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  • 151.
    Danielsson, Sverker
    RISE, Innventia.
    Sorption and desorption of black liquor xylan onto cellulose fibers2014In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 48, no 9-10, p. 819-823Article in journal (Refereed)
    Abstract [en]

    The potential of xylan as a polymer in different new materials is large and not yet utilized. The availability in kraft pulp mills is large as the polymeric xylan dissolved in process liquors corresponds to up to 160 kg/adt and is today burnt to recover energy. A pre-requisite for using black liquor xylan in high-value products is to purify it from inorganic material and lignin in a technically effective and economical feasible way. This study combines two known properties of xylan: its affinity to cellulose and its solubility in alkali. The aim is to design an efficient separation process to produce black liquor xylan of high purity. A very pure xylan was reached with as low lignin contents as 1%. The hydroxide ion concentration was varied in the sorption step and it was found that an increase in hydroxide ion concentration resulted in a decreased amount of isolated xylan, decreased degree of substitution of uronic acids, but no effect on the lignin content and ash content was seen.

  • 152.
    Danielsson, Sverker
    et al.
    RISE, Innventia.
    Holm, Richard
    RISE, Innventia.
    Öhman, Fredrik
    Lipnizki, Frank
    A novel approach for applied membrane filtration on processing flows2012Conference paper (Refereed)
  • 153.
    De San Pio, Ignacio
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Papermaking and Packaging.
    Johansson, Klas G.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Papermaking and Packaging.
    Krochak, Paul
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Papermaking and Packaging.
    Filler co-flocculation with MFC: Novel predictive method2019In: PaperCon 2019: Proceedings, TAPPI Press, 2019, article id PA2-PF1.2Conference paper (Other academic)
    Abstract [en]

    Research has been undertaken in which a combination of different techniques was utilised to compare pre-flocculation (flocculant added to the filler prior to its addition to the pulp) with pre-mixing strategies, also called co-flocculation (chemicals added to a mixture of cellulose microfibrils (CMF) and filler. The pulp used was a mixture of 80% hardwood kraft pulp and 20% softwood kraft pulp. The filler was ground calcium carbonate (GCC), while the chemicals used included cationic polyacrylamide (CPAM), silica, bentonite, anionic PAM (APAM), cationic starch and CMF. Using the focused beam reflectance method (FBRM) enabled an in-depth and quick study of the filler floc behaviour at different dosages and mixing conditions, demonstrating that it was a very good tool as a pre-screening for different treatment alternatives. Clear differences in behaviour between different pre-flocculation and pre-mixing strategies were observed. For the pre-mixing strategy, the most promising results were achieved with CPAM plus bentonite and cationic starch systems. Although dewatering was negatively affected with pre-mixing, the mechanical properties were clearly improved. Flocs obtained with PCAM/bentonite had a similar resistance with both strategies, while cationic starch was clearly more advantageous when using the pre-mixing strategy.

  • 154. De San Pio, Ignacio
    et al.
    Simons, Andrew
    RISE Research Institutes of Sweden, Built Environment, Energy and Resources.
    Delgado, Luis Fernando
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Process Water Management for Sustainable Papermaking2022Conference paper (Refereed)
    Abstract [en]

    Some of the challenges in papermaking have been the same for many years, however the demands from the market are increasing continuously and, together with them, the challenges for the paper mills. We consider it is the time to put a lot of efforts together to help papermaking industry to comply with these new demands on a cost-effective way. When it comes to the wet-end chemistry and stock preparation this is a clear and actual challenge. Many developments have been done in developing green chemicals with higher efficiency, machine suppliers are improving the efficiency of each unit, fiber recovery and water cleaning technologies are also under continuous improvement, but the degree of implementation of those advances is still limited. From our perspective, a mindset change is needed, where all those developments are combined to improve the product properties and the process efficiency. Process waters have a very important role to play in that, and in this presentation, we will demonstrate the link and importance that keeping the process water components under control can give to the process. Those improvements were evaluated at lab scale, demonstrated at pilot scale and then implemented at mill level. We will show how the performance of the process chemicals is affected by the process water components, and the impact on the product quality. We will also describe the methods used to understand and evaluate those impacts and describe in a full-scale test how improving the process waters lead to energy savings and the possibility to improve the product performance. The designed methodology can be of use for: - Chemical suppliers, that need to evaluate and demonstrate the performance on challenging processes, such as closed water loop mills. - Companies looking to save water and energy, identifying the costs related to their actual water management and therefore the benefits to implement the right technologies. - Water cleaning technology suppliers that are nowadays not implemented in paper mills, that would be able to demonstrate the removal of the right contaminants and the potential savings that this technology can give to the specific mill. - Paper mills with challenges due to changes in their incoming water quality, or when there are increasing demands from the market that require adaptation of the process chemistry, unlocking possibilities for further development. 

  • 155.
    Djafari Petroudy, Seyed Rahman
    et al.
    Shahid Beheshti University, Iran.
    Ghasemian, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Sari University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of xylan on the fibrillation efficiency of DED bleached soda bagasse pulp and on nanopaper characteristics2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 385-395Article in journal (Refereed)
    Abstract [en]

    Xylan is the second most abundant polysaccharide and the most abundant hemicellulose component of soda bagasse pulp. In this study, bleached soda bagasse pulp (SB) and bleached bagasse dissolving pulp (DB) with varying amounts of xylan were fibrillated with a homogenization process. The produced fibrillated materials were used for making nanopaper structures. The surface, physical, mechanical and optical properties of the nanopaper were measured, and the effect of xylan was assessed. Laser profilometry (LP) and field emission scanning electron microscopy were applied to study the degree of the fibrillation. The pulp having the highest xylan content, SB, showed the highest yield of cellulose nanofibrils. Nanopaper produced from SB had a more consolidated structure than that produced from DB. Additionally, SB nanopaper yielded higher tensile strength, lower LP roughness, a higher barrier against oxygen and lower opacity. These results indicate a higher degree of fibrillation of the SB pulp compared to the DB pulp. Hence, the positive effect of xylan for facilitating the fibrillation of the starting pulp fibers was demonstrated.

  • 156.
    Djafari Petroudy, Seyed Rahman
    et al.
    NTNU Norwegian University of Science and Technology, Norway; Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Effects of bagasse microfibrillated cellulose and cationic polyacrylamide on key properties of bagasse paper2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 99, p. 311-318Article in journal (Refereed)
    Abstract [en]

    This study explores the benefits of using bagasse microfibrillated cellulose (MFC) in bagasse paper. Two different types of MFC were produced from DED bleached soda bagasse pulp. The MFC was added to soda bagasse pulp furnishes in different amounts. Cationic polyacrylamide (C-PAM) was selected as retention aid. The results show that addition of MFC increased the strength of paper as expected. Interestingly, 1% MFC in combination with 0.1% C-PAM yielded similar drainage time as the reference pulp, which did not contain MFC. In addition, the samples containing 1% MFC and 0.1% C-PAM yielded (i) a significant increment of the tensile index, (ii) a minor decrease of opacity and (iii) preserved Gurley porosity. Hence, this study proves that small fractions of MFC in combination with adequate retention aids can have positive effects with respect to paper properties, which is most interesting from an industrial point of view.

  • 157. Djafari Petroudy, S.R.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, A.
    Resalati, H.
    Gregersen, Ø.W.
    Oriented nanopaper (ONP) made of bagasse nanofibrils2012Conference paper (Refereed)
  • 158.
    Dominic, Chris
    RISE, Innventia.
    Packaging logistics performance and how to evaluate the packaging performance by applying the tool packaperforma2010In: 17th IAPRI World Conference on Packaging 2010, 2010, p. 245-250Conference paper (Refereed)
    Abstract [en]

    Packaperforma is a tool developed in order to increase the efficiency, effectiveness and differentiation in the future design of packaging systems. The tool is based on the theory Packaging Logistics Performance. Packaperforma is a further development of Packaging Scorecard and it could be utilized by packaging designers and supply chain managers to see the functions of the packaging system in the logistics processes. This means that the gap between packaging decisions and logistics decisions can be mitigated, as it can share the downstream information with the upstream and the designers. Packaperforma is used to conduct comparative studies in multiple Supply-Demand Chains. A study as such increases the quantity of data in the Packaperforma database that could be used to indicate the performances of the packaging, the agent and the Supply Demand Chains. The paper presents a study on Packaging Logistics Performance, how to evaluate packaging performance; how to collect feedback information from different agents and efficiently solve packaging related problem. Further the paper describes a web system based tool, packaging performance indicators and packaging performance database.

  • 159.
    Dong, F.
    et al.
    RISE, Innventia.
    Olsson, Anne-Mari
    RISE, Innventia.
    Salmen, Lennart
    RISE, Innventia.
    Fibre morphological effects on mechano-sorptive creep2010In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 44, no 3, p. 475-483Article in journal (Refereed)
    Abstract [en]

    The increased creep rate of paper under load during moisture cycling conditions as compared to that at high constant humidity is a problem in the use of packaging materials. In order to investigate the influence of morphological factors of the fibres on the occurrence and magnitude of this phenomenon, i.e. the occurrence of mechano-sorptive creep, studies on wood fibres isolated from different parts of spruce wood were performed. Thus, creep properties were studied on earlywood and latewood fibres from both juvenile wood and mature wood. In general, latewood fibres showed a higher degree of mechano-sorptive creep than earlywood fibres, and mature wood showed a higher degree of mechano-sorptive creep than juvenile fibres. The difference in mechano-sorptive creep rate between different fibres was shown to be correlated to the differences in fibril angle. The smaller the fibril angle the higher was the mechano-sorptive creep ratio. It was suggested that at fibril angles approaching 45° wood fibres do not exhibit mechano-sorptive creep.

  • 160.
    Drotz, Mattias
    RISE - Research Institutes of Sweden, Bioeconomy.
    Influence of pulp and process parameters on the strength properties of low grammage laboratory2017In: Tissue World Milan 2017: Proceedings, 2017, article id 23Conference paper (Other academic)
    Abstract [en]

    Toilet, towel and facial products have important properties, for example, softness, absorption, wet strength and strength. Research has been undertaken to investigate the influence of pulp and process parameters on the strength properties of low grammage sheets. Various pulps were investigated and their fibre length, fibre width, fines and coarseness were determined. Based on analysis, it has been concluded that fibre length is essential for tear related properties. Compared with a softwood fibre, a crack propagates faster in a hardwood sheet. Although refining improved the tear related properties to a certain extent, it had a negative impact on the dewatering properties and density. This PowerPoint presentation incorporates some stand-alone graphically presented data with minimal textural interpretation.

  • 161.
    Drotz, Mattias
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Sjöstedt, Anna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Verma, Manish
    Swedish Exergy AB, Sweden.
    Verma, Prem
    Swedish Exergy AB, Sweden.
    A laboratory investigation of Superheated Steam Dried pulps2022In: TAPPICon Conference 2022, TAPPI Press , 2022Conference paper (Refereed)
    Abstract [en]

    Superheated steam drying is used commercially for lumber, coal, peat, sludges, but has limited installations towards market pulp applications. The technology has the potential for higher drying rates, lower energy consumption, better product quality, and safe operation. In this investigation, a superheated steam dryer (EXERGYPSSD®) was used for evaluation of wet pulp samples collected from pulp mills for comparison with conventional drying techniques. The evaluation of the superheated steam dried pulps indicated that there are potential quality benefits with the technology. Improvements of bulk and absorption capacity was achieved, but more laboratory, and pilot tests are needed to optimize the technology even more regarding pressure, temperature, and residence time in the dryer.

  • 162.
    Duker, Elisabeth
    et al.
    RISE, STFI-Packforsk.
    Ankertors, Mikael
    RISE, STFI-Packforsk.
    Lindström, Tom
    RISE, STFI-Packforsk.
    Glad-Nordmark, Gunnel
    RISE, STFI-Packforsk.
    The use of CMC as a dry strength agent: The interplay between CMC attachment and drying2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 1, p. 65-71Article in journal (Refereed)
    Abstract [en]

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

  • 163.
    Duker, Elisabeth
    et al.
    RISE, STFI-Packforsk.
    Lindström, Tom
    RISE, STFI-Packforsk.
    On the mechanisms behind the ability of CMC to enhance paper strength2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 1, p. 57-64Article in journal (Refereed)
    Abstract [en]

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

  • 164. Ek, Monica
    et al.
    Chirat, Christine
    Li, Dongfang
    Iversen, Tommy
    Malmström, Eva
    Norström, Emelie
    Sixta, Herbert
    WOBAMA: wood based materials2014Conference paper (Refereed)
  • 165. Enberg, S.
    et al.
    Rundlöf, M.
    Paulsson, M.
    Johnsen, I.A.
    Axelsson, P
    The influence of process conditions during pulp storage on the optical properties of Norway spruce high-yield pulps2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, p. 203-210Article in journal (Refereed)
  • 166.
    Enberg, Sofia
    et al.
    Norske Skog Saugbrugs, Norway; Mid Sweden University, Sweden.
    Rundlöf, Mats
    Mid Sweden University, Sweden; Capisco Science and Art, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Sweden; AkzoNobel Pulp and Performance Chemicals, Sweden.
    Axelsson, Patrik
    Norske Skog Saugbrugs, Norway.
    Eriksen, Øyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Engstrand, Per O.
    Mid Sweden University, Sweden.
    Some causes of formation of colour during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 2, no 29, p. 356-366Article in journal (Refereed)
    Abstract [en]

    The discolouration of hydrogen-peroxide bleached Norway spruce mechanical pulp during storage in mill systems was studied and the contributions of process water, iron and dyes were evaluated over the visible spectrum. Washing of the pulp made it less sensitive to storage, possibly due to the removal of extractives, lignin-like substances, iron and pulp fines. Storage in white water gave extensive discolouration with a shoulder in the absorption spectrum at around 550- 650 nm. Most of the colour was associated with pulp fines or filler but some colour was also found in smaller fractions and in the water phase. The addition of ferric ions increased the light absorption coefficient during storage, initially at short wavelengths and then over the whole spectrum, but could not explain the increased absorption at 550-650 nm and could not be the only cause of the darkening in the mill system. A cationic basic violet dye gave a shoulder in the absorption spectrum similar to that in the mill system, but the absorption in this area did not increase during storage. Model calculations indicate that ferric ions together with violet and red dyes could explain a major part, but not all, of the colour observed in the mill system after storage. The darkening not accounted for at longer wavelengths and around 550-650 nm is suggested to be related to fines and fillers including dissolved and colloidal substances associated with these particles.

  • 167.
    Enberg, Sofia
    et al.
    Norske Skog Saugbrugs, Norway; Mid Sweden University, Sweden.
    Rundlöf, Mats
    Mid Sweden University, Sweden; Capisco Science and Art, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Sweden; AkzoNobel Pulp and Performance Chemicals, Sweden.
    Axelsson, Patrik
    Norske Skog Saugbrugs, Norway.
    Eriksen, Øyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Engstrand, Per O.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The influence of process waters on optical properties during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 2, no 29, p. 344-355Article in journal (Refereed)
    Abstract [en]

    To evaluate the causes behind the formation of colour in mill systems, the effect of different process waters on the optical properties of hydrogenperoxide bleached Norway spruce mechanical pulp during storage was studied. The influence of process water type, temperature, time, pulp consistency and pH was evaluated over the visible range of wavelengths. The darkening was more pronounced when pulp was stored in process waters compared to in distilled water. Increased temperature and prolonged storage times increased the darkening as expected, whereas a higher storage consistency gave less darkening than a lower storage consistency (15% compared to 5%). The pH value that gave the lowest brightness reduction and a minimum in Δk460 was found to be 5.5-6.0. Storage of pulp in white water from the paper machine resulted in a broad shoulder in the k spectra indicating colour formation related to the particles in this water. Part of this shoulder in absorption spectra was related to added dyes, but the increase in absorption with time is likely to be caused by some other colour formation. The colour measured as a∗, b∗ showed that the storage changed the colour of the pulp towards red and yellow, and initially more towards red.

  • 168.
    Eriksen, O.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Holmqvist, Claes
    RISE, STFI-Packforsk.
    Mohlin, Ulla-Britt
    RISE, STFI-Packforsk.
    Fibre floc drainage - a possible cause for substantial pressure peaks in low-consistency refiners2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 3, p. 321-326Article in journal (Refereed)
    Abstract [en]

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

  • 169.
    Eriksen, O.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Holmqvist, Claes
    RISE, STFI-Packforsk.
    Mohlin, Ulla-Britt
    RISE, STFI-Packforsk.
    Theoretical outline of the cause for observed cavitation in a low-consistency refiner2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 3, p. 315-320Article in journal (Refereed)
    Abstract [en]

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

  • 170.
    Erlandsson, Johan
    et al.
    KTH Royal institute of technology, sweden.
    Pettersson, Torbjörn
    KTH Royal institute of technology, Sweden.
    Ingverud, Tobias
    KTH Royal institute of technology, Sweden.
    Granberg, Hjalmar
    RISE - Research Institutes of Sweden, Bioeconomy.
    Larsson, Per A.
    KTH Royal institute of technology, Sweden.
    Malkoch, Michael
    KTH Royal institute of technology, Sweden.
    Wågberg, Lars
    KTH Royal institute of technology, Sweden.
    On the mechanism behind freezing-induced chemical crosslinking in ice-templated cellulose nanofibril aerogels2018In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 40, p. 19371-19380Article in journal (Refereed)
    Abstract [en]

    The underlying mechanism related to freezing-induced crosslinking of aldehyde-containing cellulose nanofibrils (CNFs) has been investigated, and the critical parameters behind this process have been identified. The aldehydes introduced by periodate oxidation allows for formation of hemiacetal bonds between the CNFs provided the fibrils are in sufficiently close contact before the water is removed. This is achieved during the freezing process where the cellulose components are initially separated, and the growth of ice crystals forces the CNFs to come into contact in the thin lamellae between the ice crystals. The crosslinked 3-D structure of the CNFs can subsequently be dried under ambient conditions after solvent exchange and still maintain a remarkably low density of 35 kg m-3, i.e. a porosity greater than 98%. A lower critical amount of aldehydes, 0.6 mmol g-1, was found necessary in order to generate a crosslinked 3-D CNF structure of sufficient strength not to collapse during the ambient drying. The chemical stability of the 3-D structure can be further enhanced by converting the hemiacetals to acetals by treatment with an alcohol under acidic conditions.

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  • 171.
    Esteves, Claudia
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Brännvall, Elisabet
    RISE Research Institutes of Sweden.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Sevastyanova, Olena
    KTH Royal Institute of Technology, Sweden.
    The effects of high alkali impregnation and oxygen delignification of softwood kraft pulps on the yield and mechanical properties2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 2, p. 223-231Article in journal (Refereed)
    Abstract [en]

    This study investigated whether the yield improvement after high alkali impregnation (HAI) is maintained after oxygen delignification and whether the potential of oxygen delignification to increase the mechanical properties is affected by high alkali impregnation. The yield improvement achieved by high alkali impregnation (1 %) was preserved after oxygen delignification, particularly of glucomannan. The total fiber charge and swelling increased after oxygen delignification regardless of the type of impregnation in the cooking step. The tensile index improvement obtained by oxygen delignification was retained if this was preceded by high alkali impregnation. The stiffness index was higher and elongation slightly lower after HAI impregnation than after a standard (REF) impregnation. Fibers obtained through high alkali impregnation seem to be slightly less deformed and slightly wider than fibers obtained after a standard impregnation. 

  • 172.
    Esteves, Claudia
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Sevastyanova, Olena
    KTH Royal Institute of Technology, Sweden.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Brännvall, Elisabet
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Differences and similarities between kraft and oxygen delignification of softwood fibers: effects on chemical and physical properties2021In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 28, no 5, p. 3149-3167Article in journal (Refereed)
    Abstract [en]

    The fiber properties after oxygen delignification and kraft pulping were studied by looking into the chemical characteristics and morphology. The effect of the two processes on the fibers was evaluated and compared over a wider kappa number range (from 62 down to15). Wide-angle X-ray scattering, nuclear magnetic resonance and fiber saturation point were used to characterize the fiber network structure. Fiber morphology and fiber dislocations were evaluated by an optical image analysis. The total and surface fiber charges were studied by conductometric and polyelectrolyte titrations. The fiber wall supramolecular structure, such as crystallinity, size of fibril aggregates, pore size and pore volume, were similar for the two processes. The selectivity, in terms of carbohydrate yield, was equal for kraft cooking and oxygen delignification, but the selectivity in terms of viscosity loss per amount of delignification is poorer for oxygen delignification. Clearly more fiber deformations (2–6% units in curl index) in the fibers after oxygen delignification were seen. Introduction of curl depended on the physical state of the fibers, i.e. liberated or in wood matrix. In the pulping stage, the fiber continue to be supported by neighboring fibers, as the delignified chips maintain their form. However, in the subsequent oxygen stage the fibers enter in the form of pulp (liberated fibers), which makes them more susceptible to changes in fiber form. Graphic abstract: [Figure not available: see fulltext.] © 2021, The Author(s).

  • 173.
    Esteves, Claudia
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Sevastyanova, Olena
    KTH Royal Institute of Technology, Sweden.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Brännvall, Elisabet
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Differences and similarities between kraft and oxygen delignification of softwood fibers: effects on mechanical properties2021In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 28, p. 3775-3788Article in journal (Refereed)
    Abstract [en]

    Charged groups in pulp have been shown to enhance the tensile strength of the paper produced from the pulp. Oxygen delignification introduces charged groups and it is of interest to determine how the delignification should be distributed between the cooking and the oxygen stage with respect to mechanical properties. A number of unbleached kraft cooked and oxygen delignified pulps within a wide kappa number range were produced and refined, and the effects of the refining on the morphology and mechanical properties were studied. The WRV correlated with the fiber charge and at a given fiber charge, kraft cooked and oxygen delignified pulps had the same WRV development in refining, although they had significantly different kappa numbers. The tensile strength development during refining depends on the fiber rigidity which is affected by the lignin content, the fiber charge and the chemical and mechanical processes used. Refining increased the curl of the kraft cooked pulps and decreased the curl of oxygen delignified pulps, irrespective of kappa number. A greater increase in tensile strength was seen for the pulps with a higher fiber charge and WRV, probably because of the greater degree of fibrillation achieved in the beating process. Despite the greater fiber deformation in the oxygen delignified pulps, the strength can be increased by a larger amount of charged groups and a greater swelling of the fibers. Graphic abstract: [Figure not available: see fulltext.] © 2021, The Author(s).

  • 174.
    Esteves, Claudia
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Sevastyanova, Olena
    KTH Royal Institute of Technology, Sweden.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Brännvall, Elisabet
    RISE Research Institutes of Sweden.
    The impact of bleaching on the yield of softwood kraft pulps obtained by high alkali impregnation: Bleaching and high alkali impregnation impact2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 4, p. 593-608Article in journal (Refereed)
    Abstract [en]

    High alkali impregnation (HAI) increases the total yield of softwood pulps following kraft cooking. This yield improvement is also maintained after oxygen delignification. This study evaluates how bleaching with either chlorine dioxide or hydrogen peroxide affects the final yield of samples obtained with standard and HAI. The chemical composition, viscosity, brightness, mechanical and morphological properties were studied. Compared to cooking after standard impregnation the yield improvement achieved by HAI was preserved in both types of bleaching sequences (2 % units for chlorine dioxide and 4 % units for hydrogen peroxide). The introduction of charged groups into the cellulose fibers was higher with hydrogen peroxide bleaching than with chlorine dioxide however, no significant impact was seen on the swelling or mechanical properties. The brightness was higher for the pulps bleached with chlorine dioxide compared with hydrogen peroxide. Hydrogen peroxide bleaching resulted in similar brightness development for both standard and HAI. Fibers bleached with chlorine dioxide had the highest curl index (16-17 %) compared to the fibers bleached with hydrogen peroxide (15 %). © 2022 the author(s)

  • 175.
    Faia, Pedro M.
    et al.
    University of Coimbra, Portugal; CEMUC Centre of Mechanical Engineering, Portugal.
    Krochak, Paul
    RISE, Innventia.
    Costa, Harold
    University of Coimbra, Portugal; CEMUC Centre of Mechanical Engineering, Portugal.
    Lundell, Fredrik
    KTH Royal Institute of Technology, Sweden.
    Silva, Rui
    University of Coimbra, Portugal; CIEPQPF Research Centre on Chemical Process and Forest Products, Portugal.
    Garcia, Fernando A. P.
    University of Coimbra, Portugal; CIEPQPF Research Centre on Chemical Process and Forest Products, Portugal.
    Rasteiro, Maria Graca
    University of Coimbra, Portugal; CIEPQPF Research Centre on Chemical Process and Forest Products, Portugal.
    A comparative study of magnetic resonance imaging, electrical impedance tomography and ultrasonic doppler velocimetry for semi-dilute fibre flow suspension characterisation2016In: International Journal of Computational Methods & Experimental Measurements, ISSN 2046-0546, E-ISSN 2046-0554, Vol. 4, no 2, p. 165-175Article in journal (Refereed)
    Abstract [en]

    Experimental comparisons between imaging techniques serve to provide confidence in the validity of each technique for the study of multiphase flow systems. Such cross-validation can establish the limitations of each technique quantitatively. In the present paper, the authors report efforts made on the characterization of semi-dilute, mono-dispersed suspensions of rayon fibres in turbulent water flow using Magnetic Resonance Imaging (MRI), Ultrasound Velocity Profiling (UVP) and Electrical Impedance Tomography (EIT). Increasing flow velocities and fibre concentration were studied using these three experimental techniques. For lower fibre concentrations more uniform distributions were observed and as flow velocity increased fibre agglomerations were found in the centre region of the pipe.

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  • 176.
    Fellers, Christer
    RISE, Innventia.
    Laminate Theory for Papermakers2009In: Paper Products Physics and Technology, Walter de Gruyter, 2009, p. 287-314Chapter in book (Other academic)
  • 177.
    Fellers, Christer
    RISE, Innventia.
    Paper physics2009In: Paper Products Physics and Technology, Walter de Gruyter, 2009, p. 25-67Chapter in book (Other academic)
  • 178.
    Fellers, Christer
    RISE, Innventia.
    The structure of paper and its modelling2009In: Paper Products Physics and Technology, Walter de Gruyter, 2009, p. 1-24Chapter in book (Other academic)
  • 179.
    Fellers, Christer N.
    et al.
    RISE, Innventia.
    Östlund, Sören
    KTH Royal Institute of Technology, Sweden.
    Mäkelä, Petri
    RISE, Innventia. Tetra Pak Packaging Solutions AB, Sweden.
    Evaluation of the Scott bond test method2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 231-236Article in journal (Refereed)
    Abstract [en]

    The Scott bond test is the most commonly used test method for quantifying the delamination resistance of paper and board. The objective of this investigation was to validate the hypothesis that the Scott bond value would be dominated by the total energy under the force elongation curve in a z-directional tensile test. The investigation comprised three types of hand sheets with comparatively low strength values. Three test methods were used to obtain the energy for delamination: 1) Z-test, a z-directional tensile test, 2) Scott bond test, and 3) Simulated Scott bond test, a Scott bond type of test performed in a hydraulic tensile tester. The test data were expressed as a correlation between the failure energy obtained from the Z-test and the other two tests. The results showed that the Scott bond test gave slightly higher values than the Z-test for the weakest paper, but that the value tended to be much higher for the stronger papers. On the other hand the Simulated Scott bond test tended to give lower values than the Z-test. High speed photography was used to reveal several energy consuming mechanisms in the Scott bond test that can explain why this test gave higher values than the Ztest. The lower values from the Simulated Scott bond values are more difficult to explain. At this stage we can suggest that the failure mechanism is different if the paper is delaminated by pure tension or by a gradual delamination as in the Scott bond test.

  • 180. Forsman, M.
    et al.
    Bernmark, E.
    Nilsson, B.
    Pousette, S.
    RISE, Innventia.
    Mathiassen, S.E.
    Participative development of packages in the food industry: Evaluation of ergonomics and productivity by objective measurements2012In: Work: A journal of Prevention, Assessment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, no SUPPL.1, p. 1751-1755Article in journal (Refereed)
  • 181. Francey, S.
    et al.
    Tran, H.
    Berglin, N.
    RISE, Innventia.
    Global survey on lime kiln operation energy consumption and alternative fuel usage2011In: TAPPI Journal, ISSN 0734-1415, no 8, p. 19-26Article in journal (Refereed)
  • 182. Francey, S.
    et al.
    Tran, H.
    Berglin, Niklas
    RISE, Innventia.
    Global survey on lime kiln operation, energy consumption and alternative fuel usage2010In: 2010 TAPPI PEERS Conference and 9th Research Forum on Recycling, 2010, Vol. 2, p. 1004-1069Conference paper (Refereed)
    Abstract [en]

    A survey on lime kiln operation and fuel usage was conducted through questionnaires distributed to pulp mills in nine countries in late 2008. Responses were received from 67 lime kilns at 59 pulp mills. This paper discusses the key findings from the survey with respect to kiln design parameters, operating data, control strategies, fuel types, energy consumption and operating issues; and where possible, compares them to the findings obtained from a similar survey conducted in 1991. Many improvements have been made over the past two decades to kiln design and operations, including the increased number of kilns that are equipped with product coolers and lime mud dryers, and the higher mud solids content. However, ring formation and dusting/high dust load remain the major operational issues amongst the respondents. Although few kilns have used alternative fuels to date, there is considerable industry interest in their use in the future. About two-thirds of the kilns have plans for implementing alternative fuels within the next five years.

  • 183.
    Galland, Sylvain
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Prakobna, Kasinee
    KTH Royal Institute of Technology, Swedenk.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Holocellulose Nanofibers of High Molar Mass and Small Diameter for High-Strength Nanopaper2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 8, p. 2427-2435Article in journal (Refereed)
    Abstract [en]

    Wood cellulose nanofibers (CNFs) based on bleached pulp are different from the cellulose microfibrils in the plant cell wall in terms of larger diameter, lower cellulose molar mass, and modified cellulose topochemistry. Also, CNF isolation often requires high-energy mechanical disintegration. Here, a new type of CNFs is reported based on a mild peracetic acid delignification process for spruce and aspen fibers, followed by low-energy mechanical disintegration. Resulting CNFs are characterized with respect to geometry (AFM, TEM), molar mass (SEC), and polysaccharide composition. Cellulose nanopaper films are prepared by filtration and characterized by UV-vis spectrometry for optical transparency and uniaxial tensile tests. These CNFs are unique in terms of high molar mass and cellulose-hemicellulose core-shell structure. Furthermore, the corresponding nanopaper structures exhibit exceptionally high optical transparency and the highest mechanical properties reported for comparable CNF nanopaper structures. (Graph Presented).

  • 184.
    Gamelas, José A. F.
    et al.
    University of Coimbra, Portugal.
    Pedrosa, Jorge
    University of Coimbra, Portugal.
    Lourenco, Ana F.
    University of Coimbra, Portugal.
    Mutjo, Peré
    University of Girona, Spain.
    Gonzalez, Israel
    University of Girona, Spain.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Singh, Gurvinder
    NTNU Norwegian University of Science and Technology, Norway.
    Ferreira, Paulo J. T.
    University of Coimbra, Portugal.
    On the morphology of cellulose nanofibrils obtained by TEMPO-mediated oxidation and mechanical treatment2015In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 72, p. 28-33Article in journal (Refereed)
    Abstract [en]

    The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres were assessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities during homogenization. It was shown that the nanofibrils production yield increases with the mechanical energy. The effect of mechanical treatment on the yield was confirmed by laser profilometry of air-dried nanocellulose films. However, no significant differences were detected regarding the nanofibrils width as measured by atomic force microscopy (AFM) of air-dried films. On the other hand, differences in size were found either by laser diffraction spectroscopy or by dynamic light scattering (DLS) of the cellulose nanofibrils suspensions as a consequence of the differences in the length distribution of both samples. The nanofibrils length of the more nanofibrillated sample was calculated based on the width measured by AFM and the hydrodynamic diameter obtained by DLS. A length value of ca. 600. nm was estimated. The DLS hydrodynamic diameter, as an equivalent spherical diameter, was used to estimate the nanofibrils length assuming a cylinder with the same volume and with the diameter (width) assessed by AFM. A simple method is thus proposed to evaluate the cellulose nanofibrils length combining microscopy and light scattering methods.

  • 185.
    Gard Timmerfors, Jessica
    et al.
    Umeå University, Sweden.
    Blomberg Saitton, David
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Processum.
    Sjölund, Torbjörn
    MoRE Research, Sweden.
    Jönsson, Leif J.
    Umeå University, Sweden.
    Impregnation of wood chips for acidic processes and the influence of wood chip length2018In: The 8th Nordic Wood Biorefinery Conference:  NWBC 2018: proceedings / [ed] Hytönen Eemeli, Vepsäläinen Jessica, Espoo: VTT Technical Research Centre of Finland , 2018, p. 195-195Conference paper (Other academic)
  • 186. Gebremeskel, G G
    et al.
    Aldaeus, Fredrik
    RISE, Innventia.
    Jacobs, Anna
    RISE, Innventia.
    Determination of lignin content in kraft black liquors using capillary zone electrophoresis2014Conference paper (Refereed)
  • 187.
    Gellerstedt, Göran
    RISE, STFI-Packforsk.
    Biorefinery lignins: A feedstock for chemicals and materials2008In: 2008 Nordic Wood Biorefinery Conference - Proceedings: NWBC 2008, 2008, p. 111-113Conference paper (Refereed)
    Abstract [en]

    The rapid expansion of bioethanol production will, in addition to fermentation of sugar and starch sources, also involve a conversion of lignocellulosic materials. In addition to carbohydrates, this will result in large amounts of lignin which can be used as process fuel but also serve as a feedstock for chemicals. Modern kraft mills constitute a second source of lignin since the energy balance is such that a partial outtake of lignin can be permitted. Irrespective of source, technical lignins must be upgraded, e.g. by purification in order to acquire properties which make them suitable as feedstock in value-added products.

  • 188.
    Gellerstedt, Göran L.F.
    et al.
    RISE, Innventia.
    Tomani, Per E.
    RISE, Innventia.
    Axegård, Peter
    RISE, Innventia.
    Backlund, Birgit
    RISE, Innventia.
    Lignin recovery and lignin-based products2013In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, p. 180-210Article in journal (Refereed)
  • 189.
    Geng, Lihong
    et al.
    South China University of Technology, China; Stony Brook University, USA.
    Peng, Xiangfang
    South China University of Technology, China.
    Zhan, Chengbo
    Stony Brook University, USA.
    Naderi, Ali
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Sharma, Priyanka R.
    Stony Brook University, USA.
    Mao, Yimin
    University of Maryland, USA; National Institute of Standards and Technology, USA.
    Hsiao, Benjamin S.
    Stony Brook University, USA.
    Structure characterization of cellulose nanofiber hydrogel as functions of concentration and ionic strength2017In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 12, p. 5417-5429Article in journal (Refereed)
    Abstract [en]

    Carboxylated cellulose nanofibers (CNFs), having an average width of 7 nm and thickness of 1.5 nm, were produced by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation method. The fiber cross-sectional dimensions were determined using small-angle X-ray scattering (SAXS), transmission electron microscopy and atomic force microscopy techniques, where the rheological properties under different concentration and ionic strength were also investigated. The formation of hydrogel was evidenced by increasing the CNF concentration or ionic strength of the solvent (water), while the gel structure in ion-induced CNF hydrogels was found to be relatively inhomogeneous. The gelation behavior was closely related to the segmental aggregation of charged CNF, which could be quantitatively characterized by the correlation length (Ο) from the low-angle scattering profile and the scattering invariant (Q) in SAXS.

  • 190.
    Ghose, Agneta
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Environmental Aspects of Norwegian production of pulp fibres and printing paper2013In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 57, p. 293-301Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to assess the environmental impacts of the Norwegian pulp and paper industry, considering the production of pulp fibres and printing paper. The pulp fibres included in this study are thermo-mechanical pulp and kraft pulp fibres, which differ with respect to the energy consumption and chemicals used during production. The assessed paper grades were super-calendered paper and newsprint. The study was a cradle to gate approach, and corresponds to an attributional life cycle assessment (LCA). The LCA was based on data collected from main pulp and paper producers in Norway. Importantly, aspects related to the increasing use of mineral fillers in the production of newsprints were assessed. The results showed that a reduction of more than 18% climate change impact (kg CO2 eq.) was achieved by increasing the fraction of fillers, in the newsprint furnish. Furthermore, the total climate change impact reduction depended on the applied energy mix. Assuming that the production of printing paper was based only on Norwegian energy mix, yielded a reduction of the climate change impact by more than 44% in 2011, compared to the production based on Scandinavian and European energy mix. Additionally, the input and output transport contributed to more than 20% impact in several cases. We thus concluded that the estimated environmental impacts were affected by; i) the furnish composition of a given paper quality, ii) the input and output transport and iii) the use of different primary grid energy sources.

  • 191.
    Gimaker, M.
    et al.
    RISE, Innventia.
    Östlund, M.
    Östlund, S.
    Wågberg, L.
    Influence of beating and chemical additives on residual stresses in paper2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, no 4, p. 445451-Article in journal (Refereed)
  • 192.
    Gimåker, Magnus
    et al.
    RISE, Innventia.
    Nygårds, Mikael
    RISE, Innventia.
    Wågberg, Lars
    Östlund, Sören
    Shear strength development between couched paper sheets during drying2011In: / [ed] Hirn, U., 2011, , p. 3Conference paper (Refereed)
  • 193. Girlanda, O.
    et al.
    Fellers, Christer
    RISE, STFI-Packforsk.
    Delamination position in multiply paperboard achieved by different testing methods2008In: Appita journal, ISSN 1038-6807, Vol. 61, no 2, p. 107-112Article in journal (Refereed)
    Abstract [en]

    The determination properties of nine commercial multiply board grades, both coated and uncoated, were measured using four testing methods, the Z-Directional Tensile Strength test (ZDTS), the Scott Bond Test (SBT), the Wheel Delamination Test (WDT), and the IGT method. The positions of delamination failure in the thickness direction were then recorded and compared. For the IGT tests, failure profiles and the final failure positions were evaluated. The results showed that the failures in the ZDTS, WDT and SBT tests mainly occur in the middle ply, whereas failure in the IGT tests occurs in the top plies as well as in the middle ply. Some boards presented also more than one failure position for the same type of test. The correlations between the different delamination resistances were also investigated. The WDT and SBT method showed a good correlation, whereas no correlation could be found between the other methods.

  • 194. Girlanda, O.
    et al.
    Fellers, Christer
    RISE, STFI-Packforsk.
    Modelling of delamination in paperboard during sheet offset printing2008In: Appita journal, ISSN 1038-6807, Vol. 61, no 2, p. 113-119Article in journal (Refereed)
    Abstract [en]

    Delamination of multiply paperboard during offset printing is caused by the ink tack induced forces applied on the surface of the board. The purpose of this investigation was to analyze the influence of mechanical properties of the plies and interface resistance on the delamination behaviour of the paperboard. Paperboard was modelled as a four-ply sandwich structure. A user-defined interface model described the mechanical behaviour of the interfaces between the plies. The results in terms of critical ink tack length and stress conditions in the interfaces at delamination initiation were defined for different ply structures. The delamination process in multiply paperboard was highly dependent on the stress concentration caused by the ink tack. The delamination always occurred in the interface between top and middle ply. The main stress component causing delamination was tensile stress in the thickness direction, whereas the interlaminar shear was less relevant. Bending stiffness and in-plane tensile stiffness influenced the critical ink tack length, but did not affect the stress situation at the delamination point.

  • 195.
    Gonzalez, Israel
    et al.
    University of Girona, Spain.
    Alcala, Manel
    University of Girona, Spain.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Vilaseca, Fabiola
    University of Girona, Spain.
    Boufi, Sami
    Université de Sfax, Tunisia.
    Mutjé, Peré
    University of Girona, Spain.
    From paper to nanopaper: evolution of mechanical and physical properties2014In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 4, p. 2599-2609Article in journal (Refereed)
    Abstract [en]

    In the present work the evolution of physical and mechanical properties of papers and nanopapers is studied. Handsheets made of eucalyptus fibres reinforced with 0, 25, 50, 75 and 100 wt% of nanofibrillated cellulose (NFC) content were fabricated using a Rapid Köthen-like equipment. The obtained papers and nanopapers were physical- and mechanically-characterized. The results showed a significant increase in density and a reduction of porosity in the samples during their transition from paper to nanopaper; besides, nanopapers were more transparent and smoother than normal papers. These physical changes where more evident with increasing amounts of NFC. Regarding mechanical properties, nanopapers with a 100 wt% content of NFC improved their strength and rigidity in 228 and 317 %, respectively, in comparison with normal papers. The evolution of strength and rigidity from paper to nanopaper was linear in relation to the amount of NFC, which means that the ultimate tensile strength was mainly dependant on nanofibril failure.

  • 196. Gorski, D.
    et al.
    Kure, K-A.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    On the relationship between improved energy efficiency in high-consistency refining, fibre and fines properties and critical paper properties2011Conference paper (Refereed)
  • 197. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Axelsson, P.
    Engstrand, P.
    Peroxide-based ATMP refining of Spruce: Energy efficiency, fibre properties and pulp quality2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 47-63Article in journal (Refereed)
  • 198. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Role of equipment configuration and process chemicals in peroxide-based ATMP refining of spruce2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 233-247Article in journal (Refereed)
  • 199.
    Gorski, Dmitri
    et al.
    Norske Skog Saugbrugs, Norway.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Olson, James
    University of British Columbia, Canada.
    Luukkonen, Antti
    Andritz Inc., USA.
    Fibre and fines quality development in pilot scale high and low consistency refining of ATMP2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, p. 872-881Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to characterise and compare the development of fibre and fines properties in high consistency (HC) and low consistency (LC) refining of mechanical pulp. Primary refined pulp was produced using the Advanced Thermo-Mechanical Pulp (ATMP) refining process. Pulps were characterized to evaluate external and internal fibrillation, fibre shape and dimensions, surface area of fines and the proportion of split fibres. Based on the results, a different mode of fibre development was proposed for LC and HC refining. The LC refining resulted in a greater reduction in the shives content and R30 Bauer-McNett fibre fraction. The reduced R30 fraction considerably increased the middle fibre fractions; however it showed no further development in terms of surface fibrillation. While HC refining resulted in a significant reduction in fibre wall thickness associated with fibre collapse and increase in external fibrillation, LC refining mainly generated structural changes, seen in fibre straightening and increased flexibility. The HC and LC refined pulps had different property profiles compared at equal handsheet tensile index. The LC refined pulps contained less long fibres and fines but significantly more middle fraction particles. Extensive internal fibrillation of the straighter LC refined fibres appeared to have compensated for lower fines content and external fibrillation, producing well bonded sheets with good tensile strength.

  • 200.
    Gorur, Yunus
    et al.
    KTH Royal Institute of Technology, Sweden.
    Reid, Michael
    KTH Royal Institute of Technology, Sweden.
    Montanari, Celine
    KTH Royal Institute of Technology, Sweden; Wallenberg Wood Science Center, Sweden.
    Larsson, Per Tomas
    RISE Research Institutes of Sweden. KTH Royal Institute of Technology, Sweden.
    Larsson, Per A.
    KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Advanced Characterization of Self-Fibrillating Cellulose Fibers and Their Use in Tunable Filters2021In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, no 27, p. 32467-32478Article in journal (Refereed)
    Abstract [en]

    Thorough characterization and fundamental understanding of cellulose fibers can help us develop new, sustainable material streams and advanced functional materials. As an emerging nanomaterial, cellulose nanofibrils (CNFs) have high specific surface area and good mechanical properties; however, handling and processing challenges have limited their widespread use. This work reports an in-depth characterization of self-fibrillating cellulose fibers (SFFs) and their use in smart, responsive filters capable of regulating flow and retaining nanoscale particles. By combining direct and indirect characterization methods with polyelectrolyte swelling theories, it was shown that introduction of charges and decreased supramolecular order in the fiber wall were responsible for the exceptional swelling and nanofibrillation of SFFs. Different microscopy techniques were used to visualize the swelling of SFFs before, during, and after nanofibrillation. Through filtration and pH adjustment, smart filters prepared via in situ nanofibrillation showed an ability to regulate the flow rate through the filter and a capacity of retaining 95% of 300 nm (diameter) silica nanoparticles. This exceptionally rapid and efficient approach for making smart filters directly addresses the challenges associated with dewatering of CNFs and bridges the gap between science and technology, making the widespread use of CNFs in high-performance materials a not-so-distant reality. 

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