Scielo RSS <![CDATA[Maderas. Ciencia y tecnología]]> vol. 17 num. 1 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<strong>Comunicación científica</strong>: <strong>Avances en la profesionalización</strong>]]> <![CDATA[<strong>Mid-infrared spectroscopy and dynamic mechanical analysis of heat-treated obeche (</strong><em><b>Triplochiton scleroxylon</b></em><strong>) wood</strong>]]> The chemical structure change and rheological behaviour of heat-treated Obeche (Triplochiton scleroxylon) wood were investigated. Wood samples were treated at 160 and 200°C for 30, 60 and 120 minutes. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and dynamic mechanical analysis (DMA) were employed to characterize the chemical structure and rheological property of the heat-treated wood, respectively. Infrared data showed that there was a reduction in the number of hydroxyl groups (one of the factors normally attributed to water absorption) of heat treated wood relative to the control samples. The relative cellulose crystallinity increased slightly which may be one of the factors contributing to the stiffness of the heat-treated wood. The latter increases with increasing treatment temperature and time. The rheological properties of the wood samples were tested while submerged in N-methyl-2-pyrrolidone solvent under saturated conditions. DMA results showed that the increasing heat treatment time caused an increase in the glass transition temperature relative to the control sample, irrespective of the treatment temperature. Therefore, heat treatment at moderately high temperatures (160 and 200°C) showed an interesting potential which could be used to reduce water absorption and improve flexural modulus of Obeche wood. <![CDATA[<strong>Air permeability of sugi (</strong><em><b>Cryptomeria japonica</b></em><strong>) wood in the three directions</strong>]]> To investigate the air permeability of sugi (Cryptomeria japonica) and the effect of grain directions on it, the air permeabilities of air-dried sugi sapwood and heartwood were determined along the three material directions of wood. The value of the longitudinal permeability was the highest and that of the radial permeability was the lowest. The permeability of heartwood was about an order of magnitude less than the permeability of sapwood in the same direction. The ratio between the tangential and radial permeability was approximately 10, which was similar to softwoods that have impermeable rays. These results suggest that sugi has ray tissues that are either impermeable or have very low permeability. The radial permeability of sugi was much lower than that of Pinus, Sequoia, Juniperus, Abies, and Tsuga measured with gases reported in the literature, indicating that sugi is one of the least radially permeable softwoods. These findings explain the reasons for the difficulties encountered in the drying and chemical treatment of sugi (Cryptomeria japonica). <![CDATA[<strong>Fungicidal effect of Lippia alba essential oil on a white-rot fungus</strong>]]> Lippia alba is a plant that has antifungal activity against Aspergillus, Penicillium and Trichoderma genera as well as against human pathogenic microorganisms; however, there are no records on its effect on basidiomycetes which are responsible for white rot of wood. The objective of this study was to evaluate the antifungal activity of L. alba for the control of the white-rot fungus Pleurotus ostreatus. From L. alba leaves, essential oil (EO) was extracted by hydrodistillation, alcoholic extract (AE) was obtained through alcoholic maceration, and aqueous extract (QE) from aqueous infusion. Each extract was added to several culture media to evaluate the fungicidal effect on P. ostreatus. AE and QE do not have fungicidal activity. P. ostreatus does not survive EO when concentrations are higher than 1,0 mL L-1 in malt extract liquid culture medium, or higher than 9,0 mL L-1 in particulate sawdust solid culture medium. The physical state of the cultivation medium affects the fungicidal action of EO. In surfaces subject to greater volatility, the minimum fungicidal concentration of the EO is 25,0 mL L-1. Altogether, L. alba EO is a potential alternative of biological control of basidiomycetes of white rottenness in wood. <![CDATA[<strong>Studies on the loss of gloss of shellac and polyurethane finishes exposed to UV</strong>]]> Wood finishes protect the surface of wood from external agents, enhance its looks and improve its gloss (luster). On constant external exposure, UV rays gradually degrade the film coating resulting in loss of gloss. In this study, two commonly used finishes namely spirit shellac and polyurethane finish were used to investigate the pattern of loss of gloss due to UV interference. Two coatings of polyurethane (PU) and spirit shellac finish were applied on the surface of eucalyptus samples. The gloss levels of these and unfinished samples were monitored for different times of exposure of them to UV light. Gloss was measured at 600 gloss head using a Tri micro gloss meter regularly for 20 hours durations of UV exposure. Observations and analysis revealed that the natural gloss of uncoated samples of eucalyptus were least affected on UV exposure with only 8,3%-10% loss in gloss. The PU and shellac coated surfaces also showed very little reduction in gloss (6,9%-15,4%) most of which happened in the first 40 hours of exposure. Thus both the finishes in this study were found effective to a good extent in maintaining the gloss of the finished surface against exposure to UV light. <![CDATA[<strong>Effects of nano-clay particles and oxidized polypropylene polymers on improvement of the thermal properties of wood plastic composite</strong>]]> In this study, the effects of oxidized polypropylene, as a compatibilizer, and Nano-clay particles in improving the thermal properties of wood plastic composites are investigated. For this purpose, polypropylene polymer was oxidized in the vicinity of the air oxygen for 2 hours. Then, in order to produce the samples, Nano-clay particles at three levels (0%, 2% and 4%) were mixed with wood fibers, polypropylene polymer and the compatibilizer. Finally, the samples with thickness of 2mm and dimensions of 15×15cm were made by using hot press. For more precise investigation, the morphology of wood plastic composites was studied by using X-rays diffraction and electronic microscope images. Thermal properties of the composites were evaluated through thermal and differential analyses. The results of the thermal tests demonstrated that the addition of oxidized polypropylene and Nano-clay particles significantly improve the thermal properties of wood plastic composites. Furthermore, increment of Nano-clay particles content additionally improves thermal stability of the composites and also reduces the released heat amount during the thermal degradation. In addition, TEM images showed that the dispersion of Nano-clay particles in the composite has an intercalation structure. This subject also verified by the X-rays diffraction and it is an evidence of better thermal stability of the achieved wood plastic composites. <![CDATA[<strong>Decay and termite resistance of particleboard manufactured from wood, bamboo and rice husk</strong>]]> The resistance of particleboards, made from wood, bamboo and rice husk, to fungi and termites was evaluated. Panels were composed of 100% wood (Eucalyptus grandis), 100% bamboo (Bambusa vulgaris), 100% rice husk (Oryza sativa), 50% wood and 50% bamboo; and 50% wood and 50% rice husk. Panels exposed to the decay the brown-rot fungus (Gloeophyllum trabeum, and the white- rot fungus (Trametes versicolor), and, in a choice feeding trial, to termites (Nasutitermes corniger). The rice husk particleboards had the highest resistance of all samples and the bamboo particleboards had the lowest resistance. T. versicolor fungi produced a larger mass loss in the particleboards than did G. trabeum. <![CDATA[<strong>The effect of nano-zinc oxide on particleboard decay resistance</strong>]]> The aim of this study was to investigate the decay resistance of particleboards treated with nano- zinc oxide against the white-rot fungus Trametes versicolor and the brown-rot species Coniophora puteana. The nanomaterial was used for manufacturing particleboards at 5, 10 and 15% wt based on the glue dry weight. The soil block decay test was performed according to ASTM D 1413 (2007) using a 12 weeks incubation period. The results showed that all treated boards had good resistance against the decay fungi and the weight loss decreased in the samples with increasing nanomaterial loading. The threshold level of treated boards against fungal decay was obtained about 21% and 17% nano-ZnO against C. puteana and T. versicolor, respectively. Therefore, it had a positive effect on increasing particleboard resistance against the fungi. The maximum decay resistance (or minimum weight loss) occurred in the samples containing 15% zinc oxide nanoparticles. <![CDATA[<strong>Characterization of two cellulosic waste materials (orange and almond peels) and their use for the removal of methylene blue from aqueous solutions</strong>]]> The ability of orange peels (OP) and almond peels (AP) as adsorbents for the removal of a dyestuff, namely methylene blue (MB) from aqueous solutions has been studied. After their characterization by different techniques (elemental analysis, biochemical analysis, IR spectroscopy, thermogravimetric analysis, scanning electron microscopy, mercury porosimetry), adsorption kinetics of the dye have been investigated using common kinetic models cited in the literature: first order and pseudo-second order. The correlation coefficient has showed that the pseudo-second order kinetic equation best describes the adsorption kinetics for the tested materials. The experimental equilibrium data have been analyzed using linearized forms of Langmuir and Freundlich isotherms. The Langmuir isotherm was found to provide the best theoretical correlation of the experimental data whatever the biosorbents tested. Using the equilibrium coefficients obtained at different temperatures, various thermodynamic parameters such as ∆G°, ∆H°, ∆S° have been calculated. The thermodynamics of MB/OP and MB/AP systems indicated spontaneous and endothermic process. It was concluded that an increase in temperature results in a higher MB loading per unit weight of OP or AP. <![CDATA[<strong>Adaptation of the tween 80 assay with a resolution V fractional factorial design and its application to rank </strong><em><b>Ophiostoma</b></em><strong> fungi with wood extractive degrading capabilities</strong>]]> Wood extractives in radiata pine are the source of the observed pitch problems in the pulp and paper industry. Various methodologies have been studied and used to reduce or eliminate their negative effects. A biological treatment with albino fungi of the Ophiostoma genus, fungi that degrade the lipidic components of extractives, has been proposed as a more environmentally friendly alternative for pitch degradation. The current methods used to search for Ophiostoma albino strains with the highest degradation rates of wood extractives are labor intensive and require a large amount of resources. The Tween 80® Opacity test, an assay designed to measure lipolytic enzyme activity in filamentous fungi, was studied to verify the feasibility of its application as a methodology to rank Ophiostoma albino strains with deresination capabilities. The Tween 80® Opacity Test was first characterized by implementing a non-replicated 2k-p fractional factorial design of resolution V for a 5 factors with 16 treatments and then to study the effect of the fungus species on the lipolytic enzyme activity; a randomized one factor general factorial design was conducted. The incubation temperature; antibiotics presence; and Tween 80®, CaCl2, and peptone concentrations were investigated in the first experiment. The Ophiostoma species effect was studied in the second experiment. In both experiments, the halo area size, which was formed by the fatty acid-calcium complex precipitate, was the response variable. The results demonstrated the effectiveness of the Tween 80® opacity test to measure the lipolytic enzyme activity of Ophiostoma albino strains. Similarly, the incubation temperature and the concentrations of Tween 80®, CaCl2, and bacteriological peptone had the highest statistically significant effect on the response variable. In addition, our data demonstrated that the albino strains from the specie O. floccosum exhibited the highest rate of lipolytic enzyme production. <![CDATA[<strong>Furanic copolymers with synthetic and natural phenolic materials for wood adhesives - a maldi tof study</strong>]]> The structure of traditional, linear phenol-formaldehyde (PF) resins and phenol-furfural (P-Furan) resins has been investigated by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectroscopy. The structure of a variety of oligomers has been obtained and the structures present in each of the two types of resins related to the reagent used either formaldehyde or furfural. The oligomers type and species distribution appeared rather different for each case. Comparison of a P-Furan resin with a Mimosa tannin-Furan resin showed some differences. This latter shows a greater proportion of self-condensed fuanic oligomers due to the manner in which it is prepared starting from furfuryl alcohol. Several different Tannin-Furan oligomers were also observed by MALDI TOF analysis. <![CDATA[<strong>Alternative compositions of oriented strand boards (OSB) made with commercial woods produced in Brazil</strong>]]> This work aimed to investigate the feasibility of using and mixing Toona ciliata, Eucalyptus urophylla/grandis and Pinus oocarpa woods in OSB production. Three one- species and four mixed-species combinations were compared. Layer structure varied by positioning different wood species in the surface and core of the panels. Phenol- formaldehyde (PF) adhesive was applied at 9% for all OSB panels. Three-layer mats with mass proportion of 25/50/25% for surface/core/surface were produced. Pressing time was 8 min, under a 4 MPa pressure and temperature of 180°C. Physical and mechanical properties were evaluated and compared to EN (300) commercialization standard. Most OSB panels did not fully attain such requirements. OSB panels made with Eucalyptus urophylla/grandis and Pinus oocarpa woods have potential to be commercialized as OSB/1 and OSB/2 types, respectively. Among panels made with T. ciliata wood, those produced with this species in the surface and Eucalyptus urophylla/grandis wood in the core met the requirements established for OSB/1 commercialization. Eucalyptus wood has great potential to substitute Pinus wood in OSB production. The utilization of T. ciliata wood for OSB production decreased mechanical performance, but remarkably enhanced water resistance properties. <![CDATA[<strong>Mejoramiento de la productividad en una industria maderera usando incentivo</strong> <strong>remunerativo</strong>]]> Se estudió el efecto en la productividad de la elaboración de blanks a partir de la implementación de un modelo de incentivo salarial del tipo Improshare, dirigido al personal de una empresa chilena de remanufacturado de maderera que produce molduras y marcos de puerta (ayudante, operador medio y operador máster), para lo cual se compararon dos periodos de tiempo, antes (19 meses) y después (21 meses) de la implementación de la política de incentivo. Los resultados mostraron diferencias estadísticamente significativas en la productividad lograda entre periodos que superó el 10%. Se midió el beneficio promedio de la remuneración de los trabajadores, que llegó a más del 10% y el ahorro de la empresa llegó al 4,6% de la unidad monetaria definida, sin que se haya visto afectada la tasa de accidentabilidad. Lo anterior refuerza lo señalado por diferentes autores que concuerdan que este tipo de herramientas contribuye a mejorar la productividad del proceso e incrementar el salario del trabajador. Su implementación como política salarial en la industria maderera, aporta significativamente a los desafíos de una organización por mantenerse competitiva, así como mejorar la remuneración del trabajador en base a una relación de beneficio mutuo con la empresa.<hr/>We studied the effect on productivity resulting in the blanks elaboration from the implementation of a salary incentive model of Improshare type for staff working group in a sawnwood mill company producer remanufacturing moldings and door frames (assistant, operator and operator master), for which two time periods were compared, before (19 months) and after (21 months) of incentive policy implementation. The results show statistically significant differences in the productivity between periods, of more than 10%. The average benefit of the workers compensation was measured, it reached more than 10% and the savings to the company reached 4,6% of defined monetary unit, without affecting the accident rate. This reinforces the point made by different authors that this kind of tool improves the productivity of the process and increases wages. Its implementation as compensation policy in the lumber industry contributes significantly to the challenges that an organization faces to remain competitive and improve workers compensation based on a mutually beneficial relationship with the company. <![CDATA[<strong>Physico-mechanical properties of plywood bonded by nano cupric oxide (CuO) modified pf resins against subterranean termites</strong>]]> Nano CuO and alkane surfactant modified phenol Formaldehyde (PF) resins were applied to manufacture plywood, and physical and mechanical properties, such as shear strength, tensile property, modulus of rupture (MOR), modulus of elasticity (MOE), as well as termite resistance were evaluated. The result showed that the combination of nano CuO and alkane surfactantplayed different effect on tensile strength, and especially on shear strength as evaluated at different test conditions. But it was confirmed to improve the water resistance of treated plywood specimens. The introduction of nano CuO and surfactant did not influence the flexural properties significantly by statistically. The result of termite tests indicated that the weight loss decreases gradually from 31,12% to less than 10,37%, and the mortality increases from 32,61% to higher than 86,35%. And the AWPA rating also rises from 4 (very severe attack) to 7 (moderate attack). <![CDATA[<strong>Estudio comparativo entre fluorescencia de rayos X y reflectancia difusa de infrarrojos cercanos para la determinación de la retención en madera impregnada con arseniato de cobre cromatado</strong>]]> Se realizó un análisis comparativo de la precisión de los resultados en la determinación de la retención de óxidos de cobre, cromo y arsénico en madera impregnada con arseniato de cobre cromatado entre fluorescencia de rayos X y espectrometría de reflectancia difusa de infrarrojos cercanos. Los resultados de la calidad de las predicciones fueron comparados entre sí y con valores de retención obtenidos experimentalmente por método gravimétrico, absorción atómica y por cenizas resultantes de su calcinación. Los resultados del coeficiente de determinación del análisis de regresión entre la intensidad de fluorescencia de rayos X de las líneas K-Alpha y entre el espectro de reflectancia difusa de infrarrojos con respecto a la retención medida por métodos convencionales se encontraron en un rango de 0,909 a 0,986. Los resultados obtenidos pueden ser considerados aceptables para fines predictivos o incluso adecuados para propósitos de control de calidad. A su vez, al ser comparados por sus niveles de error de estimación, estos resultados fueron mejores que los obtenidos por otros estudios similares.<hr/>This paper evaluated the precision of predictions for chromated copper arsenate preservative retention in wood using X-ray fluorescence and near infrared diffuse reflectance. The quality of the predictions were compared with each other and with retention values obtained experimentally by gravimetric method, atomic absorption and total ash content. Coefficients of determination between the K-Alpha fluorescence intensities and near infrared diffuse reflectance with regard to conventional methods were between 0,909 and 0,986. The results can be considered acceptable for predictive purposes or even good for quality control purposes. In turn, the prediction errors were better than obtained by several studies. <![CDATA[<strong>Compression and flexural properties of finger jointed mango wood sections</strong>]]> In this paper, an attempt was made to assess the effectiveness of finger jointing in utilising mango wood sections for various end uses like furniture. The study was based on the estimation of Modulus of elasticity and Modulus of rupture under static bending and Maximum Crushing Stress and Modulus of elasticity under compression parallel to grain of finger jointed sections and comparing them with the values measured for clear wood sections from the same lot. For joining the sections, the Poly Vinyl Acetate and Urea Formaldehyde adhesives were used. It was found that the Modulus of elasticity of the sections joined by either adhesive showed significantly better values than that of unjointed clear wood sections. The Modulus of rupture values of sections joined with Urea Formaldehyde were similar to those of unjointed clear wood sections. However, sections jointed with Poly Vinyl Acetate adhesive exhibited lower Modulus of rupture. Under compression, the parameters of the jointed sections joined with either adhesive were either similar or better than those of the unjointed clear wood sections. The study demonstrates the utility of finger jointing of mango wood sections for furniture parts especially with the Urea Formaldehyde adhesive. <![CDATA[<strong>Effect of Albino </strong><em><b>ophiostoma</b></em><strong> strains on </strong><em><b>Eucalyptus nitens </b></em><strong>extractives</strong>]]> Wood extractives promote pitch formation during pulp and paper manufacturing. To date, this problem has been controlled by extended storage of the chips and/or chemical additives. Biotreatment of the wood prior to pulping provides an alternative that not only decreases the negative impact of the extractives but may also improve the kraft pulping efficiency. This initiative seeks to verify the quantity and chemical composition of Eucalyptus nitens wood extractives following biotreatment with three albino fungi species (Ophiostoma floccosum, Ophiostoma piceae and Ophiostoma piliferum). Eucalyptus nitens wood chips were sprayed with spore suspensions of Ophiostoma piliferum, Ophiostoma piceae and Ophiostoma floccosum albino strains (1 × 10(8) spore concentration). After 7 and 21 days of fungal treatment, the extractive content was determined via Soxhlet extraction with an 80:20% n-hexane:ethyl acetate solvent mixture. The Ophiostoma floccosum F1A94, Ophiostoma piliferum F2D8 and Ophiostoma piceae F2A68 strains proved to be most capable of bioreduction with reductions of 35,1%, 33,2% and 29,3%, respectively. The chemical composition of the extract was analyzed via gas chromatography coupled with mass spectrometry, which demonstrated that most of the tested strains could reduce the β- sitosterol content. <![CDATA[<strong>Evaluation of physical and mechanical properties of wild cherry wood heat-treated using the thermowood process</strong>]]> The aim of this study is to determine the change of some physical properties (oven-dry density, weight loss, swelling and anti-swelling efficiency) and mechanical properties (compression strength parallel to grain, bending strength, modulus of elasticity in bending, janka-hardness (cross-section, radial, tangential), impact bending strength and tension strength perpendicular to grain) of wild cherry woods after heat treatment under different durations. Specimens are exposed to temperature levels of 212°C for time spans of 1,5 and 2,5 h. Based on the findings in this study, the results showed that oven-dry density, swelling, compression strength parallel to grain, bending strength, modulus of elasticity in bending, janka-hardness (Cross-section, Radial, Tangential), impact bending strength and tension strength perpendicular to grain values decreased with increasing treatment time. <![CDATA[<strong>Mechanical properties of chemically modified portuguese pinewood</strong>]]> To turn wood into a construction material with enhanced properties, many methods of chemical modification have been developed in the last few decades. In this work, mechanical properties of pine wood were chemically modified, compared and evaluated. Maritime pine wood (Pinus pinaster) was modified with four chemical processes: 1,3-dimethylol-4,5-dihydroxyethyleneurea, N-methylol melamine formaldehyde, tetra- alkoxysilane and wax. The following mechanical properties were assessed experimentally: Modulus of elasticity measured statically, stiffness stabilization efficiency in different climates (30 and 87% of relative humidity), modulus of rupture, work maximum load, impact bending strength, compression, tensile and shear strength at indoor conditions (65% of relative humidity). In both types of active principle of modification, cell wall or lumen fill, no significant changes on the bending stiffness (modulus of elasticity) were found. In the remaining properties analysed significant changes in the modified wood-material took place compared to unmodified wood control: - Cell wall modification was the most effective method to achieve high stiffness stabilization efficiency (up to 60%) and also increased compression strength (up to 230%). However, modulus of rupture, tensile, shear and the impact bending strength were reduced by both resins, but in a varying extent, where the N-methylol melamine formaldehyde endured less reduction than 1,3-dimethylol-4,5-dihydroxyethyleneurea resin. In the latter, reduction up to 60% can take place. - In the lumen fill modification: tetra-alkoxysilane has no effect in the mechanical properties. Although, a slight increase in shear strength parallel to the grain was found. Wax specimens have shown a slight increase in bending strength, compression, tensile and shear strength as well as in the absorption energy capacity. <![CDATA[<strong>Influencia de la granulometria de la muestra en la discriminación de especies de </strong><em><b>Salix </b></em><strong>por infrarrojo cercano</strong>]]> En Brasil, las especies cultivadas del género Salix son de gran importancia en la artesanía, con propiedades diferentes en relación a la maleabilidad y resistencia. Este trabajo tuvo como objetivo aplicar la espectroscopía de infrarrojo cercano (FT-NIR) para la discriminación de cuatro especies de Salix, comparando muestras de materia maciza y partículas. Las muestras de Salix viminalis, Salix x rubens, Salix purpurea y Salix sp., fueron seleccionadas en siete sitios en la región del Valle del Río Canoas, Estado de Santa Catarina (Brasil). Los espectros de absorción se obtuvieron en FT-NIR espectrofotómetro (Bruker Tensor 37). La forma y la granulometría de las muestras de Salix spp. tienen influencia en la discriminación de las especies por FT-NIR. La técnica tuvo mayor capacidad de distinción para la granulometría de menor tamaño.<hr/>In Brazil, the cultivated species of genus Salix have great importance in crafts, with different properties in relation to malleability and resistance. This paper aimed to apply near infrared spectroscopy (FT-NIR) for discrimination of four Salix species, comparing solid sample and particulate material. Samples from Salix viminalis, Salix x rubens, Salix purpurea and Salix sp. were collected in seven sites in the region of Rio Canoas Valley, Santa Catarina State, Brazil. It was obtained absorbance spectra in FT-NIR (Bruker Tensor 37). The shape and particle size of Salix spp. influenced the discrimination of species by near infrared. The technique had a more efficient distinction for smaller particle size samples. <![CDATA[<strong>Effects of nano-clay on biological resistance of wood-plastic composite against five wood-deteriorating fungi</strong>]]> Effects of nano-clay on weight loss of wood-plastic composites (WPC) by five fungi were studied. Nanoclay particles of 20 to 50 nm size were applied at 2, 4, and 6% WPC of 0,90 g/cm³ density. The white-rot fungi Physisporinus vitreus, Pleurotus ostreatus and Trametes versicolor as well as the brown-rot species Antrodia vaillantii and Coniophora puteana were used. Mass loss tests were conducted according to the European standard. The highest (3,2%) and lowest (0,2%) mass losses were produced by T. versicolor and P. vitreus in the control and 6%-nanoclay treatments, respectively. Obviously the weight loss of WPC depends on the fungus species. Although weight losses were extremely low, nano-clay considerably inhibited the growth of wood-deteriorating fungi. Mass loss correlated with water absorption.