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- Avaliação durabilidade de madeiras termo-modificadas à exposição atmosféricaPublication . Godinho, Delfina; Quilhó, Teresa; Diamantino, Teresa; Gominho, Jorge
- Encouraging Invasive Acacia Control Strategies by Repurposing Their Wood Biomass Waste for Pulp and Paper ProductionPublication . Neiva, Duarte M.; Godinho, Maria C.; Simões, Rogério M. S.; Gominho, JorgeConcerns on the expanding infestation of several Acacia species in the southern Mediter- ranean European countries have triggered an ever-growing requirement for costly targeted control actions. Valorizing biomass waste produced could help promote and better finance these actions. For that purpose, wood wastes from invasive control actions were tested regarding their pulp and paper potential, aiming to entice cellulose industries to partake in future conservation actions. Wood waste from the five most pervasive Acacia species was studied (Acacia dealbata Link, Acacia longifolia Willd, Acacia mearnsii De Wild, Acacia melanoxylon R.Br, and Acacia saligna Labill) regarding physical and chemical characteristics, and a central composite design was used to optimize alkali charge and reaction temperature on pulping yield and delignification. Bleached kraft pulps were produced with each species’ optimized conditions and for an equitable mixture of all species. Optimized pulp yields (52.6%–53.5%) and pulp polymerization degree (2867–3690) of Acacia species were higher than those of Eucalyptus globulus Labill (used as reference). Optimized bleached pulps were refined and fiber, pulp, and handsheet properties determined. Acacia dealbata and A. longifolia presented high specific wood consumption and lower handsheet strength properties, pointing to overall lower pulping potential, while A. melanoxylon and A. mearnsii characteristics were equal to or higher than those of E. globulus. A. saligna pulp and handsheet characteristics appear more suited for tissue paper. The Acacia mixture achieved acceptable characteristics, enabling the indiscriminate use of Acacia wood regardless of the species. As a shortcoming, the Acacia pulps showed the worst optical characteristics, with brightness dropping substantially with beating (64%–76%) when compared to E. globulus (81%).
- Thermally modified wood of Acacia melanoxylon preliminary resultsPublication . Godinho, Delfina; Lourenço, Ana; Araújo, Solange de Oliveira; Quilhó, Teresa; Diamantino, Teresa; Gominho, JorgeDue to the urban development and the continuous growth of cities, architects, engineers, and constructors are choosing sustainable materials. Wood is a natural, sustainable, and low-carbon material. However, wood presents some disadvantages (e.g. hygroscopicity and anisotropy), that can be overcome by thermal treatments [1]. The wood thermal modification only requires temperature and an oxygen-free atmosphere, it does not use any kind of chemical products and improves some wood properties such as dimensional stability, water resistance, and biological attack resistance [1]. Acacia melanoxylon is among the most widespread invasive plants in Europe. Today, Acacias are widely naturalized and have become an environmental problem in Southwestern Europe, particularly in Portugal. Its presence can be a threat to native species and has been declared ‘‘invaders’’ due to its rapid growth rate, prolific production of seeds with high longevity, and germination stimulated by fire. Acacia wood has very interesting mechanical properties which can be used in building construction, façades, walkways, and decks, among others. This study aimed to thermally modify Acacia wood in collaboration with a Portuguese company, Santos & Santos. Then the unmodified (A) and modified (MA) woods were exposed to weathering in two different environments (urban and industrial/maritime) and the color, chemical, and morphological changes were evaluated over time. The wood color was determined by a portable spectrometer measuring the CIELab parameters. The summative chemical analysis (e.g. total extractives and lignin contents) was made and the lignin monomeric composition was accessed by analytical pyrolysis (Py-GC/MS). Additionally, the samples were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The treatment induced a decrease in the soluble lignin content (1.1% for A and 0.70% for MA) and an increase in Klason lignin (17.2% for A and 27.0% for MA), which can be caused by a lignin degradation during the thermal treatment [2]. Py-GC/MS showed a decrease in S/G ratio in modified wood (2.2 vs. 1.7), caused by an increase of G-lignin units and a decrease of S-units in the modified acacia wood. This could be explained by lignin modifications during the treatment [2]. Through SEM/EDS analysis, some cracks in fibers and particles were detected in samples exposed to both environments. Some deposition of dust, aerosols from pollution, and salt particles were found in woods exposed to the industrial/maritime environment. Likewise, woods from the urban environment also had some deposition of dust. The study is still running and for that reason is not possible to present all the results, namely those from the analysis of the weathered samples.
- Potential of Acacia melanoxylon for PulpingPublication . Pereira, Helena; Simões, Rogério; Santos, António; Gominho, Jorge; Lourenço, Ana; Anjos, OféliaMost of the fibre raw materials used by the pulp and paper industry are from a small number of tree species. For instance, Eucalyptus and Pinus species are the major industrial pulpwood sources obtained from forests characterized by a relatively low biodiversity. The large monoculture areas also increase environmental risks such as those related to biotic attacks or forest fires. Diversification of industrial fibre sources has therefore been a matter of research and the characterization of different raw materials has been made in view of their pulping potential. Acacia melanoxylon R. Br. (blackwood) grows well in Portugal in pure or mixed stands with Pinus pinaster Aiton, and is valued as a timber species with potential for sawmills. In addition, the wood anatomical and chemical characteristics also allow to consider the species as an alternative raw material for the pulp industry. Acacia species, with their relatively short, flexible and collapsible fibres, have potential to produce papers with good trade-offs between light scattering/tensile strength and smoothness/tensile strength, at low energy consumption in refining. The pulping and paper making potential of blackwood has been studied by several authors showing an overall good pulping aptitude under the same experimental conditions of kraft pulping as used for eucalypt pulping with pulp yields ranging between 47 and 58 %. The presence of heartwood should be taken into account because it decreases the raw-material quality for pulping due to the higher extractives content. Heartwood proportion should therefore be considered as a quality variable when using A. melanoxylon wood in pulp industries. This chapter describes the characterization of the A. melanoxylon wood pulping performance, regarding yield and kappa number, and the pulp and paper properties. The application of fast spectroscopic technologies for pulp quality determination is also described.