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  • 151.
    Krusper, Aleksandra
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Isaksson, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Gradin, Per A
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Modelling of out-of-plane compression loading of corrugated paper board structures2007In: Journal of engineering mechanics, ISSN 0733-9399, E-ISSN 1943-7889, Vol. 133, no 11, p. 1171-1177Article in journal (Refereed)
    Abstract [en]

    A simple analytical model for calculating the nonlinear deformations of a corrugated core (fluting) during out-of-plane compression is developed. The results from the analytical model are compared to a more comprehensive finite-element model and to experiments. A connection between the boundary conditions and the damage state of the corrugated board is discussed. Including a modified set of boundary conditions gives an almost perfect match of the initial stiffness to the experimental results, indicating that the core might be significantly damaged as a result of the manufacturing process. Possibly, the strength of corrugated boards might be increased about 20% if one could avoid damaging the fluting during the manufacturing process.

  • 152.
    Kulachenko, Artem
    et al.
    Royal Inst Technol, Dept Solid Mech, S-10044 Stockholm, Sweden.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Direct simulations of fiber network deformation and failure2012In: Mechanics of materials, ISSN 0167-6636, E-ISSN 1872-7743, Vol. 51, p. 1-14Article in journal (Refereed)
    Abstract [en]

    A finite element model for 3D random fiber networks was constructed to simulate deformation and failure behavior of networks with dynamic bonding/debonding properties. Such fiber networks are ubiquitous among many living systems, soft matters, bio-materials, and engineering materials (papers and non-woven). A key feature of this new network model is the fiber-fiber interaction model that is based on AFM measurements from our earlier study. A series of simulations have been performed to investigate strain localization behavior, strength statistics, in particular, the variations of strength, strain-to-failure and elastic modulus, and their size dependence. Other variables investigated are fiber geometries. The result showed that, in spite of its disordered structure, strength and elastic modulus of a fiber network varied very little statistically, as long as the average number of fibers in the simulated specimen and the degree of fiber orientation are kept constant. However, strain-to-failure showed very significant statistical variations, and thus more sensitivity to the disordered structures. (C) 2012 Elsevier Ltd. All rights reserved.

  • 153. Kulachenko, Artem
    et al.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Simulation of Wet Fibre Network Deformation2010Conference paper (Other academic)
  • 154.
    Larsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Mapping of Wood Supply Chains: a Case Study2015Conference paper (Refereed)
  • 155.
    Li, Xiaotian
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Schön, Thomas
    Atlas Industrial Print i Motala AB.
    A Paper-Based Screen Printed HF RFID Reader Antenna System2018In: IEEE Journal of Radio Frequency Identification, ISSN 2469-729X, Vol. 2, no 3, p. 118-126Article in journal (Refereed)
    Abstract [en]

    Screen printing is a stencil process where conductive inks are patterned onto substrates through a fine mesh of threads. Nowadays, screen printing can be used to print RFID antenna structures onto flexible and ultra-low-cost substrates such as pa-per. In this manuscript, we present an HF RFID reader antenna system, operating at 13.56 MHz, using screen printed Ag particle ink as conductor and using HP photo paper as substrate. The proposed antenna system comprises four loop antenna elements, matched to 50 Ω, and one I2C addressed SP4T multiplexer circuitry, controlled through an exterior embedded system. The geometries, designs and characterizations of the antenna system are described in the manuscript in details. Measurement results show that the antenna system has low power reflections and a suitable Q factor. It has a maximum 11.1 cm RFID tag read range at an antenna system input power of 33 dBm. 2D RFID tag positioning can be enabled by utilizing the RFID tag interrogation zones formed by the four loop antenna elements. In addition, a parametric study is carried out to investigate the effect of loop antenna element DC resistance on the antenna element performance. It can be concluded that the proposed method can be used to create low-cost and large-area HF RFID reader antenna systems.

  • 156.
    Linder, Tomas
    et al.
    Department of Computer Science, Electrical and Space Engineering Luleå University of Technology.
    Löfqvist, Torbjörn
    Department of Computer Science, Electrical and Space Engineering Luleå University of Technology.
    Gustafsson Coppel, Ludovic
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Neuman, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Edström, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lateral light scattering in fibrous media2013In: Optics Express, E-ISSN 1094-4087, Vol. 21, no 6, p. 7835-7840Article in journal (Refereed)
    Abstract [en]

    Lateral light scattering in fibrous media is investigated by computing the modulation transfer function (MTF) of 22 paper samples using a Monte Carlo model. The simulation tool uses phase functions from infinitely long homogenous cylinders and the directional inhomogeneity of paper is achieved by aligning the cylinders in the plane. The inverse frequency at half maximum of the MTF is compared to both measurements and previous simulations with isotropic and strongly forward single scattering phase functions. It is found that the conical scattering by cylinders enhances the lateral scattering and therefore predicts a larger extent of lateral light scattering than models using rotationally invariant single scattering phase functions. However, it does not fully reach the levels of lateral scattering observed in measurements. It is argued that the hollow lumen of a wood fiber or dependent scattering effects must be considered for a complete description of lateral light scattering in paper.

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    Linder_Lateral_light_scattering
  • 157.
    Lindström, Stefan B
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Amjad, R.
    Gåhlin, E.
    Andersson, L.
    Kaarto, M.
    Liubytska, Kateryna
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-). Kharkiv Polytechnic Institute.
    Persson, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Berg, Jan-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Nilsson, Fritjof
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-). KTH.
    Pulp Particle Classification Based on Optical Fiber Analysis and Machine Learning Techniques2024In: Fibers, ISSN 2079-6439, Vol. 12, no 1, article id 2Article in journal (Refereed)
    Abstract [en]

    In the pulp and paper industry, pulp testing is typically a labor-intensive process performed on hand-made laboratory sheets. Online quality control by automated image analysis and machine learning (ML) could provide a consistent, fast and cost-efficient alternative. In this study, four different supervised ML techniques—Lasso regression, support vector machine (SVM), feed-forward neural networks (FFNN), and recurrent neural networks (RNN)—were applied to fiber data obtained from fiber suspension micrographs analyzed by two separate image analysis software. With the built-in software of a commercial fiber analyzer optimized for speed, the maximum accuracy of 81% was achieved using the FFNN algorithm with Yeo–Johnson preprocessing. With an in-house algorithm adapted for ML by an extended set of particle attributes, a maximum accuracy of 96% was achieved with Lasso regression. A parameter capturing the average intensity of the particle in the micrograph, only available from the latter software, has a particularly strong predictive capability. The high accuracy and sensitivity of the ML results indicate that such a strategy could be very useful for quality control of fiber dispersions. 

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  • 158.
    Logenius, Louise
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Friman, Linda
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Agnemo, Roland
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    The influence of temperature and moisture on the optical properties of cellulose in the presence of metal chlorides and glucuronic acid2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 1, p. 72-80Article in journal (Refereed)
    Abstract [en]

    The influence of Mg2+, Ca2+, Fe3+ ions and glucuronic acid on the dry and humid heat-induced (120180C) discoloration of cotton linter sheets was investigated. The quantity of the added metal ions was similar to that of metal ions found in wood and pulp. Heat-induced ageing (120150C, pH 5) under dry conditions caused only slight discoloration of the reference sheets and of the sheets impregnated with the metal ions. However, during ageing at 180C, the presence of Mg2+ ions accelerated the discoloration. An initial pH in the range of 38 had no great influence on the discoloration of the reference sheets, but a low pH in combination with Mg2+ ions increased the discoloration drastically. Under humid ageing conditions at 180C (<30 min), the sheets discolored approximately twice as much as under dry conditions; the difference in discoloration caused by the metal ions was less than in dry ageing. Adding glucuronic acid to the sheets caused extensive discoloration under dry ageing conditions (120180°C), while Ca2+ and Mg2+ ions decreased the glucuronic acid induced discoloration. Under humid conditions (180°C), however, Mg2+ and Ca2+ ions did not prevent the discoloration caused by glucuronic acid. An increase in the absorption coefficient was observed at 285 nm, most likely due to the formation of 5-hydroxy-2-methyl-furaldehyde (HMF) and 2-furaldehyde (furfural). GC-MS analysis reveals increased formation of HMF in the sheets impregnated with Mg2+ ions. Degradation of the cellulose in which the alkaline earth metals act as Lewis acids is proposed.

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    FULLTEXT01
  • 159.
    Lundberg, Mathias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. PulpEye AB.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Crill Measurements For Improved Fines Material Control2018In: IMPC 2018, Trondheim, Norway, 2018Conference paper (Refereed)
    Abstract [en]

    Finding the characterization method that best matches the pulping process is crucial in enabling the monitoring and control of pulp and final-product properties. Control of optimal process parameters in the production line are thus dependent on reliable and valid results. The Crill method is an analogue method based on the relationship between the interactions of lights of two different wavelengths (UV and IR) with the particles in the pulp. By comparing the specific UV and IR surfaces, the crill value is calculated. The crill method has been used in two studies with the aims to validate the crill measurement in a high yield pulping (HYP) process by focusing on refining and control of crill value of different pulp streams. The results indicate that the crill method can be used to monitor fibre treatment in refining processes. Moreover, by controlling pulp streams with regards to crill value, improvements of pulp strength and retention on the paper machine (PM) can be achieved.

  • 160. Magalhães, S.
    et al.
    Fernandes, C.
    Pedrosa, J. F. S.
    Alves, L.
    Medronho, Bruno
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-). Universidade do Algarve, Faculdade de Ciências e Tecnologia, Campus de Gambelas, Faro, Portugal.
    Ferreira, P. J. T.
    Rasteiro, M. D. G.
    Eco-Friendly Methods for Extraction and Modification of Cellulose: An Overview2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 14, article id 3138Article, review/survey (Refereed)
    Abstract [en]

    Cellulose is the most abundant renewable polymer on Earth and can be obtained from several different sources, such as trees, grass, or biomass residues. However, one of the issues is that not all the fractionation processes are eco-friendly and are essentially based on cooking the lignocellulose feedstock in a harsh chemical mixture, such as NaOH + Na2S, and water, to break loose fibers. In the last few years, new sustainable fractionation processes have been developed that enable the obtaining of cellulose fibers in a more eco-friendly way. As a raw material, cellulose’s use is widely known and established in many areas. Additionally, its products/derivatives are recognized to have a far better environmental impact than fossil-based materials. Examples are textiles and packaging, where forest-based fibers may contribute to renewable and biodegradable substitutes for common synthetic materials and plastics. In this review, some of the main structural characteristics and properties of cellulose, recent green extraction methods/strategies, chemical modification, and applications of cellulose derivatives are discussed. 

  • 161. Massih, Ali R
    et al.
    Isaksson, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Ståhle, Per
    Modelling the behaviour of a control-element blade during irradiation1997In: Computers & Structures, 1997, Vol. 64, no 5/6, p. 1113-1127Conference paper (Refereed)
    Abstract [en]

    The control-rod elements in a boiling-water reactor contain natural boron carbide (B4C) powder, used as neutron-absorber material and clad in stainless-steel blades. During in-reactor service, the internal production of helium gas and point defects in neutron-irradiated boron carbide cause swelling which can induce significant contact stresses in the blade causing, eventually, stress-corrosion cracking of the blades. In this work, a finite-element analysis of a control-rod blade consisting of B4C powder and stainless-steel cladding has been performed using ADINA. An algorithm for the finite-element calculation of a porous material such as B4C powder has been developed and which models both swelling and consolidation behaviour of B4C powder. The Drucker-Prager constitutive law has been used to model the consolidation effect. The model has been verified with an analytical solution for a simple geometry. A number of cases with B4C powder in contact with stainless steel and using the actual blade design have been studied for which contact stresses, the displacements and the effective stresses are calculated. Finally, the model has been used to predict the deformation of the blade during irradiation under B4C swelling and irradiation-induced creep of stainless steel.

  • 162.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Joelsson, Tove
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. MoRe Research Örnsköldsvik AB.
    Miettinen, A.
    Ketoja, Jukka A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. VTT Technical Research Centre of Finland.
    Pettersson, Gunilla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Lignin inter-diffusion underlying improved mechanical performance of hot-pressed paper webs2021In: Polymers, E-ISSN 2073-4360, Vol. 13, no 15, article id 2485Article in journal (Refereed)
    Abstract [en]

    Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing temperature of 270 °C. The stronger bonding of wet fibres can be explained by the inter-diffusion of lignin macromolecules with an activation energy around 26 kJ mol−1 after lignin softening. The associated exponential acceleration of diffusion with temperature dominates over other factors such as process dynamics or final material density in setting wet strength. The optimum pressing temperature for dry strength is generally lower, around 200 °C, beyond which hemicellulose degradation begins. By varying the solids content prior to hot-pressing for the TMP sheets, the highest wet strength is achieved for the completely dry web, while no strong correlation was observed for the dry strength. 

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  • 163.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Joelsson, Tove
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-). MoRe Research Örnsköldsvik AB.
    Pettersson, Gunilla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Ketoja, Jukka
    Mid Sweden University, Faculty of Science, Technology and Media. VTT Technical Research Centre of Finland Ltd..
    Mietinen, Arttu
    University of Jyvaskyla; VTT Technical Research Centre of Finland Ltd.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Lignin Inter-Diffusion Underlying Improved Mechanical Performance of Hot-Pressed Paper Webs2023In: Mechanical Performance of Sustainable Bio-Based Compounds / [ed] Domenico Acierno and Antonella Patti, Basel: MDPI, 2023, p. 213-228Chapter in book (Refereed)
    Abstract [en]

    Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing temperature of 270 ◦C. The stronger bonding of wet fibres can be explained by the inter-diffusion of lignin macromolecules with an activation energy around 26 kJ mol−1 after lignin softening. The associated exponential acceleration of diffusion with temperature dominates over other factors such as process dynamics or final material density in setting wet strength. The optimum pressing temperature for dry strength is generally lower, around 200 ◦C, beyond which hemicellulose degradation begins. By varying the solids content prior to hot-pressing for the TMP sheets, the highest wet strength is achieved for the completely dry web, while no strong correlation was observed for the dry strength.

  • 164.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Characterisation of time-dependent, stochastic failure of fibre-based materials2015Conference paper (Refereed)
  • 165.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Predicting Stochastic Failure of Fibre-based Materials in Long Term and Short Term2014Conference paper (Other academic)
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  • 166.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Time-dependent statistical failure of fiber networks2015In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 92, no 4, article id 042158Article in journal (Refereed)
    Abstract [en]

    Numerical simulations of time-dependent stochastic failure of fiber network have been performed by using a central-force, triangular lattice model. This two-dimensional (2D) network can be seen as the next level of structural hierarchy to fiber bundles, which have been investigated for many years both theoretically and numerically. Unlike fiber bundle models, the load sharing of the fiber network is determined by the network mechanics rather than a preassigned rule, and its failure is defined as the point of avalanche rather than the total fiber failure. We have assumed that the fiber in the network follows Coleman’s probabilistic failure law [B. D. Coleman, J. Appl. Phys. 29, 968 (1958)] with the Weibull shape parameter β = 1 (memory less fiber). Our interests are how the fiber-level probabilistic failure law is transformed into the one for the network and how the failure characteristics and disorders on the fiber level influence the network failure response. The simulation results showed that, with increasing the size of the network (N), weakest-link scaling (WLS) appeared and each lifetime distribution at a given size approximately followed Weibull distribution. However, the scaling behavior of the mean and the Weibull shape parameter clearly deviate from what we can predict from the WLS of Weibull distribution. We have found that a characteristic distribution function has, in fact, a double exponential form, not Weibull form. Accordingly, for the 2D network system, Coleman’s probabilistic failure law holds but only approximately. Comparing the fiber and network failure properties, we found that the network structure induces an increase of the load sensitivity factor ρ (more brittle than fiber) and Weibull shape parameter β (less uncertainty of lifetime). Superimposed disorders on the fiber level reduce all these properties for the network. 

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  • 167.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Time-dependent, statistical failure of paperboard in compression2013In: Advances in pulp and paper research, Cambridge 2013, UK: Pulp and Paper Fundamental Research Society , 2013Conference paper (Refereed)
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    Statistical failure
  • 168.
    Mattsson, Amanda
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Uesaka, Tetsu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Time-Dependent Stochastic Failure of Fibre Network2014Conference paper (Other academic)
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  • 169.
    Melro, Elodie
    et al.
    Univ Coimbra, CQC, Dept Chem, Rua Larga, P-3004535 Coimbra, Portugal..
    Filipe, Alexandra
    Univ Coimbra, Dept Chem Engn, CIEPQPF, Polo 2 R Silvio Lima, P-3030790 Coimbra, Portugal..
    Sousa, Dora
    c5Lab, Edificio Cent Pk,Rua Cent Pk 6, P-2795242 Linda A Velha, Portugal..
    Medronho, Bruno
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Univ Algarve, Fac Ciencias & Tecnol, MED Mediterranean Inst Agr Environm & Dev, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal.
    Romano, Anabela
    Univ Algarve, Fac Ciencias & Tecnol, MED Mediterranean Inst Agr Environm & Dev, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal..
    Revisiting lignin: a tour through its structural features, characterization methods and applications2021In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 45, no 16, p. 6986-7013Article, review/survey (Refereed)
    Abstract [en]

    Lignin is a complex organic polymer found in the plant cell wall with important biological functions, such as water transport, mechanical support, and resistance to various stresses. It is considered the second most abundant biopolymer on earth and the largest natural source of aromatics. Despite being annually co-produced in massive amounts, during cellulose fragmentation in the pulp industry and ethanol biorefinery, it is clearly undervalued; most of it is discarded or burned as fuel for energy production and, so far, only ca. 1-2% of lignin has been utilized as a high-value product. This underuse makes lignin the future resource of choice to produce green fuels and a wide range of added-value biomaterials and chemicals, which can contribute to the transition to more sustainable industries. However, its great variability between plant families combined with its complex and chemically inert structure is challenging researchers who seek for strategies regarding its valorization. With this scope, several different approaches have emerged regarding the development of better and efficient isolation methods, purification and characterization techniques, and improved methodologies for lignin chemical modification and blending with other compounds. These improvements represent important opportunities for the creation of value-added lignin-based biopolymers and materials and some have already shown potential to be scaled up. All these aspects are pedagogically introduced and discussed in this review.

  • 170.
    Melro, Elodie
    et al.
    University of Coimbra, CQC, Department of Chemistry, Rua Larga, Coimbra, Portugal.
    Valente, Artur J. M.
    University of Coimbra, CQC, Department of Chemistry, Rua Larga, Coimbra, Portugal.
    Antunes, Filipe E.
    University of Coimbra, CQC, Department of Chemistry, Rua Larga, Coimbra, Portugal.
    Romano, Anabela
    Universidade do Algarve, Faro, Portugal.
    Medronho, Bruno
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Universidade do Algarve, Faro, Portugal.
    Enhancing lignin dissolution and extraction: The effect of surfactants2021In: Polymers, E-ISSN 2073-4360, Vol. 13, no 5, article id 714Article in journal (Refereed)
    Abstract [en]

    The dissolution and extraction of lignin from biomass represents a great challenge due to the complex structure of this natural phenolic biopolymer. In this work, several surfactants (i.e., non-ionic, anionic, and cationic) were used as additives to enhance the dissolution efficiency of model lignin (kraft) and to boost lignin extraction from pine sawdust residues. To the best of our knowledge, cationic surfactants have never been systematically used for lignin dissolution. It was found that ca. 20 wt.% of kraft lignin is completely solubilized using 1 mol L−1 octyltrimethylammo-nium bromide aqueous solution. A remarkable dissolution efficiency was also obtained using 0.5 mol L−1 polysorbate 20. Furthermore, all surfactants used increased the lignin extraction with formic acid, even at low concentrations, such as 0.01 and 0.1 mol L−1. Higher concentrations of cationic surfactants improve the extraction yield but the purity of extracted lignin decreases. 

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  • 171.
    Moilanen, Carolina S.
    et al.
    Department of Mechanical Engineering and Industrial Systems, Tampere University of Technology.
    Björkqvist, Tomas
    Department of Automation Science and Engineering, Tampere University of Technology.
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Salminen, Lauri I.
    A Fredrikson Research & Consulting Ltd., Vähäkuja 2 A 2, Jyväskylä, Finland.
    Saarenrinne, Pentti
    Department of Mechanical Engineering and Industrial Systems, Tampere University of Technology, Finland.
    High strain rate radial compression of Norway spruce earlywood and latewood2016In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 1, p. 873-889Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of Norway spruce were studied and a compression model for mechanical pulping was developed. The split-Hopkinson pressure bar technique was combined with high-speed photography to analyse local radial compression. Data analysis focussed on the differences between mechanical properties of earlywood and latewood. Measurements were conducted at both room temperature and 135 C. The effect of prefatigue treatment was also studied. A simple material model was defined linearly in parts and fitted to the measurement data to quantify the differences. New results were found on the differences in inelastic behaviour of earlywood and latewood at large deformations. In addition, other results were in line with previously published results.

  • 172.
    Moser, Carl
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Energy efficiency for cellulose nanfiber (CNF) production2015In: Cellulose Materials Doctoral Students Summer Conference 2015, 2015Conference paper (Refereed)
  • 173.
    Moser, Carl
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Xyloglucan Adsorption as a Method to Measure Surface Area for Never Dried Cellulose Nanofibers2017Conference paper (Refereed)
  • 174.
    Moser, Carl
    et al.
    KTH Royal Institute of Technology; Valmet AB.
    Henriksson, Gunnar
    KTH Royal Institute of Technology.
    Lindström, Mikael E.
    KTH Royal Institute of Technology.
    Specific Surface Area Increase during Cellulose Nanofiber Manufacturing Related to Energy Input2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 3, p. 7124-7132Article in journal (Refereed)
    Abstract [en]

    Softwood fibers pretreated with a monocomponent endoglucanase wereused to prepare a series of cellulose nanofiber qualities using amicrofluidizer and 2 to 34 MWh ton-1 of energy input. The specific surfacearea was determined for the series using critical point drying and gasadsorption. Although the specific surface area reached a maximum of 430m2 g-1 at 11 MWh ton-1, the nanofiber yield and transmittance continued toincrease beyond this point, indicating that more energy is required toovercome possible friction caused by an interwoven nanofiber networkunrelated to the specific surface area. A new method for estimating thesurface area was investigated using xyloglucan adsorption in pure water.With this method it was possible to follow the disintegration past the pointof maximum specific surface area. The technical significance of thesefindings is discussed.

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  • 175. Möller, Klaus
    et al.
    Nikko, Airi
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The effect of multiple recycling on newsprint quality: a large-scale pilot study, performed 1992 -19962002In: PTS-CTP Symposium on Deinking Technology, 22-24 April 2002 Munich Germany, 2002Conference paper (Other academic)
  • 176. Nanri, Yasunori
    et al.
    Uesaka, Tetsu
    Paper & Board Quality Division, Pulp and Paper Research Institute of Canada.
    DIMENSIONAL STABILITY OF MECHANICAL PULPS - DRYING SHRINKAGE AND HYGROEXPANSIVITY1993In: TAPPI Journal, ISSN 0734-1415, Vol. 76, no 6, p. 62-66Article in journal (Refereed)
  • 177. Negro, Carlos
    et al.
    Pettersson, Gunilla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Mattsson, Amanda
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Nyström, Staffan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Sanchez-Salvador, Jose Luis
    Blanco, Angeles
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Synergies between Fibrillated Nanocellulose and Hot-Pressing of Papers Obtained from High-Yield Pulp2023In: Nanomaterials, E-ISSN 2079-4991, Vol. 13, no 13, article id 1931Article in journal (Refereed)
    Abstract [en]

    To extend the application of cost-effective high-yield pulps in packaging, strength and barrier properties are improved by advanced-strength additives or by hot-pressing. The aim of this study is to assess the synergic effects between the two approaches by using nanocellulose as a bulk additive, and by hot-pressing technology. Due to the synergic effect, dry strength increases by 118% while individual improvements are 31% by nanocellulose and 92% by hot-pressing. This effect is higher for mechanical fibrillated cellulose. After hot-pressing, all papers retain more than 22% of their dry strength. Hot-pressing greatly increases the paper’s ability to withstand compressive forces applied in short periods of time by 84%, with a further 30% increase due to the synergic effect of the fibrillated nanocellulose. Hot-pressing and the fibrillated cellulose greatly decrease air permeability (80% and 68%, respectively) for refining pretreated samples, due to the increased fiber flexibility, which increase up to 90% using the combined effect. The tear index increases with the addition of nanocellulose, but this effect is lost after hot-pressing. In general, fibrillation degree has a small effect which means that low- cost nanocellulose could be used in hot-pressed papers, providing products with a good strength and barrier capacity. 

  • 178.
    Neuman, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Gustafsson Coppel, Ludovic
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Edström, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    A partial explanation of the dependence between light scattering and light absorption in the Kubelka-Munk model2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 426-430Article in journal (Refereed)
    Abstract [en]

    The Kubelka-Munk scattering and absorption coefficients of a set of paper samples are assessed using reflectance measurements in d/0 geometry. The coefficients display the widely studied dependence between light scattering and light absorption, since the light scattering coefficient decreases in regions of high absorption. It is shown using general radiative transfer theory that part of this dependence can be explained and eliminated by taking into account the geometry of the d/0 instrument and the single scattering anisotropy, thus capturing the angular variations of the light reflected from the samples. These findings allow the papermaker to better predict the reflectance from mixtures of pulps, fillers, dye, and FWA, and to better evaluate bleaching efforts. 

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    Neuman_A_partial_explanation
  • 179.
    Niga, Petru
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Örtegren, Jonas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Alecrim, Viviane
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Klaman, Marianne
    Innventia AB, Stockholm, Sweden.
    Blohm, Erik
    Innventia AB, Stockholm, Sweden.
    Lofthus, Jon
    Innventia AB, Stockholm, Sweden.
    Hybrid printing: paper media for combined flexographic and inkjet printing2012In: Conference proceedings International Paper Physics Conference, Stockholm: Innventia , 2012, p. 79-81Conference paper (Other academic)
    Abstract [en]

    Hybrid printing combining inkjet technology with flexography can be used to add customer specific information into the production of packaging and print. However, in order to improve print quality, a comprehensive understanding of the mechanisms governing print quality is required. In this work, inkjet printing using three aqueous inkjet inks was performed on top of flexographic printouts on four paper substrates. For comparative reasons, inkjet printouts were made on the four papers as well. The flexographic film contained tone values ranging from 0 to 100% ink coverage. Line width and print density of the inkjet printouts were evaluated. It was found that paper characteristics such as surface energy, porosity, absorption coefficient and surface roughness play an important role in defining the final print quality. These findings are further supported by micrograph images.

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    fulltext
  • 180.
    Niskanen, Ilpo
    et al.
    University of Oulu, Oulu, Finland.
    Forsberg, Viviane
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. KTH, Stockholm.
    Zakrisson, Daniel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Engberg, Birgitta A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Heikkilä, Rauno
    University of Oulu, Oulu, Finland.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Determination of relative solids concentration in homogeneous dual component pulp-filler suspension by multi-spectrophotometer2020In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 35, no 1, p. 71-77Article in journal (Refereed)
    Abstract [en]

    The concentration of fibers and fillers in the pulp suspension is an important parameter in the monitoring process. This paper proposes a versatile optical measurement system to estimate the concentration of a solids mixture in water. The geometry used in a multi-spectrophotometer (MSM) enables the controlled observation of transmission, and forward scattering light from the suspension in the UV-visible spectral range. We have developed the new fibers mixing system which gives a homogenous distribution of the fines and fillers making it possible to increase the reproducibility and accuracy of the measurement. The data analysis is based on the Beer-Lambert law and CIELAB color space equations. The results show that the proposed method is accurate for measuring the fines and filler concentrations in multicomponent suspensions. 

  • 181.
    Niskanen, Kaarlo
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Mechanics of paper products2012Collection (editor) (Other academic)
    Abstract [en]

    This graduate level textbook focuses on the mechanical properties and performance of products made of fiber-based materials such as paper and board. The book aims to help students develop effective skills for solving problems of product performance and engineering challenges in new product development. Therefore the material is organized with a problem-based approach - a practical example of product performance is presented and then the relevant mechanics are analyzed to deduce which material properties control the performance.

  • 182.
    Niskanen, Kaarlo
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Östlund, Sören
    The challenge2021In: Mechanics of Paper Products, Walter de Gruyter, 2021, p. 1-3Chapter in book (Other academic)
  • 183.
    Nordin, Lisa
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Bäck, Roland
    SCA R&D Centre.
    Ferritsius, Olof
    Pöyry Sweden AB.
    Ferritsius, Rita
    Pöyry Sweden AB.
    Sandberg, Christer
    Holmen Paper Development Centre.
    Sundvall, Öjvind
    Eurocon Analyzer AB.
    Analysis of the quality of optical fibre and fines measurement for prediction of dewatering characteristics for mechanical pulpsManuscript (Other academic)
    Abstract [en]

    The quality of the optical fibre and fines measurement has been investigated. Fibres and fines of different quality were mixed in defined proportions and the mixtures were characterized by means of optical fibre measurements and dewatering behaviour. The results show that the same measured fines amounts show different dewatering behaviour, depending on the quality of the fines used. The difference in fines quality was, however, not reflected in the optical measurement. We conclude that this is caused by too low resolution in the optical measurement, so there is a large need for higher resolution of the measurement equipments in order to make it possible to measure the shape of the fines.

  • 184.
    Nordin, Lisa
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Bäck, Roland
    SCA R&D Center.
    Ferritsius, Olof
    Pöyry.
    Sandberg, Christer
    Holmen Paper Development Centre.
    Measurement and prediction of dewatering characteristics for mechanical pulps using optical fibre analyzers2009In: Proceedings - 2009 International Mechanical Pulping Conference, IMPC 2009, 2009, p. 309-316Conference paper (Refereed)
    Abstract [en]

    The aim of this work was to obtain an on-line measurement for dewatering behaviour in the wire section based on fibre and fines characteristics. Four laboratory dewatering equipments were compared and the fibre characteristics were measured by means of optical fibre analyzers.

    The results show that rough correlations do appear to exist between the dewatering equipments; however they rank the pulps differently depending on the raw wood material used and whether the refining conditions are mild or harsh. The prediction models based on fibre characteristics showed a high degree of statistical accuracy. The descriptions, however, proved not to be sufficiently good with regards to the dewatering behaviour for them to be used in relation to on-line applications. This might have been because consideration was not given to some important variables which do, in fact, have a significant impact on the drainability. These variables could include physical fibre properties or others that are not measured, or properties that, at present, are unable to be measured at a sufficient resolution.

  • 185.
    Nordin, Lisa
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Sundvall, Öjvind
    Eurocon Analyzer AB.
    Characterization and classification of dewatering measurement techniques for mechanical pulps2008In: Proceedings of the PRS, Finland, May 2008., 2008Conference paper (Refereed)
  • 186.
    Nordin, Tommy
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. MoRe Research Örnsköldsvik AB.
    Svedberg, Anna
    MoRe Research Örnsköldsvik AB.
    Norgren, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Pettersson, Gunilla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Industrially Relevant In-situ Production Of High Yield Pulp Based Nanocellulose Materials Optimized To Improve Strength In Packaging And Printing Papers: A Comparison Between CMC And MFC As The Anionic Component In Layer-by-Layer Technology2018In: IMPC 2018, Trondheim, Norway, 2018Conference paper (Refereed)
    Abstract [en]

    A key issue in papermaking is to understand how to improve strength without losing other important quality measures, like paper bulk. This must of course also be done in a cost efficient way. The trials described in this paper show some different aspects related to the replacement of the expensive anionic component CMC (carboxymethylcellulose) often used in Layer-by-Layer technology together with cationic starch in order to improve strength properties as z-strength and tensile strength of typical chemi-thermomechanical pulp (CTMP) often used as dominating component in industrial scale paper board production. The replacement for CMC investigated here is a MFC (micro-fibrillated cellulose) as the anionic component and paper sheets has been produced on an experimental paper machine at MoRe Research AB. This MFC is a commercially available product and it has not been treated in ways of increasing charge density. The trials were performed at a small pilot scale experimental paper machine (XPM) at MoRe Research in Örnsköldsvik, Sweden. This XPM is equipped with a unique setup to perform Layer-by-Layer-tests under very well controlled conditions. The general conclusion is that it could, with further developments, be feasible to replace CMC with MFC to improve bonding in typical CTMP based paper sheets.

  • 187.
    Norgren, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Costa, Carolina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Alves, Luis
    Eivazi, Alireza
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Dahlström, Christina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Svanedal, Ida
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Medronho, Bruno
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-). Universidade do Algarve.
    Perspectives on the Lindman Hypothesis and Cellulose Interactions2023In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 28, no 10, article id 4216Article, review/survey (Refereed)
    Abstract [en]

    In the history of cellulose chemistry, hydrogen bonding has been the predominant explanation when discussing intermolecular interactions between cellulose polymers. This is the general consensus in scholarly textbooks and in many research articles, and it applies to several other biomacromolecules’ interactions as well. This rather unbalanced description of cellulose has likely impacted the development of materials based on the processing of cellulose—for example, via dissolution in various solvent systems and regeneration into solid materials, such as films and fibers, and even traditional wood fiber handling and papermaking. In this review, we take as a starting point the questioning of the general description of the nature of cellulose and cellulose interactions initiated by Professor Björn Lindman, based on generic physicochemical reasoning about surfactants and polymers. This dispute, which became known as “the Lindman hypothesis”, highlights the importance of hydrophobic interactions in cellulose systems and that cellulose is an amphiphilic polymer. This paper elaborates on Björn Lindman’s contribution to the subject, which has caused the scientific community to revisit cellulose and reconsider certain phenomena from other perspectives. 

  • 188.
    Norgren, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Effects of Reject Refining at High Temperature on TMP Fibre Properties2008Doctoral thesis, comprehensive summary (Other academic)
  • 189.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Gradin, P A
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Nyström, Staffan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Gullikson, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Investigation of the z-direction strength properties of paper by use of acoustic emission monitoring2008In: Journal of Acoustic Emission, ISSN 0730-0050, Vol. 26, p. 23-31Article in journal (Refereed)
  • 190.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Isaksson, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Acoustic emission monitoring to evaluate the z-direction and in-plane strength properties of TMP reject fractionManuscript (Other academic)
  • 191.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Nyström, Staffan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Gulliksson, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Investigation of the Z-direction strength properties of paper by use of acoustic emission monitoring2008In: 28th European conferance on acoustic emission testing, 2008, p. 238-243Conference paper (Other academic)
  • 192.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hoglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Consolidation of fibre-fibre bonds in TMP and CTMP based papers2014In: Paper Technology, ISSN 0958-6024, Vol. 55, no 3, p. 6-10Article in journal (Other academic)
    Abstract [en]

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

  • 193.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Irreversible long fibre collapse at high temperature refining in a TMP system: Effects on fibre and surface properties2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 1, p. 19-24Article in journal (Refereed)
    Abstract [en]

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

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    Norgren et al: Irreversible long fibre collapse at high temperature refining in a TMP system NPPRJ 2009 24 1 pp 19-24
  • 194.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Irreversible long fibre collapse at high temperure reject refining in at TMP system - Initial studies.2003In: Proceedings from IMPC 2003, Quebec city, 2003Conference paper (Other scientific)
    Abstract [en]

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

  • 195.
    Norgren, Sven
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Moisture-induced surface roughness in TMP sheets2008In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 34, no 3, p. 139-146Article in journal (Refereed)
    Abstract [en]

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

  • 196.
    Norlin, Börje
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-).
    An, Siwen
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-). Lund University, MAX IV Laboratory, SE-221 00 Lund, Sweden.
    Granfeldt, Thomas
    Valmet AB, Gustaf Gidlöfs väg 4, SE-851 79 Sundsvall, Sweden.
    Krapohl, David
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-).
    Lai, Barry
    Argonne National Laboratory, 9700 S. Cass. Avenue, Lemont, IL 60439, U.S.A..
    Rahman, Hafizur
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Zeeshan, Faisal
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-).
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Visualisation of sulphur on single fibre level for pulping industry2023In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 18, no 01, p. C01012-C01012Article in journal (Refereed)
    Abstract [en]

    In the pulp and paper industry, about 5 Mt/y chemithermomechanical pulp (CTMP) are produced globally from softwood chips for production of carton board grades. For tailor making CTMP for this purpose, wood chips are impregnated with aqueous sodium sulphite for sulphonation of the wood lignin. When lignin is sulphonated, the defibration of wood into pulp becomes more selective, resulting in enhanced pulp properties. On a microscopic fibre scale, however, one could strongly assume that the sulphonation of the wood structure is very uneven due to its macroscale size of wood chips. If this is the case and the sulphonation could be done significantly more evenly, the CTMP process could be more efficient and produce pulp even better suited for carton boards. Therefore, the present study aimed to develop a technique based on X-ray fluorescence microscopy imaging (µXRF) for quantifying the sulphur distribution on CTMP wood fibres. Firstly, the feasibility of µXRF imaging for sulphur homogeneity measurements in wood fibres needs investigation. Therefore, clarification of which spatial and spectral resolution that allows visualization of sulphur impregnation into single wood fibres is needed. Measurements of single fibre imaging were carried out at the Argonne National Laboratory’s Advanced Photon Source (APS) synchrotron facility. With a synchrotron beam using one micrometre scanning step, images of elemental mapping are acquired from CTMP samples diluted with non-sulphonated pulp under specified conditions. Since the measurements show significant differences between sulphonated and non-sulphonated fibres, and a significant peak concentration in the shell of the sulphonated fibres, the proposed technique is found to be feasible. The required spatial resolution of the µXRF imaging for an on-site CTMP sulphur homogeneity measurement setup is about 15 µm, and the homogeneity measured along the fibre shells is suggested to be used as the CTMP sulphonation measurement parameter.

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    fulltext
  • 197.
    Osong, Sinke Henshaw
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Development of nanofibrillated cellulose/nanographite composites for paper applications2015In: Cellulose Materials Doctoral Students Summer Conference 2015 / [ed] Hauhio, Leena, Aalto University, Finland, 2015Conference paper (Refereed)
  • 198. Pelton, R.
    et al.
    Zhang, J.
    Wågberg, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Rundlöf, Mats
    The role of surface polymer compatibility in the formation of fiber/fiber bonds in paper2000In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 15, no 5, p. 400-406Article in journal (Refereed)
    Abstract [en]

    The tensile strength of unbeaten kraft pulp handsheets was measured as a function of the compatibility of polymers adsorbed on the fibers. Two types of fibers were prepared, one was treated with slightly cationic dextran and the second was treated with slightly hydrophobic cationic dextran. The dextrans were chosen because both are paper strength enhancing polymers and yet they are incompatible with each other. Either dextran alone significantly enhanced paper strength whereas sheets made with mixtures were weaker. The results are interpreted in terms of the polymer compatibility. When a fiber/fiber bond forms between two surfaces bearing incompatible adsorbed polymers, the polymers will not interdiffuse during sheet consolidation thus giving a relatively weak interfiber bond.

  • 199.
    Perez, Alan D.
    et al.
    Univ Twente, Fac Sci & Technol, Sustainable Proc Technol Grp, Enschede, Netherlands..
    Fiskari, Juha
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Schuur, Boelo
    Univ Twente, Fac Sci & Technol, Sustainable Proc Technol Grp, Enschede, Netherlands..
    Delignification of Low-Energy Mechanical Pulp (Asplund Fibers) in a Deep Eutectic Solvent System of Choline Chloride and Lactic Acid2021In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 9, article id 688291Article in journal (Refereed)
    Abstract [en]

    Deep eutectic solvents (DESs) are considered as a green and environmentally benign solvent class for various applications, including delignification of biomass. One of the major challenges in the delignification of biomass by DES is attributed to the limitations in mass transfer. By subjecting wood chips to a low-energy mechanical refining, i.e., the Asplund process, the accessible surface area increases greatly, which in turn improves the mass transfer and increases the reaction rate. In this research, the DES delignification of Asplund fibers made of Norway spruce was studied as a strategy to produce papermaking fibers under mild conditions. A DES consisting of lactic acid and choline chloride was used due to its proven performance in delignification. Various operational conditions, such as temperature, time, DES-to-wood ratio, and the type of stirring were studied. A novel parameter, Q, allowed to evaluate the impact of the operational conditions on the quality of the pulp in terms of delignification degree and fiber length. The results showed that cooking temperature had the most significant effect on the pulp quality. Additionally, it was observed that cooking times between 30 and 45 min result in a pulp yield of about 50%, while fibers have a lignin content of about 14% and a fiber length of 0.6 mm. These results demonstrate that it is possible to obtain fibers of relatively good quality from DES delignification using Asplund fibers as the starting material.

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    fulltext
  • 200. Persson, Erik
    et al.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Karlsson, Lennart
    Nilsson, Fredrik
    Wahlgren, Mikael
    Utilization of the natural variations in wood properties in production of TMP: Comparison between pilot plant and mill scale trials using different assortments of Norway spruce pulpwood2003In: 2003 International Mechanical Pulping Conference / Pulp and Paper Technical Association of Canada: International Mechanical Pulping Conference ; (Quebec) : 2003.06.02-05, Montreal: PAPTAC , 2003, p. 485-Conference paper (Refereed)
    Abstract [en]

    International Mechanical Pulping Conference, Québec City Canada x-y June 2003, Persson, Erik., Engstrand, Per, Karlsson, Lennart., Nilsson, Fredrik, Wahlgren, Mikael.

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