Estudo da aptidão da Acacia melanoxylon R. Br. para a produção de pasta e da aplicação de espectroscopia de infravermelho próximo (original) (raw)
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Variation of wood density and mechanical properties of blackwood (Acacia melanoxylon R. Br.)
2014
The variation of wood density and mechanical properties with site, tree and within tree (longitudinal and radial) were studied for blackwood (Acacia melanoxylon R. Br.) grown in four sites in Portugal. Twenty trees were randomly selected (40 cm dbh class, 33-51 years of age), sampled at three stem height levels (5%, 35% and 65% of tree height) and three radial positions (10%, 50% and 90% of radius). They were further tested for air-dry density at 12% moisture content, bending strength (MOR), modulus of elasticity (MOE) and compression strength parallel to grain (CS), using ISO standards.
Wood and bark fiber characteristics of Acacia melanoxylon and comparison to Eucalyptus globules
CERNE, 2011
Wood and bark fibers of Acacia melanoxylon were characterized and compared to Eucalyptus globulus which is a major quality source of pulp fibers. In 20 trees from four sites, fiber length and wall thickness were measured at 5, 35 and 65% of total tree height and at 10, 30, 50, 70 and 90% of the distance from pith. Maceration were prepared in a 1:1 glacial acetic acid:hydrogen peroxide solution. Wood and bark fiber length varied between 0.90 - 0.96 mm and 1.33 - 1.59 mm respectively. The cell wall thickness varied between 3.45 - 3.89 µm in wood and 5.01 - 5.40 µm in bark. Wood and bark fiber length decreased from the bottom to the top of the tree and cell wall thickness had no specific pattern for axial variation. Fiber length and wall thickness increased from the pith to the bark, but the wall thickness increased slightly with some fluctuations. In Acacia melanoxylon significant site differences were found in relation to bark fiber length and to wood wall thickness. The fibers of Ac...
Forest Systems, 2013
Acacia is a woody genus with more than 1000 species occurring naturally in arid areas of Australia, Asia, Africa, and tropical America (Playford et al., 1991). During the eighteen and nineteen centuries some native acacia from Australia were introduced in several countries, e.g. Acacia mangium Willd was planted in Brazil in order to profit by its fast growth rate and rectilinear stem. Nowadays, several acacia species are exploited worldwide for firewood, pulpwood, tannins and other colouring extractives, carpentry, forage, as well as ornamental trees and sloping banks (Playford et al., 1991). Acacia melanoxylon R. Br. is distributed in Australia along the east coast, from southern Tasmania to Atherton in Queensland, and is a prized native tree for furniture. This acacia, also named Blackwood, has been extensively utilized in South Africa for fuel, shelter belts, fence droppers, building structures and mine props, and high quality Blackwood stems are highly rated for quality sawn products (Playford et al., 1991). In the beginning of the twentieth century various acacia species were introduced in Portugal in order to colonize dry and poor sandy soils along the coast. The country has revealed good ecological conditions for the development of some of them, particularly A. melanoxylon and A. dealbata and, nowadays, there are several spontaneous stands dispersed by natural dissemination in all the territory. So far, because the control of these alien invader species using chemical and mechanical methods has not been done with satisfactory results (Tavares et al., 1999), nowadays Acacia melanoxylon is one of the most disseminated wattle species in north and west of Portugal. Here the national forest inventory count about 4,000 hectares of different acacia species and more 6,300 hectares in Azores and
Influence on pulping yield and pulp properties of wood density of Acacia melanoxylon
Journal of Wood Science, 2012
Wood density and pulp yield are key parameters in the evaluation of tree productivity and quality for pulping and their relationships are of high practical importance. The influence of wood density on pulp yield and other pulp quality parameters was investigated using Acacia melanoxylon and its natural variability as a case study. Twenty trees were harvested (five trees in each of four sites in Portugal), and wood discs taken at different height levels, from the base to the top of the tree, providing 100 wood samples, covering the natural variability of wood density ranging from 449 kg m -3 to 649 kg m -3 . Under the same experimental conditions of kraft pulping, screened pulp yield ranged 47.0-58.2 %, Kappa number 10.9-18.4, ISO brightness 14.9-45.6, fibre length 0.660-0.940 mm and fibre width 16.2-22.9 lm. The pulp yield and Kappa number were not correlated with wood density. Higher pulp yields were associated with lower Kappa numbers and alkali consumption, suggesting the important role of chemical composition of wood on kraft cooking. The results confirm the high pulping potential of Acacia melanoxylon trees grown in Portugal and suggest the possibility of tree selection using both wood density and pulp yield.
Mantanis G., Birbilis D. (2010). Physical and mechanical properties of Athel wood (Tamarix aphylla)
The aim of this work was to determine the main physical and mechanical properties of athel wood (Tamarix aphylla), one of the least studied non-commercial wood species. Wood samples of Tamarix aphylla were harvested from a small tree stand in Molyvos coastal area (Lesvos, Greece) and standard test methods were followed on small green specimens. Athel wood’s air- and oven dry densities were determined at 0.73 and 0.66 g/cm3, while maximum tangential shrinkage and swelling were approximately 10.8 and 12.1%, respectively. The volumetric shrinkage and swelling were estimated at 14.0 and 15.5%, respectively. Modulus of rupture, modulus of elasticity, compression strength parallel to grain and Janka hardness (perpendicular to grain) values were found to be 88.5 N/mm2, 7,533 N/mm2, 40.9 N/mm2 and 33.7 N/mm2, respectively. Keywords: Wood; Tamarix aphylla; Mechanical properties; Density; Shrinkage; Swelling
Variation in wood density and ring width in Acacia melanoxylon at four sites in Portugal
European Journal of Forest Research, 2014
The radial variation in wood density in Acacia melanoxylon R. Br. was studied using microdensitometry by sampling 20 trees with a 40-cm diameter class at four sites in Portugal. The measurements were taken from pith to bark at breast height. A. melanoxylon had an average ring density of 0.607 g cm -3 , ranging from 0.556 to 0.630 g cm -3 . The mean growth was 6.0 mm year -1 . Latewood corresponded, on average, to 34 % of the ring width. Between-tree variability at each site was the main source of variation in the density components, representing between 30 and 54 % of the total variation. Between-sites variability represented from 0 to 21 % of the total variation in density components. The environmental effects (site related) were more pronounced on latewood, while the genetic effect (tree related) was more evident in earlywood. Ring width, latewood percentage and heterogeneity index were independent from site, trees in site and age effects. The values of wood density and radial growth revealed that A. melanoxylon can be important as a commercial timber species in Portugal.
Seasoning of Acacia melanoxylon Lumber Grown in Chencha, Southern Ethiopia
2019
This study investigated the density and seasoning characteristics along with the tree height of Acacia melanoxylon timber. A 30 years-old Acacia melanoxylon trees were selected and harvested from Chencha, Southern Ethiopia. From each tree, three 2.5 m long logs were collected from the bottom, middle and top of the tree height. The logs are sawn and sample boards were prepared for determination of the density and seasoning characteristics along with the tree height. The basic density and tangential, radial and volumetric shrinkage were a significant difference (p<0.05) along with the tree height and the highest values were observed at the base and lowest at the top. The overall mean basic density of the tree was 0.57 g/cm and shrinkage (%) 3 values of the tangential, radial and volumetric shrinkages from green to 12% moisture content (MC) were 3.80%, 1.97% and 6.19%, respectively. While longitudinal shrinkage was negligible. The Lumber seasoning experiments were carried out using ...
WOOD PROPERTY VARIATION IN ACACIA AURICULIFORMIS GROWING IN BANGLADESH
This study examined the radial variations of wood properties in 11-yr-old Acacia auriculiformis grown in Bangladesh having diameters of 222 38 mm. The basic density, fiber length, and fiber length increment increased up to about 80 mm radial distance from the pith and then were almost constant toward the bark. The compressive strength (CS) increased from the pith to 50 mm and then became nearly constant to the bark. Conversely, the specific compressive strength, the ratio of CS to airdried density, was almost constant from pith to bark, indicating positive relationships. However, the airdried density explained only 50% variation of the CS. On the basis of radial variation of basic density, the core wood and outer wood boundary can be delineated at 70 – 90 mm from the pith. Similarly, the fiber length and fiber length increment curves showed that this boundary could be marked at 60 – 90 mm from the pith. The selected wood properties except CS varied significantly among the trees, which indicated the potential of tree selection for wood quality improvement through tree breeding.
Acta Silvatica et Lignaria Hungarica
This paper studied the basic density and mechanical properties differences of wood among and within Sclerocarya birrea and Anogeissus leiocarpus. Three trees from each species were selected from the Lagawa Natural Forest Reserve in Western Kordofan State, Sudan. Test specimens were selected from three vertical positions (10, 50, and 90% along the bole length) of the trees. Specimens were also collected from three horizontal positions (innerwood, middlewood, and outerwood) within each of the three vertical positions. Tests for basic density of wood (BD), modulus of rupture (MOR), modulus of elasticity (MOE), compressive (CS), and shear strength (SS) parallel to the grain were performed. An analysis of variance shows that only the horizontal positions were a significant source of variation for both species studied. The correlation coefficient of BD was significant, weak, and positive for the mechanical properties of A. leiocarpus. A similar observation was found for BD correlated with...