Improvement of the durability of heat-treated wood against termites

Thermal modification is an attractive alternative to improve the decay durability and dimensional stability of wood. However, thermally modified wood is generally not resistant to termite attacks, limiting the field of application of such materials. One way to overcome this drawback is to combine thermal modification treatment with an additional treatment. One such treatment is the impregnation of a boron derivative associated with appropriate vinylic monomers, which takes advantage of the thermal treatment to polymerise these monomers for boron fixation. Using this strategy, we recently showed that an impregnation of borax (2 or 4% boric acid equivalent) dissolved in a 10% aqueous solution of polyglycerolmethacrylate followed by thermal treatment under nitrogen at 220°C protects wood from both termite and decay degradations, even after leaching. Additionally, wood samples treated with a 10% polyglycerolmethacrylate aqueous solution and subjected to thermal treatment at 220°C presented improved resistance to termites while avoiding boron utilization. Based on these results, we investigate the effect of impregnation with two types of vinylic monomers, which are already used in the presence of boron, followed by thermal treatments at different temperatures. We evaluate termite and decay durability of wood to evaluate if thermal modification associated with light chemical modification could be a solution for utilization of thermally modified materials in termite-infested areas

Heat treatment of poplar plywood: modifications in physical, mechanical and durability properties

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 Brugèr

Physical properties of four ring-porous hardwood species: influence of wood rays on tangential and radial wood shrinkage

Some relationships between ray proportions, strength and shrinkage properties and basic density in hardwood species were highlighted. A better understanding of their relationships caused by the variation in moisture content in the hygroscopic domain could be a key factor in determining of wood stability properties and to determine the choice of a specific wood species according to its service life condition. The objectives of this study were (i) to determine the physical properties of various ring porous wood species (ii) and to evaluate the influence of wood rays (according to their proportions and volume) on physical properties of wood and more particularly on the Transverse Anisotropy Ratio for Shrinkage (TARS). This study focused on four ring-porous hardwood species; Castanea sativa, Quercus canariensis, Quercus petraea and Quercus robur, differing by the presence and abundance of their multiseriate wood rays. Basic densities, tangential shrinkages, radial shrinkages and the TARS of heartwood and sapwood from each wood species were determined. Wood-rays’ proportions and volume were measured by the image analysis method, and their influence on the last three shrinkages was investigated. A significant correlation between wood ray proportions, wood shrinkage values and basic density was observed.Se destacaron algunas relaciones entre las proporciones de los radios, las propiedades de resistencia y contracción y la densidad básica en especies de madera de angiospermas. Una mejor comprensión de sus relaciones causadas por la variación en el contenido de humedad en el dominio higroscópico podría ser un factor clave para determinar las propiedades de estabilidad de la madera y para determinar la elección de una especie de madera específica de acuerdo con su condición de vida útil. Los objetivos de este estudio fueron (i) determinar las propiedades físicas de varias especies de madera porosa anular (ii) y evaluar la influencia de los radios de madera (de acuerdo con sus proporciones y volumen) en las propiedades físicas de la madera y más particularmente en la relación de anisotropía transversal por contracción (TARS, por sus siglas en inglés). Este estudio se centró en cuatro especies de angiospermas de porosidad anular: Castanea sativa, Quercus canariensis, Quercus petraea y Quercus robur, que se diferencian por la presencia y abundancia de radios multiseriados en su madera. Se determinaron las densidades básicas, las contracciones tangenciales, las contracciones radiales y la relación TARS de duramen y de albura de la madera de cada especie. Las proporciones y el volumen de los radios de madera se midieron con el método de análisis de imágenes, y se investigó su influencia en las últimas tres contracciones. Se observó una correlación significativa entre las proporciones de los radios, los valores de contracción y la densidad básica

Hybrid walnut wood quantity and quality: Agroforestry vs. Forestry systems.

International audienceOn an agroforestry plot, the services provided by agroforestry trees are numerous, especially on the economic front since they help improve the business model of the farm by diversifying activities and income for the farmer.However, agroforestry trees grow in very different conditions than forestry trees systems mainly because of their higher exposure to wind and light, specific competition for water availability, strong interactions with annual crops, numerous human operations on branches (pruning) and root systems. Production level and quality such as anatomical, chemical and technological properties of wood coming from agroforestry systems have not yet been studied. Such results could provide many interesting data to the farmers to promote access of agroforestry wood to conventional and/or niche markets...

Development of beech wood thermo-chemical modification treatments based on different vinylic derivatives of glycerol and polyglycerol

International audienc

Chemical composition, antitermite and antifungal activity of Dacryodes edulis oleoresin

International audienc

Caractérisations chimiques et activités antitermites des fractions volatiles et lourdes de Canarium schweinfurthii (Aiélé) du Gabon

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Efficacité de trois fractions de résine d'Aucoumea Klaineana Pierre du Gabon associées au Tébuconazole sur la préservation du bois

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Decay Resistance Variability of European Wood Species Thermally Modified by Industrial Process

Thermal modification is now considered as a new ecofriendly industrial wood modification process improving mainly the material decay resistance and its dimensional stability. Most industrial thermal treatment processes use convection heat transfer which induces sometimes heterogeneous treatment temperature propagation within the oven and lead to the heterogeneity in treatment efficiency. Thus, it is common that treatment is not completely effective on several stack boards, in a same batch. The aim of this paper was to study the decay resistance variability of various European wood species thermally modified. Thermal modifications were performed around 240°C during 4h, on about 10m3 of 27x152x2000mm3 wood planks placed in an industrial oven having a volume of 20m3 , on the following wood species: spruce, ash, beech and poplar. All of the tests concerning the decay resistance were carried out in the laboratory using untreated beech and pine woods as reference materials. An agar block test was used to determine the resistance of thermally modified woods, leached beforehand according to EN 84 standard or not, to brownrot and white-rot fungi, according to XP CEN/TS 15083-1. A large selection of treated wood samples was tested in order to estimate the variability of treatment efficiency. Thermal treatment increased the biological durability of all leached and un-leached modified wood samples, compared with native wood species. The treatment temperature of 240°C used in this study is sufficient to reach durability classes ‘‘durable’’ or ‘‘very durable’’ for the four wood species. However, the dispersion of weight loss values, due to the fungal attacks was very important and showed a large variability of the durability of wood which has been treated in a single batch. These results showed that there is a substantial need to develop process control and indicator in order to insure that the quality of treated timber is properly evaluated with a view to putting this modified timber on the market under a chain of custody