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

The properties of CLT can be affected by the type of adhesives used. The thermal properties of the adhesive that joins the timber together is essential to determine the thermal endurance of the CLT product. In this study, two types of adhesives were used to join the cross laminated timber (CLT) manufactured from Acacia mangium namely phenol resorcinol formaldehyde (PRF) and one component polyurethane (PUR). The thermal properties of the adhesives, A. mangium wood and the gluelines were determined via Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA) tests. The TGA test showed that PRF adhesive had higher degradation temperature at 530 ˚C compared to PUR adhesive at 430 ˚C. Meanwhile, the PRF adhesive as a glueline in CLT also showed better thermal resistance where a higher amount of residue of 20,94 % was recorded at temperature up to 900 ˚C compared to PUR glueline with 18,26 % residue. The integrity of the CLT over temperature were determined via DMA test and the results showed that PRF adhesive as glueline had superior properties, indicating better interfacial bonding with the woods.

The search for new technologies to improve adhesives and the properties of reconstituted wood panels is constant, and nanotechnology is a tool for this purpose. The aim of this study is investigating the effect of adding nanocellulose in the formulation of the adhesive phenol-formaldehyde on the physico-mechanical properties of Pinus taeda plywood panels. Three ratios of nanofibrillated cellulose (NFC) were added to the adhesive formulation used to produce plywood panels: 0,026 %, 0,038 % or 0,064 %. The panels were tested according to the European standards; apparent density, resistance to parallel and perpendicular flexure and glue line shear strength were determined after 6 hours of boiling and after the boiling cycle for the 1st glue line (face) and 2nd line (core). The use of NFC in the adhesive caused an increase of viscosity and reduction of the gel time of the adhesive. The apparent density of the panels was not influenced by the addition of NFC, but the properties of parallel bending, perpendicular flexing and glue line shear were sensitive to the addition of NFC. The NR2 treatment (0,038 % NFC) presented the best results in the mechanical tests.

The radial variation in cell morphology of ten-year-old Melia azedarach trees planted in northern Vietnam was experimentally investigated. The earlywood fiber lumen diameter and latewood fiber lumen diameter were almost unchanged from pith to 6th ring before significantly decreasing and remaining constant from 7th ring outwards. In contrast, fiber cell wall thickness in both earlywood and latewood increased from pith to 7th ring before becoming stable towards the bark. The maturation age of earlywood vessel lumen diameter estimated by segmented regression analysis indicated that wood of the Melia azedarach could be classified into core wood and outer wood, and the boundary between core and outer wood may be located at 7th ring from pith. This should be taken into account in wood processing using M. azedarach grown in northern Vietnam.

The present study was carried out to evaluate the effects of microwave (MW) radiation on viability of wood decaying fungi. The white rot (Trametes versicolor) and brown rot (Rhodonia placenta) fungi were grown on bamboo culm-samples. The mycelium growths were observed in controlled as well as microwave treated samples. The results showed that the viability of fungi decreased according to the applied MW time. This study proved the ability of the microwaves and exposure time MW3 (180 seconds) to kill the fungal colonies and do not allow for the growth of fungal spores, means the rate of growth of fungal colonies is inversely proportional to time of microwave exposure.

The aim of this study was to evaluate the changes in the characteristics of Eucalyptus spp. from Paraíba Valley region, Sao Paulo - Brazil after torrification process. Torrification is a thermochemical process that occurs at temperatures lower than the pyrolysis process as a pretreatment to improve biomass characteristics for use as biofuel energy in power generation. An experimental study was carried out in a batch reactor at three temperatures (240 °C, 260 °C and 280 °C) with residence time of 30 and 60 minutes. At the indicated operating conditions by elemental analysis, higher heating value and thermogravimetric analysis were evaluated. Result showed that there was a reduction in the oxygen/carbon (O/C) and hydrogen/carbon (H/C) ratios, causing an increase in the thermal energy quality of torrified wood, about of 28 % and 47 % at temperatures of 260 °C with residence time of 60 minutes and 280 °C with 30 minutes, respectively. A thermogravimetric analysis showed that at 260 °C the hemicellulose was almost completely degraded leaving the fuel in better conditions for combustion or gasification processes.

Chemical compounds of wood preservation from plants vary and are not known specific to the species. Chemical analysis of plants is responsible to ensure active compound in natural extracts wood treatment. There are many sources of natural extracts found in Indonesia that were explored for wood preservatives chemicals. They are bark of acacia and alstonia, leaves of orthosiphon and azardirachta and Dioscorea tubers. The present study was aimed at investigating the variation of the chemical constituent of natural extracts material of wood preservative through GC-MS analysis. Five natural extract sources were acacia bark (Acacia spp.), pulai bark (Alstonia scholaris), kumis kucing leaves (Orthosiphon spp.), mimba leaves (Azardirachta indica), and gadung tubers (Dioscorea spp.). Two non-polar solvents, i.e., n-hexane and petroleum ether were used for five natural source extractions following ASTM soxhlet extraction. The research showed that triterpene and fatty acid derivatives were the major compounds present in five natural extracts. They were lupeol; 7,22-Ergostadienone; Lup-20(29)-en-3-one; Lup-20(29)-en-3-ol, acetate, (3.beta.)-; urs-12-en-3-one; ethanol,2,2-diethoxy-; stigmasta-5,22-dien-3-ol, acetate,(3.beta.)-; 5H-3,5a-Epoxynaphth(2,1-c)oxepin, dodecahydro-3,8,8,11a-tetramethyl-; linoleic acid; naphthalene, 1-methyl-. These compounds have been assigned as the possibly responsible to against termites or fungi.

Nota: este documento forma parte de la colección de revistas de la Biblioteca Universitaria (Universidad de Oviedo). Le rogamos que se ponga en contacto con la biblioteca del centro para comprobar la disponibilidad y gestionar la obtención del documento original o una copia del mismo.

Nota: este documento forma parte de la colección de revistas de la Biblioteca Universitaria (Universidad de Oviedo). Le rogamos que se ponga en contacto con la biblioteca del centro para comprobar la disponibilidad y gestionar la obtención del documento original o una copia del mismo.

Nota: este documento forma parte de la colección de revistas de la Biblioteca Universitaria (Universidad de Oviedo). Le rogamos que se ponga en contacto con la biblioteca del centro para comprobar la disponibilidad y gestionar la obtención del documento original o una copia del mismo.

Nota: este documento forma parte de la colección de revistas de la Biblioteca Universitaria (Universidad de Oviedo). Le rogamos que se ponga en contacto con la biblioteca del centro para comprobar la disponibilidad y gestionar la obtención del documento original o una copia del mismo.