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Maderas. Ciencia y tecnología
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This is an Open Access Journal

Open Access journal
ISSN (Print) 0718-221X - ISSN (Online) 0717-3644
Published by SciELO

[672 journals]

Mechanical and fire properties of oriental beech impregnated with
fire-retardants and coated with polyurea/polyurethane hybrid and epoxy
resins
- Abstract: Abstract: This study was performed to investigate some mechanical properties such as modulus of rupture and compression strength parallel to grain and some fire properties such as weight loss and temperature values of Oriental beech (Fagus orientalis) treated with fire-retardants and coated with polyurethane/polyurea hybrid resin and epoxy resin were investigated. The coatings are based on epoxy and polyurethane\polyurea hybrid resins. Firstly, an impregnation method was applied by using fire-retardants which are boron chemicals and ammonium sulfate before coating process. Oriental beech was impregnated with 3 % aqueous solution of boric acid, borax, boric acid and borax mixture (1:1), and ammonium sulfate. Oriental beech was primed with epoxy resin by using Sikafloor®-156, and then coated with Sikalastic®-851, a polyurethane/polyurea hybrid resin. Results showed that modulus of rupture and compression strength parallel to grain values of polyurethane/polyurea and epoxy resin coated Oriental beech wood were higher than that of un-treated and non-coated (control) group. Fire-retardants treatment before polyurethane/polyurea and epoxy resin coatings caused to decrease modulus of rupture and compression strength parallel to grain values of Oriental beech in some extent. Weight loss and temprature values of polyurethane/polyurea and epoxy resin coated Oriental beech were higher than that of un-treated and non-coated (control) group. Hovewer, fire-retardants treatment before polyurethane/polyurea and epoxy resin coatings improved fire properties of Oriental beech wood.
Combining artificial neural network and moth-flame optimization algorithm
for optimization of ultrasound-assisted and microwave-assisted extraction
parameters: Bark of Pinus brutia
- Abstract: Abstract: In this study, the extraction parameters of Pinus brutia bark were optimized using a hybrid artificial intelligence technique. Firstly, the bark samples were extracted by ultrasound-assisted extraction and microwave-assisted extraction which are defined as ‘green’ extraction methods at different conditions. The selected extraction parameters for ultrasound-assisted extraction were 0:100; 20:80; 40:60; 80:20 (%) ethanol: water ratios; 40 ºC, 60 °C extraction temperatures and 5 min, 10 min, 15 min, 20 min extraction times and for microwave-assisted extraction were 90, 180, 360, 600, 900 (W) microwave power, 0:100; 20:80; 40:60; 60:40; 80:20 (%) ethanol: water ratios. Then Stiasny number, condensed tannin content and reducing sugar content of all extracts were determined. Next, the prediction models were developed for each studied parameter using Artificial Neural Network. Finally, the extraction parameters were optimized using Moth-Flame Optimization Algorithm. After that optimization process, while the extraction time was the same (5 min), the ethanol: water ratio and extraction temperature values differed for the optimization of all studied assays of ultrasound-assisted extraction. Also, microwave power and ethanol: water ratio variables were found in different values for each assay of microwave-assisted extraction. The results showed that the Artificial Neural Network and Moth-Flame Optimization could be a novel and powerful hybrid approach to optimize the extraction parameters of Pinus brutia barks with saving time, cost, chemical and effort.
Lumber drying of Pinus: Geostatistics applied to drying kilns
- Abstract: Abstract: This study aimed to evaluate the spatial distribution of the air circulation speed and the final moisture content of pine lumber after kiln drying by using geostatistics. Two kilns acting on boards of 27 mm and 42 mm were evaluated. Air circulation speed and final moisture content were collected in different regions of the kilns. There was no significant difference for air circulation speed and final moisture content between the front and rear regions of the equipment. In the horizontal axis (Y-axis), air circulation speed averages did not differ statistically in both situations, but higher values for this variable were obtained from the spaces between the piles. Final moisture content tended to increase when closer to the door opening. In the vertical axis (Z-axis), the lower part tended to reach higher air circulation speed values. Thus, the spatial behavior influences the air circulation speed and final moisture content during lumber drying. Besides, the variograms presented the same tendency in comparison to the data obtained in a conventional manner, which indicates that geostatistics can be used to represent variables in kilns during the drying process.
Effect of the thermal treatment on the chemical components, sorption, and
shrinkage properties of Tectona grandis juvenile wood
- Abstract: Abstract: The effect of thermal treatment on the chemical components, equilibrium moisture content (EMC), and shrinkage of teak juvenile wood was studied. Heartwood and sapwood samples were thermally-treated at 180 ºC and 200 ºC. Extractive, Klason lignin, holocellulose, and α-cellulose contents, as well as pH on untreated and thermally-treated woods, were determined. The EMC was reached at five relative humidity (RH) levels using saturated salt solutions: 86 % (KCl), 76 % (NaCl), 58 % (NaBr), 33 % (MgCl2), and 0 % (P2O5). Linear and volumetric shrinkages were calculated for all EMCs. The ratio of sorption (S), coefficient of shrinkage (h), and fiber saturation point (FSP) were also determined. Thermally-treated wood exhibited lower holocellulose and α-cellulose contents than untreated wood and increased acidity due to degradation of the hemicelluloses. The thermal treatment reduced the EMC of heartwood and sapwood. However, sapwood was more sensitive to RH variations than heartwood regardless of the treatment. Thermally-treated woods had higher hygroscopic and dimensional stabilities, and lower FSP than untreated wood. The thermal treatment did not affect radial shrinkage of the heartwood between 33 % and 86 % RH. Heartwood was more sensitive to the effect of the thermal treatment on shrinkage and degradation of cell wall polymers compared to sapwood.
Influence of growth parameters on wood density of Acacia
auriculiformis
- Abstract: Abstract: Understanding the drivers of wood density variation both within a tree and between trees is important in predicting the quality of wood logs and improving this quality through adequate forestry management. This study examined the effect of the diameter growth of Acacia auriculiformis on its wood density variation. The study was conducted in the South of Benin in four plantations of Acacia auriculiformis. Near infrared spectroscopy (NIRS) method was used to predict the basic density of 225 tree wood cores of Acacia auriculiformis. A predicting model of the average tree density using the diameter as predictor was established. The relationship between wood density and tree diameter was best described by a linear mixed-effect model. The average wood density of trees increased with the diameter. The study concluded that the quality of the species logs can be improved through regular thinning and genetic selection.
Evaluation and comparison of control and heat treated L-shape furniture
joints produced from Scotch pine and ash wood under static bending and
cyclic fatigue bending loadings
- Abstract: Abstract: This study investigated how the mechanical properties of L-shape joints produced from heat treated Scotch pine or ash wood behaved under cyclic fatigue loading and compared this with the mechanical properties of non-heat treated wood materials. Additionally, static bending performances of the L-shape of joints were investigated and compared to fatigue bending performance of same type of joints. Results indicated that increasing number of staple from 6 to 8 and density generally increased static bending of L-shape joints. Static bending resistance of L-shape joints produced from control Ash wood significantly higher than those of L-shape joints produced from heat treated Ash wood while no significant difference were observed between static bending resistance L-shape joints produced from control Scotch pine and L-shape joints produced from heat treated Scotch pine wood. The fatigue bending resistances of L-shape joints produced from heat treated samples generally passed and failed the same loading steps with those produced from control samples which means both L-shape joints could be used in same service area. L-shape joints under static and fatigue loadings mostly indicated staple leg shear mode. The one under fatigue loading was more than the one under static loading. Additionally, some joints under fatigue loading indicated staple rupture. The overall ratio of static bending loading to cyclic fatigue bending loading for L-shape joints was obtained as 2.85.
Application of a strain gauge to assess drying stresses in normal and
tension wood of Corymbia citriodora
- Abstract: Abstract: The quantitative evaluation of longitudinal drying strain can provide relevant information for the processing wood and lumber industry, especially with regard to reaction wood in Corymbia, since little has been published. The objective of this work was to evaluate the effect of the steam conditioning and the cooling on the longitudinal drying strain (LDS) obtained from a strain gauge, called extensometer, in boards of both normal and tension wood of Corymbia citriodora. Lumbers 30 mm thick were produced and kiln dried at the initial temperature of 40°C, final temperature of 65°C and drying potential of 2,1. The LDS were measured before and after steam conditioning on hot and cold lumbers. It was observed that the conditioning did not reduce the LDS. Hot lumbers showed higher LDS values than the cold lumbers. The LDS values measured in normal, tension and opposite woods were statistically similar, indicating that the type of wood was not an influential factor in the appearance of longitudinal drying stresses. Extensometer proved to be feasible for measuring LDS, allowing its easy and quick quantification.
Changes in the content and composition of the extractives in thermally
modified tropical hardwoods
- Abstract: Abstract: Chemical composition of wood is known to change during thermal treatments. Two species grown in Turkey, afrormosia (Pericopsis elata) and duka (Tapirira guianensis) were heat treated according to Thermowood® method. Lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol and water were determined. Wood extracts were analysed by gas chromatography with mass detection and existing compounds were identified by NIST17 database. Results show that hemicelluloses and cellulose content decreased for both heat-treated woods along the treatment while lignin percentage increased. The analysis of extractives has shown several compounds normally associated to lignin thermal degradation that increased along the treatment. At the same time several compounds associated to carbohydrate thermal degradation were found in all the extracts for both heat-treated woods. These founding have allowed the understanding of the degradation pattern of wood during thermal modification. There was not much difference between afrormosia and duka woods structural compounds behaviour along thermal modification. However, the variation of the amount of extractives along the treatment depended on the species.
Applying colorimetry for wood differentiation of fabaceae species grown in
southern Brazil
- Abstract: Abstract: Because of the need for identification of forest species, especially for detection of illegal wood trade, the objective of this study was to evaluate the potential of colorimetry for differentiation of Inga vera Willd., Muellera campestris (Mart. ex Benth.) M.J. Silva & A.M.G. Azevedo and Machaerium paraguariense Hassl., species of the Fabaceae family, native to the Araucaria Forest in the state of Santa Catarina, southern Brazil. Discs at breast height were collected from three trees of each species and the colorimetric parameters (L*, a*, b*, C* and h) and visible spectra were evaluated in different radial position of the trunk (near bark, intermediate and near pith) and three different anatomical sections (transversal, radial and tangential surfaces). Mean values of hue angle (h) among the colorimetric parameters resulted in the highest potential for species discrimination. With respect to radial trunk position and anatomical section, parameters a* (green-red) and h were not statistically different, independent of the wood samples evaluated. For other parameters (L*, b* and C*), each species presented distinct results. Principal component analysis with second derivative of visible spectra discriminated all species. Colorimetry associated with chemometrics allowed to distinguish I. vera, M. campestris and M. paraguariense.
Comparative study on weathering durability property of phenol formaldehyde
resin modified sweetgum and southern pine specimens
- Abstract: Abstract: The effects of low molecular weight phenol formaldehyde resin on weathering durability property of sweetgum (Liquidambar styraciflua) and southern pine (Pinus taeda) specimens were studied using six wet-dry cycles with ultraviolet light accelerated weathering test following ASTM via evaluating the water repellent efficiency, dimensional stability, and crack formation of wood. The results showed that 1) the water repellent efficiency of treated quarter-sawn sweetgum specimens was higher than those of treated quarter-sawn and flat-sawn southern pine specimens; 2) the dimensional stabilities of sweetgum and southern pine specimens were all improved by impregnating low molecular weight phenol formaldehyde resin, especially for sweetgum; 3) there were clearly more cracks on exposed ends and surfaces of all treated sweetgum and southern pine specimens than those on control ones, indicating that the low molecular weight phenol formaldehyde resin modification used in this study were not able to improve the anti-cracking properties of sweetgum and southern pine specimens. Generally, the sweetgum was more suitable to be impregnated with low molecular weight phenol formaldehyde resin than southern pine with the procedure described according to dimensional stability and water repellent efficiency, in order to improve the weathering durability.
Particle image velocimetry technique and ultrasound method to obtain the
modulus of elasticity of Bertholletia excelsa wood
- Abstract: Abstract: Non-destructive techniques for characterizing materials in-service have been increasing in importance. Thus, it is relevant to assess the potential of non-destructive techniques for solid materials. This work aimed to determine the modulus of elasticity of Bertholletia excelsa wood using the particle image velocimetry technique and the ultrasound method to compare the results with the conventional methodology. For this purpose, samples of Bertholletia excelsa were made using a circular saw. The samples were evaluated for sound propagation to calculate the modulus of elasticity using ultrasound equipment. Subsequently, they were subjected to the compression parallel to grain test in a universal testing machine. The samples were marked and monitored during the loading session, with the repeated capture of images using a professional camera. The deformation values obtained were used to estimate the modulus of elasticity using the particle image velocimetry technique. The mean values of modulus of elasticity found were 17403 MPa for ultrasound, 15589 MPa for the particle image velocimetry technique, and 15333 MPa for the universal testing machine. The particle image velocimetry technique was considered to be statistically similar (Tukey α = 0,05) to the other methods tested. The linear coefficient of determination (R2) between the particle image velocimetry technique and the universal testing machine was 0,95, a high and satisfactory value. Thus, the particle image velocimetry technique and the ultrasound method are valid to estimate the modulus of elasticity of Bertholletia excelsa wood and possibly of woods with similar technological characteristics.
Mechanical, thermal, and morphological behaviour studies on coconut shell
and palm kernel filler biocomposite
- Abstract: Abstract: In the present work, the composite materials were prepared from coconut shell powder, palm kernel powder, and epoxy resin. The addition of coconut shell powder was considered when preparing the composite samples, and mechanical properties such as tensile strength, hardness, impact, bending strength, physical behavior water absorption, as well as morphological tests, were conducted using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope, and Thermogravimetric Analysis for both the prepared composite material boards and chipboard. The minimal variation of tensile stress and percentage of elongation between the 50 % coconut shell powder composite material and the wooden chipboard material is 4,44 MPa and 1,00 %, respectively, according to the findings of experimental tests.The lowest compressive stress and hardness variations between coconut shell powder composite material and wooden chipboard are found to be 0,14 MPa and 3,2 MPa, respectively. It is determined that the composite materials made from waste shell powders and epoxy resin are suitable for applications such as panel boards, automotive interior dashboards, roof sheets, and doors.
Effectiveness of European oak wood staining with iron (II) sulphate during
natural weathering
- Abstract: Abstract: Artificial graying of wood can be solution for contemporary trends of using uncoated wood for the arrangement of external architecture. The presented work was aimed at investigation of colour changes of European oak (Quercus sp.) wood surface treated with iron (II) sulphate. Three different procedures differing in time (2 h and 24 h) and temperature (20 °C and 70 °C) were used, as well as three different concentrations of aqueous iron (II) sulphate solutions (10 %, 20 %, 30 %). Beside the colour itself, it was evaluated the stained oak wood discolouration due to natural weathering. Thanks to iron (II) sulphate, wood colour changed to dark grey. In general, the colour changes on tangential section of wood were higher than those on radial section what was result of wood structure, in particular parenchyma cells arrangement in wooden rays. Contrary to expectations, the concentration of the iron (II) sulphate solution was not of significant importance for wood staining. Usage of concentrations higher than 10 % for the modification of the colour of wood gives the same effects. However, with increasing solution used to wood staining, the colour stability of the wood decreases during external exposure. The parameters of the procedure were not significantly affected. This allows the application of the simplest and least time-consuming modification method to be considered.
Environmental impact assessment of timber houses: “La casa
Uruguaya” case study
- Abstract: Resumen: Varias medidas se están llevando a cabo en Uruguay para reducir las emisiones de CO2 a la atmósfera, entre las que destaca la modificación de la matriz energética. En estos últimos años más del 90% de la energía eléctrica que se produjo provino de fuentes renovables, tales como la eólica, la hidroenergía o la biomasa. A pesar de estos progresos, el sector de la edificación, la construcción y el transporte continúan siendo en gran parte responsables de los impactos ambientales que producen las actividades humanas en el país. Por otra parte, diversos estudios muestran el avance en el desarrollo de metodologías de cálculo y la definición de estrategias que permitan reducirlas. En ese sentido la metodología del Análisis del Ciclo de Vida (ACV) es considerada una de las más trasparentes y reconocidas por la comunidad científica internacional. Este estudio tiene por objetivo el desarrollo de una propuesta metodológica basada en el ACV, para calcular los impactos ambientales que producen los edificios residenciales en madera durante su ciclo de vida. La verificación experimental se desarrolla a través del caso de “La Casa Uruguaya”, una vivienda social unifamiliar construida en madera. La metodología propuesta permite, a partir de la fase avanzada del diseño de la vivienda, obtener resultados de los impactos ambientales que se producen durante su ciclo de vida completo. Los resultados demuestran la relevancia de las etapas de uso (uso de energía, mantenimiento, reparación, rehabilitación y sustitución) y de producto (extracción de materias primas, fabricación y transporte) sobre el resto de las fases del ciclo de vida consideradas.Abstract: Several actions have been taken in Uruguay to reduce CO2 atmospheric emissions, including modification of the energy matrix. In recent years more than 90% of electricity was produced by renewable sources, such as wind power, hydro (run-of-river) or biomass. Despite this fact, the building, construction, and transport sectors are still great responsible of the environmental impacts produced by human activities. Moreover, several studies show advances of methodologies that allow the environmental impact calculation and the definition strategies for reduction. Life Cycle Assessment (LCA) is considered one of the most transparent and recognized method by the international scientific community. This study aims to develop a methodology based on LCA, to calculate the environmental impacts produced by timber buildings during their life cycle. The case study verification focuses on “La Casa Uruguaya”, a social single-family timber house. The proposed methodology allows obtaining the environmental impacts of the whole life cycle, from the detailed design stages of design. Results show the relevance of the use stage (energy consumption, maintenance, repair, refurbishment and replacement) and product stage (raw material, manufacture and transport) compared to the rest of the life cycle stages included in the study.
An evaluation of clove (Eugenia caryophyllata) essential oil as a
potential alternative antifungal wood protection system for cultural
heritage conservation
- Abstract: Abstract: This paper investigates the potential of clove (Eugenia caryophyllata) essential oil (C-EO) as a wood protection system for use in cultural heritage conservation. The preventive and curative antifungal efficacy of C-EO was compared to a boron containing wood preservative (Diffusit S) in two laboratory tests on European beech (Fagus sylvatica) and Scots pine sapwood (Pinus sylvestris) mini-blocks. Non-sterile, air-infected wood samples were employed in the first test, while wood samples with active attack, as result of inoculation with three fungal strains isolated from cultural heritage sites, in the second test. Untreated controls and C-EO-treated wood blocks were incubated up to 150 days to monitor and quantify fungal growth. The experimental results showed antifungal efficacy of C-EO to be higher than that of the boron wood preservative at the concentrations used. Concentrations of C-EO 5 % - 10 % in ethyl alcohol prevented mould growth for at least 150 days, while a concentration of 10 % delayed or suppressed active attack by decay fungi. This effect, determined up to 90 days of incubation, was dependant on the type of fungus.
Preparation of plywood panels using waste milk pouches as an adhesive
- Abstract: Abstract: Recycling of single use plastic like milk pouches, oil pouches, etc. for high value products can have significant environmental, social and economic implications. The present study focuses on the utilization of waste milk pouches made out of low-density polyethylene as the bonding agent in preparation of plywood panels. Plywood panels with varying content of polymeric content (milk pouch layers) were prepared and evaluated for physical and mechanical properties. The results indicated that with increase in the dosage of milk-pouch content, both physical as well as mechanical properties of the plywood improved substantially. There was nearly three folds difference in modulus of rupture of panel prepared with 80 g/m2 and 310 g/m2 polymer content. Similarly, tensile strength, modulus of elasticity also increased significantly with increase in polymer content. The glue shear strength, which is very important for plywood, was found to be influenced by the quantity of polymer. Glue shear strength for panel with 80 g/m2 polymer was 0,75 MPa which increased to 1,90 MPa in panel with 310 g/m2 polymer content. It was observed that for strong bonding it is essential that the quantity of polymer should be sufficient enough to penetrate into the pores of wood creating a mechanical interlocking of veneers. The study opens up the scope of recycling of waste milk pouches in the preparation of formaldehyde free plywood.
Some surface characteristics of oriental beech wood impregnated with some
fire-retardants and coated wıth polyurea/polyurethane hybrid and epoxy
resins
- Abstract: Abstract: This study was made to determine surface characteristics such as colour, gloss, and surface hardness changes of Oriental beech (Fagus orientalis). The wood specimens were firstly impregnated with some fire-retardants (FRs) and primed with epoxy resin (EPR) and then coated with polyurethane/polyurea hybrid resin (PUU). Oriental beech was impregnated with 3 % aqueous solution of boric acid (BA), borax (BX), boric acid and borax mixture (1:1), and ammonium sulphate (AS). While Sikafloor®-156 was used for epoxy coating (EPR), Sikalastic®-851 R was used for polyurethane/polyurea hybrid coating (PUU). According to our results, all treatment groups gave negative lightness stability values after accelerated weathering. The colour stability of epoxy resin coated Oriental beech was higher than that of polyurethane/polyurea hybrid resin coated Oriental beech. Except for boric acid impregnated and polyurethane/polyurea hybrid resin coated Oriental beech, all fire-retardants treatment before polyurethane/polyurea hybrid resin and epoxy resin coatings decreased the gloss losses of Oriental beech after accelerated weathering. Fire-retardants impregnation before epoxy resin and polyurethane/polyurea hybrid resin coatings improved the surface hardness values of Oriental beech after accelerated weathering.
Physical properties of palmyra palm wood for sustainable utilization as a
structural material
- Abstract: Abstract: Physical properties are major characteristics that validate biomaterials' adaptability to commercial utilization. The moisture content, density, swelling, and shrinkage within male and female Borassus aethiopum were assessed. Green and dry moisture content, and density were tested with the oven-dry method while swelling and shrinkage were evaluated using the water-saturation test and oven-dry methods respectively. Unlike moisture content, density decreased towards the crowns and radially from the peripheries to their cores. Directional swelling decreased as: Radial > Tangential > Longitudinal. Volumetric swelling was greatest at the core of the base (6,99 %) but at least at the periphery within the middle of the male (2,89 %). However, the female recorded much swelling at the core of its mid-portion (6,23 %) and least (4,01 %) at the crown periphery. Directional shrinkage decreased identically as the male variety while the volumetric shrinkage for both varieties was not consistent. The peripheries had less moisture content, better dimensional stability and density (which influences wood strength) at the butt than those of the core indicating the peripheries would maintain its original dimension and strength when subjected to environmental changes and be more viable for structural works than the core.
Physical, chemical and mechanical characterization of Acrocarpus
fraxinifolius cultivated in Sao Paulo
- Abstract: Abstract: Indian cedar (Acrocarpus fraxinifolius) is a wood species that occurs naturally in India, Myanmar (Burma) and Bangladesh, and has a high commercial value, with characteristics like mahogany and native cedars. The planting of Indian cedar has been undertaken in Brazil, but there is little information available regarding the characterization of the species. Therefore, considering its timber potential and its possibility of development in the country, the present work aimed to evaluate the physical, chemical, and mechanical properties of 9-year-old Indian cedar wood, planted in the southern region of Brazil. A low specific mass (502 kg/m³), low average dimensional stability (anisotropy coefficient of 2,09 %) was observed, in addition to the low content of extractives (1,94 %). From the mechanical characterization, an average value for the elastic modulus of 8963 MPa was obtained, and for the compressive strength parallel to the grain the average and characteristic values were 32,14 MPa and 21,46 MPa, respectively. This indicates that this wood belongs to resistance class C20 (dicotyledons). The results obtained classify the wood for use in light, external, or internal civil construction.
Optimization of CNC operating parameters to minimize surface roughness of
Pinus sylvestris using integrated artificial neural network and genetic
algorithm
- Abstract: Abstract: The surface roughness of wood is affected by the processing conditions and the material structure. So, optimization of operation parameters is very crucial to have minimum surface roughness. In this study, modeling and optimization of surface roughness (Ra) of Scotch pine (Pinus sylvestris) was investigated. Firstly, the samples were cut under different conditions 8 mm, 9 mm and 11mm depth of cut and 12 mm, 14 mm and 16 mm axial depth of cut) in computer numerical control (CNC) machine, and then surface roughness (Ra) values of samples were calculated. Then a prediction model of surface roughness was developed using artificial neural networks (ANN). Optimization process was carried out to reach minimum surface roughness of wood samples by the genetic algorithm (GA) method. MAPE value of the ANN model was found lower than 4,0 %. The optimum CNC operation parameters were 1874,5 rad/s, 3,0 m/min feed rate, 9,7 mm depth of cut and 12 mm for axial depth of cut for minimum surface roughness. As a result of study, surface roughness of Scotch pine wood can be modeled and optimized using integrated ANN and GA methods by saving time and cost.
Mass transfer properties of Acacia mangium plantation wood
- Abstract: Abstract: This study investigated the mass transfer properties (permeability and mass diffusivity) in the longitudinal, radial and tangential directions of plantation-grown Acacia mangium in VinhPhuc province,northeast, Vietnam. These properties will be used to complement a conventional drying model in the future. Measurements of gas and liquid permeability were performed using a Porometer (POROLUXTM1000). Mass diffusivity was determined in a constant humidity and temperature chamber using PVC-CHA vaporimeters. Results showed the gas permeability was significant higher than liquid with the descending order of longitudinal, radial, and tangential directions. The permeability anisotropy ratios from the longitudinal to transverse directions of Acacia mangium were much lower than other published species. However, the obvious anisotropy ratios from radial to tangential for both permeability and diffusivity, is one of concerns as they can exacerbate defects during drying. Besides, the high permeability and diffusivity of Acaciamangium compared to some other species reported compounds its relatively fast drying rate.
Plywoods of northeast Argentinian woods and soybean protein-based
adhesives: Relationship between morphological aspects of veneers and shear
strength values
- Abstract: Abstract: Three-ply plywoods were produced using pine and Eucalyptus northeast Argentinian woods. A no-added formaldehyde biobased-adhesive was used for assembly, based on chemically modified soy protein concentrate. In this work we focused on the relationship between bonding quality parameters of the plywoods and the morphology of the glued line. Wood characteristics such as contact angle, roughness, density and moisture content were measured prior to plywood assembly. Bonding quality parameters (percentage of wood failure and shear strength) of the plywood were measured according to Argentinean standard and the results were evaluated with respect to microscopic observations of the glue joint. Eucalyptus wood was suitable for plywood interior condition applications, while pine barely exceeded the standards imposed by the norm.
A novel method for producing a glulam from the wood of peeler cores
- Abstract: Abstract: This study presents an opportunity for rational utilization of poplar wood peeler cores in the production of glued laminated timber (glulam) beams. An approach for optimal use of small-diameter raw material with a circular cross-section is also proposed in order to obtain a final product in a significantly high quantitative yield. The applied novel method of sawing the peeler cores and subsequent combination of gluing the obtained lamellas allows to achieve: reduction of labor and energy consumption in the processing; rational utilization of this waste raw material; obtaining a product sought by consumers; opportunity to implement technology for the production of glulam from peeler cores. The results showed that sawing the peeler cores and obtaining lamellas with a trapezoidal cross-section leads to a high quantitative yield of 76,3 %. The final quantitative yield in subsequent technological operations in the manufacturing of engineered wood of glulam type reaches 48,8 % of the volume of raw material. In addition, equations have been working are used for the determination of the most suitable sizes of the lamellas, depending on the diameter and the kerf width.
Simultaneous treatment with oil heat and densification on physical
properties of Populus × Canadensis wood
- Abstract: Abstract: Samples of wood from Populus × canadensis (9,5 % moisture) were treated with olive oil at 195 °C simultaneously with 15 % or 30 % compression densification, and the results were compared with samples subjected to oil heat treatment without densification, and control samples. The density of the treated samples increased by 18 %, 43 % and 1,5 % respectively, and barely changed over the six subsequent months stored inside the laboratory room (at approximately 65 % RH, 20 °C). This was due to the fact that the slight weight increment caused by the additional moisture content was offset by the increase in volume from the springback effect. When subjected to atmospheres with different relative humidities, the treated samples stabilised at the same time as the control samples, although the treated samples had a significantly lower moisture absorption than the control samples. It was also observed that the hygroscopic shrinkage in oil heat densification treatment samples was approximately half those of the control samples. The initial densification was partially lost as a result of springback: approximately 3 % in the first springback at a relative humidity of 65 % RH, and an additional 4 % in the second springback to a relative humidity of 85 % RH. Once this latter relative humidity had been attained, no new losses in densification were observed. The ageing of the oil used in the treatment caused a slight loss of densification in the densest samples.
Fumigation of imported Tectona grandis and southern yellow pine with
Pongamia pinnata seed oil against sapstain and mould
- Abstract: Abstract: An eco-friendly alternative of Pongamia pinnata seed oil was tested for fumigation of imported Tectona grandis and Pinus spp. (Southern yellow pine) against sap stain and mould fungi at 25°C± 2°C and 75 % ± 5 % relative humidity. Veneeer and block samples of both species, and Petri dishes with agar media were fumigated with three different concentrations (w/v) of Pongamia pinnata seed oil and exhibited significant inhibition of fungal growth in comparison to the control sets, with the highest concentration of 6,4 g/ 8 mL3 proving to be the most lethal. Tectona grandis exhibited no infestation of sapstain and mould in either type of specimens whereas highly perishable Southern yellow pine displayed slight infestation of 4 % and 5 % with 1,6 g/ 2 mL3 of Pongamia pinnata seed oil for venner and block specimens as compared to 18 % and 20 % infestation observed in respective controls. The infestation on Southern yellow pine reduced to 1 % and 2 % respectively for veneers and blocks with 4 g/ 5 mL3 of Pongamia pinnata seed oil and was completely inhibited at 6,4 g/ 8 mL3 for both type of Southern yellow pine specimens. Petri plates returned similar findings where all higher concentrations inhibited mould growth completely and the lowest concentration exhibited meagre mould growth. Sapstain was inhibited successfully by all three concentrations of Pongamia pinnata seed oil on agar media.