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Plywood made of poplar are limited to indoor usages since poplar exhibits a rather low natural durability. Recently, wood heat treatments have been applied to improve properties such as decay susceptibility and dimensional stability. This study examines the potential of exposing poplar plywood to heat treatment to extend the potential of applications of this engineered wood product to outdoor end uses, and new markets accordingly. Plywood panels were glued with two different adhesive formulations based on the same melamine-urea-formaldehyde (MUF) resin to compare their respective ability to resist to the heat treatment. These different plywoods were thermally modified in saturated steam conditions at 215 °C for 2 hours following the ThermoWood® process, up to reach 14% in mass loss. The durability improvement brought by the heat treatment was assessed in order to evaluate any possible outdoor uses for such plywood. After all the conducted analyses, the potential to use heat treated poplar plywoods in humid interior and protected exterior service conditions was confirmed. ANR-10-EQPX-16 XYLOFOREST laboratoire Mixte Public/privé qui associe les Arts et Métiers (campus de Cluny) et l’entreprise Brugère

Two assemblages compose the scuttled Roman vessels discovered in Caska inlet (Pag Island, Croatia): three sewn boats (Caska 1, 3 and 4) and one mortise-and-tenon constructed ship (Caska 2). While the wood species used for the construction of the sewn boats are quite similar (beech trunks split radially for planking), the construction of Caska 2 shows greater heterogeneity and more common use of conifer species for planking. The systematic identification of the wood species, the analysis of the morphological characteristics and the tree-ring dating of a large number of ship’s components provide new insight into ancient Adriatic shipbuilding traditions. Deux méthodes d’assemblages ont été observées sur les embarcations, coulées volontairement, découvertes à Caska (île de Pag, Croatie) : trois bateaux sont cousus (Caska 1, 3 et 4) et un quatrième est assemblé à tenons et mortaises (Caska 2). Si les essences de bois utilisées pour la construction des bateaux cousus sont assez similaires (troncs de hêtre fendus radialement pour le bordage), la construction de Caska 2 se révèle plus hétérogène et l’on observe une utilisation plus commune d’essences résineuses pour le bordé. L’identification systématique des essences de bois, l’analyse de leurs caractéristiques morphologiques et la datation des cernes d’un grand nombre des éléments des embarcations offrent un nouvel aperçu des traditions de la construction navale antique en Adriatique.

Vingt et un chênes pubescents, abattus dans l'Eure, ont été sciés en plots de 2 m et de 27 mm d'épaisseur. Une partie a été séchée à la scierie dans un séchoir industriel Cathild® de 30 m3 . Une autre partie a été séparée en 2 lots de 3 m 3 au Cirad ; le 1er lot séché selon la table définie par le Cirad, l'autre lot, selon la table Cathild®. L'analyse du Cirad montre que les déformations et défauts sont moins importants avec leur table, mais que la durée de séchage augmente en contrepartie (5 à 7 jours supplémentaires dans l'étude). Néanmoins, cette table spécifique reste compatible avec le séchage des autres chênes.

Transverse modal analysis of timber panels is a proven effective alternative method for approximating a material's elastic constants. Specific testing configurations, such as boundary conditions (BC) and location of sensor and impact, play a critical role in the accuracy of the results obtained from the experimental assessment. This article investigates signal-specific details, such as the signal quality factor, that directly relate to the damping properties and internal friction as well as frequency shifting obtained from six different BCs. A freely supported (FFFF), opposing minor sides (shorter length) simply supported, and major sides (longest length) free (SFSF), as well as the reverse of the SFSF configuration with minor sides free and major lengths simply supported (FSFS) and all sides simply supported (SSSS) setup, are investigated. Variations into the proposed methods used to achieve an FFFF supported system are also considered. A combination of experimental testing in parallel with finite element analysis was conducted to re-create the setup that would be used within a manufacturing facility for nondestructive assessment of full-size cross-laminated timber panels. The differences between all BC configurations for their resonance frequency quality and location indicate that a freely supported system provides higher-resolution results, good comparison of less than 10 percent error with the finite element analysis and experimental results, and advantages in a simple experimental setup for the intended application.

Au Bénin, les déchets issus de la transformation du bois sont très insuffisamment valorisés dans une perspective de réutilisation par l’industrie du bois. Les technologies de transformation de ces produits connexes, économiquement accessibles aux populations des pays en développement, constituent un domaine très peu abordé dans la littérature internationale. Dans le présent travail, un matériau constitué d’un mélange de sciure de bois de teck et de pâte de polystyrène recyclés, suivant une technologie simple à mettre en œuvre et de type low-tech, a été caractérisé. Les résultats obtenus ont montré que les propriétés du composite varient significativement avec la granulométrie de la sciure utilisée. La masse volumique apparente du matériau est comprise entre 686 à 826 kg/m3, son taux d’absorption d’eau est inférieur à 15 % et son taux de gonflement en épaisseur est inférieur à 5 % après 24 heures d’immersion. Une corrélation élevée a été observée entre ses propriétés physiques et sa porosité qui varie de 34 et 43 % suivant la granulométrie des sciures de bois utilisées. Le composite présente un module d’élasticité en traction compris entre 582 à 1 057 MPa, une résistance en traction comprise entre 2 et 3 MPa et un coefficient de Poisson variant de 0,14 à 0,24. En compression, son module d’élasticité varie entre 270 à 470 MPa et sa résistance entre 6 à 9 MPa. Une mise en œuvre du composite ainsi élaboré peut être envisagée en substitution du bois pour des éléments faiblement chargés comme des pièces de coffrage de construction légère.

Furfural (F) cannot be easily polymerized like furfuryl alcohol, but it is an aldehyde that can react with urea (U) to make a polymeric network. The possibility of preparing F/U polymer along with an acidic catalyzer (maleic anhydride; M) was evaluated as a means to improve some selected properties of birch (Betula pendula) wood. The F+U/M resin was introduced into the wood with a double treatment technology. The first step involved dilution of F in water and methanol, and the second step was immersion in a U/M aqueous solution. The color of treated wood was darkened after resin curing from brown to a spectrum of black depending on the amount of loaded resin. The 60 to 80% of materials were converted to a non-leachable polymer based on the different formulations. The water absorption and volumetric swelling of the treated samples decreased with an increase in weight percent gain (WPG). The analysis of mechanical strength showed that treatment with F + U/M reduced to some extent the hardness and the impact bending of wood, while modulus of rupture, modulus of elasticity, and compression parallel to the grain with WPG were increased. The exposure of the samples to the accelerated weathering showed noticeable changes in color and roughness.

This work concerns the field of recycling of waste intobuilding materials. It reports on the possibility ofrecovering plastic waste and related products fromthe wood industry, in construction. The objective ofthe study is to give added value to wood-plasticcomposites produced using the cold compressionmolding process, by improving their mechanicalproperties. Through the bending test, the influence oftwo manufacturing parameters - compactionpressure and drying temperature after molding - onthe mechanical properties, was evaluated for the caseof a composite based on tropical wood sawdustcoming from Benin and recycled polystyrene (CBPo).It appears that the compaction pressure and thedrying temperature are essential factors to considerwhen evaluating the mechanical performance of thecomposite. Increasing the compaction pressure to alimit value significantly improves the properties of thematerial. The optimal properties of CBPo wereobtained at a pressure of 7 MPa. Post-forming dryingat 100 ° C also significantly improved the performanceof the composite. In addition, thanks to its enhancednew mechanical properties, the CBPo is repositionedrelatively to other existing materials, thus making itpossible to think about new applications inconstruction., Ce travail concerne le domaine du recyclage dedéchets en matériaux. Il rend compte d’unepossibilité de valorisation de déchets plastiques et deproduits connexes de l’industrie du bois dans laconstruction. L’étude vise à donner une valeurajoutée à un composite bois-plastique élaborésuivant un procédé de moulage par compression àfroid, par l’amélioration de ses propriétésmécaniques. A travers un essai de flexion, l’influencede deux paramètres de fabrication - pression decompactage et température de séchage postmoulage- sur les propriétés mécaniques, a étéévaluée dans le cas d’un composite à base de sciuresde bois tropicaux venant du Bénin et de polystyrène(CBPo) recyclés. Il en ressort que la pression decompactage et la température de séchage, sont deuxfacteurs essentiels à considérer lors de l’évaluationdes performances mécaniques du composite.L’augmentation de la pression de compactage jusqu’àune valeur limite améliore significativement lespropriétés du matériau. Les propriétés optimales duCBPo ont été obtenues à la pression de 7 MPa. Leséchage post-moulage à 100°C, a également amélioréde façon significative les performances du composite.Aussi, par ses nouvelles performances mécaniques, leCBPo se repositionne par rapport à d’autresmatériaux existants permettant ainsi d’en envisagerde nouvelles applications dans la construction.

The torrefaction (mild pyrolysis) process modifies biomass chemical and physical properties and is applied as a thermochemical route to upgrade solid fuel. In this work, the catalytic effect of thermo-acoustic on oxidizing woody torrefaction is assessed. The combined effect of two acoustic frequencies (1411, 2696 Hz) and three temperatures (230, 250, and 290 &deg, C) was evaluated through weight loss and its deviation curves, calculated torrefaction severity index (TSI), as well as proximate, calorific, and compression strength analysis of Eucalyptus grandis. A new index to account for the catalytic effects on torrefaction (TCEI) was introduced, providing the quantitative analysis of acoustic frequencies influence. A two-step consecutive reaction numerical model allowed the thermo-acoustic experiment evaluation. For instance, the thermogravimetric profiles revealed that the acoustic field has a catalytic effect on wood torrefaction and enhances the biomass oxidation process for severe treatments. The kinetic simulation of the acoustic coupling resulted in faster conversion rates for the solid pseudo-components showing the boosting effect of acoustic frequencies in anticipating hemicellulose decomposition and enhancing second step oxidizing reaction.

International audience; The natural durability of wood is linked to its chemical composition and in particular the presence of metabolites called extractives that often possess chemical reactivity. For dealing with these compounds, wood degraders have developed detoxification systems usually involving enzyme families. Among these enzymes, glutathione transferases (GSTs) are involved in the decrease of the reactivity of toxic compounds. In this study, the hypothesis that the detoxification systems of wood decaying fungi could be indicators of the chemical reactivity of wood extracts has been tested. This approach has been evaluated using 32 wood extracts coming from French Guiana species, testing their antimicrobial ability, antioxidative properties, and reactivity against six GSTs from the white rot Trametes versicolor. From the obtained data, a significant correlation between the antimicrobial and antioxidative properties of the tested wood extracts and GST interactions was established. In addition, the chemical analysis performed on one of the most reactive extracts (an acetonic extract of Bagassa guianensis) has demonstrated oxyresveratrol as a major constituent. We were able to cocrystallize one GST with this commercially interesting compound. Taken together, the presented data support the hypothesis that detoxifying enzymes could be used to identify the presence of molecules of industrial interest in wood extracts.

To assess the potassium catalytic influence on the kinetic behavior of non-oxidative biomass torrefaction, two woody biomass samples (Amapai and Eucalyptus), as well as Miscanthus samples impregnated with three different K2CO3 concentrations (0.003 M, 0.006 M, and 0.009 M) were comprehensively studied. The solid thermal degradation kinetics were analyzed through thermogravimetric analysis in usual torrefaction conditions (275 °C during 68min and 10 °C.min−1 heating rate) and an original Potassium Responsive Numerical Path (PRNP). Therefore, a two-step reaction model with unified activation energies was integrated within a numerical method that considers the torrefaction severity influence for each potassium-loading content in all three biomasses. The proposed PRNP enables an accurate solid yield prediction (R2 > 0.9995). A strong (R2 between 0.91 and 0.99) and a significant ( p ≤ 0.0463) linear correlation was highlighted between the potassium content in biomass, the increasing reaction rates, and pre-exponential factors. The solid and volatile product distribution depicted faster and marked degradation for solid pseudo-components and anticipated a higher volatile release. The catalytic torrefaction severity factor determination enabled correlating treatment severity and kinetic rates showing better correlations than K% for wood biomass. The accurate results are conducive to developing numerical models that are essential for assessing solid fuel upgrading under catalytic effect in torrefaction plants.

Biomass potassium impregnation is used to increase thermal degradation by catalytically influencing the wood components’ conversion mechanisms during torrefaction. Chemical composition of the biomass, including potassium content and process temperature and time, appear as (catalytic or not) torrefaction parameters that impact weight loss, which can be considered performance indicators. The literature on torrefaction reports process performance evaluation by defining severity indexes. Evaluating the torrefaction performance by indexes provides valuable and dimensionless data as input in numerical modeling for up-scaling the analysis of production systems and assessing environmental products and processes. Nevertheless, no study presents an assessment of the torrefaction indexes correlating the potassium catalytic effects with the operating parameters (temperature and time) and the feedstock sensitivity, simultaneously. Therefore, this study examines the effect of biomass potassium impregnation on weight loss kinetics, employing different indexes such as the torrefaction severity index (TSI), the torrefaction catalytic effect index (TCEI), the catalytic index (CI) and modified torrefaction severity factor ( TSF mod ) to quantify the catalysis on torrefaction. Two hardwoods, Amapai (Brosimum potabile Ducke) and Eucalyptus (Eucalyptus urophylla × E. camaldulensis), were demineralized and impregnated with different K2CO3 concentrations and then torrefied at 275 °C for 80 min. The process results enabled the assessment of the accuracy of the correlation between the indexes and the non-condensable volatile release during catalytic torrefaction. The TCEI provided the identification of two catalytic enhancement regions marked by 15 and 17 min holding time for Amapai and Eucalyptus. The CI and TSF mod presented R2 ≥ 0.97 when validated against the TSI, supporting their accuracy as a performance indicator. The correlation between indexes and non-condensable gases presented significance for 88% of the evaluated cases. The results of the TSI, TCEI and CI indexes as performance indicators are conducive to quantifying the catalytic level for torrefaction operation, reactor design, and production of added-value biofuels.

Wood modification treatments based on lactic acid oligomers (OLA) and monomers (LA) enhance beech dimensional stability (up to 70%) and biological resistance (less than 3% weight loss according to EN113). Chestnut wood tannins natural biological activity might improve the modified wood durability with milder curing conditions. Treatment consisted of the impregnation of monomers or oligomers mixtures followed by curing (140 °C/160 °C for 48h). Tannins addition is almost inconsequential with oligomeric-based treatment but improved the monomeric-based treatment. In this case, modified wood biological resistance and product persistence were increased. OLA impregnated wood cured at 160 °C was always the best performing treatment regarding dimensional stability and durability, but the addition of tannins in LA systems conferred promising properties to wood allowing simplification of the modification process.

Premise of the Study : Basic wood density is an important ecological trait for woody plants. It is used to characterize species performance and fitness in community ecology and to compute tree and forest biomass in carbon cycle studies. While wood density has been historically measured at 12% moisture, it is convenient for ecological purposes to convert this measure to basic wood density, i.e., the ratio of dry mass over green volume. Basic wood density can then be used to compute tree dry biomass from living tree volume. Methods: Here, we derive a new exact formula to compute the basic wood density Db from the density at moisture content w denoted Dw, the fiber saturation point S, and the volumetric shrinkage coefficient R. We estimated a new conversion factor using a global wood technology database where values to use this formula are available for 4022 trees collected in 64 countries (mostly tropical) and representing 872 species. Key Results: We show that previous conversion factors used to convert densities at 12% moisture into basic wood densities are inconsistent. Based on theory and data, we found that basic wood density could be inferred from the density at 12% moisture using the following formula: Db = 0.828D12. This value of 0.828 provides basic wood density estimates 4–5% smaller than values inferred from previous conversion factors. Conclusions: This new conversion factor should be used to derive basic wood densities in global wood density databases. Its use would prevent overestimating global forest carbon stocks and allow predicting better tree species community dynamics from wood density.

Kysytty lehden OA politiikkaa 020419/MSö Impregnation of dry wood with pure lactic acid oligomers (OLAs) followed by heat treatment confers promising properties to wood because of OLA's good diffusion, in-situ polymerization and persistence in cell walls. Treatment provides drastic reduction of the equilibrium moisture content, high dimensional stability and good durability. The presence of water during treatment has been evaluated. Curing of OLA impregnated dry wood in humid atmosphere leads to a strong and global degradation of the material. OLA treatment of wet wood only impacts the water leaching rate negatively. Treatment of dry wood with OLA diluted in water additionally decreases the biological resistance and is not efficient for decreasing hygroscopicity. Treatment of dry wood with lactic acid solution leads to a lower polymerization level but confers good properties.

To perform a non-destructive evaluation of wood, the Christoffel equation is frequently used to describe the relationship between the ultrasonic wave velocity and the mechanical parameters. In the context of acoustical tomography imaging of standing trees, the key contribution of this numerical study is to determine the influence of mechanical parameters of the wood radial-tangential plane on the wave velocity computation using the Christoffel equation. Mechanical parameters from six species were selected. A sensitivity analysis was carried out by increasing and decreasing every parameter by a given percentage, and then by computing the variation of velocity for a set of wave direction of propagations. The evolution of the wave velocity, according to the direction of propagation, depended on the considered species; there was a difference between the softwoods and the hardwoods. The sensitivity analysis showed a bigger influence of the Young's moduli, followed by the Poisson's ratio, and finally by the shear modulus. However, these last two parameters cannot be neglected when using the Christoffel equation to solve the inverse problem of standing tree tomography. A proposed solution involves determining the propagation paths using the Young's moduli as variables and then inversing the set of equations in accordance with the overall parameters.

International audience; Instrument makers prefer wood species which not only have excellent acoustical properties, but also tend to keep their natural state when going through preparations and pretreatments. In this study long time water soaking, a common protocol among Iranian lute makers, was used to investigate the natural durability and dimensional stability of White mulberry (Morus alba L.). The wood of white mulberry, which is the only source for making Iranian lutes for more than a century, was examined for its natural resistance towards fungi and termites. Samples were also studied for their dimensional change during four months of water soaking. White mulberry, whether leached or unleached, showed to be a very resistant species towards both termites and fungi. Gradual removal of the extractives during water immersion resulted in an increase in partial shrinkage. It was concluded that water leaching, though not affecting the natural durability, tends to reduce the dimensional stability of white mulberry.; Los fabricantes de instrumentos musicales (lauderos) prefieren madera de especies que no solo tengan excelentes propiedades acústicas, sino que además tiendan a mantener su estado natural durante su fabricación y pretratamientos. En este estudio se hicieron pruebas de inmersión en agua, un protocolo común entre los lauderos iraníes, para determinar la durabilidad natural y estabilidad dimensional de la madera de mora blanca (Morus alba L.). La madera de esta especie, la cual es la única que ha utilizado para la fabricación de los laúdes iraníes por más de un siglo, fue probada para determinar su resistencia natural al ataque de hongos y termitas. Los especímenes fueron estudiados para detectar cambios en sus dimensiones durante cuatro meses de inmersión en agua. La madera en estudio, lixiviada o no, mostró muy alta resistencia tanto al ataque de hongos como al de termitas. La remoción gradual de extractivos durante la inmersión resultó en un incremento en la contracción parcial. Se concluyó que, aun cuando la lixiviación en agua no afecta la durabilidad natural, tiende a reducir la estabilidad dimensional de la madera de mora blanca. Palabras clave: estabilidad dimensional, instrumentos musicales, durabilidad natural, Reticulitermes flavipes (ex.santonensis), filtra-ción de agua, morera blanca (Morus alba L.).

This atlas presents technical information for professionals who process and use temperate or tropical timber. lt combines the main technical characteristics of 283 tropical species and 17 species from temperate regions most commonly used in Europe with their primary uses. Each data sheet is accompanied by two photos of sawn wood (flat sawn and quarter sawn, or flat sawn and half quarter sawn), two macro photographs, and for certain species, an illustration of how the wood can be used. This publication will be most useful to opera1tors in the wood industry, including producers (forest managers, operating companies, political decision-makers) and consumers (importers, traders, processors, purchasers, architects, main contractors and builders). The Atlas serves as a tool of reference for teaching and training in the forest and wood sectors in tropical regions. Its purpose is to promote the most appropriate uses for each species according to its characteristics and in line with the motto: "the right wood in the right place". This book was produced by the Wood team of CIRAD's BioWooEB Research Unit with financial support from the International Tropical Timber Organization (ITIO) and Agropolis Fondation. It is the product of thirty years of research in wood technology science, provided by numerous contributors. It was coordinated using version 7 of Tropix, released by CIRAD.

International audience; Forest plantation trials have been conducted in French Guiana since the early 1960s with over 138 tree species (70 native and 68 exotic). A recent study on their productivity in plantations (ForesTreeCulture project, 2013-2015) showed the high potential of three native species (Simarouba amara Aubl., Vochysia tomentosa (G. Mey.) DC., Bagassa guianensis (Aubl.)) and one West African species (Tarrietia utilis Sprague), all of which produced timber volumes in excess of 20 m3/ha/year. However, the properties of these as commercial species are known only from trees that have grown in their natural forest environment. This article describes the properties of their timber when produced in plantation conditions – density, shrinkage, elasticity, angle of the grain, durability – and discusses the future potential and uses of each. A fourth species, Cordia alliodora ((Ruiz & Pavon) Oken), was also selected for study although it has not yet been planted in French Guiana. This species is native to French Guiana and well known across Latin America for its timber and high potential for growth in managed environments.; Des essais de plantations forestières ont été menés en Guyane française depuis le début des années 1960 sur plus de 138 espèces (70 espèces natives et 68 espèces exotiques). Une étude récente sur la productivité de ces espèces en plantation (projet ForesTreeCulture, 2013-2015) a mis en avant le fort potentiel de production de trois espèces natives (Simarouba amara Aubl., Vochysia tomentosa (G. Mey.) DC., Bagassa guianensis (Aubl.)) et d'une espèce d'Afrique de l'Ouest (Tarrietia utilis Sprague) avec des volumes de bois produits supérieurs à 20 m3/ha/an. Cependant, les propriétés du bois de ces espèces commerciales ne sont connues qu'au travers d'arbres issus de forêt naturelle. Nous présentons les propriétés du bois de ces espèces en conditions de plantation – densité, retrait, élasticité, angle du fil, durabilité – et discutons de leurs potentiels et de leurs usages respectifs futurs. Une autre espèce, Cordia alliodora ((Ruiz et Pavon) Oken), a également été retenue bien qu'elle n'ait pas encore été plantée en Guyane française. Cette espèce, native de Guyane, est bien connue en Amérique latine pour son bois et son fort potentiel de croissance en milieu anthropisé.

Depuis 2006, le laboratoire de préservation des bois du Cirad est accrédité par le COFRAC (Comité français d'accréditation - accréditation n°1-1686) pour ses essais sur la durabilité des bois et produits dérivés du bois et sur l'efficacité protectrice des produits de préservation et des produits anti-termites. La mise en place de la fonction métrologie au laboratoire de préservation du bois est un facteur clé de l'amélioration continue des pratiques. De tous les essais de caractérisation des bois, les essais de résistance aux agents biologiques de détérioration sont les plus délicats. Ils visent en effet à évaluer et à quantifier l'impact d'organismes vivants, comme les champignons et les termites, sur une matière lignocellulosique. On apprécie facilement l'importance de la variabilité de cet impact lié lui-même à la diversité de ces organismes. La validité et la fiabilité des résultats dépendront ainsi directement de la qualité du processus métrologique mis en oeuvre, comprenant le choix des appareils de mesure, leur gestion et leur mise en conformité avec les normes internationales. Mots clés: Métrologie, accréditation, traçabilité, incertitude, essais biologiques.

Key message Wood machining is compulsory both for timber separation and the surfacing of wooden objects. The anisotropy, cellular nature and multi-scale level organisation of wood make its cutting complicated to study. During the last 50 years, most of the wood machining subjects were covered by French teams.[br/] Context: Woodcutting is a very old technology but scientific research is scarce on the subject. In the last 50 years much work on basic mechanisms as well as industrial processes has been done in France. [br/] Aims: The specific nature of wood introduces strong differences between wood and metal cutting processes. The paper focuses on French teams' contributions. [br/] Results: The basic aspects of the tool–material interaction for different basic modes in woodcutting are highlighted. In primary conversion such as sawing, veneer cutting or green wood chipping, huge progress comes from automation and the possibility of linking the process to log and product quality through new sensors. In secondary processing much has been done on the links between the cutting process, surface qualification and the properties of these surfaces for further processing, such as gluing or coating. Tool wear depends on the cutting process, timber quality, and species. Trade-offs are required in tool technology and coating technologies may improve tool life. [br/] Conclusion: A large amount of knowledge and innovation has come from 50 years of worldwide research effort, with France being particularly active in this period. The transfer of skills from metals cutting industry was often a key, but much is needed to move closer to both metal cutting sector and woodcutting skills among craftsmen.

Few studies have investigated the influence of environmental conditions on the within-tree variation in Eucalyptus wood traits. The genotype and environment effects and their interactions influence the wood properties. Their evaluations are crucial to estimate the genotype values and to select with efficiency. Thus, the aim of this study was to better understand the effect of ground slope and wind speed on the spatial variation of basic density (ρ), stiffness (MOE) and microfibril angle (MFA) of Eucalyptus wood. Wood discs cut along the trunk were sampled from one-hundred fifty 6-year-old Eucalyptus grandis × E. urophylla hybrids growing in three contrasting growing conditions influenced by ground slope and wind regime. Near infrared (NIR) calibrations previously developed for ρ, MOE and MFA were used to predict in our discs. 2-D plots presenting the spatial variation of predicted wood traits were compared. The higher the ground slope, the greater the magnitude of radial variation in ρ, principally in the medium zone of the trunk. The spatial variation of wood stiffness seems to be sensitive to two environmental conditions. The MFA radial decreases were more pronounced where the wind speed was higher. At the base and top of the trees, however, there was no significant effect of growing conditions on the radial variation of the wood properties considered here.

Wood is a multifunctional tissue involved in sap conduction, storage of water and reserves as well as mechanical support. Tree during its development experiments various constraints due to its environment and its growing size. In response to these constraints, wood functional performances are adjusted by variations of property values, which are dependent on the xylogenesis product. However, wood properties may be modified by the deposition of chemical extractives during heartwood formation. Thus heartwood properties are the result of xylogenesis, heartwood formation and their interactions. This work gave rise to the term 'wood profile', designating all variations of wood properties at different scales and in an ontogenetic dimension, resulting from both processes described above. The diversity of shade tolerance (heliophilic to sciaphilic) strategies species suggests a diversity of wood profile expressions. The description of these different expressions could be a way to better understand plant strategies. Understanding and characterizing wood profile and variations in heartwood quantity in tree, is an economical issue since the Guyanese timber industry has been identified as a promising sector. The analysis of the diversity of wood profile—using a bottom-up approach, from the individual level to the interspecific level—proves to discriminate shade tolerance strategies efficiently. Wood specific gravity variation is especially relevant. However, its relevance is based on (1) combinations of both radial and vertical variations and (2) integration of heartwood that may impact range and direction of the gradient and shape of the profile as well. Effect of heartwood formation on wood specific gravity variations is suggestive of shade tolerance strategy as well as quality and/or quantity of chemical extractives. Relevant characterization of shade tolerance strategies by wood profile is the result of the integration of diverse processes and properties. To the view of growth allocation shift (from trunk to crown) observed in Dicorynia guianensis and of previous studies on tree growth, a potential link between wood profile diversity and growth allocation strategies may exist.; Le bois est un tissu plurifonctionnel permettant la conduction de la sève brute, le stockage de l’eau et des sucres ainsi que le soutien mécanique de la plante. L’arbre au cours de son développement expérimente différentes contraintes liées à son environnement et à sa taille croissante. En réponse à ces contraintes, les performances fonctionnelles du bois sont ajustées par des variations de valeurs de propriétés, elles-mêmes dépendantes du produit de la xylogénèse. Cependant les extrais chimiques déposés lors du processus de duraminisation, entraine la modification des propriétés du bois. Les propriétés du duramen sont le fruit de la xylognénése et de la duraminisation ainsi que de leurs interactions. Ce travail de thèse a donné naissance au terme ‘profil ligneux’, désignant l’ensemble des variations des propriétés du bois à différentes échelles et dans une dimension ontogénique résultant des deux processus cités précédemment. La diversité de tempéraments vis-à-vis de la lumière (héliophilie à sciaphilie) des essences tropicales suggère une diversité d’expressions du profil ligneux.La description de ces différentes expressions serait gage d’une meilleure compréhension du tempérament.Comprendre et caractériser le profil ligneux et la variation de la quantité de bois de coeur dans l’arbre, représentent également un enjeu économique puisque l’industrie du bois Guyanaise a été identifiée comme une filière d’avenir. L’analyse de la diversité du profil ligneux—par une approche ascendante, de l’échelle individuelle à l’échelle interspécifique—a prouvé son efficacité dans la discrimination du degré d’affinité à la lumière. La variation de densité est particuliérment pertinente. Néanmoins, sa pertinence réside dans (1) la combinaison du gradient radial et vertical et (2) la prise en compte du duramen qui modifie parfois, l’amplitude et la direction du gradient ainsi que la forme du profil. L’effet de la duraminisation sur la variation de densité devient alors évocateur du tempérament de l’espèce au même titre que la qualité et/ou la quantité d’extraits chimiques mis en jeu. La pertinence du profil ligneux dans la caractérisation du tempérament écologique est due à son aspect intégrateur de divers processus et propriétés. En regard du changement de l’allocation de croissance (i.e. du tronc vers la couronne) observé chez Dicorynia guianensis et de travaux précédents sur la croissance des arbres, un lien potentiel entre la diversité du profil ligneux et la stratégie d’allocation de la croissance pourrait exister.

Perfil laminado de madera encolada para carpinterfa interior y exterior, que comprende una pluralidad de laminas (2) de pino negro, encoladas mediante adhesivo bicomponente (3) formado por una emulsion polimérica de isocianato y endurecedor libre de formaldehido. Procedimiento de fabricacion de un perfil laminado de madera encolada de pino negro.

2015 International Congress on Ultrasonics, Metz, FRA, 10-/05/2015 - 14/05/2015; International audience; The aim of this study was to find a relevant criterion to detect and map tree roots in the surrounding soil. In each experiment, we studied properties of propagation, especially velocity and attenuation of amplitude, as parameters to discriminate the roots from the soil. Our work was initiated by laboratory experiments with an ultrasonic transmission device to highlight relative differences between samples of soil and roots. Measurements were repeated on different root samples (species, dimension, decomposition time) to cover the diversity encountered on dikes. Then an intermediate state device reproducing in-situ conditions in laboratory was performed at the soil surface in two plastic containers: one control with only soil and another containing a buried root sample . We shown with laboratory experiments that information provided by the velocity term seems relevant to localize roots in the soil for healthy root samples. The study in containers gave similar results, significant variations of velocity being observed due to root presence.

Quebracho tannin wood adhesive in non formaldehyde approach has low autocondensation rate and needs more press time than formaldehyde-based wood adhesives to produce wood composites. In this study, boric acid was used to increase autocondensation rate of quebracho tannin adhesive to make poplar plywood. The main ingredients of the adhesives include quebracho tannin, NaOH, hexamine, boric acid and polymeric isocyanate (PMDI). Thermomechanical analysis of control adhesives (without boric acid) showed maximum Young's modulus values increased with increasing tannin initial concentration from 40% to 50% (m/m), while no significant effect has been found by adding 20% PMDI based on the tannin solid content. The addition of the boric acid not only (1) lowered time and temperature of hardening, (2) but also increased Young's modulus values of the adhesive by adding boric acid from 2% to 4% based on the solid content of the tannin.. Tensile shear strength of the plywoods confirmed thermomechanical previous results. Tensile shear values did not meet EN 314-2 requirements for interior plywood classification without boric acid systems. While boric acid significantly increased tensile shear values which had ascending trend with increasing boric acid and tannin concentration. The current study indicates that plywoods were made by 50% quebracho tannin and 2-4% boric acid meet the relevant performance requirements for interior applications.

International audience; Methods for measuring ultrasonic wave velocity in an elastic material require knowledge of the thickness of the sample. In general, the precision of this knowledge determines the accuracy of the experimental technique for measuring velocity. With the same restriction, measuring thickness of a material require a knowledge of the time-of-flight of the wave propagating. This problem is particularly acute in measuring parameters in wood specimen with an acoustical impedance contrast higher than the surrounding media. The aim of the present study was to compare chirp-coded excitation methods to determine time-of-flight, and to evaluate the precision of the measurement in function of several temporal durations. The apparent thicknesses and ultrasonic wave velocities in parallelepipedic plates of resin and wood material were measured using the method, and using, as reference, a pulse-mode approach. The relative errors of thickness measurement comparing to the results from caliper measurements are 0.1% to 6.81%. For velocity, the chirp-coded excitation method shows differences with reference method, from 0.78% to 3.64%.

Key message High-resolution imaging is possible if high-frequency sensors are used together with a signalprocessing and inversion algorithm that is well suited to a low signal-to-noise ratio and the effect of wood anisotropy. Wood is a biological growth medium, and given that standing trees adapt themselves in their growth to environmental conditions, their material properties vary with age. These changes result in variations that are far more complex than anisotropy. Wood quality and intraspecific variability can thus be studied to gain an understanding of the development mechanisms of trees, and this can be useful for clonal selection and the management of tree communities. A number of techniques are available to determine wood properties in standing trees, but the signal-processing approaches currently used are not always robust and do not always provide the image resolution needed in the particular cases of acoustic or ultrasonic tomography. This review paper thus aims to present important aspects that should be taken into account when using tomography techniques and addresses a number of open problems. A brief review of current non-destructive wood imaging techniques is initially presented followed by a comparison of the protocols, methods and models used in acoustic and ultrasonic tomography. The devices cited were studied in terms of measurement systems and signal processing. The analysis aimed to highlight and analyze the advantages and disadvantages of each device and describe challenges and trends. The effect of various parameters is discussed: frequency, signal-to-noise ratio, number of sensors and inversion algorithm. General conclusions are then drawn in relation to future signal-processing work in the acoustic and ultrasonic tomography of standing trees.

International audience; The current paper presents a study combining experimentation and modelling of char gasification in a continuous fixed bed reactor. The char bed gasification was experimentally characterized using the Continuous Fixed Bed reactor (CFiB) at CIRAD (Montpellier, France). This reactor replicates the gasification zone taking place in the co-current, multi-stage gasification technology. It is instrumented to specifically allow the measurement of thermal and chemical profiles: measurements of temperature, pressure, and gas composition are performed every 10 cm along the bed. We also investigate the char bed compaction during gasification. For this purpose, a char bed sampling was carried out to measure char bed density and particle velocities along the char bed. A model of wood char gasification in a continuous fixed bed reactor was thus developed using COMSOL software. It couples heat and mass transfer phenomena with heterogeneous and homogenous chemical reactions taking place inside the bed. In particular, this model considers char bed compaction to predict evolution of char bed density and velocity. As an innovative approach, three simple functions to calculate char particle conversion rate of the heterogeneous reactions were proposed.