Browsing by Author "Nunes, Lina"
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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.
- 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.
- Comparison between heat treated sapwood and heartwood from Pinus pinasterPublication . Esteves, Bruno; Nunes, Lina; Domingos, Idalina; Pereira, HelenaSapwood and heartwood samples of Pinus pinaster were treated in an oven at 190ºC and 200ºC for 2-6h. Dimensional stability, measured as Anti Shrinking Efficiency (ASE) between 0% and 65% relative humidity, durability against fungi, mechanical resistance (MOE and MOR), hardness and chemical composition were determined for treated and untreated sapwood and heartwood. Radial ASE reached 52% for sapwood and 50% for heartwood while tangential ASE reached 50% and 40% respectively. MOE increased slightly at the beginning of the treatment decreasing afterwards. No significant differences were found between sapwood and heartwood. MOR decreased by 50% and 30% for sapwood and heartwood respectively. A significant increase in durability against Rhodonia placenta was found for both heartwood and sapwood at the higher temperature and for heartwood only at 190º for 4h.
- Densification and heat treatment of maritime pine woodPublication . Esteves, Bruno; Ribeiro, Fábio; Cruz-Lopes, Luísa; Ferreira, José; Domingos, Idalina; Duarte, Marta; Duarte, Sónia; Nunes, LinaPine (Pinus pinaster Ait.) wood samples were subjected to a combined treatment by densification and heat treatment. Samples were densified before and after heat treatment. The heat treatment was made inside an oven at 190ºC during 2 to 6 h and wood densification was made in a hot press at around 48 bar pressure and temperatures between 160ºC and 200ºC for 30 min. Compression-set, compression-set recovery after three cycles of water soaking followed by oven drying, density, hardness, bending strength and stiffness and durability against subterranean termites were determined after the treatment. Results show that densification increases density, hardness, bending strength, stiffness and durability against termites. Heat treatment applied after the densification is more effective in reducing compression-set recovery than if applied before.
- Improvement of termite resistance, dimensional stability and mechanical properties of pine wood by paraffin impregnationPublication . Esteves, Bruno; Nunes, Lina; Domingos, Idalina; Pereira, HelenaParaffin has been used as surface protection of wood throughout the ages but its use for impregnation to improve wood resistance to biodegradation is recent. This study determined the main improvements on wood properties with paraffin impregnation. Healthy Pinus pinaster Ait. wood was impregnated with paraffin at different levels using a hot–cold process. Weight gain, equilibrium moisture content and dimensional stability (ASE) at 35 and 65 % relative humidity, termite durability against Reticulitermes grassei (Clément), bending strength, bending stiffness (MOE) and Janka hardness were determined. Density increased from 0.57 to 0.99, ASE ranged between 38–96 % and 16–71 % for 35 and 65 % relative humidity, respectively. Equilibrium moisture content decreased from 9.9 and 12.0 % to 0.8 and 3.6 % for 35 and 65 % relative humidity. Termite durability improved from level 4 to level 3 of attack, and higher termite mortality was found in treated wood (52 % against 17 %). Bending strength (MOR) increased with paraffin weight gain, reaching a 39 % increase. MOE also increased by about 13 % for wood with a weight gain around 80 %. Janka hardness increased significantly reaching about 40 % for wood with 80 % weight gain. Paraffin impregnated wood has improved properties with regard to equilibrium moisture content, dimensional stability and density, bending strength and Janka hardness, and resistance against termites.
- Optimizing Douglas-fir bark liquefaction in mixtures of glycerol and polyethylene glycol and KOHPublication . Esteves, Bruno; Cruz-Lopes, Luísa; Ferreira, José; Domingos, Idalina; Nunes, Lina; Pereira, HelenaThe outer bark of Douglas-fir (Pseudotsuga menziesii) has a significant amount of cork tissue that may be an important source of chemicals derived from its natural polymers, suberin, cellulose, hemicelluloses and lignin. The present work focuses on the polyalcohol liquefaction of Douglas-fir bark with glycerol and polyethylene glycol (PEG) in order to obtain a liquid that can be further processed to other chemicals and products. The results show that Pseudotsuga bark can be liquefied in a significant percentage in presence of alkali. The best liquefaction yield was obtained with 6% KOH as agents. Although the use of a cosolvent is favorable, good liquefaction yields can also be obtained by glycerol alone. Lower temperatures are favorable as they lead to acceptable liquefaction yields. FTIR-ATR studies showed that all the structural compounds of the bark were attacked and depolymerized. The process tested has a high potential for generation of value-added products from liquefied Douglas-fir bark.
- Proof-of-Principle That Cellular Automata Can Be Used to Predict Infestation Risk by Reticulitermes grassei (Blattodea: Isoptera)Publication . Sequeira, João G. N.; Nobre, Tânia; Duarte, Sónia; Jones, Dennis; Esteves, Bruno; Nunes, LinaOver the past few decades, species distribution modelling has been increasingly used to monitor invasive species. Studies herein propose to use Cellular Automata (CA), not only to model the distribution of a potentially invasive species but also to infer the potential of the method in risk prediction of Reticulitermes grassei infestation. The test area was mainland Portugal, for which an available presence-only dataset was used. This is a typical dataset type, resulting from either distribution studies or infestation reports. Subterranean termite urban distributions in Portugal from 1970 to 2001 were simulated, and the results were compared with known records from both 2001 (the publication date of the distribution models for R. grassei in Portugal) and 2020. The reported model was able to predict the widespread presence of R. grassei, showing its potential as a viable prediction tool for R. grassei infestation risk in wooden structures, providing the collection of appropriate variables. Such a robust simulation tool can prove to be highly valuable in the decisionmaking process concerning pest management.
- Properties of furfurylated wood (Pinus pinaster)Publication . Esteves, Bruno; Nunes, Lina; Pereira, HelenaAbstract Sapwood samples of Pinus pinaster wood were treated with a 70% furfuryl alcohol mixture. Weight percent gain (WPG), equilibrium moisture content, dimensional sta- bility, MOE, bending strength, hardness, density and dura- bility were determined. WPG was on average 38%. Equilibrium moisture con- tent decreased more than 40%. Dimensional stability in- creased reaching an ASE of 45%. MOE was little affected by the treatment but bending strength increased by about 6%. Hardness increased by about 50%, and density by 37%. Mass loss due to Postia placenta and Coniophora puteana decreased by 96% and 86%, respectively. Furfurylation of Pinus pinaster wood shows an interesting potential to im- prove the wood quality for solid timber products.
- State of the art of industrial wood protection in PortugalPublication . Nunes, Lina; Carmo, Júlia; Vicente, José; Esteves, BrunoThis work intended to give a perspective of industrial wood protection in Portugal. A survey was made of the companies treating wood mainly for use classes 3 and 4 such as autoclave treatments with biocides and wood modification procedures. Currently there are 23 companies with 33 production plants with an autoclave installed for wood preservation by impregnation. There are also two companies producing modified wood by thermal treatment. Most of the plants are located in the central and northern regions of Portugal. The leading preservation chemicals used in Portugal are Tanalith E and Celcure brands. The main wood species used in all companies is Pinus pinaster from local producers. The products commercialized by the treating companies are diverse: pre-fabricated houses, garden furniture and playgrounds, decks, poles, stakes, and sawn wood. Modified wood producers sell mostly decks and cladding. Considerable changes are expected in the next few years due to the requirements of European Directives and the typical constraints of the Portuguese market.