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  • 301.
    Krochak, Paul J.
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy.
    Norman, Bo
    RISE - Research Institutes of Sweden, Bioeconomy.
    Hermansson, Lennart
    RISE - Research Institutes of Sweden, Bioeconomy.
    Holmqvist, Claes
    RISE - Research Institutes of Sweden, Bioeconomy.
    Headbox induced sheet variability2017In: PaperCon 2017 / [ed] TAPPI, 2017, Vol. 2, p. 673-680Conference paper (Other academic)
  • 302.
    Krochak, Paul
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Johansson, Klas
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    De San Pio, Ignacio
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    The effect of contact time between CPAM and colloidal silica on the flocculation behavior in the approach flow2021In: TAPPI Journal, ISSN 0734-1415, Vol. 20, no 1, p. 39-47Article in journal (Refereed)
    Abstract [en]

    Multicomponent wet-end systems have become increasingly common in papermaking, with the objective of improving the retention-formation-dewatering relationship. It is quite common to use at least a cationic polymer, often in combination with an anionic microparticle. In some cases, a fixative is also used. However, there is still debate on the optimal implementation of these systems. In particular, optimizing the contact time of the cationic polymer prior to addition of the anionic microparticle is still poorly understood. In this work, we investigate the effect of the contact time of a cationic polyacrylamide (CPAM) prior to addition of colloidal silica on the flocculation response in a flowing fiber suspension. The effect of using a fixative is also investigated. Focused beam reflectance measurements (FBRM) are combined with zeta-potential measurements for optimizing the addition levels of a two- and three-component system, as well as for elucidating the effect of contact time on CPAM performance. Trials are then performed on a pilot scale flow loop, where the time between addition of these two components is varied and the resulting flocculation response is characterized using high-speed filming and image anal. techniques. It is shown that the efficacy of CPAM can be improved through use of a fixative and that a longer CPAM contact time may be beneficial in terms of immediate flocculation; however, hydrodynamic shear tends to dominate the flocculation response regardless of contact time due to floc rupture.

  • 303.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Lucisano, Marco
    RISE, Innventia.
    Trends and drivers influencing papermaking and its products towards the future2014Conference paper (Refereed)
  • 304.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Lucisano, Marco F. C.
    RISE, Innventia.
    Trends and drivers influencing papermaking and its products towards the future2014Conference paper (Refereed)
    Abstract [en]

    "Papermaking towards the future" is a project investigating the current state and future of global paper manufacture. The project is a critical investigation into the most important questions for the industry today and into the future. What changes can be observed and are currently taking place? What are the challenges at present, and how will they manifest themselves going forward? In which areas is the outlook most promising for the paper industry and how are we going to get there? Through a combination of expert interviews, workshops, a Dephi survey with respondents in 21 different countries, a student survey, and months of our own research, we have identified what we believe are the most important drivers for global change and the most important growing trends in the paper and packaging industry going forward 20 years. Projecting the information collected throughout this project forward in time, we see a high likelihood that the paper and packaging industry will shift into one centred around bio-refining, where a broad range of forest based products will be produced to support a bio-based world. The future products creating the greatest return on investment will include bio-plastics, bio-chemicals, bio-energy, cellulose textiles, and paper-based packaging materials, where everything produced will be sustainably sourced and everything recycled. However, it is critical that the paper and packaging industry strategize today for this promising future of tomorrow, through investments in marketing, organization, and new product innovation. Moreover, it is important that the industry capitalize on their strong position within this potential bio-based world, by exploiting their fibre processing infrastructure, knowledge, and experience with producing sustainable and recycling products from the forest.

  • 305.
    Krochak, Paul
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Norman, Bo
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Practical Aspects of Retention Aids Addition on Web Structure Variability2018In: PaperCon 2018: Shaping the future throuch innovation, 2018, p. 6-15, article id FF3.2Conference paper (Refereed)
    Abstract [en]

    In this work, we report on a series of pilot scale production trials investigating the effect of addition location, dosage velocity ratio and dilution level of a single component retention system (CPAM) on filler retention, formation and in-plane web structure uniformity for a fine paper grade. Specifically, we considered addition levels (500 g/t and 1000 g/t), dosage velocity ratios (2 and 4.5), and pre-dilution (300x and 600x) and addition location (before and after the headbox pump). The in-plane distribution of fibre and filler material in the final product was then mapped in high resolution over 10m paper samples using moveable radiation emitters and detectors.It was shown that addition of CPAM before the headbox pump resulted in a reduction in filler retention and poor formation in the final product. The addition velocity ratio was shown to have only minor influence on retention, formation and web structure variability. However, low CPAM dilution levels resulted in a high degree of variability in the distribution of filler and fibre including streakiness. Moreover, at low dilution levels, the in-plane distribution of filler was highly correlated to that of the fibres. By optimizing the dilution level and addition location, conditions could be established to reduce CPAM addition levels without adversely affecting retention or product variability.

  • 306.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Norman, Bo
    RISE, Innventia.
    Techniques for improving mixing quality2014Conference paper (Refereed)
    Abstract [en]

    Assessing the quality of additives dosage and subsequent mixing can be difficult. In this work we present a set of techniques which can be used to assess the mixing quality of wet-end as well as assessing flow conditions which can promote and/or be detrimental to mixing quality. In the first part of this work we show how mixing quality can be studied at pilot-scale through studying the addition of cationic blue colour in a paper stock. Here, we show how the addition of cationic blue colour in place of retention polymers during production can reveal both transient and steady state flaws with the dosage and mixing strategy. We also show how more advanced measurement techniques, namely magnetic resonance imaging (MRI) and ultrasonic velocimetry profiling (UVP) can be used to assess non-uniformities in flow conditions which could deteriorate mixing. We also discuss practical and operational considerations when using these approaches.

  • 307.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Norman, Bo
    RISE, Innventia.
    Hermansson, Lennart
    RISE, Innventia.
    The flocculation response of a dual component retention system subject to different mixing conditions2016In: Paper Conference and Trade Show (PaperCon 2016), 2016, Vol. 2, p. 987-994Conference paper (Other academic)
    Abstract [en]

    In this work, we study the fibre flocculation response created by a dual component retention system subject to different addition and mixing conditions. The motivation for this work is to develop new approaches to optimize the performance of retention aids systems for improving the retention-formation relationship. We do so through a combination of pilot scale production trials in combination with semi-pilot scale flow visualization using a cationic Polyacrylamide (CPAM) polymer and silica micro-particle retention system. Specifically, we investigate the effects of local turbulence levels, hydrodynamic shear applied to the polymer phase, and the time between addition of the polymer, micro-particle and to the headbox/forming section. Results from our production trials showed that optimal retention system performance can be achieved when the polymer and micro-particle components are added only a fraction of a second from each other and from the headbox in the presence of high levels of turbulence and with exposure to minimum hydrodynamic shear. Under optimal conditions, the improvements in retention realized were over 50% with simultaneous improvements in formation in excess of 30% with respect to a reference case. We then attempt to understand the mechanisms for this optimal response by simulating the same addition and mixing conditions on an experimental flow loop. The suspension flocculation dynamics are studied by visualization in a transparent pipe section. It is shown that when the polymer is exposed to high shear, the suspension does not reflocculate, even after addition of the micro-particle, which correlated with low filler retention in the production trials. When turbulence levels remained low, the suspension flocculated very quickly upon addition of the components, reaching large floc sizes in a very short amount of time. This correlated to poor formation in the production trials. When the retention system components were added immediately downstream a turbulence source but not subjected to any additional shear, the fibre floc size remained small and showed a slow tendency toward reflocculation. These conditions correlated to optimal retention and formation in the production trials.

  • 308.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Schack, Susanne
    Fasci, Giuseppe
    Investigation of retention aid polymer degradation on a pilot scale flow loop2012Conference paper (Refereed)
  • 309.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Schack, Susanne
    RISE, Innventia.
    Fasci, Giuseppe Carmini
    RISE, Innventia.
    New insights into retention aids dosage and mixing2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 192-201Article in journal (Refereed)
    Abstract [en]

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

  • 310.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Söderberg, Daniel
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Faia, Pedro
    University of Coimbra, Portugal.
    Monitoring tools for efficient papermaking2014Conference paper (Refereed)
    Abstract [en]

    With efficient papermaking, the objective is to produce a product that meets a sufficiently high performance standard at the lowest possible cost for production. Production costs tend to centre around the use of energy, raw fibre materials, and fresh water. Poor control of unit papermaking processes can create unwanted variability in product qualities. This forces producers to use excessive amounts of resource, including fibre raw material and energy in order to meet minimum product requirements. Control of unit processes is therefore an essential ingredient to efficient papermaking. One of the key challenges with process control is the ability to monitor accurately specific processes with a high spatial and temporal resolution in order to capture unwanted variability. New measurement methods have, within recent years, revealed surprisingly high levels of variability in many unit process, in product properties, and in the underlying structure of paper sheets. In particular, variability on the centimetre (or millisecond) scale is now understood to be significant. This work presents an overview of three novel measurement tools and their application for monitoring different stages of the paper production process. Specifically, the tools discussed here include, Electrical Impedance Tomography (EFT), STFI Online Forming Analyser (SOFA), and Infrared Thermography (IR) techniques. Potential implementations of each tool within different unit processes on a papermachine are supported by practical examples. When used together, it is shown that it could be possible to monitor the entire production line with enough accuracy for online control.

  • 311.
    Krochak, Paul
    et al.
    RISE, Innventia.
    Thomson, Lars
    RISE, Innventia.
    A new method for characterizing turbulent mixing in semi-concentrated suspensions2011Conference paper (Refereed)
  • 312.
    Krochak, Paul
    et al.
    RISE, Innventia.
    ֖stlund, Catherine
    RISE, Innventia.
    The effect of press nip geometry and web temperature on dryness, density and paper properties2017In: Paper Conference and Trade Show: Renew, Rethink, Redefine the Future, PaperCon 2017, TAPPI Press, 2017, Vol. 1, p. 297-300Conference paper (Refereed)
  • 313.
    Krochak, Paul
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy.
    ֖stlund, Catherine
    RISE - Research Institutes of Sweden, Bioeconomy.
    The effect of press nip geometry on dryness, density and paper properties2017In: 16th Fundamental research symposium, 2017, p. 323-343Conference paper (Refereed)
  • 314.
    Krochak, Paul
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Östlund, Catherine
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Tysen, Aron
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    The effect of felt-web structure interaction on press dryness variability2019In: International Paper Physics Conference 2019 : preprint proceedings: PaperCon 2019, TAPPI Press, 2019, p. 175-180Conference paper (Other academic)
    Abstract [en]

    Laboratory trials were carried out in order to clarify the interaction between felt and web structure and its impact on dryness variability. Oriented laboratory sheets of 80gsm and consisting of 100% never dried unbleached softwood kraft were prepared using a dynamic sheet former. The sheets were pressed with two different orientations; aligned with the felt aligned in the machine direction or with web aligned in the cross direction. The wet web samples were immediately transferred after pressing to a hot plate and dried under restraint. A bench-scale method was developed using near infrared (NIR) imaging in order to characterise the interaction between felt and web structure during pressing and drying. It was found that the average press dryness had a low dependence on interactions between web and felt structure. Moisture variability in the interaction layer was found to be highly dependent on the web fibre orientation relative to the press felt. High levels of moisture variability on the web surface were observed with large differences in fibre alignment. It was observed that moisture variations in the web surface after pressing continued through the drying process and further increased the total drying time of the paper web.

  • 315.
    Krochak, Paul
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    ֖stlund, Ida
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Ankerfors, Caroline
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Gimåker, Magnus
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Waljanson, Alexander
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Hermansson, Lennart
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Possible benefits of adding retention aids as well as cationic starch for dry strength very close to the headbox2017In: Paper Conference and Trade Show: Renew, Rethink, Redefine the Future, PaperCon 2017, TAPPI Press, 2017, Vol. 2, p. 695-704Conference paper (Other academic)
    Abstract [en]

    Previous research made at RISE Bioeconomy (former Innventia) has shown significant improvements to both retention and formation when retention AIDS, cationic polyacrylamide (C-PAM) and microparticulate silica, were added very close to the headbox given that the mixing was adequate. The pilot trial that showed these results used a somewhat idealised system since the furnish used consisted solely of fibre, filler and retention aid. In addition to these components, it is very common to add some cationic starch to the thick stock to increase the paper strength. When cationic starch (0.5%) had been added to the thick stock there was no longer any obvious positive effect on the retention-formation relationship with the late dosage of the retention system. This spurred a further investigation and trials in which also the cationic starch was added just prior to the headbox, such that the contact times of all three components (C-PAM, microparticulate silica and cationic starch) were less than 3 seconds prior to forming. Also in these cases, the general positive effect on the formation-retention relationship was not seen, but the C-PAM dosage needed to obtain a certain retention level was much less as compared to when the normal dosage positions were used. This clearly demonstrates possibilities to drastically decrease the C-PAM consumption. Only marginal negative effect on the mechanical properties of the produced paper was seen when the starch was added just prior to the headbox as compared to in the thick stock. It is common wisdom that starch should have a long contact time to give optimal strength gain. The presented results show that this needs not to be the case, and the key is probably adequate mixing.

  • 316.
    Kronqvist, Malin
    et al.
    RISE, Innventia.
    Kulander, Ida
    RISE, Innventia.
    Promoting sustainable decisions at pulp mill biorefineries with LCA2014Conference paper (Refereed)
  • 317.
    Kumar, Vinay
    et al.
    Åbo Akademi University, Finland.
    Ottesen, Vegar
    NTNU, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Gregersen, Öyvind Weiby
    NTNU, Norway.
    Toivakka, Martti
    Åba Akademi University, Finland.
    Coatability of cellulose nanofibril suspensions: Role of rheology and water retention2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 7656-7679Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibril (CNF) suspensions are not easily coatable because of their excessively high viscosity and yield stress, even at low solids concentrations. In addition, CNF suspensions vary widely in their properties depending on the production process used, which can affect their processability. This work reports roll-to-roll coating of three different types of CNF suspensions with a slot-die, and the influence of rheology and water retention on coatability is addressed. The impact of CMC addition on the high and low shear rate rheology, water retention, coatability, and final coating quality of these suspensions is reported. All three CNF suspensions were coated successfully using the slot-die coating process. CMC addition further improved the coatability by positively influencing both the low and high shear rate viscosity and water retention of the CNF suspensions. All CNF coatings significantly improved the air, heptane vapor, grease and oil barrier, while reducing the water vapor transmission rate to some extent.

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  • 318.
    Köhnke, Tobias
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Coagulation and structure formation of cellulose from EmimAc- DMSO solutions2015Conference paper (Other academic)
  • 319. Köhnke, Tobias
    et al.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Investigations into the coagulation of cellulose from EmimAc: DMSO solutions in common protic solvents2015Conference paper (Other academic)
  • 320. Laaksometsä, C.
    et al.
    Axelsson, E.
    Berntsson, T.
    Lundström, Anders
    RISE, STFI-Packforsk.
    Energy savings combined with lignin extraction for production increase: Case study at a eucalyptus mill in Portugal2009In: Clean Technologies and Environmental Policy, ISSN 1618-954X, E-ISSN 1618-9558, Vol. 11, no 1, p. 77-82Article in journal (Refereed)
    Abstract [en]

    In previous research by the authors, energy savings combined with lignin extraction as a means to debottleneck the recovery boiler were evaluated on a model mill. The study showed that this concept was a profitable alternative to recovery boiler upgrade. In the present paper the concept was taken one step further, and the potential for energy savings and possibilities for lignin extraction were evaluated at a real mill: a market pulp mill in Portugal. The energy-saving methods proved to be applicable also to the real mill and the steam-saving potential was 4.2 GJ/ADt or 33%. Lignin extraction trials with bench scale equipment showed that lignin extraction was fully viable at the studied mill. A full-scale lignin separation plant according to the LignoBoost concept, combined with energy savings, was simulated in a computer environment and compared to installation of a new recovery boiler. A new recovery boiler had an investment cost four times higher than the LignoBoost concept combined with energy savings, but the electricity production would be higher. The profitability for a production increase of 16% was calculated for both cases. Steam savings combined with LignoBoost were found to have better profitability unless the electricity price is very high. © 2008 Springer-Verlag.

  • 321.
    Larsson, Mårten
    et al.
    KTH Royal Institute of Technology, Sweden.
    Jansson, Mikael
    RISE, Innventia.
    Grönkvist, Stefan
    KTH Royal Institute of Technology, Sweden.
    Alvfors, Per
    KTH Royal Institute of Technology, Sweden.
    Techno-economic assessment of anaerobic digestion in a typical Kraft pulp mill to produce biomethane for the road transport sector2015In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 104, p. 460-467Article in journal (Refereed)
    Abstract [en]

    Renewable waste-based fuels may decrease the resource use and environmental impact of the road transport sector; one of the options is biogas produced via anaerobic digestion of waste streams from pulp and paper mills. This paper describes process simulation and economic assessments for two options for integrating anaerobic digestion and production of liquid biogas in a typical Nordic Kraft pulp mill: (1) a high-rate anaerobic reactor in the wastewater treatment, and (2) an external anaerobic stirred tank reactor for the treatment of primary and secondary sludge as well as Kraft evaporator methanol condensate. The results revealed an annual production potential of 26-27 GWh biogas in an average Nordic Kraft pulp mill, which is equivalent to a daily production of 7600 L of diesel in terms of energy, and the production cost was estimated to €0.47-0.82 per litre diesel equivalent, comparable with the Swedish price of €0.68 per litre diesel. However, for the cases with liquid biogas (LBG), a discounted payback period of about 8 years may not be considered profitable by the industry. Other pre-requisites may, however, improve the profitability: a larger mill; production of compressed biogas instead of liquid biogas; or, for case 1, a comparison with the alternative cost for expanding the wastewater treatment capacity with more process equipment for activated sludge treatment. The results reveal that anaerobic digestion at pulp mills may both expand the production of renewable vehicle fuel but also enable increased efficiency and revenue at Kraft pulp mills.

  • 322. Larsson, P. A.
    et al.
    Hoc, Miroslav
    RISE, Innventia.
    Wågberg, L.
    A novel approach to study the hydroexpansion mechanisms of paper using spray technique2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 4, p. 371-380Article in journal (Refereed)
    Abstract [en]

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

  • 323.
    Larsson, Per Tomas
    RISE, Innventia.
    Solid state NMR as a tool for measuring pore sizes in water swollen cellulose fibre walls2013Conference paper (Refereed)
  • 324.
    Larsson, Per Tomas
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Alfthan, Johan
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Simeonova, Galya
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Holmqvist, Claes
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Changes in the macro and nano-structure of paper during moisture cycling2023In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    Hygroexpansion, CP/MAS 13C-NMR, WAXS and SAXS measurements were carried out on sheets made from four different commercial pulps of varying lignin content. Non-directional laboratory sheets were made at different press levels from the pulps following different degrees of beating. The sheets were dried both freely and with restraints. Measurements were made on sheets before and after moisture cycling to determine hygroexpansion coefficients, changes in cellulose average lateral fibril dimensions and average cellulose crystallite sizes, with the aim of understanding macroscale and nanoscale changes as the result of moisture cycling. Within the sheets consistent and statistically significant structural changes were observed on both macro and nanoscale. On the macroscale, moisture cycling consistently induced irreversible shrinkage in sheets dried with restraints, but less so in the case of sheets dried freely. The hygroexpansion coefficients were typically higher for freely dried sheets compared with sheets dried with constraints. On the nanoscale, moisture cycling consistently caused an increase in the average crystallite sizes (WAXS) and the average lateral fibril dimensions (CP/MAS 13C-NMR), though the latter occurred with poor statistical significance. These changes were interpreted as an increase in the degree of order in the cellulose fibril interior/cellulose crystallite. There were no profound differences in the nanoscale changes observed for sheets dried with restraints and for sheets dried freely. Changes in the fibre wall nanostructure were of similar magnitudes when comparing results from freely dried low grammage sheets (less abundant inter-fibre joints) with freely dried sheets of higher grammage (more abundant inter-fibre joints). No obvious correlations were found between the macroscale and nanoscale measurements. The proposed explanation for this was that the nanoscale structural changes occurred similarly throughout the entirety of the fibre wall, independent of the proximity to an inter-fibre joint, and that the nanoscale structural changes were mainly the result of water penetrating into the interior of cellulose fibril aggregates. By using the same fibril model for evaluation of CP/MAS 13C-NMR and WAXS data, good-to-reasonable agreement were found for estimates of the degree of cellulose crystallinity. 

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  • 325.
    Larsson, Per Tomas
    et al.
    RISE, Innventia.
    Salmen, Lennart
    RISE, Innventia.
    Influence of cellulose supramolecular structure on strength properties of chemical pulp2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 8, p. 861-866Article in journal (Refereed)
    Abstract [en]

    The industrially produced chemical pulps have lower strength properties than those obtained under laboratory conditions, and this difference is referred to as the strength delivery (SD) problem. In this study, the hypothesis was put forward that the SD could, at least in part, be accounted for by the supramolecular structure of the cellulose microfibrils of the fiber wall. To test the hypothesis, two bleached softwood kraft pulps (BSKP) were manufactured from the same starting material with different degrees of cellulose aggregation, but the pulps were otherwise as similar as possible in other controllable respects. The chemical and physical properties, including the pulp strength, were tested. A selective increase of the degree of cellulose microfibril aggregation resulted in a pulp with a decreased tear index (TI) at a specified tensile index, and this decrease was similar in magnitude to what is typically encountered in SD. Accordingly, the current experimental study succeeded in mimicking the SD problem. The lateral fibril aggregate dimensions (LFAD) seem to play a pivotal role and it can be safely concluded in general that the supramolecular structure of cellulose in the fibers may be an important factor contributing to the SD problem.

  • 326.
    Larsson, Per Tomas
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Svensson, Anna
    KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars Göran
    KTH Royal Institute of Technology, Sweden.
    A new, robust method for measuring average fibre wall pore sizes in cellulose I rich plant fibre walls2013In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 2, p. 623-631Article in journal (Refereed)
    Abstract [en]

    A new, robust method for measuring the average pore size of water-swollen, cellulose I rich fibres is presented. This method is based on the results of solid-state NMR, which measures the specific surface area (area/solids mass) of water-swollen samples, and of the fibre saturation point (FSP) method, which measures the pore volume (water mass/solids mass) of water-swollen samples. These results are suitable to combine since they are both recorded on water-swollen fibres in excess water, and neither requires the assumption of any particular pore geometry. The new method was used for three model samples and reasonable average pore size measurements were obtained for all of them. The structural characterization of water-swollen samples was compared with the dry structure of fibres as revealed using BET nitrogen gas adsorption after a liquid exchange procedure and careful drying. It was concluded that the structure of the water-swollen fibres sets an upper limit on what is obtainable in the dry state.

  • 327.
    Larsson, Per Tomas
    et al.
    RISE, Innventia.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Wohlert, Jakob
    KTH Royal Institute of Technology, Sweden.
    Bergenstråhle, Malin
    KTH Royal Institute of Technology, Sweden.
    Changes in the supra-molecular structure of cellulose I during TEMPO-oxidation: bringing together NMR, MD and XRD results2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 35-35, article id 9Conference paper (Other academic)
  • 328.
    Lecourt, Micheal
    et al.
    FCBA, France.
    Pöhler, Tiina
    VTT, Finland.
    Hornatowska, Joanna
    RISE - Research Institutes of Sweden, Bioeconomy.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Jetsu, Petri
    VTT, Finland.
    Density profiles of novel kraft pulp and TMP based foam formed thermal insulation materials observed by X-ray tomography and densitometry2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 5, p. 397-403Article in journal (Refereed)
    Abstract [en]

    X-ray tomography and densitometry (XRT and XRD) were applied to characterise wood fibre based insulation materials, which were produced by the foam forming technology. XRT is a high resolution approach with long measurement times of around 29 h, while XRD measurement needs only a few minutes. The determination of density distribution of boards in the thickness direction was the focus of this study. Both approaches visualised well the impact of raw materials and manufacturing processes on the structure of the panels. The density profiles were dependent on the pulp applied for panel production, and the processing conditions were also influential. Air flow resistance correlated with the maximum density measured inside the board. Both XRT and XRD revealed similar trends, which are useful for the characterisation of insulation materials.

  • 329.
    Li, Dongfang
    et al.
    KTH Royal Institute of Technology, Sweden.
    Iversen, Tommy
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Ek, Monica
    KTH Royal Institute of Technology, Sweden.
    Treatment of a cellulose fiber surface with a suberin monomer-derived polymer2015In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 6, no 3, p. 75-90Article in journal (Refereed)
    Abstract [en]

    The biorefinery concept requires the development of value-added products, such as materials from biomass, including bark. Suberin is the most abundant component in birch (Betula verrucosa) outer bark and acts as a barrier against the penetration of water and external attacks from microorganisms. The aliphatic domain of suberin is rich in hydroxy fatty acids, such as cis-9,10-epoxy-18- hydroxyoctadecanoic acid. In this study, it was isolated from the outer bark of birch and polymerized to prepare polyepoxy acid (PEA), which was used to impregnate filter papers. After complete drying, PEA-loaded filter papers were placed under UV to crosslink the epoxides through cationic polymerization with a diaryliodonium salt as the photo-initiator. The crosslinking was evaluated using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The materials obtained after UV curing showed substantially increased hydrophobicity, decreased moisture absorption, increased tensile strength, and increased ductility. Field-emission scanning electron microscopy (FE-SEM) showed that the crosslinked PEA covered the surface of the cellulose fibers and filled the interstitial spaces.

  • 330.
    Li, Jiebing
    RISE, Innventia.
    Carbonised adsorbents from softwood kraft lignin2014Conference paper (Refereed)
  • 331.
    Li, Jiebing
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. KTH Royal Institute of Technology, Sweden.
    Wang, Miao
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. KTH Royal Institute of Technology, Sweden.
    She, Diao
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. Chinese Academy of Sciences & Ministry of Water Resources, China.
    Zhao, Yadong
    KTH Royal Institute of Technology, Sweden.
    Functionalization of softwood kraft lignin for coating urea as highly efficient nitrogen fertilizer2017In: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017: NWBC 2017, Stockholm: RISE Bioekonomi , 2017, p. 244-245Conference paper (Refereed)
    Abstract [en]

    An industrial softwood kraft lignin (SKL) was blended with polylactic acid (PLA) and used for complex coating of urea as nitrogen fertiliser. The coating was perfumed using a simple and cheap dip-coating technique. The lignin was pre-functionalised via esterification or Mannich reaction. Esterification rendered a lignin derivative with higher hydrophobicity, while the Mannich reaction introduced organically bound nitrogen onto the lignin derivative structure. It was found that the coating resulted in good attachment of the coating layer on the surface of urea pellets. The coating layer was very compact and the wall layer was rather homogeneous and well distributed. The urea coating not only constructed a physical barrier to delay urea dissolution (controlled release), but also supplied chemically slow-release, organically bound nitrogen and biological stabilisation effects. It was found that the Mannich reaction product (ManSKL/PLA) slowed down the urea release more than the PLA coating reference, taking approximately 1m000s or 6.7 times as long

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  • 332.
    Li, Xin
    et al.
    Beijing Institute of Graphic Communication, China.
    Liu, Jianghao
    Beijing Institute of Graphic Communication, China.
    Wei, Xianfu
    Beijing Institute of Graphic Communication, China.
    Huang, Beiqing
    Beijing Institute of Graphic Communication, China.
    Zhang, Fuzhong
    Beijing Institute of Graphic Communication, China.
    Yang, Li
    RISE, Innventia.
    Research on the permeability of ink in offset paper2014In: Applied Mechanics and Materials, ISSN 1660-9336, E-ISSN 1662-7482, Vol. 469, p. 313-317Article in journal (Refereed)
    Abstract [en]

    First, the study chooses ten kinds of offset paper. By using a dynamic penetration analyzer (HVL-PDA) and water as test fluid, the dynamic absorption characteristics of the ten kinds of offset paper are measured. At the same time, proofs of offset printing patterns of these ten kinds of offset paper are made by using a printability tester. Then the depths of ink penetration in ten kinds of offset paper are measured by the Three-dimensional video microscopy system and the study analyzes the effect of paper dynamic absorption property on penetration depth of ink. The results of the analyses show that the penetration depth of ink is closely related to dynamic liquid absorption, thus the permeability of ink in offset paper can be predicted from the dynamic liquid absorption of offset paper.

  • 333.
    Lindberg, Siv M
    et al.
    RISE, Innventia.
    Hansen, Peeter
    RISE, Innventia.
    Drotz, Mattias
    RISE, Innventia.
    Kihlstedt, Annika
    RISE, Innventia. RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Rosén, Fredrik
    RISE, Innventia.
    Tactile and instrumental characterization of tissue products2015Conference paper (Other academic)
    Abstract [en]

    The feeling of softness and smoothness of paper tissue products is an important performance factor in the market place. In a series of panel tests, the relationship between instrumental measurements and perceived softness and smoothness was investigated. Samples of tissue base paper – napkin and toilet paper – were evaluated for surface roughness. The samples were placed on a hard, smooth glass substrate and the respondents used one finger to stroke along the sample surface. Instrumental measurement and characterization were performed using differentinstruments: Emtec TSA and Lena Softness Tester. The results divide the base paper material into product groups, but general mathematical relationships could be found between the test panel and the measurements when normalized in different ways. Measurements using the Lena produced the best correlation with the panel ratings because its principle resembled the method of the test panel most closely. However, a general relationship usingmaterial properties was shown to produce as good an estimator for the surface roughness as the results obtained with the Lena. This relationship consisted of the ratio between the plasticity and the elasticity of the tissue paper (in-plane properties), normalized for thickness. This suggests that those three material properties are fundamental to the perception of surface roughness as evaluated in this study. Using a trained haptic panel to evaluate test samples of similar grammage with variations in furnish and machine operation settings generated a good correlation to the TSA measurement (r=0.9). The panel was more susceptible to variation in furnish than variation in peak pressure, and this was particularly evident for samples evaluated on the Yankee side.

  • 334.
    Lindberg, Siv M
    et al.
    RISE, Innventia.
    Lindström, Annika
    RISE, Innventia.
    Cederström, Caroline
    RISE, Innventia.
    From, Anders
    Westerlind, Christine
    Shoppers' attention to packaging and in-store media2013Conference paper (Refereed)
  • 335.
    Lindgren, Karin
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Kulander, Ida
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Törngren, Per
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biobased Materials.
    Bialik, Marta
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Soap separation: A new option for removal of NPEs2018In: Pulping Engineering and Environmental Recycling Sustainability Conference, PEERS 2018: Technical Solutions for Today and Beyond, TAPPI Press , 2018, p. 272-277Conference paper (Other academic)
    Abstract [en]

    Non-process elements (NPEs) are elements present in the process streams without taking part in the desired reaction. With increasing process closure and new NPE-rich input streams such as gasified bark in the lime kiln and the destruction of biosludge in the recovery boiler, the traditional purge points may prove insufficient. A new method to remove NPEs is suggested: Removal of NPEs from tall oil brine. The idea is based on the fact that many elements are enriched in the soap and separated from the black liquor but are later led back to the black liquor with the brine. The results showed strong enrichment of Ba, Ca, Mg, Mn, P and Zn in soap; an enrichment factor of 8 or higher was observed. Laboratory experiments where tall oil brine has been alkalized and subjected to a separation stage have been conducted. The laboratory experiments showed that more than 90% of Al, Ba, Mg, Mn and P precipitates and could be removed with the solid phase if alkalized to pH 11. The separation efficiency varied for Ca and Si from 70-85 %. To conclude, removal of non-process elements from tall oil brine is a promising new kidney, especially for P and Si.

  • 336.
    Lindgren, Karin
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Kulander, Ida
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Törngren, Per
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Bialik, Marta
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biorefinery and Energy.
    Soap separation: a new option for removal of NPEs2018In: Technical solutions for today and beyond: TAPPI PEERS conference, 2018, p. 154-159Conference paper (Other academic)
  • 337.
    Lindgren, Karin
    et al.
    RISE, Innventia.
    Samuelsson, Åsa
    RISE, Innventia.
    Kulander, Ida
    RISE, Innventia.
    Full mill model for dissolving pulp based biorefinery2015Conference paper (Other academic)
    Abstract [en]

    Material and energy balances of a modern theoretical dissolving softwood kraft pulp mill, using pre-hydrolysis in water, have been established. The mill produces 1000 ADt/day and there is an energy excess in the mill that could be used to produce power. If lignin is removed with the LignoBoost process the recovery boiler is unloaded enabling an increased pulp production. With a lignin removal of 0.2 ton/ADt the pulp production could increase 8.5%. According to a sensitivity analysis the lignin price has the largest impact on the economic performance.

  • 338.
    Lindgren, Karin
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy.
    Samuelsson, Åsa
    RISE - Research Institutes of Sweden, Bioeconomy.
    Kulander, Ida
    RISE - Research Institutes of Sweden, Bioeconomy.
    Techno economic evaluation of lignin extraction in a dissolving pulp biorefinery2017In: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017: NWBC 2017, Stockholm: RISE Bioekonomi , 2017, p. 118-123Conference paper (Refereed)
    Abstract [en]

    A simulation model for dissolving pulp production using prehydrolysis kraft process has been developed at Innventia, which reflects a greenfield dissolving softwood kraft pulp mill producing 1,000tpd. The fibrelines comprised a separate prehydrolysis stage before the impregnation stage, with condensate from black liquor evaporation and steam being added to the prehydrolysis stage. The liquor was then removed from the chips and fed to the evaporation plant. The prehydrolysed chips were subjected to impregnation, cooking and oxygen delignification in double stages, with the oxygen delignified pulp being bleached in a four stage sequence D1(EOP)D2P. The simulation program WinGEMS 5.0 was used to establish material and energy balances. A lignin production of 0.2t/t increased pulp production by 8.5%. The heat value of the black liquor decreased but would still be high enough for stable and favourable combustion properties in the recovery boiler. It was found that the lignin price had the largest impact on the economic performance. Lignin removal increased the pulp production and was economically viable, especially if the possibility to produce electricity was low.

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  • 339.
    Lindh, Erik L.
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Bergenstråhle-Wohlert, Malin
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Terenzi, Camilla
    KTH Royal Institute of Technology, Sweden.
    Salmen, Lennart
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Furo, István
    KTH Royal Institute of Technology, Sweden.
    Non-exchanging hydroxyl groups on the surface of cellulose fibrils: The role of interaction with water2016In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 434, p. 136-142Article in journal (Refereed)
    Abstract [en]

    The interaction of water with cellulose stages many unresolved questions. Here 2H MAS NMR and IR spectra recorded under carefully selected conditions in 1H-2H exchanged, and re-exchanged, cellulose samples are presented. It is shown here, by a quantitative and robust approach, that only two of the three available hydroxyl groups on the surface of cellulose fibrils are exchanging their hydrogen with the surrounding water molecules. This finding is additionally verified and explained by MD simulations which demonstrate that the 1HO(2) and 1HO(6) hydroxyl groups of the constituting glucose units act as hydrogen-bond donors to water, while the 1HO(3) groups behave exclusively as hydrogen-bond acceptors from water and donate hydrogen to their intra-chain neighbors O(5). We conclude that such a behavior makes the latter hydroxyl group unreactive to hydrogen exchange with water.

  • 340.
    Lindh, Erik L.
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia. KTH Royal Institute of Technology, Sweden .
    Terenzi, Camilla
    KTH Royal Institute of Technology, Sweden .
    Salmen, Lennart
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia. KTH Royal Institute of Technology, Sweden .
    Furo, Istvan
    KTH Royal Institute of Technology, Sweden .
    Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by 2H MAS NMR2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, p. 4360-4369Article in journal (Refereed)
    Abstract [en]

    The organization of water molecules adsorbed onto cellulose and the supramolecular hydrated structure of microfibril aggregates represents, still today, one of the open and complex questions in the physical chemistry of natural polymers. Here, we investigate by 2H MAS NMR the mobility of water molecules in carefully 2H-exchanged, and thereafter re-dried, microcrystalline cellulose. By subtracting the spectral contribution of deuteroxyls from the spectrum of hydrated cellulose, we demonstrate the existence of two distinct 2H2O spectral populations associated with mobile and immobile water environments, between which the water molecules do not exchange at the NMR observation time scale. We conclude that those two water phases are located at differently-accessible adsorption sites, here assigned to the cellulose surfaces between and within the microfibril aggregates, respectively. The superior performance of 2H MAS NMR encourages further applications of the same method to other complex systems that expose heterogeneous hygroscopic surfaces, like wood cell walls.

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  • 341.
    Lindh, Erik
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Surface accessibility of cellulose fibrils studied by hydrogena€“deuterium exchange with water2017In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 1, p. 21-33Article in journal (Refereed)
    Abstract [en]

    A problem with cellulose-based materials is that they are highly influenced by moisture, leading to reduced strength properties with increasing moisture content. By achieving a more detailed understanding of the water–cellulose interactions, the usage of cellulose-based materials could be better optimized. Two different exchange processes of cellulose hydroxyl/deuteroxyl groups have been monitored by transmission FT-IR spectroscopy. By using line-shape-assisted deconvolution of the changing intensities, we have been able to follow the exchange kinetics in a very detailed and controlled manner. The findings reveal a hydrogen exchange that mainly is located at two different kinds of fibril surfaces, where the differences arise from the water accessibility of that specific surface. The slowly accessible regions are proposed to be located between the fibrils inside of the aggregates, and the readily accessible regions are suggested to be at the surfaces of the fibril aggregates. It was also possible to identify the ratio of slowly and readily accessible surfaces, which indicated that the average aggregate of cotton cellulose is built up by approximately three fibrils with an assumed average size of 12 × 12 cellulose chains. Additionally, the experimental setup enabled visualizing and discussing the implications of some of the deviating spectral features that are pronounced when recording FT-IR spectra of deuterium-exchanging cellulose: the insufficient red shift of the stretching vibrations and the vastly decreasing line widths.

  • 342.
    Lindström, Tom
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Aspects on nanofibrillated cellulose (NFC) processing, rheology and NFC-film properties2017In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 29, p. 68-75Article in journal (Refereed)
    Abstract [en]

    This communication summarizes the salient features and mechanisms in high-pressure homogenization of wood fibres in order to make nanofibrillar cellulose (NFC). The energy-efficiency of delamination of fibres and the clogging tendency of fibres in high-pressure homogenizers/microfluidizers during delamination are critical and ways to alleviate these problems are reviewed. It is shown that the mechanical properties of NFC-films can be estimated from the Page equation. Usually, the evolution of the tensile strength properties of NFC-films increases with the extent of film delamination to reach a saturation value, which can be deduced from first principles using the Page equation. Finally, the evolution of the rheological features of NFC-gels and the barrier properties are reviewed and the estimation the nanofraction content in NFC-gels is being discussed.

  • 343.
    Lindström, Tom
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Aulin, Christian
    RISE, Innventia.
    Gimåker, Magnus
    RISE, Innventia.
    Persson, Torgny
    KTH Royal Institute of Technology, Sweden.
    The emergence of practical nanocellulose applications for a more sustainable paper/board industry2014In: IPPTA: Quarterly Journal of Indian Pulp and Paper Technical Association, ISSN 0379-5462, Vol. 26, no 1, p. 53-61Article in journal (Refereed)
    Abstract [en]

    There has been extensive research and development activities in the field of nanofibrillated cellulose (NFC) materials during recent years, although microfibrillated cellulose was developed already during the late 1970s at ITT-Rayonier in USA. A major impediment for the large-scale use of NFC has been the high-energy use (excess of 30000 kWh/ton NFC in energy consumption). This problem has now been alleviated by a series of different pre-treatment procedures of the fibres prior to the subsequent mechanical cell wall delamination. The focus in practical papermaking applications of NFC is in the reinforcement of paper/board materials (dry strength wet-end additive) and in barrier coating applications. The driving forces in these applications are resource and energy efficiency in papermaking and the vision of substituting fossil-based films with nanocellulose barriers. Nanocellulose has excellent oil, fat and oxygen barrier properties in the dry state, but the oxygen barrier properties deteriorate at high relative humidities and the approaches to alleviate the moisture sensitivity will be discussed. Today, there are many companies in the process of commercializing NFC and several of them have pilot plants/pre-commercial operations and are planning for up scaling. A pilot plant for the nominal production of 100 kg/day (dry based NFC) was also taken into operation at Innventia AB in 2010. The current contribution will highlight critical issues in the production of NFC and discuss various applications and hurdles to be overcome in order to make NFC production for paper/board based end-use applications viable.

  • 344.
    Lindström, Tom
    et al.
    RISE, STFI-Packforsk.
    Banke, K.
    RISE, STFI-Packforsk.
    Larsson, Per Tomas
    RISE, STFI-Packforsk.
    Glad-Nordmark, Gunborg
    RISE, STFI-Packforsk.
    Boldizar, A.
    Nanoclay plating of cellulosic fiber surfaces2008In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 108, no 2, p. 887-891Article in journal (Refereed)
    Abstract [en]

    A basic problem in making cellulose-reinforced composites is achieving a dispersion of cellulosic fibers in an often olephinic polymer matrix. Drying cellulosic fibers results in the formation of fiber flocs/nodules because of their strong interfiber bonding, and this makes the hydrophilic cellulosic fibers difficult to disperse in a hydrophobic matrix material. One common approach to alleviate floe formation is to adsorb cationic surfactant onto anionically charged cellulose, which reduces the interfiber bonding, decreases floe formation and gives better compatibility with the matrix. In this report, a different approach is taken, namely to adsorb nanoclays onto the cellulosic fibers, and thereby reduce the natural hydrogen-bonding affinity between fibers. In a second report, the same technology will be shown to be advantageous to decrease floe formation in oleophinic composites reinforced with cellulosic fibers. This article summarizes experiments aimed at optimizing the chemistry of deposition of montmorillonite clay onto fiber surfaces. The aim was to optimize the chemical conditions for the heterodeposition of the anionic clay onto cationically charged fluff pulp. The experiments were designed to provide a theoretical framework for the deposition of the nanoclay onto the pulp fibers. High Mw p-DADMAC and an exfoliated clay (achieved by passing the clay through a homogenizer) were used. As expected, a certain degree of charge overcompensation by adding an electrolyte was necessary to bring about deposition. The adsorbed amount of clay could be calculated from the charge balance between the overcompensated charge and the net clay charge, constituting the theoretical framework for nanoclay heterodeposition. As expected, montmorillonite clay greatly destroyed the joint strength between fibers (determined by evaluating the strength of paper made from treated fibers). The surface coverage (determined by ESCA) was shown to be a linear function of the attached amount of clay, and ∌3% clay was required to fully cover the fiber surfaces. © 2008 Wiley Periodicals, Inc.

  • 345.
    Lindström, Tom
    et al.
    RISE, Innventia.
    Fellers, Christer
    RISE, Innventia.
    Ankerfors, Mikael
    BillerudKorsnäs AB, Sweden.
    Glad Nordmark, Gunborg
    RISE, Innventia.
    On the nature of joint strength of paper: Effect of dry strength agents - Revisiting the Page equation2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 459-468Article in journal (Refereed)
    Abstract [en]

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

  • 346.
    Lindström, Tom
    et al.
    RISE, Innventia.
    Fellers, Christer
    RISE, Innventia.
    Ankerfors, Mikael
    RISE, Innventia.
    Glad Nordmark, Gunborg
    RISE, Innventia.
    The effects of various chemical treatments on fibre-fibre joint strength in paper2012Conference paper (Refereed)
  • 347.
    Lindström, Tom
    et al.
    RISE, STFI-Packforsk.
    Larsson, Per Tomas
    RISE, STFI-Packforsk.
    Alkyl ketene dimer (AKD) sizing: A review2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 2, p. 202-209Article in journal (Refereed)
    Abstract [en]

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

  • 348.
    Lindström, Tom
    et al.
    RISE, Innventia.
    Naderi, Ali
    RISE, Innventia.
    Wiberg, Anna
    RISE, Innventia.
    Large scale applications of nanocellulosic materials: A comprehensive review2015In: Palpu Chongi Gisul/Journal of Korea Technical Association of the Pulp and Paper Industry, Vol. 47, no 6, p. 5-21Article in journal (Other academic)
  • 349.
    Lindström, Tom S. C.
    et al.
    RISE Research Institutes of Sweden. KTH Royal Institute of Technology, Sweden.
    Glad-Nordmark, Gunborg
    RISE Research Institutes of Sweden.
    Novel bulking technologies for cellulose fibres2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 1, p. 25-41Article in journal (Refereed)
    Abstract [en]

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

  • 350.
    Lindström, Tom S. C.
    et al.
    RISE Research Institutes of Sweden. KTH Royal Institute of Technology, sweden.
    Ström, Göran
    RISE Research Institutes of Sweden.
    Bulking of cellulose fibres - A review2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 1, p. 192-204Article, review/survey (Other academic)
    Abstract [en]

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

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