It is equally important as a source of firewood and charcoal, being among the preferred species for charcoal making throughout Southern Africa ( Louppe et al. It is suitable for flooring, joinery, mine props, vehicle bodies, crates, veneer and plywood. angolensis are used for construction, cheap furniture, railway sleepers, utensils and beehives. angolensis wood is very heavy and hard, the heartwood is coloured green-brown and the sapwood is grey-yellow ( Frost 1996, Palgrave 2002). spiciformis is moderately heavy, slightly hard and difficult to be worked, with no significant difference between heartwood and sapwood colours while P. In Angola, this forest occupies an area of 585949 km 2, which corresponds to 47% of the total country area, being considered mainly as a source for timber production ( Figueiredo et al. Keywords: Derived wood properties kraft pulping strength properties wood anatomy wood chemistry.īrachystegia spiciformis and Pericopsis angolensis are two hardwood species from the Miombo woodlands (formation of natural forest, dry and warm predominantly in the South-Central region of Africa). Both species may be suitable for unbleached wrapping papers and rigid cardboards manufacturing. As a conclusion, Brachystegia spiciformis wood has better pulpability than Pericopsis angolensis wood, according to its pulps properties, despite of the similar pulp yield between both species. Brachystegia spiciformis pulps reached tensile, tear and burst indexes of 100,3 Nm g -1 10,7 mN.m 2 g -1 and 6,1 kPa.m 2 g -1, respectively. Pericopsis angolensis pulps reached tensile, tear and burst indexes of 99,6 Nm g -1 5,9 mN.m 2 g -1 and 4,9 kPa.m 2 g -1, respectively. In kraft pulping, a higher demand of active alkali was needed for both species, and pulps with high kappa number (24-27) and low pulp yield (40%) were obtained. Brachystegia spiciformis has a higher cellulose content, lower hemicellulose and lignin content, and higher S/G ratio than Pericopsis angolensis. Runkel ratio, slenderness ratio, and the coefficients of flexibility and rigidity in Brachystegia spiciformis were 1,5 65,7 41,2% and 29,4% while in Pericopsis angolensis these values were 17,6 59,9 5,4% and 47,3%, respectively. Pericopsis angolensis wood has higher cell wall thickness and occluded fibre lumen as remarkable anatomical properties. Brachystegia spiciformis wood density was 640 kg m -3 and Pericopsis angolensis was 795 kg m -3. The wood features, kraft pulping and strength pulp properties of both species were evaluated in order to determine their potential as raw material for papermaking. Brachystegia spiciformis and Pericopsis angolensis are two hardwood species found in the Miombo woodlands.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |