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  • 51.
    Baker, Darren A.
    et al.
    RISE, Innventia.
    Bäckström, Marie
    RISE, Innventia.
    Salmen, Lennart
    RISE, Innventia.
    Schweinebarth, Hannah
    RISE, Innventia.
    Tomani, Per
    RISE, Innventia.
    Opportunities in lignin based carbon fibre2015In: NWBC 2015: The 6th Nordic Wood Biorefinery Conference, Espoo: VTT , 2015, p. 244-251Conference paper (Refereed)
    Abstract [en]

    Innventia AB's LignoBoost process enables the extraction of high purity lignin efficiently from the black liquor in kraft mills. A stream of black liquor is taken from the evaporation plant and the lignin is precipitated by acidification and filtered. The filter cake is redispersed and acidified and the resulting slurry is filtered and washed. High purity lignin can be produced at several scales, namely 10g, 1kg, 10kg and over 1,000kg. Innventia has invested significantly to demonstrate the potential of lignin as a viable feedstock for carbon fibre manufacture. Initially, the fibre melt spinning performance of the lignin is assessed using single filament melt extrusion and then melt spinning is performed at the multifilament scale, where fine fibres can be produced for conversion to carbon fibre. Oxidative thermostabilisation of the lignin fibres is carried out so that carbonisation can proceed. The effects of thermal treatment programmes and tensioning have been studied by using either thermomechanical analysis or by using test equipment specially designed to monitor carbonisation profiles with either stress or strain control. In addition, continuous processes for the conversion of lignin fibre to carbon fibre are being developed.

  • 52.
    Baker, Darren A
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Sedin, Maria
    Södra skogsägarna ekonomisk förening, Sweden.
    Landmer, Alice
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Friman, Linda
    Södra skogsägarna ekonomisk förening, Sweden.
    Echardt, Linda
    Södra skogsägarna ekonomisk förening, Sweden.
    Structural carbon fibre from kraft lignin2017In: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017: NWBC 2017, Stockholm: RISE Bioekonomi , 2017, p. 65-67Conference paper (Refereed)
    Abstract [en]

    The GreenLight consortium is working to demonstrate a biobased, renewable and economically viable carbon fibre from lignin. The aim is to provide a basis for commercial production of lignin, lignin filaments, carbon fibre and carbon fibre composites. The most difficult boundary to success in the developing lignin as a precursor for continuous filament carbon fibre has been identified as melt extrusion of lignin. The consortium is working to develop a robust melt spinning platform for use up to the 1,000 filament scale. Methodical studies have been performed to examine lignin separation from differing black liquors derived from both softwood and hardwood and assess their viability in terms of thermal, compositional and structural properties. The move will then be made to pilot scale melt spinning at the 100 filament scale. The characteristics of some kraft lignin fractions obtained from the same Sodra Monsteras softwood kraft black liquor have been studied. The lignins were manufactured in quantities of approximately 10-20kg. Several variations of the LignoBoost process were used to provide lignins with improved melt spinning properties. The lignins were of high purity, each having low carbohydrate, extractives and inorganic contents. All four lignins could be melt spun and converted to carbon fibre.

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  • 53.
    Baker, Darren
    et al.
    Baker Consulting, USA.
    Hosseinaei, Omid
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Sedin, Maria
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Papermaking and Packaging.
    Echardt, Linda
    Södra skogsägarna ekonomisk förening, Sweden.
    Capanema, Ewellyn
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Lignin-based carbon fiber: effect of softwood kraft lignin separation method on multifilament melt-spinning performance and conversion2019In: 20th International symposium on wood, fiber, and pulping chemistry, 2019Conference paper (Other academic)
    Abstract [en]

    A reference lignin separated from an industrial softwood kraft black liquor via an improved LignoBoost process was compared to four other lignins derived from the same liquor. The four lignins were produced by using a) pH-fractionation within the LignoBoost process, b) ultrafiltration of black liquor prior to the LignoBoost process, and c) solvent leaching of the reference lignin using methanol and d) ethanol.Lignin compositional characteristics and thermal properties were compared, and monofilament extrusion used to assess their potential for successful melt spinning at the 24 filament scale. The lignin prepared by ethanol leaching of the reference lignin was found to be most appropriate for potential pilot scale fibre production. This was owing to a high purity, lower comparative glass transition temperature (Tg), and good spinning performance.Thermal pretreatments of the ethanol leached lignin gave a selection of enhanced lignins which were characterized for comparison, and melt spun on pilot multifilament equipment. The enhanced lignins could be continuously melt spun giving filaments with diameters as low as 10 μm and with minimal defects. Conversion of selected filaments provided carbon fibres with a tensile strength of 1259 ± 159 MPa, tensile modulus of 67 ± 3 GPa and diameter of 7.3 ± 0.5 μm.

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  • 54.
    Balakshin, Mikhail
    et al.
    BOKU, Austria.
    Capanema, Ewellyn
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    New opportunities in the valorization of technical lignins2017In: 19th International symposium on wood, fibre and pulping chemistry, August 28 - September 1, 2017, Porto Seguro, Brazil, 2017, p. 178-182Conference paper (Refereed)
    Abstract [en]

    Commercialization of lignins for high-value products should dramatically improve the biorefinery economy and help the growing industry to overcome current economical challenges. However, this requires lignin engineering to obtain products with optimized characteristics for specific applications. This paper reviews important issues of lignin engineering, such as developments in lignin structural analysis, application of small-scale high throughput methods to evaluate lignin performance as well as new achievements in valorization of biorefinery lignins (lignin-cellulose synergism, green and cost efficient methods to upgrade crude biorefinery lignins). These recent developments allow a reconsideration of biorefinery lignins as highvalue products for different applications.

  • 55.
    Balakshin, Mikhail
    et al.
    Aalto University, Finland.
    Capanema, Ewellyn
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Huang, Zeen
    FP Innovations, Cananda.
    Sulaeva, Irina
    BOKU, Austria.
    Rojas, Orlando
    Aalto University, Finland.
    Feng, Martin
    FP Innovations, Canada.
    Rosenau, Thomas
    BOKU, Austria.
    Potthast, Antje
    BOKU, Austria.
    Recent achievement in the valorization of technical lignins2018In: The 8th Nordic Wood Biorefinery Conference: NWBC 2018 : proceedings / [ed] Hytönen Eemeli, Vepsäläinen Jessica, Espoo, 2018, p. 151-156Conference paper (Refereed)
  • 56. Barbier, C.
    et al.
    Rättö, Peter
    RISE, Innventia.
    Hornatowska, Joanna
    RISE, Innventia.
    Coating models for an analysis of cracking behavior between folded paper and creased board2012Conference paper (Refereed)
  • 57.
    Barman, Sandra
    et al.
    Chalmers University of Technology, Sweden; University of Gothenburg, Sweden.
    Fager, Cecilia
    Chalmers University of Technology, Sweden; University of G.
    Röding, Magnus
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food. Chalmers University of Technology, Sweden; University of Gothenburg, Sweden.
    Loren, Niklas
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food. Chalmers University of Technology, Sweden; University of G.
    von Corswant, Christian
    AstraZeneca, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Sweden; University of G.
    Bolin, David
    King Abdullah University of Science and Technology, Saudi Arabia.
    Rootzén, Holger
    Chalmers University of Technology, Sweden; University of Gothenburg, Sweden.
    New characterization measures of pore shape and connectivity applied to coatings used for controlled drug release2021In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 110, no 7, p. 2753-Article in journal (Refereed)
    Abstract [en]

    Pore geometry characterization-methods are important tools for understanding how pore structure influences properties such as transport through a porous material. Bottlenecks can have a large influence on transport and related properties. However, existing methods only catch certain types of bottleneck effects caused by variations in pore size. We here introduce a new measure, geodesic channel strength, which captures a different type of bottleneck effect caused by many paths coinciding in the same pore. We further develop new variants of pore size measures and propose a new way of visualizing 3-D characterization results using layered images. The new measures together with existing measures were used to characterize and visualize properties of 3-D FIB-SEM images of three leached ethyl-cellulose/hydroxypropyl-cellulose films. All films were shown to be anisotropic, and the strongest anisotropy was found in the film with lowest porosity. This film had very tortuous paths and strong geodesic channel-bottlenecks, while the paths through the other two films were relatively straight with well-connected pore networks. The geodesic channel strength was shown to give important new visual and quantitative insights about connectivity, and the new pore size measures provided useful information about anisotropies and inhomogeneities in the pore structures. The methods have been implemented in the freely available software MIST. 

  • 58.
    Battestini Vives, Mariona
    et al.
    Lund University, Sweden.
    Thuvander, Johan
    Lund University, Sweden.
    Arkell, Anders
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Lipnizki, Frank
    Lund University, Sweden.
    Low-Molecular-Weight Lignin Recovery with Nanofiltration in the Kraft Pulping Process2022In: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 12, no 3, p. 310-310Article in journal (Refereed)
    Abstract [en]

    Kraft lignin is an underutilized resource from the pulp and paper industry with the potential of being a key raw material for renewable fuels and chemicals. The separation of high-molecular-weight lignin from black liquor by ultrafiltration has been widely investigated, while the permeate containing low-molecular-weight lignin has received little attention. Nanofiltration can concentrate the low-molecular-weight lignin. This work, therefore, evaluates nanofiltration for the separation and concentration of low-molecular-weight lignin from the ultrafiltration permeate. For this study, eight flat polymeric sheet membranes and one polymeric hollow fiber membrane, with molecular weight cut-offs ranging from 100 to 2000 Da, were tested. A parametric study was conducted at 50 °C, 2.5–35 bar, and crossflow velocity of 0.3–0.5 m/s. At a transmembrane pressure of 35 bar, the best performing membranes were NF090801, with 90% lignin retention and 37 L/m2·h, and SelRO MPF-36, with 84% lignin retention and 72 L/m2·h. The other membranes showed either very high lignin retention with a very low flux or a high flux with retention lower than 80%. Concentration studies were performed with the two selected membranes at conditions (A) 50 °C and 35 bar and (B) 70 °C and 15 bar. The NF090801 membrane had the highest flux and lignin retention during the concentration studies. Overall, it was shown that the nanofiltration process is able to produce a concentrated lignin fraction, which can be either used to produce valuable chemicals or used to make lignin oil.

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  • 59. Bellani, G.
    et al.
    Lundell, F.
    Söderberg, L. Daniel
    RISE, STFI-Packforsk.
    Experimental study of the forming process: Fluid velocity and fluid-fiber interaction measurements2008In: Paper Conference and Trade Show, PaperCon '08, TAPPI Press, 2008, Vol. 2, p. 1145-1176Conference paper (Refereed)
    Abstract [en]

    A study of the flow in the direct vicinity of a forming wire and a fiber network during forming is reported. The measurements are performed with Particle Image Velocimetry in a scaled system. Index-of-refraction matching is used to gain optical access to the flow. Time resolved measurements of the flow velocity in the vertical and horizontal direction is obtained in a plane with a size of 60 × 40 fiber diameters. The spatial resolution is 2 fiber diameters. Data is obtained for three drainage velocities and two different lengths of the fibers. The relative level of the velocity fluctuations are found to decrease with drainage velocity and is higher in the flow above a network mat of shorter fibers compared to the network made of longer fibers. The size of the flow structures is obtained by spectral analysis and compared for the six cases.

  • 60.
    Bengtsson, Andreas
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Bengtsson, Jenny
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Kakkonen, Markus
    Fibrobotics Oy, Finland.
    Tanhuanpää, Olli
    Fibrobotics Oy, Finland.
    Brännvall, Elisabet
    RISE Research Institutes of Sweden, Bioeconomy and Health.
    Sedin, Maria
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Continuous Stabilization and Carbonization of a Lignin-Cellulose Precursor to Carbon Fiber2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 19, p. 16793-16802Article in journal (Refereed)
    Abstract [en]

    The demand for carbon fibers (CFs) based on renewable raw materials as the reinforcing fiber in composites for lightweight applications is growing. Lignin-cellulose precursor fibers (PFs) are a promising alternative, but so far, there is limited knowledge of how to continuously convert these PFs under industrial-like conditions into CFs. Continuous conversion is vital for the industrial production of CFs. In this work, we have compared the continuous conversion of lignin-cellulose PFs (50 wt % softwood kraft lignin and 50 wt % dissolving-grade kraft pulp) with batchwise conversion. The PFs were successfully stabilized and carbonized continuously over a total time of 1.0-1.5 h, comparable to the industrial production of CFs from polyacrylonitrile. CFs derived continuously at 1000 °C with a relative stretch of-10% (fiber contraction) had a conversion yield of 29 wt %, a diameter of 12-15 μm, a Young's modulus of 46-51 GPa, and a tensile strength of 710-920 MPa. In comparison, CFs obtained at 1000 °C via batchwise conversion (12-15 μm diameter) with a relative stretch of 0% and a conversion time of 7 h (due to the low heating and cooling rates) had a higher conversion yield of 34 wt %, a higher Young's modulus (63-67 GPa) but a similar tensile strength (800-920 MPa). This suggests that the Young's modulus can be improved by the optimization of the fiber tension, residence time, and temperature profile during continuous conversion, while a higher tensile strength can be achieved by reducing the fiber diameter as it minimizes the risk of critical defects. © 2022 The Authors. 

  • 61.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Papermaking and Packaging.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biobased Materials.
    Carbon Fibers from Lignin-Cellulose Precursors: Effect of Stabilization Conditions2019In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, no 9, p. 8440-8448Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for lightweight composites reinforced with carbon fibers (CFs). Due to its high availability and carbon content, kraft lignin has gained attention as a potential low-cost CF precursor. CFs with promising properties can be made from flexible dry-jet wet spun precursor fibers (PFs) from blends (70:30) of softwood kraft lignin and fully bleached softwood kraft pulp. This study focused on reducing the stabilization time, which is critical in CF manufacturing. The impact of stabilization conditions on chemical structure, yield, and mechanical properties was investigated. It was possible to reduce the oxidative stabilization time of the PFs from about 16 h to less than 2 h, or even omitting the stabilization step, without fusion of fibers. The main reactions involved in the stabilization stage were dehydration and oxidation. The results suggest that the isothermal stabilization at 250 °C override the importance of having a slow heating rate. For CFs with a commercial diameter, stabilization of less than 2 h rendered in tensile modulus 76 GPa and tensile strength 1070 MPa. Impregnation with ammonium dihydrogen phosphate significantly increased the CF yield, from 31-38 to 46-50 wt %, but at the expense of the mechanical properties.

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  • 62.
    Bengtsson, Andreas
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Landmér, Alice
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Norberg, Lars
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Yu, Shun
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ek, Monica
    KTH Royal Institute of Technology, Sweden.
    Brännvall, Elisabet
    KTH Royal Institute of Technology, Sweden.
    Sedin, Maria
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Carbon Fibers from Wet-Spun Cellulose-Lignin Precursors Using the Cold Alkali Process2022In: Fibers, ISSN 2079-6439, Vol. 10, no 12, article id 108Article in journal (Refereed)
    Abstract [en]

    In recent years, there has been extensive research into the development of cheaper and more sustainable carbon fiber (CF) precursors, and air-gap-spun cellulose-lignin precursors have gained considerable attention where ionic liquids have been used for the co-dissolution of cellulose and lignin. However, ionic liquids are expensive and difficult to recycle. In the present work, an aqueous solvent system, cold alkali, was used to prepare cellulose-lignin CF precursors by wet spinning solutions containing co-dissolved dissolving-grade kraft pulp and softwood kraft lignin. Precursors containing up to 30 wt% lignin were successfully spun using two different coagulation bath compositions, where one of them introduced a flame retardant into the precursor to increase the CF conversion yield. The precursors were converted to CFs via batchwise and continuous conversion. The precursor and conversion conditions had a significant effect on the conversion yield (12–44 wt%), the Young’s modulus (33–77 GPa), and the tensile strength (0.48–1.17 GPa), while the precursor morphology was preserved. Structural characterization of the precursors and CFs showed that a more oriented and crystalline precursor gave a more ordered CF structure with higher tensile properties. The continuous conversion trials highlighted the importance of tension control to increase the mechanical properties of the CFs. © 2022 by the authors.

  • 63.
    Bengtsson, Andreas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy. KTH Royal institute of technology, Sweden.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biobased Materials.
    Conditions for the stabilisation of lignin-cellulose prefibres for carbon fibre production2018In: 15th European workshop on lignocellulosics and pulp: Proceedings for poster presentations, 2018, p. 111-114Conference paper (Other academic)
    Abstract [en]

    Stabilisation of the prefibre is a time-consuming step in carbon fibre (CF) production. In this paper the stabilisation condition of dry-jet wet-spun lignin-cellulose (LC) prefibres (70:30  t%) are reported. The impact of prefibre-impregnation by ammonium dihydrogen phosphate (ADHP) and various thermal conditions were evaluated by measuring the yield and mechanical properties of the final CFs. The addition of ADHP improved the CF yields from 32-40 wt% to 45-47 wt% but had a slight negative impact on the tensile modulus (TM) whereas no significant difference in tensile strength (TS) was observed. The absence of fibre fusion and glass transition temperature (Tg) indicate successful stabilisation of all prefibres. This implies possibilities of using short stabilisation times of LC prefibres in CF production.

  • 64.
    Bengtsson, Jenny
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Bengtsson, Andreas
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ulmefors, Hanna
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Sedin, Maria
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Preventing fiber-fiber adhesion of lignin-cellulose precursors and carbon fibers with spin finish application2023In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArticle in journal (Refereed)
    Abstract [en]

    Adhesion of fibers within a spun tow, including carbon fibers and precursors, is undesirable as it may interrupt the manufacturing process and entail inferior fiber properties. In this work, softwood kraft lignin was used together with a dissolving pulp to spin carbon fiber precursors. Lignin-cellulose precursors have previously been found to be prone to fiber fusion, both post-spinning and during carbon fiber conversion. In this study, the efficiency of applying different kinds of spin finishes, with respect to rendering separable precursors and carbon fibers, has been investigated. It was found that applying a cationic surfactant, and to a similar extent a nonionic surfactant, resulted in well separated lignin-cellulose precursor tows. Furthermore, the fiber separability after carbon fiber conversion was evaluated, and notably, precursors treated with a silicone-based spin finish generated the most well-separated carbon fibers. The underlying mechanism of fiber fusion post-spinning and converted carbon fibers is discussed. 

  • 65.
    Bengtsson, Jenny
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles. Chalmers University of Technology, Sweden.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Köhnke, Tobias
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    The challenge of predicting spinnability: Investigating benefits of adding lignin to cellulose solutions in air-gap spinning2021In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 138, no 26, article id 50629Article in journal (Refereed)
    Abstract [en]

    In this study, the underlying mechanism for improved spinnability when mixing lignin and cellulose in solution was investigated. Co-processing of lignin and cellulose has previously been identified as a potential route for production of inexpensive and bio-based carbon fibers. The molecular order of cellulose contributes to the strength of the fibers and the high carbon content of lignin improves the yield during conversion to carbon fibers. The current work presents an additional benefit of combining lignin and cellulose; solutions that contain both lignin and cellulose could be air-gap spun at substantially higher draw ratios than pure cellulose solutions, that is, lignin improved the spinnability. Fibers were spun from solutions containing different ratios of lignin, from 0 to 70 wt%, and the critical draw ratio was determined at various temperatures of solution. The observations were followed by characterization of the solutions with shear and elongational viscosity and surface tension, but none of these methods could explain the beneficial effect of lignin on the spinnability. However, by measuring the take-up force it was found that lignin seems to stabilize against diameter fluctuations during spinning, and plausible explanations are discussed

  • 66.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Idström, Alexander
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Impact of non-solvents in the tetrabutylammonium acetate: dimethyl sulfoxide-cellulose system2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 19-22Conference paper (Other academic)
    Abstract [en]

    This work examines the potential of tetrabutylammonium acetate: dimethyl sulfoxide (TBAAc:DMSO) as a solvent used in a process for producing man-made cellulose fibers. The tolerance towards nonsolvents is an important step to evaluate the recyclability of the solvent. TBAAc:DMSO was in this work further confirmed to be an efficient solvent for cellulose. Non-solvent tolerance depended on cellulose concentration, TBAAc:DMSO ratio and type of non-solvent. There was no significant change in mechanical properties for filaments regenerated from solutions containing 2 wt% non-solvent compared to those spun from virgin solvent. With 4 wt% ethanol present in solution very brittle filaments were produced, not suitable for use as textile fibers.

  • 67.
    Berglin, N.
    et al.
    RISE, Innventia.
    Lovell, A.
    RISE, Innventia.
    Delin, L.
    Tormala, J.
    The 2010 reference mill for kraft market pulp2011Conference paper (Refereed)
  • 68.
    Berglin, Niklas
    et al.
    RISE, Innventia.
    Tomani, Per
    RISE, Innventia.
    Olowson, P.
    Hultberg, T.
    Persson, S.
    Experiences from feeding and co-firing of lignin powder in a lime kiln2010In: International Chemical Recovery Conference, 2010, Vol. 1, p. 175-187Conference paper (Refereed)
    Abstract [en]

    A significant part of the fossil fuel oil consumption at a pulp mill today is related to combustion in the lime kiln. Therefore, replacing fuel oil with lignin in this application has been one of the most important issues in the FRAM2 (Future Resource-Adapted Mill) research program coordinated by Innventia (formerly STFl-Packforsk) and funded by Sodra and other partners. A full-scale trial to fire lignin powder in a lime kiln was carried out at the Sodra Cell Monsteras mill, as part of the research program. In total 37 tonnes of lignin was co-fired with fuel oil. For part of the trial the kiln was operated on 100 % lignin. The experiences from the trial imply that it is possible to achieve stable and continuous operation of a lime kiln when lignin is used as the main fuel. The temperature levels in the kiln are of the same order of magnitude as when firing fuel oil or wood powder. Sulfur capture by the lime is very efficient, but there is a threshold above which S02 emissions increase rapidly. In the trial this step change occurred when going from 90 % to 100 % lignin firing. Based on the trial results, it is possible to produce lime with consistent quality when firing lignin, and the temperature reached in the burner zone is sufficient for proper sintering of the lime nodules. White liquor can be produced from the lime with the same causticizing efficiency and at the same rate as during normal operation. The mill operators also commented that it was easier to control the performance of the kiln when co-firing lignin and oil compared to the normal operation with co-firing of bark and oil.

  • 69.
    Berglin, Niklas
    et al.
    RISE, STFI-Packforsk.
    Tomani, Per
    RISE, STFI-Packforsk.
    Salman, H.
    Svärd, S. H.
    Amand, L. -E
    Pilot-scale combustion studies with kraft lignin as a solid biofuel2008In: Engineering, Pulping and Environmental Conference 2008, TAPPI Press, 2008, Vol. 4, p. 2571-2580Conference paper (Refereed)
    Abstract [en]

    Processing of kraft lignin precipitated from black liquor to produce a solid biofuel with high energy density and low ash content has been developed in research programs by STFI-Packforsk and partners. In preparation for full-scale combustion trials, tests were carried out on pilot scale in a 150 kW powder burner and in a 12 MWfluidized bed (CFB) boiler. Lignin powder could be fired in a powder burner with good combustion performance after some trimming of the airflows to reduce swirl. Lignin dried to 10 % moisture content was easy to feed smoothly and had less bridging tendencies in the feeding system than wood/bark powder. In the CFB boiler lignin was easily handled and co-fired together with bark. Although the filter cake was broken into smaller pieces and fines the combustion was not disturbed. When co-firing lignin with bark, the sulfur emission increased compared to bark firing only, but most of the sulfur was captured by calcium in the bark ash. Conventional sulfur capture with addition of limestone to the bed was also demonstrated. The sulfur content in the lignin had a significantly positive effect on reducing the alkali chloride content in the deposits, thus reducing the high temperature corrosion risk.

  • 70.
    Berglin, Niklas
    et al.
    RISE, Innventia.
    Tomani, Per
    RISE, Innventia.
    Salman, H.
    Svärd, S.H.
    Ąmand, L.-E.
    Pilot-scale combustion studies with kraft lignin in a powder burner and a CFB boiler2010In: TAPPI Journal, ISSN 0734-1415, Vol. 9, no 6, p. 24-30Article in journal (Refereed)
    Abstract [en]

    Processes have been developed to produce a solid biofuel with high energy density and low ash content from kraft lignin precipitated from black liquor. Pilot-scale tests of the lignin biofuel were carried out with a 150 kW powder burner and a 12 MW circulating fluidized bed (CFB) boiler. Lignin powder could be fired in a powder burner with good combustion performance after some trimming of the air flows to reduce swirl. Lignin dried to 10% moisture content was easy to feed smoothly and had less bridging tendencies in the feeding system than did wood/ bark powder. In the CFB boiler, lignin was easily handled and cofired together with bark. Although the filter cake was broken into smaller pieces and fines, the combustion was not disturbed. When cof ¡ring lignin with bark, the sulfur emission increased compared with bark firing only, but most of the sulfur was captured by calcium in the bark ash. Conventional sulfur capture also occurred with addition of limestone to the bed. The sulfur content in the lignin had a significantly positive effect on reducing the alkali chloride content in the deposits, thus reducing the high temperature corrosion risk. Application: This research is of interest for pulp and paper and energy and utilities companies that want to understand how kraft lignin can be used to replace fuel oil or coal in many combustion applications.

  • 71.
    Berglin, Niklas
    et al.
    RISE, Innventia.
    von Schenck, Anna
    RISE, Innventia.
    Hoffstedt, Christian
    RISE, Innventia.
    Co-production of renewable polymers and ethanol from eucalyptus-based pulp mills2012Conference paper (Refereed)
  • 72.
    Bernstad Saraiva, Anna
    et al.
    COPPE UFRJ, Brazil.
    Valle, Rogerio A. B.
    COPPE UFRJ, Brazil.
    Bosque, A.E.S., Jr.
    Fibria CElulose SA, Brazil.
    Berglin, Niklas
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    von Schenck, A.
    ÅF AB, Sweden.
    Provision of pulpwood and short rotation eucalyptus in Bahia, Brazil: Environmental impacts based on lifecycle assessment methodology2017In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 105, p. 41-50Article in journal (Refereed)
    Abstract [en]

    Environmental impacts from cultivation of eucalyptus pulpwood and short rotation eucalyptus in northeast Brazil were investigated using lifecycle assessment methodology. The assessment considers all relevant inputs and outputs, as well as direct land use changes, assuming conversion of grassland (pasture) to areas for eucalyptus plantation. Results show that production of pulpwood eucalyptus is beneficial compared to short rotation eucalyptus in relation to all assessed impact categories, except for climate change (greenhouse gas emissions = 47 kg CO2-eq. t DM−1 pulpwood eucalyptus and 35 kg CO2-eq. t DM−1 short rotation eucalyptus). Excluding emissions from direct land use changes would increase overall GWP from investigated systems with around 5–6%, and changing the assumed land-use prior to land conversion is of decisive character for overall GWP-results from the assessed eucalyptus production systems. Modeling of nutrient balances in the short rotation production system shows a potential need to increase the input of mineral fertilizer in order to compensate for nutrient losses. This would increase environmental impacts from the short rotation system, making pulpwood eucalyptus preferable in relation to all assessed impact categories.

  • 73.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Björklund Jansson, Marianne
    RISE, Innventia.
    Törngren, Per
    RISE, Innventia.
    Influence of wood extractives on calcium balance during kraft cooking2014Conference paper (Refereed)
  • 74.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Hoffstedt, Christian
    RISE, Innventia.
    Björklund Jansson, Marianne
    RISE, Innventia.
    Samuelsson, Åsa
    RISE, Innventia.
    Wadsborn, Rickard
    RISE, Innventia.
    Increasing the availability of the kraft pulp mill by the use of process simulation2012Conference paper (Refereed)
  • 75.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Jensen, Anna
    RISE, Innventia.
    Ahlroth, Mikael
    RISE, Innventia.
    New challenges regarding nonprocess elements in the liquor and lime cycle2015In: TAPPI Journal, ISSN 0734-1415, Vol. 14, no 7, p. 421-429Article in journal (Refereed)
    Abstract [en]

    Optimal performance of the green liquor plant, recausticizing plant, and lime cycle is vital for adequate white liquor availability and quality as well as for a mill's energy efficiency. Recently, various problems in the liquor and lime cycle have been frequently reported by our industrial partners, including poor performance of green liquor filters or sludge filters, decreased filterability of lime mud, increased lime kiln dead load, and poorquality white liquor. Those problems are most likely caused by an accumulation of nonprocess elements in the liquor and lime cycle due to increased mill closure, increased use of biofuels, or both. Data from the literature and earlier studies have been analyzed with regard to the occurrence and concentration of nonprocess elements in various process streams, including filtered green liquor, green liquor sludge, lime mud, and white liquor. The mineral forms in which nonprocess elements often precipitate were also studied, together with the common knowledge and rules of thumb used by mills for dealing with the problems. The literature data are compared with the newest analytical results from a sampling campaign involving several mills with varying process solutions with respect to nonprocess elements. The consequences and possible recommendations for the mills are presented. Application: Kraft pulp mills can use this information to diagnose and possibly solve problems related to nonprocess elements in day-to-day mill operation.

  • 76.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Jensen, Anna
    RISE, Innventia.
    Ahlroth, Mikael
    RISE, Innventia.
    New challenges regarding non-process elements in the liquor/lime cycle2014Conference paper (Refereed)
  • 77.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Jensen, Anna
    RISE, Innventia.
    Kulander, Ida
    RISE, Innventia.
    Scaling of manganese in kraft pulping process2014Conference paper (Refereed)
  • 78.
    Bialik, Marta
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Jensen, Anna
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Rahman, Haribur
    Chalmers university of technology, Sweden.
    Langer, Vratislav
    Chalmers university of technology, Sweden.
    Na2CO3-Na2SO4-double salt scaling in black liquor evaporators: solubility experiments in model solutions2017In: International chemical recovery conference, May 24-26, 2017, Halifax, Canada, 2017Conference paper (Refereed)
    Abstract [en]

    Scaling by Na2CO3-Na2SO4-type solids counts among the most common problems in black liquor evaporation. Previous studies have identified two double salts precipitating from Na-CO3-SO4 solutions: burkeite, Na2CO3·2Na2SO4 and (sodium sulphate) dicarbonate, Na2SO4·2Na2CO3. The latter is believed to be more prone to cause scaling. However, it has long been suspected that other double salts, with largely unknown properties, may form in this system. This work summarizes the results of precipitation studies in the Na2CO3-Na2SO4-(additive) system targeting the transition zone between burkeite and dicarbonate formation. At least one additional double salt has been identified by X-ray diffraction in both bulk crystals and in the scale. The solubility data and the equilibrium liquor compositions have been compared with earlier models

  • 79.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Moosavifar, A.
    Sedin, M.
    Theliander, H.
    Using the pitzer method to estimate the boiling point rise in black liquor solutions2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 2, p. 172-182Article in journal (Refereed)
    Abstract [en]

    The boiling point rise (elevation) of aqueous industrial solutions is often of significant importance for the design of process conditions, equipment, heat balances, etc. However, few rigorous methods exist for predicting boiling point elevation in complex, multicomponent, electrolyte solutions. An example of such a solution is the black liquor obtained in kraft pulp production: a complex mixture of organic and inorganic ions including Na +, K + OH -, HS - C0 3 2- S0 4 2- S 20 3 2- CH 3COO - various phenolates and many more. This work shows one application of the semi-empirical Pitzer method to the theoretical prediction of the boiling point rise in industrial black liquor solutions. The values of the boiling point elevation were measured in two series of black liquors from representative Swedish mills, including both the original and lignin-lean black liquor at different solid contents. The results show a good agreement between experimental and predicted values at low to moderate solid content, and good qualitative prediction at high solid content.

  • 80.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Sedin, Maria
    Theliander, H.
    Application of the pitzer method in estimating the properties of black liquor solutions: A summary2010In: International Chemical Recovery Conference, 2010, Vol. 2, p. 16-23Conference paper (Refereed)
    Abstract [en]

    The Pitzer method for calculating activity coefficients in aqueous electrolyte solutions has been widely applied to modeling the properties of numerous industrial systems. Its use in hot, concentrated solutions, an example being black liquor from kraft pulping process, has nevertheless been limited mainly due to a lack of suitable interaction parameters. This paper summarizes our work in implementing the Pitzer method into modeling of double salt solubilities and boiling point rise in industrial black liquors. Two solubility models: for burkeite, Na 2Co 22Na 2S0 4 and for (sodium sulfate) dicarbonate, 2Na 2CO 3Na 2S0 4 were developed based on literature and experimental data, respectively. Boiling point rise was modeled in two types of black liquor: ordinary and lignin-lean after a lignin precipitation stage. The paper also presents our study on a method for estimating new Pitzer interaction parameters in hot solutions of sodium lactate using the boiling point rise data.

  • 81.
    Bialik, Marta
    et al.
    RISE, Innventia.
    Wadsborn, Rickard
    RISE, Innventia.
    Karlholm, Ingeli
    RISE, Innventia.
    Berglin, Niklas
    RISE, Innventia.
    Assessment of scaling risk in a pressurized black liquor gasification pilot plant2010In: International Chemical Recovery Conference, 2010, Vol. 1, p. 279-286Conference paper (Refereed)
    Abstract [en]

    Black liquor gasification is considered as an interesting alternative to the recovery boiler-based process of green liquor production. Although the handling of the smelt in the two separate processes is similar, the final concentration and temperature of the green liquor from gasification might both be higher. This, together with the S/Na split acquired by the gasification unit, may increase the risk of scaling of slightly soluble salts during green liquor handling. This work uses a previously developed solubility model for sodium carbonate, calcium carbonate and pirssonite, CaCO 3·Na 2CO 3·H 20 in order to evaluate the scaling risk in green liquor obtained from the gasification process. The model, originally based on both gasification green liquor and regular green liquor data, was verified against new samples of green liquor from an experimental gasification unit in Sweden. During the conducted sampling campaign, the following process parameters were varied in order to establish their influence on the final liquor composition: temperature and load of the gasifier, mixing rate in the smelt dissolver, and composition of the dilution water. It has been found that varying the process parameters within the normal operational limits has a relatively small influence, on the composition of the green liquor. The risk for pirssonite precipitation in gasification green liquor was estimated as relatively low, which is consistent with earlier findings. The calculated values of the apparent solubility product were also consistent with previous results.

  • 82. Bjurhager, I.
    et al.
    Olsson, Anne-Mari
    RISE, Innventia.
    Zhang, B.
    Gerber, L.
    Kumar, M.
    Berglund, Lars A.
    Burgert, I.
    Sundberg, B.
    Salmen, Lennart
    RISE, Innventia.
    Ultrastructure and mechanical properties of populus wood with reduced lignin content caused by transgenic down-regulation of cinnamate 4-hydroxylase2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 9, p. 2359-2365Article in journal (Refereed)
    Abstract [en]

    Several key enzymes in lignin biosynthesis of Populus have been down-regulated by transgenic approaches to investigate their role in wood lignification and to explore their potential for lignin modification. Cinnamate 4-hydroxylase is an enzyme in the early phenylpropanoid pathway that has not yet been functionally analyzed in Populus. This study shows that down-regulation of cinnamate 4-hydroxylase reduced Klason lignin content by 30% with no significant change in syringyl to guaiacyl ratio. The lignin reduction resulted in ultrastructural differences of the wood and a 10% decrease in wood density. Mechanical properties investigated by tensile tests and dynamic mechanical analysis showed a decrease in stiffness, which could be explained by the lower density. The study demonstrates that a large modification in lignin content only has minor influences on tensile properties of wood in its axial direction and highlights the usefulness of wood modified beyond its natural variation by transgene technology in exploring the impact of wood biopolymer composition and ultrastructure on its material properties.

  • 83.
    Bjärestrand, Annika
    RISE, Innventia.
    Upgrading of recycled pulp quality by fractionation and selective refining2016Conference paper (Other academic)
  • 84.
    Bjärestrand, Annika
    et al.
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Upgrading recycled pulp quality by fractionation and selective refining2016In: International Paperworld IPW, ISSN 1615-1720, Vol. 2016-January, no 12, p. 40-44Article in journal (Other academic)
    Abstract [en]

    As recycling rates increase and the consumption of graphic papers decrease it becomes more and more difficult to maintain the recycled fibre quality. Also, increasing ash content in the recycled pulp contributes to the strength challenge ahead for the paper and board producers. The fractionation of recycled fibre in this study was made in order to investigate possible routes for upgrading the recycled pulp strength. A recycled pulp for containerboard was fractionated in pilot scale using a pressure screen and hydrocydones. The pulp was first fractionated using a micro-perforated screen basket into a short fraction, with high ash and fines content, and a long fibre fraction. The following hydrocyclone fractionation of the screen short fraction resulted in a fine fraction with fibrillar fines and a coarse fraction containing low bonding fines and fibre fragments together with most of the ash. The short coarse fraction also had a high dirt content. When the screen long fibre fraction was split in the hydrocyclone fractionation, a fine fibre fraction containing good bonding fibres and fines and a coarse fibre fraction with coarse low bonding fibres were obtained. The coarse long fibre fraction was upgraded, to a strength level comparable to the good bonding fine fraction, by refining with an energy input of only 24 kWh/t calculated on the whole pulp. This selective refining of the coarse long fibre fraction resulted in an improvement of the pulp strength by 20 % when the pulp fractions were mixed back together in the same proportion as they had been separated. Further strength was gained when the low bonding short coarse fraction with high ash content was removed. This study showed that a recycled pulp can be upgraded by selective and appropriate treatment of the different streams, with different properties, produced in a fractionation process.

  • 85.
    Björk, Elisabeth
    et al.
    RISE, Innventia.
    Athley, Karin
    RISE, Innventia.
    Thomsson, Lars
    RISE, Innventia.
    Advanced techniques to study filler flocs in high shear environments2012Conference paper (Refereed)
  • 86.
    Björk, Elisabeth
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Bouveng, Mikael
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Holmqvist, Claes
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Vomhoff, Hannes
    Holmen AB, Sweden.
    Fibre-based strength aids for increased board stiffness2019In: PaperCon 2019: proceedings, TAPPI Press, 2019, article id PF2.3Conference paper (Other academic)
    Abstract [en]

    A pilot scale study has been made of the concept of adding fibre-based strength agents (fines enriched (FE)-pulp or highly refined (HR)-pulp) in a board middle ply containing chemithermomechanical bleached pulp (CTMP) in order to increase bending stiffness of the board while maintaining Z-strength. It has been demonstrated that the bending stiffness of a sheet consisting of a top ply and a CTMP based middle ply could be improved by increasing the CTMP fraction and preventing Z-strength loss via addition of a fibre based strength agent. Compared with the reference pulp, both Z-strength and bulk increased for three of the compositions, namely 65% CTMP with 5% strength agent of either FE or HR type and 85% CTMP with 10% HR-pulp. FE-pulp was found to be more efficient than HR-pulp concerning bending stiffness improvement. While the highly-refined fibres of the strength agents had a negative effect on the drainage resistance and press dryness, an increased share of CTMP increased the press dryness linearly. FE-pulp and HR-pulp had the same impact on press dryness. Press solids could be improved by approximately 2% without significantly reducing the bulk by increasing press loads.

  • 87.
    Björk, Elisabeth
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Bouveng, Mikael
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Vomhoff, Hannes
    Holmen AB, Sweden.
    Fines-enriched pulp as a strength agent in a CTMP middle ply2018In: PaperCon 2018: Shaping the future through innovation, TAPPI , 2018, p. 741-760, article id PA5.2Conference paper (Refereed)
    Abstract [en]

    The objective of this pilot scale trial, was to evaluate fines-enriched pulp (FE-pulp) as a strength agent in amiddle ply of a board product.A typical CTMP-based middle ply was produced on the FEX pilot paper machine. The stock consisted of CTMP,refined hardwood and softwood pulp, and filler. FE-pulp as strength agent was compared with glue pulp, ahighly refined chemical pulp. FEX sheets and hand sheets made of pulp mixtures were evaluated. Also, thedewatering and pressing conditions on the paper machine were compared.The results confirmed the results of earlier experiments with handsheets; FE-pulp used as strength agent showedto be twice as efficient as glue pulp regarding strength properties without impairing the bulk. Further, thedewatering conditions and press dryness's on the paper machine was comparable at these additions. Thus, allthese results imply that addition of FE-pulp can replace the double amount of glue pulp as a strength agent.

  • 88.
    Björk, Elisabeth
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Bouveng, Mikael
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Vomhoff, Hannes
    Holmen AB, Sweden.
    Production of pulps with an extremely high fines content for use as strength agent2018In: PaperCon 2018: Shaping the future through innovation, TAPPI , 2018, article id PA5.1Conference paper (Refereed)
    Abstract [en]

    The objective was to optimize the production of fines-enriched pulp (FE-pulp) from chemical pulp.The first trial was a continuous production of FE-pulp with unbleached and bleached never-dried softwood. Thepulp was refined using a JC00 equipped with SF filling, and screened with a micro-perforated screen basket with250 μm diameter holes, but the produced FE-pulp got low concentration, below 3 g/l.The second trial aimed at optimised conditions, using dried bleached softwood. Three fillings, microbar, AA andFF were evaluated in a JC01 refiner, where microbar was most energy efficient. Microbar and AA reachedtargeted FE-pulp concentration, 10 g/l. The refined pulps were screened with different hole diameters, where, asexpected, larger hole diameters resulted in higher concentration but also lower fines content in the FE-pulps.The last trial, the microbar filling was evaluated for never-dried softwood pulp, unbleached and bleached. Now,the refining of unbleached softwood gave 3 times more fines per kWh/ton compared with first trial.These trials demonstrated the importance of the right refining conditions regarding effect of refiner and type offilling to achieve glue-pulp with high enough fines content. With the right conditions, it was possible to produceFE-pulp with high concentration at moderate energy consumption.

  • 89.
    Björk, Elisabeth
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Bouveng, Mikael
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Vomhoff, Hannes
    Engstrand, Per
    Use of fines-enriched chemical pulp to increase CTMP strength2021In: TAPPI Journal, ISSN 0734-1415, Vol. 20, no 4, p. 255-263Article in journal (Refereed)
    Abstract [en]

    In this study, fines-enriched pulp (FE-pulp)-the fine fraction of highly-refined kraft pulp-was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomech. pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets. The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chem. pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability.

  • 90.
    Björk, Elisabeth
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging. Mittuniversity, Sweden.
    Bouveng, Mikael
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Vomhoff, Hannes
    Holmen AB, Sweden.
    Engstrand, Per
    Mittuniversity, Sweden.
    Use of fines-enriched chemical pulp to increase CTMP strength2021In: TAPPI Journal, ISSN 0734-1415, Vol. 20, no 4, p. 255-263Article in journal (Refereed)
    Abstract [en]

    In this study, fines-enriched pulp (FE-pulp)-the fine fraction of highly-refined kraft pulp-was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomechanical pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets. The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chemical pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability. Application: In this study, we show how the strength of a CTMP sheet can be improved by adding fine material from kraft pulp.

  • 91.
    Björk, Elisabeth
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Muhic, Dino
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Hagman, Anton
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Halonen, Helena
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Stock Preparation as a Key Operation for Making High-Quality Wet Moulded Fibre Products2022In: TAPPICon Conference 2022, TAPPI Press , 2022Conference paper (Refereed)
    Abstract [en]

    In the global pursuit for sustainable packaging solutions, usage of different paper raw material is one of the key components to fulfil the goal. Moulded fibre products allow usage of different fibre raw material, although for today, with some restrictions. For example, recycled fibre is of varying quality and can be a challenging material to use for thermoformed wet moulding applications. Further, CTMP strength potential should be further utilized for this application. In both cases, the stock preparation is crucial. The relationship between fibre type, stock preparation, processing and performance needs to be investigated to define how to best produce high-quality wet moulded fibre products using a specific fibre type. To be able to study this a laboratory equipment for manufacturing of high-quality wet moulded fibre products has been set up. Moreover, two test methods to evaluate properties important for trays have been developed; one to evaluate how much load the tray can take and one to evaluate how much the tray will warp during handling. Together with an optimised stock preparation for different fibre raw materials studies can be performed, which aim at increased usage of fibre qualities such as recycled fibre or CTMP for high-quality moulded fibre products. 

  • 92.
    Björk, Elisabeth
    et al.
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Bouveng, Mikael
    RISE, Innventia.
    Production of a fine fraction using micro-perforated screens2015In: Paper Conference and Trade Show (PaperCon 2015), TAPPI Press, 2015, Vol. 1, p. 543-560Conference paper (Refereed)
  • 93.
    Björk, Elisabeth
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy.
    Vomhoff, Hannes
    RISE - Research Institutes of Sweden, Bioeconomy.
    Bouveng, Mikael
    RISE - Research Institutes of Sweden, Bioeconomy.
    Usage of Fines-enriched pulp to increase strength in CTMP2017In: Paper Conference and Trade Show, PaperCon 2017: Renew, Rethink, Redefine the Future, TAPPI Press, 2017, Vol. 3, p. 1607-1631Conference paper (Other academic)
    Abstract [en]

    Fines-enriched pulp (FE-pulp) was benchmarked against glue pulp as strength agent in eucalypt CTMP. FE-pulp was produced by combining high intensity multiple-pass refining with a fractionation in a microperforated screen basket. The fraction passing through the holes of the screen is the FE-pulp. The FE-pulp comprises of secondary fines, created in the refiner, and flexible, fibrillated highly-refined fibres or fibre fragments. Glue pulp is highly refined kraft pulp, commonly added as a strength agent in middle plies of board products, or between plies to increase the plybond. Equal amounts of FE-pulp and glue pulp were added to the original CTMP as well as to washed CTMP, where most of the CTMP-fines had been removed. The effects of the strength agents were evaluated using laboratory sheets. Both glue pulp and FE-pulp increased the strength of the CTMP sheets. The bulk of the sheets decreased however. When 5 % FE-pulp was added, the tensile index increased by more than 50 %, and the tensile energy absorption and z-strength increased by more than 100 %. FE-pulp proved to be twice as effective as glue pulp. The addition of 5 % FE-pulp resulted in the same relative strength increase as an addition of 10 % glue pulp. The washed CTMP lost all strength when the CTMP-fines content was reduced from 17 % to 3% through washing. The addition of 5 % FE-pulp restored the strength values, and at a higher bulk. The drainability in terms of CSF of that stock was much higher when compared to the original pulp.

  • 94.
    Björk, Elisabeth
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging. Mid Sweden University, Sweden.
    Vomhoff, Hannes
    Holmen, Sweden.
    Engstrand, Per
    Mid Sweden University, Sweden.
    Production of fines from refined kraft pulp by fractionation with micro-perforated screens2021In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 36, no 3, p. 456-Article in journal (Refereed)
    Abstract [en]

    The objective in this work was to obtain a fine fraction of kraft pulp, with as high concentration as possible, in a pilot-scale fractionation with micro-perforated screen baskets. The influence of screen basket surface, hole size, feed concentration, pulp type and refining segment design was investigated. The results showed that a smooth screen basket surface improved the fractionation efficiency of the unrefined pulp compared to a profiled screen basket, despite a larger hole size. A significantly higher fine fraction concentration was obtained when using refined hardwood pulp compared to when using softwood pulp, which was explained with its lower average fibre length and narrower and thus more flexible fibre fragments. The pilot trials also showed that the screening process could be operated at feed concentrations similar to those directly after a refiner, 30-40 g/l. This was demonstrated in a process layout with partial recirculation where a refiner and a micro-perforated screen basket were operated in series in pilot scale. 

  • 95.
    Björk, Elisabeth
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Vomhoff, Hannes
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Lindgren, Margareta
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Single-stage hydrocyclone fractionation of refined bleached softwood pulp2017In: Paper Conference and Trade Show, PaperCon 2017: Renew, Rethink, Redefine the Future, 2017, Vol. 2, p. 878-905Conference paper (Other academic)
    Abstract [en]

    Refined bleached chemical softwood was fractionated using a hydrocyclone in a fine and a coarse fraction. The trials were done at three inject concentrations, three coarse fraction volume ratios, and with pulps refined with two refining levels.

    A large difference in sheet properties between fine and coarse fraction was observed. Compared with the feed pulp, the relative change in the sheet properties increased more in the fine fractions than it decreased in the coarse fractions. Increased fines proportion had a positive effect on all properties up to a certain level when a further improvement could not be observed. Interestingly, the fine fractions of both refining levels reached the same absolute strength level, both for the tensile properties and z-strength. The fine fractions at the highest coarse fraction mass ratios contained more fines, and the mean fibre was shorter and narrower. This led to higher density but also a decrease of the stretch-at-break and z-strength values.

    When comparing these results with previous fractionation results for unrefined pulp, it was found that inject concentration did not have a large effect on thickening in the present study. As for the refined pulp, the tensile index increased with fines proportion for the unrefined pulp, however, only up to a certain fines proportion where a maximum values was reached. The increase was larger for the refined pulps which had higher fines proportion.

  • 96.
    Björklund Jansson, Marianne
    et al.
    RISE, Innventia.
    Bialik, Marta
    RISE, Innventia.
    Törngren, Per
    RISE, Innventia.
    New insights into soap solubility and separation during kraft cooking2014Conference paper (Refereed)
  • 97. Bohlin, E.
    et al.
    Coppe, L.
    RISE, Innventia.
    Johansson, C.
    Edström, P.
    Modelling of brightness decrease of coated cartonboard as an effect of calendering: Microroughness and effective refractive index aspects2010In: 11th Advanced Coating Fundamentals Symposium Proceedings: The Latest Advances in Coating Research and Development, 2010, p. 51-65Conference paper (Refereed)
    Abstract [en]

    Calendering of coated paper leads to a brightness decrease. The mechanism for this is not clear, although it has been discussed in the past. One common explanation is that the porosity of the coating layer decreases and hence scattering. By comparing simulated and measured results this paper shows that modifications of the surface properties account for the brightness decrease of GCC coated substrates with calendering. The effect of a deformable cartonboard substrate is investigated here and compared to a less deformable plastic film substrate. From simulations based on a two-layer Kubelka-Munk model, it is shown that the brightness decrease of the cartonboard due to calendering has a negligible contribution to the brightness decrease of the coated cartonboard. The brightness decrease was similar for coated plastic film and coated cartonboard. The thickness of GCC coated plastic films was not affected by calendering irrespectively of the pigment and latex size distribution. Monte Carlo light scattering simulations, taking into account the measured decrease of surface microroughness and increased effective refractive index, showed that surface modifications accounted for most of the observed brightness decrease of the GCC coated substrate, whereas the bulk scattering and absorption coefficients were not affected by calendering. It is also shown that the scattering coefficient is significantly dependent on the coat weight whereas the physical absorption coefficient is not.

  • 98.
    Borrega, Marc
    et al.
    Aalto university, Finland ; VTT Technical Research Centre of Finland Ltd, Finland.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Ahvenainen, Patrik
    University of Helsinki, Finland.
    Ceccherini, Sara
    Aalto university, Finland.
    Maloney, Thaddeus
    Aalto university, Finland.
    Rautkari, Lauri
    Aalto university, Finland.
    Sixta, Herbert
    Aalto university, Finland.
    Birch wood pre-hydrolysis vs pulp post-hydrolysis for the production of xylan-based compounds and cellulose for viscose application2018In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 190, p. 212-221Article in journal (Refereed)
    Abstract [en]

    Hydrothermal treatments of birch wood and kraft pulp were compared for their ability to extract the xylan and produce viscose-grade pulp. Water post-hydrolysis of kraft pulp produced a high-purity cellulosic pulp with lower viscosity but higher cellulose yield than traditional pre-hydrolysis kraft pulping of wood. Post-hydrolysis of pulp also increased the crystallite dimensions and degree of crystallinity in cellulose, and promoted a higher extent of fibril aggregation. The lower specific surface area in post-hydrolyzed pulps, derived from their larger fibril aggregates, decreased the accessibility of –OH groups. However, this lower accessibility did not seem to decrease the pulp reactivity to derivatizing chemicals. In the aqueous side-stream, the xylose yield was similar in both pre- and post-hydrolysates, although conducting post-hydrolysis of pulp in a flow-through system enabled the recovery of high purity and molar mass (∌10 kDa) xylan for high-value applications.

  • 99.
    Bostan, Lars
    et al.
    Faserinstitut Bremen E.V, Germany.
    Hosseinaei, Omid
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Fourné, Renate
    FOURNÉ Maschinenbau GmbH, Germany.
    Herrmann, Axel
    Faserinstitut Bremen E.V, Germany; University of Bremen, Germany.
    Upscaling of lignin precursor melt spinning by bicomponent spinning and its use for carbon fibre production2021In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 379, no 2209, article id 20200334Article in journal (Refereed)
    Abstract [en]

    Upscaling lignin-based precursor fibre production is an essential step in developing bio-based carbon fibre from renewable feedstock. The main challenge in upscaling of lignin fibre production by melt spinning is its melt behaviour and rheological properties, which differ from common synthetic polymers used in melt spinning. Here, a new approach in melt spinning of lignin, using a spin carrier system for producing bicomponent fibres, has been introduced. An ethanol extracted lignin fraction from LignoBoost process of commercial softwood kraft black liquor was used as feedstock. After additional heat treatment, melt spinning was performed in a pilot-scale spinning unit. For the first time, biodegradable polyvinyl alcohol (PVA) was used as a spin carrier to enable the spinning of lignin by improving the required melt strength. PVA-sheath/lignin-core bicomponent fibres were manufactured. Afterwards, PVA was dissolved by washing with water. Pure lignin fibres were stabilized and carbonized, and tensile properties were measured. The measured properties, tensile modulus of 81.1 ± 3.1 GPa and tensile strength of 1039 ± 197 MPa, are higher than the majority of lignin-based carbon fibres reported in the literature. This new approach can significantly improve the melt spinning of lignin and solve problems related to poor spinnability of lignin and results in the production of high-quality lignin-based carbon fibres. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'. © 2021 The Author(s).

  • 100. Bradley, E. L.
    et al.
    Honkalampi-Hämäläinen, U.
    Weber, A.
    Andersson, M. A.
    Bertaud, F.
    Castle, L.
    Dahlman, O.
    RISE, STFI-Packforsk.
    Hakulinen, P.
    Hoornstra, D.
    Lhuguenot, J. -C
    Mäki-Paakkanen, J.
    Salkinoja-Salonen, M.
    Speck, D. R.
    Severin, I.
    Stammati, A.
    Turco, L.
    Zucco, F.
    von Wright, A.
    The BIOSAFEPAPER project for in vitro toxicity assessments: Preparation, detailed chemical characterisation and testing of extracts from paper and board samples2008In: Food and Chemical Toxicology, ISSN 0278-6915, E-ISSN 1873-6351, Vol. 46, no 7, p. 2498-2509Article in journal (Refereed)
    Abstract [en]

    Nineteen food contact papers and boards and one non-food contact board were extracted following test protocols developed within European Union funded project BIOSAFEPAPER. The extraction media were either hot or cold water, 95% ethanol or Tenax, according to the end use of the sample. The extractable dry matter content of the samples varied from 1200 to 11,800 mg/kg (0.8-35.5 mg/dm2). According to GC-MS the main substances extracted into water were pulp-derived natural products such as fatty acids, resin acids, natural wood sterols and alkanols. Substances extracted into ethanol particularly, were diisopropylnaphthalenes, alkanes and phthalic acid esters. The non-food contact board showed the greatest number and highest concentrations of GC-MS detectable compounds. The extracts were subjected to a battery of in vitro toxicity tests measuring both acute and sublethal cytotoxicity and genotoxic effects. None of the water or Tenax extracts was positive in cytotoxicity or genotoxicity assays. The ethanol extract of the non-food contact board gave a positive response in the genotoxicity assays, and all four ethanol extracts gave positive response(s) in the cytotoxicity assays to some extent. These responses could not be pinpointed to any specific compound, although there appeared a correlation between the total amount of extractables and toxicity.

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