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

This study aimed to synthesize titanium dioxide nanoparticles by microwave-assisted hydrothermal method to incorporate them to the structure of Pinus elliottii wood. The color changes and the decay resistance of impregnated wood was investigated. The titanium dioxide nanoparticles were impregnated into Pinus elliottii wood by vacuum-pressure and simple immersion methods. Furthermore, Pinus elliottii wood was treated with chromated copper borate solution tocompare their effectiveness to the titanium dioxide treated wood. The titanium dioxide nanoparticles impregnated by vacuum-pressure were presented especially on the wood surface, forming a homogeneous coating. The titanium dioxide nanoparticles did not change the natural color of wood and, at the same time, decreased the degree of the white rot fungus (Ganoderma applanatum) colonization in the wood structure and the wood decay, compared to the untreated one. The titanium dioxide treated wood samples provided similar protection against decay in comparison to wood treated with chromated copper borate. The impegnation with titanium dioxide nanoparticles can be a good alternative to decrease/avoid the fungi proliferation, providing to Pinus elliottii wood a self-cleaning mechanism.   PDF XML

The efficacy of monoethanolamine and sodium bisulfite pulping black liquors at three concentrations of 1; 1,5 and 2% on the preservation of poplar wood from white rot (Trametes versicolor) was investigated. The wood specimens were impregnated with the black liquors using a full-cell method. The black liquors enhanced the decay resistance without any reduction in mechanical strength, and a remarkable increase was observed at higher concentrations and weight gain percentage. The performance of monoethanolamine black liquor was more pronounced, probably due to lower kappa number and higher pH. The durability class of specimens impregnated with 2% monoethanolamine and sodium bisulfite black liquors improved from 5 (not durable) to 1 (very durable), and from 5 to 3 (moderately durable), respectively. Chemical analysis showed that the presence of additional lignin in wood alters the white rot. Results of anatomical studies showed that the fibers of the control and impregnated wood specimens were collapsed after 16 weeks of incubation. Leaching tests confirmed that the fixation of black liquors in wood should be examined for further studies.   PDF XML

The feasibility of using rattan canes (Laccosperma secundiflorum and Eremospatha macrocarpa) as reinforced fillers for high density polyethylene based plastic composite production was investigated. Extruded composites were tested for water sorption, tensile and thermal properties. The results obtained indicated that the rattan composites were dimensionally (water absorption: 2,2-21,4% thickness swell: 0,9-5,3%) and thermally stable (Tc: 116,8-118,2°C) and possessed adequate tensile properties (7,3-21,7 MPa). Composites made from L. secundiflorum had higher strength and thermal properties but lower sorption values compared to those of E. macrocarpa. Differences in the densities of the composites and the anatomical structures of the rattans seemed to influence properties of the composites.   PDF XML

The aim of this study was to investigate micro-mechanical properties of Oak (Quercus petraea) wood and to compare with standard-size test specimens values. Bending strength, modulus of elasticity in bending, compression strength and tensile strength were determined using micro- and standard-size mechanical test samples. In the micro- and standard size samples, bending strengths were evaluated as 71,2 MPa and 99,4 MPa, modulus of elasticity in bending as 2741,3 MPa and 11394,1 MPa tensile strengths as 98,7 MPa and 93,8 MPa and compression strengths as 45,4 MPa and 46,6 MPa respectively.The results showed that the bending strength, modulus of elasticity and compression strength of the micro-size samples were lower compared to the standard-size samples, while the tensile strength was higher in the micro-size samples. The compression strength values of micro- and standard-size samples were not significantly different. The regression analyses indicated a positive linear regression between the mechanical properties of micro- and standard-size samples. Micro-size specimens can be used to estimate the mechanical properties of Oak wood when obtaining standard-size specimens is not possible.   PDF XML

The Scientific-Editor and Technical-Editor of Maderas-Cienc Tecnol are grateful to the reviewers for their assistance as referees into the peer review processes of the journal.The quality of the scientific contents of the Maderas-Cienc Tecnol depends on the conscientious work of the reviewers. We appreciate their effort in reviewing the manuscripts and greatly value their availibility for sharing their time and expertise with Maderas-Cienc Tecnol journal. We appreciate their careful evaluation of the manuscripts received during 2016-2017 period, to the next list of the reviewers:

In this work the partition behavior of phenols using ethanol-salt-based aqueous two phase systems (ATPS) was evaluated. The aim was the recovery of phenolic compounds with antioxidant capacity from eucalyptus wood industrial wastes. Experiments were planned to study the influence of several parameters on phenols partition, including type of inorganic salt (ammonium sulphate, a mixture of monopotassium phosphate and potassium diphosphate and potassium diphosphate), tie-lie lenght (TLL), volume ratio (Vr), settlement time and temperature. Phenols could be recovered preferently from the top or bottom phases depending on the salt used. It was demostrated that tie-lie lenght, volume ratio and temperature had influence on phenols partition. The highest total phenols yield 5,36 mg gallic acid equivalent (100 mg oven dried wood)-1 and FRAP antioxidant activity, 20 mmol AAE (100 g oven dried wood)-1, was obtained using ATPS formed by 40.6% (w/w) ethanol and 12% (w/w) of ammonium sulphate at 65ºC. Analysis of the extract by RP-HPLC-ESI-TOF confirmed the presence of the phenolic compounds with potential antioxidant activity, namely, ellagic acid, myricetin 3-O-rhamnoside and quercetin 3-glucoside.

Six treatments (one control and five decoration coatings) were applied to radiata pine wood treated with micronized copper azole for outdoor use at a rate of 3,08 kg/m3 retention. One decoration coating was applied prior to impregnation, prestain and two decoration coatings were applied in a mixture with the micronized copper azole preservative Black Cylinder and Red Cylinder. The following two varnishes were tested: a water-based varnish and a solvent-based varnish.Additionally, untreated radiata pine specimens were tested as a reference. The changes in the gloss and color of these five decorative coatings were evaluated after undergoing natural aging tests for three months and accelerated aging trials during exposure to ultra-violet radiation of 340 nm for 500 hours. In the accelerated aging trials treatments, changes in gloss and color showed the lowest variations in treatment trials prestain and Black Cylinder and the highest variations in treatment trial Red Cylinder. In the aging tests trials, changes in gloss and color showed the lowest variations in treatment trials prestain and Black Cylinder. The costs of each decorative coating were assessed in terms of performance according to timber volume coated. The lowest cost of the three decoration treatments was prestain, with a value of 16 US$/m3, followed by Black Cylinder with a value of 24 US$/m3. Compared with the alternative siding products available in the market, such as fiber cement and vinyl siding, colored wood treated with prestain is competitive with vinyl siding, with 58% lower costs than fiber-cement.

The objective of this work was to study the effect of torrefaction temperature on properties of patula pine (Pinus patula) wood that could be of interest for further thermochemical processing. Torrefaction temperature was varied from 200 to 300 °C for 30 minutes using a batch spoon type reactor. Raw and torrefied materials were characterized for proximate and ultimate analyses, thermogravimetry, and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Results showed that torrefied pine has greater higher heating value and chemical exergy due to the reduction of O/C and H/C ratios. Compared with raw biomass, the material torrefied at 200 and 250 °C did not present significant changes  in chemical composition and thermal behavior. Conversely, material torrefied at 300 °C did show important changes in both chemical composition and thermal behavior. Py-GC/MS results suggested that the main constituents of biomass, i.e., hemicellulose, cellulose and lignin, suffer a progressive thermal degradation with increase in torrefaction temperature.

Chemical modification of wood with isopropenyl acetate (IPA) using iodine (I2) as catalyst has been carried out. Rubber wood (Hevea brasiliensis) specimens were reacted with IPA using iodine (I2) catalyst at 95°C up to 10 h under solvent free conditions. The effect of catalyst concentration and reaction time was studied. The extent of acetylation was measured by determining weight percent gain and the modified wood was characterized by FTIR-ATR and 13C NMR spectroscopy. It was found that IPA in the presence of iodine is an excellent acylating reagent for wood. Modified wood exhibited highdimensional stability

Este es un estudio exploratorio para dar uso a la madera de Eucalyptus urophylla en la elaboración de tableros aglomerados de partículas. Por lo tanto, los objetivos fueron determinar sus propiedades físico-mecánicas y evaluar los resultados bajo norma Alemana Instituto Alemán de Normalización (DIN) y Venezolana Comisión Venezolana de Normas Industriales (CONEVIN). Para los tableros de densidad real de 731 kg/m3, la absorción de agua promedio a 2 y 24 horas no cumple de acuerdo a las normas, para el caso de los tableros de densidad real 831 kg/m3 cumple con la norma. La variación del espesor (hinchamiento) promedio por inmersión en agua a 2 horas para los tableros con densidad de 731 kg/m3 no cumple con lo exigido en ambas normas, pero si cumple con los requerimientos para 24 horas. Para el caso de los tableros con densidad de 838 kg/m3 la variación de espesor a 2 y 24 horas cumplió con las normas. Respecto de las propiedades mecánicas, tanto el módulo de ruptura en flexión estática como la tensión perpendicular (adhesión interna) para ambos niveles de densidad superaron el valor mínimo aceptado en las normas, demostrando que las partículas de madera de Eucalyptus urophylla presentan características tecnológicas adecuadas para la fabricación de tableros de partículas de densidad media.This is an exploratory study on the feasibility of using Eucalyptus urophylla wood for the production of particleboards. Therefore, the aims were to determine their physical and mechanical properties and to evaluate the results with German Standards Institute (DIN) and Industrial Standards Commission Venezuelan (COVENIN). For boards with a real density of 731 kg/m3, the average water absorption at 2 and 24 hours does not meet the standards, in the case of real density boards 831 kg/m3 that fulfilled with both standards. The average water absorption at 2 and 24 hours of boards for the actual density of 731 kg /m3 did not comply with the requirements for both standards, unlike the particleboards with density equal 831 kg/m3 that fulfilled with them. The average thickness variation (swelling) by immersion in water for 2 hours for boards with a density of 731 kg/m3 did not meet the requirements of both standards, but meet the requirements for 24 hours. In the case of boards with a density of 838 kg /m3, thickness variation at 2 and 24 hours meet with the standards. Regarding mechanical properties both, the modulus of rupture in static bending and perpendicular tension (internal bond) for both real density levels exceed the minimum accepted by standards, demonstrating that E. urophylla wood exhibit suitable technological characteristics for particleboards medium density manufacture.