Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Dado el impacto que tiene en la productividad y en la reducción de costos, la toma de decisiones es uno de los aspectos más requeridos en la industria. En la fabricación de tableros, la calidad del producto es función de múltiples variables, especialmente de la variabilidad de la madera. Esta calidad depende, entre otros factores, de la adherencia entre chapas o resistencia a la tracción perpendicular. El objetivo principal de este estudio fue evaluar un enfoque de Machine Learning, esto es modelos de aprendizaje automático, que permitan predecir la adherencia bajo condiciones de operación industrial, en la etapa de encolado y pre-prensado. Las principales variables de control que determinan esta adherencia son los tiempos operacionales, la cantidad de adhesivo, las condiciones ambientales y la temperatura en la chapa.  Usando la metodología de analítica de datos Knowledge Discovery in Databases, se evaluaron algoritmos de Redes Neuronales Artificiales  y Máquina de Soporte Vectorial. Se obtuvieron buenos resultados al usar las funciones Relu y Sigmoid. La función Sigmoid entregó mejores resultados de acierto global (accuracy sobre el 66 %) y precisión en encontrar resultados correctos (casi 70 %). Al usar la función Relu se obtuvó un mejor recall (sobre el 74 %), lo que muestra su buena aptitud para identificar la realidad. Estos resultados muestran la viabilidad de usar inteligencia artificial en la predicción de procesos complejos. Muchos espacios de mejora se abren con un adecuado pretratamiento de las variables de proceso a objeto de obtener mejores resultados. El aporte de este trabajo radica en la definición de una metodología a ser usada en plantas industriales, en particular en la fabricación de tableros contrachapados, y en mostrar la factibilidad del uso de datos industriales y Machine Learning en la predicción de la calidad del producto.

The use of wood as a bioenergetic source requires knowledge of its technical properties. The rubber tree Hevea brasiliensis has an economic life cycle of 25 to 30 years in Brazil. It is used for extracting rubber and generating residual wood for fuel. Our goal was to characterize the wood quality of 10 clonal progenies as a source of raw material for bioenergy. Ten clonal progenies of 12-year-old Hevea brasiliensis from an experimental planting in Selvíria municipality were evaluated. Three trees per clone were evaluated for individual properties of Higher Heating Value, immediate chemical analysis, chemical composition, fiber dimensions, thermogravimetric analysis of wood under nitrogen atmosphere and Fourier Transform Infrared Spectrosocopy analysis. We highlight clone IAC 311 for fuel because it presents elevated Higher Heating Value and fixed carbon and less volatile material. However, the other genetic materials studied also meet the specifications for energy use and can be highly viable given their physical, chemical, energy, and thermal properties.

In this study, the purpose was to improve outdoor performance of cement bonded wood composite due to their biodegradation and sensitivity to moisture especially in warm and humid climates. Cement bonded wood composites were treated with different concentrations (10 %, 25 %, 50 %, 75 % and 100 %) of water repellent. Water repellent used was an organo-silicon based, nano-sized, eco-friendly, water-based agents. Dipping and pressure systems were applied for composite treatment. Water absorption, thickness swelling, accelerated weathering, color changes and mechanical properties after accelerated weathering were determined for treated and untreated cement-bonded composites. Results showed that treatment of composites with water repellent provided a transparent layer on composite surface. Thus, lower water absorption and thickness swelling results in the beginning of immersion in water. Treated and untreated composites were exposed to an accelerated weathering test for 350 h. Their mechanical strength including modulus of rupture, modulus of elasticity and internal bonding properties were decreased after 350 h of weathering. However, overall results after weathering test showed that all panels’ mechanical properties provided minimum modulus of rupture, modulus of elasticity and internal bonding requirements of the EN standards.

The aim of this study was to determine the usability of selected natural dye extracts as environmentally friendly colorants that are used in painting of MDF based furniture and evaluate their resistance to scratch resistance, adhesion resistance, and surface hardness properties. In this study, the water-based lacquer coatings were prepared with natural dyes obtained from purple cabbage (Brassica oleracea), safflower (Carthamus tinctorius L.), Red beetroot (Beta vulgaris L.) and three synthetic paints that were black, blue and light blue as a comparison. Coated MDF test panels used for evaluation of performances of dyes to abiotic factors that are determined by mechanical tests such as scratch resistance, adhesion resistance, and surface hardness. As a result of the study, it has been observed that, except for scratch resistance, natural dyes perform as well as synthetic ones as alternative colorants in the lacquer coatings. Thus, natural and aesthetic raw materials that are environmentally friendly dyes can be used safely especially in children's furniture and for wood-based products that are especially used indoors.

Radiata pine boards were coated with two different methods A and B both beginning with a hydro primer and finishing with a mat oil but method A using an acrylic high gloss coating and method B three layers of an acrylic sealer in between. The samples were subjected to aging processes for 144 h, 288 h, and 432 h by using UV-A 340 nm lamps. The CIE L*a*b* and CIE L*C*H* coordinates were determined (L*, a*, b*, C*, ho*, ΔE*), gloss (perpendicular (⊥) and parallel (//) to the grain at 20°, 60°, and 85° angles) and surface adhesion strength via the pull-off method were tested before and after weathering.  Results have shown that lightness (L*), decreases with weathering for both varnish applications with a higher decrease for the B coating system. Redness increased for both applications with no significant differences. At the same time there was a yellowing of the samples along the weathering period. Parallel and perpendicular gloss decreased for 20º and 60º angles while it increased for 85º angle. The adhesion strength of method A was higher and its decrease with weathering was smaller than for method B. Both varnish applications have proven to confer some protection against wood discoloration, but method A showed the best results and is therefore the best method to be used by radiata pine.

In recent years, laser material processing technology has become quite widespread. The quality of laser processing of wood materials is very important in terms of not causing secondary processes in the production process. In this study, computerized numerical control laser cutting qualities of some wood species that are frequently used in industrial product manufacturing were investigated. In the study, 80 % irradiation and 10 mm/sec laser cutting speed were applied to the test samples in a computerized numerical control laser machine with a 130 W carbon dioxide gas cylinder. In the case of laser cutting of 5 different wood species in the direction vertical to and parallel to the fibers, the average of the upper and lower kerf width, the difference in the width of the upper and lower kerf, the average of the width of the heat-affected zone, the width of the heat-affected zone were evaluated. In line with the findings, the effects of wood species differences on laser cutting quality in terms of material consumption, precision machining, and smoothness of cutting geometry were investigated. As a result, the highest quality cutting values ​​were obtained from the laser cutting of the bamboo massif in terms of wood species, in the direction vertical to the fibers of the wood materials.

Enzymatic hydrolysis is an environmentally friendly technology to produce sugars from pretreated biomass. Here, we show that the new Il-11 Irpex lacteus strain can synthesize cellulases in a high quantity. The peptone and filter paper contained in the medium significantly enhanced activity of endo-1,4-β-D-glucanases (app. 50 IU/mL) and total cellulases (app. 9 IU/mL), whereas the medium with peptone and sodium carboxymethyl cellulose stimulated activity of exo-1,4-β-D-glucanases (33 IU/mL). The expression of cellulases reached its maximum within 96–144 hours, and the optimum pH is 3,7. Thermal treatment at 30 °C for 60 minutes activated endo-1,4-β-D-glucanases and total cellulases, while exo-1,4-β-D-glucanases activity was enhanced following 40 °C treatment. In total, the cellulases complex (300 IU/g) saccharified untreated cellulose by 38 % in 48 hours. Concentrate with filter paper activity 100 IU/g is the more balanced enzyme-substrate ratio (2 %), which allows prolonging the saccharification process that will have a positive effect on the cost of the final product.

Particleboard can be produced from a mixture of different lignocellulosic materials, which can be chosen depending on the density required for the panel and its applications. The aim of this study was to evaluate the mechanical properties of particleboard with bamboo, pine and mate for a new product of high density for the special applications currently served by HDF. Particles of bamboo (Phyllostachys aurea) finely chopped sticks of mate (Ilex paraguariensis) and commercial particles of southern pine (Pinus taeda) wood were used. These particles used 100 % by weight in the panel or in mixtures of 50 % each (three mixtures) or in a triple mixture of one third each, were glued in a drum-type rotary mixer with melamine-urea-formaldehyde (MUF) resin, and pressed in hydraulic press at 120 °C and 5,88 MPa for 10 minutes, up to 6 mm thickness. The panels were produced with 0,90 g∙cm-3 nominal density and, after pressing, were conditioned at 20 ºC and 65 % relative humidity. Statistical was performed by means the variance analysis and simplex centroid experimental design, with three replicates. It was found the use of pine particles contributed mainly to increase the panel's strength and stiffness, while the use of mate particles facilitated internal bond strength. The results compared with the ANSI A208.1 indicate that the panels with potential for use as floors and other applications requiring medium to high mechanical strength. The mixtures modeling showed that the water absorption, the strength and stiffness in bending and the internal bond strength are explained by the cubic model, while the thickness swelling and hardness are explained by the quadratic model. The best physical and mechanical properties results were found for the pine, bamboo and mate same ratio mixture.

Cryptomeria fortunei has been widely planted in many cities in southern China. Eventually some of this material may be utilized for timber, but there are relatively few studies of durability of this resource.   There is also some question as to whether Cryptomeria fortunei is a synonym for Cryptomeria japonica or Japanese cedar (Sugi). Evaluating the durability of the Chinese resource will help ensure that the decay resistance of this urban plantation resource is properly categorized. The decay resistance of Cryptomeria fortunei wood was assessed in soil block and agar block tests against Trametes versicolor, Gloeophyllum trabeum and Rhodonia placenta. Hot water and ethanol extractive contents of the heartwood were determined on sections from various distances above ground and then FTIR spectroscopy was used to characterize the wood before and after fungal exposure. Weight losses in sapwood were consistent with the minimal decay resistance of this portion of the wood. Inner and outer heartwood weight losses were more variable suggesting that the heartwood of this species would be considered to be only moderately durable.  Extractives were weakly correlated with decay resistance. FTIR results were more variable, although they suggested heavier attack of lignin components by the brown rot fungi. The results suggest that Cryptomeria fortunei would need to be protected from the weather unless supplemental preservative treatments were applied.

Based on most recently published studies, there is a large variability in both the mechanical properties of wood and sample sizes selected to evaluate them. This study aims to define sampling sufficiency for some mechanical properties of wood, which were bending strength, bending modulus, compressive strength, compressive modulus, hardness, and shear strength. The mechanical tests were carried out according to the ASTM D143 on wood samples cut from clonal Eucalyptus planted in southern Brazil. Sampling sufficiency was determined by an intensive computational method based on resampling of original data using Monte Carlo simulations. The experimental tests data conformed to the normal distribution and most of the obtained sufficient sample sizes determined by Monte Carlo simulation were above those sample sizes used in most already published studies. Furthermore, properties related to wood stiffness presented smaller variabilities than their respective properties associated with wood strength, leading to smaller sample sizes for the former cases.