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  • 51.
    Granberg, Hjalmar
    et al.
    RISE, Innventia.
    Gustafsson Coppel, Ludovic
    RISE, Innventia.
    Eita, Mohamed
    RISE, Innventia.
    De Mayolo, Eduardo Antunez
    RISE, Innventia.
    Arwin, Hans
    RISE, Innventia.
    Wågberg, Lars Göran
    RISE, Innventia.
    Dynamics of moisture interaction with polyelectrolyte multilayers containing nanofibrillated cellulose2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 496-499Article in journal (Refereed)
    Abstract [en]

    Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after ~20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction with no separate water film on top. The results provide important understanding for the design of NFC based LbL films for visual moisture sensors and interactive security paper.

  • 52. Grön, J
    et al.
    Dahlvik, P
    Ström, G
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Influence of starch modification on the chemical composition and structure of coated layers1998In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 13, p. 119-123Article in journal (Refereed)
    Abstract [en]

    Colloid interactions in clay coating colors have benn modified with either an anionic or a cationized starch cobinder. This paper reports on surface chemistry and structure of the coated papers as well as print gloss and ink demand. The thickness of the surface layer and the top layer of the coating was defined by the analyzing equipment and was about 0.01μm and a few μm respectively. The internal structure of the coating layer was characterized with air leak porous layer structure. These coatings also had much higher amounts of starch in the surface layer, while the coatings containig anionic starch had a higher content of latex in the top layer. The ink requirement to reach a certain print gloss was higher for the aggregated coatings i.e. those containing cationized starch. A higher ink demand was initiated by a more porous layer structure and a rougher surface.

  • 53.
    Hagman, Anton
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Nygårds, Mikael
    RISE, Innventia.
    Short compression testing of multi-ply paperboard, influence from shear strength2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 1, p. 123-134Article in journal (Refereed)
    Abstract [en]

    The influence of the through-thickness shear strength profiles on the short span compression test was examined. This was done both with experiments and finite element simulations on five industrial produced paperboards. It was concluded that the short span compression test is governed by in-plane stiffness and through thickness delamination. The delamination damage was in turn dependent on the local transverse shear strength and in-plane stiffness gradients. Furthermore, it was concluded that the pre-delamination mechanisms were elastic. Finally it was possible to alter the results from the test by altering the shear strength of the paperboard; this should be done uniformly over the entire middle ply of the board if an increased SCT value was what was sought after.

  • 54.
    Hedlund, Artur
    et al.
    RISE, Swerea, IVF.
    Köhnke, Tobias
    RISE, Swerea, IVF.
    Theliander, H.
    Chalmers University of Engineering, Sweden.
    Coagulation of EmimAc-cellulose solutions: Dissolution-precipitation disparity and effects of non-solvents and cosolvent2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 1, p. 32-42Article in journal (Refereed)
    Abstract [en]

    Coagulation values (CVs) of cellulose/1-ethyl-3-methylimidazolium acetate (EmimAc)/dimethyl-sulfoxide (DMSO) solutions for water, ethanol (EtOH) and 2-propanol (2-PrOH) were measured by using a light-scattering technique. Expressed in moles per mole, CVs of H2O were roughly twice as high as the CVs of EtOH and 2-PrOH at equal cellulose concentration for EmimAc solutions without the addition of a cosolvent. We explain this observation mainly in terms of alcohol alkyl chains efficiently obstructing EmimAc anions, preventing anions from simultaneously interacting with cellulose hydroxyls. DMSO was found to mitigate the coagulating effect of water and, to a lesser extent, the effect of alcohols. The explanation may be the different enthalpies of mixing for water and alcohols, with DMSO. An explanation on a more practical level, is based on how the solvatochromic α and β parameters change due to small amounts of the different non-solvents. Small additions of methanol induce disproportionately large changes from basic towards acidic properties for DMSO, meanwhile, the same stoichiometric addition of water induces only minor changes. Precipitation occurred at concentrations of non-solvent much higher than the concentrations that limit dissolution. The most likely explanation for this is a metastable region in the phase diagram. It was also seen that the typically observed inhibitive effect of high Mw on solubility during dissolution did not apply to precipitation. 

  • 55.
    Hii, Collin
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of MFC on the pressability and paper properties of TMP and GCC based sheets2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 388-396Article in journal (Refereed)
    Abstract [en]

    Different qualities of microfibrillated cellulose (MFC) were blended with thermomechanical pulp (TMP) and ground calcium carbonate (GCC) filler. The addition of MFC reduced the drainage of the pulp suspension but improved strength properties. Wet pressing experiments showed that optimal use of MFC and filler could enhance the strength and optical properties without reducing the solids content after wet pressing. Field-emission scanning electron microscopy (FESEM) revealed that MFC adsorbed onto and contributed to the bonding of the filler particles and fibres. The MFC binds the filler-MFC-fines aggregates to the fibre network and partially filled the pore network. As a result, MFC addition increased the air resistance and internal bonding of the sheet.

  • 56.
    Hii, Collin
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of Newsprint furnish composition and sheet structure on wet pressing efficiency2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 4, p. 790-797Article in journal (Refereed)
    Abstract [en]

    The dewatering ability and wet sheet structure after pressing was studied using a dynamic wet pressing simulator in combination with electron microscopy and image analysis. Deinked pulp (DIP) that contains 5% ash dewaters more easily than thermo-mechanical pulp (TMP) when pressed with single roll pulse. The in-plane moisture flow (crushing) in DIP samples started at higher peak pressure and higher solids content compared to TMP samples. The TMP sample showed higher springback after wet pressing compared to DIP samples. When both TMP and DIP samples were designed to have a higher amount of small pores at the dewatering side surface layers, the samples with coarser TMP pulp could achieve similar dryness as DIP samples when pressed with higher nip pressure. In addition, the DIP samples with higher number of small pores in the outermost 10 μm thick surface layer in the dewatering side resulted in lower dryness after pressing with a single roll pulse. The effect of filler distribution in paper z-direction on dryness and sheet structure after wet pressing using an 8 milliseconds roll pulse was also studied. In this study the distribution of filler does not affect the maximum achievable dryness (41%) after wet pressing when the total amount of filler in the sheets remains constant, 13.5%. In addition, the samples with more filler in the dewatering layer dewater more easily and yield the maximum achievable dryness (40%) after wet pressing at lower nip pressure (2.5 MPa) when compared to samples made from TMP (36% at 4.4 MPa) and DIP pulps (40% at 4.9 MPa).

  • 57.
    Hii, Collin
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The web structure in relation to the furnish composition and shoe press pulse profiles during wet pressing2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 4, p. 798-805Article in journal (Refereed)
    Abstract [en]

    This study shows that wet-pressing TMP and DIP with a shoe press pulse may yield similar after-press solids, provided that an adequate shoe pulse length with similar pressure profile is applied. A wet web with more porous structure in the sheet dewatering (felt) layer seems to contribute to the increased dewatering during wet pressing. In addition, a shoe press pulse with high peak pressure at the end yields higher solids content after wet-pressing and higher bulk compared to a pulse with a peak pressure in the beginning. The increased dewatering during wet-pressing implies a reduction of steam consumption in the dryer.

  • 58.
    Hill, Jan
    et al.
    QualTech AB, Sweden.
    Johansson, Lars
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Mörseburg, Kathrin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    ATMP pulping of Norway spruce: Pulp property development and energy efficiency2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 1, p. 70-86Article in journal (Refereed)
    Abstract [en]

    ATMP pilot refining trials on Norway spruce were conducted. The ATMP configuration consists of selective wood disintegration and targeted application of chemicals when defibration already is initiated in order to achieve energy-efficient final fibre separation and development. ATMP was compared to TMP and RTS. The TMP like character was maintained despite of differences in pre-treatment, chemicals and primary stage refining energies. The fractional composition of the pulps was, however, altered. Bauer McNett R14 fraction exhibited the largest differences followed by P200 fraction. Thus different process alternatives produced pulps with different fingerprints. The amount of the R14 fibres is important as these tend to cause surface roughness impairing printability. Regardless of strategy, the ATMP pulp properties at equal tensile index (44 Nm/g) were equal or superior to those achieved by TMP or RTS refining. The main difference was the required specific energy input, ranging from 1.71 (TMP) to 1.05 MWh/BDT (ATMP with bisulphite addition). Primary stage refining was explored from multiple trials with the same process configuration and chemistry. The higher the specific energy applied the better is the energy efficiency. Furthermore established refining theories appear inadequate in describing the differences between process alternatives with respect to energy efficiency and pulp property development.

  • 59.
    Hyll, Kari
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Size and shape characterization of fines and fillers: A review2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 3, p. 466-487Article in journal (Refereed)
    Abstract [en]

    Many properties of fines and fillers are dependent on their size and shape. This review is on the literature on size and shape characterization of fines and fillers. It takes into account measurement techniques of particle width, length, equivalent diameter, area, and shape/morphology. The advantages and limitations of different methods are discussed. Measurement of other particles properties, e.g., optical, chemical or rheological, were not included in the review. Size and shape characterization methods can be roughly divided into gravimetric and non-gravimetric methods. Gravimetric measurements methods account for all particles in the sample, but give only indicative size and shape information. Non-gravimetric methods usually give more direct size and shape information, but only account for particles larger than the resolution of the instrument. Additionally, measuring both larger and smaller particles simultaneously is rarely possible. An implication is that current analysers fail to measure a larger share of the sample, for example fibrils, which have a high impact on product properties. Of the reviewed measurement techniques, flow microscopy had the highest potential. Based on instruments found in other application areas, possible developments for flow microscopes include multiwavelength illumination and sensors, fluorescent staining, and hydrodynamic focusing.

  • 60.
    Hyll, Kari
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Björk, Elisabeth
    RISE, Innventia. Mid Sweden University, Sweden.
    Vomhoff, Hannes
    RISE, Innventia.
    Flow imaging characterisation of morphological changes of chemical pulp due to refining2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 411-421Article in journal (Refereed)
    Abstract [en]

    The influence of the refining process on the morphological changes of a chemical softwood pulp was investigated. The Voith LR40 industrial-like laboratory low consistency refiner was used, where the pulp was refined with five refining segments with differences in bar widths, groove widths, and cutting angles. The refined pulp was characterized with a fibre analyser with a spatial resolution of approximately 4 μm/pixel and a wide size range. The fines fraction of the refined pulp was also characterized with an imaging flow cytometer with a spatial resolution of 0.33 μm/pixel and a narrower size range. The fibre analyser measurements showed that the mean length, width, and aspect ratio of the fines decreased monotonically with accumulated refining energy. The imaging flow cytometer with its higher spatial resolution showed little change in fines morphology with accumulated refining energy. The morphology of the fines was more dependent on the applied specific refining energy than the design of the refining segment. However, a segment with much finer grooves and bars, initially designed for hardwood, gave significantly less fibre shortening, fines generation, external fibrillation, kink, and fines that were more fibrillar, compared to the other segments.Grant: The authors of this work would like to thank Prof. Lars Mattsson, Thomas Grahn, and Eva Ålander for fruitful discussions. The discussions with Lorentzen & Wettre were of great assistance. The financial support of the Swedish Energy Agency and the Önnesjöstiftelsen to the PhD project, and of the Fibre and Stock Design research programme to this evaluation study is gratefully acknowledged.

  • 61.
    Hyll, Kari
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. King's College London, UK.
    Farahani, Farnaz
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Mattsson, Lars
    KTH Royal Institute of Technology, Sweden.
    Comparison of optical instruments for fines and filler characterisation2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 1, p. 97-109Article in journal (Refereed)
    Abstract [en]

    A laser diffractometer and three image-based instruments with spatial resolutions between 0.33 and 10 µm/pixel were compared through measurements on calibration spheres and fine fractions comprising pulp fines of various types, neat PCC filler, and a mixture of fines and fillers. The laser diffractometer was highly sensitive to the keyed in refractive index of the samples, which was calculated based on volume-based mixing rules. A high-resolution flow cytometer and a high-resolution fibre analyser were found to be complimentary for measurements on neat fines and fines/filler mixtures, and superior to the laser diffractometer. When measuring on fillers, the laser diffractometer performed as well as the high-resolution flow cytometer, which was capable of resolving single filler particles. The sizes of the calibration spheres were overestimated by the image-based instruments, and the measurement uncertainty was high. The uncertainty was mainly attributed to the unrestricted particle motion, and the low accuracy to the dissimilar optical properties of the calibration material, compared to fines. Thus, calibration materials with shape and optical properties more similar to fines should be developed.

  • 62.
    Hyll, Kari
    et al.
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Mattsson, Lars H.
    KTH Royal Institute of Technology, Sweden.
    A method for measurement of the directional emittance of paper in the infrared wavelength range2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 5, p. 958-967Article in journal (Refereed)
    Abstract [en]

    A method for measuring the directional emittance of paper and board samples was developed. The available literature showed that the influence of temperature and observation angle on the emittance of dry and moist paper had not been investigated in detail. Methods adapted for such investigations were not available. In the developed method, the emittance of a sample is determined by comparing its infrared radiation with the radiation emitted from a reference surface with known emittance. In order to investigate the influence of the wavelength range, two cameras, operating in the mid-wavelength and long-wavelength infrared range, respectively, were used. The method allows for the adjustment of the directional emission angle in a range from 0° down to 80°, and variation of the sample temperature between 30°C and 100°C. A study was performed to evaluate the method. Here, the directional emittance of handsheets made from thermo-mechanical pulp was measured at different wavelength ranges, sample temperatures and emission angles. The obtained emittance values and trends were in agreement with previous experimental work and theoretical predictions. The emittance of the samples was also measured using Fourier-Transform Infrared spectroscopy. Given the methodological differences between the two measurement approaches, the results were in good agreement.

  • 63.
    Hyll, Kari
    et al.
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Nygårds, Mikael
    RISE, Innventia.
    Analysis of the plastic and elastic energy during the deformation and rupture of a paper sample using thermography2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 329-334Article in journal (Refereed)
    Abstract [en]

    Thermography has been used to quantitatively analyze the plastic and elastic energy during deformation of paper. Sack paper samples were subjected to uniaxial tensile testing until rupture occurred. The temperature of the sample was simultaneously recorded with an infrared camera. The mechanical energy invested in the deformation was determined based on the force and deformation data. The thermal energy that accumulated in the sample during testing was estimated using the temperature measurements. Here, special attention was put on using the correct emittance values for the sack paper by measuring it with a new method. When comparing exerted mechanical energy with released thermal energy up to the time of sample rupture, about 40% to 60% of the mechanical energy could be detected as thermal energy. The lacking share of heat was most likely lost due to cooling of the sample during the experiments, as a lower share of detected mechanical energy was obtained for longer experiments. When comparing the increase in thermal energy during rupture to the elastic energy stored in the sample, an agreement of better than 90% was found.

  • 64.
    Jacobs, Anna
    et al.
    STFI.
    Dahlman, Olof
    STFI.
    Absolute molar mass of lignins by size exclusion chromatography and MALDI-TOF mass spectroscopy2000In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 15, no 2, p. 120-127Article in journal (Refereed)
  • 65.
    Javed, Asif
    et al.
    Karlstad University, Sweden.
    Rättö, Peter
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging. Karlstad University, Sweden.
    Järnström, Lars
    Karlstad University, Sweden.
    Ullsten, Henrik
    Karlstad University, Sweden.
    Crack analysis of barrier coatings based on starch and starch-PVOH with and without plasticizer2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 2, p. 336-347Article in journal (Refereed)
    Abstract [en]

    Barrier coatings based on starch and starch-PVOH plasticized with glycerol and without plasticizer were applied to two different paperboard substrates, a triple coated board and duplex board, in order to investigate the tendency for cracks to develop in the barrier coating layers during creasing and folding. Tensile properties of films based on the starch and starch-PVOH blend were determined to investigate the relationship between the flexibility of the films and the cracking in the barrier coating layers. Furthermore, the oxygen transmission rate through the barrier-coated paperboard was measured before and after creasing and folding. The oxygen transmission rate through the barrier-coated samples was over the measurable range i. e. OTR > 10000 cm 3 / m 2 day\text{OTR}>10000\hspace{0.1667em}{\text{cm}}^{3}/{\text{m}}^{2}\hspace{0.1667em}\text{day} after creasing and folding, which indicated failure in the barrier coating layers. Optical microscopy revealed small cracks in the barrier coating layers, probably related to an increase in flexibility of the barrier coating layers. It was observed in scanning electron micrographs that cracks in the barrier coating layers seemed to follow the fibers when the barrier coating was applied on the rear side of the duplex board. Scanning electron micrographs and surface profiler images revealed that cracks in the barrier coating layers might have originated from the mineral coating layer when the starch and starch/PVOH coating layers were applied on the mineral-coated side of the triple coated board. An increase in the thickness of the barrier coating layer did not seem to increase the resistance to failure.

  • 66.
    Javed, Asif
    et al.
    Karlstad University, Sweden.
    Ullsten, Henrik
    Karlstad University, Sweden.
    Ernstsson, Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Järnström, Lars
    Karlstad University, Sweden.
    Study of starch and starch-PVOH blends and effects of plasticizers on mechanical and barrier properties of coated paperboard2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 499-510Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of self-supporting films based on starch-plasticizer and starch-PVOH-plasticizer and the barrier properties of paperboard coated with solutions of these polymers have been studied. The plasticizers used were glycerol, polyethylene glycol and citric acid. It was shown that the addition of a plasticizer and PVOH to starch substantially increases the flexibility of starch films. It was seen that curing the self-supporting films led to a decrease in flexibility. After heat-treatment, a substantial increase in storage modulus was observed only in the starch-PVOH-citric-acid blend films. Tensile tests on the films indicate that citric acid did not cause any noticeable phase separation. Citric acid acted as a compatibilizer for starch-PVOH blends even though a similar enrichment of PVOH at the air-solid interface was observed with both citric acid and polyethylene glycol as plasticizer. The properties of barrier coatings greatly reflected the compatibility of starch-PVOH blends containing citric acid. The only plasticizer that resulted in a lower water vapour transmission rate through the starch and starch-PVOH coatings was citric acid, which suggests that cross-linking took place. With four layers, coatings based of starch-PVOH possessed the same oxygen- transmission rate with citric acid as without citric acid.

  • 67.
    Javed, Asif
    et al.
    Karlstad University, Sweden.
    Ullsten, Henrik
    Karlstad University, Sweden.
    Rättö, Peter
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging. Karlstad University, Sweden.
    Järnström, Lars
    Karlstad University, Sweden.
    Lignin-containing coatings for packaging materials2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 3, p. 548-556Article in journal (Refereed)
    Abstract [en]

    The mechanical properties and chemical stability in water of self-supporting films made from aqueous solutions of starch and lignin, and the barrier properties of paperboard coated with solutions of these polymers have been studied. The dissolution of starch from the starch-lignin films in contact with the model liquids was decreased significantly when lignin was added to the starch films. The addition of ammonium zirconium carbonate (AZC) to the formulations as a crosslinking agent substantially increased the storage modulus of the starch-lignin films, which indicated that crosslinking had occurred. The addition of AZC to the formulations also led to a decrease in dissolution of both starch and lignin from the starch-lignin films in contact with model liquids. The effect of AZC on the water stability of the films was greater when the pH of the starch-lignin-AZC solution was adjusted with ammonia rather than NaOH. The addition of NH4Cl solution as a presumed catalyst to the recipe when the pH adjustment was performed with NaOH did not improve the effect of AZC on the water stability of the films. The water vapour transmission rate of the coated paperboard decreased slightly when AZC was added to the coating formulation.

  • 68.
    Joelsson, Tove
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy. Mid Sweden University, Sweden.
    Pettersson, Gunilla
    Mid Sweden University, Sweden.
    Norgren, Sven
    Mid Sweden University, Sweden.
    Svedberg, Anna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Höglund, Hans
    Mid Sweden University, Sweden.
    Engstrand, Per
    Mid Sweden University, Sweden.
    High strength paper from high yield pulps by means of hot-pressing2020In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 35, no 2, p. 195-204Article in journal (Refereed)
    Abstract [en]

    The hypothesis is that it should be possible to modify papermaking conditions in line with the softening properties of high yield pulp fibres and achieve similar strength properties to conventional chemical pulp based paper. We therefore investigated the rheological and physical properties of high yield pulp based papers during hot-pressing. Our results confirm that increased temperature combined with sufficient pressure enables permanent densification by softening of lignin, producing very high tensile strength. This treatment also significantly improved the wet tensile strength in comparison to bleached kraft pulp without using wet strength agents. The high yield pulps used here were spruce based thermomechanical pulp, chemi-thermomechanical pulp, and high temperature chemi-thermomechanical pulp, and birch-aspen based neutral sulphite semi chemical pulp, with spruce-pine based bleached kraft pulp as reference. Rapid Köhten sheets of 150 g/m 2 150\hspace{0.1667em}\text{g}/{\text{m}^{2}} and 50 % dryness were hot-pressed in a cylinder-press at 20-200 °C, 7 MPa, and 1 m/min. The mechanical properties showed great improvements in these high yield pulp papers, with tensile index increased to 75 kNm/kg and compression strength index to 45 kNm/kg; levels close to and better than bleached kraft. Wet strength increased to 16 Nm/g compared to 5 Nm/g for bleached kraft. 

  • 69.
    Johansson, B
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Johansson, M
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Agglomeration of ink particles using a mixture of a fatty acid sodium salt and a non-ionic surfactant2000In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 15, p. 243-250Article in journal (Refereed)
    Abstract [en]

    Studies on a model ink suspension have shown that the effect of non-ionic dispersion agents on ink agglomeration using fatty acid chemistry as collector was highly temperature-dependent. The non-ionic surfactant reduced the agglomeration efficiency at low temperatures (below the cloud point of the surfactant) but this negative effect was reduced at increasing temperatures. At temperatures above the cloud point the non-ionic surfactant improved the agglomeration. The non-ionic surfactant adsorbs to both the ink and precipitated soap particles, which at low temperatures resulted in an increased colloidal stability of the particles but at higher temperatures led to a destabilisation of the particles due to the increased hydrophobicity of the surfactant. The surfactants clearly affected the precipitation of fatty acid anions to calcium soaps and at very high surfactant concentrations the formation of calcium soap particles was drastically reduced. The most favourable conditions seemed to be intermediate surfactant concentrations (0.1 mM). At this concentration the fatty acid was precipitated as small soap particles which, at a temperature above the surfactant cloud point, had good ink agglomeration efficiency. The surfactant improved agglomeration of very small particles, an effect that possibly could be explained by a reduced initial destabilisation rate of the soap particles. A fatty acid collector system produces very fast large aggregates of soap and ink particles, and small residual ink particles cannot easily be incorporated into the large aggregates due to hydrodynamic forces (Johansson et al. 1998). Thus, in a well-balanced system, the non-ionic surfactant may not only facilitate ink detachment and reduce redeposition; it may also promote agglomeration.

  • 70.
    Johansson, B
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Ström, G
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Surface chemistry of flotation deinking: Effect of various chemical conditions on ink agglomerate character and flotability1998In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 13, p. 37-49Article in journal (Refereed)
    Abstract [en]

    Interaction between ink particles and air bubbles has been determined by contact angle and flotation experiments. Different parameters have been tested concerning their effect on these interactions. The contact angles for the ink-soap agglomerates were much lower than expected, which means poor interactions between the solid surface and the air bubble. The angles were in the range between 18° and 63°, indicating an area for improvements. The angle was improved by increased electrolyte concentrations, a hydrophobicing agent (AKD), a non-ionic surfactant, increased amount of calcium soap and strangely enough with CMC. The contact angle has to be more than 50° (Dalmijn 1995) for flotation of large particles while lower contact angles can be accepted when flotating smaller particles, due to hydrodynamical reasons. No correlation between surface tension of the liquid phase and the contact angle was observed. This indicates that the contact angle is mainly determined by the hydrophobic/hydrophilic property of the solid surface. The flotation experiments showed that a high agglomeration efficiency (right size) is more important for the flotation than a high contact angle. Actually all chemicals with dispersion properties i.e. CMC, starch and non-ionic surfactants, decreased the flotation efficiency.

  • 71. Johansson, B
    et al.
    Wickman, M
    Ström, G
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Surface chemistry of flotation deinking: Agglomeration kinetics and agglomerate structure1996In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 11, no 2, p. 74-85Article in journal (Refereed)
    Abstract [en]

    Agglomeration kinetics of dried and aged offset ink particles in the flotation deinking of recycled printed papers has been studied using a photometric dispersion analyser. The model ink particles had a volume mean diameter of 1 µm and calcium oleate was used as collector. The agglomeration speed increased with increasing agitation rate, increasing pH and increasing concentrations of sodium oleate, calcium chloride, sodium chloride, sodium metasilicate or pectic acid. The age of the print, the temperature, the amount of hydrogen peroxide had no or very little influence on agglomeration. The agglomeration decreased with increasing concentrations of non-ionic surfactant, starch or carboxymethylcellulose. Theoretical calculations in a deinking system shows that virtually all sodium oleate forms calcium oleate which precipitates at a pH above 6.5. The pH decreases slightly with increasing calcium concentration. Surface tension measurements in the calcium chloride - sodium oleate system indicate that the precipitation of calcium oleate is a rapid process. The equilibrium between free oleate anions and calcium oleate seems to be reached almost completely after 20 minutes of diffusion-controlled mixing. An analysis of the ink agglomerate structure by determining the boundary fractal dimensions showed that they were built up of smaller agglomerates. Flotation deinking is the most commonly used method for ink removal from waste paper in European paper recycling plants. The waste paper is dispersed in the pulper by mechanical agitation and chemical treatment, after which the ink particles released are separated through flotation. The fundamental chemical stages of ink removal during deinking may be identified as ink detachment, ink particle re-deposition, ink particle agglomeration, attachment of ink agglomerates to air bubbles and flotation. Efficient ink detachment and low re-deposition are of course desired. These processes are believed to be promoted by a high pH which swells the fibre wall and increases the negative surface charge of both fibre and ink. They are also promoted by detergent chemicals such as soaps and synthetic surfactants, which lower the inkwater interfacial tension and improve the colloidal stability of the ink particles. Ink flotation is favoured by large ink particles or ink agglomerates and by a high ink-water interfacial tension i.e. by hydrophobic particles. It is quite obvious that the ink particle properties required to improve ink detachment and decrease re-deposition are undesirable during flotation. In parti cular, this appli es to the ink particle si ze and surface hydrophobicity. Very important sub-processes are thus the surface modification and agglomeration of small ink particles. The understanding of ink particle agglomeration and flotation is limited and various mechanisms have been proposed in the literature (Schweitzer 1965; Bechstein, Unger 1972; Ortner et al. 1975; Ortner 1981; Fischer 1982; Larsson et al 1982, 1984a; Hornfeck 1982; Putz et al. 1991). The aim of our work is to improve the fundamental understanding of these sub-processes through studies in well-defined model systems. In this paper, we concentrate upon ink agglomeration. A number of studies of model systems have been reported (Larsson et al. 1982, 1984a-b; Milanova, Dorris 1993; Dorris, Nguyen 1995, Epple et al. 1994). Larsson et. al. worked with an aqueous dispersion of letterpress ink. Their work suggests that a calcium soap collector acts through the precipitation of small calcium soap particles and co-agglomeration of ink particles and calcium soap particles. Calcium soap particles adsorb onto the ink particles rendering the agglomerate hydrophobic and floatable. Milanova, Dorris and Nguyen have worked with aqueous dispersions of offset lithographic inks and flexographic inks. They found that calcium soaps of fatty acids were effective collectors and flotation agents for flexographic ink. This indicated that problems associated with the deinking of flexographic inks depend on other parameters in the system. Redeposition onto fibres is one possible explanation of the poor deinking ability of flexographic inks (Dorris, Nguyen 1995). Epple, Schmidt and Berg studied the flotation of dispersed xerographic toners. The toner used was not printed before dispersion. Then results showed not only that the type of surfactant was important but also that there was an optimal dosage for each surfactant. Adsorption of anionic, non-ionic and cationic surfactants onto the toner particles all occurred tail-on. To yield practicai information, the basic knowledge derived from model systems should be verified with laboratory and pilot plant trials. Hence, the model system should approach as closely as possible the industrial process. For offset inks, this implies that ink oil should be separated from the pigment and binder, and that oxidation reactions within the binder should have taken place i.e. the ink used for the preparation of an ink suspension should have been applied to a paper, dried and aged. In this paper, we describe a method of preparing such an ink suspension. The ink suspension collected and used in our model experiment has a volume mean particle diameter of 1µm, with all particles less than 8µm, which makes it particularly suitable for agglomeration studies since these small particles have a very low flotation separation efficiency unless they are agglomerated (Larsson et al. 1984b; Marchildon et al. 1989; Saint Amand, Perrin 1991; NauJock et al. 1992). This paper concentrates upon calcium oleate as collector and consists of three parts. The main part deals with agglomeration kinetics. Effect of agitation, pH, process chemicals and substances entering the system with coated papers, e.g. carboxymethylcellulose and starch, is studied. The paper also comments on the equilibrium formation of various chemical species, calcium soap formation and the structure of ink agglomerates as revealed by fractal analysis.

  • 72.
    Johansson, Lars
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, J.
    Gorski, D.
    Axelsson, P.
    Improvement of energy efficiency in TMP refining by selective wood disintegration and targeted application of chemicals2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 31-46Article in journal (Refereed)
  • 73.
    Karlsson, Erik
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy. Chalmers University of Technology, Sweden.
    Åkesjö, Anders
    Chalmers University of Technology, Sweden.
    Sodium salt scaling in black liquor evaporators and the effects of the addition of tall oil brine2020In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, p. 469-480Article in journal (Refereed)
    Abstract [en]

    Sodium salt scaling, i. e. the formation of doubles salts comprised of sodium, carbonate and sulphate on the heat transfer surfaces, is a common problem that occurs during black liquor evaporation. In this study, experimental results are presented that provide new insights into the formation and composition of such scales and how they are influenced by the addition of tall oil brine. It was found that increased content of sodium carbonate and sodium sulphate in the black liquor increased scaling, while the ratio between carbonate and sulphate had a lesser influence than reported in other studies. Black liquor created loose clay-like scales comprised of aggregated crystals and black liquor, whereas salt solutions created hard mineral-like scales. The scales formed by both the black liquor and the salt solution showed a tendency to fall off during formation after primary nucleation. It was also found that both tall oil soap and alkalized tall oil brine could inhibit the formation of scales. The inhibition effect is stronger if adding the soap or brine just before scaling starts, but also depends on the amount added, the sodium carbonate and sodium sulphate content in the liquor as well as other factors.

  • 74.
    Karlström, Anders
    et al.
    Chalmers University of Technology, Sweden.
    Johansson, Lars
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, PFI.
    Hill, Jan
    QualTech, Sweden.
    On the modeling of tensile index from larger data sets2019In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 34, no 3, p. 289-303Article in journal (Refereed)
    Abstract [en]

    The objective of this study is to analyze and foresee potential outliers in pulp and handsheet properties for larger data sets. The method is divided into two parts comprising a generalized Extreme Studentized Deviate (ESD) procedure for laboratory data followed by an analysis of the findings using a multivariable model based on internal variables (i. e. process variables like consistency and fiber residence time inside the refiner) as predictors. The process data used in this has been obtained from CD-82 refiners and from a laboratory test program perspective, the test series were extensive. In the procedure more than 290 samples were analyzed to get a stable outlier detection. Note, this set was obtained from pulp at one specific operating condition. When comparing such "secured data sets" with process data it is shown that an extended procedure must be performed to get data sets which cover different operating points. Here 100 pulp samples at different process conditions were analyzed. It is shown that only about 60 percent of all tensile index measurements were accepted in the procedure which indicates the need to oversample when performing extensive trials to get reliable pulp and handsheet properties in TMP and CTMP processes.

  • 75.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Schack, Susanne
    RISE, Innventia.
    Fasci, Giuseppe Carmini
    RISE, Innventia.
    New insights into retention aids dosage and mixing2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 192-201Article in journal (Refereed)
    Abstract [en]

    In this work, critical design and operational parameters for retention aids dosage are studied through a combination of computational fluid dynamics (CFD), experimentation and pilot-scale production trials. In the first part of this work, three different retention aids dosage strategies are investigated in conjunction with pilot scale production trials. In all dosage strategies, a maximum in the percentage filler retention was observed at a speed ratio of 1.1, while considerably lower retention levels were observed when the speed ratio was greater than 2.2. However, the different dosage strategies led to markedly different retention of filler material. In the second part of this work, two-phase computational fluid dynamics (CFD) was used to model the three different dosage strategies implemented in the pilot production trials. The location and magnitude of maximum strain in each nozzle was determined and for each dosage case this was found to occur just outside the dosage nozzle at the point of impingement between the dosage and outer flows. In the third part of this work, conditions leading to the onset of retention polymer degradation were determined using an experimental flow loop. The effect of dosage speed and elongational strain created inside the dosage nozzle were studied systematically. These experiments showed that the effect of relative dosage velocity on polymer degradation was minimal. However, large levels of polymer degradation were observed when the elongational strain in the dosage nozzle was increased, i.e. when the exit nozzle diameter was decreased. Together, the three sets of experiments suggest that elongational strain during dosage degrades retention aids polymers and therefore hinders filler retention during production.

  • 76. Laine, J
    et al.
    Stenius, P
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Carlsson, G
    Ström, G
    The effect of ECF and TCF bleaching on the surface chemical composition of kraft pulp as determined by ESCA1996In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 11, p. 201-210Article in journal (Refereed)
  • 77.
    Lappalainen, Timo
    et al.
    VTT Technical Research Centre of Finland, Finland.
    Salminen, Kristian
    VTT Technical Research Centre of Finland, Finland.
    Kinnunen, Karita
    VTT Technical Research Centre of Finland, Finland.
    Järvinen, Marjo
    VTT Technical Research Centre of Finland, Finland.
    Mira, Isabel
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Andersson, Martin
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Foam forming revisited. Part II. Effect of surfactant on the properties of foam-formed paper products2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 689-699Article in journal (Refereed)
    Abstract [en]

    This article focuses on the properties of paper samples made using foam-laid technology. The effects of three surfactants, namely sodium dodecyl sulphate (SDS), sodium alkyl ether sulphate (SAES), and linear chain alkyl polyglucoside (C8/C10-Gluc), on properties of foam formed paper samples were studied, using chemithermo-mechanical (CTMP) spruce pulp and bleached kraft pulp. The results show that the type of surfactant used in foam forming has significant effects on the mechanical properties and quality of paper. In the presence of ionic polymers, the charge of surfactant has a significant effect on the formation of the paper sample. It was also shown that at AKD dosages ≥ 3 kg/t, the water absorbency of water formed paper samples was greater than that of foam-formed samples made using C8/C10-Gluc. Foam-forming also produced greater dryness after forming and wet-pressing than the water forming method. The type and dosage of surfactant had a significant impact on dewatering. Filler retention of foam-formed samples was significantly higher when using a non-ionic surfactant instead of an anionic surfactant. The effect of the strength additive (cationic starch) in increasing the strength of foam-formed samples was less in the presence of anionic surfactants than with non-ionic surfactants. 

  • 78. Larsson, A
    et al.
    Stenius, P
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Sorption of small organic molecules by cellulose from hexane solutions1987In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 2, p. 87-91Article in journal (Refereed)
  • 79. Larsson, P. A.
    et al.
    Hoc, Miroslav
    RISE, Innventia.
    Wågberg, L.
    A novel approach to study the hydroexpansion mechanisms of paper using spray technique2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 4, p. 371-380Article in journal (Refereed)
    Abstract [en]

    A new method has been developed to measure the dimensional stability of printing paper by measuring the impact of liquid water on the in-plane dimensional change, i.e. the hydroexpansion, without any simultaneous mechanical interference that can occur when water is pressed into the sheet. This was achieved by using a specially developed spray technique and using electronic speckle photography to continuously measure the dimensional change as water is applied. The in-plane expansion for a given change in moisture content was found to be lower in the case of hydroexpansion than for earlier reported hygroexpansion. After the initial expansion following the water application, it was found that sheets rapidly start to contract again already 10-20 seconds after being wetted, i.e. despite still having a fairly constant and significantly higher moisture content than the initial moisture content before water application. These effects suggest that there are different mechanisms behind hydroexpansion than hygroexpansion of paper, and that hygroexpansion measurements should be extrapolated with caution when evaluating papers with respect to printability.

  • 80. Lindström, M
    et al.
    Ödberg, L
    Stenius, P
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Resin and fatty acids in kraft pulp washing. Physical state, colloid stability and washability1988In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 3, p. 100-106Article in journal (Refereed)
  • 81.
    Lindström, Tom
    et al.
    RISE, Innventia.
    Fellers, Christer
    RISE, Innventia.
    Ankerfors, Mikael
    BillerudKorsnäs AB, Sweden.
    Glad Nordmark, Gunborg
    RISE, Innventia.
    On the nature of joint strength of paper: Effect of dry strength agents - Revisiting the Page equation2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 459-468Article in journal (Refereed)
    Abstract [en]

    This report deals with the effects of various chemical-treatments - carboxymethylcellulose-grafted (CMC) pulp in different ionic forms (Na+, Ca2+, and Al3+), cationic starch, anionic polyacrylamide, and microfibrillated cellulose (MFC) as well as PFI-refining on the strength properties of never-dried bleached soft-wood kraft pulp. The general in-plane strength properties were measured together with z-strength and interlaminar shear strength. The sheet density was varied by pressing the wet sheets to various dry solids content. The relative bonded area of the sheets was determined by the BET surface area of the sheets using krypton adsorption. Interlaminar shear strength is introduced as a measure for fibre-fibre bond strength and validates its use in the Page equation from first principles and it was shown to hold over a large range of tensile strengths. Only at very high tensile index values the calculated tensile index deviated from measured tensile index. This was most likely due to a shift from adhesive to cohesive failure of the joint. The various strength reinforcement methods used were all based on carbohydrate based additives and for those additives the specific joint strength was found to be independent of the specific additive, so the strength reinforcement is only related to the increased relative bonded area upon the addition of the strength adjuvant, although the additives consolidate the sheet on various structural levels.

  • 82.
    Lindström, Tom
    et al.
    RISE, STFI-Packforsk.
    Larsson, Per Tomas
    RISE, STFI-Packforsk.
    Alkyl ketene dimer (AKD) sizing: A review2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 2, p. 202-209Article in journal (Refereed)
    Abstract [en]

    Over the years, there have been great efforts to try to develop cellulose reactive sizing agents. The assumption in these developments have been that the covalent linkage allows permanent attachment of hydrophobic groups in a highly oriented state, which makes sizing possible at very low levels of added chemical. The main requirement of the molecule is that it should have a balance between the reactivity towards water, because of the necessity of making stable emulsions or dispersions, and its reactivity towards cellulose. These assumptions are to some extent mutually exclusive and a compromise must be sought. Although, many different types have been tried out over the years the most important sizes used are the Alkyl Ketene Dimers (AKD) and the Alkenyl Succinic Anhydrides (ASA). These sizing agents are at the opposite in terms of stability of hydrolysis and reactivity towards cellulose, where AKDs are the least reactive species and fairly stable towards hydrolysis, whereas ASAs are very reactive towards cellulose, but also sensitive to hydrolysis. The mechanism of action is fairly well known for AKD, but less known for ASA and AKD-sizing can be regarded as a pretty mature field from a scientific point of view. The aim of this contribution is to summarize the fundamental features of AKD-sizing and discuss and highlight the most important aspects for the practical papermaker. Over the years there have been many reviews (e.g. (Dumas 1975; Reynolds 1989; Eklund and Lindström 1991; Hodgson 1994; Roberts 1997; Hubbe 2006)) in the field of AKD-sizing, but there have been extensive recent research activities over the past 10 years and there is a need for a comprehension of these research activities.

  • 83.
    Lindström, Tom S. C.
    et al.
    RISE Research Institutes of Sweden. KTH Royal Institute of Technology, Sweden.
    Glad-Nordmark, Gunborg
    RISE Research Institutes of Sweden.
    Novel bulking technologies for cellulose fibres2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 1, p. 25-41Article in journal (Refereed)
    Abstract [en]

    This paper deals with the details of preparation of three principal routes for bulking of cellulose fibres. One route is dry cross-linking/hornification using aluminium ions and other salts followed by drying/curing. The mechanisms of these reactions still remain unknown. A second route is physical grafting of fibres using carboxymethylcellulose and bringing the acidic groups into their aluminium form before forming a sheet of paper/board. Hence, curing is not necessary, and this constitutes a unique wet bulking methodology. The mechanism behind this method is believed to be an increase in the surface friction of fibres, when the electrostatic double layer is shielded together with electrostatic cross-linking with aluminium ions. The higher friction between fibres partly prevents the sheet consolidation during drying. A third route is physical grafting of fibres using carboxymethyl cellulose and ion-exchanging the acidic groups with aluminium salts before drying and curing of the fibres. A most interesting factor is that all the thermal treatment methods do not form fibre nodules due to interfibre crosslinking during the heat treatment, a commonly observed phenomena when dealing with chemical crosslinking of fibres. All routes investigated are water-based and should be fairly simple to implement in commercial operations. An inherent advantage is that the bulking is associated with lower water retention values, which should be advantageous for a higher solids content after pressing and, hence, beneficial for paper machine productivity. Bulking is, however, also associated with a loss in bond strength, which in most cases must be alleviated using various additives such as starches and microfibrillated cellulose and it has also been demonstrated in the project how the strength properties (such as z-strength) could be restored at a higher bulk.

  • 84.
    Lindström, Tom S. C.
    et al.
    RISE Research Institutes of Sweden. KTH Royal Institute of Technology, sweden.
    Ström, Göran
    RISE Research Institutes of Sweden.
    Bulking of cellulose fibres - A review2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 1, p. 192-204Article, review/survey (Other academic)
    Abstract [en]

    This paper summarizes chemical technologies aimed at making bulking fibres, a technology mainly practiced in the area of tissue and hygiene products but also highly relevant for board products made by sheet stratification containing bulking layers in the middle of the board in order to improve the bending stiffness of the board. There is a long history of different ways to make bulking fibres albeit the fact that such technologies have scarcely been used for commercial stratified board (apart from a variety of different pulp types), but more in tissue and hygiene products. The objective is to review the very different approaches that may be used for the purpose of making bulking fibres.

  • 85.
    Lucisano, Marco F. C.
    et al.
    RISE, Innventia.
    Martinez, D. M.
    On the characterization of the delamination process during impulse pressing2001In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 16, no 4, p. 362-368Article in journal (Refereed)
    Abstract [en]

    This investigation evaluates the changes in web structure of impulse pressed paper webs. 60 g/m2 wet paper webs made from two stock types (SBK and a 60:40 mixture of SBK with HT-CTMP) were pressed either on laboratory scale or on a research paper machine. The pressing temperature was increased stepwise from 40°C to 290°C. The sampled wet paper webs were either dried in restraint in an oven, freeze-dried, or stored in sealed plastic bags at 4°C. Paper samples were obtained both before and after the pressing event, and the evolution of the cross-sectional solidity profile and transverse permeability was measured as a function of pressing temperature. Delamination was first observed at a pressing temperature of approximately 230°C. For non-delaminated paper webs, the cross-sectional solidity profiles translated uniformly towards higher solidities with increasing pressing temperature. We found no evidence of stratification. For delaminated sheets, however, large fractures were evident, with the damage plane located approximately 1/3 of the way in the total basis weight of the sheet, measured away from the hot surface. The permeability of unloaded samples decreased monotonically with increasing pressing temperature reflecting the fact that the paper samples densified by reduction of the external pore size. The permeability of mechanically compressed, never-dried samples was found to be essentially constant for non-delaminated sheets and to increase significantly for samples which were delaminated. We propose that this phenomenon could be a result of cell wall damage incurred during the delamination process.

  • 86.
    Lucisano, Marco F. C.
    et al.
    RISE, Innventia.
    Mazzatorta, P.
    Martinez, D. M.
    On the mechanism of steam forming during impulse pressing of wet paper webs2001In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 16, no 4, p. 355-361Article in journal (Refereed)
    Abstract [en]

    Steam forming processes in wet paper webs under-going impulse pressing are characterized here in two different, yet complementary studies. In the first study, we measured the transient temperature profiles of wet paper webs undergoing compression at a constant rate in a heated platen press. Eight micro-thermocouples were embedded into 500 g/m2 SBK wet paper webs at different elevations. The experimental conditions were such that the length of the pressure pulse was varied from 100 ms to 15 s, the initial temperature of the platen press was set from 150°C to 300°C, and the initial dryness of the paper webs were held constant at approximately 30%; approximately 600 experiments were conducted. In the second study, we visualized the flashing event using a novel experimental device. In this part of the work, a 10 cm bed of SBK fibres, with an initial dryness of 40%, was pressurized to approximately 5 bar and heated to 170°C. The hydraulic pressure was then released rapidly causing the water to flash inside the fibre network. The flashing event was recorded by high-speed video and the temperature profile was measured dynamically using fast response thermocouples. The results indicate that steam was formed during the compression phase of the pressure pulse only with long compression times, i.e. t>1 s. In this regime, we found evidence of a heat pipe. Indeed, we found no evidence of a heat pipe with shorter compression times, i.e. t<500 ms. We also observed a sudden increase in temperature in the middle of the paper sample at the end of the pressure pulse and attributed this to flashing. We speculated that the expanding steam displaced the unbound water and allowed heat to be convectively transferred from the top of the sheet to its lower portions. This mechanism was confirmed in the subsequent study in the flashing apparatus.

  • 87. Lundberg, A.
    et al.
    Ortegren, J.
    Alfthan, E.
    Ström, G.
    RISE, Innventia.
    Microscale droplet absorption into paper for inkjet printing2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 1, p. 142-150Article in journal (Refereed)
  • 88.
    Lundström-Hämälä, Lisa
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Processum.
    Lindgren, Johan
    Svensson-Rundlöf, Eva
    Sennerfors, Therese
    Wågberg, Lars
    The adsorption of polyelectrolyte multilayers (PEM) of starch on mechanical pulps for improved mechanical paper properties2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 4, p. 459-468Article in journal (Refereed)
    Abstract [en]

    In the present work, the long fibre and middle fibre fraction of a thermomechanical pulp (TMP) was treated with polyelectrolyte multilayers (PEMs) of cationic and anionic starch and sheets were made from both the treated and untreated fractions. In separate experiments, different amounts of untreated fines were added to the PEM-treated fraction before sheets were prepared, and the results were also compared with PEM treatment of the entire pulp containing 17% fines before sheet preparation. The PEMs were made of two different combinations of starch, two cationic potato starches with DS values of 0.06 and 0.09, both in combination with an anionic potato starch with a DS of 0.04, at 0.010 M NaCl and pH 6.3. Sheets were formed using the Rapid Köthen sheet former and the resulting mechanical and optical sheet properties were evaluated. Four-layer PEM treatment of the long fibre and middle fraction resulted in significant improvements in in-plane and out-of-plane mechanical properties. However, a subsequent fines addition reduced the effect of the PEMs, and this is explained by a blocking of the necessary PEM interaction with the treated TMP long fibre and middle fraction by the subsequently added fines. PEM treatment of the entire pulp increased the amount of starch needed for PEM treatment, but improved the in-plane and out-of-plane mechanical properties compared with those of sheets prepared from a PEM-treated long fibre and middle fraction with a subsequent addition of fine material. The increase in the tensile index for sheets made from a PEMtreated long fibre and the middle fraction without a subsequent fines addition, however, was much larger.

  • 89.
    Magnusson, Mikael
    RISE, Innventia.
    Investigation of interfibre joint failure and how to tailor their properties for paper strength2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 1, p. 109-122Article in journal (Refereed)
    Abstract [en]

    The key property for the load carrying capacity of paper materials is the interfibre joint strength. Due to the difficulty of testing the strength of such microscopic entities, the typical approach is to test isolated fibre-fibre crosses. In such experiments the joint is but one component of the tested structure and the flexural compliance of the long fibre segments results in a mixed mode of loading. Furthermore, the details of the failure mechanisms of such joints are as of yet unknown. A continuum description of the paper sheet is often insufficient to explain governing mechanisms when properties of the underlying structure are changed by mechanical or chemical modifications. Therefore network models are often used to take into account the underlying mechanisms. However, network models in turn rely on the properties of the fibres and of the interfibre joints. This paper aims to characterize the damage behaviour of isolated fibre-fibre crosses from three approaches: identifying typical damage features from an extensive number of mechanical tests of isolated fibre-fibre crosses; study the applicability of using cohesive zones to model the failure behaviour of inter-fibre joints; and, to study the influence of fibre and joint properties to the load carrying capacity of fibre-fibre crosses. The results indicate that the strength in the normal direction is significantly lower than in the shear direction and means on how to tailor the properties of fibres and joints for increasing the load carrying capacity is suggested.

  • 90.
    Marais, Andrew
    et al.
    KTH Royal Institute of Technology, Sweden.
    Enarsson, Lars-Erik
    SCA R&D Centre, Sweden.
    Pettersson, Gunilla
    Mid Sweden University, Sweden.
    Lindström, Tom
    RISE, Innventia.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Pilot-scale papermaking using Layer-by-Layer treated fibres: Comparison between the effects of beating and of sequential addition of polymeric additives2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 2, p. 308-314Article in journal (Refereed)
    Abstract [en]

    The Layer-by-Layer (LbL) deposition technique was used to treat fibres before papermaking on a pilot scale. Following a laboratory pre-study performed earlier to determine the adsorption isotherms and the kinetics of formation of multilayers of polyamideamine epichlorydrine (PAE) and carboxymethylated cellulose (CMC) on unbeaten, bleached softwood fibres, online LbL treatment of the furnish was carried out on the EuroFEX pilot paper machine. Papers from fibres coated with up to four layers of polyelectrolytes were produced. Two different LbL systems were investigated, with anionic CMC in combination with either PAE or cationic starch (CS). The results showed that the mechanical strength of the paper significantly increased when the fibres were LbL-treated online. A comparison with conventional beating of the fibres revealed that the LbL treatment was a potential substitute to beating treatment, as the density of the LbL-treated papers remained constant while the mechanical properties were significantly improved. At the same time, the press solids content was significantly higher (2%) when using LbL-treated fibres than with beaten fibres.

  • 91.
    Marin, Gustav
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Nygårds, Mikael
    RISE Research Institutes of Sweden.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Elastic-plastic model for the mechanical properties of paperboard as a function of moisture2020In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 35, no 3, p. 353-361Article in journal (Refereed)
    Abstract [en]

    To verify a linear relation between normalized mechanical property and moisture ratio, in-plane tensile tests were performed on four types of paperboard from different manufacturers. Tensile properties were normalized with respect to the property at standard climate (50 % RH, 23 °C). Short-span Compression Tests were also performed to investigate if the relation was linear also for in-plane compression. The tests were performed at different relative humidity (20, 50, 70 and 90 % RH) but with constant temperature (23 °C) in MD and CD, respectively. The linear relation was confirmed for the normalized mechanical properties investigated. In fact, when also the moisture ratio was normalized with the standard climate, all paperboards coincided along the same line. Therefore, each mechanical property could be expressed as a linear function of moisture ratio and two parameters. Moreover, an in-plane bilinear elastic-plastic material model was suggested, based on four parameters: Strength, stiffness, yield strength and hardening modulus, where all parameters could be expressed as linear functions of moisture ratio. The model could predict the elastic-plastic behavior for any moisture content from the two parameters in the linear relations and the mechanical properties at standard climate.

  • 92.
    Mira, Isabel C.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Andersson, Martin P.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Boge, Lukas
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Blute, Irena A.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Carlsson, Gilbert
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Salminen, Kristian
    VTT Technical Research Centre of Finland, Finland.
    Lappalainen, Timo
    VTT Technical Research Centre of Finland, Finland.
    Kinnunen, Karita
    VTT Technical Research Centre of Finland, Finland.
    Foam forming revisited Part I. Foaming behaviour of fibre-surfactant systems2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 679-688Article in journal (Refereed)
    Abstract [en]

    The foaming properties of typical chemithermo-mechanical (CTMP) and kraft pulp paper making formulations in the presence of a series of surfactants were investigated using a lab-scale foaming set up. Foamability, foam stability, and bubble size distribution of the generated foam-fibre systems were measured. The foaming behaviour of the fibre/surfactant systems was found to be dependent on the surfactant concentration. Foams fulfilling the target requirements of air content (ca. 65% v/v air) and average bubble size (25 to 75 μm in radius) were obtained with all the seven surfactants tested. Three of the surfactants were found to allow for a rapid foaming in the system, namely sodium dodecyl sulphate (SDS), a commercial mixture of alkyl and ethoxylated alkyl sulphates, (MixSAES) and a commercial mixture of short chain alkyl glucosides (C8/C10Gluc). The rapid foaming is believed to be an intrinsic property of mixtures of surfactants with the right molecular structures and in the right proportion with respect to each other. On the other hand, the minimum surfactant concentrations required to reach the target foam volumes were lowest for surfactants with an anionic character. Further, the type of pulp fibre and the presence of GCC in the surfactant/pulp formulation were found to have very little effect on the foaming performance of the suspensions.

  • 93.
    Mäkelä, Petri
    et al.
    Tetra Pak Packaging Solutions AB, Sweden.
    Fellers, Christer N.
    RISE, Innventia.
    An analytic procedure for determination of fracture toughness of paper materials2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 2, p. 352-360Article in journal (Refereed)
    Abstract [en]

    The aim of the present work was to develop an analytic procedure for determination of the fracture toughness of paper materials based on laboratory material test data. Isotropic deformation theory of plasticity was used to model the tensile material behaviour of six different commercial paper grades. Closed-form analytic expressions for calibrating the material model based on tensile test data were developed. The analytically calibrated material model was shown to predict the non-linear tensile stress-strain behaviour of the investigated paper grades excellently. A closed-form analytic expression for determination of fracture toughness was developed based on the used material model and -integral theory. The fracture toughness of the investigated paper grades was determined analytically based on laboratory fracture toughness test data. The suggested analytic procedure for determination of the fracture toughness was shown to be in excellent agreement with determinations of fracture toughness based on finite element analysis.

  • 94.
    Mäkelä, Petri
    et al.
    RISE, Innventia.
    Nordhagen, H.
    Gregersen, Ø.˜W.
    Validation of isotropic deformation theory of plasticity for fracture mechanics analysis of paper materials2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 4, p. 388-394Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to validate that isotropic deformation theory of plasticity is a suitable material modelling level for fracture mechanics analysis of paper materials, as has been indicated in previous studies. Six different commercial paper grades were investigated. Laboratory material testing was performed for each paper grade using standardised tensile and fracture toughness test methods. The material data was used to calibrate a fracture mechanics model based on isotropic deformation theory of plasticity with a fracture criterion based on the/-integral. The fracture mechanics model was used to predict failures of notched paper webs and corresponding experiments were performed. The experiments and predictions of failures were performed for several different notch lengths for all six studied paper materials. The experimentally determined force and elongation at break of the notched paper webs were predicted excellently by the fracture mechanics model, which shows that isotropic deformation theory of plasticity is a suitable material modelling level for fracture mechanics analysis of paper materials.

  • 95.
    Mörseburg, Kathrin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, Jan
    QualTech AB, Sweden.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    ATMP refining of Norway spruce - Defibration characteristics and fibre wall properties2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 386-400Article in journal (Refereed)
    Abstract [en]

    Defibration and fibre development patterns were investigated for the novel ATMP refining process, based on pilot scale trials with Norway spruce chips. ATMP refining with different chemical agents was compared to RTS refining with and without Impressa-finer (RT) and Fiberizer (F) pre-treatment. RT-F pre-treatment significantly improved both initial defibration, axial fibre splitting and fibre flexibility, compared to RTS primary stage refining without pre-treatment. Both types of investigated ATMP process chemistry - hydrogen peroxide combined with magnesium hydroxide under alkaline conditions (P) or acid sodium bisulphite (S) added to the primary refiner dilution water - further improved the fibre separation of RT-F pre-treated wood during primary stage RTS refining. This is largely attributed to enhanced fibre swelling. S-treatment facilitated frequent fibre separation within or close to the S2 wall layer, yielding extremely low shive levels and well-fibrillated, thin-walled fibres early in the process. S-treatment also rendered stiffer fibres, which made them susceptible to breakage, axial splitting and internal delamination. P-application is proposed to affect primarily the interior layers of the fibre walls, facilitating rapid fibre wall swelling towards the lumen, fibre softening and flexibilization.

  • 96.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Sundström, Jonas
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Enhancing the properties of carboxymethylated nanofibrillated cellulose by inclusion of water in the pre-treatment process2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 372-378Article in journal (Refereed)
    Abstract [en]

    Well-delaminated carboxymethylated nanofibrillated cellulose (NFCCarb) systems are prerequisites for many industrial applications. In this study it was shown that addition of water, in a narrow range, not only improves the efficiency of the carboxymethylation process, but also enhances the degree of delamination of NFCCarb, which leads to improved properties. The observations were proposed to be due to a more homogeneous distribution of the charged groups, brought about by the higher swelling of fibers with inclusion of water.

  • 97.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    A comparative study of the rheological properties of three different nanofibrillated cellulose systems2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 354-363Article in journal (Refereed)
    Abstract [en]

    The rheological properties of NFC systems in different conditions are of important for their handling and implementation in various industrial applications. In this investigation, the existence of wall-slip effects and the rheological characteristics of three different nano-fibrillated cellulose (NFC) systems - enzymatically pre-treated (NFCEnz), carboxymethyl cellulose grafted (NFCCMC) and carboxymethylated (NFCCarb) - were investigated. It was found that the rheological properties of NFCCarb are less affected by wall-slip effects when geometries with serrated surfaces are employed. The other systems showed, however, different degrees of susceptibility to these effects. The thixotropic properties of the different NFC systems, together with the impact of ambient ionic strength and temperature on the rheological properties of the systems, were also studied. It was found that the different systems displayed different rheological behaviours. In short, all systems regained most of their original properties as soon as severe shearing was ceased. The apparent viscosities of NFCEnz and NFCCMC were found to be little affected by the ionic strength of the system. However, the viscosity of the systems decreased somewhat with increasing temperatures. The viscosity of NFCCarb decreased on the other hand with the increasing ionic strength, but otherwise showed little sensitivity towards the ambient temperature. Hence, it was concluded that the rheological properties of NFCCarb were primarily governed by the electrosteric interactions between the NFC entities rather than the viscous properties of the liquid phase.

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  • 98.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Sundström, Jonas
    RISE, Innventia.
    Flodberg, Göran
    RISE, Innventia.
    A comparative study of the properties of three nano-fibrillated cellulose systems that have been produced at about the same energy consumption levels in the mechanical delamination step2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 364-371Article in journal (Refereed)
    Abstract [en]

    The viscosity, tensile strength- and barrier properties of enzymatically pre-treated- (NFCEnz), carboxymethylated- (NFCCarb) and carboxymethyl cellulose (CMC) modified (NFCCMC) nanofibrillated cellulose systems (NFC) that have been produced at about the same energy consumption levels in the mechanical delamination step in the manufacturing of the different NFCs are reported. It was found that NFCEnz and NFCCMC are characterized by low degrees of fibrillation. Carboxymethylated NFC displayed superior tensile strength properties, lower fiber fragment content and a higher viscosity when compared to NFCEnz and NFCCMC. Interestingly, NFCEnz displayed equal or better barrier properties compared to the highly fibrillated NFCCarb.

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  • 99.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Sundström, Jonas
    RISE, Innventia.
    Flodberg, Göran
    RISE, Innventia.
    Can redispersible low-charged nanofibrillated cellulose be produced by the addition of carboxymethyl cellulose?2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 4, p. 568-577Article in journal (Refereed)
    Abstract [en]

    Carboxymethyl cellulose (CMC) was added in various amounts (< 10% (w/w)) to a lowcharged (enzymatically pre-treated) NFC, and the suspensions were blended by either a low-shear propeller mixing- or high shear homogenization protocol. The suspensions were thereafter oven-dried, and redispersed using a high shear protocol. It was found that the mixing method has a profound effect on the apparent rheology of the never-dried systems. The addition of highly charged CMC-grades enabled, already at 1% (w/w) addition, the apparent dispersion of dried NFC. The rheological responses (viscosity and storage modulus) of the neverdried NFC-CMC systems were judged as conserved, when the rheological responses of the redispersed systems were compared with those of never-dried systems that had been produced by propeller mixing. The rheological responses of the redispersed systems were on the other hand found to be lower when compared to the rheological responses of the never-dried systems that had been produced by high shearing mixing. However, the mechanical- and barrier properties of the redispersed systems were found to be inferior to the never-dried equivalents - regardless of the mixing protocol.

  • 100.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Weise, Christoph F.
    NMRArc, Sweden.
    Flodberg, Göran
    RISE, Innventia.
    Sundström, Jonas
    RISE, Innventia.
    Junel, Kristina
    RISE, Innventia. RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Runebjörk, Ann-Marie
    RISE, Innventia.
    Phosphorylated nanofibrillated cellulose: Production and properties2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 1, p. 20-29Article in journal (Refereed)
    Abstract [en]

    Phosphate functionalized nanofibrillated cellulose (NFC) was produced through an industrially attractive process, by reacting wood pulp with a phosphate containing salt, followed by mechanical delamination through microfluidization. The degrees of delamination of the phosphorylated NFCs (judged by among others AFM-imaging, rheological studies and tensile strength measurements on NFC films) were found to improve with increasing functionalization of the pulp and number of microfluidization-passes. The NFC systems were found to display similar characteristics as other well-known NFC systems. Interestingly, however, the sufficiently delaminated phosphorylated NFCs exhibited significantly lower oxygen permeability values (at RH 50%) than the published values of several well-known highly delaminated NFC systems. The potential application of the phosphorylated NFC in packaging applications can hence be envisaged.

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