ESACB - Comunicações em encontros científicos e técnicos
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- Alternative species for the forest industry as forms of diversify the landscapePublication . Santos, António J.; Simões, Rogério; Pereira, Helena; Anjos, O.Together the forest and industrial activities within the Portuguese forest sector have a great importance in the national economy. The most used wood species in Portugal for industry (wood panel, sawmill, wood crates) are pine and eucalypt, which leads to extreme dependence and competition between the various industries for the same material, and thus unsustainable pressure on these forest resources. This is one of the causes of the decrease of pinewood area in recent years. On the other hand, this dependence leads to extensive areas of forest monocultures and, subsequently, increased risk of the forest fire propagation. This work intends to stimulate the diversification of the wood products used in the national industry of pulp and to provide a pulp with appropriate characteristics for incorporation as fibber for paper reinforcement. At the level of forest producers, the use of this prime-material would increase competitiveness among tree species and revitalization of less favoured rural areas and, turning them into a possible solution for the lack of wood and an incentive to the reforestation of these areas. Wood from species Cupressus sempervirens and Cupressus arizonica, Acacia delbata and Acacia melanoxylon were analysed. Content of extractives and of Klason lignin, fibre length and coarseness were determined. Representative wood samples from Pinus pinaster grown in Portugal and from Pinus sylvestris grown in Finland were used as reference. The wood from Cupressus sempervirens showed lower Klason lignin and a fibre quality that appears to be more adequate to pulp and paper. Acacia species, with their relatively short, flexible and collapsible fibres, have potential to produce papers with good relationships light scattering/tensile strength and smoothness/tensile strength, at low energy consumption in refining. The studied acacia species showed slightly better performance in pulping than the Eucalyptus globulus sample used as a comparison.
- Principal component analysis as a tool to correlate properties of different laboratorial papersPublication . Santos, António J.; Simões, Rogério; Anjos, O.We measured fibre morphological properties and corresponding handsheet paper properties in pulps obtained from Eucalyptus globulus, Acacia dealbata and Acacia melanoxylon wood samples. The three wood samples were chipped, cooked, and bleached according to standard procedures. The basic chip densities of the samples obtained from the three species studied were 0.351g/cm3, 0.387g/cm3 and 0.536g/cm3, respectively for A. dealbata, A. melanoxylon and E. globulus. All species were submitted to cooking with the following reaction conditions: active alkali charge = 22% (as NaOH); sulfidity index = 30%; liquor/wood ratio = 4/1; time to temperature = 90 min; time at temperature (160 ºC) = 120 min. Acacia species show higher pulp yield than the E. globulus sample used as a reference and cooking selectivity is higher in the Acacia species investigated. The three pulps were beaten in a PFI mill at 500, 2500 and 4500 revolutions under a refining intensity of 3.33 N/mm, and laboratory paper sheets were produced, including the unbeaten pulps, which made up 4 samples per species. The corresponding fibre characteristics in suspension were also determined. We used principal components analysis to investigate the differences in fibre characteristics and paper properties, as well as their interaction. Each value of these variables represents a mean of 10 tests, for the paper sheets. This methodology allowed us to determine how close, or how independent, the study variables were. We conclude there is a group of paper characteristics which depend strongly on each other - paper density, smoothness, tensile index, stretch, burst index, Schopper Riegler degree, internal cohesion and WRV – and are negatively correlated with the light scattering coefficient, opacity and brightness. On the other hand, intrinsic paper fibre resistance is strongly affected by fibre length and coarseness. On the basis of the properties we studied, it is clear that paper produced from Eucalyptus fibre has different properties from that produced from Acacia fibre. Papers produced from both species of Acacia are similar.