Étant donné son origine, le bois reste biodégradable et a besoin d'être protégé contre les agents abiotiques et biotiques afin d'avoir une longue durée de service. Les associations entre les tanins et l'acide borique peuvent être considérés comme un traitement innovant et respectueux de l'environnement. Ces formulations aqueuses de tannins et d'acide borique augmentent la rémanence du bore dans le bois traité. De plus, le bore est partiellement fixé au réseau polymère de tannins autocondensés dans le bois et garde suffisamment de mobilité pour garder son efficacité biologique. Ces associations ont été testées pour une application en extérieur, au-dessus et dans le sol, et pour leurs propriétés ignifugeantes. Une première formulation de tannin-hexamine et acide borique a montré une efficacité certaine face aux dégradations biologiques et au feu. Le comportement au vieillissement naturel et artificiel, au lessivage à l'échelle du laboratoire, ainsi que l'efficacité biologique résultante, de bois traité par ces associations a été étudié. Les résultats montent que ces trois vieillissements mènent à des performances biologiques différentes, toutes liées à la teneur en bore résiduelle. Une formulation tannin-bore dite améliorée, contenant du ɛ-caprolactame pour rendre le réseau polymère plus flexible (et éviter les craquelures comme dans la première formulation) a été étudiée pour les mécanismes chimiques mis en jeu, la résistance biologique au-dessus et dans le sol, et la résistance au feu. Le polymère à base de tannin acquiert une structure plus élastique après incorporation de ɛ-caprolactame, comme démontré par des analyses FT-IR. La résistance biologique du bois traité procure une résistance à long terme en extérieur, même dans le sol. L'effet de protection au feu est moins intéressant que pour la première formulation, mais reste toute de même plus important que pour le témoin. Afin d'améliorer l'efficacité des associations entre bore et tannins, l'élaboration de bois contenant un polymère nano-composite (Wood Tannin NanoComposite, WTNC) utilisant tannins, acide borique et montmorillonite a été étudiée. Des analyses FT-IR et XRD on permit d’identifier des nanoparticules d'argiles dans le WTNC. Par ailleurs, des traces de montmorillonite dans les parois du bois ont été observées en microscopie électronique à balayage. Par comparaison avec des témoins, la résistance à la compression du WTNC est plus importante, l'absorption d'eau et l'aptitude au collage du WTNC dépend de l'essence utilisée (pin sylvestre vs. Hêtre), la stabilité dimensionnelle du WTNC est légèrement abaissée et sa mouillabilité significativement réduite. La résistance à l'attaque de champignons et termites est améliorée dans des proportions variables selon que l'on utilise du pin sylvestre ou du hêtre. Les performances anti-feu des WTNC sont affectées différemment en fonction de l'essence de bois utilisée et des paramètres considérés. Cette étude analyse aussi les impacts environnementaux de la production de produit de préservation tannin-bore (pour la première formulation) et compare aussi les impacts du berceau à la tombe dans le cadre d'une analyse de cycle de vie de bois traité par cette formulation, en comparaison avec 2 formulations industrielles et du béton. Il apparaît que même si ces associations tannin-bore peuvent être encore étudiées plus avant et plus finement du point de vue chimique, pour leurs performances biologiques (vis-à-vis d'insectes coléoptères, essais de champ avec des termites, moisissures…), ainsi que pour leur profil éco-toxicologique, elles ont montré de réelles améliorations du bois dans les domaines de la résistance biologique et de la résistance au feu. / Due to its origins, wood remains biodegradable and needs to be protected against abiotic and biotic agents for a long service life. Tannin-boron associations can be considered as an innovative preservative formulation and environmentally-friendly treatment. These waterborne associations of tannins and boric acid increase the permanence of boron in the wood. Furthermore, boric acid is partly fixed to the network of autocondensed tannin in the wood and keeps sufficient mobility to maintain its biological action. These associations have been investigated for their outdoor applications, both above and in-ground, as well as for their ability for fire protection. An original formulation of tannin-hexamine and boric acid, has shown efficiency against biological attack and fire degradation. The natural and artificial weathering behaviour, and laboratory scale leaching, of such treated wood have been investigated, and followed by biological tests. The results showed that the weatherings led to different performances, always linked with the amount of remaining boron. An advanced tannin-boron formulation including ɛ-caprolactam to make the polymer network more flexible (and avoiding cracks as noticed for the original formulation) was studied for the chemical mechanisms, biological resistance above and in-ground, fire retardancy. The tannin polymer acquires a more elastic structure after adding ɛ-caprolactam, as seen with FT-IR analyses. The biological resistance of the treated wood provided a long lasting protection against degradation in outdoor exposures, and even in ground contact. However, fire retardant effect of this advanced tannin-boron preservative was negatively influenced with comparison to the original tannin-boron formulation, but still better than control. In order to improve the associations between boron and tannin for wood protection, the conception of wood polymer nanocomposite using tannin, boric acid and montmorillonite tentatively carried out. The analyses of FT-IR and XRD have investigated to identify nanoclay in Wood Tannin Nanocomposite (WTNC). Meanwhile, the trace of montmorillonite in wood cell is also captured by SEM. By comparison with control, compression strengths of WTNC samples increase; water absorption and gluing ability of WTNC depend on the wood species used (Scot Pine vs. Beech); dimensional stability of WTNC is slightly decreased, and wettability was significantly decreased. Fungal and termite resistance of WTNC are improved to different extends if Scots pine or beech samples are used. Fire performances of WTNC is affected differently depending on the wood species used and the parameters considered. This study also analyses the environmental impacts of producing tannin-boron (TB) preservative (the original formulation) and comparatively introduces the cradle-to-grave life cycle environmental impacts (LCA) of TB-treated timber as landscaping materials, compared with 2 industrial formulations and concrete.Even if all these tannin-boron association systems developed still need to be improved for some point of their chemistry, biological performances (coleoptera insects, field tests with termites, molds…), as well as for their eco-toxicological profile, they have shown to improve the biological and fire resistance of the wood.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2009. / Härtill 5 uppsatser.

Examination of the relationship between wood properties such as density, cell diameters and climate provides the opportunity to develop long-term climate and mass balance proxies, and is a key component to understanding when and how wood develops through time. This research sought to: create multi-proxy models to represent long-term changes in the climate-mass balance relationships at Place Glacier, and to describe glaciological changes in Mount Revelstoke and Glacier National Parks, British Columbia; use multiple wood properties to develop intra-annual climate records for tree-ring sites from the southern and northern interior regions of British Columbia; and, use climate as an indicator of wood quality by identifying historical climate impacts on wood development over time. Tree-ring samples from hybrid interior spruce (Picea glauca (Moench) Voss x engelmannii (Parry)) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were collected in north-central British Columbia; interior spruce, Douglas-fir, and subalpine fir (Abies lasiocarpa (Hooker) Nuttall) were collected from trees in the Pemberton area of British Columbia, and Engelmann spruce (Picea engelmannii Parry ex. Engelmann), subalpine fir, and mountain hemlock (Tsuga mertensiana Bongard Carrière) were collected from trees located within Glacier and Mt. Revelstoke National Parks. Tree-ring chronologies were constructed using standard ring width measurement techniques, densitometric methodologies, and using SilviScan technology. Relationships among the regional climate, snowpack, mass balance and various wood chronologies were identified and used as a basis for reconstructing proxy climate and mass balance data. A proxy snowpack record for Tatlayoko Lake was reconstructed using mean density and ring width chronologies. Maximum density and ring width chronologies were used to reconstruct winter and summer mass balance records for Place Glacier. Place Glacier was found to respond negatively to continental summer temperature regimes and positively to winter coastal precipitation events. A proxy record of maximum summer temperature was reconstructed for Revelstoke using maximum density and ring width chronologies; while maximum cell-wall thickness was used to reconstruct total August precipitation, and February snowpack from Golden was reconstructed from subalpine fir and mountain hemlock ring-width chronologies. Mass balance for glaciers in the Columbia Mountains was reconstructed using a combination of ring width, maximum density and maximum cell-wall thickness chronologies. The proxy mass balance reconstruction shows a general decline in ice mass over the time span of the net balance reconstruction. Two intra-annual proxy climate records were created for northern British Columbia. Mean June and mean July-August temperature chronologies were reconstructed for Smithers using ring width and maximum density, and for Fort St. James total May-June and July-August precipitation records were reconstructed using ring width, minimum density, and maximum cell-wall thickness. Wood parameters, including density, cell-wall thickness, microfibril angle, and cell diameter in Douglas-fir and interior spruce were reconstructed at five sites across British Columbia using temperature and precipitation data from local climate stations. Maximum cell-wall thickness was shown to be one of the most robust wood parameters to predict using temperature variables. Using a variety of tree-ring characteristics for time series reconstruction provides an opportunity to create multivariate models with greater predictive capabilities that correspond more closely to observed data sets, thereby allowing dendroclimatologists to predict climate data trends more robustly. Because individual wood parameters form at different times throughout the growing season in response to distinct seasonal climates, multiple proxy models allow for the development of intra-annual proxy climate and glaciological records. / Graduate

Sudan is endowed with a great diversity of tree species; nevertheless the utilization of wood resources has traditionally concentrated on a few species only. Despite of the richness of Sudan in most of basic factors required to establish forest based industries it still almost entirely dependent on imports to satisfy its needs of the products of such industries. There is an urgent need to assess the suitability of the local fibrous raw materials for industrial utilization, this would not only reduce imports, but they would also provide an economic incentive to the forestry and industrial sectors of Sudan. Sudan has a wide variation of climatic zones, thus; great variations are expected in the anatomical and physical properties between and within species grown in each zone. This variation needs to be fully explored in order to suggest best uses for the species. The present study was carried out to assess the suitability of Acacia seyal var. seyal Del and Balanites aegyptiaca (L.) Delile wood for pulp and paper making (PPM) and flooring industry, as well as to investigate the effect of rainfall zones on selected wood properties. For this purpose, a total of thirty trees per species were collected from four states in Sudan, namely: Blue Nile, North Kordofan, South Kordofan and White Nile. The study areas located in two precipitation zones. Zone one with 273 mm mean annual rainfall, and zone two with 701 mm mean annual rainfall. Wood samples in form of disc were obtained from two heights within each tree, which are 10 % and 90 % from the tree merchantable height. Anatomical, physical and mechanical investigations were conducted in order to test the wood properties of the study species. The studied anatomical properties were: fibre and vessel diameter, lumen diameter and wall thickness. In addition to fibre length and three fibre derived values, namely: flexibility coefficient, Runkel ratio and slenderness ratio. The trend of fiber length from pith to bark was determined. The anatomical composition was described. Wood density was investigated as a main physical property. Basic density as well as air dry density were measured in the current study. Additionally, the density was measured using X-ray densitometry method in order to assess its suitability as a valid tool for the study species density determination. The trend of wood basic density from pith to bark was also determined. Brinell hardness strength was measured in the transverse and radial sections. According to the study results, the fibre length of both species considered as medium (900 -1600 μm). However, Acacia seyal has longer fiber. Acacia seyal wood density considered heavy (≥ 720 kg/m³) while that of Balanites aegyptiaca is medium (500 - < 720 kg/m³). Depending upon the mean values of hardness strength in transverse as well as radial sections, the wood of both species can be classified as very hard (up to 146 N/mm2 hardness strength). Fibre length and wood density for both species followed the increase trend from the pith to the bark. The X-ray densitometry technique is considered as a valid tool for wood density determination for both species. For each species, some wood properties (in mature wood) were significantly affected by the water stress in the drier zone. For instance, Acacia seyal fibre length was negatively affected, while vessel wall thickness, basic density as well as hardness strength of the radial section were positively affected. In case of Balanites aegyptiaca the following properties were affected: vessel dimensions (negatively) and basic density (positively). However, the water stress did not affect Acacia seyal fibre and vessel diameter and lumen diameter, fiber wall thickness, flexibility coefficient, Runkel ratio and hardness strength in transverse section. Balanites aegyptiaca fibre characteristics and hardness strength did not show any response to water stress as well. In general, the overall wood properties of the study species considered compatible for PPM and flooring industry. However, trees growing in the more humid zone are preferable for both industries, due to their lower wood density and longer fibres in case of Acacia seyal and lower density in case of Balanites aegyptiaca.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 6 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 3 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.