Maderas. Ciencia y tecnología

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List of Papers (Total 134)

THE INFLUENCE OF SOME FACTORS ON THE TIMBER DRYING PROCESS, ANALYZED BY A GLOBAL SIMULATION MODEL

A model for the simulation of timber drying in a batch kiln has been used for the investigation of a set of different questions related to this drying process. The model is global in the sense that it takes into account that the drying air local climate changes as it passes through the kiln load. In Scandinavian, practice kiln stacks are normally built from boards of random...

SECADO INDUSTRIAL DEL PINO RADIATA: TIEMPO DE ESTERILIZACIÓN CON CALOR Y EVOLUCION TEMPORAL DE LA TEMPERATURA

In this work were studied the heat sterilization time (HT) and the evolution time of the internal wood temperature during industrial drying of radiata pine. The experimental design included as variable the air temperature of the initial treatments in saturated atmosphere and the wood thickness. The minimal time required to satisfy the demands of HT specify by the NIMF 15 standard...

POLYMER NANOCOMPOSITES: SYNTHETIC AND NATURAL FILLERS A REVIEW

This paper reviews current research, techniques for characterization and trends on the field of nanocomposites. Nanocomposites are new materials made with fillers which have nanosize. These materials have a big potential for applications in the automotive and aerospace industry as well as in construction, electrical applications and food packing. There is a tremendous interest...

MICROSTRUCTURAL AND PHYSICAL ASPECTS OF HEAT TREATED WOOD. PART 1. SOFTWOODS

Heat treatment of wood is an effective method to improve the dimensional stability and durability against biodegradation. Optimisation of a two-stage heat treatment process at relatively mild conditions (<200°C) and its effect on the anatomical structure of softwoods were investigated by means of a light and scanning electron microscopic analysis. Heat treatment did have an...

PROGRAMACIÓN MULTIOBJETIVO DE MÁQUINAS MOLDURERAS A TRAVÉS DE ALGORITMOS MEMÉTICOS

This work presents a multiobjective optimization algorithm based on a variant of the evolutionary programming field called memetic algorithms (MA). This algorithm was proposed by the authors, combines genetic evolution with local search, in the same way as traditional MA, but with the use of independent populations for each objective, as well as a mechanism to find compromise...

THE WOOD CELL WALL AT THE ULTRASTRUCTURAL SCALE - FORMATION AND TOPOCHEMICAL ORGANIZATION

The macromolecular organization of the secondary wall of the cells from tree xylem is in large part responsible for the mechanical and physiological properties of wood. Modeling secondary walls of wood is difficult because information about their macromolecular architecture at the ultrastructural scale is missing. Numerous microscopic studies have provided views of the...

HIGH-FREQUENCY ELECTRIC CURRENT FOR DRYING OF WOOD - HISTORICAL PERSPECTIVES

Among the many interesting topics in the field of Wood Science and Technology is a fascinating story about research and development on drying wood products with high-frequency electric current. Historically, it can be traced back over decades. Heat transfer to and evaporation of moisture from wood may be accomplished with high frequency current depending on its dielectric...

DEVELOPMENT OF ELASTIC STRAIN AND MECHANO-SORPTIVE STRAIN DURING CONDITIONING OF EUCALYPTUS CAMALDULENSIS LUMBER IN BATCH KILN

ABSTRACT Final conditioning of 25mm thick dried E. camaldulensis lumber was carried out in small capacity batch drying kiln in laboratory, and the elastic (EL) strain and mechano-sorptive (MS) strain was analyzed by slicing method. Mean moisture content(MC) of boards increases 2.5-3.0%, while surface MC increases from 9.8% to 14.2% and center MC always keeps at 12.3% or so...

Estudio del contenido y la calidad de la lignina mediante Pirólisis analítica en madera de Pinus caribaea

This work shows the lignin content determined as well as its quality (H/G ratio) in wood samples of Pinus caribaea var caribaea from three sites at Pinar del Río Province, Cuba. The study was carried out at the Tropical Scientific Investigation Institute, Lisbon, Portugal (Project GEMA). The Analytical pyrolysis was used as analytical method. The results represent the average of...

Estudio Teórico-Experimental sobre la degradación térmica de vigas de Eucalyptus

Thermal action on timber causes it to degrade through combustion of its chemical components, which leads to the release of vapors, combustible gases and char. This diminishes its load capacity due to the reduction of its cross section by charring and to changes in its mechanical properties of strength and stiffness as a function of its exposure to high temperatures. This paper...

EXTRAÍBLES DE CORTEZAS CHILENAS: EFECTO SOBRE LA LUMINISCENCIA DE BACTERIAS

Bioluminescence decrease of bacteria as a biological activity indicator for bark water extracts was determinate. Four Chilean barks were tested. A different reduction on bioluminescence depending on bark species was observed. Increasing time of thermal treatment of bark (24, 48, 72 and 144 hours with 103ºC) produced a reduction of the biological activity of extracts. The study...

EXPORTACIÓN DE MADERA ASERRADA DE CONÍFERA CHILENA: UN ANÁLISIS DE SU COMPETITIVIDAD

The competitiveness is analyzed on the principal markets of the Chilean exports of saw wood of radiata pine in the period 1994-2004 (Contreras, 2006). The methodology applied is "Competitive Analysis of Nation" (CAN), created by the Economic Commission for Latin America and the Caribbean (CEPAL), who allows to obtain a dynamic vision of the situations of competitiveness of the...

A mesoscopic drying model applied to the growth rings of softwood: mesh generation and simulation results

A mesoscopic drying model that enables the drying simulation of quartersawn and flatsawn wood sections consisting of several growth rings is presented. The procedure to generate the virtual board description directly from real sample images is also described. This virtual structure accommodates the prominent sample features, including its geometrical and physical properties...

PHYSICAL AND MECHANICAL PROPERTIES OF PANEL BASED ON OUTER BARK PARTICLES OF WHITE BIRCH: MIXED PANELS WITH WOOD PARTICLES VERSUS WOOD FIBRES

The use of outer white birch bark in canoes is an example of its oldest use by the first nations in Canada. This use confirms the hydrophobic characteristics of this bark, which can be capitalized on by using it in the outer layers of three-layer mixed composite panels in order to protect them from water infiltration from their surface. These panels were made up of outer white...

PERFORACIONES ESCALARIFORMES EN VASOS DE ÁRBOLES NATIVOS DE CHILE

Perforation plates are openings in the end walls of vessel elements, allowing water flow between neighboring vessel elements in longitudinal direction. There are many types of perforation plates, simple, scalariform, reticulate and foraminate. In this study a classification and description of scalariform plates was made, as a contribution to the knowledge of anatomic wood...

APPLICATION OF X-RAY TECHNIQUE IN NONDESTRUCTIVE EVALUATION OF EUCALYPT WOOD

X-rays were initially used for the inspection of special-purpose wood pieces for quantitative evaluation of wood properties of different species. X-ray densitometry has had its use expanded in dendroclimatology of Picea engelmannii trees. Subsequent laboratories developed applications of X-ray densitometry for environmental, wood science and technology, and related areas. This...

FABRICACION DE PELLETS DE CARBONILLA, USANDO ASERRIN DE Pinus radiata (D. Don), COMO MATERIAL AGLOMERANTE

In the present study, it was used charcoal of vegetal coal and sawdust of Pinus radiata (D. Don) to manufacture pellets, these had similars characteristics by weight, volume and density, keeping as the only variable, the sawdust and charcoal quantity of each pellet. Using a manual screw press, was manufactured a total of 1180 pellets with 15 different charcoal and sawdust...

Bending strength and stiffness of structural laminated veneer lumber manufactured from fast-growing Argentinean Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in specimens of laminated veneer lumber (LVL) manufactured from Argentinean Eucalyptus grandis and tested edgewise according to European standards. For this purpose an empirical research project with one sample containing 44 specimens with nominal sizes of 24.3...

Evolución del Módulo de Elasticidad Longitudinal entre 10°C y 100°C en piezas de Pinus radiata usando una técnica de evaluación no destructiva

We measured the natural frequency of vibration in 5 wood specimens of Pinus radiata D. Don (1 inch thickness) in the range of temperature from 10°C to 100°C at intervals of 10°C. The samples were placed as a simple-beam and the vibration was induced by a quick shot. The signal of vibration was digitized and stored on a personal computer at a frequency acquisition of 1 kHz. At the...

Distribution of Within-Ring Internal Checking in Pinus radiata Grown in Southern Chile

The increase of Pinus radiata plantations in Chile has brought larger annual volumes to the industry and the opportunity to process them into value-added products. Within-ring checks constitute an important problem that may affect the appearance quality of lumber. This problem occurs in the early wood portion of sapwood growth rings in dry lumber and can only be seen when the...

THE DENSITY, COMPRESSION STRENGTH AND SURFACE HARDNESS OF HEAT TREATED HORNBEAM (Carpinus betulus L.) WOOD

The heat treatment of wood is an environment-friendly method for wood preservation. The heat treatment process only uses steam and heat, and no chemicals or agents are applied to the material during the process. Tests have shown no harmful emissions are apparent when working with the material. This process improves wood’s resistance to decay and its dimensional stability. In this...

MODEL TO ASSESS ENERGY CONSUMPTION IN INDUSTRIAL LUMBER KILNS

In this work, a kiln energy model was developed with the main objective of assessing energy consumption in industrial lumber kilns. The model simulates kiln energy consumption on the basis of a simplified description of kiln technologies, energy systems and lumber characteristics, and it requires a minimum set of empirical parameters that are calibrated in practice. In this study...

CREEP BEHAVIOR OF BORATE-TREATED STRANDBOARD: EFFECT OF ZINC BORATE RETENTION, WOOD SPECIES, AND LOAD LEVEL

Creep performance of zinc borate-treated strandboard from southern pine (Pinus taeda L.) and red oak (Quercus falcata) was investigated at 250C temperature and 65% relative humidity. It was shown that the borate treatment had some significant effect on creep deflection of the test panels, and the effect varied with wood species. There was no significant effect of creep loading on...

ESTUDIO DE ALGUNAS PROPIEDADES FÍSICAS DE LA MADERA DE Acacia melanoxylon R. Br. EN ARGENTINA

The aim of this research was to determine density, maximal swelling and shrinkage, anisotropy of swelling and shrinkage and fibre saturation point on samples of Argentinean Acacia melanoxylon R Br. Ten trees were randomly selected from two sites located in Buenos Aires Province and samples were obtained at breast height. Physical properties were determined according to the...

FUERZAS DE SUPERFICIE Y ADHESIÓN EN SISTEMAS CELULÓSICOS: NUEVA FORMA DE EVALUAR FIJACIÓN/DISPERSIÓN DE RESINA EN LA FABRICACIÓN DE PAPEL/CELULOSA

Surface and adhesive forces between colloidal wood particles of resin and fiber dominate the behavior and final properties of paper and cellulose. This paper describes the use of Atomic Force Microscopy (AFM) to measure the interaction force between a resin "functionalized" substrate and a glass microsphere in aqueous pH-controlled electrolyte solutions at ambient temperature...