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  • 1.
    Aldaeus, Fredrik
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Olsson, Anne-Mari
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Miniaturized determination of ash content in kraft lignin samples using oxidative thermogravimetric analysis2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 2, p. 280-282Article in journal (Refereed)
    Abstract [en]

    A study has been made of several aspects of determination of ash content in kraft lignin samples using thermogravimetric analysis (TGA). Three different methods were used; with the main differences between the methods being that two have a temperature hold at 250 deg C to remove volatiles and that the three methods use different maximum temperatures, namely 525, 550 and 575 deg C, respectively. The three kraft lignins used were produced using the LignoBoost lignin isolation process. It has been demonstrated that the results obtained by the different temperature programmes showed no significant difference. The results were comparable with those from using oven ignition. Moreover, the limit of quantification was several orders of magnitude lower than when using oven ignition. It has been recommended that if TGA is used for determination of ash content, a temperature programme from a standard method should be used, which should be mentioned together with the results. The temperature programme in method one (corresponding to ISO 1762) was the shortest and the preferable method. A well as requiring less labour due to fewer movements in the analytical protocol, the TGA methods enabled a high sample throughput due to autosampling possibilities.

  • 2.
    Alfthan, Johan
    RISE, Innventia.
    Experimental study of non-linear stress relaxation and creep of paper materials and the relation between the two types of experiments2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 3, p. 351-357Article in journal (Refereed)
    Abstract [en]

    The non-linear time-dependent mechanical behaviour of three different commercial paper grades was investigated. Stress relaxation and creep tests were carried out in MD and CD using different load levels. The strain in each test was split in a linear part and a non-linear part. From the stress and the linear part of the strain in the test, a stress relaxation modulus or a creep compliance was calculated. The stress relaxation moduli and creep compliances determined in this way were observed to be independent of the load level. The stress relaxation moduli and creep compliances for each paper were further independent of the loading direction (MD/CD) when scaled by the elastic modulus. It was also shown that the stress relaxation modulus was approximately equal to the inverse of the creep compliance, which is what would have been expected if linear viscoelastic theory had been applicable.

  • 3.
    Alm, H.K.
    et al.
    RISE, Innventia.
    Ström, Göran
    RISE, Innventia.
    Karlström, Katarina
    Schoelkopf, J.
    Gane, P.A.C.
    Effect of excess dispersant on surface properties and liquid interactions on calcium carbonate containing coatings2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 1, p. 82-92Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to identify what effects excess amount of sodium polyacrylate, a commonly used dispersant, has on the coating properties and the interaction between ink and the paper coating in offset printing. Since polyacrylate strongly interacts with calcium ions, soluble calcium salt was added to some coating colours to illustrate the impact of charge neutralization by calcium ions. It was found that the coating structure was only slightly affected by the extra addition of polyacrylate, showing some weak flocculation, whereas the surface chemistry was strongly influenced. The coatings became more polar and interacted more strongly with water. This resulted in slower ink setting and reduced ink-paper coating adhesion, especially in the presence of applied water/dampening solution, which are identified as contributory factors in ink piling and print mottle.

  • 4. Andersson, C.
    et al.
    Fellers, C.
    RISE, Innventia.
    Evaluation of the stress-strain properties in the thickness direction: Particularly for thin and strong papers2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 2, p. 287-294Article in journal (Refereed)
  • 5.
    Ankerfors, M.
    et al.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Soderberg, D.
    RISE, Innventia.
    The use of microfibrillated cellulose in fine paper manufacturing: Results from a pilot scale papermaking trial2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 3, p. 476-483Article in journal (Refereed)
  • 6. Ankerfors, Mikael
    et al.
    Lindström, Tom
    RISE, Innventia.
    Glad Nordmark, Gunborg
    RISE, Innventia.
    Multilayer assembly onto pulp fibres using oppositely charged microfibrillated celluloses, starches, and wetstrength resins’ Effect on mechanical properties of CTMP-sheets2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 1, p. 135-141Article in journal (Refereed)
    Abstract [en]

    The effects of multilayering of microfibrillar cellulose (MFC) onto a chemi-thermomechanical pulp (CTMP), from which the fines material had been removed, were investigated with regard to the mechanical properties of hand-sheets. In one series of experiments, the CTMP was multilayered with cationic MFC/anionic MFC (C-MFC/A-MFC) at various addition levels and sheets made in a conventional sheet former, pressed, and dried at room temperature. This experimental series was complemented with a second series, where sheets were made in a Rapid Köthen sheet former. In a third series of experiments, the CTMP was multilayered using a cationic polyamideamine epichlorohydrine resin (PAE) and an AMFC. Sheets were formed using the Rapid Köthen sheet former. Finally, in a fourth series of experiments, the MFC multilayering experiments were compared with multilayering experiments using cationic starch/anionic starch (C-starch/A-Starch). MFC-multilayering (C-MFC/A-MFC) gave inferior strength gain at a low addition level compared to starch multilayering, but (compared on a weight basis) the strength seemed to level off using starches at high addition levels, whereas there were a continuous increase in strength using MFC multilayering. Multilayering using PAE/A-MFC was found to give a higher strength gain than both C-MFC/A-MFC and C-starch/A-starch multilayering. Sheet density was slightly affected (<14%) by the multilayering techniques used in these experiments.

  • 7.
    Ankerfors, Mikael
    et al.
    ÅF Industry, Sweden.
    Lindström, Tom
    RISE - Research Institutes of Sweden, Bioeconomy.
    Glad Nordmark, Gunborg
    RISE - Research Institutes of Sweden, Bioeconomy.
    The effects of different types of wet-end added microfibrillated celluloses on the properties of paper made from bleached kraft pulp2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 3, p. 336-345Article in journal (Refereed)
    Abstract [en]

    Research has been undertaken to compare the effects of different types of microfibrillated cellulose (MFC) on the mechanical properties of paper. Three types of MFC were produced: Enzyme MFC (low anionic charge density), Carboxymethylated MFC (high anionic charge density) and cationic MFC (high cationic charge density). The different MFCs required different retention aid strategies. The simplest retention strategy was selected to secure a high retention of MFC. Some experiments also focused on dewatering and pressability of wet webs with carboxymethylated MFC. Conventional isotropic laboratory handsheets were made using a never-dried unrefined elemental chlorine free (ECF)-bleached softwood kraft pulp. It has been shown that the evolution of the mechanical properties and scattering coefficients when plotted versus MFC content was very similar for the three types. However, Enzyme MFC gave a significantly better reinforcement effect. All three types of MFC had a similar effect on the sheet consolidation, reflected in sheet density. Evaluation of the dewatering and pressability of the wet sheets showed that if the MFC was aggregated by an appropriate retention strategy, the dewatering and pressability were not detrimental to the practical applicability of MFC.

  • 8. Antonsson, S.
    et al.
    Mäkelä, Petri
    RISE, Innventia.
    Fellers, Christer
    RISE, Innventia.
    Lindström, M. E.
    Comparison of the physical properties of hardwood and softwood pulps2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 4, p. 409-414Article in journal (Refereed)
    Abstract [en]

    High mechano-sorptive creep resistance, i.e., good creep resistance in environments with changing relative humidity, is one of the key requirements for linerboards. The aim of this study was to investigate the influence of pulp types and pulp properties on the mechano-sorptive creep of kraftliner. A high-yield softwood, kraftliner pulp, and four different hardwood pulps were investigated. The physical properties of laboratory sheets were evaluated, with emphasis on the mechanosorptive creep properties. The results showed that the density increase due to increased beating significantly improved the tensile stiffness of all pulps, while its effect on the isocyclic creep stiffness was less pronounced. The hardwood pulps showed higher tensile stiffness, better mechano-sorptive creep properties, and lower hygroexpansion than the softwood pulp at a given density. However, the softwood pulp did exhibit better tensile strength and fracture toughness properties than the hardwood pulps. The results imply that hardwood pulps can be competitive with softwood pulps in kraftliners, provided that their tensile strength and fracture toughness properties can be improved by, for example, chemical means. Furthermore, the isocyclic creep stiffness correlates with the ratio of tensile stiffness to hygroexpansion, indicating that this ratio can be used for engineering estimates of the mechano-sorptive creep performance of paper materials.

  • 9.
    Athley, K.
    et al.
    RISE, Innventia.
    Granlöf, L.
    RISE, Innventia.
    Söderberg, D.
    RISE, Innventia.
    Ankerfors, M.
    RISE, Innventia.
    Ström, G.
    RISE, Innventia.
    Mechanical retention - Influence of filler floc size and grammage of the fibre web2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 2, p. 202-207Article in journal (Refereed)
  • 10. Back, EL
    et al.
    Laudi, B
    Elftonson, J
    YKI – Ytkemiska institutet.
    Effect of modifiers on wax properties and on dispersibility under hot alkaline conditions1995In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 10, p. 122-128Article in journal (Refereed)
    Abstract [en]

    This paper is one in a series of papers presenting a process for the removal of modified waxes from old corrugated containers by washing after alkaline hot dispersion of the recycled pulp. It presents experiments for selection of the most useful dispersants to be incorporated as wax modifiers already before the wax application. Criteria for selection were their effect on wax properties such as water and moisture resistance and their efficiency for dispersion to minimum size under hot alkaline conditions. The dispersants must also permit simple coagulation of the wax dispersion for its removal from a closed white water system. The dispersion experiments were carried out on a laboratory scale in the absence of fibers at 90°C and pH 9 to 11. Evaluated was the turbidity both at that temperature and after cooling to 20°C. For the final selection, the particle size distribution at 20°C was also measured. A few per cent of a commercial stearic acid with a minor addition of a nonionic fatty alcohol ethoxylate formula R-O-(CH2)2-O-]nH, was found to be a most suitable and economic wax additive.

  • 11.
    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.

  • 12. Brodin, F.W.
    et al.
    Sonavane, Y.
    Sedin, M.
    RISE, Innventia.
    Displacement washing of TEMPO-oxidized softwood kraft pulp:: Effects of change in fiber properties2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 3, p. 366-376Article in journal (Refereed)
  • 13.
    Bäckström, Marie
    et al.
    RISE, STFI-Packforsk.
    Hammar, Lars-Åke
    RISE, STFI-Packforsk.
    Htun, Myat
    RISE, STFI-Packforsk.
    Beatability and runnability studies of ion-exchanged unbleached kraft pulps on a pilot scale2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 1, p. 94-100Article in journal (Refereed)
    Abstract [en]

    It has earlier been shown that the counter-ion to the charged groups in the fibre has a significant effect on the beatability of fibres, but large-scale investigations of this effect are scarce in the literature. The objectives of the present study were therefore to develop a technique to ion-exchange large quantities of industrial pulp into the Na +-form using complexing agents and to study the effect of industrial-scale refining on pulp fibres in the Na +-form and how the fibres respond to industrial-like papermaking. The results show that ion-exchange can indeed be conducted on a pilot-scale using complexing agents such as DTPA. The study further indicates that an energy reduction of 50% at a given WRV or tensile index may be achieved if the fibres are converted to Na +-form prior to pilot-scale refining. By applying these techniques in full-scale production, it should thus be possible to save significant amount of energy, especially in the case of papers made from unbleached pulp that usually demands a higher degree of beating to achieve sufficient strength.

  • 14.
    Bäckström, Marie
    et al.
    RISE, Innventia.
    Melander, E.
    Brännvall, Elisabet
    RISE, Innventia.
    Study of the influence of charges on refinability of bleached softwood kraft pulp2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 4, p. 588-595Article in journal (Refereed)
  • 15.
    Bäckström, Marie
    et al.
    RISE, Innventia.
    Tubek-Lindblom, Anna
    RISE, Innventia.
    Wågberg, Lars
    RISE, Innventia.
    Studies of the influence of deflocculants and flocculants on the refining efficiency on a pilot scale2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 3, p. 319-326Article in journal (Refereed)
    Abstract [en]

    The objective of the present investigation was to study the influence of flocculants and deflocculants on refining efficiency. The refining was performed with the aid of a conical refiner at EuroFEX, and the refining response was evaluated as the change in fibre properties and in the mechanical properties of handsheets. Using the same furnish, an unbleached neverdried softwood pulp, the effect of fibre dimensions on floc strength was excluded as much as possible. The degree of flocculation was changed by addition of APAM, CPAM, guar gum and CMC. The floc strength was characterized using a parallel plate rheometer. The added chemicals, except for APAM, affected the relation between power input and gap clearance. To reach a certain power the fibres treated with guar gum, CMC or CPAM required a narrower gap clearance than the reference pulp or when APAM was added to the fibres. Refining at a narrower gap clearance increased the refining efficiency in terms of WRV and paper property development, as long as fibre length reduction could be avoided.

  • 16. Carlsson, A.
    et al.
    Söderberg, L. Daniel
    RISE, Innventia.
    Lundell, F.
    Fibre orientation measurements near a headbox wall2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 2, p. 204-212Article in journal (Refereed)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. Images containing fibres in approximately 1 mm thick slices parallel to the wall were captured at different wall distances. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres, suspended in water, at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall.

  • 17.
    Carlsson, CMG
    et al.
    YKI – Ytkemiska institutet.
    Eriksson, I
    Lindström, E
    Ström, G
    YKI – Ytkemiska institutet.
    Improved wettability of chemithermomechanical pulp by oxygen plasma treatment1994In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 9, p. 72-75,83Article in journal (Refereed)
    Abstract [en]

    Chemithermomechanical pulp has been treated by cold plasma of oxygen, nitrogen, argon or air. The wettability increases as a result of treatment by oxygen or air plasmas but decreases when argon or nitrogen plasmas are used. The initial water absorption rate can be improved by more than 100 % using an oxygen plasma. After subsequent ageing of the pulp the improvement was ca 200 %. Electron Spectroscopy for Chemical Analysis (ESCA) shows that the oxygen plasma treatment increases the oxygen content of the fibre surfaces due to oxidation and/or removal of fatty acids, resin acids, and probably also lignin. The amount of extractable material increases after the plasma treatment, probably due to oxidation and scission of the lignin and the carbohydrates. This oxidized low molecular weight material may act as a surfactant decreasing the surface tension of the absorbing liquid and thus enhance the absorption rate.

  • 18.
    Carlsson, G
    et al.
    YKI – Ytkemiska institutet.
    Ström, G
    YKI – Ytkemiska institutet.
    Annergren, G
    Water sorption and surface composition of untreated or oxygen plasma-treated chemical pulps1995In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 10, p. 17-23Article in journal (Refereed)
    Abstract [en]

    Three kraft pulps and one bisulphite pulp have been studied. The surface chemical composition was determined by means of ESCA, and water sorption was studied using a dynamic contact angle tester. The surface coverage of lignin as well as dichloromethane (DCM) extractable material was found to be considerably larger than expected from bulk measurements. The results show that DCM extractable material decreases water sorption to a larger extent than lignin. Oxygen plasma-treatment improves water sorption of pulps containing large amounts of DCM extractable material and lignin due to oxidation of these compounds. Only a few seconds of exposure is needed. After ageing the improved water sorption is unchanged for kraft pulps. However, bisulphite pulp which contains larger amount of extractable material shows a decrease in rate of water sorption.

  • 19.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Aasrød, K.
    Leinsvang, Berit
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Bouveng, Mikael
    RISE, Innventia.
    Johansson, Per-Åke
    RISE, Innventia.
    Structural effects on print-through and set-off2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, p. 596-603Article in journal (Refereed)
  • 20.
    Coppel, L.G.
    et al.
    RISE, Innventia.
    Andersson, M.
    Edström, P.
    Kinnunen, J.
    Limitations in the efficiency of fluorescent whitening agents in uncoated paper2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 3, p. 319-328Article in journal (Refereed)
  • 21.
    Coppel, L.G.
    et al.
    RISE, Innventia.
    Andersson, M.
    Neuman, M.
    Edström, P.
    Fluorescence model for multi-layer papers using conventional spectrophotometers2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 2, p. 418-425Article in journal (Refereed)
  • 22.
    Dahlgren, MAG
    et al.
    YKI – Ytkemiska institutet.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Audebert, R
    Interaction and adsorption of polyelectrolytes on mica1993In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 8, p. 62-67Article in journal (Refereed)
    Abstract [en]

    Interaction and adsorption of different polyelectrolytes onto mica was studied using the surface force technique. For highly charged polyelectrolytes in dilute aqueous salt solution, the adsorbed layer neutralizes the mica surface charge at a bulk concentration of 10-50 ppm. Upon dilution the adsorbed layers desorb slowly. When the indifferent salt concentration of the solution is increased at a constant polyelectrolyte concentration, additional adsorption takes place. Attractive interactions are present between two layers of adsorbed polyelectrolytes with a charge density of 30% or more as long as the substrate surface charge is not overcompensated strongly. This attraction, which is mainly due to bridging, is considerably stronger than the van der Waals interaction. For uncharged polyelectrolyte/surface systems, the thickness of the polyelectrolyte equilibrium layer increases with decreasing charge density. For the fully charged polyelectrolyte, the range of bridging and steric interaction indicates that the polyelectrolytes adsorb in a flat conformation on the mica surface. Desorption of the polyelectrolytes into a dilute aqueous salt solution is a slow process. For an initially slightly overcompensated system, the long-range and adhesive forces vary with time in contact with a polyelectrolyte-free solution. Initially, the adhesion force increases as the net surface charge decreases. This is due to an increased bridging attraction.

  • 23.
    Dahlvik, P
    et al.
    YKI – Ytkemiska institutet.
    Ström, G
    YKI – Ytkemiska institutet.
    Eklund, D
    Variations in calcium ion concentration and pH influencing coating colour rheology, dewatering and immobilization1997In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 12, p. 61-66Article in journal (Refereed)
    Abstract [en]

    Interparticle interactions in a coating colour are largely influeced by electrolyte concentration and suspension pH. The degree of interaction is reflected in the rheological and dewatering properties of the colour as well as in the structural properties of the immobilized coating layer. In the present study an attempt is made to correlate the degree of interparticle interaction created within coating colours by variation in calcium ion concentration and pH with the atomic absorption spectroscopy were applied to gain further information about the degree of interaction. Results showed that coating colours of a mix of calcium carbonate and clay exhibit a pronounced elastic character. The elastic response increased with calcium ino concentration. This is due to calcium calcium ions binding to the dispersing agent, making it less effective. A further cauce is the decrease in the thickness on the diffuse layer of counter ions surrounding the pigment particles. A pH-reducation further strenghened the created intrinsic three-dimensional network structure. An increase in calcium ion concentration resulted in a reduced water retention, slightly pronounced by a higher pH. The immobilization solids content as did also a lower pH. Characterization of coated layers drawn down on polyester film confirmed that a combination of a high calcium ion concentration and a reduction of pH results in a pronounced pigment interaction, reflected in a thicker layer with lower density and higher roughness.

  • 24.
    Dang, B.T.T.
    et al.
    Chalmers University of Technology.
    Brelid, H.
    Södra Innovation.
    Köhnke, Tobias
    RISE, Swerea, Swerea IVF.
    Theliander, H.
    Chalmers University of Technology.
    Effect of sodium ion concentration profile during softwood kraft pulping on delignification rate, xylan retention and reactions of hexenuronic acids2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 604-611Article in journal (Refereed)
    Abstract [en]

    The objective of this investigation was to study how different concentration profiles of sodium ions influence the delignification rate, hexenuronic acid formation/degradation and xylan retention under kraft cooking conditions. The concentration of sodium ions was varied in time between 0.52 and 3.00 mol/kg solvent, taking two different routes by the controlled addition of sodium carbonate. The reaction rates of hexenuronic acid were found to increase when the sodium ion concentration was at the higher level. Furthermore, the results implied that the kinetics of hexenuronic acid reactions responds rapidly to changes in sodium ion concentration. Delignification and the removal rates of xylan decreased rapidly after the sodium ion concentration was increased. However, when the sodium ion concentration was decreased, the response to the change was delayed. These findings indicate that effects of ionic strength on the rate of delignification and removal of xylan arise as a consequence of changes in solubility and on mass transport phenomena rather than from the rates of chemical reaction. Furthermore, the results suggest that non-dissolved xylan located in the fibre wall matrix may also sorb on cellulose surfaces relatively early on in the cook if the concentration of sodium ions is at high level. © 2014, SPCI. All rights reserved.

  • 25.
    Dang, B.T.T.
    et al.
    Chalmers University of Technology.
    Brelid, H.
    Södra Innovation.
    Köhnke, Tobias
    RISE, Swerea, Swerea IVF.
    Theliander, H.
    Chalmers University of Technology.
    Impact of ionic strength on delignification and hemicellulose removal during kraft cooking in a small-scale flow-through reactor2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 3Article in journal (Refereed)
    Abstract [en]

    The effect of ionic strength/sodium ion concentration and type of anions on the delignification rate, the retention of xylan and the reactions of hexenuronic acid during kraft cooking has been investigated. A novel, small, flow-through digester was used in the cooking experiments in order to prevent the resorption of lignin and xylan and to maintain a constant concentration of active chemicals throughout the kraft cook. An increase in ionic strength/sodium ion concentration in the cooking liquor decreases the removal rate of both lignin and xylan during kraft cooking. In general, the removal rate of xylan tends to correlate with the delignification rate. However, the present investigation finds that the retention of xylan at a given degree of delignification increases at high ionic strength/sodium ion concentration. The addition of sodium salts of carbonate or chloride to the cooking liquor was shown to increase the rate of formation/degradation reactions of hexenuronic acids and the total amount of uronic acids substituted on the xylan backbone decreases when the concentration of sodium ions increases in the cooking liquor. This promotes a decrease in the dissolution of xylan and consequently an increase in the retention of xylan in the wood residues. The obtained results demonstrate that the xylan content in the fiber wall increases at higher ionic strength/sodium ion concentration, which leads to a slight increase in pulp yield.

  • 26.
    De Magistris, Federica
    et al.
    RISE, STFI-Packforsk.
    Salmen, Lennart
    RISE, STFI-Packforsk.
    Finite element modelling of wood cell deformation transverse to the fibre axis2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 2, p. 240-246Article in journal (Refereed)
    Abstract [en]

    Modelling of wet wood under compression and combined shear and compression load was performed to simulate the mechanical pulping of wood chips in refiners. Experiments have shown that the wet fibre network exhibit two different deformation modes; an S-shape mode associated with compression and a brick-shape mode associated with combined shear and compression. To study the factors governing the mechanical behaviour of the fibre network a material model with the characteristics originating from the properties of the wood polymers was developed and was used in a three-dimensional finite element analysis. The effects of material properties were investigated by comparing models with anisotropic one-layer cell walls and orthotropic multi-layer cell walls. The deformation achieved both under compression and under combined shear and compression was found to be similar independent of the material constants used or the number of layers of the cells walls. This implies that the most important factor governing the deformation pattern of the fibre network is the cell structure itself.

  • 27.
    Duker, Elisabeth
    et al.
    RISE, STFI-Packforsk.
    Ankertors, Mikael
    RISE, STFI-Packforsk.
    Lindström, Tom
    RISE, STFI-Packforsk.
    Glad-Nordmark, Gunnel
    RISE, STFI-Packforsk.
    The use of CMC as a dry strength agent: The interplay between CMC attachment and drying2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 1, p. 65-71Article in journal (Refereed)
    Abstract [en]

    This paper deals with the ability to use high molecular weight CMC as a dry strength agent in paper and how the drying of the pulp, either before or after the CMC attachment, affects the mechanical properties of the paper. The effect of the counter-ion form used during drying and reslushing was also investigated. In the case of the calcium and hydrogen counter-ion forms, drying after CMC attachment had no impact on the attached amount. The sodium form did, however, result in some detachment of CMC. When the pulp was dried prior to CMC treatment, the counter-ion form had no effect on the attached amount. It was also shown that drying of a CMC-treated pulp reduced the positive effect of CMC on the mechanical properties. Nevertheless, the mechanical properties were still better than those of paper made from the never-dried reference pulp. The relative effect of CMC on the mechanical properties was independent of the drying strategy used and the counter-ion form did not affect the mechanical properties. However, surface carboxymethylation prior to drying resulted in sheets with better final mechanical properties than sheets made from pulp that had first been dried and then surface carboxy-methylated.

  • 28.
    Duker, Elisabeth
    et al.
    RISE, STFI-Packforsk.
    Lindström, Tom
    RISE, STFI-Packforsk.
    On the mechanisms behind the ability of CMC to enhance paper strength2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 1, p. 57-64Article in journal (Refereed)
    Abstract [en]

    The attachment of CMC to pulp is known to have a strong impact on the tensile strength properties. The mechanisms behind the strength-enhancing ability of the CMC have been investigated by studying the effect of surface carboxymethylation on some basic fibre and sheet properties. Standard methods were used for the strength evaluation, and the relative bonded area was determined from both light-scattering measurements and BET-analysis. The effect of CMC on the shear bond strength was calculated using Page’s equation. The attachment of CMC was shown to increase the shape factor and reduce the number of kinks per fibre, which is beneficial for the tensile strength. Surface carboxymethylation also increased the relative bonded area, but on a small-scale structural level detectable only using BET-analysis and not by the scattering coefficient. The sheet density was not affected by the treatment. CMC attachment also increased the shear bond strength. In order to use Page’s equation for this evaluation, the relative bonded area had to be determined by BET-analysis. The positive effect of CMC on sheet formation also contributed to an increase in tensile strength.

  • 29. Enberg, S
    et al.
    Rundlöf, M
    Paulsson, M
    Axelsson, P
    Eriksson,  Ø
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Some causes of formation of colour during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 2, no 29, p. 356-366Article in journal (Refereed)
  • 30. Enberg, S
    et al.
    Rundlöf, M
    Paulsson, M
    Axelsson, P
    Eriksson,  Ø
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The influence of process waters on optical properties during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 2, no 29, p. 344-355Article in journal (Refereed)
  • 31. Enberg, S.
    et al.
    Rundlöf, M.
    Paulsson, M.
    Johnsen, I.A.
    Axelsson, P
    The influence of process conditions during pulp storage on the optical properties of Norway spruce high-yield pulps2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, p. 203-210Article in journal (Refereed)
  • 32.
    Eriksen, O.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Holmqvist, Claes
    RISE, STFI-Packforsk.
    Mohlin, Ulla-Britt
    RISE, STFI-Packforsk.
    Fibre floc drainage - a possible cause for substantial pressure peaks in low-consistency refiners2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 3, p. 321-326Article in journal (Refereed)
    Abstract [en]

    Is floc drainage a cause for substantial pressure peaks in low-consistency refiners? High-resolution pressure measurements using a sensor mounted in a stator bar have been performed. These show that during the initial stage of a bar crossing, a substantial pressure is sometimes generated, which can reach a level of several MPa. A theoretical model that explains the pressure pulses is presented. The analysis is based on the assumption that a floc of fibres is trapped between the leading edges of the approaching bar surfaces. Water needs to be expelled from the part of the floc that is compressed and enters into the refiner gap. The hydrodynamic resistance to expel the liquid from within the floc is shown to give rise to substantial pressures in the region close to the leading edge of the rotor bar. The estimated pressures are of the same order as the measured values.

  • 33.
    Eriksen, O.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Holmqvist, Claes
    RISE, STFI-Packforsk.
    Mohlin, Ulla-Britt
    RISE, STFI-Packforsk.
    Theoretical outline of the cause for observed cavitation in a low-consistency refiner2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 3, p. 315-320Article in journal (Refereed)
    Abstract [en]

    High-frequency pressure measurements in the refining zone have exposed features that strongly indicate that cavitation occurs regularly in low-consistency refiners. In order to explain the cavitation, it is assumed that pulp fibres are trapped between opposing bars on the discs in such a way that liquid is hindered to enter into the refining gap at the leading edge of the stator bar. In order to prevent a void as the rotor bar drags liquid away from the trapped fibres, a counter flow towards the trapped fibres then needs to be set up. This necessitates a low pressure in the gap, in order that liquid from the groove in front of the rotor is accelerated into the gap at the required rate. It appears that this mechanism can yield gap pressures several hundred kPa below that in the grooves. Cavitation bubbles may then form, which subsequently collapse and cause shock waves when the pressure rises after the bar passage.

  • 34.
    Eriksson, L
    et al.
    YKI – Ytkemiska institutet.
    Alm, B
    YKI – Ytkemiska institutet.
    Effects of polyelectrolyte characteristics and flocculation conditions on fine particle floc properties1993In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 8, p. 153-159, 175Article in journal (Refereed)
    Abstract [en]

    Polystyrene latex was flocculated with cationic polyelectrolytes of different charge densities at low ionic strength and the effects of different flocculation conditions were studied. The flocs were characterized in an equipment with which the flocculation kinetics, the floc structure, the shear resistance and the ability for reflocculation after high shear can be studied in a single experiment. The structure was further investigated by SEM on freezedried flocs. With low charge density polymers the flocs had good shear resistance but limited ability to reflocculate after high shear. They consisted of compact microflocs connected into more open macrostructures and were formed by a bridging mechanism. Best floc properties seemed to be obtained with relatively mild stirring conditions during the initial flocculation. With somewhat higher charge density (≈10 %) a transition in mechanism was indicated since best shear strength and reflocculation was obtained with high intensity stirring during the initial flocculation. With medium charge density polymers the shear strength was lower and less dependent on the initial stirring rate. The size of the initial flocs was strongly decreased by in-creasing initial mixing intensity. On the other hand, the reflocculation was better than with low charge density polymers, and it also improved with increasing initial stirring rate. The flocculation was mainly due to charge neutralization with limited contribution of bridging and electrostatic attractions in the total attractive force. With high charge density polymers the shear resistance was somewhat better than for medium charged polymers and high initial stirring intensity seemed to be favourable also in this case. The good reflocculation however, seemed to depend on the initial stirring intensity in a non-monotonous way. The structure of the flocs had voids on all length scales because of a flocculation mechanism with strong and close contacts between the primary particles.

  • 35.
    Fellers, C.
    et al.
    RISE, Innventia.
    Östlund, S.
    Mäkelä, P.
    RISE, Innventia.
    Evaluation of the Scott bond test method2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 2, p. 231-236Article in journal (Refereed)
  • 36. Furó, I
    et al.
    Daicic, J
    YKI – Ytkemiska institutet.
    NMR cryoporometry: a novel method for the investigation of the pore structure of paper and paper coatings1999In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 14, p. 221-225Article in journal (Refereed)
    Abstract [en]

    Many of the properties that paper coatings are designed to modify are determined to varying degrees by the nature of the pore space that interweaves the consolidated matrix. It is therefore highly useful to characterize the pore size distribution of paper coatings. Commonly used methods include mercury porosimetry, image analysis of scanning electron micrographs, and stain imbibition. Here, we describe a method, NMR cryoporometry, which is novel in its application to pores in paper and paper coating and is particularly suitable for measuring small pore sizes in the range of 1 to 100 nm. Such pore sizes are difficult to access with other techniques. The method is based on the principle of the freezing and melting temperature suppression of fluids entrapped within pores. A general outline of the technique is given, and an example of a cryoporometry measurement on a coated paper sample is described.

  • 37.
    Gimaker, M.
    et al.
    RISE, Innventia.
    Östlund, M.
    Östlund, S.
    Wågberg, L.
    Influence of beating and chemical additives on residual stresses in paper2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 4, p. 445451-Article in journal (Refereed)
  • 38. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Axelsson, P.
    Engstrand, P.
    Peroxide-based ATMP refining of Spruce: Energy efficiency, fibre properties and pulp quality2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 47-63Article in journal (Refereed)
  • 39. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Role of equipment configuration and process chemicals in peroxide-based ATMP refining of spruce2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 233-247Article in journal (Refereed)
  • 40. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Olson, J.
    Luukkonen, A.
    Fibre and fines quality development in pilot scale high and low consistency refining of ATMP2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, p. 872-881Article in journal (Refereed)
  • 41.
    Granberg, Hjalmar
    et al.
    RISE, Innventia.
    Coppel, L.G.
    RISE, Innventia.
    Eita, M.
    De, Mayolo E.A.
    Arwin, H.
    Wågberg, L.
    Dynamics of moisture interaction with polyelectrolyte multilayers containing nanofibrillated cellulose2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 2, p. 496-499Article in journal (Refereed)
  • 42. Grön, J
    et al.
    Dahlvik, P
    Ström, G
    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.

  • 43.
    Hagman, Anton
    et al.
    RISE, Innventia.
    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.

  • 44.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Theliander, H.
    Chalmers University of Engineering.
    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. © 2015, SPCI. All rights reserved.

  • 45. Hii, C.
    et al.
    Gregersen, Ø.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öjvind
    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, p. 388-396Article in journal (Refereed)
  • 46. Hii, C.
    et al.
    Gregersen, Ø.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öjvind
    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, p. 790-797Article in journal (Refereed)
  • 47. Hii, C.
    et al.
    Gregersen, Ø.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öjvind
    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, p. 798-805Article in journal (Refereed)
  • 48.
    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.

  • 49.
    Hyll, Kari
    RISE, Innventia.
    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.

  • 50.
    Hyll, Kari
    et al.
    RISE, Innventia.
    Björk, Elisabeth
    RISE, Innventia.
    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 &mu;m/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 &mu;m/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.

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