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  • 1. Anderbrant, Olle
    et al.
    Lyons, D. Barry
    Bång, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Högberg, Hans-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Sex Pheromone of the Introduced Pine Sawfly, Diprion similis (Diprionidae), Revisited: No Activity of Earlier Reported SynergistsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Extracts of Diprion similis females were found to contain about 15 ng of the sex pheromone precursor 3,7-dimethylpentadecan-2-ol per female. When analysing the extracts after derivatisation with (2S)-2-acetoxypropionyl chloride, we found that the major stereoisomer in the extract was (2S,3R,7R)-3,7-dimethylpentadecan-2-ol. Also other stereoisomers of 3,7-dimethylpentadecan-2-ol were identified in the extract namely, 1% of (2R,3S,7S) , 0.3% (2R,3R,7R) and 0.4% of (2R,3R,7S). An unknown fifth substance showed an identical spectrum to 3,7-dimethylpentadecan-2-ol, both in SIM and full scan mode. In field tests in Ontario, Canada, the earlier identified main pheromone component, viz. the propanoate of (2S,3R,7R)-3,7-dimethylpentadecan-2-ol, was tested alone and in combination with other stereoisomers, earlier reported to be synergistic. In none of the tests were any synergistic effects detected and the threo four-isomer blend was as attractive as the pure main compound. Thus, one of the few examples of a diprionid sawfly using more than one substance in its sex pheromone could not be confirmed. The results also suggest that monitoring programs can use the more easily synthesized threo-blend without losing efficiency.

  • 2.
    Backlund, Hans-Olof
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Gradin, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Study of tangential forces and temperature profiles in commercial refiners2003Inngår i: 2003 International Mechanical Pulping Conference, 2003, s. 379-388Konferansepaper (Fagfellevurdert)
  • 3. Branström, J.
    et al.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sandström, P.
    Ruel, K.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Compression wood in knots and the effect on surface roughness.2005Inngår i: proceedings from IMPC 2005, 2005Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The microstructural and ultrastructural characteristics of knot wood were examined and related to paper properties. Norway spruce (Picea abies) chips were laboratory fractionated and sorted into a knot containing assortment and a non knot containing reference assortment. The proportions of compression wood in these two assortments were then assessed and the two chip assortments refined in pilot refiners. The knot containing portion was divided into wood from the upper branch, wood from the lower branch compression wood and wood surrounding the branch. Fibres from the three knotwood portions and the reference chips were extracted and measurements were made of fibre properties including fibre length, fibre width and cell wall thickness. The two chip assortments were refined in a pilot plant and the surface properties of laboratory sheets were measured. The knot containing chips had adverse effects on several paper properties. However, no clear relationship was established between surface roughness and the presence of compression wood fibres in knot wood. (6 fig, 12 ref)

  • 4.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Paulsson, Magnus
    Inhibition of light-induced brightness reversion of high-yield pulps: the UV-screening properties of coating layers containing kaolin or calcium carbonate pigments2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 3, s. 350-355Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A newly developed method making it possible to study the reflectance/transmittance of thin coating layers and to link this to the inhibition of the light-induced yellowing, was used to describe the photo-stabilising properties of different types of commercial kaolin and calcium carbonate pigments. A base paper produced from a hydrogen-peroxide-bleached birch chemithermomechanical pulp (CTMP) was used throughout the study.The transmittance of the coating layers in the UV-region (300-385 nm) was found to be very low (below 1.0% at coat weights < 5g/m2) for all of the tested pigments, it strongly depends on the coat weight especially for coat weights below 10 g/m2. The kaolin pigments examined were found to be better in inhibiting the brightness reversion compared to the calcium carbonate pigments, even though the differences between the pigment types were only a few brightness units. The coating layer was, however, able to conceal some of the colour formed through the light-induce brightness reversion. For example, a coating layer consisting of kaolin pigments (coat weight of 15.6 g/m2) could conceal about 30% of the discoloration of the CTMP base paper.

  • 5.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Paulsson, Martin
    Rundlöf, Mats
    A novel method of studying the ability of coating layer to retard the photo-yellowing of the base paper2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 3, s. 343-349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method was developed which made it possible to study the reflectance/transmittance of thin coating layers and to link this to the inhibition of the light-induced yellowing. The ability of a coating layer to retard the photo-yellowing of a hydrogen-peroxide-bleached birch chemithermomechanical pulp (CTMP) is exemplified using this method. It is shown that the repeatability of the model system is excellent, even for coat weights below 10 g/m2. Furthermore, the transmittance in the UV-region is strongly correlated with the coating layers ability to protect the birch CTMP against photo-yellowing.

  • 6.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Paulsson, M
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Influence of coating formulation on light-induced brightness stability of mechanical and chemimechanical pulp sheets2005Inngår i: International Mechanical Pulping Conference: IMPC 2005, Oslo, Norway, 7-9 June 2005, 2005, s. 339-343Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The light-induced brightness reversion of different types of high-yield pulps has been studied under accelerated and long-term ambient ageing conditions. It was found that accelerated ageing (xenon lamp used as light source) overestimates the yellowing tendencies of hardwood pulps, whereas it was possible to predict the yellowing characteristics of softwood pulps. The lignin content of the pulps was found to be correlated to the degree of photo-yellowing for long-term ambient ageing. A model system was developed which made it possible to study the reflectance/transmittance of thin coating layers and to link this to the inhibition of the light-induced yellowing. The yellowing characteristics of a coated birch CTMP is exemplified using the evolved model system.

  • 7.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Paulsson, M.
    Rundlöf, Magnus
    Discolouration of mechanical and chemimechanical pulps: influence of wood raw material, process and ageing method2008Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, nr 1, s. 14-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The change in colour of a wide range of unbleached and bleached high-yield pulps was assessed using the CIELAB colour system. The influence of ageing method, pulping process and wood raw material is discussed.

  • 8.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Paulsson, Magnus
    Light-induced yellowing of mechanical and chemimechanical pulp sheets: influence of wood raw material, process and ageing method2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 1, s. 117-123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The light-induced brightness reversion of different types of unbleached and bleached high-yield pulps was studied under both accelerated and long-term ambient light-induced ageing conditions. It was found that accelerated ageing conditions that mimic indoor daylight exposures overestimate the yellowing tendencies of hardwood high-yield pulps (especially aspen pulps) compared to long-term ambient aging with no indirect sunlight present. It was, however, possible to predict the yellowing characteristics of softwood high-yield pulps. The lignin content of the pulps was found to be strongly correlated with the degree of photo-yellowing in the case of long-term ambient light-induced ageing. The presence of small amounts of birch chemithermomechanical pulp (CTMP) in a fine paper furnish resulted in extensive light-induced discoloration. The extent of photo-yellowing was found to be nearly linearly related to the amount of birch CTMP in the paper.

  • 9.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Paulsson, Magnus
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    A novel method for studying the photo-stabilising properties of coating layers2006Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A new model system was developed which made it possible to study the reflectance and transmittance of thin coating layers (<10 g/m2) in a reproducible way, and to link this to the inhibition of the light-induced yellowing (Figure 1). The UV/VIS-screening properties of coatings of different coat weights containing common pigments such as kaolin, calcium carbonate (ground or precipitated) and titanium dioxide will be reported. The ability of a coating layer to protect a birch CTMP from light-induced discoloration will be exemplified using the evolved model system. An estimation of the contribution of different wavelength regions of the illuminating light to the photo-yellowing of various types of materials will also be shown. The developed method is a valuable tool for future photo-yellowing studies as well as for optimisation of the pigment coating formulation for various paper grades.

  • 10.
    Fjellström, Helena
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Paulsson, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    The UV-screening properties of coating layers: The influence of pigments, binders and additives2009Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, nr 2, s. 206-212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability of coating colours to obstruct ultraviolet (UV) radiation in the 300-385 nm region was examined with the aim of finding the best photo-stabilising formulation to inhibit discoloration of high-yield pulps. The influence of pigment type, bleaching of the pigments, pigment size, pigment size distribution, type of binder and addition of U-V-absorbing compounds were examined using a newly developed method for studying the reflectance and transmittance properties of thin coating layers.

    The pigment type and coat weight was found to be the most important factors for reducing the transmittance of UV-radiation. Kaolin clays were more effective than calcium carbonate pigments and are therefore a better coating pigment for photostability reasons. Bleaching of the pigments, resulted in an overall minor decrease in transmittance for both kaolin and ground calcium carbonate (GCC) pigments, especially at low coat weights. Bleaching of the pigments changed the particle size distribution somewhat, which probably alters the structure in the coating layer. Precipitated calcium carbonate (PCC) pigments have a higher UV-screening potential compared to GCC pigments and should therefore be a better choice among the calcium carbonates. It was further concluded that a narrow pigment size distribution was beneficial for reducing the amount of transmitted UV-radiation that reaches the base paper. Styrene butadiene latex and polyvinylpyrrolidone were better in reducing the transmittance in the UV-region than polyvinyl alcohol.

    Adding a fluorescent whitening agent to a coating colour decreased the transmittance in the UV-region when the pigment was of the GCC type, and increased the transmittance when kaolin pigment was used. Addition of titanium dioxide (3 parts) to a coating colour containing kaolin pigment blocked about 90% of the UV-radiation at a coat weight of 10 g/m(2), which is a common coat weight for a single coated paper. Another possibility is to double coat to increase the coat weight, which turns the transmittance factor closed to zero.

  • 11.
    Friman, Linda
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Högberg, Hans-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Agnemo, Roland
    Tannin-iron impregnated thermomechanical pulp: Part I: Effects of extractions and heat on brightness2004Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 19, nr 2, s. 229-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tannins are polyphenolic compounds found mainly in bark. When reacting with iron, they form strongly coloured complexes, which through contamination from the bark may induce a brightness decrease of mechanical pulps. Wood itself contains phenolic compounds, which can form coloured complexes with iron. We have investigated gallotannin as a model for metal-binding sites in the pulp. The behaviour of tannin-iron complexes in solution and in pulp has been studied. In aqueous solution, the tannin-iron complexes can be decolourised by the addition of diethylenetriaminepentaacetic acid (DTPA). The colour of the tannin-iron complexes was very pH-dependent. Thus in solution, these were decolourised at low pH and at high pH the spectral characteristics were changed substantially. We have studied the effects on brightness and heatinduced brightness loss of the impregnation of thermomechanical pulp (TMP) with 30 parts per million iron (ppm i.e. mg/kg) either as iron or tannin-iron as well as the possibility to decrease such effects by using various solvent extractions. The tannin-iron impregnation causes a decrease in ISO-brightness of approximately 3% and an increase in the light absorption coefficient (k) by approximately 2 m(2)/kg at the tannin-iron absorbance maximum. 565 run. These effects are approximately ten times higher than those observed for the Pulp only impregnated with iron. Extraction with 1% by weight of DTPA provides a way to reduce the brightness decrease induced by the tanniniron complexes and the observed decrease can be attributed to removal of iron from the pulp. Acid extraction was the most efficient way to reduce the iron content in the pulps and to decoulorise the tannin-iron impregnated pulp. However, after acid extraction of iron impregnated Pulps, new chromophores were evidently formed. Addition of the reducing agent, sulphite, to extractions had no effect on the iron removal or the brightness of the impregnated pulps. The heat-induced brightness loss is not influenced by the addition of tannin-iron or iron. The brightness loss caused by heat was lower for pulps extracted with DTPA.

  • 12.
    Friman, Linda
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Högberg, Hans-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Agnemo, Roland
    Tannin-iron impregnated thermomechanical pulp: Part II: Bleachability and brightness reversion2004Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 19, nr 4, s. 525-531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tannins are polymeric, phenolic constituents found in the bark of pine and spruce. When reacting with iron ions, tannins form strongly coloured complexes. Thus, the presence of bark in the mechanical pulping process leads to decreased brightness of the pulp. In order to evaluate the effects of the presence of iron on the properties of pulp, we have impregnated thermomechanical pulp (TMP) with 30 parts per million (ppm i.e. mg/kg) iron either as Fe3+ or as tannin-iron complexes and studied how such treatments affect bleachability and heat-induced brightness reversion. The bleaching agents studied are hydrogen peroxide and sodium dithionite. Treatment of the tannin-iron impregnated pulp with 1% by weight of diethylenetriaminepentaacetic acid (DTPA) before bleaching with 4% hydrogen peroxide almost eliminated the brightness loss caused by the impregnation. Such a treatment also removed all of the added iron from both the tannin-iron and FeCl3 impregnated pulps. Approximately 5% more of the added peroxide was required for oxidation of the tannins in the tannin-iron impregnated pulp. Contrary to what was observed with peroxide bleaching, dithionite bleaching did not reduce the amount of iron in the pulps. Instead, the added iron and tannin-iron negatively affected the dithionite bleaching, even if the pulps were extracted with DTPA before bleaching. It should therefore be advantageous to first bleach with peroxide, which removes most of the iron, and then with dithionite. Compared with dithionite, peroxide yields a more efficient bleaching. The reason for this is that the former reduces the light absorption coefficient, the k-value, more efficiently in the whole visible spectrum, whereas dithionite reduces it mainly at shorter wavelengths. In our experiments, the addition of tannin-iron or FeCl3 to the untreated pulp did not increase heat-induced brightness reversion. This is Supported by the fact that although extraction of the samples with DTPA before bleaching lowered the iron content slightly, it-did not affect the brightness reversion. The initial brightness reversion of the dithionite bleached pulps was larger than that observed for the peroxide bleached pulps.

  • 13.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Mechanical Pulping2009Inngår i: Pulping Chemistry and Technology / [ed] Ek, M., Gellerstedt, G., Henriksson, G., Stockholm: KTH Royal Institute of Technology, 2009, s. 57-90Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 14.
    Höglund, Hans
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Pettersson, Gunilla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    A paper or paperboard product comprising at least one ply containing high yield pulp and its production method2018Patent (Annet (populærvitenskap, debatt, mm))
  • 15.
    Klinga, Niklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Sandberg, C
    Holmen Paper Development Centre, Braviken Paper Mill, SE-601 88 Norrköping, Sweden.
    Energy efficient high quality CTMP for paperboard2007Inngår i: International Mechanical Pulping Conference 2007, TAPPI, 2007, Vol. 1, s. 370-380Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper discusses the relationship between bulk and internal bond strength in paper sheets and their dependency on fibre length, fibre flexibility and fibre surface properties. It also discusses an interesting process concept for manufacturing of energy efficient high quality CTMP for paperboard. Post-refining pilot trials of spruce HTCTMP with an initial freeness of 740 ml were carried out at Metso Paper R&D in Sundsvall, Sweden. Both gentle high consistency and severe low consistency post-refining were performed. High consistency post-refining, at high energy input, gave freeness levels below 70 ml and still preserved the fibre length. These fibres were characterised by a very high flexibility giving sheets with a tensile index as high as 64 kNm/kg. Long fibres can however cause formation problems on a board machine which in turn can lead to poor surface properties, hence shorter fibres are from that perspective desirable. The low consistency post-refining resulted in a rapid drop in freeness due to fibre cutting. This was achieved at an extremely low specific energy input, which probably preserved most of the original fibre stiffness. In spite of this low energy input it was possible to reach the same Z-strength at a given bulk, as for the high consistency post-refined pulp. This implied that high bulk at certain internal bond strength could be,...;. achieved with stiff fibres even though the content of long fibres was low. Energy efficient low consistency postrefining of spruce HTCTMP yields high quality pulp at a total energy input of ∼800 kWh/admt and is an-interesting process concept for production of pulps intended for paperboard.

  • 16.
    Klinga, Niklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Sandberg, C
    Energy efficient high quality CTMP for paperboard2008Inngår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 34, nr 2, s. 98-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper discusses the relationship between bulk and internal bond strength in paper sheets and their dependency on fibre length, fibre flexibility and fibre surface properties. It also discusses an interesting process concept for manufacturing of energy efficient high quality CTMP for paperboard. Post-refining pilot trials of spruce HTCTMP with an initial freeness of 740 ml were carried out at Metso Paper R&D in Sundsvall, Sweden. Both gentle high consistency and severe low consistency post-refining were performed. High consistency post-refining, at high energy input, gave freeness levels below 70 ml and still preserved the fibre length. These fibres were characterised by a very high flexibility giving sheets with a tensile index as high as 64 kNm/kg. Long fibres can however cause formation problems on a board machine which in turn can lead to poor surface properties, hence shorter fibres are from that perspective desirable. The low consistency post-refining resulted in a rapid drop in freeness due to fibre cutting. This was achieved at an extremely low specific energy input, which probably preserved most of the original fibre stiffness. In spite of this low energy input it was possible to reach the same Z-strength at a given bulk, as for the high consistency post-refined pulp. This implied that high bulk at certain internal bond strength could be achieved with stiff fibres even though the content of long fibres was low. Energy efficient low consistency post-refining of spruce HTCTMP yields high quality pulp at a total energy input of ~800 kWh/admt and is an interesting process concept for production of pulps intended for paperboard.

  • 17.
    Klinga, Niklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sandberg, C
    Sheet properties of high yield pulps related to different pressing and drying conditions - part IIManuskript (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This paper discusses how sheet properties of different mechanical pulps and chemithermomechanical pulps and their respective long fibre fractions depend on the level of dryness to which the sheets are wet pressed before being dried. This was performed with the aim of evaluating the consolidation and evolution of strength properties with respect to dryness. The results show that the development of strength, i.e. tensile strength and internal bond strength measured as Z-strength, is most pronounced in the dryness interval between 50 and 80% for the long fibre fractions.

  • 18.
    Klinga, Niklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sandberg, Christer
    Paper properties of TMP and CTMP handsheets from spruce, as affected by the press load and temperature during sheet drying2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 4, s. 468-474Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this investigation was to evaluate how physical properties of laboratory sheets, made from different thermomechanical and chemithermomechanical pulps, depend on the pressure and temperature levels during pressing and drying. Sheets were formed from long fibre fractions, defined as the pulp retained on a 50 mesh wire in a Britt Dynamic Drainage Jar, and pressed and dried according to a number of different pressure and temperature settings. The results showed that there were large differences in the sheet properties depending on what type of method was used for pressing and drying. High freeness pulps were more sensitive than low freeness pulps to the methods used for pressing and drying. The results indicate that the difference in sheet properties between ISO and Rapid Kothen sheets may be explained by the fact that ISO sheets are wet pressed only at room temperature, the fibres are then allowed to spring back when pressure is released whereas the fibres in Rapid Kothen sheets are locked in their positions as the sheets are pressed and dried at high temperature until dry.

  • 19.
    Klinga, Niklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sandberg, Christer
    Paper properties of TMP and CTMP handsheets from spruce, as affected by the solids content from pressing2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 4, s. 475-480Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper discusses how the properties of dry handsheets from two different mechanical pulps and one chemithermomechanical pulp and their respective long fibre fractions depend on the level of dryness to which the sheets are pressed at high temperature. Sheets were pressed and dried to different dryness levels at 400 kPa and 93 degrees C in a modified Rapid Kothen dryer. Prior to testing of the physical properties, the sheets were dried without pressure at, room temperature to full dryness and kept in a conditioning room. This was performed with the aim of evaluating the consolidation and development of final strength properties with respect to dryness after a press section in a paper machine.The most interesting finding from these trials was that the increase in density and strength were far from linear with increased press dryness, especially for the long fibre fractions when looking at the Z-strength development. There was a distinct inflection of the curve when the sheets reached a press dryness level of some 50%. The most important dryness interval for internal strength development was found between 50 and 80%.The fact that most paper and board machines press the sheet to only some 50% dryness, before feeding it into the drying section, implies that much of the inherent strength potential of mechanical pulps may be unexploited. Further research on pressing to higher dryness levels will in the future be continued at FSCN at Mid Sweden University.

  • 20.
    Klinga, Niklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sandberg, C
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sheet properties of high yield pulps related to different pressing and drying conditions - part I2005Inngår i: International Mechanical Pulping Conference: IMPC 2005, Oslo, Norway, 7-9 June 2005, Oslo: Pappersindustriens tekniske forening , 2005, s. 344-348Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The objective of this investigation was to evaluate how physical properties of laboratory sheets, made from different thermomechanical and chemithermomechanical pulps, depend on the pressure and temperature levels during pressing and drying. Sheet were formed from long fibre fractions, defined as the pulp retained on a 50 mesh wire in a Britt Dynamic Drainage Jar, and pressed and dried according to a number of different pressure and temperature settings. The results showed that there were large differences in the sheet properties depending on what type of method that were used for pressing and drying. High freeness pulps were more sensitive to the type of method used for pressing and drying than low freeness pulps. The results indicate that the difference in sheet properties between ISO and Rapid Köthen sheets might be explained by the fact that ISO sheets are only wet pressed, the fibres are then allowed to spring back when pressure is released whereas the fibres in Rapid Köthen sheets are locked in their positions as the sheets are pressed and dried till over dry.

  • 21. Lindström, M
    et al.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Högberg, H E
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Synthesis of nucleoside analogs: Meeting abstract2003Inngår i: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2003Konferansepaper (Fagfellevurdert)
  • 22.
    Logenius, Louise
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Agnemo, Roland
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    A study of the formation and elimination of chromophores in wood under mechanical pulping conditions using spectroscopy2010Inngår i: Paperi ja puu - Paper and timber, ISSN 0031-1243, Vol. 92, nr 5, s. 35-39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin sections of wood, i.e., shavings, were used in spectroscopic measurements studying the formation and elimination of chromophores under mechanical pulping conditions. Light absorption coefficients, light scattering coefficients, and brightness were monitored.The method was applied to study how temperature in the absence of mechanical energy affects wood brightness. An increase in absorption coefficient at 420 nm indicates formation of ortho-quinone structures. By applying mechanical pulp processing conditions, the light absorption coefficient increased in the 400-500-nm wavelength region, probably due to the formation of chromophores in the lignin. Comparison of heat treated wood shavings with mechanical pulps indicated that additional chromophores were created during the mechanical pulping processes.The method was also used in studying how high-temperature hydrogen peroxide bleaching of the wood shavings affects the light absorption coefficients. The light absorption spectra reveal information about chromophore elimination in wood chemical components during hydrogen peroxide bleaching at slightly pressurized conditions. This is relevant to processes, such as the alkaline peroxide mechanical pulp process, in which the wood chips are impregnated with bleaching chemicals before refining. The easy penetration of chemicals into the wood shavings ensures rapid and even distribution of the treatment chemicals. A change in light absorption coefficient at shorter wavelengths (400-500 nm) was observed.

  • 23.
    Logenius, Louise
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Agnemo, Roland
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    High temperature bleaching of mechanical pulps from spruce2005Inngår i: Proceedings, International Mechanical Pulping Conference, 7-9 June, 2005, Oslo, Norway, 2005, s. 80-84Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A laboratory method was developed, which facilitates to investigate how the temperature profile during a TMP-process including a bleaching stage influences pulp brightness. Thin shavings are prepared by slicing a fresh and frozen block of wood with a microtome. The shavings are rapidly dried in an air-stream at room temperature and the optical properties are measured in an Elrepho instrument. After that the shavings are placed in a stainless steel container that can be pressurized with steam, where the temperature profile in a TMP-process or a bleach plant can be simulated. Addition of bleaching chemicals can be done during the simulation. The optical properties are measured and can be compared to those of the same shaving before treatments. The temperature profile in a TMP-process has a large impact on the optical properties of the pulp. Many studies have been done to show how brightness is affected, when temperature/pressure in TMP processes are varied. However, pilot-scale or full scale-trials can often be performed only under certain limitations. With this new method it is easy to simulate different processing conditions and measure the kinetics of the brightness change on a shaving sample before and after treatments. To get as high final brightness as possible it is necessary to limit the brightness reduction as much as possible in manufacturing of the unbleached pulp.

  • 24.
    Logenius, Louise
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Agnemo, Roland
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    High-Temperature Bleaching of Mechanical Pulps from SpruceManuskript (Annet vitenskapelig)
    Abstract [en]

    High-temperature (HT)-peroxide bleaching of a thermomechanical pulp made of Norwegian spruce was investigated; to that end, one-stage reference bleaching at 70°C and one- and two-stage bleaching at 105°C at different total alkali charges (TAs) using a wing defibrator as a mixer were performed. Two-stage HT peroxide bleaching produces a brighter pulp than one-stage HT peroxide bleaching does. The TA should be kept low (10�15 kg/t) and the total alkali/peroxide ratio should be low in the first stage to minimize the COD load and obtain higher residual peroxide. Increased TA does not improve brightness. The bleaching time in HT bleaching at 105°C can be short, since the maximum brightness is reached after only 2.5 min.Preimpregnation of the pulp with hydrogen peroxide before a two-stage alkali addition can produce a pulp with a brightness and residual peroxide comparable to those obtained in conventional one-stage peroxide bleaching at the same hydrogen peroxide charge and at a low TA. The COD load was, however, higher than in conventional bleaching

  • 25.
    Logenius, Louise
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Agnemo, Roland
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    High-Temperature Bleaching of Mechanical Pulps from Spruce2007Inngår i: Proceedings. Internationl mechanical pulping conference 6-9 May, 2007, Minneapolis, MN, USA, TAPPI Press, 2007, Vol. 2, s. 580-587Konferansepaper (Fagfellevurdert)
    Abstract [en]

    High-temperature (HT)-peroxide bleaching of a thermomechanical pulp made of Norwegian spruce was investigated; to that end, one-stage reference bleaching at 70°C and one- and two-stage bleaching at 105°C at different total alkali charges (TAs) using a wing defibrator as a mixer were performed. Two-stage HT peroxide bleaching produces a brighter pulp than one-stage HT peroxide bleaching does. The TA should be kept low (10�15 kg/t) and the total alkali/peroxide ratio should be low in the first stage to minimize the COD load and obtain higher residual peroxide. Increased TA does not improve brightness. The bleaching time in HT bleaching at 105°C can be short, since the maximum brightness is reached after only 2.5 min. Preimpregnation of the pulp with hydrogen peroxide before a two-stage alkali addition can produce a pulp with a brightness and residual peroxide comparable to those obtained in conventional one-stage peroxide bleaching at the same hydrogen peroxide charge and at a low TA. The COD load was, however, higher than in conventional bleaching.

  • 26.
    Logenius, Louise
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Angemo, Roland
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    High temperature Peroxide Bleaching of TMP from Spruce2006Inngår i: 5th Fundamental Mechanical Pulping Reasearch Seminar, 31 May- 1 June, 2006, Trondheim, Norway, 2006Konferansepaper (Annet vitenskapelig)
  • 27.
    Logenius, Louise
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Agnemo, Roland
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Impact of temperature profile on the brightness of spruce wood2004Inngår i: 4th Fundamental Mechanical Pulping Research Seminar, 7-8 June, 2004, Stockholm, Sweden, 2004Konferansepaper (Annet vitenskapelig)
  • 28.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Gradin, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Isaksson, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Acoustic emission monitoring to evaluate the z-direction and in-plane strength properties of TMP reject fractionManuskript (Annet vitenskapelig)
  • 29.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hoglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Consolidation of fibre-fibre bonds in TMP and CTMP based papers2014Inngår i: Paper Technology, ISSN 0958-6024, Vol. 55, nr 3, s. 6-10Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    TMP and CTMP fibres are viscoelastic materials, which behave very differently at different temperatures and loading rates, should also be considered in papermaking. The positive effects of increased web temperature on dewatering and web consolidation (sheet strength) in pressing and drying of TMP/CTMP based papers have been known for some time. However, the effects of dry content during such conditions are less closely investigated. In this paper the effect of dry content on fibre-fibre bonds in consolidation of paper webs during press drying at high temperature is discussed. It is shown that the final paper strength is especially positively affected when a Z-directionalpressure is applied in the dryness range 50-75%.

  • 30.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Consolidation of fibre-fibre bonds in TMP and CTMP based papers2011Inngår i: PROCEEDING OF INTERNATIONAL MECHANICAL PULPING CONFERENCE 2011, 2011, s. 448-453Konferansepaper (Fagfellevurdert)
    Abstract [en]

    TMP and CTMP fibres are viscoelastic materials, which behave very differently at different temperatures and loading rates, which should to be considered also in papermaking. The positive effects of increased web temperature on dewatering and web consolidation (sheet strength) in pressing and drying of TMP/CTMP based papers are well known since a long time. However, the effects of dry content during such conditions are less closely investigated. In this paper the effect of dry content on fibre-fibre bonds in consolidation of paper webs during press drying at high temperature is discussed. It is shown that the final paper strength is especially positively affected when a Z-directional pressure is applied in the dryness range 50%similar to 75 %.

  • 31.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Irreversible long fibre collapse at high temperature refining in a TMP system: Effects on fibre and surface properties2009Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, nr 1, s. 19-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effects on fibre and sheet properties of preheating to temperature well above the softening temperature of lignin in refining of spruce TMP reject were evaluated. This study indicates that an improved surface smoothness can be attained on TMP-based wood-containing papers through high-temperature reject refining. Under these conditions the degree of irreversible fibre collapse increased. Results from tests of the fibre-wall, fibre surface characteristics, pulp yield and sheet brightness show only marginal differences at high temperatures compared to standard reject refining. Experiments in which laboratory sheets were moistened showed that a high degree of irreversible fibre collapse correlates with surface smoothness.

  • 32.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Irreversible long fibre collapse at high temperature reject refining in a TMP system: Effects on fibre and surface properties2005Inngår i: Proceedings International Mechanical Pulping Conference Oslo 2005, 2005, s. 163-168Konferansepaper (Annet vitenskapelig)
  • 33.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Irreversible long fibre collapse at high temperure reject refining in at TMP system - Initial studies.2003Inngår i: Proceedings from IMPC 2003, Quebec city, 2003Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Irreversible Long Fibre Collapse at High Temperature Reject Refining in a TMP System

  • 34.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Moisture-Induced Surface Roughness in TMP Sheets.2007Inngår i: International Mechanical Pulping Conference 2007, TAPPI, TAPPI Press, 2007, Vol. 2, s. 718-729Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Favourable surface properties can be attained in softwood thermomechanical pulp (TMP)-based sheets, if most of the thick-walled long fibres are collapsed. Provided this can be done, a large amount of TMP can be used in highquality wood-containing papers, i.e., LWC or SC grades, without serious printability problems. It is known that the degree of fibre collapse during refining under standard TMP conditions is strongly related to the fibre wall thickness. However, the thickness of the thickest fibre walls cannot easily be changed by peeling actions in refining under standard TMP conditions in the CSF range of interest for news and magazine grades. Therefore, refining conditions obviously must be changed to enable the proper collapse of these fibres. Earlier studies (Norgren and Höglund, IMPC 2003 and 2005) have demonstrated that thick-walled fibres are more easily collapsed by reject refining after preheating to temperatures well above the softening temperature of lignin, i.e., high temperature conditions, than under standard conditions. If water is applied to the surface of a TMP-based paper during coating or printing, some fibres "decollapse", i.e., revert to their original shape. Earlier studies have demonstrated that decollapse is affected by both fibre wall thickness and fibre circumference (Norman and Höglund, IMPC 2003 and Norgren and Höglund, IMPC 2003). The present study evaluates the effects of moisture on sheets made of different Bauer-McNett (BMN) fractions, both individually and in combination. The pulps investigated are spruce TMP reject pulp made under reference and hightemperature conditions. The smoothness of laboratory sheets made of the BMN fractions were measured with PPS and with an optical scanning instrument, after moistening the sheets in environments of different relative humidities, i.e., 50-98%, to a sheet moisture content (MC) in approximately the 5-25% range. This was done to gain a better fundamental understanding of the conditions resulting in irreversible fibre collapse and of how combinations of types of fibres with different bonding abilities influenced the surface roughness. It is well known that the coarse, stiff, long fibres from the BMN >16 fractions cause surface roughness in dry sheets. However, this study indicates that the shapes of these fibres remain relatively unchanged when moisture diffuses into the sheet structure, i.e., the degree of decollapse is low. It also indicates that sheets including both coarse fibres and fibres from the middle fractions display the highest surface roughness values at a high MC. The fibres from the middle fraction rise easily, causing the greatest change in surface roughness when moisture is added to the sheet. The trials also indicate that fines contribute somewhat to increased surface roughness; when the degree of bonding in the sheet structure is increased, there is a risk that the whole structure or fibre flocks, instead of the individual fibres, may swell.

  • 35.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Moisture-induced surface roughness in TMP sheets2008Inngår i: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 34, nr 3, s. 139-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study evaluates effects of moisture on sheet properties made different Bauer-McNett fractions from TMP, both individually and in combinations. It is well known that the coarse, stiff, long fibre fractions cause surface roughness in dry sheets. However, this study indicates that these fibres remain relatively unchanged when moisture diffuses into the sheet structure, i.e., the degree of decollapse is low. The fibres from the middle fraction rise easily, causing the greatest change in surface roughness when moisture is added to the sheet. Sheets including both coarse fibres and fibres from the middle fractions display the highest surface roughness values at a high moisture content. The trials also indicate that fines contribute to increased surface roughness: when the degree of bonding in the sheet structure is increased, there is a risk that the whole structure or the flocks, instead of the individual fibres, may swell.

  • 36.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bäck, R
    Irreversible long fibre collapse at high temperature TMP reject refining - initial studies2004Inngår i: Pulp & paper Canada, ISSN 0316-4004, Vol. 105, nr 7, s. 47-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effects of preheating temperature on energy consumption,fibre collapse and pulp quality in refining of spruce TMP reject material were studied. At preheating to temperatures well above the softening temperature of lignin thick-walled fibres were collapsed to a higher degree. Shives and fibres in the BMN +10 fraction were efficiently reduced. An increase in sheet density was obtained. Energy consumption was reduced, at a certain freeness level. This study indicates that an improved surface smoothness can be achieved as result of high temperature reject refining.

  • 37.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Pettersson, Gunilla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    High strength papers from high yield pulps2014Inngår i: International Mechanical Pulping Conference, IMPC 2014, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The positive effects changing the present standard conditions regarding temperature and moisture content during pressing and drying in papermaking of high yield pulp furnishes, such as those from TMP and CTMP, has previously been reported in a series of studies at Mid Sweden University. In the current study, the effects of fibre surface modification by starch/CMC at press-drying conditions have been investigated. It is shown how the strength properties of sheets from HTCTMP, manufactured at very low electric energy consumption (approximately 600 kWh/ton), can be radically improved by several hundred percent at optimum papermaking conditions.

  • 38.
    Norgren, Sven
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Pettersson, Gunilla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Strong paper from spruce CTMP - Part II: Effect of pressing at nip press temperatures above the lignin softening temperature2018Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, nr 1, s. 142-149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective of the current study was to demonstrate that it is possible to enhance strength properties of sheets from spruce HT-CTMP and CTMP furnishes up to the same level as is common on sheets from softwood kraft pulps by changing conditions in papermaking. To achieve that, sheets of spruce HT-CTMP and CTMP were consolidated at densities close to that of the reference bleach kraft pulp by pressing at press nip temperatures well above the tack and softening temperatures of lignin. On sheets from spruce CTMP (CSF 420 ml), where the fibers were surface treated with cationic starch, it was possible to reach tensile index at the same level as on sheets from the untreated reference kraft pulp. The compression strength (SCT) of CTMP and HT-CTMP sheets, which were achieved at the highest press nip temperature (200 °C) in the study, was equal to or higher than that of the reference kraft pulp sheets. The results show that there is a great yet unexploited potential in papermaking from spruce HT-CTMP and CTMP furnishes, which could be utilized in manufacturing of products where very high requirements upon strength is demanded. 

  • 39. Norman, Fredrik
    et al.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Moisture-induced surface roughness in TMP-based paper - The influence of fiber cross-section dimensions: IMPC 20032003Konferansepaper (Annet vitenskapelig)
  • 40. Nygren, Olle
    et al.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Roland, Bäck
    On characterization of mechanical and chemimechanical pulps2003Inngår i: International Mechanical Pulping conference, Quebec, Que, Canada, 2-5 June 2003,, Montreal: Pulp and Paper Technical Association of Canada , 2003, s. 486-Konferansepaper (Fagfellevurdert)
  • 41.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Peng, F.
    Stora Enso, Karlstad.
    Granfeldt, T.
    Valmet, Sundsbruk.
    Bergström, J.
    SCA Östrand, Timrå.
    Joelsson, T.
    MoRe Research, Domsjö.
    Upgrading the strength properties of sheets from hardwood high yield pulps2018Inngår i: Pan Pacific Fibre Value Chain Conference 2018, Proceedings, Appita Inc. , 2018, s. 142-147Konferansepaper (Fagfellevurdert)
  • 42.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Sjöberg, Jessica
    SCA Östrand Mill, SE-86181 Timra, Sweden.
    Peng, Frank
    Stora Enso Res Ctr, SE-65637 Karlstad, Sweden.
    Hallgren, Hans
    Stora Enso Res Ctr, SE-65637 Karlstad, Sweden.
    Moberg, Anders
    Stora Enso Res Ctr, SE-65637 Karlstad, Sweden.
    Ljungqvist, Carl-Henrik
    Stora Enso Res Ctr, SE-65637 Karlstad, Sweden.
    Bergström, Jörgen
    SCA Östrand Mill, SE-86181 Timra, Sweden.
    Solberg, Daniel
    SCA Östrand Mill, SE-86181 Timra, Sweden.
    Strong and bulky paperboard sheets from surface modified CTMP, manufactured at low energy2015Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 2, s. 318-324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A description is given regarding methods used to manufacture strong and bulky sheets from furnishes based on a broad range of surface modified CTMP qualities. Starch and CMC are adsorbed on the fibre surfaces using a multilayer or a MIX concept. It is shown that both the in-plane and out-of-plane strength for the CTMP based sheets after such surface treatment can be more than doubled at a maintained density. This can be utilized to improve bending stiffness or to reduce the basis weight in multi-ply paperboards.

  • 43.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Sjöberg, J. C.
    SCA Östrand Pulp Mill, SE-861 81 Timrå, Sweden .
    Peng, F.
    Stora Enso Research Centre, SE-656 37 Karlstad, Sweden.
    Bergström, J.
    SCA Östrand Pulp Mill, SE-861 81 Timrå, Sweden .
    Solberg, D.
    SCA Östrand Pulp Mill, SE-861 81 Timrå, Sweden .
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hallgren, H.
    Stora Enso Research Centre, SE-656 37 Karlstad, Sweden.
    Moberg, A.
    Stora Enso Research Centre, SE-656 37 Karlstad, Sweden.
    Ljungqvist, C. -H
    Stora Enso Research Centre, SE-656 37 Karlstad, Sweden.
    Strong and bulky paperboard plies from low energy CTMP2014Inngår i: International Mechanical Pulping Conference, IMPC 2014, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A description is given regarding methods used to manufacture strong and bulky sheets from furnishes based on a broad range of surface modified CTMP qualities. Starch and CMC are adsorbed on the fibre surfaces using a multilayer or a MIX concept. It is shown that both the in-plane and out-of-plane strength for the CTMP based sheets after such surface treatment can be more than doubled at a maintained density. This can be utilized to improve bending stiffness or to reduce the basis weight in multi-ply paperboards.

  • 44.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Wågberg, Lars
    Formation of polyelectrolyte multilayers of polyvinylamine/CMC and cationic starch/CMC on birch CTMP and their influence on paper strengthManuskript (preprint) (Annet vitenskapelig)
  • 45.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Wågberg, Lars
    KTH, Stockholm.
    The use of polyelectrolyte multilayers of cationic starch and CMC to enhance strength properties of papers formed from mixtures of unbleached chemical pulp and CTMP: Part I2006Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, nr 1, s. 115-121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction of alternating multilayers of cationic potato starch and anionic carboxymethylcellulose(CMC) was investigated in two parts. In the first part, stagnation point adsorption reflectometry (SPAR) showed that the chosen chemicals formed polyelectrolyte multilayers (PEM)upon adsorption to the silicon oxide surface. This was in accordance with earlier work. The chosen polyelectrolytes adsorbed to similar extents on the silicon oxide surface and recharged the surface enough to allow for adsorption of a consecutive layer. In the second part, the multilayer concept was tested on 80/20,20/80% of total in mixture of mixed spruce CTMP and bleached chemical pulp in order to enhance the sheet strength properties of a typical packaging board furnish.. The multilayers yielded a significant improvement in Scott Bond values and tensile index and a marginal improvement in tensile stiffness index. The Scott Bond values were improved more than 150% for papers prepared from a furnish consisting of 80% spruce CTMP and 20% chemical pulp. Polyelectrolyte multilayers treatment also led to a slight densification of the sheets, but the polyelectrolyte multilayers treatment resulted in a more favourable density/strength relationship than that achieved with a change in the amount of chemical pulp.

  • 46.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Wågberg, Lars
    KTH.
    The use of polyelectrolyte multilayers of cationic starch and CMC to enhance strength properties of papers formed from mixtures of unbleached chemical pulp and CTMP-II: Part II: Influnence of addition strategy, fibre treatment and fibre type2006Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, nr 1, s. 122-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polyelectrolyte multilayers (PEM) consisting of cationic starch and anionic carboxymethylcellulose (CMC) have been applied to different pulp fibres in order to enhance the out-of-plane sheet strength properties of a typical packaging board furnish. An unbleached softwood chemical pulp was treated with multilayers consisting of two layers of cationic starch and one layer of CMC, and then mixed with different mechanical and chemimechanical pulps. Hand sheets were prepared with the aid of the Rapid Köthen sheet former from stocks consisting of 20% treated chemical pulp and 80% mechanical or chemimechanical pulp, which was either PGW from spruce, HT-CTMP from spruce or birch, or a standard spruce CTMP. Multilayer treatment significantly improved Scott Bond values and in some cases improved the tensile index, with the achieved effects being significantly larger than the effects of applying starch alone. Positive effects were obtained by treating only 20% of the furnish, showing a very high efficiency of the adsorbed multilayers. Compared to earlier work, one important finding was that the PEM treatment should preferably be applied only to the chemical pulp and not on the entire stock. It was possible to increase the out-of-plane strength properties, measured as Scott Bond values, with just a very small increase in density of the sheets. Multilayer treatment of the chemical pulp improved the joint strength between the fibres while maintaining the high bulk of the sheets prepared from the stiff mechanical and chemimechanical fibres.

  • 47.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Strong paper from spruce CTMP2016Inngår i: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, s. 229-233Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study was carried out on sheets from spruce CTMP fibers, which are surface treated with a mix of cationic starch and CMC and blended with 20% bleach softwood chemical pulp fibers before handsheets were prepared in a Rapid Kothen sheet former, where the sheets were dried to 40-55% d.c. The sheets were pressed in a hot press nip in a pilot machine with adjustable pressure and heat. Both low and high nip pressure were used in combination with two different nip temperatures, 80 °C and 100 °C, to achieve sheets in a broad range of densities. The results show that remarkable improvements are possible, both in terms of tensile index (up to 85 kNm/kg) and compression strength, SCT, (up to 38kNm/kg) on the CTMP-based sheets under optimal conditions at papermaking, i.e. consolidate the sheet structure in a press nip at evaluated temperatures. It is evident from the current study that there is an as of yet unexploited potential in modifying the conditions of papermaking from spruce CTMP furnishes, which can be utilized for the manufacturing of papers with high requirements on strength and stiffness, e.g. packaging papers.

  • 48.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Strong paper from spruce CTMP - Part I2017Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 1, s. 54-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study was carried out on sheets from spruce CTMP fibers, which are surface treated with a mix of cationic starch and CMC and blended with 20% bleach softwood chemical pulp fibers before handsheets were prepared in a Rapid Köthen sheet former, where the sheets were dried to 40-55% d.c. The sheets were pressed in a hot press nip in a pilot machine with adjustable pressure and heat. Both low and high nip pressure were used in combination with two different nip temperatures, 80°C and 100°C, to achieve sheets in a broad range of densities. The results show that remarkable improvements are possible, both in terms of tensile index (up to 85 kNm/kg) and compression strength, SCT, (up to 38 kNm/kg) on the CTMP-based sheets under optimal conditions at papermaking, i.e. consolidate the sheet structure in a press nip at evaluated temperatures. It is evident from the current study that there is an as of yet unexploited potential in modifying the conditions of papermaking from spruce CTMP furnishes, which can be utilized for the manufacturing of papers with high requirements on strength and stiffness, e.g. packaging papers.

  • 49.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Low energy CTMP in strong and bulky paperboard plies2016Inngår i: Paper Conference and Trade Show, PaperCon 2016, TAPPI Press, 2016, Vol. 1, s. 556-564Konferansepaper (Fagfellevurdert)
  • 50.
    Pettersson, Gunilla
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sjöberg, Jessica
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Wågberg, Lars
    Höglund, Hans
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Averheim, Andreas
    Luleå University of Technology.
    Increased joint-forming ability of ductile kraft pulp fibres by polyelectrolyte multilayer treatment-Influence of refining and drying strategies2007Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 2, s. 228-235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study a sack paper furnish was used. It consisted of a high-consistency kraft pulp refined in either an atmospheric pressure or a pressurized system. The pulps were subsequently low-consistency refined in an Escher-Wyss laboratory refiner to 17.5-20.5 SR. Ordinary ISO sheets and freely dried sheets were manufactured from these pulp samples to serve as reference sheets. The laboratory sheets made of pulp from the pressurized system had a higher strain at break and tensile energy adsorption index but a lower tensile index than sheets made of pulp from a conventional atmospheric highconsistency refiner. These sheets were subject to a polyelectrolyte multilayer treatment to increase the interaction between the fibres, thus enhancing the paper strength properties. The polyelectrolyte multilayers (PEM) were applied by sequentially treating fibres from an unbleached kraft pulp for sack paper production with cationic starch and anionic carboxymethyl cellulose. The multilayer treatment was only applied to 50% of the stock and both ordinary ISO sheets and freely dried sheets were prepared with one and three layers of polyelectrolyte. Evaluation of the strength properties of the sheets showed that the addition of only one layer of starch increased strain at break, tensile index, tensile energy adsorption index, and out-of-plane properties measured as Scott-bond values. Using the multilayer technique created large increases in Scott-bond, a measure of the internal bonding of the sheets. The achieved effects were significantly larger than those usually achieved by applying starch alone to enhance the out-of plane strength properties. Also, the density increased considerably when the third layer was applied, for both ISO and freely dried sheets, though the tensile strength was enhanced significantly only in the freely dried sheets.

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