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  • 701.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Hofstetter, Karin
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Nanoindentation and Micromechanical Modeling to Explore the Mechanical Performance of Deteriorated Softwood2011Inngår i: COST Action FP0802 - Experimental and Computational Micro-Characterization Techniques in Wood Mechanics, Helsinki, Finland, 2011, s. 61-62Konferansepaper (Annet vitenskapelig)
  • 702.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    A combined view on composition, molecular structure, and micromechanics of fungal degraded softwood2015Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 4, s. 471-482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fungal decay alters the composition, microstructure, and mechanical properties of wood cell walls. To understand better the structure-function relationships during fungal decay, selected annual rings of fungal deteriorated Scots pine sapwood were analyzed in terms of their composition, microstructure, and micromechanical properties. The datasets were acquired separately for earlywood and latewood concerning the S2 cell wall layer and the cell corner middle lamella (CCML) and analyzed by means of principal component analysis and partial least squares regression analysis. Links between cell wall stiffness and hardness and the composition and microstructure could be established. Increased mechanical properties in the CCML, as obtained by nanoindentation, were correlated to the degradation of pectins. In the S2 layer, the altered data were related to the degradation of hemicelluloses and lignin modification during fungal decay.

  • 703.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bos, Clemence
    Vienna University of Technology, Austria ; Institute for applied materials, Germany.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Effect of Water on the Mechanical Properties of Wood Cell Walls: Results of a Nanoindentation Study2015Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper presents a nanoindentation study on five different wood species in which the elastic and creep properties of the S2 cell wall layer and the middle lamella were determined. Measurements were carried out at relative humidities (RH) ranging from 10 to 80% as well as underwater. Indentation moduli were found to decrease by about a third in the S2 layer and by about half in the middle lamella between RH of 10 and 80%. Hardness dropped by 50 to 60% in this humidity range in both the S2 layer and the middle lamella. Creep parameters were almost constant up to a relative humidity of 40%, but they increased considerably at higher RH. The most pronounced change of reduced moduli and creep properties occurred between 60 and 80% RH, which is consistent with the expected softening of hemicellulose and amorphous parts of cellulose in this humidity region. Immersion into water resulted in a further decrease of the reduced moduli to about 20 to 30% of their values at 10% RH and to only about 10 to 20% for the hardness. This can be explained by additional softening of the less ordered regions of cellulose.

  • 704. Wagner, Leopold
    et al.
    Bos, Clemence
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Moisture-Dependent Mechanical Properties of Softwood and Hardwood Cell walls: A Nanoindentation Study2014Inngår i: 16th International Conference on Experimental Mechanics (ICEM16), July 7-11, 2014, Cambridge, Cambridge, UK, 2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Wood is a hygroscopic material. Increasing moisture decreases the macroscopic mechanical properties of wood. Investigations of the mechanical behaviour of the solid wood substance at the cell wall scale may contribute to an enhanced insight into moisture-mechanics relationships. Wood cells walls are composed of several different layers, of which the S2 layer and the middle lamella (ML) are mechanically most important. Their mechanical properties can be assessed by nanoindentation. Wood of two hardwood species and three softwood species is investigated. Mechanical properties of the S2 layer as well as of the ML are determined at different relative humidity (RH), i.e. at different wood moisture contents (MC).

  • 705. Wagner, Leopold
    et al.
    Bos, Clemence
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Moisture-Dependent Mechanical Properties of Softwood and Hardwood Cell Walls: A Nanoindentation Study2014Inngår i: 31st Danubia-Adria Symposium on Advances in Experimental Mechanics, September 24-27, 2014, Kempten, 2014, s. 151-152Konferansepaper (Annet vitenskapelig)
  • 706. Wagner, Leopold
    et al.
    Fackler, Karin
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Ters, Thomas
    de Borst, Karin
    Fungal Degradation of Scots Pine (Pinus sylvestris L.) Wood: Micromechanical and Microstructural Characterization at the Cell Wall Level2012Inngår i: 7th International Plant Biomechanics Conference, August 20-24, 2012, Clermont-Ferrand, France, Clermont-Ferrand, France, 2012Konferansepaper (Annet vitenskapelig)
  • 707.
    Walford, Brian
    et al.
    Wood Quality and Solid Wood Products Forest Research.
    Ormarsson, Sigurdur
    Prediction of Twist in Poles that Contain Spiral Grain2003Inngår i: IAWPS2003 International Conference on Forest Products, 2003Konferansepaper (Fagfellevurdert)
  • 708.
    Wang, X. A.
    et al.
    Luleå University of Technology.
    Hagman, O.
    Luleå University of Technology.
    Sundqvist, B.
    SP Technical Research Institute of Sweden ; SP Sustainable Built Environment.
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Wan, H.
    Mississippi State University, USA.
    Niemz, P.
    ETH, Switzerland.
    Impact of cold temperatures on the shear strength of Norway spruce & scots pine joints with different glues2016Inngår i: WCTE 2016 - World Conference on Timber Engineering, Vienna University of Technology , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As wood construction increasingly uses engineered wood products worldwide, concerns arise about the integrity of the wood and adhesives used. Bondline strength is a crucial issue for engineered wood applications, especially in cold climates. In this study, the impact of cold temperatures on the shear strength of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) joints (150 mm x 20 mm x 10 mm) bonded with seven commercially available adhesives was studied. The cold temperatures investigated were: 20, -20, -30, -40, -50, and -60 °C. Generally, within the temperature test range, temperature changes significantly affected the shear strength of solid wood and wood joints for both species. As the temperature decreased, the shear strength decreased. PUR adhesive in most cases resulted in the strongest shear strength and MUF adhesive resulted in the weakest. But different adhesives responded differently with Norway spruce and Scots pine.

  • 709.
    Wang, Xiaodong Alice
    et al.
    Luleå University of Technology.
    Björnberg, Jonathan
    Luleå University of Technology.
    Hagman, Olle
    Luleå University of Technology.
    Ahmed, Sheikh Ali
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    Swiss Federal Institute of Technology in Zurich, Switzerland.
    Effect of Low Temperatures on the Block Shear Strength of Norway Spruce Glulam Joints2016Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 9638-9648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The block shear strength of Norway spruce (Picea abies (L.) Karst.) glulam joints was tested under low temperature. Glulam samples were glued with the three of the most common outdoor structural adhesives. The cold temperatures tested were 20, −20, −30, −40, -50 and −60 °C. Within the temperature test range, the block shear strength of the glulam joints was resistant to the effect of temperature. As the temperature decreased, the joints’ block shear strength did not show any significant change. In most cases, phenol-resorcinol-formaldehyde (PRF) adhesive yielded the strongest block shear strength, while melamine-formaldehyde (MF) adhesive yielded the weakest block shear strength. Melamine-urea-formaldehyde (MUF) adhesive yielded similar results to those of MF adhesives for all temperatures tested. The block shear strengths of the glulam joints with PRF, MUF and MF adhesives were not sensitive to temperature change. The results indicated that PRF, MUF and MF adhesives are stable for outdoor structural engineered wood construction in cold climate. The results also suggest that the SS-EN 14080 (2013) standard for the block shear method may not be the proper standard for testing differences in shear strength at different temperatures. The EN 302-1 (2011) standard could be more suitable for this purpose.

  • 710.
    Wang, Xiaodong (Alice)
    et al.
    Luleå Universoty of Technology.
    Hagman, Olle
    Luleå Universoty of Technology.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    ETH Zurich, Switzerland.
    Shear Strength of Scots Pine Wood and Glued Joints in a Cold Climate2016Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 1, s. 944-956Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impact of cold temperatures on the shear strength of Scots pine (Pinus sylvestris) joints glued with seven commercially available adhesives was studied in this work. The cold temperatures investigated were: 20, -20, -30, -40, and -50 degrees C. Generally, within the temperature test range, the shear strength of Scots pine solid wood and wood joints were more resistant to the effect of temperature than those of Norway spruce. As the temperature decreased, only some of the joints' shear strength significantly decreased. In most cases, PUR adhesive yielded the strongest shear strength and MUF adhesive yielded the weakest shear strength. MF adhesive responded to temperature changes in a similar manner to that of PUR and PVAc adhesives. The shear strengths of wood joints with PRF and EPI adhesives were more sensitive to temperature change. For dynamic tests of shear strength, the values for 12-h and 6-day tests under temperature cycles (-20 and 0 degrees C) were compared. The values for 6-day tests were lower than those for 12-h tests. Therefore, the duration of the samples subjected to the same temperature had a significant impact on shear strength. Our results indicate that PUR adhesive is the most stable; whereas the stability of MUF and PRF adhesives decreased significantly.

  • 711.
    Wang, Xiaodong
    et al.
    Luleå University of Technology.
    Hagman, Olle
    Luleå University of Technology.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Ormarsson, Sigurdur
    Technical University of Denmark, Denmark.
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    ETH Zurich.
    Impact of cold temperatures on the shear strength of Norway spruce joints glued with different adhesives2015Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, nr 2, s. 225-233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As wood construction increasingly uses engineered wood products worldwide, concerns arise about the integrity of the wood and adhesives used. Bondline strength is a crucial issue for engineered wood applications, especially in cold climates. In this study, Norway spruce (Picea abies) joints (150 mm × 20 mm × 10 mm) were bonded with seven commercially available adhesives: polyurethane (PUR), polyvinyl acetate (PVAc), emulsion-polymer-isocyanate (EPI), melamine-formaldehyde (MF), phenol-resorcinol-formaldehyde (PRF), melamine-urea-formaldehyde1 (MUF1), and melamine-urea-formaldehyde2 (MUF2). Each adhesive was tested at six temperatures: 20, −20, −30, −40, −50 and −60 °C. Generally, within the temperature test range, temperature changes significantly affected the shear strength of solid wood and wood joints. As the temperature decreased, the shear strength decreased. PUR adhesive in most cases resulted in the strongest shear strength and MUF adhesive resulted in the weakest. MF and PRF adhesives responded to temperature changes in a similar manner to that of the PUR adhesive. The shear strengths of wood joints with PVAc and EPI adhesives were more sensitive to temperature change. At low temperatures, the variability of shear strengths increased with all adhesives. Percent wood failures of joints bonded with different adhesives in most cases were not sensitive to temperature changes.

  • 712.
    Wang, Zhao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Recalcitrance of wood to biochemical conversion: feedstock properties, pretreatment, saccharification, and fermentability2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lignocellulose is an inexpensive and abundant renewable resource that can be used to produce advanced biofuels, green chemicals, and other bio-based products. Pretreatment and efficient enzymatic saccharification are essential features of bioconversion of lignocellulosic biomass. The aims of the research were to achieve a better understanding of the recalcitrance of woody biomass to bioconversion, to explore different pretreatment techniques that can be used to decrease the recalcitrance of the biomass and improve the digestibility of the cellulose, and to investigate by-products of acid pretreatment that cause enzymes and microorganisms to work less efficiently.

    The recalcitrance of wood from aspen, birch, and spruce was investigated before and after acid pretreatment. Before pretreatment, birch exhibited the highest recalcitrance, which was attributed to structural factors. After pretreatment, spruce showed the highest recalcitrance, which was attributed to chemical factors, such as high lignin content. Deacetylation of hybrid aspen in planta by a CE5 acetyl xylan esterase decreased the recalcitrance, and the glucose yield of enzymatic saccharification of non-pretreated wood increased with 27%.

    Pretreatment options based on ionic liquids and steam explosion were further explored. The effects of the anionic constituents of a series of imidazolium-based ionic liquids on pretreatment of aspen and spruce were investigated. [HSO4]− was efficient only for aspen, which was attributed to acid degradation of xylan. [MeCO2]− was efficient for both aspen and spruce, which was attributed to its capability to create a disordered cell wall structure rather than to removal of lignin and hemicellulose. A comparison was made between using sulfuric acid and sulfur dioxide for pretreatment of spruce. Although sulfur dioxide resulted in a pretreatment liquid that was more inhibitory to both enzymes and yeast, it was still superior to pretreatment with sulfuric acid, a phenomenon that was attributed to the particle size of the pretreated material.

    In a comparison of microbial inhibitors in pretreatment liquids from steam explosion of spruce, formaldehyde was found to be the most important inhibitor of yeast. Enzyme inhibition by catalytically non-productive adsorption to lignins and pseudo-lignin was investigated using quantitative proteomics. The results indicate that protein adsorption to pseudo-lignin can be as extensive as adsorption to real lignin. 

    Fulltekst tilgjengelig fra 2019-03-06 00:01
  • 713.
    Wernersson, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datoriserad bildanalys.
    Brun, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys.
    Luengo Hendriks, Cris L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datoriserad bildanalys.
    Segmentation of Wood Fibres in 3D CT Images Using Graph Cuts2009Inngår i: Image Analysis and Processing – ICIAP 2009, Berlin: Springer-Verlag , 2009, s. 92-102Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To completely segment all individual wood fibres in volume images of fibrous materials presents a challenging problem but is important in understanding the micro mechanical properties of composite materials. This paper presents a filter that identifies and closes pores in wood fibre walls, simplifying the shape of the fibres. After this filter, a novel segmentation method based on graph cuts identifies individual fibres. The methods are validated on a realistic synthetic fibre data set and then applied on μCT images of wood fibre composites.

  • 714.
    Wernersson, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datoriserad bildanalys.
    Luengo Hendriks, Cris L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys.
    Brun, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Centrum för bildanalys.
    Generating synthetic μCT images of wood fibre materials2009Inngår i: Proc. 6th International Symposium on Image and Signal Processing and Analysis: ISPA 2009, Piscataway, NJ: IEEE , 2009, s. 365-370Konferansepaper (Fagfellevurdert)
    Abstract [en]

    X-ray Computerized Tomography at micrometer resolution (μCT) is an important tool for understanding the properties of wood fibre materials such as paper, carton and wood fibre composites. While many image analysis methods have been developed for μCT images in wood science, the evaluation of these methods if often not thorough enough because of the lack of a dataset with ground truth. This paper describes the generation of synthetic μCT volumes of wood fibre materials. Fibres with a high degree of morphological variations are modeled and densely packed into a volume of the material. Using a simulation of the μCT image acquisition process, realistic synthetic images are obtained. This simulation uses noise characterized from a set of μCT images. The synthetic images have a known ground truth, and can therefore be used when evaluating image analysis methods.

  • 715. Wessels, C.B
    et al.
    Crafford, P.L
    du Toit, B
    Grahn, Thomas
    RISE, Innventia.
    Johansson, M
    Lundqvist, Sven-Olof
    RISE, Innventia.
    Säll, H
    Seifert, T
    Variation in physical and mechanical properties from three drought tolerant Eucalyptus species grown on the dry west coast of Southern Africa2016Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Southern Africa, and specifically its western parts is dominated by low rainfall areas, and it is expected that the rainfall in most of these parts will in future decrease further due to climate change. Woodlots of fast-growing, non-invasive tree species can provide the opportunity to produce wood and release the pressure on natural woodlands, while creating much needed income to inhabitants. Over the last two decades several trials of Eucalyptus species that could potentially withstand arid conditions were established on the South African west coast. The three most promising genotypes according to their volume growth were selected among 46 pure and hybrid species from two 20-year-old trials for further evaluation. These included 10 Eucalyptus grandis × Eucalyptus camaldulensis hybrid trees, 9 Eucalyptus gomphocephala trees, and 9 Eucalyptus cladocalyx trees for a total of 28 trees. The objective of the study reported here was to investigate the within-tree and between species variability of selected physical and processing properties determining the suitability of these three species for lumber production. The density, microfibril angle, spiral grain angle, MOE, MOR, radial and tangential shrinkage, twist, bow, splitting, and collapse were measured in a radial and longitudinal gradient. Valuable insights were gained which could provide decision support for planting, processing and further research on these species when grown in arid conditions. The E. grandis × camaldulensis hybrid was inferior in terms of most relevant properties to the other two species evaluated. The main shortcoming of both E. gomphocephala and E. cladocalyx was the high levels of twist in lumber.

  • 716. Wikete, Christoph
    et al.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Jäger, Andreas
    Hofstetter, Karin
    Eberhardsteiner, Josef
    Mechanical Properties and Microstructural Characteristics of Hardwood2010Inngår i: 27th Danubia-Adria Symposium on Advances in Experimental Mechanics : September 22nd - 25th, 2010, Wrocław University of Technology, Wrocław, Poland / [ed] Romuald Be̜dziński, Wroclaw, Poland: Wrocław University of Technology , 2010, s. 237-238Konferansepaper (Annet vitenskapelig)
  • 717.
    Wiklund, Martin
    et al.
    KTH.
    Sandberg, Dick
    KTH, .
    The Concept of Value Activation - Wood Properties at Different Annual Ring Orientation in Pine (Pinus Silvestris L).1998Inngår i: Timber and Wood Composites for the Next Century / [ed] Song-Yung Wang and Min-Chyuan Yeh, 1998Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An integrated R&D program called "Value Activation" has been carried out for the past eight years at the Royal Institute of Technology, Div. of Wood Technology and Processing (KTH-Trä). The concept of Value Activation is focused on the basic understanding of wood, and the fact that there are properties that are not fully exploited in conventional wood manufacturing systems to date. The strategy is to activate these inherent properties by a better understanding of the fundamental behaviour of wood, combined with new applied process technology and the development of the required manufacturing systems.

    The Value Activation program has so far shown that there are great possibilities of utilizing the properties of wood in a better way than our conventional wood production concept can achieve. New wood products with desirable properties can be developed. Most of these products are expected to give a greater added value to the wood. The R&D program will continue with the further development of improved products and also with the development of cost-efficient production systems for implementing the ideas from our R&D in profitable production units.

    Within the Value Activation program the following properties, which were judged to be the most important ones for future wood products were chosen:

    • Aesthetic and tactile factors
    • Controlled moisture movements
    • Accuracy in size and geometry
    • No checks and splits
    • Strength and hardness

    These properties are all strongly influenced by the annual ring orientation in the cross section of the sawn timber. This paper describes the influence of the annual ring orientation on these properties and how they can be improved by using a new sawing pattern.

  • 718.
    Wimmer, Rupert
    et al.
    Univ Bodenkultur Wien BOKU.
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Effects of Reaction Wood on the Performance of Wood and Wood-Based Products2014Inngår i: The Biology of Reaction Wood / [ed] Gardiner, B., Barnett, J., Saranpää, P., Gril, J., Springer, 2014, 1, s. 225-248Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Compression wood in softwoods and tension wood in hardwoods have properties, which adversely affect its usefulness for wood products. This chapter shows that reaction wood can be associated with many unsuitable wood properties. The results vary due to the fact that definitions about occurrence and severity of reaction wood are scarcely documented. A few properties seem to be even benefitting from the presence of reaction wood: the higher smoothness of compression wood surfaces, better shear strength of compression wood, higher toughness and impact resistance when tension wood is present, lower water uptake and swelling in fibreboards containing compression wood, and higher durability against fungi of compression wood. However, these are outweighed by disadvantages, which is the reason why reaction wood has a bad reputation in industry. The problem with reaction wood is that it is in most cases mixed with normal wood, which leads to non-uniform and more variable properties. This may lead to non-uniform swelling and shrinking, causing distortions, with additional problems of reduced strength and unfavourable surface properties. Wood-based materials such as particle boards or fibreboards are generally less prone to problems associated with reaction wood than solid wood products. With knowledge-based production methods the utilization of different wood types, including reaction wood, might be feasible.

  • 719.
    Winzell, Anders
    et al.
    KTH, Skolan för bioteknologi (BIO).
    Rajangam, Alex
    KTH, Skolan för bioteknologi (BIO).
    Arvestad, Lars
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Filling, Charlotta
    KTH, Skolan för bioteknologi (BIO).
    Divine, Christina
    KTH, Skolan för bioteknologi (BIO).
    Aspeborg, Henrik
    KTH, Skolan för bioteknologi (BIO).
    Master, Emma R.
    KTH, Skolan för bioteknologi (BIO).
    Teeri, Tuula T.
    KTH, Skolan för bioteknologi (BIO).
    Sequence Analysis and Recombinant Expression of Family 43 GlycosyltransferasesManuskript (preprint) (Annet vitenskapelig)
  • 720. Wojtasz-Mucha, J.
    et al.
    Hasani, Merima
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Chalmers University of Technology, Sweden.
    Theliander, Hans
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Chalmers University of Technology, Sweden.
    Hydrothermal pretreatment of wood by mild steam explosion and hot water extraction2017Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 241, s. 120-126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to compare the two most common hydrothermal pre-treatments for wood – mild steam explosion and hot water extraction – both with the prospect of enabling extraction of hemicelluloses and facilitating further processing. Although both involve autohydrolysis of the lignocellulosic tissue, they are performed under different conditions: the most prominent difference is the rapid, disintegrating, discharge employed in the steam explosion opening up the structure. In this comparative study, the emphasis was placed on local composition of the pre-treated wood chips (of industrially relevant size). The results show that short hot water extraction treatments lead to significant variations in the local composition within the wood chips, while steam explosion accomplishes a comparably more even removal of hemicelluloses due to the advective mass transport during the explosion step.

  • 721.
    Xiao, Zefang
    et al.
    Georg-August-University of Gottingen, Germany.
    Xie, Yanjun
    Northeast Forestry University, Kina.
    Adamopoulos, Stergios
    Georg-August-University of Gottingen, Germany.
    Mai, Carsten
    Georg-August-University of Gottingen, Germany.
    Effects of chemical modification with glutaraldehyde on the weathering performance of Scots pine sapwood2012Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 46, nr 4, s. 749-767Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Scots pine sapwood was treated with glutaraldehyde (GA) in aqueous solution using magnesium chloride as a catalyst in order to evaluate the durability towards weathering. Infrared spectroscopy suggested that GA treatment increased the photo-stability of lignin during artificial weathering of micro-veneers in a QUV over 168 h; photo-protection increased with increasing GA concentration. In comparison with the unmodified controls, GA-modified pine micro-veneer strips exhibited a lower tensile strength loss measured in a zero-span mode in the course of weathering. During 18 months of outdoor exposure, GA-modified pine wood boards exhibited a lower moisture content and water uptake than the unmodified ones. GA treatment also clearly restricted the penetration of blue stain fungi into deeper layers of wood. On the macroscopic scale, the surface of the GA-modified boards was significantly smoother due to less erosion, cracking and minor peeling of tracheids. Scanning electron microscopy further revealed that individual tracheids were detached from the cell compound and then washed away from the unmodified wood surface, whereas tracheids on surfaces of GA-modified wood remained in the tissue compound but displayed many axial and transversal cracks.

  • 722. Yin, Y.
    et al.
    Berglund, L.
    Salmen, L.
    RISE, Innventia.
    Effect of steam treatment on the properties of wood cell walls2011Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, nr 1, s. 194-202Artikkel i tidsskrift (Fagfellevurdert)
  • 723. Yin, Yafang
    et al.
    Berglund, Lars
    Salmén, Lennart
    RISE., Innventia.
    Effect of compressive treatment by steaming on the properties of wood cell walls2011Konferansepaper (Fagfellevurdert)
  • 724.
    Zajaczkowska, Ursula
    et al.
    Warsaw University of Life Sciences.
    Lundqvist, Sven-Olof
    RISE., Innventia.
    Bujalski, Mateusz
    Warsaw University of Life Sciences.
    Reaction wood formation during stem gravitropic response of young Picea Abies (L.) Karst. trees2016Bok (Fagfellevurdert)
  • 725. Zander, A
    et al.
    Hidemark, O
    Thörnqvist, Thomas
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design.
    Trä som byggnadsmaterial: -tekniska anvisningar2007Rapport (Annet vitenskapelig)
  • 726.
    Zheng, Chao
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Cellulose-fiber-based thermal insulation materials with fungal resistance, improved water resistance and reaction-to-fire properties2017Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Thermal insulation materials made from natural fibrous materials, such as cellulose fibers, have advantages over others from a sustainability point of view. However, cellulosic materials are generally prone to mold and absorb moisture, and these have negative effects on the insulation properties, the durability of insulation materials, and interior air quality. In this thesis, cellulose-fiber-based insulation foams were prepared from bleached chemithermomechanical softwood pulp, and these foams showed promising thermal insulation properties and fungal resistance. Hydrophobic extractives were isolated from birch (Betula verrucosa) outer bark and used to improve the water resistance of the foams, which were impregnated in solutions of extractives and then dried. The modified foams showed greater water resistance, and the modification had no negative effects on the thermal insulation, fungal resistance, and compressive strength of the foams.

    Another potential problem with low density cellulosic thermal insulation materials is their poor reaction-to-fire properties. Cellulose-fiber-based insulation foams were prepared from formulations containing bleached chemithermomechanical softwood pulp and commercial fire retardants to improve the reaction of the foams to fire. Single-flame source test results showed that the foams containing 20% expandable graphite (20% EG) or 25% synergetic (25% SY) fire retardant had significantly improved reaction-to-fire properties and passed class E, which reflected that they can resist a small flame attack without substantial flame spreading for a short period according to EN 13501-1. Compared with the reference without any fire retardant, the peak heat release rate (Peak-HRR) of the 20% EG and 25% SY decreased by 62% and 39% respectively when the samples were subjected to a radiance heat flow of 25 kW m-2 in a Cone Calorimeter.

    The thesis demonstrates that it is possible to produce cellulose-fiber-based insulation materials with improved properties in terms of fungal, improved water resistance and reaction-to-fire properties.

  • 727.
    Zheng, Chao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Li, Dongfang
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Cellulose-fiber-based insulation materials with improved reaction-to-fire propertiesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The poor reaction-to-fire properties of cellulosic thermal insulation need to be improved to meet the safety regulations for building materials. In this study, cellulose-fiber-based insulation foams were prepared from formulations containing mechanical pulp and commercial fire retardants. Results of single-flame source tests showed that foams developed from the formulations with 20% expandable graphite (EG) or 25% synergetic (SY) fire retardants had substantially improved reaction-to-fire properties, and passed fire class E according to EN 13501-1. The results indicated that the foams could resist a small flame attack without serious flame spreading over a short period of time. Compared with the reference foam that contained no fire retardant, the peak heat release rate (Peak-HRR) of the 20% EG and 25% SY foams decreased by 62% and 39% respectively when the samples were subjected to a radiance heat flow of 25 kW m-2 in a Cone Calorimeter, which suggested enhanced reaction-to-fire properties of these foams.

  • 728.
    Zheng, Chao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Li, Dongfang
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Cellulose-fiber-based insulation materials with improved reaction-to-fire properties2017Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 3, s. 466-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The poor reaction-to-fire properties of cellulosic thermal insulation need to be improved to meet the safety regulations for building materials. In this study, cellulose-fiber-based insulation foams were prepared from formulations containing mechanical pulp and commercial fire retardants. Results of single-flame source tests showed that foams developed from the formulations with 20% expandable graphite (EG) or 25% synergetic (SY) fire retardants had substantially improved reaction-to-fire properties, and passed fire class E according to EN 13501-1. The results indicated that the foams could resist a small flame attack without serious flame spreading over a short period of time. Compared with the reference foam that contained no fire retardant, the peak heat release rate of the 20% EG and 25% SY foams decreased by 62% and 39% respectively when the samples were subjected to a radiance heat flux of 25 kW m-2 in a cone calorimeter, which suggested enhanced reaction-to-fire properties of these foams.

  • 729.
    Zheng, Chao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Li, Dongfang
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Ottenhall, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Cellulose fiber based fungal and water resistant insulation materials2017Inngår i: International Journal of the Biology, Chemistry, Physics, and Technology of Wood, E-ISSN 1437-434XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of thermal insulation materials from sustainable, natural fibrous materials is desirable.In the present study, cellulose fiber based insulation foams made of bleached chemi thermo mechanical pulp(CTMP) have been investigated. To improve water resistance, the foams were impregnated with hydrophobic extractives from the outer bark of birch (Betula verrucosa)and dried. The surface morphology of the foams and the distribution of the deposited particles from the extractives were observed by scanning electron microscopy (SEM).The modified foams showed improved water resistance, as they did not disintegrate after immersion in water for7 days, whereas the unmodified foam did. Compared to the unmodified foam, the modified foams absorbed 50%less moisture within 24 h. The modification had no negative effects on the thermal insulation properties, fungal resistance or compressive strength of the foams. The proposed approach is simple and can be easily integrated into plants working based on the biorefinery concept.

  • 730. Ziaei Tabari, Hassan
    et al.
    Nourbakhsh, Amir
    Hosseinpourpia, Reza
    Danesh, Mohammad Amin
    Evaluation of mechanical and morphological behavior of polypropylene/wood fiber nanocomposite prepared by melts compounding2010Inngår i: International Conference on Nanotechnology and Biosensors, 28th to 30th December 2010, Hong Kong, Singapore, 2010, Vol. 2, s. 20-23Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Weak flexural properties of wood plastic composites(WPCs) limit their structural application. Recentlyinvestigation of nano particles looks promising to enhancebending properties of WPCs. In this study, the authors haveinvestigated the effect of different concentrations of nanoclay(modified montmorillonite) and coupling agent on themechanical and micro-structural properties of polypropylene/wood-fiber composites. We Bath internal mixer in certainprocessing conditions used for making the samples and then allsamples molded using injection molding for making samplesfor performing mechanical measurements. Samples preparedin four different concentration of nanoclay 0, 1, 3 and 5 wt%(total weight) and two different concentrations of maleicanhydride grafting (MAPP) 5 and 10 wt%. Mechanical resultsindicate that both flexural and impact strength of thecomposites increasing in sample containing 3% nano clay. Inother trend, Scanning Electron Microscope (SEM) imagesshow better interaction of wood fibers and polymer matrixwhen the authors added 5 wt% MAPP as coupling agent.

  • 731.
    Östman, Birgit
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Europeisk brandklassning av CLT och LVL2017Inngår i: Bygg & teknik, ISSN 0281-658X, Vol. 109, nr 6, s. 55-57Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [sv]

    Den europeiska brandklassningen av träbaserade produkter har nyligen utvidgats till att gälla även de två relativt nya träprodukterna CLT och LVL. Den täcker därmed praktiskt taget alla byggtillämpningar med träbaserade produkter. Brandklasserna har fastlagts genom ett system för förenklad europeisk brandklassificering för produkter som har ”känt och stabilt beteende vid brand”. Träprodukter är ett utmärkt exempel på sådana produkter. Brandklasserna avser både det europeiska systemet med så kallade Euroklasser A1-F och klasser för brandskyddande förmåga, så kallade K-klasser, se faktaruta.

  • 732.
    Östman, Birgit
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Fire safety in modern wooden houses: mapping of fire incidents in Sweden2017Inngår i: International fire protection, ISSN 1468-3873, nr 71, s. 46-48Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Multi-storey timber frame houses have been built in Sweden since 1994, when performance-based building regulations were introduced. The construction technology is now well established and steadily growing. Life safety protection is clearly defined in the building regulations. Now, property protection is being discussed from new perspectives.

    As a first step in better understanding, fire incidents have been mapped. The survey shows that modern apartment buildings with wooden frames have a lower rate of fire incidents than the entire stock of apartment buildings.

  • 733.
    Öyaas, K.
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Johnsen, I.A.
    Hoff, B.H.
    Opedal, Mihaela Tanase
    Toven, K.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Gulbrandsen, T.Aa.
    Hot water extraction of hemicellulose from softwood and sugarcane bagasse using microwave heating technology2012Konferansepaper (Fagfellevurdert)
12131415 701 - 733 of 733
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