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Contém referências bibliográficas
Relatório do Trabalho de Fim de Curso de Produção Agrícola.
Relatório do Trabalho de Fim de Curso de Engenharia das Ciências Agrárias – Ramo Agrícola.
Relatório de Estágio do curso de Engenharia de Produção Florestal, apresentado à Escola Superior Agrária do Instituto Politécnico de Castelo Branco.
Introduction: A. melanoxylon wood has a large commercial application given its anatomical characteristics and mechanical properties. However studies on the anatomical characterisation of this species grown in Portugal are scarce.
Objectives: To describe the transverse anatomical characteristics and their within-tree variation of A. melanoxylon trees growing in Portugal.
Methods: 20 trees were analysed in transverse section for tree radial position (10%; 50%; 90%) and five height levels (base, 15%; 35%; 65%; 80%) in north and south directions. Measurements included: fibre diameter (m), fibre wall thickness (m), Runkle index; Flexibility index, vessel number (vessel number /mm2), porosity (%) and vessel width (m).
Results: Earlywood fibres have lower wall thickness and higher lumen diameter than latewood fibres. Runkle and flexibility indexes confirm its potential for pulp and paper production. Porosity was lower near the pith as a result of a slight increase of vessel number with smaller size.
Conclusions: Blackwood showed potential as an alternative species to supply the industry.
The compression properties of cork were studied on samples obtained from cork planks of two commercial quality classes (good and poor quality), with densities ranging from 0.12–0.20g cm-3 and porosities from 0.5 to 22.0%. The stress-strain curves were characterized by an elastic region up to approximately 5% strain, followed by a large plateau up to 60% strain caused by the progressive buckling of cell walls, and a steep stress increase for higher strains corresponding to cell collapse. The direction of compression was a highly significant factor of variation, with cork showing higher strength for the radial compression.
Density influenced compression and cork samples with higher density showed overall larger resistance to compression in the three directions. In the elastic region, an exponential model of Young’s modulus in function of cork density could be adjusted.
The effect of porosity on compression was small and the stress-strain curves were similar regardless of the porosity of the samples, although there was a trend toward an overall increase of stress with porosity for higher strains. Porosity was characterised by a high variability in the anatomical features of the lenticular filling material and the presence of collapsed and thick walled lignified cells. The inclusion of a porosity parameter for the modelling of the elastic modulus did not improve the prediction obtained with density-based models.
There was no significant difference in the compression properties of cork samples obtained from cork planks of good and poor quality classes.
The behaviour of cork under tensile stress in the axial direction was studied for samples taken from cork planks of good (class 1) and poor (class 4) quality grades and at three radial positions within the plank (inner, mid and outer positions). The effect of cork density (ranging from 0.123 to 0.203 g cm−3) and porosity (ranging from 2.8 to 9.6% in the tangential surface) on Young’s modulus and fracture stress and strain was studied. The tensile stress-strain curves of cork showed an elastic deformation up to 2% strain with a Young’s modulus of 30.8 MPa, and a fracture stress of 1.05 MPa at a strain of 7.1% for class 1, and Young’s modulus of 26.1 MPa, and a fracture stress of 0.77 MPa at a strain of 5.5% for class 4. Fracture always started at a pore. The quality class and the radial position in the plank were highly significant factors of the tensile properties variation with good quality cork in the inner part of the plank showing the highest strength. Density influenced the elastic behaviour of cork with a highly significant correlation of increasing E with density, but not so clearly the fracture stress and strain. The variability of tensile properties with porosity was large and although significant, the correlations were lower in spite of a decreasing trend of E with porosity. Fracture depended on the type of defects in cork
Stem and wood characterization of Acacia melanoxylon as an introduced species in Europe
The compression properties of cork were studied for samples of different density. The densities were grouped into three classes: low density (0.13–0.15), mid density (0.15–0.19) and high density (0.19–0.25). The porosity of the cork samples increased from the low to the high density class, with porosity coefficients of 5.1%, 6.9% and 9.4%, respectively. The difference in the porosity was associated with structural features, namely the presence of thick walled cork cells and the presence of lignified cells lining the pores. The stress–strain curves were similar for all cases, showing an elastic compression up to a yield point of about 5% strain, followed by a plateau with a small slope. The cork strength was higher in the radial direction than in the other directions. The density influenced the compression such that the corks with high density presented higher stiffness in compression in three directions: Young’s modulus was 17.4, 22.6 and 26.1 MPa for low, mid and high density corks respectively. This density effect was more evident in the plateau region of the progressive buckling of the cell walls (σ30 was respectively 1.07, 1.29 and 1.54 MPa for the three density classes). The recovery of dimensions after compression in each direction was also studied following compression to 50% strain. The recovery was on average 50% of the initial deformation on the first day, and almost total after 15 days. The recovery was higher for corks with low density and in non-radial directions..
Most 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.
Monofloral Lavandula spp. honey is very appreciated by consumers due to its characteristic and pleas antaroma and flavor. Given the economic importance of this ype of honey, it is important to develop a rapid and nonexpensive methodology that allows certifying its quality. In this context, this study aimed to compare the applicability and accuracy of FTIR-ATR and FT-Raman techniques for the quality evaluation of Lavandula spp. honey.
Calibration models, with PLS regression models, were
obtained for both methodologies concerning the following
parameters: total acidity, reducing sugars, hidroximetilfurfural (HMF), electrical conductivity, ash, proline content, diastase activity, apparent sucrose, total flavonoids,
and total phenolic contents. The calibration models had
high regression coefficients, r
2 (FTIR-ATR: 0.965–0.996;
FT-Raman: 0.983–0.999), high ratios of performance to
deviation, RPD (FTIR-ATR: 5.4–15.7; FT-Raman: 7.6–53.7),
and low root mean square errors (RMSEs; FTIR-ATR:
0.005–3.0; FT-Raman: 0.004–1.02). These results corroborate the potentiality of FTIR-ATR and FT-Raman for quality
evaluation and evaluation of the chemical properties of
Lavandula spp. honey even though FT-Raman technique
provided more accurate models.
