were made with the dimensions of: 4.5 x 4.5 x 1 cm, defined by preliminary tests made at Forestry Products Laboratory (LPF). The values of capacitance were collected by the construction of a capacitor using a digital multimeter, copper wires, and aluminum plates; and the values were collected eight times with intervals of one hour, during the drying process, starting at saturated mass to constant mass. Therefore, with the collected data the regression curves were established between humidity values and the dielectric constant of wood, which showed a strong correlation between the two variables, showing the direct and proportional influence of the humidity over the dielectric constant. Due to the inexistence of direct relation between specific mass and dielectric constant of the studied species, we suggest new studies to explain the relation between those characteristics. © 2016, Sociedade de Investigacoes Florestais, All rights reserved.