Comparison of teak wood properties according to forest management: short versus long rotation

Key message: Teak (Tectona grandis L.f.) is one of the most important tropical hardwood tree species, which is widely planted in Indonesia. Wood properties are strongly influenced by forest management conditioning further utilization of wood. Context: In Indonesia, teak wood has been supplied from the state forests (Perhutani) for long rotation teak and from community teak plantations for short rotation teak. Short rotation teak has been harvested at 7–10 years and long rotation teak at 40–60 years. Aims: This paper discusses the characterization of technical properties of short and long rotation teak wood based on the chemical, anatomical, physical, and mechanical properties. Methods: The properties of short rotation and long rotation teak woods were characterized by measuring their density, extractive contents, chemical composition, swelling, wettability, water sorption isotherm, decay resistance, anatomical properties, bending strength (modulus of rupture (MOR), modulus of elasticity (MOE)), and hardness. Results: The results indicate that short rotation teak was not particularly different in swelling, MOE and MOR, and Brinell hardness compared to long rotation teak, although it was less dense and less durable due to lower heartwood and extractive contents. Therefore, careful attention should be given to the use of short rotation teak in some wood-processing technologies. Conclusion: Lower wood density and durability of the short rotation compared to the long rotation teak will restrict its utilization to some extent for both indoor and outdoor applications. Fast-growing teak from community cannot be used as usual heartwood teak from Perhutani because of the very low proportion of useful heartwood in the stem

Characterization of thermally modified short and long rotation teaks and the effects on coatings performance

Many wood processing industries use short rotation teak, which has lower quality especially in durability and dimensional stability. Heat treatment is an eco-friendly method to improve dimensional stability and durability of wood. The objectives of the study were to investigate the effects of thermal modification on chemical composition, colour, dimensional stability and durability as well as coating’s performance after accelerated weathering of short and long rotation teak for exterior utilization. In this study, the samples were heated in oven at 220 °C for 20 h under nitrogen atmosphere. Results showed that independently of growth conditions teak woods underwent hemicelluloses degradation and an increase of lignin content after heat treatment. Extractives contents were lower in short rotation than in long rotation teak, and decreased in all cases after heat treatments. Dimensional stability was considerably improved as indicated by anti-swelling efficiency values of 64.9% and 58.9% for short and long rotation teak, respectively. Heated teak woods were more resistant against Trametes versicolor and the durability of short-rotation teak increased from moderate to very durable. Coatings on heat treated teaks had better bonding quality and better photo-stability when compared to unheated. Heated short rotation teak could be considered for exterior application

Etude de systèmes de finitions pour bois (application de nouvelles formulations, vieillissement et amélioration des performances)

L origine naturelle du bois génère des difficultés quant à la durabilité de la finition. Ces difficultés sont liées à son anatomie et aux substances extractibles qu il contient. La première partie de ce travail étudie les finitions photosensibles utilisées en menuiserie industrielle pour leurs avantages notamment, la limitation des émissions de COV. Nous avons suivi par photocalorimétrie la réticulation de résines acryliques sous irradiation monochromatique à 366, 420, 440 et 450 nm, avec filtre à 450 nm et en toute lampe. Les résultats obtenus montrent la possibilité de réticuler des finitions photosensibles par la lumière du soleil grâce à l utilisation de systèmes photoamorceurs puissants dits de seconde génération. L influence des absorbeurs UV sur la réticulation amorcée par ce système est également abordée. Les performances des systèmes de finition ainsi obtenus ont été évaluées par un vieillissement accéléré au QUV. La deuxième partie est une étude exploratoire dont l objectif est le développement d un anti-UV minéral nanodispersé de deuxième génération de composition et de morphologie optimisées pour une application spécifique d absorbeur UV. Nous avons testé trois produits: CUB, HTB et RNE. Au cours d un vieillissement extérieur au QUV, les performances de ces absorbeurs se sont révélées encore insuffisantes.The durability of a finish applied onto wood is generally affected by the natural origin of the material and merely by its anatomy and the presence of extractives. In the first part of this work, the photocurable finishes used in industrial joinery were studied because of their advantages and especially the reduction of Volatile Organic Compounds (VOC). The reaction of polymerization of acrylic resins was investigated using photocalorimetry under monochromatic radiation at 366, 420, 440 and 450 nm, with a filter at 450 nm and with the overall light spectrum. The results obtained show that solar light allows the curing reaction if some improved photoinitiators are used (2nd generation photoinitiators). The influence of UV absorbers -on the polymerization initiated by these products- was also studied. The performances of complete finishing systems were evaluated in an accelerated weathering test in QUV. The second part of the work is an exploratory study aiming to develop nanodisperse inorganic UV absorbers with optimized composition and morphology. Three compounds were thus tested namely CUB, HTB and RNE. Nevertheless their performances appeared quite insufficient during an accelerated weathering test simulating outside conditions.NANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Les finitions poudres appliquées sur le bois et matériaux dérivés (optimisation du procédé industriel, étude des relations finition/substrat et fonctionnalisation)

Les finitions poudres, utilisées avec succès dans l'industrie du métal, représentent aujourd'hui une alternative aux systèmes utilisés actuellement pour les substrats en bois. Cette technologie permet tout d'abord de répondre aux besoins des industriels de l'ameublement et de la menuiserie car elle est en parfait accord avec la Directive Européenne 1999/13/CEE sur la réduction des émissions des COV. De plus, l'arrivée sur le marché de formulations thermodurcissables à basse température et à polymérisation sous UV a permis d'appliquer cette technologie à des substrats thermosensibles tels que le bois et ses matériaux dérivés. Actuellement, la finition poudre donne de très bons résultats en termes de qualité sur le panneau de fibres (MDF). D'autres résultats prometteurs ont aussi été obtenus sur du contreplaqué ou du bois massif de hêtre. Etudier de près l'ensemble des facteurs influençant le procédé, en particulier la nature du support bois et sa préparation, les paramètres de poudrage et de cuisson sont les objectifs principaux l'optimisation de ce procédé à l'échelle industrielle. Par ailleurs, les interactions substrat-finition poudre, outre les caractéristiques chimiques des résines, semblent définir la qualité finale du système et sa durabilité vis-à-vis du vieillissement. Un axe supplémentaire de l'étude est de vérifier l'éventuelle fonctionnalisation des finitions poudres pour leur donner des rôles particuliers, comme par exemple l'apport d'une propriété antibactérienne ou l'adsorption de COV environnantsPowder coatings, successfully used in the metal industry, represent today an alternative to the systems currently used for wooden substrates. This technology allows first to respond to the needs of manufacturers of furniture and carpentry as it is in perfect agreement with the European Directive 1999/13/EEC on the reduction of VOC emissions. In addition, the arrival on the market of thermosetting formulations at low temperature or UV polymerization allows to apply this technology to heat-sensitive substrates such as wood and derivates. Currently, powder coating gives very good results in terms of quality on the fiberboard (MDF). Other promising results have also been obtained on plywood or solid beech. Study the factors influencing the process, in particular the nature of the substrate and its preparation, powdering and baking settings are the main objectives to optimize this process on an industrial scale. Furthermore, interactions substrate-powder coating, in addition to the chemical characteristics of resins, seem to define the final quality of the system and its durability against aging. An additional axis of the study is to verify the possible functionalization of powder coatings provide particular roles, such as for example the provision of an antibacterial property or the adsorption of surrounding VOCMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Biosorptive Removal of Zinc from Aqueous Solution by Algerian <i>Calotropis procera</i> Roots

International audiencePotentially toxic trace elements, such as zinc, with high levels in water are very serious problems in many places around the world, sometimes in relation to natural sources and in other cases to anthropogenic ones. Adsorption process is among the most effective techniques for removing of many heavy metal ions from different types of water. In this study, an attempt has been made to investigate the efficiency of Calotropis procera roots (CP) in removing of Zn(II) from aqueous solution by using batch mode technique. During the removal process, the effects of solution pH, Zn concentrations and contact time on adsorption efficiency by CP roots were studied. Experimental equilibrium data were analyzed by the Langmuir and Freundlich isotherm models. The results showed that the best fit was achieved with the Langmuir isotherm equation with maximum ad-sorption capacity of 9.69 mg/g. The biosorption of Zn(II) was a fast process and followed the pseudo-second-order kinetic

Changes in bioactive phytochemical content and in vitro antioxidant activity of carob (Ceratonia siliqua L.) as influenced by fruit ripening

International audienceIn the present study, three varieties (Wild, Fleshy and Sisam) of carob (Ceratonia siliqua L.) pods were analyzed for their bioactive phytochemical content and antioxidant activities (AA) at three ripening stages. The results showed that the samples have the highest total phenolic (TPC), total flavonoid (TFC) and ascorbic acid content (AAC) in the unripe stage. The antioxidant activity examined using free radical scavenging effect against 2-2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing power (FRP) and ferrous iron chelating (FIC) assays decreased significantly throughout the ripening. Extremely significant correlations (p < 0.001) were found between phytochemical compound contents (TPC,TFC and AAC) and assessed antioxidant activities, except between AAC and FIC where just a very significant correlation (p < 0.01) was recorded. Our data revealed that extracts of unripe C. siliqua L are an excellent source of natural antioxidants that might be more widely used in cosmetic, pharmaceutical and food industries

Adsorption of Congo Red from Aqueous Solution Using CTAB-Kaolin from Bechar Algeria

International audienceCetyltrimethylammonium bromide-modified kaolin (CTAB-kaolin or KC) was prepared and tested as an adsorbent for an anionic dye Congo red (CR) removal from aqueous solution in comparison with natural kaolin (K). The effect of various experimental parameters was investigated using a batch adsorption technique. In this manner, the adsorption isotherms and adsorption kinetics of CR on K and KC were examined. The isothermal data could be well described by the Langmuir equation and the dynamical data fit well with the pseudo-second-order kinetic model. The ad-sorption capacity of modified kaolin KC (24.46 mg/g) was found to be around 4 times higher than that of natural kaolin K (5.94 mg/g). The KC demonstrated the highest adsorption capacity by removing over 98% of CR after ten minutes of contact. These results indicate that CTAB-kaolin could be employed as low-cost alternative to activated carbon in wastewater treatment for the removal of colour which comes from industrial effluents of textile activities, tanning or printing

Enjeux relationnels et limites d’application des directives anticipées : étude qualitative exploratoire auprès de médecins

International audienceIn view of the development of advance directives (AD) in France since 2016, the aim of our study was to take a look at the knowledge of this measure, what it represents and how the doctors integrate it. We carried out a qualitative monocentric study by means of exploratory interviews with doctors (n = 12). An analysis of thematic content was made from these interviews. Analysis of the content of these conversations revealed limited knowledge of ADs, reservations regarding the role of doctors in this respect and a number of perceived limitations with regard to their implementation (complexity of end-of-life situations ; impact on care relationships ; psychological repercussions ; uncertainty ; “changing” nature of ADs ; the culture of care services). Psychosocial limits explain in part the reservation concerning this document and play a part in the hesitation about its “legitimacy” or “utility”. The challenge of developing the understanding of ADs must take into account the psychosocial conditions of its acceptability and its integration into care practices and relations.Dans le contexte du développement des directives anticipées (DA) en France depuis 2016, notre étude avait pour objectif d’étudier les connaissances, représentations et modalités d’intégration de ce dispositif auprès de médecins. Nous avons conduit une recherche qualitative monocentrique par entretiens de recherche auprès de médecins (n = 12). Une analyse de contenu thématique a été réalisée sur l’ensemble des entretiens. L’analyse de contenu des entretiens a mis en évidence une connaissance relative des DA, des réserves quant au rôle des médecins par rapport à ce dispositif et un ensemble de limites perçues concernant leur mise en œuvre (complexité des situations de fin de vie ; impact sur la relation de soin ; répercussion psychologique ; incertitude ; caractère « changeant » des DA ; culture des services de soins). Des limites d’ordre psychosocial expliquent en partie les réticences concernant ce dispositif et contribuent à une mise en question de sa « légitimité » ou « utilité ». L’enjeu du développement des connaissances sur les DA doit s’accompagner d’une réflexion sur les conditions psychosociales de son acceptabilité et de son intégration dans les pratiques et la relation soignantes