Browsing by Author "Labidi, Jalel"
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- Adhesives from liquefied eucalypt bark and branchesPublication . Esteves, Bruno; Cruz-Lopes, Luisa; Fernandes, Ana Paula; Martins, Jorge Manuel; Domingos, Idalina; Ferreira, José; Silva, Silvia Helena Fuentes; Labidi, JalelAdhesives made from lignin are one of the most promising alternatives to common ureaformaldehyde adhesives. One of the possible sources is from wood or bark liquefaction at low temperatures and pressure. The possibility of using forest wastes for the production of adhesives was the objective of this work. Eucalypt bark and branches are wastes produced in the company Pedrosa & Irmãos, which is a forest management company based in Portugal (Leiria). The wastes were liquefied with polyalcohols catalyzed by sulfuric acid. The water insoluble fraction of the liquefied material was used for the production of the bio-adhesive. Both fractions were characterized and the bonding performance of the bio-adhesive was tested by ABES. The bio-adhesives obtained from bark or branches were similar, exhibiting a bonding strength approximately half of the conventional UF resin.
- Energy and environmental profile comparison of TMT production from two different companies - a Spanish/Portuguese case studyPublication . Ferreira, José; Herrera, René; Labidi, Jalel; Esteves, Bruno; Domingos, IdalinaLife Cycle Assessment (LCA) is a technique for assessing the environmental aspects and potential impacts associated with a product and has been increasingly used to identify processes or stages in the wood chain with a high environmental impact or to highlight areas where environmental information is unknown. The main aim of this study was to quantify and compare the environmental impacts and the energy used for the production of one cubic meter of Thermally Modified Timber (TMT) by two different companies, one in Spain and the other in Portugal, using the LCA methodology. The LCA study was developed based on ISO 14040/44 standards. The inventory analysis and, subsequently, the impact analysis were performed using the LCA software SimaPro8.1.0.60. The method chosen for the environmental impact assessment was ReCiPe, and for energy use the Cumulative Energy Demand method was chosen. The results show that to produce 1 m3 of thermally modified pine timber the Portuguese company used 14.38 GJ of cumulative energy demand, of which 1.92 GJ was nonrenewable and 12.46 GJ renewable, and the Spanish company used a total of 17.55 GJ, of which 2.52 GJ was nonrenewable and 15.03 GJ renewable. The thermally modified pine timber produced by the Spanish company presented the best environmental results for 13 impact categories in comparison to the 5 best environmental results presented by the Portuguese company. From the weighting triangle, we can conclude that the Portuguese pine boards have a lower environmental impact than Spanish pine boards if a high weight (> 40%) is given to resources, while a weight of <80% is given to human health; otherwise the opposite is true. Regardless of the company, the energy used in the thermal treatment process was identified as the main factor responsible for climate change, acidification, eutrophication, photochemical oxidant formation, metal depletion and fossil depletion. This has to be expected as the treatment is based on heat production and no chemicals are added during the heat treatment process. The round wood production was identified as the leading process responsible for ozone depletion and also presented remarkable contributions to eutrophication and photochemical oxidant formation.
- Synthesis, characterisation, and thermal degradation kinetics of lignin-based polyurethane wood adhesivesPublication . Hernández-Ramos, Fabio; Esteves, Bruno; Carvalho, Luisa Hora de; Labidi, Jalel; Erdocia, XabierPolyurethane adhesives are widely employed in a range of industrial applications due to their exceptional bonding strength, flexibility, and chemical resistance. These materials play a crucial role in wood bonding technologies, where their versatility and durability make them ideal for creating strong, long-lasting joints. In this work, Four different polyurethane wood adhesives were synthesised using ligno-based bio-polyols obtained through microwave assisted liquefaction reaction of two wood species (hardwood and softwood) using polyethylene glycol and glycerol as solvents. The reaction conditions used for the synthesis of bio-polyols were optimised in a previous work. The synthesis of polyurethanes was carried out by one-shot method using Tetrahydrofuran (THF) as solvent and MDI as diisocyanate employing different NCO:OH ratios (2.0:1, 2.5:1, and 3.0:1). The chemical structure of polyurethanes was determined through ATR-FTIR and the shear strength was analysed using Automated Bonding Evaluation System (ABES) employing beech veneer strips. Through ABES it was concluded that an NCO:OH ratio of 2.5:1 was the formulation that showed the best shear strength for a pressing time of 120 s. Employing this ratio and the same synthesis procedure, two new polyurethanes were synthesised with the bio-polyols obtained using crude glycerol instead commercial glycerol. Finally, a study of thermal degradation kinetics employing the Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) isoconversional methods of the polyurethanes synthesised with an NCO:OH ratio of 2.5:1 was carried out. On the one hand, the Ea of each system were estimated for the different α ratios, obtaining slightly higher values for the adhesives produced using commercial glycerol than crude glycerol. In addition, the pre-exponential factor was determined, enabling an estimation of the lifetime of the polymers. This study highlights demonstrated that crude glycerol could replace commercial glycerol without compromising adhesive properties. The findings revealed that the lignin source significantly influences the adhesive's characteristics and stability, while addressing challenges in achieving industrial viability remains essential for broader application.