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  • 1.
    Björngrim, N.
    et al.
    Luleå University of Technology, Sweden.
    Fjellström, P-A
    RISE - Research Institutes of Sweden, Built Environment, Building Technology.
    Hagman, O.
    Luleå University of Technology, Sweden.
    Resistance measurements to find high moisture content inclusions adapted for large timber bridge cross-sections2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 2, p. 3570-3582Article in journal (Refereed)
    Abstract [en]

    One challenge of monitoring and inspecting timber bridges is the difficulty of measuring the moisture content anywhere other than close to the surface. Damage or design mistakes leading to water penetration might not be detected in time, leading to costly repairs. By placing electrodes between the glulam beams, the moisture content through the bridge deck can be measured. Due to the logarithmic decrease of the resistance in wood as a function of electrode length, the model must be calibrated for measurement depth. Two models were created: one for electrode lengths of 50 mm and one for electrode lengths up to 1355 mm. The model for short electrodes differed by no more than 1 percentage points compared with the oven dry specimens. The model for long electrodes differed up to 2 percentage points for lengths up to 905 mm, and over that it could differ up to 4 percentage points.

  • 2.
    Blomqvist, Lars
    et al.
    RISE - Research Institutes of Sweden, Built Environment, Building Technology. Linnaeus University, Sweden.
    Berg, Sven
    Luleå University of Technology, Sweden.
    Sandberg, Dick
    Luleå University of Technology, Sweden; Czech University of Life Sciences Prague, Czech.
    Distortion in Laminated Veneer Products Exposed to Relative-Humidity Variations Experimental Studies and Finite-Element Modelling2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 2, p. 3768-79Article in journal (Refereed)
    Abstract [en]

    A shortcoming of the laminated bending process is that the product may become distorted after moulding. This study focused on the influence of fibre orientation deviation for individual veneers on the distortion of a moulded shell. The distortion of 90 cross-laminated shells of the same geometrical shape, consisting of seven peeled birch veneers, were studied under relative humidity variation. All the veneers were straight-grained in the longitudinal-tangential plane, but to simulate a deviation in fibre orientation, some of the individual veneers were oriented at an angle of 7 degrees relative to the main orientation of the other veneers in the laminate. A finite element model (FEM) was applied to study the possibility of predicting the results of a practical experiment. The study confirms the well-known fact that deviation in fibre orientation influences shape stability. The results also show how the placement of the abnormal veneer influences the degree of distortion. From this basic knowledge, some improvements in the industrial production were suggested. However, the FE model significantly underestimated the results, according to the empirical experiment, and it did not show full coherence. The survey shows the complexity of modelling the behaviour of laminated veneer products under changing climate conditions and that there is a great need to improve the material and process data to achieve accurate simulations. Examples of such parameters that may lead to distortion are density, annual ring orientation in the cross section of the veneer, the orientation of the loose and tight sides of the veneer, and parameters related to the design of the moulding tool.

  • 3. Brännström, Mattias
    et al.
    Oja, Johan
    SP- Sveriges Tekniska Forskningsinstitut, Trätek.
    Predicting the strength of sawn wood by tracheid laser scattering2008In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 3, no 2, p. 437-451Article in journal (Refereed)
  • 4.
    Brännvall, Elisabet
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    The limits of delignification in kraft cooking2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 2081-2107Article in journal (Refereed)
    Abstract [en]

    The perspective of the article is to explore kraft cooking at the limits of delignification, i.e. what degree of delignification is needed to obtain fibre liberation and what is the maximum degree of delignification possible in the kraft pulping stage. The reasons for the quite narrow boundaries for sufficient and maximum delignification are explained, and the differences between the behaviour of hardwood and softwood kraft pulping are clarified.

  • 5.
    Buck, Dietrich
    et al.
    Luleå University of Technology, Sweden.
    Wang, Xiaodong
    Luleå University of Technology, Sweden.
    Hagman, Olle
    Luleå University of Technology, Sweden.
    Gustafsson, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad, Träbyggande och boende.
    Bending Properties of Cross Laminated Timber (CLT) with a 45° Alternating Layer Configuration2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 2, p. 4633-4644Article in journal (Refereed)
    Abstract [en]

    Bending tests were conducted with cross laminated timber (CLT) panels made using an alternating layer arrangement. Boards of Norway spruce were used to manufacture five-layer panels on an industrial CLT production line. In total, 20 samples were tested, consisting of two CLT configurations with 10 samples of each type: transverse layers at 45° and the conventional 90° arrangement. Sample dimensions were 95 mm × 590 mm × 2000 mm. The CLT panels were tested by four point bending in the main load-carrying direction in a flatwise panel layup. The results indicated that bending strength increased by 35% for elements assembled with 45° layers in comparison with 90° layers. Improved mechanical load bearing panel properties could lead to a larger span length with less material.

  • 6.
    Buck, Dietrich
    et al.
    Luleå University of Technology, Sweden.
    Wang, Xiaodong
    Luleå University of Technology, Sweden.
    Hagman, Olle
    Lund University, Sweden.
    Gustafsson, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad.
    Comparison of different assembling techniques regarding cost, durability, and ecology - A survey of multi-layer wooden panel assembly load-bearing construction elements2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 4, p. 8378-8396Article in journal (Refereed)
    Abstract [en]

    Wood is a pure, sustainable, renewable material. The increasing use of wood for construction can improve its sustainability. There are various techniques to assemble multi-layer wooden panels into prefabricated, load-bearing construction elements. However, comparative market and economy studies are still scarce. In this study, the following assembling techniques were compared: laminating, nailing, stapling, screwing, stress laminating, doweling, dovetailing, and wood welding. The production costs, durability, and ecological considerations were presented. This study was based on reviews of published works and information gathered from 27 leading wood product manufacturing companies in six European countries. The study shows that the various techniques of assembling multi-layer wooden construction panel elements are very different. Cross laminated timber (CLT) exhibited the best results in terms of cost and durability. With regard to ecological concerns, dovetailing is the best. Taking into account both durability and ecological considerations, wooden screw-doweling is the best. These alternatives give manufacturers some freedom of choice regarding the visibility of surfaces and the efficient use of lower-quality timber. CLT is the most cost-effective, is not patented, and is a well-established option on the market today.

  • 7.
    Bäckström, Marie
    et al.
    RISE, Innventia.
    Hammar, Lars-Åke
    RISE, Innventia.
    The influence of the counter-ions to the charged groups on the refinability of never-dried bleached pulps2010In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 5, no 4, p. 2751-2764Article in journal (Refereed)
    Abstract [en]

    Refining of bleached hardwood pulps and bleached softwood pulps having different counter-ions to the charged groups within the fibres was studied. The results show that an energy reduction of 50% for the hardwood pulps and 20% for the softwood pulp can be achieved if 1he fibres are converted into the Na +-form prior to refining. The results also show that the amount of charged groups in the fibres is important for the refinability, which explains why the refining efficiency is much lower for bleached softwood fibres, which have a much smaller amount of charged groups than the bleached hardwood pulp.

  • 8. Dammström, S.
    et al.
    Salmen, Lennart
    RISE, STFI-Packforsk.
    Gatenholm, P.
    On the interactions between cellulose and xylan, a biomimetic simulation of the hardwood cell wall2009In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 4, no 1, p. 3-14Article in journal (Refereed)
    Abstract [en]

    The plant cell wall exhibits a hierarchical structure, in which the organization of the constituents on different levels strongly affects the mechanical properties and the performance of the material. In this work, the interactions between cellulose and xylan in a model system consisting of a bacterial cellulose/glucuronoxylan (extracted from aspen, Populus tremula) have been studied and compared to that of a delignified aspen fiber material. The properties of the materials were analyzed using Dynamical Mechanical Analysis (DMA) with moisture scans together with dynamic Infra Red -spectroscopy at dry and humid conditions. The results showed that strong interactions existed between the cellulose and the xylan in the aspen holocellulose. The same kinds of interactions were seen in a water-extracted bacterial cellulose/xylan composite, while unextracted material showed the presence of xylan not interacting with the cellulose. Based on these findings for the model system, it was suggested that there is in hardwood one fraction of xylan that is strongly associated with the cellulose, taking a similar role as glucomannan in softwood.

  • 9.
    Elustondo, Diego Miguel
    et al.
    Luleå University of Technology, Sweden.
    Myronycheva, Olena
    Luleå University of Technology, Sweden.
    Sundqvist, Bror
    RISE - Research Institutes of Sweden, Bioeconomy.
    Karlsson, Olov
    Luleå University of Technology, Sweden.
    Localized wood surface modification, Part I: Method characterization2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 283-295Article in journal (Refereed)
    Abstract [en]

    This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H & C) and compression-and-expansion (C & E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H & C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C. © 2017 North Carolina State University.

  • 10. Fredriksson, Magnus
    et al.
    Johansson, Erik
    Förädling och processer (TRf).
    Berglund, Anders
    Rotating Pinus sylvestris sawlogs by projecting knots from X-ray computed tomography images onto a plane2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 1, p. 816-827Article in journal (Refereed)
  • 11. Janga, K.K.
    et al.
    Öyaas, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hertzberg, T.
    Moe, S.T.
    Application of a pseudo-kinetic generalized severity model to the concentrated sulfuric acid hydrolysis of pinewood and aspenwood2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, p. 2728-2741Article in journal (Refereed)
  • 12. Kabir, M.M.
    et al.
    Castillo, Maria del Pilar 
    RISE, SP – Sveriges Tekniska Forskningsinstitut, JTI Institutet för Jordbruks- och Miljöteknik.
    Taherzadeh, M.J.
    Horvath, I.S.
    Effect of the N-methylmorpholine-N-oxide (NMMO) pretreatment on anaerobic digestion of forest residues2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 4, p. 5409-5423Article in journal (Refereed)
    Abstract [en]

    Pretreatment of forest residues using N-methylmorpholine-N-oxide (NMMO or NMO) prior to anaerobic digestion was investigated, where the effects of particle size, NMMO concentration, and pretreatment time were the primary focus. The pretreatments were carried out on forest residues; with different particle sizes of 2, 4 and 8 mm, at 120 °C for 3, 7, and 15 h in two different modes of NMMO-treatment: dissolution by 85% NMMO and swelling without dissolution using 75% NMMO solution in water. The pretreatment process led to minor changes in the composition of the forest residues. The best improvement in methane yield of the forest residues was achieved by pretreatment using 85% NMMO for 15 h at 120 °C. This treatment resulted in 0.17 Nm3/kg VS methane yield, which corresponds to 83% of the expected theoretical yield of carbohydrates present in the material. Additionally, the accumulated methane yield and the rate of the methane production were highly affected by the amounts of remaining NMMO when it was not well separated during the washing and filtration steps after the treatment. The presence of concentrations even as low as 0.008% NMMO resulted in a decrease in the final methane yield by 45%, while the presence of 1% of this solvent in the digester completely terminated the anaerobic digestion process.

  • 13.
    Knapic, Sofia
    et al.
    Universidade de Lisboa, Portugal.
    Grahn, Thomas
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Lundqvist, Sven-Olof
    RISE - Research Institutes of Sweden, Bioeconomy.
    Pereira, Helena
    Universidade de Lisboa, Portugal.
    Juvenile wood characterization of Eucalyptus botryoides and E. maculata by using SilviScan2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 2, p. 2342-2355Article in journal (Refereed)
    Abstract [en]

    The wood properties of 6-year-old Eucalyptus botryoides and Eucalyptus maculata point towards a possible aptitude for solid-wood end uses. Samples from E. botryoides and E. maculata were characterized regarding within-tree variation in wood density, radial and tangential fibre width, fibre wall thickness, fibre coarseness, microfibril angle, and stiffness based on SilviScan measurements taken radially from the pith outwards at varying stem height levels. The mean values of the studied wood properties for E. botryoides and E. maculata were, respectively: density 507 kg m-3 and 695 kg m-3, radial fibre width 17.4 Όm and 17.2 Όm, tangential fibre width 16.7 Όm and 16.9 Όm, fibre wall thickness 1.8 Όm and 2.5 Όm, fibre coarseness 161.2 Όgm-1 and 212.9 Όgm-1, microfibril angle 15.5° and 14.7°, and stiffness 9.6 GPa and 12.1 GPa. The variation in wood stiffness was explained to a large extent by microfibril angle and wood density variations. The results of the scans, along with the wood variability, indicated that both species should be considered for solid wood products or pulp production.

  • 14.
    Kumar, Vinay
    et al.
    Åbo Akademi University, Finland.
    Ottesen, Vegar
    NTNU, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Gregersen, Öyvind Weiby
    NTNU, Norway.
    Toivakka, Martti
    Åba Akademi University, Finland.
    Coatability of cellulose nanofibril suspensions: Role of rheology and water retention2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 7656-7679Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibril (CNF) suspensions are not easily coatable because of their excessively high viscosity and yield stress, even at low solids concentrations. In addition, CNF suspensions vary widely in their properties depending on the production process used, which can affect their processability. This work reports roll-to-roll coating of three different types of CNF suspensions with a slot-die, and the influence of rheology and water retention on coatability is addressed. The impact of CMC addition on the high and low shear rate rheology, water retention, coatability, and final coating quality of these suspensions is reported. All three CNF suspensions were coated successfully using the slot-die coating process. CMC addition further improved the coatability by positively influencing both the low and high shear rate viscosity and water retention of the CNF suspensions. All CNF coatings significantly improved the air, heptane vapor, grease and oil barrier, while reducing the water vapor transmission rate to some extent.

  • 15. Persson, J.
    et al.
    Dahlman, O.
    RISE, Innventia.
    Albertsson, A.-C.
    Birch xylan grafted with pla branches of predictable length2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, no 3, p. 3640-3655Article in journal (Refereed)
  • 16. Rodionova, G.
    et al.
    Roudot, S.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Männle, F.
    Gregersen, Ø.
    The formation and characterisation of sustainable layered films incorporating microfibrillated cellulose (MFC)2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, p. 3690-3700Article in journal (Refereed)
  • 17. Rusu, M.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Øjvind
    Yamakawa, A.
    Liukkonen, S.
    Relation between fibre flexibility and cross-sectional properties2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, p. 641-655Article in journal (Refereed)
  • 18.
    Salmen, L.
    et al.
    RISE, Innventia.
    Olsson, A.-M.
    RISE, Innventia.
    Stevanic, J.S.
    RISE, Innventia.
    Simonovic, J.
    Radotic, K.
    Structural organisation of the wood polymers in the wood fibre structure2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, no 1, p. 521-532Article in journal (Refereed)
  • 19.
    Salmen, Lennart
    et al.
    RISE, Innventia.
    Bergnor, Elisabeth
    RISE, Innventia.
    Olsson, Anne-Mari
    RISE, Innventia.
    Åkerström, Mårten
    RISE, Innventia.
    Uhlin, Anders
    RISE, Innventia.
    Extrusion of Softwood Kraft Lignins as Precursors for Carbon Fibres2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 4, article id 7544Article in journal (Refereed)
    Abstract [en]

    There is much interest in using less expensive raw materials as precursors for carbon fibre manufacture to increase the utilisation of strong, light-weight composite materials in the transportation sector. One such potential raw material is lignin. Most studies exploring melt spinning of lignin have used lignins from organosolv or hardwood kraft delignification processes. There has been little success reported in utilisation of the more commercially available softwood kraft lignins. In this study, lignins from different softwood kraft cooking processes were investigated with respect to their melt spinning performance and conversion to carbon fibres. The isolated lignins differed mainly in molecular weight, glass transition temperature, and softening temperature. All of the lignins produced from the laboratory cooks could be extruded without any plasticizer addition. However, the lignins contained volatiles that resulted in bubbles being formed along the length of the fibres. After vacuum drying, at elevated temperatures to remove volatiles, only the lignin originating from conventional kraft cooking was able to be melt extruded without plasticiser addition; this lignin had the lowest molecular weight amongst the samples. The stabilisation and carbonisation of these fibres gave carbon fibres with strengths comparable to those produced from lignins of other origins.

  • 20.
    Segerholm, Kristoffer
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP Trä.
    Ibach, R.E.
    Forest Products Laboratory, USA.
    Wålinder, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP Trä.
    Moisture sorption, biological durability, and mechanical performance of WPC containing modified wood and polylactates2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 4, p. 4575-4585Article in journal (Refereed)
    Abstract [en]

    Biological durability is an important feature for wood-plastic composites (WPC) intended for outdoor applications. One route to achieving WPC products with increased biological durabilityis to use wood preservative agents in the formulation of the WPC. Another option could be to use a chemically modified wood component that already exhibits increased resistance to biologicaldegradation. There is also a need to use biobased thermoplastics made from renewable resources, which would decrease the dependency on petrochemically-produced thermoplastics in the future. The objective of this study was to examine moisture sorption properties, biological durability, and mechanical performance of injection-molded WPC samples based on acetylated or thermally modified wood components and a polylactate matrix. The biological durability was evaluated in a terrestrial microcosm (TMC) test according to ENV 807, followed by mechanical evaluation in a center point bending test. The moisture sorption properties were investigated via both water soaking and exposure in a high-humidity climate. Low or negligible mass losses were observed in the TMC test for all WPC samples. However, the mechanical evaluation after exposure in the TMC test showed 35-40% losses in both strength and stiffness for the WPC containing an unmodified wood component.

  • 21.
    Segerholm, Kristoffer
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP Trä.
    Ibach, R.E.
    Forest Products Laboratory, USA.
    Wålinder, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP Trä.
    Moisture sorption in artificially aged wood-plastic composites2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 1, p. 1283-1293Article in journal (Refereed)
    Abstract [en]

    Moisture sorption in wood-plastic composites (WPCs) affects their durability and dimensional stability. In certain outdoor exposures, the moisture properties of WPCs are altered due to e.g. cracks induced by swelling and shrinkage of the components, as well as UV degradation or biological attack. The aim of this work was to study the effect of different artificial ageing routes on the moisture sorption properties of WPCs. Extruded WPCs were prepared with either unmodified or acetylated wood and recycled high-density polyethylene (HDPE). The WPC samples were artificially aged involving water soaking, artificial weathering, and white- or brown-rot decay in different combinations. After the ageing, the samples were conditioned in either 65% or 90% relative humidity (RH) until equilibrium moisture content was reached. A dynamic moisture sorption analyzer was used to monitor the sorption rate of samples subjected to a climate change from 65% to 90% RH. Scanning electron microscopy was used to study the surface morphology of the aged composites. Results showed that the artificial weathering caused cracking of the HDPE matrix at the compositesurface, as well as a wood-matrix debonding, resulting in an increased moisture sorption rate. The WPC samples subjected to white-rot decay showed the highest moisture sorption rate.

  • 22.
    Turesson, Jonas
    et al.
    Luleå University of Technology, Sweden.
    Wang, Xiaodong Alice
    Luleå University of Technology, Sweden.
    Gustafsson, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Wall heating - an energy efficient solution for wooden buildings?2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 1, p. 530-544Article in journal (Refereed)
    Abstract [en]

    Wall heating is an alternative method for residential heating that is used in a limited part of Europe. The goal of this study was to show the feasibility of this method for the Nordic market and to provide a comprehensive picture of wall heating and its functionality compared to traditional methods, i.e. radiators and floor heating. The study was conducted using literature reviews, calculations, and a survey. Simulations were made using the computer software EnergyPlus (US Department of Energy). Results showed that placement of wall heating panels in interior walls results in a lower heat loss than placement in outer walls, and that wall heating can have equal or better energy-efficiency compared to floor heating and conventional radiators. Wall heating provides a more comfortable indoor climate, in regard to dust allergies, and there is no need to remove air from each individual heating panel. A disadvantage is the need for hidden installation, which creates a problem for a safe water installation and difficulties in the attachment of fixtures. Also, the wall heating system has difficultly in handling cold drafts. Though wall heating could compete with floor heating and radiators, its disadvantages are sufficient to explain why the system is not yet used in Sweden.

  • 23.
    Veguta, Vijaya Lakshmi
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia. KTH Royal institute of technology, Sweden.
    Stevanic, Jasna S.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Lindström, Mikael E.
    KTH Royal institute of technology, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Thermal and alkali stability of sodium dithionite studied using ATR-FTIR spectroscopy2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 2, p. 2496-2506Article in journal (Refereed)
    Abstract [en]

    Sodium dithionite (Na2S2O4) may have the potential to be used as a reducing agent for the stabilization of glucomannan in kraft cooking for increased pulp yield. However, due to the fact that dithionite decomposes under the conditions of kraft pulping, studies of the effects of dithionite in kraft pulping are non-conclusive; sometimes clearly showing an increased yield, and in other studies no effect at all. The specific conditions influencing dithionite degradation are also unclear. For that reason, this study was conducted to determine the thermal and chemical stability of sodium dithionite with respect to specific factors, such as the pH, temperature, heating time, and the concentration of sodium dithionite solution. The study was performed under anaerobic conditions using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The thermal and alkali stability of the sodium dithionite solution was shown to decrease with increasing temperature, heating time, and concentration of the solution at the alkaline conditions studied. The thermal stability decreased rapidly at weak alkalinity (pH 9) as well as in high alkalinity (pH 14), whereas the sodium dithionite was rather stable at moderate alkalinity (pH 11.5 to pH 13).

  • 24.
    Wang, Xiaodong Alice
    et al.
    Luleå University of Technology, Sweden.
    Hagman, Olle
    Luleå University of Technology, Sweden.
    Sundqvist, Bror
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Material och produkter (TRm).
    Ormarsson, Sigurdur
    Linnaeus University, Sweden.
    Wang, Hui
    Mississippi State University, US.
    Niemz, Peter
    ETH Zurich, Switzerland.
    Shear strength of scots pine wood and glued joints in a cold climate2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 1, p. 944-956Article in journal (Refereed)
    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 °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 °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.

  • 25.
    Wojtasz-Mucha, Joanna
    et al.
    Chalmers University of Technology, Sweden.
    Mattsson, Cecilia
    RISE - Research Institutes of Sweden, Materials and Production, SICOMP. Chalmers University of Technology, Sweden.
    Hasani, M
    Chalmers University of Technology, Sweden.
    Theliander, H.
    Chalmers University of Technology, Sweden.
    Pretreatment and cooking of forest residues2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 4, p. 9454-9471Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to investigate the possibility of processing forest residues by chemical delignification preceded by mild steam explosion. The focus was on using soda pulping, due to its simplicity. Kraft cooking was used for comparison to improve the understanding of the separation of the complex yet promising resource. The raw material consisted of chipped branches, bark, and twigs of mixed hardwood and softwood. Analysis of the raw material proved to be challenging due to the presence of a substantial fraction of extractives. Analysis of the pulps showed that the forest residue delignification was faster than that of wood. The effects of steam explosion were evaluated with the help of composition analysis, gel permeation chromatography (GPC) for the molecular weight of lignin, and NMR for the changes in its structure. The impact of steam explosion was found to be limited, possibly due to the relatively small size of the material. 

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