Departamento de Engenharia de Madeiras (DEM)
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- Agro-industrial wastes as building insulation materials: A review and challenges for Euro-Mediterranean countriesPublication . Cintura, Eleonora; Nunes, Lina; Esteves, Bruno; Faria, PaulinaThis study investigates the possibility of using agro-industrial wastes for building products, mainly focusing on their insulation properties. A classification of bio-wastes is provided, namely of the lignocellulosic ones and their features and properties are described. Information about three main topics is collected: world production and consumption of some crops already used as building materials, their chemical composition and their most studied properties. Since the considered materials are lignocellulosic and they have many common features, a com- parison is made. The aim is to have comparable information to support future research related to the production of eco-efficient indoor insulation boards. The result of this research is the choice of four different agro-industrial wastes produced in the Euro-Mediterranean Countries. This area was chosen as buildings typically have little or no insulation due to the regional mild climate; however, particularly with climate change, indoor hygrothermal comfort is poor. The collection of information allows some conclusions to be reached about the different bio- wastes already studied and identify gaps in the literature.
- Análise agroecológica de caroços de cereja liquefeitos utilizando FTIR-ATRPublication . Dulyanska, Y.; Esteves, Bruno; Guiné, Raquel; Ferreira, José; Domingos, Idalina; Lopes, Rogério; Lima, Maria; Correia, Paula; Fragata, Anabela; Ferreira, Manuela; Barroca, Maria João; Silva, Aida; Lopes, Luísa P. CruzA agroecologia, combina princípios ecológicos com práticas agrícolas, tem ganho crescente relevância no desenvolvimento de práticas sustentáveis. Esta área valoriza não apenas a produção eficiente de alimentos, mas também a utilização responsável e inovadora dos resíduos agrícolas. Neste contexto, a análise de produtos derivados de cultivos frutícolas, como a caroço de cereja (Prunus avium L.), mostra ser uma área promissora para a identificação de novas estratégias de valor acrescentado. O presente trabalho teve como objetivo analisar o material liquefeito de caroço de cereja doce (Prunus avium L.) e apresentar novas estratégias de valor acrescentado para as possíveis transformações deste produto. Utilizando a espectroscopia FTIR-ATR, foram investigados tanto o material liquefeito quanto os resíduos sólidos resultantes destas liquefações, além do material original de Prunus avium L. Os resultados obtidos demonstram que o material original e o resíduo sólido liquefeito apresentam espectros semelhantes, enquanto as principais diferenças foram observadas entre o material original e o material liquefeito. Estas diferenças indicam potenciais caminhos para o aproveitamento eficiente e sustentável dos resíduos, promovendo a valorização de subprodutos agrícolas e contribuindo para um modelo de produção mais ecológico e economicamente viável. Desta forma, este estudo insere-se na linha de pesquisas que visam fortalecer a sustentabilidade na agricultura, através da inovação e da otimização dos resíduos agrícolas.
- Artificial Weathering of Heat-treated Pines from the Iberian PeninsulaPublication . Esteves, Bruno; Herrera, René; Santos, Jorge; Carvalho, Luisa; Nunes, Lina; Ferreira, José; Domingos, Idalina; Cruz-Lopes, LuísaSamples from the two most common pines grown in Portugal (Pinus pinaster Ait) and Spain (Pinus radiata, D. Don) were heat-treated in industrial facilities in accordance with ThermoWood ® class D. For both species, the variation in surface properties, of untreated and heat-treated wood after artificial weathering from 75 to 750 h, is presented. The analysis included the determination of color, roughness, gloss, and wettability before exposure and after each artificial weathering period. Untreated woods became darker faster, while in heat-treated woods, lightness remained approximately constant until 750 h of artificial weathering. Both untreated and heat-treated wood became more reddish in the beginning of the weathering process, turning greener for longer exposure times. Untreated woods became yellower in the beginning, turning into blueish tones later. Heat-treated wood turned slightly yellower until 750 h of weathering. Gloss decreased for untreated wood with no significant changes in heat-treated wood. Despite the changes, the gloss of both untreated and heat-treated wood converged to similar values. Roughness increased for both untreated and heat-treated woods. Artificial weathering increased the wettability of heat-treated wood.
- Assessing wood quality by spatial variability of transverse elastic properties within the stem: case study on P. pinaster at the meso scalePublication . Pereira, João; Xavier, José; Lousada, José; Silva, AbilioIn this work the radial and longitudinal variations of maritime pine (Pinus pinaster Ait.) transverse elastic properties, within the stem, were investigated. Ring-oriented tensile tests through five radial positions and three height levels were carried out in 750 radial-tangential specimens, at the growth ring scale (meso scale). The strain fields over the gauge section were measured by digital image correlation. A balance between accuracy and spatial resolution was found out in order to assess the gradient strain fields generated by the material heterogeneous mesostructure. A segmentation technique based on image processing and analysis was implemented in order to split each annual ring, at the region of interest, in three main tissues: resin ducts, earlywood (EW) and latewood (LW). Accordingly, transverse elastic moduli of each EW and LW layers were then estimated by two different identification methods: the Anisotropic based method (AbM) and the Virtual fields method (VFM). The VFM was applied to directly identify in-situ Q11 and Q66 stiffness components associated to EW and LW and the AbM was applied to the global ER and GRT evaluation. These effective mechanical properties were used to infer the local ones as a function of mean density, combining the application of a micromechanical model (mixture law) and a unit cell model. The Q11 and Q66 LW/EW ratios were found in the order of 1.32 and 2.45, respectively. These ratios suggest a linear relationship between elastic properties and density. Furthermore, the spatial variability of the elastic properties was analyzed and related to the mesostrucutre heterogeneity, which was given namely by means of density measurements that were taken by x-ray microdensitometry. The results were found in good agreement, presenting significant correlations with density. Specifically, both effective ER and GRT were most often up to approximately 90% determined by mean density.
- Avaliação da cura das resinas dos papéis impregnados de segunda geraçãoPublication . Almeida, Margarida Sofia Marques Lopes de; Carvalho, Luísa Hora; Martins, Jorge Manuel Santos Silva; Mena, Pedro CarteadoA produção de laminados de alta pressão (HPL) tem aumentado largamente devido à sua versatilidade de utilização, elevada resistência e baixo custo. Os laminados podem ser utilizados em diversas aplicações verticais e horizontais, tais como decoração de interior, pavimentos e em diversos tipos de mobiliário. Devido ao grande interesse neste tipo de produtos, a preocupação com a cura das resinas dos papéis que os constituem é constante. Este projecto tem como objectivo a avaliação da cura das resinas dos papéis constituintes de um painel de laminados de alta pressão. Recorrendo a um equipamento de avaliação automática de colagem (ABES – Automated Bonding Evaluation System) foi realizado um estudo sobre o desempenho da ligação de papéis impregnados resultante da cura da resina. Foram estudados diferentes tipos de papéis – dois tipos de papel Kraft; quatro diferentes tipos de papel Decorativo; e quatro diferentes papéis Overlay. Foram testadas diversas configurações de formação dos provetes de ensaio, para garantir uma maior fidelidade à formação de um painel de laminado em condições industriais. Realizaram-se ainda estudos da rugosidade dos papéis para verificar, se a distribuição da resina utilizada na impregnação destes iria influenciar a consolidação do laminado de alta pressão.
- Avaliação de impacte ambiental da gestão de resíduos da produção de uma bancada com base na abordagem de ACVPublication . Silva, Luiza; Ferreira Silva, Maria Elisabete; Brás, Isabel; Domingos, Idalina; Ferreira Wessel, Dulcineia; Ferreira, JoséIntroduction: Consumerism has led to an increase in environmental problems, and for this reason, sustainable solutions must be the priority when designing new products or services. Life Cycle Assessment (LCA) is one of the most important analytical tools available for choosing the best decision when it comes to sustainability. Objective: The focus of this study was to apply an LCA to the management of wastes from a kitchen/bathroom countertop production. The waste management scenarios studied were landfill (current practice) and waste recycling. The panel consists of a ceramic layer on a lamellar panel substrate, formed by glassliner and PVC, which is intended to be resistant to water, scratches and impacts. The residues generated from the panel production are glassliner and PVC plastics and ceramics. Methods: The LCA methodology was followed and the EPD 2018 method available in the SimaPro software was chosen to quantify the environmental impacts of waste management. The environmental impact categories studied were eutrophication, global warming, photochemical oxidation, ozone layer depletion, abiotic depletion and acidification. Results: The results showed that the two plastic wastes are the main contributors to acidification, eutrophication and global warming. However, for photochemical oxidation and water scarcity, the ceramic component residue is the main contributor. Comparing the two scenarios, waste recycling reduces the impacts in all environmental impact categories, in comparison with landfill. Conclusion: Recycling the residues from the production of panels brings improvements in environmental impacts in all categories analyzed.
- Avaliação do ciclo de vida - resenha histórica e perspetiva futuraPublication . Ferreira, José; Esteves, Bruno; Cruz-Lopes, Luísa; Domingos, IdalinaIntroduction: This article presents a historical review and future perspective of life cycle assessment (LCA), as a tool for environmental assessment of products. The first LCA studies, called REPA (Resource and Environmental Profile Analysis), were carried out in the United States of America (USA) in the early 70s of the last century and had as main motivation the aspects related to the environmental implications and the consumption of resources used in the packaging production. It was not until the mid-1980s that these studies began to be carried out in Europe through the Swiss Federal Laboratory for Testing and Investigating Materials (EMPA). Development: In the 90's there was a notable growth in LCA activities in Europe and the USA, namely in terms of harmonization of LCA methods and standardization activities carried out, respectively, by SETAC (Society of Environmental Toxicology and Chemistry) and ISO (International Organization for Standardization). As of the year 2000, countless international and regional organizations were created, with the objective of improving the credibility; acceptance and practice of LCA, as well as many computer tools (software and databases) were developed to support LCA studies. Conclusions: One of the main future challenges for LCA is its greater integration with other life cycle approaches, which have been emerged, as LCA studies have been increasingly well developed.
- Calorific Power Improvement of Wood by Heat Treatment and Its Relation to Chemical CompositionPublication . Domingos, Idalina; Ayata, Umit; Ferreira, José; Cruz-Lopes, Luísa; Sen, Ali; Sahin, Sirri; Esteves, BrunoChemical composition influences the calorific power of wood, mainly due to the calorific power of structural compounds and extractives. Heat treatment changes the chemical composition of treated wood. This work studies the relationship between chemical composition and calorific power improvement by heat treatment. Samples were heat-treated by the ThermoWood process ® for 1 h and 2 h. High heating value (HHV) and chemical composition; lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol, and water were determined. The HHV of untreated wood ranged between 18.54–19.92 MJ/kg and increased with heat treatment for all the tested species. A positive linear correlation was found between HHV and Klason lignin (R2 = 0.60). A negative trend was observed for holocellulose, cellulose, and hemicelluloses content against HHV, but with low determination coefficients for linear regression. The best adjust for polysaccharides was found for hemicelluloses content. A positive correlation could be found for dichloromethane extractives (R2 = 0.04). The same was obtained in relation to ethanol extractives with R2 = 0.20. For water and total extractives, no clear positive or negative trends could be achieved. The results showed that the HHV of wood increased with heat treatment and that this increase was mainly due to the increase in lignin content.
- Changes in the content and composition of the extractives in thermally modified tropical hardwoodsPublication . Esteves, Bruno; Ayata, Umit; Cruz-Lopes, Luísa; Brás, Isabel; Ferreira, José; Domingos, IdalinaChemical composition of wood is known to change during thermal treatments. Two species grown in Turkey, afrormosia (Pericopsis elata) and duka (Tapirira guianensis) were heat treated according to Thermowood® method. Lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol and water were determined. Wood extracts were analysed by gas chromatography with mass detection and existing compounds were identified by NIST17 database. Results show that hemicelluloses and cellulose content decreased for both heat-treated woods along the treatment while lignin percentage increased. The analysis of extractives has shown several compounds normally associated to lignin thermal degradation that increased along the treatment. At the same time several compounds associated to carbohydrate thermal degradation were found in all the extracts for both heat-treated woods. These founding have allowed the understanding of the degradation pattern of wood during thermal modification. There was not much difference between afrormosia and duka woods structural compounds behaviour along thermal modification. However, the variation of the amount of extractives along the treatment depended on the species.
- Chemical changes of heat treated pine and eucalypt wood monitored by FTIRPublication . Esteves, B.; Velez Marques, A.; Domingos, I.; Pereira, H.A hardwood, Eucalyptus globulus Labill., and a softwood Pinus pinaster Aiton., were heat treated at temperatures between 170 and 210ºC in an oven and in an autoclave. The samples were pre-extracted with dichloromethane, ethanol and water and ground prior to Fourier Transform Infrared (FTIR) spectroscopic analysis. The heat treatment caused significant changes in the chemical composition and structure of wood, in lignin and polysaccharides. Hemicelluloses were the first to degrade as proved by the initial decrease of the 1730 cm-1 peak due to the breaking of acetyl groups in xylan. Hardwood lignin changed more than softwood lignin, with a shift of maximum absorption from 1505 cm-1 to approximately 1512 cm-1 due to decrease of methoxyl groups, loss of syringyl units or breaking of aliphatic side-chains. The macromolecular structure becomes more condensed and there is a clear increase of non-conjugated (1740 cm-1) in relation to conjugated groups (1650 cm-1). However, the changes induced by the thermal treatment are difficult to monitor by FTIR spectroscopy due to the different chemical reactions occurring simultaneously.