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  • 151.
    Tysen, Aron
    et al.
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Nilsson, Lars
    Karlstad University, Sweden.
    The influence of grammage and pulp type on through air drying2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 4, p. 651-659Article in journal (Refereed)
    Abstract [en]

    The influence of grammage and pulp type on through air drying was studied. The temperature of a sample was measured during the drying process and the observed temperature changes were used to evaluate the drying process. Laboratory sheets with grammages 15-60 g/m2, from two softwood and two hardwood bleached chemical pulps were used. All samples were analysed with respect to formation, flow resistance, modified permeability, mean drying time, non-uniformity of drying time, and area- and mass-specific drying rate. The pulps had different modified permeabilities but showed similar behaviour when analysed as a function of grammage. A constant value was found for higher grammages, while an increase in modified permeability was found at decreasingly low grammages. Almost all pulp and grammage combinations had similar areaspecific drying rates, but the mass-specific drying rates decreased with grammage. However, the samples with lower grammages had mass specific drying rates independent of modified permeability, where samples with increasing grammage showed an increasing dependency. This implies that the drying efficiency at low grammages was not controlled by the volume flow of the drying air. A good correlation was found between energy needed to evaporate water and energy supplied by the drying air as estimated from the surface temperature and air flow measurement. The surface temperature can therefore be used to quantify the drying process.

  • 152.
    Tysen, Aron
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy.
    Vomhoff, Hannes
    Holmen, Sweden.
    Nilsson, Lars
    Karlstad university, Sweden.
    Through air drying assisted by infrared radiation: The influence of radiator power on drying rates and temperature2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669Article in journal (Refereed)
    Abstract [en]

    The use of infrared radiation for heating the web in the through air drying process was investigated in lab scale. The hypothesis was that infrared radiation should be a more efficient method to transfer drying energy to the wet web compared to hot air, but that a certain air flow is still required as a transport medium for the evaporated water. A trial program comprising handsheets made of two types of bleached chemical pulps, five grammages (15, 22, 30 and 60 g/m2), and dried with five radiator power levels was performed on a lab scale through air drying equipment. Drying times of the samples were determined from temperature data recorded with an infrared camera. The use of infrared radiation shortened drying times, especially for low grammage samples. The shortening of the drying time ranged between 10 and 45 %. The most substantial shortenings were obtained for the lowest grammages and the highest radiator power level. However, the increase of power did not linearly shorten drying time. After an initial shortening at the lowest power level, the positive effect of the IR heating decreased as the power was further increased.

  • 153.
    Valtakari, Dimitar
    et al.
    Åbo Akademi University, Finland.
    Stepien, Milena
    AGH University of Science and Technology, Poland.
    Haapanen, Janne
    Tampere University of Technology, Finland.
    Teisala, Hannu
    Tampere University of Technology, Finland.
    Tuominen, Mikko
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Kuusipalo, Jurkka
    Tampere University of Technology, Finland.
    Mäkelä, Jyrki M.
    Tampere University of Technology, Finland.
    Toivakka, Martti
    Tampere University of Technology, Finland.
    Saarinen, Jarkko J.
    Åbo Akademi University, Finland.
    Planar fluidic channels on TiO2 nanoparticle coated paperboard2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 2, p. 232-238Article in journal (Refereed)
    Abstract [en]

    A new design for permanent, low-cost, and planar fluidic channels on TiO2 nanoparticle coated paperboard is demonstrated. Initially superhydrophobic TiO2 nanoparticle coatings can be converted to hydrophilic by ultraviolet (UVA) light, and fluidic channels can be generated. A simple water treatment after the UVA illumination converts the channels permanent when nanoparticles are removed from the illuminated and wetted areas as shown by water contact angle, FE-SEM, XPS, and ToF-SIMS analysis. This suggests new routes for inexpensive, easy to use point-of-care diagnostics based on planar fluidic channels.

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  • 154. Voltaire, J
    et al.
    Fogden, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Craig, V
    Jansson, D
    Jacobsson, N
    Acoustic investigation of cavitation noise from offset ink film splitting2006In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, no 3, p. 314-322Article in journal (Refereed)
    Abstract [en]

    The acoustic signal from the nip during film splitting between inked rollers and on ink transfer to paper was investigated on laboratory scale, using two sheet-fed offset inks (based on mineral oil and vegetable oil) and two coated fine papers (glossy and matte). Film splitting emits a broad noiselike acoustic spectrum in the range 5-50 kHz, from which the two simplest measures of average power and average frequency were derived. Using these two measures, four characteristic regimes of film splitting on the rollers could be distinguished as a function of ink load. Moreover, for intermediate amounts, average power was found to be accurately predicted by a simplistic model of sound produced by cavity expansion due to the under-pressure in the nip exit, thus providing a physical interpretation of the nip noise emission. For printing, the average power was higher for the glossy paper than the matte, presumably due to a more efficient sealing of the nip, or onset of ink setting. The vegetable oil-based ink gave higher power than its mineral oil counterpart. These results were found to be consistent with longer-time measurements of tack evolution from the Ink Surface Interaction Tester. This correlation and the verified theory thus provide support to practical applications of acoustic emission as an on-press monitoring tool.

  • 155. Voltaire, J
    et al.
    Gujjari, C
    Batchelor, W
    Fogden, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Acoustic emission and tack of heat-set inks during setting on MWC-papers and fountain solution emulsification2007In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, p. 432-440Article in journal (Refereed)
  • 156. Voltaire, J
    et al.
    Mattila, U
    Fogden, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Nieminen, S
    Reinius, H
    Acoustic characterisation of film splitting in a HSWO printing nip2007In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, p. 424-431Article in journal (Refereed)
  • 157.
    Wallmeier, Malte
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Barbier, Christophe
    BillerudKorsnäs AB, Sweden.
    Beckmann, Felix
    Institute of Materials Research, Germany.
    Brandberg, August
    KTH Royal Institute of Technology, Sweden.
    Holmqvist, Claes
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Kulachenko, Artem
    KTH Royal Institute of Technology, Sweden.
    Moosmann, Julian
    Institute of Materials Research, Germany.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Pettersson, Torbjörn
    KTH Royal Institute of Technology, Sweden.
    Phenomenological analysis of constrained in-plane compression of paperboard using micro-computed tomography Imaging2021In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 36, no 3, p. 491-Article in journal (Refereed)
    Abstract [en]

    Large deformations under in-plane compression of paperboard appear in forming processes like hydroforming, pressforming and deep drawing, but the mechanisms of deformation have not been studied on a micromechanical level. A constrained in-plane compression test is presented. This test allows for in-plane compression, buckling, wrinkling and compaction. The constrained compression test is realized using a DEBEN CT-500 in-situ tester for laboratory microtomography and synchrotron microtomography. Experiments with five different materials spanning from laboratory handsheets to commercially available multi-layered paperboards are performed. Image processing is used to observe the local out-of-plane fiber orientation and compaction. A phenomenological investigation of the deformation behavior of these materials is presented. Delamination is found to be the primary mechanisms of failure in the multi-layered boards. Furthermore, a porous network structure, created by using long and minimally refined softwood fibers, is found to facilitate the formation of uniform wrinkles and compaction.

  • 158.
    Wernersson Brodin, F.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Weiby Gregersen, Ø
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose nanofibrils: Challenges and possibilities as a paper additive or coating material – A review2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 1, no 29, p. 156-166Article in journal (Refereed)
  • 159. Wickman, M
    et al.
    Beadle, A
    Gurrera i Magrané, L
    Sebring, T
    Larsson, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    The effect of alkyd resin composition on the adsorption on calcium carbonate1994In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 9, p. 94-100Article in journal (Refereed)
    Abstract [en]

    In this paper we present adsorption studies of alkyd resins, frequently used in printing inks, on different calcium carbonate surfaces. The adsorption isotherms indicate that the interactions between alkyd resins and precipitated calcium carbonate are strong. Studies of alkyd resins of different composition clearly show the impact of molecular weight as well as oil length on the adsorption strength. The explanations for this are discussed in terms of compatibility with the solvent used in the study and in terms of alkyd resin molecular weight distribution. Finally, we show that adding a dispersant to the calcium carbonate alters the surface properties and that this affects the adsorption of alkyd resins negatively.

  • 160. Yang, L
    et al.
    Fogden, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Pauler, N
    Sävborg, Ö
    Kruse, B
    A novel method for studying ink penetration of a print2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, p. 423-430Article in journal (Refereed)
    Abstract [en]

    A method combining microscopy with image analysis for studying ink penetration of ink-jet prints has been proposed. Prints on paper substrates of various material compositions have been microtomed, imaged with optical microscopy, and analyzed with image processing. The penetration depth and distribution of the ink-jet dye in the paper, which depend on the material compositions of the substrates and printed ink volumes, are then obtained by means of statistical analysis. The study focuses on uncoated fine papers, including five types of hand-sheets and two commercial papers. It is observed that ink penetration can be significantly reduced by adding internal sizing (hydrophobizing) chemicals in the hand-sheet making, while it is relatively less affected by addition of filler and fluorescent whitening agent (FWA). Ink volume obviously influences the depth of its penetration, with depth increasing linearly for higher ink volumes but displaying a disproportionately shallow penetration for smaller applied volumes.

  • 161.
    Yang, Li
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Mechanical response of paperboard to rapid compression2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 4, p. 615-623Article in journal (Refereed)
    Abstract [en]

    ZD-tester is a measurement technique for rapid compression in Z-direction. The strain rate of compression of this device is far beyond the ordinary mechanical testing methods applied in papermaking industries. Thus, it provides insights to the material responses which are relevant to industrial applications, e. g. calendaring, printing, etc where the strain rate ranges from hundreds to thousands per second. A physics model that describes the dynamic process of the probe has been developed, where a linear Maxwell model is used to account for the viscoelasticity of paperboard. The simulation has successfully reproduced both the general features and quantitative details of the experiment. The model reveals that the ratio of the elastic modulus to the viscosity modulus of the material governs the amplitude attenuation while the angular frequency of the striking-rebounding cycle depends mainly on the elastic modulus. The dropping height determines the initial striking velocity but has no direct impact on either attenuation or angular frequency. The model and simulation provided interpretations of both experimental observations and dynamic behaviours of the material. With help of simulation, the impacts of the individual parameters, e. g. the Young's modulus, E, the viscosity modulus, η, and the drop height, H, were also explored. 

  • 162.
    Ziesig, Rufus
    et al.
    RISE, Innventia.
    Sedin, Maria
    RISE, Innventia.
    Tomani, Per
    RISE, Innventia.
    Theliander, Hans
    RISE, Innventia. Chalmers University of Technology, Sweden.
    Production of a pure lignin product, Part 3: Distribution and removal of inorganics from softwood lignin2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 2, p. 199-206Article in journal (Refereed)
    Abstract [en]

    Future high value lignin-based products, such as carbon fibers, require a lignin raw material essentially free from inorganic impurities. Lignin of low inorganic content can be separated from kraft black liquor by the LignoBoost process. This laboratory scale study focuses on the effect of process parameters, such as pH and retention time in re-suspension, on the content of inorganic impurities in the LignoBoost lignin. Black liquor from pulping of softwood was used in this study. Specific attention was paid to the elements Na, K, Al, Ba, Ca, Fe, Mg, Mn and Si. It was found that the softwood lignin contained significantly less Ca, resulting in lower ash content, than eucalyptus lignin separated in earlier studies made in this series. Inorganic particles, containing for example Ca-O and Na-Al-Si, were observed in the washed lignin. Prolonged retention time in the re-suspension stage reduced the content of Ca, Mn, Mg, Fe and Si in the washed lignin. A reduction of the content by 30-50% after 24 h was possible. The rate at which these elements are removed from the agglomerates was found to be dependent on the mixing conditions, which indicates that the mass transfer in the liquid film around the particles is of importance for the total mass transfer resistance.

  • 163.
    Åslund, Peter
    et al.
    RISE, STFI-Packforsk.
    Vomhoff, H.
    RISE, STFI-Packforsk.
    Dewatering mechanisms and their influence on suction box dewatering processes: A literature review2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 389-397Article, review/survey (Refereed)
    Abstract [en]

    This review summarizes the present knowledge of suction box dewatering mechanisms. In addition, existing and novel suction box dewatering processes are described for applications in the pulp and paper industry. Three mechanisms that determine the dry content of the web after suction box dewatering are identified, viz. web compression, displacement of water by air, and rewetting. Earlier work focused mainly on the influence of web properties and process parameters for the achievable dry content. That work did not give any information concerning the relative importance of the three mechanisms. There was no measurement of web compression or water displacement. Furthermore, the occurrence of rewetting was neglected by many researchers. A deeper knowledge and, above all, direct measurements are required to better describe suction box dewatering. Some interesting modified suction box dewatering processes were presented in the literature. For example, the use of a membrane on top of the web during dewatering is believed to have the potential for an increase in dry content and energy savings. This increase in dry content is consequently believed to be a result of an increase in web compression.

  • 164.
    Åslund, Peter
    et al.
    RISE, Swerea, Swerea KIMAB.
    Vomhoff, H.
    STFI-Packforsk AB.
    Waljanson, A.
    STFI-Packforsk AB.
    The deformation of chemical and mechanical pulp webs during suction box dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 403-408Article in journal (Refereed)
    Abstract [en]

    The deformation of the paper web during and after a suction pulse on initially saturated fibre web made of chemical and mechanical pulp was investigated. A laboratory suction box was used, where the suction time and pressure drop could be varied and controlled. During the experiments, the web thickness, the air flow through the web and the suction pressure were recorded and after the experiments, the dry content of the web was determined. A large deformation was observed when the suction pulse was applied. After the suction pulse, a considerable expansion of the web took place, probably an effect of rewetting. The compression of the web appeared to be the most important dewatering mechanism increasing the dry content of the web. However, if the web is not separated from the forming fabric, rewetting after the suction pulse will greatly reduce the dry content.

  • 165.
    Ņslund, Peter
    et al.
    RISE, STFI-Packforsk.
    Vomhoff, Hannes
    RISE, STFI-Packforsk.
    Evaluation of membrane-assisted dewatering on a pilot paper machine2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 2, p. 152-155Article in journal (Refereed)
    Abstract [en]

    A membrane-assisted dewatering process was evaluated on a pilot paper machine. In this process, a membrane is located on top of the wet web when it passes over the suction box in the forming section. The intentions are twofold. Firstly, the dry content of the web should be increased by a more uniform compression, primarily in the thickness direction. Secondly, the airflow into the suction box should be reduced. The trials were performed using a specially designed membrane loop located at the end of the fourdrinier forming section of STFI-Packforsk’s pilot paper machine EuroFEX. Two different membranes were tested. The use of a membrane resulted in a significant decrease in air consumption to achieve the same dry content of the web at the end of the wire section. To increase the dry content of the web, the structure of the membrane is important.

  • 166.
    Åslund, Peter
    et al.
    RISE, STFI-Packforsk.
    Vomhoff, Hannes
    RISE, STFI-Packforsk.
    Method for studying the deformation of a fibre web during a suction pulse2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 398-402Article in journal (Refereed)
    Abstract [en]

    A laboratory suction box was built to study the dynamic thickness deformation of a fibre web during a suction pulse. Both the pressure in the suction box and the duration of the suction pulse are adjustable in ranges of 0 to -40 kPa and 50 ms to 10 s, respectively. During and after the suction pulse, the web thickness and the suction pressures can be measured. Furthermore, the air flow through the web can be calculated after the experiment. The first evaluation of the performance of the laboratory suction box shows that the web is considerably compressedaaaa especially during the initial phase of the suction pulse. This indicates that web compression is an important dewatering mechanism. After the suction pulse, a rapid and significant web expansion was observed, implying that considerable rewetting probably occurs.

  • 167.
    Åslund, Peter
    et al.
    RISE, STFI-Packforsk.
    Vomhoff, Hannes
    RISE, STFI-Packforsk.
    Web deformation during membrane-assisted dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 415-419Article in journal (Refereed)
    Abstract [en]

    The potential of membrane-assisted dewatering was evaluated on a laboratory suction box. Different membranes, one impermeable and two permeable membranes were placed on top of the wet web, while a suction pulse was exerted underneath the web. The deformation of the wet web and the dry content of the web were determined approx. 30 seconds after the suction pulse. The results of these experiments were compared with results of those carried out without a membrane. A significantly higher web compression was observed at the end of the suction pulse when a membrane was used. The increased web compression that occurred when using a membrane corresponded to a dry content of 3 to 4%. The highest dry content values were obtained, however, when no membrane was applied. This contradiction was interpreted as a higher rewetting after the suction pulse when a membrane was used. Here, due to the reduced air flow through both the web and the forming fabric, it is likely that more water was available in the forming fabric for rewetting. Apparently, the air flow removed water from the forming fabric that otherwise would have been rewetted by the web.

  • 168.
    Åslund, Peter
    et al.
    RISE, STFI-Packforsk.
    Vomhoff, Hannes
    RISE, STFI-Packforsk.
    Waljanson, Alexander
    RISE, STFI-Packforsk.
    External rewetting after suction box dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 409-414Article in journal (Refereed)
    Abstract [en]

    A method has been developed to enable external rewetting to be measured during suction box dewatering. In a laboratory suction box, webs were instantaneously separated from the forming fabric at defined times, both during and after the suction pulse. External rewetting was measured for webs of mechanical (50, 100 g/m2) and chemical pulp (100, 200 g/m 2). Suction pulses with a pressure drop of 10 and 40 kPa, and duration of 50 to 1000 ms were used. A considerable external rewetting was observed occurring primarily directly after the end of the suction pulse. Under the process conditions investigated, rewetting accounted for a dry content decrease of between 3 and 6%.

1234 151 - 168 of 168
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