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Kosmos
Astronomia Astrofizyka
Inne

Kultura
Sztuka dawna i współczesna, muzea i kolekcje

Metoda
Metodologia nauk, Matematyka, Filozofia, Miary i wagi, Pomiary

Materia
Substancje, reakcje, energia
Fizyka, chemia i inżynieria materiałowa

Człowiek
Antropologia kulturowa Socjologia Psychologia Zdrowie i medycyna

Wizje
Przewidywania Kosmologia Religie Ideologia Polityka

Ziemia
Geologia, geofizyka, geochemia, środowisko przyrodnicze

Życie
Biologia, biologia molekularna i genetyka

Cyberprzestrzeń
Technologia cyberprzestrzeni, cyberkultura, media i komunikacja

Działalność
Wiadomości | Gospodarka, biznes, zarządzanie, ekonomia

Technologie
Budownictwo, energetyka, transport, wytwarzanie, technologie informacyjne

MADERAS: Ciencia y tecnología

Scielo Chile

Effects of accelerated and natural weathering on the molecular weight distribution (MWD) and crystallinity of polypropylene (PP) in wood plastic composites (WPC) were investigated. The composites were produced from pine fibers (60%) and PP (40%). Prolonged weathering caused an increase in wood degradation and erosion thereby leaving cracks and ‘‘pits’’ on the surface. Pyrolysis gas chromatography-mass spectrometry (Py GC-MS) revealed that PP dominated the weathered surface due to wood degradation. For matrix analysis, PP was extracted using 1,2,4- trichlorobenzene. Crystallinity and molecular weight distribution of PP were monitored by differential scanning calorimetry (DSC) and gel permeation chromatography (GPC), respectively. PP’s crystallinity increased upon longer exposure time. The weight and number average molecular weight (Mw and Mn) decreased with an increase in weathering duration. An increased polydispersity (PD =Mw/Mn) implies that a secondary cross-linking process occurred during weathering.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300002&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

Heat treatment of Oriental-beech (Fagus orientalis) wood was carried out by hot air in an oven for 2, 4, and 8 h at 140, 170, and 200°C. After heat treatment, some physical characteristics such as surface roughness, color, glossiness, and mass loss of Oriental-beech wood specimens were measured. Our results showed that heat treatment caused decrease in surface roughness, glossiness, and mass loss values of Oriental-beech (Fagus orientalis) wood specimens. The decrease in lightness at all temperatures indicates that the specimens become darker with the treatment time. While, a* coordinate (red component) decreased as temperature increased, b* coordinate (yellow component) initially increased at 140°C and then decreased at 170°C and 200°C.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300003&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

This paper deals with the effect of vacuum-pressure impregnation of Poplar wood (Populus alba) by aqueous solutions of sucrose and sodium chloride on its physical properties. Groups of samples with different concentrations of substances in the aqueous solution were compared within each other and also with a reference (non-impregnated) group. The specimens from all groups were tested for density, moisture absorption and dimensional stability. The obtained data were statistically analysed and compared each other. The most satisfying final properties were achieved in impregnation of sucrose with concentration of 6,25 g/100 ml H2O. The retention was 31 kg m-3 (WPG around 8 %). The values of ASE (anti-swelling efficiency) reached to 36 % and MEE (moisture exclusion efficiency) was reduced by 33 %.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300004&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

Plum (Prunus domestica) is one of the most widespread species of fruit trees in Asia and South-East Europe. There are large quantities of fruit wood trees without suitable usage in world. The aim of this research was to examine biometrical and chemical properties of the plum wood and its application in the pulp and paper industry. Five normal plum trees were randomly selected from Shahriyar province, Iran. A log cut down at stem (breast height) and branch for each of trees. The pith parts of cross-section were removed to examine the chemical (according to the TAPPI standard) and biometrical properties (according to the Franklin method). Results indicated that there were significant differences between stem and branch samples in fiber diameter and lumen diameter. Types of wood (branch and stem) had not significant differences on the chemical properties and fiber length, cell wall thickness and morphological properties. Among all of studied properties, the lignin, cellulose, fiber diameter, fiber lumen diameter, cell wall thickness and flexibility coefficient in branch wood is higher than stem wood. Although Runkel and flexibility coefficients of stem and branch fibers are lower than the accepted standard, but because of closing amount of lignin, extractive composition and fiber length to hardwood species, it can solve some of the problems of the lack of raw materials for paper production.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300005&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

Charcoal is one of the main forestry products and Brazil is the world’s largest producer. Its production from native species is estimated at 30-35% of total output. One of the major problems of the iron and steel industry is charcoal consumption, especially in terms of environmental and social aspects. Therefore, the use of reforestation species must be increased. Considering most of the energy forests in Brazil are planted with eucalyptus, the present work aims to contribute to the identification of charcoal origin through anatomical analysis of Eucalyptus and Corymbia. The wood samples were carbonized in a muffle furnace during 7h to a maximum of 450ºC. Anatomical analysis was done according to IAWA Committee. We found few works with charcoal anatomy and the species analyzed were not characterized. The results on charcoal are very close to previous studies of wood anatomy. But, we recommend the comparison of materials of similar features, enhancing the visual acuity, particularities of each material and modifications that might happen. We believe that this analysis is an accurate tool to identify the source of charcoal and can help to guarantee the sustainability of the charcoal supply chain.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300006&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

This research was developed after consultations with tropical timber exporters, who were facing problems with the colors of the species under study. This work aimed at characterizing Simarouba amara tropical wood color and verifying possible differences between the colorimetric parameters determined for the tangential and the radial directions of the wood, kiln-dried and air-dried. S. amara wood presents a grayish-white color. This color is mainly characterized by the b* coordinate (yellow pigment). Depending on the drying method used, the wood may present different colors for both tangential and radial directions. In both drying methods conducted, the wood presented lighter color in the tangential direction. Kiln-drying appeared to reduce S. amara wood lightness.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300007&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

El objetivo del trabajo fue analizar los patrones de variación axial y radial de la densidad y morfometría celular de la madera de sauce americano y determinar la edad de transición de madera juvenil a madura. Se muestrearon cinco árboles de 45 años de Salix babylonica de Entre Ríos, Argentina. Se tomaron muestras a tres alturas en el fuste y en 9 posiciones radiales y se determinó la densidad básica y la morfometría de fibras y vasos. Los patrones de variación radial evidenciaron un leve aumento de magnitud con la edad, mientras que la mayor variación axial se manifestó mayoritariamente entre la base y la altura de 1,3m el fuste, presentándose diferentes tendencias de acuerdo a la variable. Dependiendo de la variable analizada, la edad de transición entre madera juvenil y madura fue de 5 a 10 años o de 10 a 15 años. La longitud y ancho de fibras y el diámetro de vasos fueron los primeros parámetros en madurar. Los valores promedio de las variables de la madera juvenil y madura no mostraron diferencias importantes entre los leños, por lo tanto podrían considerarse como homogéneos desde el punto de vista anatómico y de densidad.The aim of this work was to determine the patterns of axial and radial variation of the density and cellular morphometry of american willow wood, for determining the age of transition from juvenile to mature wood. The study was conducted on five trees of a 45- years-old plantation of a clone of Salix babylonica, from Entre Rios, Argentina. Samples were taken at three heights and at 9 radial positions of the stem for the determination of basic density and morphometry of fibers and vessels. The radial variation patterns showed a slight increase in magnitude with age, whereas the axial variation showed up between the base and a height of 1.3 m in the stem, presenting different tendencies according to the variable. Depending on the analyzed variable, the age of transition between juvenile and mature wood was 5 to 10 years, or 10 to 15 years. Fiber length and width and vessel diameter were the first characters to mature. The average values of the properties of juvenile and mature wood showed no substantial differences between logs, therefore they could be considered as anatomically and density homogeneous.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300008&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

In this study, it was aimed to investigate some surface characteristics such as surface roughness, color, and glossiness of Scots pine (Pinus sylvestris) wood specimens after 500 hours artificial weathering exposure. Our results showed that surface characteristics of thermally modified Scots pine gave better results than unmodified Scots pine after artificial weathering. Artificial weathering caused an increase in surface roughness and a decrease in glossiness of Scots pine wood. Results showed artificial weathered wood become darker, reddish, and yellowish. Generally, higher duration and temperature for Scots pine resulted in better surface characteristics of Scots pine after artificial weathering

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300009&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

Dimensional stability of wood plastic composites (WPCs) made from polypropylene and pine wood flour with and without coupling agent was investigated. The pine wood flour was prepared from wood chips which had been immersed, respectively, in boiling water for 1 h, 3 h, and 5 h or in distilled water for 1 day, 3 days, and 5 days at room temperature. It was found that thickness swelling (TS) and water absorption (WA) of the WPCs made using extracted wood were lower than those of WPCs produced with unextracted wood. The TS and WA values of WPCs decreased with extraction duration both for cold and hot water extraction. The effect of hot water extraction on the TS and WA properties of the WPCs was more pronounced than cold water extraction.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300010&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

El objetivo del trabajo fue evaluar tensiones de crecimiento en Eucalyptus dunnii y determinar el efecto de las propiedades físicas de la madera sobre esta variable. Se muestrearon 45 árboles de un ensayo de 19 años situado en la provincia de Corrientes, Argentina. Se realizaron determinaciones de tensiones de crecimiento a través de dos métodos: indicador de tensiones de crecimiento (GSI, CIRAD-Forêt) e índice de rajado en rollizo (IR). Se midieron las propiedades físicas, densidad básica y contracción volumétrica total y se determinó la variación radial de la densidad básica. Los resultados de GSI e IR mostraron valores más bajos que los citados para la especie (GSI: 0,0763±0,0251 mm e IR: 0,43± 0,31 %) y tuvieron buena asociación entre sí (r: 0,71). Se encontró una asociación baja entre tensiones de crecimiento con las propiedades físicas de la madera, densidad básica (r: 0,35 - 0,39) y contracción volumétrica total (r: 0,29 - 0,35). Los niveles de asociación aumentaron cuando las correlaciones se hicieron entre las estimaciones de tensiones de crecimiento y la tasa de cambio radial de la densidad básica (r: 0,59 - 0,52).To evaluate growth stresses in Eucalyptus dunnii and determine the effect of physical wood properties on that variable, a total of 45 trees were sampled from a 19-years-old trial located at Corrientes, Argentina. Growth stresses were determined using the growth stress indicator (GSI, CIRAD-Forêt) and the log end split index (IR). The physical wood properties basic density and total volumetric shrinkage were measured and the pith-to- bark gradient of the basic density was determined. GSI and IR values obtained were lower than those cited for the species (GSI: 0,0763 ± 0,0251 mm and IR: 0,43 ± 0,31 %) and showed good association between themselves (r: 0,71). A low association between growth stresses and the physical wood properties basic density (r: 0,35 - 0,39) and volumetric shrinkage total (r: 0,29-0,35) was founded. The association levels were higher when growth stresses (GSI and IR) and the pith-to-bark gradient of the basic density (r: 0,59-0,52) were correlated.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000300011&lng=en&nrm=iso&tlng=en 2014/08/07 - 22:35

Wood heat treatment is an attractive alternative to improve decay resistance of low natural durability of wood species. Decay resistance is strongly correlated to thermal degradation of wood cell wall components. Some recent studies proposed the use of wood mass loss during the heat treatment as a valuable marker to predict final properties of the material (Hakkou et al. 2006, Welzbacher et al. 2007). In this study, heat treatment was carried out in a relatively low temperature (230˚C). Mass loss kinetics was studied using equipment, specially conceived to measure sample’s mass during the thermal treatment. Laboratory experiments were performed for heating rates of 1˚C min-1. Mathematical model for kinetics of pyrolysis process was used and validated. During the pyrolysis of dry wood samples under inert atmosphere, measurements of temperature distribution and dynamic weight loss were performed. Five different wood species Fagus sylvatica (Beech), Populus nigra (Poplar), Fraxinus excelsior (Ash), Pinus sylvestris (Pine) and Abies pectinata (Silver Fir) were investigated. The unsteady-state mathematical model equations were solved numerically using the commercial package Femlab 2.0. A detailed discussion of the computational model and the solution algorithm is given. The validity of different model assumptions was analyzed. Experimental results were compared with those calculated by the model. Acceptable agreement was achieved.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200001&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

Decayed-wood samples were collected from a naturally-infected bridge made of Quercus robur. Fruiting bodies of the white-rot basidiomycetes Hymenochaete rubiginosa and Stereum hirsutum were sampled. The white-rot fungus Fuscoporia ferrea and the secondary saprobiont Mycena galericulata were identified from the rotten wood by means of rDNA-ITS sequencing. The topochemistry of lignin degradation within individual cell-wall layers was determined by cellular UV-microspectrophotometry (UMSP) at 278 nm wavelength. Increased delignification occurred in compound middle lamella regions (CML), secondary wall layers of fibres (S2), longitudinal and ray parenchyma cells as well in vessels. The highest lignin content at initial and medium decay was recorded in the CML, whereas in advanced decay secondary wall layers of the vessels exhibited the highest content of residual lignin. In all stages of degradation, the S2 layers of fibres had the lowest lignin amount.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200002&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

A new zero-waste and zero-pollution composite adhesive labeled Chinese fir-based adhesive for exterior plywood was synthesized by blending alkaline Chinese fir (Cunninghamia lanceolata) liquid with a small amount of phenol-formaldehyde (PF). The free phenol and free formaldehyde content of the Chinese fir-based adhesive were sharply decreased compared to normal PF resin by more than 50%. The synthetic adhesive show with excellent water resistance and environmental friendliness, which had a 28h boil-dry-boil wet bonding strength of 1,73MPa according to standard JIS K6806-2003 and a formaldehyde emission of 0,045mg/L according to standard JIS A1460-2003. The structural properties and their thermal properties of cured adhesives were evaluated using Fourier transform infrared (FT-IR) and differential scanning calorimetry (DSC). The FT-IR analysis confirmed the expected chemical structure as the Chinese fir liquid reacted with formaldehyde and phenol which occurred at the wavenumbers of 1733, 1698, 1652cm-1 and 1077, 1048 cm-1. Although the DSC results indicated that the Chinese fir-based adhesive's curing need higher temperature than the control PF resin, the higher curing temperature hardly cripple the availability of Chinese fir-based resin in the plywood production.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200003&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

World production of wood based panel has grown from 63,1 million cubic meters in 2005 to 75,5 million m³ in 2009, a 12 million m³ rise in production. China is the world's largest wood based panel’s manufacturer. The Turkish wood based panels industry has shown a tendency of fluctuating during this time. Turkey, as the world’s 4th largest producer of wood based panels, is an important contributor to the industry. Turkey has made great strides in the last 20 years in the forest products industry. Both the development of new materials and techniques of domestic and international market demand have played a decisive role. Turkey's wood panel production has gone from 100000 m³ in the early 2000s, to 5,5 million m³ of production in 2010. The sector's total production capacity is approximately 9 million m³. The results obtained thus far indicate that the Turkish wood based panel industry demand for raw material is not being met by the GDF's chip wood fiber production. Where the raw material supply problem in the industry, as well as the problems encountered in the forest and on the basis of the villagers living adjacent to, not to the time of product problems related to storage and transportation of raw materials and other related problems are bottlenecks. We examine problems related to the provision of raw materials and raw materials research, the need for future estimates of the level at which the world and close to the periphery countries will be examined, wood composite panel production and trade policy recommendations will be developed.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200004&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

The shrinkage at the cellular level was determined in the transverse plane of wood using an environmental scanning electron microscope (ESEM). The whole procedure is based on pairs of images grabbed with the same imaging conditions (magnification, working distance, voltage) without removing the sample from the chamber: one image collected at saturated conditions (1067 Pa, 1°C) and the other at air-dry state (533 Pa, 16°C). A closed chain of the same reference points chosen from the anatomical markers was defined on both images at the external part of the zone of interest. A custom software program, called MeshPore, allowed the shrinkage coefficients to be extracted from the slight difference of shape between these two chains. Measurements of transverse shrinkage were performed on earlywood and latewood zones from Norway spruce (Picea abies), only normal wood was studied. The interested zones were isolated from the rest of the annual ring with the aid of a microtome blade, insuring the observations to be done under free shrinkage. As additional features, the changes of the cellular morphology and the cell wall thickness were also evaluated thanks to the resolution provided by the ESEM.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200005&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

In this work the multi-factor, non-linear dependencies between main (tangential) F C and normal (radial) F N cutting forces upon two machining parameters by up-routing and down-routing wood of Douglas fir (Pseudotsuga Menziesii) and Oak (Quercus petraea) were evaluated. The relationships are graphically illustrated and discussed. The obtained data were compared with cutting forces evolution models according to grain orientation from the literature in order to verify if literature statements or models comply with measured data. Evidence of several contradictions was found relative to results from available literature.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200006&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

The objective was to evaluate the elasticity dynamic modulus reduction (MOEd) and deterioration of E. grandis thermorectificated wood by exposure to environmental weathering. Six trees were used to obtain 14 logs of 2,4m, with seven from external (sapwood) and the others from internal (heartwood) part of the trunk. A total of 84 wood samples of 2,5x 5x 50cm were made, with half from the inner and the other from the external trunk portion. 14 treatments were evaluated with six replicates composed of thermorectificated wood submitted two differents times (2 and 4 hours) and three temperatures (200, 215 and 230˚C). An ultrasound Stress Wave Timer device was used to evaluate MOEd and the mass measured by weighing. Samples remained in the decay test field for ten months, and monthly inspected and recorded to xylophogous organism’s occurrence. At the end of this period MOEd and mass were revaluated. The central portion of wood samples were more deteriorated, with mass losses and stiffness losses ranging from (8-56%) and (18-91%), respectively. Lower values ​​were observed in the wood coming from the external portion, with mass losses and stiffness ranging from (3-10%) and (8-20%), respectively. The thermorectificated wood samples were more damaged by action the termites and less by the action of fungi, compared to controls.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200007&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

The health problems amongst musical instrument makers working on the White mulberry (Morus alba), lead to investigate the toxicity potential of wood extractives. Five solvents of different polarity and two methods of extractions were used to ensure a thorough, clear and classified compound removal. The compounds were identified using qualitative GC-mass and the toxicity were determined by studying their effect on termite survival (Reticulitermes flavipes). The results indicated the presence of different compound categories like phenols, higher hydrocarbons, fatty acids, sterols and aromatic components in the extractives. These compounds were not removable by just one solvent and the order of removal was polarity related. The extractives were found toxic towards termites. Resorcinol, which corresponded to the highest proportion of peaks in the GC-mass spectra, has been assigned as the possible compound responsible for the allergic reactions by the artisans.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200008&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

Potential antitermitic properties of some common wood stains were tested against Coptotermes formosanus. Four different wood species treated with 3 different stain chemicals at the 0,1 kg/m2 retention level were exposed to no-choice termite feeding test in laboratory conditions. Mean mass loses, mortality rates and consumption rates were calculated based on weight changes before and after the test. While the hardwood species (beech (Fagus orientalis) and chestnut (Castanea sativa) tested were unaffected by the treatments, the softwood species tested showed drastically reduced mass losses with some stain treatments. Scots pine (Pinus sylvestris) and spruce (Picea orientalis) sapwood exhibited significant reductions in mass losses when treated with the chemical stain.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200009&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

We present a methodology of selecting wood species for architectural purposes, especially when a curved shape is required. First, a mechanical criterion is associated with a morphology, more specifically a characteristic value of stress-strain relation is associated with the attitude of wood for bowing. Second, a filtering is done using data of wood in the green state and in the dry state, and then the wood selection is refined by using relevant criteria related to environment and economic considerations. The following four species are the result of the selection: Sande or Guaimaro (Brosimum utile), Ceiba (Ceiba pentandra), Tamarindo (Dialum guianense), and Roble flor morado (Tabebuia rosea). Information given in the literature is complemented with results of bending experiments when information is lacking. The result emphasizes that tropical species are fitter than temperate species for bowed wood applications.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000200010&lng=en&nrm=iso&tlng=en 2014/05/16 - 00:03

This study aimed to evaluate surface roughness of heat treated Eucalyptus grandis wood after peripheral planning and sanding performed in directions to the grain and against the grain. For machining tests, workpieces were collected from two different regions in the radial direction, as follows: internal, nearby the pit; external, nearby the bark. Heat treatment was carried out by heating samples at a maximum temperature of 190ºC, with total treatment duration of 390 minutes. Heat treated and control samples underwent peripheral planning and sanding tests. The quality of machined surfaces was assessed by means of roughness average (Ra) measurements across and along the grain orientation. Results indicated significant differences in surface roughness as a function of machining feed direction, sandpaper grit size, and heat treatment. Surface roughness has not shown any difference in the radial direction.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100001&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

This study was done to ascertain the suitability of Uganda’s clonal eucalypts for fuelwood. The objectives were to determine: (i) basic density (BD); (ii) calorific value (CV); and (iii) cleavage resistance (CLR) parallel to the grain of widely adopted clones i.e. GU7, GU8, GC540, GC550 and GC796 and to compare these properties with those of their parent materials; i.e. Eucalyptus grandis, Eucalyptus cammaldulensis, and Eucalyptus urophylla. Tests were done according to BS373(1957) and ASTM:E870-82(2006) procedures. Clone GC540 showed the highest BD (664kg/m³), GU7 had the highest CV (17800kJ/kg), GU7 and GC540 had higher values for CLR (20N/mm). BD and CLR means were in-between parent material means for GC clones. All clones had lower values of CV compared to parent materials. It was concluded that clonal wood at 6-7 years remains a viable alternative for fuelwood due to high volume increment per unit time and moderate CLR values to allow ease of splitting.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100002&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

En el presente trabajo se analiza el efecto de la temperatura del termotratamiento sobre la conductividad eléctrica de la madera de pino radiata. Sobre probetas de madera de pino radiata de procedencia País Vasco (España), termotratada a 190ºC y 210ºC por el método Thermowood así como sobre piezas testigo de la misma especie, procedencia y dimensiones, acondicionadas todas ellas hasta masa constante a 20ºC/40%HR, 20ºC/65%HR y 20ºC/90%HR se evaluó la resistencia eléctrica (longitudinal y transversal) y, posteriormente, se ajustó el modelo Samuelsson para modelizar en cada tipo de material la relación humedad de la madera-resistencia eléctrica. Se concluye que la temperatura empleada en el tratamiento térmico de la madera afecta no sólo a la humedad de equilibrio sino, también, a su conductividad eléctrica, siendo máximo este efecto en el tratamiento efectuado a 210ºC.This paper analyzes the effect of heat treatment temperature on the electrical conductivity of radiata pine wood. On specimens of radiata pine of the Basque Country provenance (Spain), heat treated at 190°C and 210°C by the method Thermowood as well as not treated matched samples, conditioned up to constant mass at the standard conditions of 20°C/40%; 20°C/65% and 20°C/90% RH the electrical resistance (longitudinal and transverse) was measured and a Samuelsson model fitted to describe the relationship between the electrical resistance and moisture content of each material. From the data is concluded that the temperature employed in the thermal treatment timber not only affects equilibrium moisture content of wood but also to its electrical conductivity, being this effect maximum in the processing performed at 210°C.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100003&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

Se evaluaron distintas formulaciones de compuestos fabricados en base a polietileno de baja densidad reciclado (PEr) y harinas tanto de corteza como de madera de Pinus radiata, mediante ensayos estandarizados de biodegradación acelerada. Los compuestos tipo Wood Plastic Composites (WPCs) fueron obtenidos mediante moldeo por inyección sin aditivos químicos, a partir de las siguientes mezclas entre PEr-harina en distintas proporciones: 100-0%, 80-20%; 60-40% y 40-60 %. Los ensayos de biodegradación acelerada fueron realizados de acuerdo a la norma ASTM D-2017, bajo condiciones controladas durante 3 meses, usando dos tipos de hongos degradadores, un hongo de pudrición café (Gloeophyllum trabeum) y por un hongo de pudrición blanca (Pleurotus ostreatus). Al término del período de biodegradación se determinó el porcentaje de pérdida de peso de cada tipo de compuesto. Los resultados indicaron que la pérdida de peso de los compuestos aumenta conforme aumenta la proporción de harina en la mezcla, siendo significativamente mayor con el hongo de pudrición café (Gt), más que con el hongo de pudrición blanca (Po). Independientemente del tipo de hongo utilizado, la harina de corteza presentó mayor susceptibilidad a la degradación en comparación con la harina de madera.Composites of wood and bark of Pinus radiata-recycled low polyethylene (RLPE) were submitted to accelerated decay using white and brown rot fungi. These WPCs were obtained by injection molding without chemical additives at proportions: 100-0%, 80-20%, 60-40% and 40-60%. Accelerated decay tests were conducted according to ASTM D-2017-05, using a brown rot fungus (Gloeophyllum trabeum) and a white rot fungus (Pleurotus ostreatus), during 3 months, under controlled conditions. After that, percentage of weight loss of each type of composite was determined. The results shown that the biodegradation of composites increased with increasing of flour in the mixture being higher in brown rot fungus (Gt) than in white rot fungus (Po) treatment. Bark flour had higher susceptibility to biodegradation in comparison with the wood flour.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100004&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

Effects of alfalfa-intercropping and nanosilver-impregnation were studied here on the specific gas permeability of 10-year old Populus nigra var. betulifolia. Specimens were impregnated with a 200 ppm aqueous dispersion of silver nanoparticles under 250 kPa pressure; the results were then compared with the un-impregnated specimens. The size range of silver nanoparticles was 10 to 80 nm. After the initial measurement, specimens were kept in vaporized chamber for six months (43±2°C, and 80±3% relative humidity); permeability was measured every month. Results showed that maximum specific longitudinal gas permeability was observed in the nanosilver-impregnated inner-wood specimens of the treatment with alfalfa (1614,4 × 10-13 m³ m-1), and minimum permeability was found in the un-impregnated outer-wood specimens of the treatment without alfalfa (491,7 × 10-13 m³ m-1) before the vaporization. Vaporized chamber made permeability decrease permeability at the first phases because of the absorption of water vapors and the consequent swelling; however, due to the proliferation of pits and perforation plates by fungi and molds, permeability was eventually increased. Antibacterial property of silver did not significantly decrease the growth of molds and fungi in the nanosilver-impregnated specimens.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100005&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

The objective of this study was to determine the leaching and decay resistance of Alder (Alnus glutinosa) and Scots pine (Pinus sylvestris) wood samples treated with copper based preservatives. Samples were treated with CCA, ACQ, Tanalith E and Wolmanit with different concentrations. Scots pine samples were exposed the mini-block test against brown rot fungi (Poria placenta (Fries) Cook sensu J. Eriksson (FPRL 280)) and Coniophora puteana Karsten (BAM Ebw. 15) while alder wood samples were tested against brown rot fungi (Coniophora puteana) Karsten (BAM Ebw. 15) and white rot fungi (Coriolus versicolor )(CTB 863A). Regarding to leaching test, treated samples were impregnated with 300 ml of distilled water and after 6, 24, 48 and thereafter at 48-hour intervals, the leachate was removed and replaced with fresh distilled water according to AWPA E11. Samples of each leachate were collected and retained for copper analysis. Amount of copper released from treated wood during the leaching test was chemically analyzed with Atomic Absorption spectroscopy. Perchloric acid procedure for the digestion of wood was used according to AWPA A7-97. The amount of copper component (Qd), the cumulative quantities leached (Qc) and the average daily fluxes (FLUX) were calculated. Results shows that CCA treated samples release less copper compared to other copper based preservatives used in this study. Highest mass losses were obtained from the leached samples treated with 1% of ACQ-2200 against decay fungi.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100006&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

Para el diseño de estructuras que utilizan como material estructural principal el bambú Guadua angustifolia, es necesario conocer los valores característicos de sus propiedades mecánicas y módulos elásticos. En este artículo se presenta la metodología experimental utilizada para la determinación de los valores característicos de resistencia mecánica a flexión longitudinal, compresión, corte y tracción paralela a la fibra, torsión, y comprensión perpendicular a la fibra y módulos elásticos de la Guadua angustifolia. Se realizaron ensayos en probetas tomadas de la parte inferior, media y superior de culmos de guaduas provenientes de tres departamentos diferentes de Colombia. Se encontraron los valores característicos de la resistencia a compresión, tensión y corte paralelos a la fibra, flexión longitudinal, torsión y compresión perpendicular así como valores de módulo de elasticidad longitudinal y circunferencial.For the design of structures built with bamboo Guadua angustifolia as structural material it is necessary to know the characteristics values of its mechanical properties and elastics modulus. This article shows the experimental methodology used in the determination of characteristics values for bending, compression, shear and tensile parallel to fiber, torsion, compression perpendicular to fiber and elastics modulus for Guadua angustifolia. Tests were performed in samples taken from the bottom, middle and upper parts of culms of bamboos from three different areas of Colombia. Characteristic values of compression, tension and shear parallel to the fiber, bending, torsion and perpendicular compression strengths were found. Also the elastic longitudinal modulus and the circumferential modulus were determined.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100007&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

In this study; bending properties of beech wood (Fagus orientalis) were predicted using stress - wave method and compared with static bending tests. First, lumbers which were different in length and cross section were weighed and dimensions were measured. Then, moisture contents were obtained via moisture meter. By using the density, moisture, and dimensions of the samples in MTG Timber Grader device, dynamic modulus of elasticity values were determined. And then, samples were subjected to 3 point bending test. Modulus of elasticity and bending strengths were calculated using load - deformation curves. Regression models were developed to interpret relationships between dynamic modulus elasticity and bending properties. Results showed that there is a high regression coefficient (0,86) between dynamic modulus of elasticity and static modulus of elasticity. Regression coefficient between dynamic modulus of elasticity and static bending strength was measured as (0,72) and regression coefficient between static modulus of elasticity and static bending strength was measured as (0,74). Results indicate that bending properties of beech wood lumber can be predicted using stress wave method.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100008&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

In this study, we determined the flexural properties and tensile shear strength of five-ply plywood panels produced with eucalyptus (Eucalyptus grandis), beech (Fagus orientalis.), and hybrid poplar (Populus x euramericana) using urea-formaldehyde (UF), melamine-urea-formaldehyde (MUF) and phenol-formaldehyde (PF) adhesives. Flexural properties were tested on both parallel and perpendicular to grain samples. Tensile shear-strength tests were conducted on four glue lines of the plywood panels, and the effects of species of trees, type of adhesives, and direction of load were determined. The results of variance analyses showed that the effects of species of trees, direction of load, and type of adhesive on flexural properties were significant, but it was determined by specific flexural properties that the effect of the type of adhesive was based on the density of the plywood. In addition, as a result of findings, it can be said that specific mechanical properties may be a good predictor for comparative studies.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100009&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

This study deals with the role of hardness and chemical toxicity in the resistance of pinewood to marine borers. Portuguese wood Maritime pine (Pinus pinaster Ait.) was modified with 1,3-dimethylol 4,5-dihydroxy ethylene urea (DMDHEU), methylated methylol melamine (MMF), tetraethoxysilane (TEOS) and two types of wax. In addition, for comparative purposes, different control species, Ipê, Beech and Blue Gum and CCA treated pine were included. All specimens were exposed over 2 years in sea (Porto, north of Portugal). Three inspections were performed after exposure (6, 12 and 24 months). The influence of type and level of modification as well as hardness was evaluated. As results: Specimens modified with resin have shown slight or trace attack by Teredinids in DMDHEU with low level of modification (10% of weight percent gain, WPG); MMF resin with high and low level of modification (25% and 10% of WPG) have shown trace to moderate attack, respectively. With the TEOS and wax impregnated wood which fill the cell lumens no significant difference in marine borers attack was found as compared to unmodified control specimens, despite the increased hardness.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2014000100010&lng=en&nrm=iso&tlng=en 2014/03/15 - 15:39

In this work, the effects of moisture content variations produced by oscillating drying conditions have been studied by means of non-symmetrical drying (flying wood) and loaded drying (3-point bending test). The oscillating conditions are intended to produce a mechano-sorptive creep that is able to reduce drying stresses. However, our experimental data seem to prove that the activation of the mechano-sorptive creep by oscillations of the moisture content is very limited. Besides, the simulations showed that noisy conditions due to the kiln regulation already activate the mechano-sorptive creep, even for non-oscillating conditions, and could confuse the results. Contrary to the experimental observations, the implementation of classical mechano-sorptive models in the drying simulation model is far too optimistic, which means that these models are not suitable when the material is submitted to numerous oscillations.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300002&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

Wild cherry wood (Cerasus avium (L.) Monench) lumber with a nominal thickness of 5 cm from Duzce region in Turkey was dried through conventional kiln drying using two different programs which are unprotective drying schedules, and protective drying schedules. The aim was to obtain the most desirable kiln schedule for keeping the wood quality at an appropriate level up to final moisture content of 12±2% was reached. Intensity of warping (twist, bow, cup, crook) occurrence, superficial, internal and end checks, residual stresses, drying rate, and moisture gradient in the dried woods were measured, and the results were analyzed. The results showed that there was a more homogeneous moisture profile, fewer occurrences of superficial checks, and absence of internal checks in the protective drying schedules due to low warping values compared to the unprotective drying schedules. Therefore, it seems that protective drying schedules might be recommended as optimum program for wild cherry lumber drying at commercial scale from Duzce region.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300003&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

La calidad del corcho es una de las cuestiones más relevantes para el sector corchero. Es un proceso complejo que requiere evaluar múltiples factores y manejar simultáneamente variables cuantitativas y cualitativas, en ocasiones, con un alto grado de subjetividad. Se presentan dos objetivos, en primer lugar establecer la relación entre la calidad comercial del corcho y la porosidad medida mediante análisis de imagen en diferentes etapas de la transformación industrial (planchas, láminas y tapones), y en segundo lugar, evaluar el potencial de la tecnología NIRS como método de caracterización de la porosidad y, por tanto, de la calidad industrial. Para ello se ha utilizado un colectivo muestral formado por 479 planchas, 176 láminas y 90 tapones de corcho natural de una pieza, clasificados industrialmente en 4, 2 y 3 clases de calidad, respectivamente. El coeficiente de porosidad se evaluó aplicando técnicas de análisis de imagen, en dos y tres clases de color. Los espectros NIRS se obtuvieron en la sección transversal (planchas y tapones), en la sección tangencial (láminas y tapones) y en la sección radial (tapones), con un espectrofotómetro Foss NIRSystems 6500 SY II, mediante la modalidad de reflectancia remota. El análisis estadístico de la relación entre calidad y coeficiente de porosidad, medido mediante análisis de imagen, permite discriminar dos clases de calidad para planchas y láminas y tres clases para tapones. La clasificación de la imagen en un mayor número de cluster mejora los resultados. Las mejores calibraciones NIRS se obtuvieron para la porosidad medida en 3 clases de color, coincidiendo con los resultados obtenidos mediante análisis de imagen y permiten discriminar dos clases de calidad en planchas (refugo y corcho taponable), las dos clases en láminas (R²=0,83; r² =0,78) y las tres clases en tapones (R²=0,67; r²=0,53). Debido a las dificultades de automatización del análisis de imagen en las primeras etapas de la transformación industrial, la tecnología NIRS podría ser una herramienta objetiva que permitiera evaluar la porosidad y diferenciar dos clases de calidad en planchas y láminas y tres clases en tapones.The quality of cork is one of the most important issues for the cork industry. It is a complex process that requires evaluating many factors and simultaneously handles continuous and discrete variables, sometimes with a high degree of subjectivity. There are two objectives, in first place to establish the relationship between the commercial quality of the cork and the porosity measured by image analysis at different stages of industrial processing (planks, sheets, and stoppers), and in second place, to evaluate the potential of NIRS technology as a method of assessing the porosity and, therefore, the industrial quality. For this, there has been used a sample group formed by 479 planks, 176 sheets and 90 one piece natural cork stoppers, classified industrially into 4, 2 and 3 quality classes, respectively. The coefficient of porosity was evaluated into two and three classes of color by using image analysis techniques. NIRS spectra were obtained in the transverse section (planks and stoppers), in the tangential section (sheets and stoppers) and in the radial section (stoppers), with a spectrophotometer Foss NIRSystems 6500 SY II, by remote reflectance mode. Statistical analysis of the relationship between quality and coefficient of porosity, measured by image analysis, discriminates two quality classes for planks and sheets, and three classes for stoppers. Classifying the image into a larger number of clusters improves the results. Best NIRS calibrations were obtained measuring the porosity into 3 classes of color, matching the results obtained by image analysis. This allow to discriminate two quality classes in planks (refuse and race), the two classes in sheets (R²=0.83; r² =0.78) and the three classes for stoppers (R²=0.67; r²=0.53). Due to the difficulties of automated image analysis in the early stages of industrial processing, NIRS technology could be an objective tool to evaluate the porosity and to differentiate two classes of quality in planks and sheets, and three classes in stoppers.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300004&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

El carbón vegetal es un insumo energético muy utilizado en diversos segmentos de la industria siderúrgica, metalúrgica, cimientos y otras, presentando importancia económica e histórica en Brasil. Una de las formas de determinar la procedencia del carbón vegetal es identificando este material, lo que permite comprobar la legalidad de explotación, y cual es su posible origen. Este trabajo tuvo como objetivo describir la anatomía de la madera y del carbón de Pouteria macrophylla (A.DC.) Eyma. y Micropholis guianensis (A.DC) Pierre, y comparar las características antes y después del proceso de carbonización, con la finalidad de suministrar más información sobre la estructura de estos materiales. Los cuerpos de prueba se carbonizaron en horno de mufla, a temperatura máxima de 450 ºC durante un período de aproximadamente 6 horas y 30 minutos. La elevada contracción de las células de Pouteria macrophylla y Micropholis guianensis durante el proceso de carbonización causó alteraciones dimensionales, que no perjudicaron el aspecto cualitativo de las características anatómicas, siendo posible la distinción de especies, e identificación del leño carbonizado a través de la descripción de la madera.Charcoal is an energetic input much applied in different segments of ironwork, metallurgic, cement industry and others, being important economically and historically in Brazil. One manner of determine the precedence of wood coal is the material identification, what allow to probe the legality of exploration and which is its possible origin. This paper aims to describe wood and charcoal anatomy of Pouteria macrophylla (A.DC.) Eyma. and Micropholis guianensis (A.DC) Pierre, and compare the characteristics before and after carbonization process, for the purpose of increase the information about this materials. The samples were carbonized on electric muffle furnace, with maximum temperature of 450 ºC, in approximately 6 hours and 30 minutes. The elevate contraction of cells of Pouteria macrophylla and Micropholis guianensis during carbonization process result in dimensional changes, but it not affect qualitative aspects of anatomical characteristics, being possible the distinction of species and identification of charcoal by wood description.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300005&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

Polipropileno reciclado (rPP) proveniente de rafia sintética de grandes sacos postconsumo, fueron reforzados con 50 y 60% de harina de madera de Pinus radiata de dos tamaños de partícula (60 y 100 mesh) a través de un proceso de mezclado en fundido, con y sin polipropileno maleado (MAPP), utilizado como agente acoplante. La procesabilidad de rPP y de compositos a base de madera-rPP fue estudiada en términos del torque del proceso de mezcla, al igual que las propiedades físicas, térmicas y mecánicas, y comparadas con polipropileno virgen (PP). Los resultados mostraron que la resistencia a la tracción y a la flexión (MOR), módulos determinados en tracción y en flexión (MOE) y resistencia al impacto de rPP y de los compositos madera-rPP, no decrecen comparadas con PP virgen y en términos de los módulos de elasticidad (MOE) y resistencia al impacto son significativamente superiores. Las propiedades mecánicas de las mezclas mejoraron levemente con la presencia de MAPP pero el tamaño de partícula y el contenido de harina de madera (50 y 60%), no tuvieron una clara influencia en estas propiedades. Calorimetría diferencial de barrido (DSC) fue utilizada para estudiar las propiedades de cristalización y fusión de las muestras y los resultados fueron comparados con PP virgen. Los resultados indican que la harina de madera actúa como un agente de nucleación incrementando la velocidad de cristalización, disminuyendo el grado de cristalización y en consecuencia disminuyendo ligeramente el punto de fusión de los compositos madera-rPP. El análisis termogravimétrico (TGA), mostró que la estabilidad térmica de rPP y de los compositos madera-rPP fue ligeramente superior a la de PP virgen. En general, los resultados de este estudio muestran que es factible obtener materiales compuestos de buenas propiedades térmicas y mecánicas utilizando rPP postconsumo reforzado con harina de madera, en proporciones de 50 o 60% de contenido.Recycled polypropylene (rPP) from synthetic raffia big bags was reinforced with 50 and 60% of Pinus radiata wood flour of two particle size (60 and 100 mesh) through a blending process with and without maleated polypropylene (MAPP), used as a coupling agent. The processability of the pure rPP and wood-rPP composites was studied in terms of the mixing process torque and also the physico-mechanical properties and then compared with a commercial virgin polypropylene (PP). The results showed that the tensile and flexural strength (MOR), tensile and flexural modulus (MOE) and impact strength of the pure and reinforced rPP, did not decrease in comparison with the virgin PP, and in terms of the elasticity modulus (MOE) and impact strength, the rPP composites were superior to the virgin plastic. The mechanical properties were slightly enhanced by the MAPP, but the particle size and the filler content (50 and 60%) had no clear influence on the mechanical properties. Differential scanning calorimetry (DSC) was used to study the crystallization and melting behaviour of the rPP and rPP-wood composites and the results were compared with the virgin PP. The DSC analysis indicated that the wood flour particles acted as a nucleating agent, increasing crystallization rate and decreasing the crystallinity degree, and consequently, decreasing slightly the melting temperature of the rPP/wood composites. Thermogravimetric analysis (TGA) revealed that the thermal stability of the rPP and rPP/wood composites were slightly greater than that of the virgin PP. In general, the results of this study showed that it is feasible to obtain composite materials with good thermal and mechanical properties with recycled PP from postconsumer synthetic raffia reinforced with 50 or 60% wood flour.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300006&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

El propósito de este trabajo fue determinar el efecto de un tratamiento térmico, en una atmósfera saturada de vapor de agua, en partículas de madera de la especie Laureliopsis philippiana Losser. Las partículas fueron tratadas en autoclave a 150 ºC por 90 minutos y a una presión de 430 kPa, la cual se generó durante el proceso por la evaporación del agua en el autoclave herméticamente cerrado. Se determinaron la cantidad de extraíbles en soda, etanol tolueno, agua caliente y fría, así también, los porcentaje de celulosa, holocelulosa y lignina, el valor pH, los porcentajes de ácidos volátiles y solubles en agua, y la capacidad tampón, tanto para partículas sin tratamiento como con tratamiento. Para las partículas con tratamiento térmico, se encontró un aumento en el porcentaje de extraíbles, de celulosa, y de ácidos volátiles y lavables, así como también, un aumento de la acidez y de una mayor capacidad tampón, en comparación con las partículas sin tratamiento. El tratamiento térmico produjo un cambio de color en las partículas y una reducción de la humectabilidad. Debido a los cambios químicos encontrados en las partículas tratadas, estas presentarían ventajas en la fabricación de tableros de partículas, favoreciendo el fraguado de la ureaformaldehído.The purpose of this work was to determine the effect of a thermal treatment in a vapor water saturated atmosphere, on wood particles of Laureliopsis philippiana Losser. The particles in autoclave at 150 ºC for 90 minutes and with a pressure of 430 kPa were thermally treated, the pressure generated by the evaporation of water in the sealed autoclave. The amount of extractives in soda, ethanol-toluene, cold and hot water, as well as, the percentages of cellulose, holocellulose and lignin, the pH value, the percentages of volatiles and washables acids, and buffer capacity, for both particles without and with treatment, were determined. In thermally treated particles an increase in the percentage of extractives, cellulose and volatiles and water soluble acids was found, as well as, in thermally treated particles an increment of acidity and a higher buffer capacity was found, in comparison with the particles without treatment. The thermal treatment produced a color change in the particles and a reduction in their wettability. Due to the chemical changes found in the treated particles they could present advantages in the particleboard production, allowing a better ureaformaldehyde polymerization.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300007&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

Proposed is a method to investigate degradation of lignocelluloses by pure cultures of basidiomycetes using preserving jars with vermiculite as reservoir for water and nutrients. Bamboo samples of Gigantochloa atroviolacea and Phyllostachys pubescens and wood samples of Fagus sylvatica and Pinus sylvestris were inoculated with the brown-rot fungus Coniophora puteana and the white-rot fungus Schizophyllum commune. The fungi were cultured on vermiculite containing different amounts of tap water or malt extract solution. Mass loss of the bamboos after 32 weeks was low and did not show a remarkable influence of moisture content and nutrient addition. However, considerable degradation of Pinus sylvestris sapwood occurred by C. puteana whereby moisture and nutrients influenced aggressiveness.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300008&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38

The popularity and demand for wood plastic composites (WPC) has focused research on fiber properties associated with performance. In this study, maple wood fibers (WF) were ball milled and classified into discrete size fractions. Fiber analyses showed only three distinct WF size classes (80-100, 100-200 and <200 mesh). High density polyethylene (HDPE) based WPC were made from classified WF (10 to 50%). The effect of WF size, loading, and maleated polyethylene (MAPE) coupling agent on WPC rheological behavior (torque rheometry and melt flow rate (MFR)) and flexural properties were examined. The WPC MFR decreased with wood loading, increased with a reduction in WF size. The modulus of rupture (MOR) was shown to increase with a reduction in WF size and increase with the addition of MAPE. The increase in MOR is likely due to an increase in the interfacial interaction between the polymer and WF. Modulus of elasticity (MOE) was shown to increase with an increase in wood loading and decrease with a decrease in WF size. The toughness of the WPC was shown to increase with a decrease in WF size and increase upon addition of MAPE.

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-221X2013000300009&lng=en&nrm=iso&tlng=en 2013/10/26 - 13:38