Literatura académica sobre el tema "Wood densification"

For optimum utilization of coconut wood, there are necessity to improve the quality of the wood caused by higroscopicity, low dimensional stability, and extreme variability of dimension in lateral direction. The purpose of the research were to analyze the characteristics of coconut wood that had been treated by heating and densification. The treatment consist of one or two hours heating, one hour heating combined to 10 or 20% densification, two hours heating combined to 10 or 20% densification. Temperature that applied for all specimen were 180 oC. The research results are as follows: (1) Heating treatment combined to densification effective to reduce higroscopicity of coconut wood, (2) Heating treatment for two hours are suffice as pretreatment to densify the soft part of coconut wood for 20%, (3) Dimensional stability of coconut wood may improve using heating combined to densification treatments that indicated by decreasing rate of dimensional change, (4) Heating and densification treatment effective to improve the hardness of soft part coconut wood. Keywords : coconut wood, heating treatment, densification References

Alnus acuminata, Vochysia ferruginea, and Vochysia guatemalensis are three low-density wood species used for reforestation in Costa Rica. The goal of this work was to study a thermo-hydro-mechanical densification process and test the characteristics of densified wood of these species. Twelve densifying treatments based on temperature, compression time, and use/no use of steam were tested. The variables of the densification process and the properties of the densified wood were determined. The results showed that the densification percentage was over 80% for wood of A. acuminata and over 70% for wood of V. ferruginea and V. guatemalensis. In the three species, the densification process was influenced by initial density. The influence of temperature during the densification process affected the heating rate and color change. An increase in the modulus of elasticity and modulus of rupture in static bending and in the hardness of the densified wood relative to the normal wood was observed, as well as a clear positive correlation of the properties with final density and maximum load, the latter being highly correlated with initial density. This showed that initial density was significant in the densification process and affects wood properties.

Densification process of biomass to the form of high-grade solid biofuel (briquette or pellet) is influenced by amount of technological factors. Size fraction and moisture content of raw material have the most importance. The densification process may be describing by complicated mathematical models based on behaviour of pressed particular matter. Therefore it is complicated to energy optimize the process. This paper deals with a methodology for determining the compressibility for pine sawdust on the basis of experiments. It also specifies the effectiveness criterion for biomass densification in order to optimize the densification process in terms of energy input. The experiments were performed in two stages. The first stage was an experimental investigation of the influence of size fraction and moisture content on the final compressibility of pine sawdust. High-pressure binderless densification of pine processing residues in the form of sawdust was studied. A piston-and-die process was used to produce densified briquettes under 20 °C temperature and at pressure up to 159 MPa. The results show the behaviour of the pressure load when the parameters of the particulate matter are changed. In the second stage, the experiments were evaluated and optimized to achieve minimum energy input of the process and a maximum degree of densification. For this purpose the Effectiveness Criterion for Densification was designed

This study investigated the evolution of the density, gas permeability, and thermal conductivity of sugar maple wood during the thermo-hygro-mechanical densification process. The results suggested that the oven-dry average density of densified samples was significantly higher than that of the control samples. However, the oven-dry density did not show a linear increase with the decrease of wood samples thickness. The radial intrinsic gas permeability of the control samples was 5 to 40 times higher than that of densified samples, which indicated that the void volume of wood was reduced notably after the densification process. The thermal conductivity increased by 0.5–1.5 percent for an increase of one percent moisture content for densified samples. The thermal conductivity of densified wood was lower than that of the control samples. The densification time had significant effects on the oven-dry density and gas permeability. Both densification time and moisture content had significant effects on thermal conductivity but their interaction effect was not significant.

In traditional timber structures, hardwood connectors such as a nails, wedges, dowels and pegs have been used as reinforcement of carpentry joints or to fix wooden ceiling matts or floor boards. In the study reported, the possibility to rely on enhanced mechanical and technological properties of densified wood, for the production of wooden nails to be used in the repair of traditional timber structures is discussed. The wood used for connectors were domestic wood species; ash, beech, black locust and poplar. Wooden blocks were exposed to densification procedure with the purpose of increasing the materials density, dimensional stability and possibly, improve durability and selected mechanical properties. The densification ratio varied between 50 and 67%. A dedicated research has been performed in order to determine the effect of densification on the compression behavior of wood in the form of nails. The progress of pushing force during insertion of the wooden nails into wood samples was also monitored and served for insertion process control. A preliminary series of push-out tests have been carried out on timber-to-timber joints assembled with the densified nails.The results obtained show potential for using the novel wooden nail connectors for substitution or integration repair works in traditional timber systems.

Purpose – This paper developed a new method of making floor from poplar using glued technology and densification technology. This paper aimed to use fast-grown poplar wood to produce floor to expand material supply range of floor in order to solve problem of material supply shortage for floor industry. Design/methodology/approach – Densification technology and gluing technology were used to obtain high-density surface materials of floor under high pressure, meanwhile in order to reduce loss of poplar wood caused by compressing, high-density surface materials floor and substrate are glued and pressed under low pressure. Findings – The method of compressing poplar wood under high pressure can improve poplar's physical and mechanical properties. Adopting densification technology and gluing technology can produce the poplar laminated composite floor which meets the requirements of Chinese standard GB/T 18103. Research limitations/implications – This method of producing floor by compression densification technology would cause wood loss from reduction in thickness because poplar was pressed under high pressure. Practical implications – This method of making floor from poplar wood concerned in this study allows the floor making industry to eliminate its dependence on precious wood resource, expand supply range of floor material, and then solve problem of wood supply shortage of floor industry. Originality/value – This study may help solve the difficult problem that poplar cannot directly be used to produce floor because of its softness, low density and low strength. Through densification technology, great improvement in strength and hardness of poplar had been made.

PurposeThe purpose of this study is the numerical investigation of densification and molding processes of wood. Providing theoretical and numerical approaches with respect to a consistent multi-physical finite element method framework are further goals of this research.Design/methodology/approachConstitutive phenomenological descriptions of the thermo-mechanical and moisture-dependent material characteristics of wood are introduced. Special focus is given to a consistent hygro-thermo-mechanical modeling at finite deformations to capture the realistic material behavior of wood, especially when it is subjected to densification and molding processes.FindingsRealistic theoretical formulations of different hygro-thermo-mechanical processes are provided. A successful numerical modeling is demonstrated for beech wood by validation at experimental findings.Originality/valueThe constitutive laws and numerical findings are new, as they govern a multi-physical large deformation framework and are applied to the advanced technology of densification and molding of wood.

The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. The THM densification process was performed at two different temperatures (180 °C and 200 °C) with and without steam. The functional groups, surface chemical composition and internal structure and components of the control and densified samples were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray photoelectron (XPS) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The obtained results suggest that the THM densification treatment resulted in significant chemical changes on the wood surface. The results of the ATR-FTIR spectra confirmed the decomposition of hemicelluloses and the relative increase of cellulose and lignin contents on the wood surface. The Py-GC/MS and XPS results show an increase of the oxygen/carbon atomic (O/C) ratio, which indicated that chemical substances containing oxygenated functionality were formed through the densification process. The densification treatment favored the depolymerization of hemicelluloses and cellulose as indicated by an increased anhydrous sugar (levoglucosan) release during the pyrolysis process. Densification also facilitated the cleavage of the lignin side chains, resulting in increased phenyl units with short chains released during the pyrolysis process.

British Columbia (BC) has become a major producer and exporter of wood pellets in the world. But the low energy density, the low water resistivity, the short shelf life, and the transportation cost impede the market development. Torrefaction, a thermal treatment without air or oxygen at 200-300°C, may provide a solution. The present study developed the torrefaction kinetics of BC softwood residues in a thermogravimetric analyzer (TGA), studied the effect of the torrefaction reaction conditions on the properties of torrefied sawdust in a bench-scale fixed bed reactor and a bench-scale fluidized bed reactor, and identified the suitable conditions for making durable torrefied pellets in a press machine using torrefied samples. The weight loss of BC softwood residues significantly depended on the torrefaction temperature, the residence time, the particle size, and the oxygen concentration in the carrier gas. The weight loss could be approximately estimated from the weight loss of the chemical compositions. A two-component and one-step first order reaction kinetic model gave a good agreement with data over short residence time on the weight loss range of 0 to 40% at the temperature of 260-300°C. The heating value of torrefied pellets had a close relationship with the weight loss, increasing with increasing the severity of torrefaction. The torrefied samples were more difficult to be compressed into strong pellets under the same conditions as used for making the control (regular, untreated, conventional) pellets. More energy was needed for compacting torrefied samples into torrefied pellets. Increasing the die temperature and adding moisture into torrefied samples could improve the quality of torrefied pellets. The moisture content and density of torrefied pellets were lower than control pellets. Considering the quality of torrefied pellets, the optimal torrefaction conditions appeared to correspond to a weight loss of about 30%, which gave a 20% increase in pellet heating value and good hydrophobicity. The suitable densification conditions corresponded to a die temperature of 230°C, or over 110°C for torrefied samples conditioned to 10% moisture content.

For wood products such as flooring and worktop, only one surface is normally exposed in their use, and the mechanical properties like hardness and wearing resistance of that surface is then important. Since mechanical properties are strongly related to the density, surface densification, i.e. transverse compression of the wood cells beneath the surface of a piece of wood with the aim to increase the density of that region, may be a method for improving hardness and wearing resistance when low-density species are used for such products. The set-recovery, i.e. the moisture-induced swelling of the densified wood cells back to their original shape, is the main obstacle in the use of densified wood products. Although there are several methods reported in literature, such as post heat-treatment, that can almost eliminate the set-recovery, but such methods are either time consuming or difficult to implement into an industrial continuous process which may do densification competitive to techniques or materials that can achieve at least the same hardness.     In the present study, furfuryl alcohol was used as pre-treatment to fix the set-recovery of surface-densified Scots pine sapwood. The main effect and interactive influence of four process parameter (impregnation time, press temperature, press time and compression ratio) on set-recovery and Brinell hardness after two wet-dry cycles were studied by a two-level full factorial design of experiments. The characterizing variables of the density profile after the surface densification and set-recovery test were carried out as a supplementary tool to learn the mechanism of this two-step modification process. According to the result, the surface densified wood with furfuryl alcohol pre-treatment can retain their dimension and keep hardness at a very high level after two wet-dry cycles. The set-recovery and hardens after two wet-dry cycles were about 20 % and 30 N/mm2, respectively. The Pearson correlation analysis shows that the correlation coefficients between set-recovery with impregnation time, press temperature, press temperature, compression ratio were -0.35, -0.52, -0.37, and 0.16, respectively. That means that for the specimens with furfuryl alcohol pre-treatment, the higher press temperature can reduce the set-recovery significantly. The longer press time and impregnation time can also reduce the set-recovery in some extent, but the influence was  low. As expected, the hardness improvement was retained with low set-recovery. The lowest set-recovery value was 14% with the corresponding hardness of 41 N/mm2 was achieved by specimens processed with 120 minutes of impregnation, 10% compression ratio, 210℃ pressing temperature, and 15 minutes of pressing time. With 20 minutes of impregnation time, 10% compression ratio, 210℃ pressing temperature, and 5 minutes of pressing time, the sample still owns twofold hardness after the set-recovery test.

Cette thèse présente une étude expérimentale et numérique sur les aptitudes en service en ce qui concerne le comportement vibratoire de planchers réalisés en bois d’ingénierie sans colle (AFEWP), à savoir les poutres en bois lamellé sans adhésif (AFLB) et les panneaux en bois lamellé-croisé sans adhésif (AFCLT), assemblés par des tourillons en bois densifié (CWD). Les analyses modales expérimentales ont été réalisées en conditions libres-libre à l'aide d'un marteau instrumenté. Les fréquences naturelles, les modes propres et les coefficients d'amortissement ont été évalués expérimentalement. De plus, des poutres en bois lamellé-collé similaires ont été fabriquées et testées à des fins de comparaison. Un modèle EF 3D a été développé et validé par comparaison avec des données expérimentales, puis utilisé pour prédire le comportement vibratoire d'un système de plancher à grande échelle réalisé avec un panneau AFCLT mesurant 4,5 m x 5,5 m. Une étude paramétrique a été réalisée en utilisant le modèle EF pour identifier les paramètres qui influent sur la rigidité et les fréquences propres du plancher. Les résultats obtenus ont été analysés au regard des critères de conception exigés par Eurocode 5 en ce qui concerne le confort vibratoire des planchers bois. Un modèle EF simplifié a ensuite été développé pour réduire les coûts de calcul. Le niveau de variabilité des résultats des AFEWP a été également étudié et discuté. La variabilité numérique des fréquences des AFEWP a été étudiée en utilisant la méthode MSP (Modal Stability Procedure). Les résultats de la méthode MSP ont d'abord été comparés aux résultats EF dans le cas nominal. Les résultats statistiques (valeur moyenne, écart type, coefficient de variation et distribution) obtenus par la méthode MSP ont été confrontés aux résultats de simulation directe de Monte Carlo ainsi qu’aux données expérimentales. Une estimation rapide des erreurs entre la méthode MSP et la simulation directe de Monte Carlo a été développée. Enfin, la variabilité (moyenne et écart-type des fréquences) du comportement vibratoire du système de plancher à grande échelle a été étudiée en utilisant la méthode MSP<br>This study presents an experimental and numerical investigation on the vibrational serviceability performance of novel adhesive free engineered wood products (AFEWPs), namely adhesive free laminated timber beams (AFLB) and adhesive free cross-laminated timber panels (AFCLT), assembled through thermo-mechanically compressed wood dowels (CWD). The experimental modal analyses were carried out under free-free conditions using a hammer impact. Natural frequencies, mode shapes, and damping ratio were assessed experimentally. In addition, similar glued timber beams (conventional glulam) were manufactured and tested for comparison purpose. A 3D FE model was developed and validated by comparison against experimental data and then used to predict the vibrational behavior of a realistic flooring system made with AFCLT panel measuring 4.5 m x 5.5 m. A parametric study was performed on the FE model to maximize the floor stiffness. The predicted FE results were discussed with regard to the Eurocode 5 vibrational serviceability design requirements showing acceptable vibrational performance. A simplified FE model was then developed to reduce computational cost. The variability level of the results for the AFEWPs was also studied and discussed. The numerical variability of frequencies of the AFEWPs was investigated based on the development of the Modal Stability Procedure (MSP). The MSP result was first compared with the FE result in the nominal case. Then, the statistic results (mean value, standard deviation, coefficient of variation and distribution) obtained from the MSP were compared with the results from the classical method (direct Monte Carlo simulation) and experimental results. A quick error estimation between the MSP and the direct Monte Carlo simulation was developed. Finally, the mean and standard deviation of the frequencies of the realistic AFCLT flooring system were predicted by the MSP

L’évolution des lois relatives à l’utilisation de produits biocides impose d’étudier des méthodes innovantes de traitement du bois. Dans ce contexte, les travaux de recherche présentés s’intéressent à une nouvelle alternative dite « non-biocide » impliquant la fabrication de composites bois massif / polymères obtenus par imprégnation de monomères et polymérisation in situ provoquée par chauffage. Le méthacrylate de méthyle, quatre acrylates organiques et trois acrylates hydrosolubles, ainsi que l’alcool furfurylique ont été testés. Les composites fabriqués ont été caractérisés : le polymère est bien présent dans le bois et il peut être résistant au lessivage à l’eau. Le bois a été densifié, les composites sont alors moins hydrophiles et plus stables dimensionnellement ; les propriétés mécaniques sont améliorées. Le traitement peut induire une durabilité conférée élevée. Parallèlement, une méthode d’imprégnation innovante a été testée : l’imprégnation axiale. Ce procédé consiste en l’imprégnation basse pression de billons de bois vert par une solution de traitement transitant via les voies naturelles de circulation de la sève. Des billons ont été imprégnés avec une solution de cuivre, dosé ultérieurement afin de s’assurer de la bonne répartition du produit dans le bois ; cela a permis la validation du procédé d’imprégnation axiale pour le hêtre, le charme et le bouleau. Enfin, des composites ont été fabriqués par imprégnation axiale de solutions aqueuses polymérisables à base d’alcool furfurylique ; ils sont résistants à la lixiviation à l’eau et moins hydrophiles que le bois naturel. Leur durabilité face aux champignons lignivores est améliorée, particulièrement dans le cas du traitement le plus concentré<br>The evolution of laws on the use of biocide products makes it necessary to explore innovative methods of treating wood. In this context, the presented research focuses on a new alternative called a "non-biocide" treatment method involving the manufacture of solid wood-polymer composites obtained by impregnation of monomers and in situ polymerization caused by heating. Methyl methacrylate, four organic acrylates and three water-soluble acrylates, and furfuryl alcohol were tested. Composites manufactured were characterized: the polymer is present in the timber and may be resistant to leaching in water. Wood has been densified, while the composites are less hydrophilic and more dimensionally stable; the mechanical properties are improved. Treatment can induce high durability. Otherwise, an innovative method of impregnation was tested: axial impregnation. This process consists in the low-pressure impregnation of green wood ridges by treatment solution transiting via natural pathways of sap circulation. Ridges were impregnated with a copper solution, later determined to ensure good distribution of the product in the timber; this allowed the validation of the axial impregnation method for beech, hornbeam and birch. Finally, the composites were produced by axial impregnation of polymerizable aqueous solutions based on furfuryl alcohol; they are resistant to water leaching and less hydrophilic than the original wood. Their durability in the presence of wood-destroying fungi is improved, particularly in the case of the more concentrated treatment

Densification is a well-known method for improving the mechanical properties of wood. In the present study, unmodified and furfurylated wood samples were densified and submitted to cyclic water storage tests and cyclic alternating climate tests. Swelling coefficients and spring-back data were determined for the evaluation of the quality of densification. The study shows that results depend on the test method applied. Simple water storage tests do not reflect the behavior of densified wood in the high humidity range. The spring-back data of unmodified samples are more influenced by the testing method than those of the furfurylated ones.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Thermomechanical treatments seek to increase the wood density, throught of the temperature and pressure combination, which results in a material with improved physical and mechanical properties. Thus, the study aimed to evaluate the influence of thermomechanical treatments in Pinus elliottii Engelm and Eucalyptus grandis W. Hill ex Maiden wood. So, were prepared from five trees of each species, wood pieces that have been submitted to six different thermomechanical treatments. For this purpose, we used a laboratory oil bath to perform preheating of wood and a hydraulic press with the temperatures of the dishes ranging from 150 to 190°C. Compression time used was between 30 and 60 min. After, physical (compression rate, weight loss, equilibrium moisture content, density, dimensional stability and hygroscopicity), mechanical (static bending, dynamic bending and Janka hardness), surface (colorimetry and roughness) and infrared spectroscopy (ATR-IR) tests were performed. For statistical analysis, we used qualitative factorial 3 x 2, with three temperature levels and two compression time and Tukey test. Furthermore, it was performed to compare the treatments with the control. The main results for the technological properties showed that the degree of compression and mass loss increased with the temperature increase. The equilibrium moisture content decreased and the density obtained increases. For the dimensional stability was observed that there was a reduction of the effect of the return densified wood, and hygroscopicity was increased in both wood species. The mechanical properties showed increases with the densification, except for the Janka hardness and dynamic flexion in E. grandis wood treated with high temperatures. Infrared spectroscopy showed degradation of the amorphous cellulose and hemicellulose, providing a proportional increase of crystalline cellulose and lignin. The color of the densified wood was changed presenting surface browning, measured by decrease in brightness L* parameter. Roughness was reduced, making the surface softer wood. Before the alterations, it is indicated using thermomechanical treatment with temperature of 150°C and the compression time of 60 min. In this respect, it is recommended the use of densified wood floors and coatings, even for softwoods (conifers).<br>Os tratamentos termomecânicos visam aumentar a densidade da madeira, por meio da combinação entre temperatura e pressão, o que resulta em um material com as propriedades físico-mecânicas melhoradas. Nesse sentido, o presente estudo teve como objetivo avaliar a influência dos tratamentos termomecânicos na madeira. Para tanto, foram confeccionadas peças de madeira, a partir de cinco árvores de Pinus elliottii Engelm e Eucalyptus grandis W. Hill ex Maiden que foram submetidas a seis tratamentos termomecânicos. Para tal, foi utilizado um banho de óleo laboratorial para realizar o pré-aquecimento da madeira e uma prensa hidráulica com a temperatura dos pratos variando de 150 a 190°C e o tempo de compressão entre 30 e 60 min. Na sequência, foram realizados os ensaios físicos (grau de compressão, perda de massa, teor de umidade de equilíbrio, densidade, estabilidade dimensional e higroscopicidade), mecânicos (flexão estática, flexão dinâmica e dureza Janka), de superfície (colorimetria e rugosidade) e espectroscopia no infravermelho (ATR-IR). Para a análise estatística foi utilizado o arranjo fatorial qualitativo 3 x 2, com três níveis de temperatura (150, 170 e 190°C) e dois de tempo de compressão (30 e 60 min) e comparados pelo teste de Tukey. Além disso, foi realizado a comparação dos tratamentos com o controle pelo teste de Dunnett. Os principais resultados encontrados para as propriedades tecnológicas mostraram que o grau de compressão, a perda de massa e a densidade aumentaram com o acréscimo da temperatura, já o teor de umidade de equilíbrio apresentou decréscimo com a elevação da temperatura. Para a estabilidade dimensional foi observado que houve redução pelo efeito do retorno da madeira densificada e a higroscopicidade foi aumentada na madeira de ambas as espécies. As propriedades mecânicas apresentaram acréscimo com a densificação, com exceção para a dureza Janka e flexão dinâmica da madeira de E. grandis tratada com altas temperaturas. Por meio da espectrometria no infravermelho foi verificado a partir da razão de pico que houve degradação de hemiceluloses e celulose amorfa, proporcionando aumento proporcional de celulose cristalina e lignina. A coloração da madeira densificada foi alterada apresentando escurecimento superficial, quantificado pelo decréscimo do parâmetro de claridade L*. Já a rugosidade foi reduzida, tornando a superfície da madeira mais suave. Diante das alterações ocorridas é indicado utilizar tratamento termomecânico com a temperatura de 150°C e o tempo de compressão de 60 min. Nesse aspecto, é recomendado a utilização da madeira densificada como assoalhos e revestimentos, mesmo para as madeiras macias (coníferas).

Para tornar a biomassa disponível para aplicações em biocombustíveis, produtos químicos e materiais, algumas propriedades indesejáveis, como alto teor de umidade e baixa densidade, devem ser corrigidos. Uma solução para estes problemas seria a densificação da biomassa. O processo de densificação da biomassa e seus resíduos, como a briquetagem e a peletização, são muito conhecidos e utilizados, entretanto, não existe um consenso sobre os mecanismos de ligação que ocorre entre as partículas da biomassa densificada e a influência que as variáveis da matéria-prima e do processo de densificação exerce sobre eles. Compreender os mecanismos de ligação entre as partículas da biomassa densificada é fundamental para determinar os parâmetros da matéria-prima e do processo de densificação, assim como os ensaios que devem ser realizados para medir a qualidade do produto densificado. Este trabalho teve como objetivo principal analisar o efeito das variáveis do material e do processo de densificação da serragem de madeira nas propriedades do produto densificado e a sua influência sobre os mecanismos de ligação entre as partículas do material. O material utilizado neste trabalho foi a serragem de Eucalyptus sp. Foram analisados o efeito do teor de umidade do material e a temperatura do processo de densificação na densidade e resistência mecânica do produto densificado, como também a influência da composição química da serragem na transição vítrea do material. A serragem de eucalipto foi caracterizada por análise termogravimétrica (TGA), caracterização química e espectroscopia de infravermelho por transformada de Fourier (FTIR). A caracterização de serragem densificada foi realizada por densidade aparente, expansão volumétrica, ensaio mecânico de compressão, microscopia eletrônica de varredura (MEV), microscopia ótica (MO), espectrometria de massa de íons secundários por tempo de voo (ToF-SIMS) e análise dinâmico-mecânica (DMA). Os resultados mostraram que no processo de densificação sem aquecimento, o teor de umidade ideal da serragem de eucalipto foi o de aproximadamente 10%, favorecendo as forças intermoleculares entre as partículas do material. Na densificação da serragem de eucalipto em diferentes temperaturas, a lignina agiu como um aglutinante natural, formando pontes sólidas entre as partículas do material em temperaturas superiores à 140°C. A transição vítrea encontrada para a lignina da serragem de eucalipto foi da ordem de 135°C. Em conclusão, as variáveis do material e do processo de densificação influenciaram nos mecanismos de ligação, afetando as propriedades da serragem de madeira densificada. Os principais mecanismos de ligação encontrados na serragem de madeira densificada foram interações intermoleculares e pontes sólidas.<br>Making biomass available for investments in biofuels, chemicals and materials, some undesirable properties as high moisture content and low density must be corrected. One solution to these problems would be densification of biomass. The densification process of biomass and waste materials, such as briquetting and pelletizing, are well known and used, however, there is no consensus about the connection mechanism occurs between the particles of the densified biomass and the influence of the variables of raw material and densification process has on them. Understanding the connection mechanism between the particles of the densified biomass is critical in determining the parameters of the raw material and the densification process, as well as the tests that should be performed to measure the quality of densified product. This study aimed to analyze the effect of varying the material and the densification process of sawdust in the densified product features and their influence on the binding mechanism between the particles of the material. The material in this work was the sawdust Eucalyptus sp. It was analyzed the effect of the material moisture content and temperature of the densification process in the density and mechanical strength of the densified product, but also the influence of the chemical composition of sawdust on the glass transition of the material. The eucalyptus sawdust was characterized by thermogravimetric analysis (TGA), chemical analysis and Fourier transform infrared spectroscopic (FTIR). The characterization of densified sawdust was performed by bulk density, volumetric expansion, compression mechanical testing, scanning electron microscopy (SEM), optical microscopy (OM), mass spectrometry of secondary ions time of flight (ToF-SIMS) and dynamical mechanical analysis (DMA). The results showed that without the heat densification process, the ideal moisture content eucalyptus sawdust was about 10%, favoring the intermolecular forces between particles of the material. In eucalyptus sawdust densification at different temperatures, lignin acted as a natural binder to form solid bridges between particles of the material at temperatures higher than 140°C. The glass transition temperature of the lignin found to eucalyptus sawdust was of the order of 135°C. In conclusion, the variables of material and densification process influenced the binding mechanism affecting the properties of the densified wood sawdust. The main binding mechanism found in densified wood sawdust were intermolecular interactions and solid bridges.

Die universelle Verwendung von Holz wurde durch die Entwicklung moderner lignozellulosefreier Werkstoffe in den letzten Jahrzehnten zurückgedrängt. Anisotropie und Inhomogenität, geringe Dauerhaftigkeit und große Streuung prägen die ingenieurtechnische Wahrnehmung von Holz. Mit der Einführung und Adaption neuer Technologien zur Verarbeitung von Holz wurden materialspezifische Nachteile verringert und definierte, kontinuierlich reproduzierbare Eigenschaften umsetzbar. Trotzdem werden heute im Wesentlichen zwei Verarbeitungsverfahren für Holz genutzt: Schneiden und Kleben. In der vorliegenden Arbeit wurde ein Verfahren zur Umformung nach DIN 8582 untersucht: die thermo-hygro mechanische Verdichtung mit anschließendem Gesenkbiegen und Tiefziehen. Der Schwerpunkt der durchgeführten Untersuchungen lag auf der Ausrichtung der Holzfaser senkrecht zur Umformung und stützte sich folgerichtig auf die Patente DE 102 24 721 „Formteil aus Holz und Verfahren zu seiner Herstellung“ und DE 502 08 785 „Profil aus Holz und Verfahren zu seiner Herstellung“, deren Hauptmerkmal die Verdichtung und Umformung unter Nutzung der Rückerinnerung für technische Formholzelemente darstellt. In der Arbeit wurden somit die Rohdichteverteilung und das Spannungs-Dehnungs-Verhalten während der Verdichtung, Rückerinnerung und Umformung untersucht. Einen breiten Raum nahmen die Ermittlung der Materialkennwerte von Pappel (Populus sp.), Kiefer (Pinus silvestris L.), Balsa (Ochroma boliviana R.), Buche (Fagus sylvatica L.) und Linde (Tilia sp.) hinsichtlich der Querzugfestig- und Steifigkeit ein. Es erfolgten Messungen zum Verdichtungsverhalten und zur Rückerinnerung von Kleinprobekörpern sowie die Untersuchung von uni- und biaxial verdichteten Platten bezüglich der eingebrachten Verformung in Betrag und Verteilung. Es wurde eine Wichtung der Einflußgrößen Holzfeuchtigkeit, Temperatur, Jahrringlage und Holzart vorgenommen. In der Auswertung wurden Möglichkeiten zur Manipulation einzelner Parameter betrachtet. Die Erfassung der neutralen Faser, sowie der Zug- und Druckzonen am beanspruchten Probekörper lies Rückschlüsse auf das Materialverhalten bei der Umformung zu. Für die Berechnung der Probekörpergeometrie wurde ein Dehnungsverhältnis (Zug/Druck) von 70% zu 30% zu Grunde gelegt. Im zweiten Teil der Arbeit wurden die technologischen Parameter beim Übergang vom Labormaßstab zur industriellen Anwendung, unter besonderer Beachtung der praktischen Aspekte der Herstellung von nachformbaren Massivholzplatten, beschrieben. Die Rasterfeldanalyse (GSA-Grid Strain Analysis) ermöglichte eine Abschätzung der Umformungsgrenzen von biaxial verdichteten Hirnholzplatten und deren Bewertung in einem FLD (Forming Limit Diagram). Es wurden Zug- und Tiefungsversuche in Anlehnung an Nakajiama (DIN EN ISO 12004-2) zur Charakterisierung der 3D-Formbarkeit, der Bestimmung des Umformgrades phi und der Versagensgrenzen zur fehlerfreien Herstellung eines Ellipsoidenelementes aus biaxial verdichteten Hirnholzelementen durchgeführt. Die Materialdehnungen betrugen mehr als 25%. Im Ergebnis der technologischen Umsetzung wurden 18 großformatige, uniaxial verdichtete Massivholzplatten im Gesenkbiegeverfahren zu Profilen mit 300mm Durchmesser und 3m Länge für eine Windkraftanlage hergestellt.:Inhaltsverzeichnis Abkürzungs- und Formelverzeichnis 1 Einleitung 1.1 Gegenstand und Zielsetzung der Arbeit 1.2 Struktur und Lösungsweg 2 Stand der Wissenschaft und Technik 2.1.1 Materialgrundlagen 2.1.2 Anatomie des Holzes 2.1.3 Chemie des Holzes 2.1.4 Physik des Holzes 2.1.4.1 Dichteeinfluß 2.1.4.2 Feuchtigkeitseinfluß 2.1.4.3 Temperatureinfluß 2.1.4.4 Temperatur-Feuchtigkeits-Einfluß auf den Glasübergang (Tg) 2.1.4.5 Einfluß der Porosität 2.2 Holzmodifikation 2.2.1 Umformverfahren 2.2.2 Holzumformung 2.2.2.1 Umformung längs zur Faserrichtung 2.2.2.2 Umformung quer zur Faserrichtung 2.2.2.3 Umformung von porösen Material 3 Eigene Versuche: Material, Methoden und Verfahren 3.1 Vorgehen und Arbeitsschritte 3.2 Materialien 3.2.1 Holz 3.2.1.1 Allgemein 3.2.1.2 Kleinproben 3.2.1.3 Großproben 3.2.1.4 Plattenherstellung 3.2.2 Thermo-hygro-mechanische Umformung (THMU) von Holz 3.2.2.1 Plastifizieren 3.2.2.2 Verdichtung (thermo-mechanisch) 3.2.2.3 Umformung (thermo-hygro mechanisch) 3.2.2.4 Fixierung 3.2.3 Textile Strukturen 3.2.4 Klebstoffe 3.2.4.1 Druckscherversuche DIN EN 386 3.2.4.2 Biegeversuche quer zur Faser in Anlehnung an DIN 52186 (1978) 3.2.4.3 Delaminierungsversuche (DIN EN 391) uniaxial verdichteter Platten 3.2.4.4 Delaminierungsversuche biaxial verdichteter Hirnholzplatten 3.3 Verfahren der Verdichtung und Umformung 3.3.1 Verdichtung 3.3.1.1 Vorrichtungen 3.3.1.2 Prozeß 3.3.1.3 Einflußparameter auf die Verdichtung 3.3.2 Umformung - Technologie 3.4 Methode 3.4.1 Rohdichtebestimmung nach DIN 52182 3.4.2 Feuchtigkeitsbestimmung nach DIN 52183 3.4.3 Temperaturbestimmung 3.4.4 Querzugversuch nach DIN EN 408 3.4.5 Quelldruckversuch 3.4.6 Verdichtung (Compression set) und Rückerinnerung (Recovery set) 3.4.7 Bestimmung der Lage der neutralen Faser 3.4.8 Tiefungsversuch in Anlehnung an DIN ISO 20482 4 Ergebnisse 4.1 Rohdichtemessung 4.2 Quelldruck 4.3 Querzug 4.4 Verdichtung und Rückerinnerung von Kleinproben 4.4.1 Uniaxiale Umformung 4.4.2 Diskussion 4.4.3 Biaxiale Verformung 4.4.4 Diskussion 4.5 Rückerinnerung und Umformung von Plattenprobekörpern 4.5.1 Prüfung ausgewählter Klebstoffeigenschaften an verdichteten Platten 4.5.1.1 Betrachtungen zur Klebstoffauswahl 4.5.1.2 Druckscherversuche nach DIN EN 386 4.5.1.3 Biegeversuche quer zur Faser in Anlehnung an DIN EN 310 (1993) 4.5.1.4 Delaminierungsversuche mit unidirektional verdichteten Platten 4.5.1.5 Delaminierungsversuche mit bidirektional verdichteten Platten 4.5.1.6 Diskussion 4.5.2 Umformung von verdichteten Platten 4.5.2.1 Bestimmung neutrale Faser 4.5.2.2 Einfluss des Verdichtungsgrades 4.5.2.3 Einfluss der Plattendicke 4.5.2.4 Diskussion 4.5.2.5 Uniaxiale Umformung großformatiger Platten 4.5.2.6 Biaxiale Umformung großformatiger Platten 4.5.2.7 Diskussion 5 Zusammenfassung und Ausblick 6 Literaturverzeichnis 7 Anhang<br>Over the last decades, the general use of wood was displaced by the development of non-lingo-cellulosic materials. Today’s engineering perception of wood is characterized by anisotropy and inhomogeneity, low durability, and large variance. The implementation and adaption of new technologies in wood processing reduced specific disadvantages in material and designs and allowed to achieve continuously reproducible properties. Despite these advances, today two main processing methods are used for wood: sawing and gluing. In the presented work, a forming process has been investigated according to DIN 8582: thermo-hydro mechanical densification with press brake bending and deep drawing. The key aspect of this studies was focused on the wood fiber direction perpendicular to the bending line. It was based on the patents DE 102 24 721 „ Wood Profile and Method of the Production of the Same” and DE 502 08 785 „Wood Profile and Process of the Production of the Same”. The major interest was determined by densification and forming of wood structure profiles utilizing recovery. In the presented study, density distribution and stress-strain behavior was analyzed during densification, recovery, and forming process. A major part of the work was the evaluation of material properties of poplar (Populus sp.), pine (Pinus silvestris L.), balsa (Ochroma boliviana R.), beech (Fagus sylvatica L.) and lime (Tilia sp.) regarding their strength and stiffness. Furthermore, tests were performed evaluating the imposed plastic deformations with regard to amount and distribution on small test cubes (60 by 60 by 50 mm³) and uni- and biaxial densified boards. Parameters like wood moisture, temperature, annual ring direction and wood species as well as a description of the different impact on the forming results were assessed. The analysis of neutral axis as well as the tension- and compression zones on the tested specimens allowed for conclusions on the wood behavior during the forming process. The calculation of specimens geometry was made with the strain relationship (tension / compression) of 70 to 30 percent. The technological parameters were described by up-scaling from laboratory to industrial application with special focus on the practical aspects of producing moldable end-grain boards. The grid strain analysis (GSA) enabled an estimation of forming limits on biaxial densified end grain boards in an FLD (forming limit diagram). Tension and deep drawing tests according to Nakajiama (DIN EN ISO 12004-2) were carried out to characterize the 3D-moldability, to determine the degree of deformation and the failure limit by producing ellipsoid elements on biaxial densified end grain boards. A material strain of more than 25% was achieved. Using press brake bending, 18 wood profiles were manufactured with a diameter of 300mm and a length of 3000mm. The implementation of described wood profiles using uniaxial densified large boards was deployed in a wind power plant.:Inhaltsverzeichnis Abkürzungs- und Formelverzeichnis 1 Einleitung 1.1 Gegenstand und Zielsetzung der Arbeit 1.2 Struktur und Lösungsweg 2 Stand der Wissenschaft und Technik 2.1.1 Materialgrundlagen 2.1.2 Anatomie des Holzes 2.1.3 Chemie des Holzes 2.1.4 Physik des Holzes 2.1.4.1 Dichteeinfluß 2.1.4.2 Feuchtigkeitseinfluß 2.1.4.3 Temperatureinfluß 2.1.4.4 Temperatur-Feuchtigkeits-Einfluß auf den Glasübergang (Tg) 2.1.4.5 Einfluß der Porosität 2.2 Holzmodifikation 2.2.1 Umformverfahren 2.2.2 Holzumformung 2.2.2.1 Umformung längs zur Faserrichtung 2.2.2.2 Umformung quer zur Faserrichtung 2.2.2.3 Umformung von porösen Material 3 Eigene Versuche: Material, Methoden und Verfahren 3.1 Vorgehen und Arbeitsschritte 3.2 Materialien 3.2.1 Holz 3.2.1.1 Allgemein 3.2.1.2 Kleinproben 3.2.1.3 Großproben 3.2.1.4 Plattenherstellung 3.2.2 Thermo-hygro-mechanische Umformung (THMU) von Holz 3.2.2.1 Plastifizieren 3.2.2.2 Verdichtung (thermo-mechanisch) 3.2.2.3 Umformung (thermo-hygro mechanisch) 3.2.2.4 Fixierung 3.2.3 Textile Strukturen 3.2.4 Klebstoffe 3.2.4.1 Druckscherversuche DIN EN 386 3.2.4.2 Biegeversuche quer zur Faser in Anlehnung an DIN 52186 (1978) 3.2.4.3 Delaminierungsversuche (DIN EN 391) uniaxial verdichteter Platten 3.2.4.4 Delaminierungsversuche biaxial verdichteter Hirnholzplatten 3.3 Verfahren der Verdichtung und Umformung 3.3.1 Verdichtung 3.3.1.1 Vorrichtungen 3.3.1.2 Prozeß 3.3.1.3 Einflußparameter auf die Verdichtung 3.3.2 Umformung - Technologie 3.4 Methode 3.4.1 Rohdichtebestimmung nach DIN 52182 3.4.2 Feuchtigkeitsbestimmung nach DIN 52183 3.4.3 Temperaturbestimmung 3.4.4 Querzugversuch nach DIN EN 408 3.4.5 Quelldruckversuch 3.4.6 Verdichtung (Compression set) und Rückerinnerung (Recovery set) 3.4.7 Bestimmung der Lage der neutralen Faser 3.4.8 Tiefungsversuch in Anlehnung an DIN ISO 20482 4 Ergebnisse 4.1 Rohdichtemessung 4.2 Quelldruck 4.3 Querzug 4.4 Verdichtung und Rückerinnerung von Kleinproben 4.4.1 Uniaxiale Umformung 4.4.2 Diskussion 4.4.3 Biaxiale Verformung 4.4.4 Diskussion 4.5 Rückerinnerung und Umformung von Plattenprobekörpern 4.5.1 Prüfung ausgewählter Klebstoffeigenschaften an verdichteten Platten 4.5.1.1 Betrachtungen zur Klebstoffauswahl 4.5.1.2 Druckscherversuche nach DIN EN 386 4.5.1.3 Biegeversuche quer zur Faser in Anlehnung an DIN EN 310 (1993) 4.5.1.4 Delaminierungsversuche mit unidirektional verdichteten Platten 4.5.1.5 Delaminierungsversuche mit bidirektional verdichteten Platten 4.5.1.6 Diskussion 4.5.2 Umformung von verdichteten Platten 4.5.2.1 Bestimmung neutrale Faser 4.5.2.2 Einfluss des Verdichtungsgrades 4.5.2.3 Einfluss der Plattendicke 4.5.2.4 Diskussion 4.5.2.5 Uniaxiale Umformung großformatiger Platten 4.5.2.6 Biaxiale Umformung großformatiger Platten 4.5.2.7 Diskussion 5 Zusammenfassung und Ausblick 6 Literaturverzeichnis 7 Anhang

&lt;p&gt;The lightness and thermal performances of timber has led designers to consider using it for urban densification and to make it the key for a more sustainable and affordable construction industry.&lt;/p&gt;&lt;p&gt;This project of a timber-framed high-rise building will become one of the tallest in Switzerland to adopt a wooden construction, using a mix of two types of manufactured wood: cross-laminated timber (CLT) for structural walls and glue-laminated timber (a.k.a. glulam) combined to an upper concrete layer linked with screws for the slabs. The use of timber sourced from local forest is considered by the engineers because its abundance in Switzerland.&lt;/p&gt;&lt;p&gt;The concrete layer is needed to reach a high level of acoustic performance and to efficiently create horizontal diaphragms for earthquake resistance. It also enables the reduction of the thickness of the complex. The lower wooden surfaces with warm natural appearance are visible from the rooms, as well as the vertical surfaces of the CLT wall supporting them.&lt;/p&gt;&lt;p&gt;The project reveals the complexity for timber structures to simultaneously comply with regulations concerning structural, fire safety, acoustical and earthquake-resistance performances. Building Information Modeling (BIM) allows excellent technical installations coordination to reach a high degree of prefabrication.&lt;/p&gt;