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  • 1.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Salin, Jarl-Gunnar
    Application of percolation modelling on end-grain water absorption in aspen (Populus tremula L.)2011Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, Vol. 6, nr 3, 112-118 s.Artikel i tidskrift (Refereegranskat)
  • 2.
    Alfredsen, Gry
    et al.
    Norwegian Forest and Landscape Institute, Norway.
    Bollmus, Susanne
    Georg-August-University of Göttingen, Germany.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Basidiomycete colonization of Scots pine sapwood quantified by qPCR and TGA2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Scots pine (Pinus sylvestris L.) is an important softwood species in Northern Europe and is frequently used as material for various wood protection systems. In Europe, EN 113 is the standard basidiomycete laboratory durability test method, using mass loss as evaluation criteria. In this paper quantitative real-time PCR (qPCR) and thermogravimetric analysis (TGA) was used to characterize colonization by basidiomycetes in Scots pine sapwood, but also to learn more about the EN 113 test. Two different wood sample sizes were tested. For Gloeophyllum trabeum the largest sample size gave the highest mass loss, while for the smallest samples Trametes versicolor gave the highest mass loss. As expected, fungal DNA content and mass loss in Scots pine sapwood samples decayed by G. trabeum became higher with increasing incubation time of 16 weeks. More unexpectedly, the T. versicolor DNA content in Scots pine sapwood samples was highest at the start of the incubation period and declined during the incubation period, while mass loss increased during the 28 week incubation period. The fungal colonization in the side and middle of EN 113 samples was tested. Highest DNA contents of G. trabeum were measured in the sides during 16 weeks of incubation. The T. versicolor DNA content was higher or similar in the side compared to the middle of the samples until week 20. For weeks 20 and 22 the DNA content was higher in the middle than in the sides, while for the remaining incubation period (weeks 24, 26 and 28) it was quite similar. TGA was shown to be a useful and fast method for chemical characterization of brown rot decayed wood, but cannot be used for white rot decayed wood. For T. versicolor moisture and fungal DNA explained most of the variation in mass loss, while for G. trabeum moisture explained most of the variation in mass loss. 

  • 3.
    Taalas, Saara L.
    et al.
    Linnéuniversitetet, Fakultetsnämnden för ekonomi och design, Ekonomihögskolan, ELNU.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Bridging life at home and sustainable production.2011Ingår i: Rediscovering Wood: The Key to a Sustainable Future, 2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Dr Saara Taalas and Dr Dick Sandberg presented the relevance of looking in more detail the consumption patterns that will influence relationships with material culture. The consumption patterns change over time suiting to everyday life of that time at a locality. For instance, in Nordic countries, the same forests that served livelihood of people in the past are now important centres for recreation- a change of dimension from livelihood to sports. Thus, the relations with forests have dramatically changed. Many people are now secondary stakeholders (using its products) than directly depending on it for livelihood as people did 100 years ago. The same happened to the relation with the material originating from the forests. For instance, in Sweden firewood dominated harvest from forests (40%) in 1900, but is less than 8 % now. On the contrary, pulpwood that was just 5 % of the harvest in 1900 constitutes now 44 %. Only sawmilling remained relatively the same. Visions for Finnish bio economy business levels reflect the increasing relevance of living trees and bio-energy in future. The wood products will be there but the requirements will change- from volume to specific requirements on properties (e.g. shape stability). The tactile of part of wood see more money but the traditional paper and pulp products are likely to lose its relevance in Northern Europe because of high prices, changing markets and long rotation of forest trees.

    Thus, the pulp mills diversify with new products (e.g. textiles). Innovation in new processes will drive ways for new wood use in future (e.g. polymers and chemicals, bioenergy etc). Prioritising purpose will determine wood’s value. For example, using wood for bioenergy (which gains relevance in Northern Europe) might negatively influence many other business levels. Increasing business value should be given emphasis as trees could be sold 100 times through process innovations.

  • 4. Braovac, Susan
    et al.
    Fackler, Karin
    Bader, Thomas K.
    Ters, Thomas
    Chemical Composition of the Archaeological Oak Wood from the Oseberg Ship2011Ingår i: Cultural Heritage Preservation.EWCHP - 2011: Proceedings of the European Workshop on Cultural Heritage Preservation. Berlin, Germany, September 26 to 28, 2011, Fraunhofer IRB Verlag, 2011, 156-163 s.Konferensbidrag (Refereegranskat)
  • 5.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Johansson, Jimmy
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Contact free measurement of complex shapes in the wood industry2011Ingår i: Mechano-chemical transformations of wood during THM processing / [ed] Parviz Navi and Andreas Roth, Biel, Switzerland: Bern University of Applied Sciencs, Architecture, Wood and Civil Engineering , 2011, 143-144 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is an increasing need to update and correct information about product geometry in the wood manufacturing industry. Changes in machinery or personnel can be the cause of that need. Manual measurement takes time and diff erent ways of digitizing the geometry of the products have therefore been developed.

    In this study, two methods (3D-coordinate measurement and optical scanning) have been tested together in order to determine the position of a product in relation to the processing machine, and to optically scan the product geometry. The aim was to identify and evaluate methods to digitize product geometry into a CAD-model for the wood industry. Th e seat shell measured was fitted in the CNC-machine where the processing later would be performed.

    The methodology used has made it possible to create a CAD-model from the physical model. Based on the experience from this methodology, it would be recommended to continue by creating of a tool that minimizes the need for after processing, i.e. the adjustment of certain coordinates manually.

  • 6. Pearson, Hamish
    et al.
    Gabbitas, Brian
    Ormarsson, Sigurdur
    Creep and Mechanosorption of Wood at High Temperature2011Ingår i: Thermo-Hydro-Mechanical Wood Behaviour and Processing, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Creep and mechanosorptive behaviour of wood are two important phenomena that occur in wood during thermo-hygro-mechanical processing such as drying or heat treatment. However, these variables are inherently difficult to study and quantify experimentally due to equipment design difficulties and material behaviour complexity. For example, for elevated temperatures, pressure rated equipment is required for humidities up to 100% and experimental design must account for any overlap between creep and mechanosorption at elevated temperatures and moisture contents. A study is described in which the material properties of creep and mechanosorption of radiata pine (Pinus radiata D.Don) were experimentally obtained and statistically modelled as functions of temperature, moisture content and stress (Pearson et al 2004).

    Tensile creep and mechanosorption displacement data was collected over time for tangential grain radiata pine sapwood at temperatures between 70 and 150°C for a variety of moisture contents and applied stress. A full description of three-dimensional mechanical behaviour for a single wood species is complex in that it requires all combinations of tension, compression, and shear behaviour for the three grain directions, for heartwood and sapwood, for all elements of the total strain equation and as functions of the main control variables temperature, moisture content and stress. This study reduced as many of these variables as possible to focus on equipment design and development and to keep experiments within achievable limits. Radiata pine was used because it is an important plantation grown species in New Zealand.Sapwood was used because of the high recovery rate, the tangential grain direction was chosen as it exhibits the greatest shrinkage range compared to longitudinal and radial directions and tension testing was used as it avoids buckling failure and therefore yields more uniform results. Matched samples were taken from one representative tree for which as much wood quality information as possible was recorded. The wood quality information was then used as a covariate during statistical analyses of the results. The use of samples from one tree instead of many also helped to evaluate the efficiancy and accuracy of the equipment that was specially designed for this work.

    For the creep studies the moisture content was kept constant at varying levels but for the mechanosorption studies the moisture content was varied cyclically. A modified central composite experimental design was used for both the creep and mechanosorption studies to reduce the number of experiments. Wood moisture content was controlled using a high temperature dew point sensor and a preliminary set of experiments was performed to quantify the relationship between dew point, humidity and equilibrium moisture content whilst under pressure. The results were then applied to the central composite design. The same levels of temperature were used in both the creep and mechanosorption tests but applied stress was significantly reduced for the mechanosorption tests compared to the creep tests in order to reduce the presence of creep.

    Both creep and mechanosorption tests were performed in a modified Moldrup variable pressure kiln. Tensile samples were connected to a specifically designed and constructed tensile rig that was able to accommodate ten samples at a time. The rig included an external jack to enable either weight removal or application during operation in order to control applied stress. The whole unit, including the Moldrup kiln was controlled through a specifically developed control and data acquisition system called MechanoSpec.

    As expected, creep results revealed a dramatic increase in creep strain for higher temperature, stress or moisture content. Creep results were best described using a power law which interestingly indicated the lack of a creep limit at higher temperatures. The amplitude response of the creep power law equation was found to be primarily dependent on stress, temperature, moisture content and cycle number. Cycle number related to the number of times a load was added or removed. Stress and temperature were best described by an exponential term, which showed that the creep strain rapidly increased with an increase in either of these variables, whilst MC was best described by a power term. The power term could be expressed as a linear function of stress. Interestingly a small degree of morphing between the instantaneous elastic and creep curves was apparent at higher temperatures. This was due to curvature in the elastic region for high, compared to low temperature results. A greater displacement was statistically recorded for the first cycle of loading and unloading compared to all succeeding cycles. This may have been due to irreversible plastic deformation but it is interesting to note there may be a limit as later cycles usually reached the same level of displacement. The overall coefficient of determination for the statistical creep equation was 0.740.

    Mechanosorption displacement magnitude results were best described using a common low temperature relationship where mechanosorptive displacement is a function of the absolute value of moisture change and stress. The curvature to reach the mechanosorption displacement was modelled using an exponential function containing temperature and mean moisture content terms. However, mechanosorption displacement was not found to be dependent on temperature but the results revealed that an opposing phenomenon to mechanosorption occurred due to reduced hygroscopicity. This was labelled as thermo-sorptive-aging and only occurred when a change in moisture took place which was different to the change in moisture when drying from green without adsorption. Thermo-sorptive-aging was a function of temperature and moisture content oscillation cycle number and affected the final amplitude level of EMC, but not the rapidity to which the final amplitude was reached. The cycle number was the number of times a moisture change had been effected through a setpoint change and required some form of moisture content steady state to have been reached before successive changes were made. The thermo-sorptive-aging effect was thought to be due to the loss of hydrogen bonding sites in cellulose that occurred every time bound water and cellulose bonds were alternatively broken and reformed through wetting and rewetting. It is likely such a phenomenon could be used to reduce drying times and internal checking through some sort of bond shuffling, where wood structure is massaged during oscillatory drying. This would theoretically allow as much of the wood structure as possible to be gently morphed into a modified form without placing excessive stress on the remaining original crystallite bound water bonds that occur when drying without adsorption. The overall coefficient of determination for the statistical creep equation was 0.880.

  • 7.
    Fagerberg, Nils
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Dags att diskutera lönsamheten i kontinuitetsskogsbruk2011Ingår i: Jord & Skog, 2-2 s.Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 8.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Alfredsen, Gry
    Norwegian Forest and Landscape Institute, Norway.
    Bollmus, Susanne
    Georg-August-University of Göttingen, Germany.
    Decrease of stiffness properties of degraded wood predicted by means of micromechanical modeling2011Ingår i: Proceedings of the International Research Group on Wood Protection IRG/WP 11-40570, International Research Group on Wood Protection , 2011, 2-15 s.Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Wood exhibits a highly anisotropic mechanical behavior due to its heterogeneous microscopic structure and composition. Its microstructure is organized in a strictly hierarchical manner from a length scale of some nanometers, where the elementary constituents cellulose, hemicelluloses, lignin, and extractives are found, up to a length scale of some millimeters, where growth rings composed of earlywood and latewood are observed. To resolve the microscale origin of the mechanical response of the macro-homogeneous but micro-heterogeneous material wood, micromechanical modeling techniques were applied. They allow for prediction of clear wood stiffness from microstructural characteristics. Fungal decay causes changes in the wood microstructure, expressed by modification or degradation of its components. Consequently, macroscopic mechanical properties are decreasing. Thus, in the same manner as for clear wood, consideration of alterations of wood in a micromechanical model allows predicting changes in the macroscopic mechanical properties. This contribution covers results from an extensive experimental program, where changes in chemophysical properties and corresponding changes in the mechanical behavior were investigated. For this purpose, Scots pine (Pinus sylvestris L.) sapwood samples were measured in the reference condition, as well as degraded by brown rot (Gloeophyllum trabeum) or white rot (Trametes versicolor). Stiffness properties of the unaffected and the degraded material were not only measured in uniaxial tension tests in the longitudinal direction, but also in the three principal material directions by means of ultrasonic testing. The experiments revealed transversal stiffness properties to be much more sensitive to degradation than longitudinal stiffness properties. This is due to the degradation of the polymer matrix between the cellulose fibers, which has a strong effect on the transversal stiffness. On the contrary, longitudinal stiffness is mainly governed by cellulose, which is more stable with respect to degradation by fungi. Consequently, transversal stiffness properties or ratios of normal stiffness tensor components may constitute suitable durability indicators. Subsequently, simple micromechanical models, as well as a multiscale micromechanical model for wood stiffness, were applied for verification of hypotheses on degradation mechanisms and model validation.

  • 9.
    Adamopoulos, Stergios
    et al.
    Georg-August-University Goettingen, Germany ; Technological Educational Institute of Larissa, Greece.
    Xie, Yanjun
    Georg-August-University Goettingen, Germany.
    Militz, Holger
    Georg-August-University Goettingen, Germany.
    Distribution of blue stain in untreated and DMDHEU treated Scots pine sapwood panels after six years of outdoor weathering2011Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 69, nr 2, 333-336 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface coating and bulk treatment of wood are two effective measures which can, individually or conjointly, protect exterior wood from deterioration. This paper reports on the blue stain attack in coated wood, untreated and modified with DMDHEU, after six years of natural exposure.

  • 10.
    Götmark, Frank
    et al.
    University of Gothenburg.
    Schott, Kaitlin Muir
    University of Alberta, Canada.
    Jensen, Anna M.
    Swedish University of Agricultural Sciences.
    Factors influencing presence-absence of oak (Quercus spp.) seedlings after conservation-oriented partial cutting of high forests in Sweden2011Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, Vol. 26, nr 2, 136-145 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We studied occurrence of oak seedlings (Quercus robur L. and Q. petraea Liebl.) in 11 semi-natural oak-rich temperate forests in south Sweden after partial cutting (mean harvest; 26% of basal area). Earlier studies show that canopy openness is positively correlated with oak seedling performance. We used 20 pairs of subplots in each forest, with and without oak seedlings and matched with respect to canopy openness, to analyse other factors associated with seedling establishment and growth. The height of the ground layer (herbs and woody plants) had negative influence, i.e. higher height was associated with reduced probability of seedling occurrence. Higher soil water content had positive influence on seedling occurrence. Protection of seedlings by e.g. Rubus spp., twigs or dead wood was associated with lower seedling occurrence, but seedlings that did establish there tended to be taller. Type of ground vegetation and species composition did not differ between subplots with and without oak seedling. Thus, after conservation-oriented partial cutting of closed canopy high forests, increasing height of the ground vegetation disfavours oak seedlings (independent of canopy openness). High soil moisture favours oak seedlings, as does protected microsites for seedlings that can maintain high growth rate among their competitors.

  • 11.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    From lignin to spruce: Poromechanical upscaling of wood strength2011Ingår i: 2010 MRS Fall Meeting: Symposium V/NN/OO/PP – Soft Matter, Biological Materials and Biomedical Materials—Synthesis, Characterization and Applications / [ed] A.J. Nolte, K. Shiba, R. Narayan, D. Nolte, Warrendale, Pennsylvania, USA: Materials Research Society, 2011, Vol. 1301, 75-80 s.Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Wood strength is highly anisotropic, due to the inherent structural hierarchy of the material. In the framework of a combined random-periodic multiscale poro-micromechanics model, we here translate compositional information throughout this hierarchy into the resulting anisotropic strength at the softwood level, based on “universal” elastic properties of cellulose, hemicelluloses, and lignin, and on the shear strength of the latter elementary constituent. Therefore, derivation of the elastic energy in a piece (representative volume element – RVE) of softwood, stemming from homogeneous macroscopic strains prescribed in terms of displacements at the boundary of the RVE and from pressure exerted by water filling the nanoporous space between the hemicelluloses-lignin network within the cell walls, with respect to the shear stiffness of lignin, yields higher order strains in the lignin phase, approximating micro-stress peaks leading to local lignin failure. Relating this (quasi-brittle) failure to overall softwood failure (or strictly speaking, elastic limit of softwood) results in a macroscopic microstructure-dependent failure criterion for softwood. The latter satisfactorily predicts the biaxial strength of spruce at various loading angles with respect to the grain direction. The model also predicts the experimentally well-established fact that uniaxial tensile and compressive strengths, as well as the shear strength of wood, depend quasi-linearly on the cell water content, but highly nonlinearly on the lumen porosity. 

  • 12.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Mai, C
    From wood fibre modification to paper technology: properties of fibres modified with DMDHEU and glutaraldehyde2011Ingår i: 3rd biennial International Fibre Engineering Conference, 24 – 26 May, Barcelona, Spain, 2011Konferensbidrag (Övrigt vetenskapligt)
  • 13.
    Hu, Min
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Johansson, Marie
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Olsson, Anders
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Bengtsson, Charlotte
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Brandt, Anders
    University of Southern Denmark, Denmark.
    Grading of sawn timber using the vibration technique: locating imperfections based on flexural mode shapes2011Ingår i: 17th international nondestructive testing and evaluation of wood symposium / [ed] Ference Divos, Sopron, Hungary: University of West Hungary , 2011, 269-276 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present study aims at investigating the potential of using mode shape or mode shape curvature (MSC) for detecting defects in wooden beams. It includes modal analysis, Finite Element (FE) modeling and visual scanning. An FE model was created to investigate the effect of defects of different size and location on the mode shape/MSC. The mode shape/MSC showed a good potential to be used for finding defects. An experimental study on 17 boards of Norway spruce, dimensions of 50×150×3900 mm, was conducted using experimental modal analysis. The findings reveal that: (1) the mode shape/MSC studied in the FE-model could be used to locate defects, (2) the method is very sensitive to measurement noise and it requires an accurately measured mode shape, (3) an error analysis shows that it is not possible to achieve the accuracy needed using accelerometers.

  • 14.
    Nilsson, Bengt
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Blom, Åsa
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Hanteringens inverkan på skogsbränslets barrandel och fukthalt: – en jämförande studie mellan grönrisskotning och traditionell brunrisskotning av grot2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    I föreliggande studie har vi analyserat hur grotens barrandel påverkas av grönrisskotning jämfört med traditionell brunrisskotning. En hypotes har varit att den traditionella brunrisskotningen inte medför så stort barravfall som man tidigare trott. Om grönrisskotning skulle accepteras skulle det öppna möjligheter för nya tekniker, minskade kostnader, kortare ledtider samt ett större totalt uttag från den enskilda avverkningstrakten. Observera att även grönrisskotning ger ett torkat bränsle och inte skall förväxlas med färsk grot. Bestämning av fraktionsfördelning och fukthalt har genomförts i det material som levereras till den energiomvandlande industrin i anslutning till flisning av groten.

    Resultaten visar att grönrisskotning medför en kraftig avbarrning och innehåller betydligt mindre andel barr än färsk grot. Resultatet visar även att traditionellt brunrisskotad grot innehåller en hel del barr. I praktiken innebär det att grönrisskotad grot innehåller dubbelt så mycket barr (ca 8 % av grotens total torrmassa) som den traditionellt brunrisskotade (ca 4 % av grotens total torrmassa) vid leverans till den energiomvandlande industrin. Både grönrisskotning och brunrisskotning ger en tillfredsställande torkning och resultatet visar att det endast skiljer 5 procentenheter i medelfukthalt mellan grönrisskotad (36 %) för och brunrisskotad (31 %) grot.

    Det har även kunnat konstaterats att groten behöver ligga större delen av sommaren i små processorhögar för att uppnå den rekommenderade avbarrningen. All grot som skotas ihop tidigare än augusti månad är därmed att betrakta som mer eller mindre grönrisskotad. Slutsatsen blir att en stor del av den grot som idag levereras till den energiomvandlande industrin snarare är grönrisskotad än brunrisskotad och innehåller ca 5–10 % barr.

  • 15.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Johansson, Jimmy
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Improving the performance of bended laminated veneer products2011Ingår i: Mechano-chemical transformations of wood during THM processing / [ed] Parviz Navi and Andreas Roth, Biel, Switzerland: Bern University of Applied Sciencs, Architecture, Wood and Civil Engineering , 2011, 147-148 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Laminated bending of veneers mean that dried, thin veneers or thin wood sheets are glued together under influence of pressure and eventually increased temperature. At the same time the product is given its desired shape, most often curved. This thermo hydro mechanical process offers several benefits. For example thick bends of small radiuses of any species of wood may be formed and poor quality wood containing knots, splits and other defects may be utilised. Laminated bends can usually be set more readily and made to conform better to the shape of the form than similar bends of solid wood. Further no softening treatment is generally required before the pieces are bent. However, there are also disadvantages e.g. more technical skill and better equipment are usually required than for solid wood bending. The presence of glue may be somewhat detrimental to the machines used for the final cleaning up of the bent pieces. Further the glue lines which are usually visible on the sides may be an aesthetical unappreciated effect [1],[2].The quality of the laminated bended veneer products are obtained as an interaction between the process, the veneers and the glue [3]. In industries designing and producing these products it is of interest to obtain better understanding of how processing- and material parameters affect the product quality. With an improved understanding of the material and processing parameters it may be possible to increase the efficiency of wood utilisation and promote the development of new processes and products that manipulate the viscoelastic nature of wood. In particular the possibilities to obtain narrower radius of curvature and better possibilities of bending in more than one plane would be advantageous.This study has focused on the moisture content (MC) and the grain angle orientation in the veneers. These two specific aspects were assumed to have a great influence on spring-back and distortions of the laminated bended veneer products. Spring-back and distortions were therefore studied in separate tests where MC and the grain angle orientation was varied separately in manufactured laminated bended wood products. After manufacturing the products were exposed to variations in humidity and temperature whereupon the spring-back and distortions were measuredThree tests were performed. For the first and the second test a seat shell was selected as test product, figure 1a. To the third test another product was selected, figure 1b. This product was a small bookshelf. The company producing this shelf had experienced large problems considering distortions of this product. Further the product was very simple in shape with only one bend and therefore suitable for measurements.In the first test the influence of MC of the veneers was investigated. In the second and third test the influence of grain angle of the veneers was studied.For the study veneers of birch and beech were selected in the production. For the first and third study only birch veneers were used. The veneers were initially conditioned to equilibrium moisture contents (EMC) according to setups in different test groups. For the first study a test group was also built up from veneers taken directly out of production to study the industrial conditions. The seat shells in this test group contained veneers conditioned to EMC 4 %, except for the surface veneers that had been stored in the production hall. The humidity and temperature conditions in this room corresponded to MC 7 %.The manufacturing of the products were performed in industrial conditions. In the tests the products were built up from a number of veneers and the studied factors were varied between the veneers in a controlled manner.The results from the first test showed that the MC of the veneers influenced the spring-back and the distortions. A large moisture gradient between veneers and especially unsymmetrical placements of these in the construction were especially critical. The results from the second and third tests showed that grain angle deviation has large effect on the distortions of the products. Even a small grain angle deviation as in study two (5°) resulted in large problems with distortions. The study also showed that when crossing two or more veneers with deviating grain angles there were cases when these faults interacted and multiplied the distortions. In production grain angle deviations can be a result of inaccurate placement of the veneers during pressing, incorrect cutting of the veneers, inherent from the growth of the tree or a combination of these factors. Deviations of the grain angle were, however, shown to have only small effects on spring-back.

  • 16. Pearson, Hamish
    et al.
    Gabbitas, Brian
    Ormarsson, Sigurdur
    Instantaneous Wood Distortion under High Temperature Drying2011Ingår i: COST Action FP0904: Thermo-Hydro-Mechanical Wood Behaviour and Processing, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internal stresses develop in wood during moisture conditioning because of its hygroscopic properties and unequal shrinkage behaviour in the three grain directions. However, such stresses can be inherently difficult to detect. External wood distortion usually indicates the presence of internal stress but all stress may have been relieved through such distortion. Conversely, wood, which shows no external distortion, may still exhibit an internal stress imbalance which can lead to distortion after sawing. Stress effects associated with kiln drying can result in significant sawn lumber product degrade as a result of warping and checking.

    Two methods exist to assess internal stress in wood as a result of moisture change. The first method is direct measurement, as with prong and slices tests, and the second method is to model internal stress. Direct measurement assessments are usually unable to be performed during moisture conditioning and are invasive in that they lead to sample destruction. Conversely stress modeling is predictive and requires fundamental wood material properties and complex software to solve the mechanical equations in space and time.

    A work programme was initiated at Scion, New Zealand, with the overall goal of collecting high temperature (70 to 150ºC) material properties for use in modeling the stress developed in radiata pine during high temperature kiln drying. A key focus was also to design and develop equipment to accurately measure fundamental material properties required for such modeling. The study was designed to extend an earlier three dimensional distortion model developed by Ormarsson (2000) to predict drying stress in wood up to a temperature of 70°C where the total strain equation was assumed to consist of the summation of elastic, moisture-induced shrinkage, mechanosorptive and creep deformations. Each component of the total strain equation was studied separately with respect to the variables stress, time, temperature and moisture content using purpose designed equipment and the results combined in a finite element stress model.

    Experimental material property results for tangential grain, tensile, radiata pine (Pinus radiata D.Don) sapwood samples were combined into an instantaneous distortion model to predict stress or distortion as a function of temperature, moisture content and either external load or distortion. All samples were taken from one representative plantation tree from which wood quality information was obtained for a covariate analysis of the results. This included basic wood density, spiral grain, conic angle, and cardinal point mean microfibril angle which was obtained using SilviScan. Poissons' ratios were estimated from digital speckle photography experiments perfomed using an Aramis system at 20°C whilst the remaining compliance matrix variables such as shear moduli and moduli of elasticity for longitudinal and radial grain directions were estimated from published ratios.

    The distortion model architecture involved Python code for use as an input into Abaqus software with Fortran subroutines. For each study a moisture field output file, based upon the chosen constant temperature, was obtained for each geometric sample element and the results used as an input into the stress model. Stress model results were compared with representative experimental results from instantaneous, free shrinkage and mechanosorption studies.

    Results showed good agreement between the model and instantaneous elastic, free shrinkage and mechanosorption experimental results for tensile sample geometries, provided a 'thermo-sorptive-aging' effect was used to compensate for reduced hygroscopicity, if wood was alternately wet and re-wet in a cyclic fashion. A full board distortion model was then used to test the resultant stresses associated with wood that was dried to 5% moisture content followed by steaming to simulate final stress relief as implemented by industry. As expected, full board model results revealed the average stress in the longitudinal, radial and tangential directions to decrease after steaming, compared to drying with no steaming. Even though internal stresses from modelling were higher after steaming compared to only drying, total stress was improved. This theoretically caused less external distortion in a simple geometry like a board, although creep was not included in the simulations and may help to equalise internal stress further over time. Stress result profiles within the board agreed with earlier studies for two dimensional distortion by Chen et al (1997b).

    The three dimensional high temperature distortion model that was developed as part of this work is a valuable tool for distortion assessment compared to one- or two-dimensional models that are limited to a single plane. Future work will seek to optimise moisture conditioning schedules and thermo-hygro-mechanical treatments using the full board distortion model with full mechano-sorptive-creep analysis.

  • 17.
    Kifetew, Girma
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Nilsson, Jonaz
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Is it possible to constrain moisture movement of densified wood product mechanically?2011Ingår i: Mechano-chemical transformation of wood during THM processing / [ed] Navi, P. & Roth, A, Biel Switzerland: Bern University of Applied Sciencs, Architecture, Wood and Civil Engineering , 2011, 67-68 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Densification of wood in the transverse direction increases the density. One of the reasons for densifying wood is to produce high quality timber from timbers of low quality. However, densified wood shows an undesired behaviour, i.e. a tendency to return to its initial dimensions when it is subjected to heat and humidity, i.e. shape memory. There are several methods to overcome the problem of shape memory.

    This study uses a three-layered cross-laminated wood panel where one of the layers is of densified wood and the other two are of normal wood together these will mechanically restrain the shape memory of the densified layer.

    The study includes three stages:

    • Densification of clear wood in the radial direction
    • Manufacture of a three-layered cross laminated composite product with densified wood as a service layer
    • Testing of the shape stability when the composite was subjected to variations relative humidity (40-85 % RH at 20°)

    The result of this study reveals the significance of service to bottom layer thickness ratio on the shape stability of the cross laminated composite. Consequently, the performance and the shape stability of the cross laminated composite were significant when the service to bottom layer thickness ratio increases. Therefore, it appears feasible to disclose the appreciable degree of shape stability, hardness and wear resistance of the product. Accordingly, cross laminated composite can be considered as one of the promising mechanical methods for improving moisture movement of densified wood product.

  • 18. Palm, Johan
    et al.
    Karlsson, Reine
    Woxblom, Lotta
    Johansson, Jimmy
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Lönsamt lövträ: Affärsutveckling för lövträrelaterad tillverkningsindustri 2007-20102011Rapport (Övrigt vetenskapligt)
  • 19.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Karageorgos, Anthony
    Passialis, Costas
    Chavenetidou, Marina
    Mathematical approach for defining juvenile-mature wood transition zone in black locust and chestnut2011Ingår i: Wood and Fiber Science, ISSN 0735-6161, nr 3, 336-342 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article defines age of transition from juvenile to mature wood in two ring-porous species, black locust (Robinia pseudoacacia L.) and chestnut (Castanea sativa Mill.). A logistic function was proposed using fiber length and ring width data of three black locust trees, aged 35-37 yr, and five chestnut coppice trees, aged 25-27 yr, from Sithonia Peninsula, Chalkidiki, Greece. The approach proved to be practical and objective in delineating maturity zones, and it was based on rate of change of yearly fiber length. The juvenile wood zone spread to the sixth growth ring from the pith in both species, whereas the demarcation of juvenile and mature wood was at age 12 and 14 yr in chestnut and black locust, respectively. Transition zone width comprised rings 7-12 in chestnut and rings 7-14 in black locust.

  • 20.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Mechanical properties of sound and of deteriorated softwood at different length scales: Poromicromechanical modeling and experimental investigations2011Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Due to its natural origin and its inherent heterogeneities, mechanical properties of wood are highly anisotropic and show a broad variability, not only between different wood species, but also within a tree. Similar to other biological materials, the wood mi- crostructure is well organized and hierarchically structured from the annual rings visible to the naked eye down to the wood polymers cellulose, hemicellulose, and lignin at the nanometer-scale. This thesis aims at a deeper understanding of the role of different hi- erarchical levels and their corresponding physical and chemical characteristics in relation to mechanical properties of sound wood and of deteriorated wood. This is achieved by means of micromechanical modeling and experimental analyses.

    This thesis starts with the re-formulation of an existing micromechanical model for the elastic behavior and elastic limit states of wood in the framework of poromechanics. The mechanical role of cell wall water at different hierarchical levels is investigated by means of this model. In a broader sense, the developed model allows to investigate the transition of eigenstresses from the cell wall to the softwood level. Moreover, this poromicromechanical model forms the basis for subsequent consideration of a microscopic failure criterion for lignin for the derivation of softwood failure stresses. The suitability of the modeling approach is underlined by a satisfactory agreement of the model-predicted failure stresses with experimental results of biaxial strength tests on Norway spruce.

    As a result of partly considerably different microstructural characteristics, Common yew exhibits exceptional mechanical properties compared to other softwood species. The re- lationship between microstructure and stiffness properties of Common yew and Norway spruce is investigated by means of the poromicromechanical model and mechanical tests across various length scales. Moreover, this offers the opportunity of a broader model validation. The influence of differences in microfibril angle of the S2 cell wall layer and in mass density between yew and spruce is found to be more dominant than the influence of differences in the annual ring characteristics.

    The suitability of the poromicromechanical model to predict changes in mechanical prop- erties upon fungal decay is demonstrated. For this purpose, relationships between mi- crostructure and mechanical properties of deteriorated wood are experimentally explored. Changes in mechanical properties and in the microstructure, measured at pine wood samples after standard wood durability tests using one brown rot fungus (Gloeophyl- lum trabeum) and one white rot fungus (Trametes versicolor), are presented. Transverse stiffnesses are revealed to be more sensitive to degradation than longitudinal stiffness, particularly as a result of pronounced degradation of hemicelluloses. Moreover, ultrason- ically derived anisotropy ratios of elastic stiffnesses allow to identify certain degradation mechanisms of the two considered fungi. The experimental campaign is complemented by micromechanical modeling. For this purpose, the micromechanical model is extended to take into account degradation-specific microstructural characteristics. 

  • 21.
    Sehlstedt-Persson, Margot
    et al.
    Luleå University of Technology.
    Wamming, Thomas
    SPTrätek.
    Karlsson, Olov
    Luleå University of Technology.
    Ahmed, Sheikh Ali
    Luleå University of Technology.
    Modern torknings inverkan på impregnerbarhet i furusplint: Förstudie2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Under senare år rapporteras i Sverige för vissa impregneringsmedel en kraftig ökning av antalet underkända prov och då speciellt för kopparbaserade vattenlösliga medel. På några års sikt, när konsekvenserna av impregneringsmissar blir synliga hos slutanvändaren genom att rötskadat virke måste bytas ut, beräknas kostnaderna kunna uppgå till en halv miljard årligen. Orsakerna till inträngningsproblem diskuteras och en av många teorier är att virkestorkningen är en av huvudorsakerna. Målet med denna förstudie har varit att identifiera relevanta process- och materialvariabler som misstänks inverka på impregnerbarheten i furusplint. Resultat från impregneringsförsöken i denna förstudie visar att fuktkvotsnivån i bräder efter torkning är viktig för impregneringsresultatet. Bäst inträngning erhölls vid högre fuktkvotsnivåer än vad som vanligen används vid anläggningarna idag: i fuktkvotsintervallet 20-25 % var andelen missar lägst medan andelen missar ökade påtagligt vid sjunkande fuktkvot. En rekommendation är att inte övertorka virke som ska impregneras. Detta är vanligt speciellt vid torkning av tunna dimensioner i äldre brädkanaler.Resultat från denna förstudie sammanfattas enligt följande•Inverkan av fuktkvotsnivå vid impregnering är viktig. Bäst inträngning i bräder erhölls i fuktkvotsintervallet 20-25 %, dvs. vid högre fuktkvot än vad som vanligen görs medan missarna ökade påtagligt vid sjunkande fuktkvot. •Resultaten pekar på att splintvedsdensiteten tycks spela roll för impregnerbarheten: högre densitet tenderar att vara bättre ur impregneringssynpunkt. •Olika typer av impregneringsmissar noteras. Vissa typer har en tydlig koppling till vedanatomiska detaljer medan andra missar kopplas till process och yttre form.•Anrikning av näring mot splintvedsytor som sker vid forcerad torkning kan i vissa fall ha försvårat inträngning av träskyddsmedel.•Vedanatomiska studier visar att– axiella kådkanaler sannolikt spelar en viktig roll för inträngning av träskyddsmedel– parenkymcellers hartsinnehåll i splintved kan blockera inträngning via märgstrålar•Tomografering indikerar att hög splintvedsdensitet är gynnsamt för inträngning av träskyddsmedel. Detta överensstämmer med iakttagelsen att axiella hartskanaler är viktiga för inträngning av träskyddsmedel eftersom axiella hartskanaler främst finns i sommarved och hög densitet förknippas med hög sommarvedsandel. •Kemisk analys indikerar att lokal skillnad i extraktivämneshalt kan vara en av förklaringarna till impregneringsmiss i splintved. •I fortsatta studier är tomografering ett kraftfullt analysverktyg för att se inträngningsmissar i rått tillstånd.

  • 22.
    Dvinskikh, Sergey V.
    et al.
    Royal Institute of Technology KTH, Division of Physical Chemistry and Industrial NMR Centre, SE-100 44 STOCKHOLM, .
    Furó, István
    Royal Institute of Technology KTH, Division of Physical Chemistry and Industrial NMR Centre, SE-100 44 STOCKHOLM, .
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Söderström, Ove
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Moisture content profiles and uptake kinetics in wood cladding materials evaluated by a portable nuclear magnetic resonance spectrometer2011Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, Vol. 6, nr 3, 119-127 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have evaluated the capability of nuclear magnetic resonance (NMR) technology based on small portable magnets for in situ studies of the local moisture content in wood. Low field and low resolution 1H NMR with a unilateral permanent magnet was used to monitor and map the moisture content of wood cladding materials of various types in a spatially resolved manner. The results show that portable NMR equipment based on small open-access permanent magnets can be successfully used for non-invasive monitoring of the moisture content in various extended wood specimens. The moisture content was measured with a depth resolution of 0.2 mm and a maximum penetration depth of 3 mm. This makes the technique suitable for e.g. in situ local moisture content measurements beneath a coating layer in the claddings and it is also possible to relate the moisture level to specific properties of the wood material.

  • 23.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    On the Relevance of Lignin Failure for Softwood Strength: a Poromicromechanical Approach2011Ingår i: XI International Conference on Computational Plasticity - Fundamentals and Applications, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2011Konferensbidrag (Övrigt vetenskapligt)
  • 24.
    Adamopoulos, Stergios
    et al.
    Technological Edicational Institute of Larissa, Greece.
    Voulgaridis, Elias
    Aristotle University, Greece.
    Passialis, Costas
    Aristotle University, Greece.
    Beaver, Tim
    Composites & Textiles Pera, UK.
    Bouras, Takis
    ELKEDE Technology & Design Centre S.A., Greece.
    Properties of Microwave heat treated oak wood and impregnated with soybean oil2011Ingår i: Program & Book of Abstracts: Workshop, “Mechano-Chemical transformations of wood during Thermo-Hydro-Mechanical processing” / [ed] Parviz Navi, Andreas Roth, 2011, 145-145 s.Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The poster presents selected data on physical and mechanical properties, and gluing behaviour of microwave heat treated wood and impregnated with natural oils.

  • 25.
    Nilsson, Jonaz
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Johansson, Jimmy
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Kifetew, Girma
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Shape stability of modified engineering wood product (EWP) subjected to moisture variation2011Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, Vol. 6, nr 3, 132-139 s.Artikel i tidskrift (Refereegranskat)
  • 26.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Chavenetidou, Marina
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Span-to-depth ratio for shear free deformations in static bending of small wood specimens2011Ingår i: Wood research, ISSN 1336-4561, Vol. 56, nr 3, 429-434 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Disregarding shear effects is a principal defect in predicting the bending strengths of small clear specimens of timber according to standards. The present study proposes a method to determine spans of 2 x 2 cm wood specimens of black locust and chestnut for shear free deformations in static bending. It was found that for both ring-porous species, spans of at least 40 cm in a bending test would ensure a negligible influence of shear on modulus of elasticity.

  • 27. Bader, Thomas K.
    et al.
    Braovac, Susan
    Fackler, Karin
    Hofstetter, Karin
    Stiffness Properties of the Archaeological Oak Wood from the Oseberg Ship2011Ingår i: Cultural Heritage Preservation.EWCHP - 2011: Proceedings of the European Workshop on Cultural Heritage Preservation. Berlin, Germany, September 26 to 28, 2011, Fraunhofer IRB Verlag, 2011, 164-170 s.Konferensbidrag (Refereegranskat)
  • 28.
    Eliasson, Lars
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Ställ krav på virket: Rätt virke för produktion i framtidens trähusfabrik2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna avhandling behandlar den svenska trähusbranschens behov och möjligheter att erhålla trämaterial med egenskaper som uppfyller de krav som produktion och slutkund ställer. Ett gemensamt problem för den svenska trähusbranschen är de kvalitetsbrister hos det virke sombranschens företag köper för sin produktion, som kan resultera i merkostnader för branschen med 100 MSEK årligen.

    Trähusföretagen uttrycker en viss uppgivenhet över bemötandet från virkesleverantörerna. Virkesleverantörerna å sin sida menar att köparna av trämaterial inklusive företagen i trähusbranschen i ringa utsträckning genomför reklamationer. Avgörande för genomförda virkesaffärer är ofta priset – det blir affär med den som erbjuder lägst pris. Sammantaget innebär detta att det inte blir någon dialog mellan leverantör och köpare som utvecklar synsättet på trämaterialkvalitet.

    Avhandlingsarbetet har bland annat behandlat beredning av träråvaran till färdiga ämnen t.ex. studier vid tillverkning av kvistfria ämnen. Resultatet av arbetet visar på vikten av att genomföra utvärderingar av material och leverantörer. Resultatet visar vidare att kapkostnaden för färdiga träämnen inkl. spill är ca 1/3 av ämneskostnaden. Dock är kostnaden för trämaterialet låg i relation till totalkostnaden för det färdiga huset vilket innebär att ett högre pris för ett virke som fullt ut motsvarar kravspecifikationerna i liten utsträckning påverkar totalkostnaden för huset.

    Råd till trähusbranschen är att ställa krav på virkesråvaran, utvärdera material och leverantörer samt att trähusbranschen ska sikta mot att bli en modern tillverkningsindustri i likhet med de mest framgångsrika inom verkstadsindustrin.

  • 29.
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Ta betalt för virkeskvalitete!2011Ingår i: Skogsmästaren, Vol. -, nr 4, 23- s.Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 30.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Al - naser, Zakaria
    The Effect of Ethanol/Cyclohexane-Extract of the heart wood of some wood species in inhibition mycelium growth to Fusarium and Alternaria and compare with fungicides in laboratory.2011Ingår i: Research Journal of Aleppo University, Vol. 93, nr 2, 115-126 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This investigation carried out in 2010, to study the effect of ethanol / cyclohexan extract for heart wood of Biota orientalis, Pinus pinea and Abies cilicica, in inhibition mycelium growth to fungi Alternaria alternate and Fusarium solani and compared with fungicides (thiophanate-m , chlorothalonil and mancozeb)  on PDA in laboratory. The obtained results showed that thiophanate-m gave the superior inhibition for F. solani ,where gave 100% inhibition at concentration 60 ppm. While the fungicide chlorothalonil gave the lowest inhibition to F. solani , where EC50 (73 ppm). At contrast, the fungicide chlorothalonil gave the highest inhibition to A.alternate at used concentrates. Where cause 100% inhabition  at 100 ppm. Also the results showed that mancozeb gave moderate effect on both fungi, where EC50 37ppm an 58 ppm to F. solani and A. Alternate, respectively. On the other hand, the result showed that wood extract of study species gave significant inhibition to growth fungi compare with the control. the Ethanol/Cyclohexane-Extract of the heart wood of Biota orientales gave the superior effect inhibition to A. alternata ,where gave 100%  inhibition at 150 ppm. While the Ethanol/Cyclohexane-Extract of the heart wood of (Abies cilicica) gave the highest inhibition to F.solani , where the percentage inhibition at concentrate 125 ppm were 100%. In contrast,  the Ethanol/Cyclohexane-Extract of the heart wood of (Pinus pinea) gave moderate inhibition to A. Alternate, where EC50 (94 ppm). While gave the lowest  effect in F. solani. Therefore we recommended to use the ethanol/ cyclohexane extract of the heart wood of Biota and Abies as Environment friendly fungicides. 

     

  • 31.
    Jäger, Andreas
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    The relation between indentation modulus, microfibril angle, and elastic properties of wood cell walls2011Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 42, nr 6, 677-685 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanoindentation is a well known tool for identification of mechanical properties at the micrometer scale of materials. When applied to study wood cell walls the commonly used isotropic indentation theory is not applicable. In this study, anisotropic nanoindentation theory was employed for analyzing nanoindentation test results on wood cell walls. The influence of elastic stiffness components, microfibril angle, and cell wall composition on the indentation modulus was studied. The indentation modulus was found to depend on longitudinal, transverse, and shear modulus to a similar extent. A significant influence of the microfibril angle on the indentation modulus was observed and discussed with respect to experimental scatter and sample preparation. It is concluded, that application of anisotropic nanoindentation theory provides a tool for quantitative instead of qualitative investigation of wood cell walls, with the goal of identifying all elastic properties of the transversely isotropic cell wall from nanoindentation tests.

  • 32.
    Eliasson, Lars
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Sandberg, Dick
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Trähusföretag tappar fördel i slarvig tillverkning.2011Ingår i: Husbyggaren, ISSN 0018-7968, nr 7, 24-27 s.Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    BYGGMETODER Ska trä öka sin konkurrenskraft måste trähusföretag och virkesleverantörer bli bättre på att både ställa och uppfylla kravspecifikationer. Idag kan materialspill och felleveranser uppgå till närmare en femtedel av virkeskostnaden.

    Trähusbranschen står inför ett antal utmaningar. Avgörande är att kunna producera attraktiva bostäder till en kostnad som inte är högre än att människor har råd.

    Trähusföretagen utnyttjar inte fullt ut material och metoder som är anpassade för en effektiv produktion av hus i fabrik. I den kontexten får träets miljöfördelar en underordnad betydelse i konkurrensen med andra mindre miljömässigt uthålliga material.

  • 33.
    Sandberg, Dick
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Azoulay, Michel
    Baudin, Anders
    Blom, Åsa
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Carlsson, Bo
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Eliasson, Lars
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Johansson, Jimmy
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Kifetew, Girma
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Nilsson, Bengt
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Nilsson, Daniel
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Nilsson, Jonaz
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Nordvall, Hans-Olof
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för teknik, TEK.
    Utvändiga träfasader: Inverkan av materialval, konstruktion och ytbehandling på beständigheten hos fasader av gran och tall2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Den utvändiga fasaden ska ge byggnaden ett uttryck genom utformning och kulör. Fasaden ska också skydda de isolerande skikten i väggen från yttre påverkan. Dessa funktioner kan uppfyllas av i stort sett alla material. Om trä ska trä vara konkurrenskraftigt måste trämaterialet, fasadkonstruktionen och ytbehandlingssystemet väljas och samverka på ett sådant sätt att fasaden får en lång livslängd med litet och lågt underhåll. Därigenom blir träfasaden ekonomiskt och estetiskt attraktiv för brukaren i vid mening.

    Denna studie belyser kunskapsfronten för utomhusanvändning av träslagen tall (Pinus sylvestris L.) och gran (Picea abies L. Karst.) ovan mark. Specifikt studeras användning i fasader utifrån aspekterna materialval, fasadkonstruktion, ytbehandling samt återvinning.

    Marknaden efterfrågar träfasadsystem. De behov som marknadens aktörer, dvs. byggherrar, fastighetsförvaltare, arkitekter, konstruktörer, stomleverantörer, entreprenörer och representanter för småhusindustrin, framhäver kan sammanfattas i följande punkter:

    • Behov av specificerad livslängd och givna tidsintervall för underhåll av träfasader. (Ska vara i nivå med konkurrerande material)
    • Det är önskvärt att leverantören av ett fasadsystem ikläder sig ett långsiktigt ansvar för underhåll.
    • Flexibilitet, leverantören ska kunna byta ut eller renovera fasaden vid behov.
    • Byggkrav, träfasadmaterial måste kunna samverka med andra, speciellt brandklassade, material.
    • Fasadsystem skall vara utseendemässigt attraktivt.

    Den primära marknaden för nya fasadsystem bör vara flerbostadshus, men inte nödvändigtvis flerbostadshus av trä. Fokus ska ligga på fasadsystemets flexibilitet i arkitektoniskt uttryck och i relation till andra material och system. Nybyggnation är viktigt, men miljonprogrammet, renovering och tillbyggnad (ROT) samt energieffektivisering är också viktiga områden.

    Den svenska marknaden är liten (idag ca. 70 000 m3 trä för fasader), men bör inledningsvis ändå prioriteras och därefter de nordiska länderna, samt Schweiz, Österrike och Tyskland.

    I litteraturen beskrivs mer eller mindre välgrundade rekommendationer för att förlänga träfasaders livslängd och öka dess underhålls-intervall. Vissa av rekommendationerna är dock direkt motstridiga.

    När aspekterna materialval, fasadkonstruktion och ytbehandling studeras finns det många detaljer som har betydelse för träfasadens beständighet. Det är svårt att sära ut de mest väsentliga faktorerna, men utan att ta hänsyn till aspekter som kostnader, tillgång, eller andra av praktiskt karaktär viktiga faktorer kan följande nyckelfaktorer identifieras för en miljöriktig och beständig fasad av tall eller gran:

    Materialval

    • Hög andel kärnved, helst uteslutande kärnved
    • Virket ska ha stående årsringar
    • Hanteringen ska utföras så att virket inte får mekaniska skador, får mikrobiella angrepp, eller blir uppfuktat eller nedsmutsat, dvs. snabb och rätt hantering, samt god emballering.
    • Från marken – fasaden ska börja minst 30 cm ovan marken.
    • Ventilation – utforma fasadbeklädnaden så att fukt snabbt kan torka ut. Ventilera utrymmet bakom fasaden vilket är ett enkelt sätt för att möjliggöra detta.
    • Vattenavrinning – inga horisontella ytor.
    • Flexibilitet – ska gälla både konstruktion och arkitektoniskt utförande. Fasadsystem som kan ”hängas på” befintliga byggnader efterfrågas.
    • Förseglat ändträ – försegling av ändträytor för att förhindra fuktupptagning i träet är helt avgörande för trämaterialets livslängd. Spikning kan öppna nya ändträytor och bör därmed utföras omsorgsfullt och med eftertanke.
    • Rundade virkeskanter – ger bättre täckförmåga hos färgen och minskar risk för mekaniska skador på fasadbrädorna.
    • Val av ytbehandling – spelar en nyckelroll för fasadens prestanda. En träfasad ska levereras som en del av ett komplett underhållspaket.

    Hantering från skog till fasadKonstruktionYtbehandling

    För ytbehandling finns idag många tillämpningar där nanotekniken utnyttjas för att skapa mervärde hos en yta jämfört med vad dagens mer traditionella produkter kan erbjuda. Nanobaserade ytbehandlingsprodukter marknadsförs redan idag och där uppges de göra ytor smuts- och vattenavvisande, förhindra påväxt av alger, svamp och mossa, förbättra UV- och temperaturresistensen och kulörbeständigheten, förbättra rep- och nötningståligheten, samt ha antigraffiti egenskaper etc. De flesta produkterna är dock nya och för en del finns därför frågetecken vad gäller t.ex. långtidsprestanda och teknisk livslängd, underhållbarhet och därmed sammanhängande ekonomi sett ur ett livscykelperspektiv för den produkt eller system där ytbehandlingen utgör bara en del.

    En kostnadsanalys som genomförts i studien gör bedömningen att nya nanoteknikbaserade ytbehandlingssystem skulle kunna ge som mest en reduktion av underhållskostnaderna med 15 %. Antagandet är då att fasadrengöring behöver göras vart femte eller sjunde år då traditionella målningssystem används.

    Återvunnet trä från träfasader definieras enligt Svensk standard som trädbränsle och benämns generellt för returträ eller när materialet är i finfördelad form för returflis.

    Ett stort problem med att återvinna energin från returträ är att en del av materialet är behandlat på något sätt, t.ex. impregnerat med träskyddsmedel, ytbehandlat eller innehåller andra konstruktionsdelar av t.ex. plast eller metall. Returflis är ett utmärkt bränsle för energiåtervinning förutsatt att anläggningen har tillräcklig rökgasrening och att askan hanteras på ett korrekt sätt. Ett problem idag är vad som ska ske med förorenad askan då den klassas som farligt avfall och därmed inte kan återföras till skogen. Om halterna av tungmetaller inte är för höga kan askan användas som täck- och fyllmaterial annars måste askan gå till deponi.

    En bättre källsortering och översyn av regelverk skulle dessutom kunna leda till att det renare returträet skulle kunna eldas i konventionella biobränslepannor medan den förorenade andelen då skulle eldas separat.

     

  • 34.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Voulgaridis, Elias
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Wood recycling in Europe2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nowadays, waste wood is a valuable secondary raw material that can cover much of the wood-based panel industry's needs and a major source of renewable energy. The various categories of waste wood are described in European legislation and standards but in practice mostly followed industry practices relating to the purchase, classification and use of recovered wood. The European Panel Federation (EPF) proposes a three category classification system: untreated wood, non-hazardous treated wood, hazardous waste wood. The traditional practice of recycling in industry included mechanical handling of waste wood while new improved methods involve hydrothermal treatments. Of the total approximately 30 million cubic meters of recovered wood in Europe 38% is recycled, 34% is used for energy production and 28% ends up in landfills or composting. In the future recovered wood is expected to play an increasingly important role in the sustainability of wood-based panel industries as well as for the protection of the environment, and therefore new technologies are needed to fully explore this valuable resource.

  • 35.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Koch, Gerald
    Johann Heinrich von Thünen-Institut, Germany.
    Wood structure and topochemistry of Juniperus excelsa2011Ingår i: IAWA Journal, ISSN 0928-1541, Vol. 32, nr 1, 67-76 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood structure and topochemical distribution of lignin and phenolic extractives in Juniperus excelsa Bieb. were investigated using a mature specimen, aproximately 80 years of age, from the Rhodope mountains, Greece. The wood of J. excelsa was found to possess the same qualitative anatomical features as those reported for other Juniperus species of the Western Hemisphere. Quantitative anatomical characteristics recorded for mature wood (heartwood and sapwood) included earlywood and latewood tracheid length, double wall thickness of earlywood and latewood tracheids, lumen diameter of earlywood tracheids and ray height. Scanning UV microspectrophotometry revealed a pronounced lignification of J. excelsa tracheids with detected absorbance values of the secondary cell wall layers being much higher in comparison to all other softwoods studied using this technique. The cell corners and compound middle lamellae were characterised by relative high UV absorbance values as compared to the S2 layers. The phenolic compounds deposited in the axial and ray parenchyma cells possessed higher absorbance values than cell wall associated lignins and had a different spectral behaviour due to the presence of chromophoric groups. According to the obtained UV absorbance spectra, more condensed phenolic compounds were deposited in the heartwood than in the sapwood.

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