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  • 1. Acciaro, R.
    et al.
    Aulin, C.
    RISE, Innventia.
    Wågberg, L.
    Lindström, T.
    RISE, Innventia.
    Claesson, P.M.
    Varga, I.
    Investigation of the formation structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels2011In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, no 4, p. 1369-1377Article in journal (Refereed)
  • 2.
    Adeboye, Peter Temitope
    et al.
    Chalmers University of Technology, Sweden.
    Bettiga, Maurizio
    Chalmers University of Technology, Sweden.
    Aldaeus, Fredrik
    RISE, Innventia.
    Larsson, Per Tomas
    RISE, Innventia.
    Olsson, Lars
    RISE, Innventia. Chalmers University of Technology, Sweden.
    Catabolism of coniferyl aldehyde, ferulic acid and p-coumaric acid by Saccharomyces cerevisiae yields less toxic products2015In: Microbial Cell Factories, E-ISSN 1475-2859, Vol. 14, no 1, article id 149Article in journal (Refereed)
    Abstract [en]

    Background: Lignocellulosic substrates and pulping process streams are of increasing relevance to biorefineries for second generation biofuels and biochemical production. They are known to be rich in sugars and inhibitors such as phenolic compounds, organic acids and furaldehydes. Phenolic compounds are a group of aromatic compounds known to be inhibitory to fermentative organisms. It is known that inhibition of Sacchromyces cerevisiae varies among phenolic compounds and the yeast is capable of in situ catabolic conversion and metabolism of some phenolic compounds. In an approach to engineer a S. cerevisiae strain with higher tolerance to phenolic inhibitors, we selectively investigated the metabolic conversion and physiological effects of coniferyl aldehyde, ferulic acid, and p-coumaric acid in Saccharomyces cerevisiae. Aerobic batch cultivations were separately performed with each of the three phenolic compounds. Conversion of each of the phenolic compounds was observed on time-based qualitative analysis of the culture broth to monitor various intermediate and final metabolites. Result: Coniferyl aldehyde was rapidly converted within the first 24 h, while ferulic acid and p-coumaric acid were more slowly converted over a period of 72 h. The conversion of the three phenolic compounds was observed to involved several transient intermediates that were concurrently formed and converted to other phenolic products. Although there were several conversion products formed from coniferyl aldehyde, ferulic acid and p-coumaric acid, the conversion products profile from the three compounds were similar. On the physiology of Saccharomyces cerevisiae, the maximum specific growth rates of the yeast was not affected in the presence of coniferyl aldehyde or ferulic acid, but it was significantly reduced in the presence of p-coumaric acid. The biomass yields on glucose were reduced to 73 and 54 % of the control in the presence of coniferyl aldehyde and ferulic acid, respectively, biomass yield increased to 127 % of the control in the presence of p-coumaric acid. Coniferyl aldehyde, ferulic acid and p-coumaric acid and their conversion products were screened for inhibition, the conversion products were less inhibitory than coniferyl aldehyde, ferulic acid and p-coumaric acid, indicating that the conversion of the three compounds by Saccharomyces cerevisiae was also a detoxification process. Conclusion: We conclude that the conversion of coniferyl aldehyde, ferulic acid and p-coumaric acid into less inhibitory compounds is a form of stress response and a detoxification process. We hypothesize that all phenolic compounds are converted by Saccharomyces cerevisiae using the same metabolic process. We suggest that the enhancement of the ability of S. cerevisiae to convert toxic phenolic compounds into less inhibitory compounds is a potent route to developing a S. cerevisiae with superior tolerance to phenolic compounds.

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  • 3. Agnihotri, S.
    et al.
    Johnsen, I.A.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Moe, S.
    Gregersen, Ø.
    More selective biorefining of softwood by combined hot water and ethanol organosolv pretreatment2011Conference paper (Refereed)
  • 4.
    Agnihotri, Swarnima
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Johnsen, Ingvild A.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Böe, Maren S.
    NTNU Norwegian University of Science and Technology, Norway.
    Öyaas, Karin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Moe, Størker
    NTNU Norwegian University of Science and Technology, Norway.
    Ethanol organosolv pretreatment of softwood (Picea abies) and sugarcane bagasse for biofuel and biorefinery applications2015In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 49, no 5, p. 881-896Article in journal (Refereed)
    Abstract [en]

    Ethanol derived from biomass has the potential to be a renewable transportation fuel that can replace gasoline. This work was carried out to establish an optimized ethanol organosolv pretreatment of Norway spruce (Picea abies) for bioethanol production (63 wt% EtOH, pH ~3.5 in aqueous phase, 170–240 °C, 90 min) utilizing hydrolytic enzymes in the saccharification step. To test the generality of the method, a series of ethanol organosolv pretreatments were also performed on sugarcane bagasse (50 wt% EtOH, pH ~3.5 in aqueous phase, 155–210 °C, 90–120 min). The degree of delignification increased with increasing temperature during pretreatment, and the fastest increase was observed with sugarcane bagasse. The pretreatments were carried out in a batch mode. The maximum degree of delignification of ~65 % was reached at ~235 °C for Norway spruce, while sugarcane bagasse reached ~80 % at ~210 °C. Cellulose was subjected to degradation (5–10 % points) at these temperatures. Subsequent enzymatic hydrolysis (30 FPU/g cellulose, 32 pNPGU/g cellulose, 50 °C, 48 h) of ethanol organosolv-pretreated biomass achieved complete conversion for both raw materials at the highest degrees of delignification.

  • 5. Ahlberg, C.
    et al.
    Lundell, F.
    Söderberg, L. Daniel
    RISE, Innventia.
    Self-organization of fibers in a suspension between two counter-rotating discs2009In: Proceedings of the ASME Fluids Engineering Division Summer Conference 2009, 2009, Vol. 1, no PART A, p. 585-592Conference paper (Refereed)
    Abstract [en]

    The behavior of fibers suspended in a flow between two flat counter-rotating discs has been studied experimentally. Captured images of the fibers in the flow were analyzed by steerable filters, to extract positions and orientations of the fibers. Experiments were performed for gaps between the discs of less than one fiber length, and for equal absolute values of the angular velocities for the discs. The length-to-diameter ratio of the fibers was approximately 14. During certain conditions, the fibers organized themselves in a distinct manner, which we will denote as fiber trains, in which three or more fibers are aligned next to each other, at the same radial position, with a short fiber-to-fiber distance. The direction of the individual fibers is radial and the direction of the whole train is tangential. Trains containing more than 60 fibers have been observed and are quite impressing.

  • 6.
    Ahlroth, Mikael
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Bialik, Marta
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Jansson, Mikael
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. Andritz, Sweden.
    Rosenqvist, Kristian
    ÅF, Sweden.
    Bark and wood powder firing in the recovery boiler for maximum power generation2017In: International chemical recovery conference, May 24-26, 2017, Halifax, Canada, PAPTAC , 2017Conference paper (Refereed)
    Abstract [en]

    The effect of co-firing bark or wood powder in a recovery boiler is studied. The effect of increased NPEs in the liquor and lime cycles, the FMT and sticky dust and the smelt composition is assessed by using simulation tools. The results indicate that generating an additional 22-39% HP steam for power production by firing wood powder in the recovery boiler is a viable option, if Cl and K are purged from the ESP dust by a treatment unit. The smelt is enriched with the same proportion of NPEs as the as-fired liquor.

  • 7.
    Ail, Ujwala
    et al.
    Linköpings Universitet, Sweden.
    Khan, Zia Ullah
    Linköpings Universitet, Sweden.
    Granberg, Hjalmar
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Berthold, Fredrik
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Parasuraman, Rajasekar
    Indian Institute of Science, India.
    Umarji, Arun M.
    Indian Institute of Science, India.
    Slettengren, Kerstin
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Pettersson, Henrik
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Crispin, Xavier
    Linköpings Universitet, Sweden.
    Room temperature synthesis of transition metal silicide-conducting polymer micro-composites for thermoelectric applications2017In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 225, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Organic polymer thermoelectrics (TE) as well as transition metal (TM) silicides are two thermoelectric class of materials of interest because they are composed of atomic elements of high abundance; which is a prerequisite for mass implementation of thermoelectric (TE) solutions for solar and waste heat recovery. But both materials have drawbacks when it comes to finding low-cost manufacturing. The metal silicide needs high temperature (>1000 °C) for creating TE legs in a device from solid powder, but it is easy to achieve long TE legs in this case. On the contrary, organic TEs are synthesized at low temperature from solution. However, it is difficult to form long legs or thick films because of their low solubility. In this work, we propose a novel method for the room temperature synthesis of TE composite containing the microparticles of chromium disilicide; CrSi2 (inorganic filler) in an organic matrix of nanofibrillated cellulose- poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (NFC-PEDOT:PSS). With this method, it is easy to create long TE legs in a room temperature process. The originality of the approach is the use of conducting polymer aerogel microparticles mixed with CrSi2 microparticles to obtain a composite solid at room temperature under pressure. We foresee that the method can be scaled up to fabricate and pattern TE modules. The composite has an electrical conductivity (σ) of 5.4 ± 0.5 S/cm and the Seebeck coefficient (α) of 88 ± 9 ΌV/K, power factor (α2σ) of 4 ± 1 ΌWm−1K−2 at room temperature. At a temperature difference of 32 °C, the output power/unit area drawn across the load, with the resistance same as the internal resistance of the device is 0.6 ± 0.1 ΌW/cm2.

  • 8.
    Alakalhunmaa, Suvi
    et al.
    University of Helsinki, Finland.
    Parikka, Kristi
    University of Helsinki, Finland.
    Penttilä, Paavo A.
    University of Helsinki, Finland.
    Cuberes, M. Teressa
    University of Castilla-La Mancha, Spain.
    Willför, Stefan
    Åbo Akademi University, Finland.
    Salmen, Lennart
    RISE, Innventia.
    Mikkonen, Kristi S.
    University of Helsinki, Finland.
    Softwood-based sponge gels2016In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 5, p. 3221-3238Article in journal (Refereed)
    Abstract [en]

    Crosslinking-aided gelation was utilized to prepare hydrogels from softwood polysaccharides, with spruce galactoglucomannans (GGM)—a group of largely unexploited hemicelluloses—as the main component, aiming at conversion into sponge-like aerogels. Cellulose nanofibrils were used for the formation of a reinforcing network, which was further crosslinked together with a GGM matrix by ammonium zirconium carbonate, an inorganic salt that is regarded as safe for use in food packaging. The hydrogels were freeze-dried into stiff, low-density aerogels with 98 % of their volume composed of air-filled pores. When immersed in water, the aerogels absorbed water up to 37 times their initial weight, demonstrating elasticity and repeatable and reversible sponge capacity. The developed concept reassembles the wood polysaccharides in a new way, creating interesting possibilities for utilizing the abundant “green gold,” GGM. The obtained biobased materials could find application potential, for example, in the field of food packaging and could contribute in the reduction of the usage of petroleum-based plastics in the future.

  • 9. Albertsson, A.-C.
    et al.
    Voepel, J.
    Edlund, U.
    Dahlman, Olof
    RISE, Innventia.
    Söderqvist-Lindblad, M.
    Design of renewable hydrogel release systems from fiberboard mill wastewater2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 5, p. 1406-1411Article in journal (Refereed)
    Abstract [en]

    A new route for the design of renewable hydrogels is presented. The soluble waste from masonite production was isolated, fractionized, and upgraded. The resulting hemicellulose rich fraction was alkenyl-functionalized and used in the preparation of covalently cross-linked hydrogels capable of sustained release of incorporated agents. Said hydrogels showed a Fickian diffusion-based release of incorporated bovine serum albumin. Also, a method for the coating of seeds with hydrogel was developed. The sustained release of incorporated growth retardant agents from the hydrogel coating on rape seeds was shown to enable the temporary inhibition of germination.

  • 10.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Dedic, Dina
    RISE, Innventia.
    Karpenja, Tatjana
    RISE, Innventia.
    Magnusson, Mikael
    RISE, Innventia.
    Modorato-Rosta, Caroline
    RISE, Innventia.
    Rosén, Fredrik
    RISE, Innventia.
    Sundin, Konstantin
    RISE, Innventia.
    Lindström, Mikael
    RISE, Innventia.
    Lucisano, Marco
    RISE, Innventia.
    Towards a cellulose-based society: current trends, future scenarios, and the role of the wood biorefinery2016In: Proceedings of the 14th European workshop on lignocellulosics and pulp, 2016, Vol. 2, p. 125-127Conference paper (Other academic)
    Abstract [en]

    There is a great need to maintain research for a future in which the traditional value chains of the forest industry are combined with the needs and demands of a bio-based economy. In such a future, the pulp mill biorefinery will be a crucial node. In order to map the transformation from a fossil-based society to a cellulose-based society, a global consumer survey has been made. In addition, interviews and workshops with various players throughout the bio-economy field have been accomplished. Several current trends that affect the road to a cellulose-based society have been identified. These trends are describing the effects of urbanization, consumer behaviour, new business models, material recycling, open innovation, and the need for early demonstration of new research. The trends have been combined with uncertainties into a number of plausible scenarios describing the society and the role of cellulose in the year 2030.

  • 11.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Larsson, Karolina
    RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE, Innventia.
    Kubat, Mikaela
    RISE, Innventia. RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Karlström, Katarina
    RISE, Innventia.
    Norberg, Lars
    RISE, Innventia.
    Anadolyan, Shant
    RISE, Innventia.
    Peciulyte, Ausra
    Chalmers University of Technology, Sweden.
    Olsson, Lisbeth
    Chalmers University of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia.
    The supramolecular structure of cellulose-rich wood and wheat straw pulps can be a determinative factor for enzymatic hydrolysability2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 39-39, article id 11Conference paper (Other academic)
    Abstract [en]

    Conversion of biomass to biofuels and other products is a research area that is currently attracting a great amount of interest, particularly because such production may be envisaged as a key part of any bio-based economy. Lignocellulosic biomass is abundant and sustainable, and can therefore potentially support large-scale production of biofuel as an alternative to petroleum-based fuel.

    The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.

    In addition, experiments were carried out aiming at identifying suitable conditions for pre-treatment of wheat straw, for the purpose of making cellulose rich pulps with improved enzymatic reactivity. Two sets of conditions for pre-treatment of wheat straw were identified; a combination of low temperature alkaline washing and acid pre-hydrolysis, or high temperature acid pre-hydrolysis. Both bleached wheat straw pulps showed similar enzymatic reactivity. However, the enzymatic reactivity of both bleached wheat straw pulps was found to be significantly less than what has been achieved for wood pulps. A probable explanation for the low enzymatic reactivity of the bleached wheat straw pulp can be the small pore size, limiting the access for enzymes to the cellulose surfaces in the fibre wall interior.Text, figures and tables in an extended abstract (< 4 pages with title and references).

  • 12.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Larsson, Karolina
    RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE, Innventia.
    Kubat, Mikaela
    RISE, Innventia. RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Karlström, Katarina
    RISE, Innventia.
    Peciulyte, Ausra
    Chalmers University of Technology, Sweden.
    Olsson, Lilsbeth
    Chalmers University of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia.
    The supramolecular structure of cellulose-rich wood pulps can be a determinative factor for enzymatic hydrolysability2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 6, p. 3991-4002Article in journal (Refereed)
    Abstract [en]

    The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.

  • 13.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Larsson, Karolina
    RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE, Innventia.
    Kubat, Mikaela
    RISE, Innventia. RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Karlström, Katarina
    RISE, Innventia.
    Peciulyte, Ausra
    Olsson, Lisbeth
    The influence of various pulp properties on the enzymatic hydrolyzability2014Conference paper (Refereed)
  • 14.
    Aldaeus, Fredrik
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Olsson, Anne-Mari
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Miniaturized determination of ash content in kraft lignin samples using oxidative thermogravimetric analysis2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 2, p. 280-282Article in journal (Refereed)
    Abstract [en]

    A study has been made of several aspects of determination of ash content in kraft lignin samples using thermogravimetric analysis (TGA). Three different methods were used; with the main differences between the methods being that two have a temperature hold at 250 deg C to remove volatiles and that the three methods use different maximum temperatures, namely 525, 550 and 575 deg C, respectively. The three kraft lignins used were produced using the LignoBoost lignin isolation process. It has been demonstrated that the results obtained by the different temperature programmes showed no significant difference. The results were comparable with those from using oven ignition. Moreover, the limit of quantification was several orders of magnitude lower than when using oven ignition. It has been recommended that if TGA is used for determination of ash content, a temperature programme from a standard method should be used, which should be mentioned together with the results. The temperature programme in method one (corresponding to ISO 1762) was the shortest and the preferable method. A well as requiring less labour due to fewer movements in the analytical protocol, the TGA methods enabled a high sample throughput due to autosampling possibilities.

  • 15.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Olsson, Anne-Mari
    RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE, Innventia.
    Miniaturized determination of ash content in kraft lignin samples using thermogravimetric analysis2015In: 18th International Symposium on Wood, Fiber and Pulping Chemistry, September 9-11, 2015, Vienna, 2015, p. 352-354Conference paper (Other academic)
    Abstract [en]

    Thermogravimetric analysis (TGA) in oxidative conditions is a promising alternative to ignition in oven for the determination of inorganic residue, commonly referred to as ash. It is here shown that TGA can be used with temperature programs resembling those in standardized methods for oven ignition, and obtainequivalent results even though the sample amount is several orders of magnitude lower. The precision and limit of quantification of TGA is also discussed.

  • 16.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Schweinebarth, Hannah
    RISE, Innventia.
    Jacobs, Anna
    RISE, Innventia.
    Simplified determination of Klason lignin in black liquor and lignin samples2010In: 11th European workshop on lignocellulosics and pulp: EWLP 2010, 2010, p. 45-48Conference paper (Other academic)
  • 17.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Schweinebarth, Hannah
    RISE, Innventia.
    Törngren, Per
    RISE, Innventia.
    Jacobs, Anna
    RISE, Innventia.
    Simplified determination of total lignin content in kraft lignin samples and black liquors2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 4, p. 601-604Article in journal (Refereed)
  • 18. Alexandrescu, L.
    et al.
    Syverud, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Belosi, F.
    Nanofibers against nanoparticles:: Cellulosic nanoparticles for nanoparticle aerosol filtration2012Conference paper (Refereed)
  • 19. Alexandrescu, L.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Iotti, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Belosi, F.
    Gatti, A.M.
    Air filtration of nano-particles using cellulose nanofibrils2012Conference paper (Refereed)
  • 20.
    Alexandrescu, Laura C.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Gatti, Antonietta Maria
    ISTEC-CNR, Italy.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cytotoxicity tests of cellulose nanofibril-based structures2013In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 4, p. 1765-1775Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils based on wood pulp fibres are most promising for biomedical applications. Bacterial cellulose has been suggested for some medical applications and is presently used as wound dressing. However, cost-efficient processes for mass production of bacterial cellulose are lacking. Hence, fibrillation of cellulose wood fibres is most interesting, as the cellulose nanofibrils can efficiently be produced in large quantities. However, the utilization of cellulose nanofibrils from wood requires a thorough verification of its biocompatibility, especially with fibroblast cells which are important in regenerative tissue and particularly in wound healing. The cellulose nanofibril structures used in this study were based on Eucalyptus and Pinus radiata pulp fibres. The nanofibrillated materials were manufactured using a homogenizer without pre-treatment and with 2,2,6,6-tetramethylpiperidine-1-oxy radical as pre-treatment, thus yielding nanofibrils low and high level of anionic charge, respectively. From these materials, two types of nanofibril-based structures were formed; (1) thin and dense structures and (2) open and porous structures. Cytotoxicity tests were applied on the samples, which demonstrated that the nanofibrils do not exert acute toxic phenomena on the tested fibroblast cells (3T3 cells). The cell membrane, cell mitochondrial activity and the DNA proliferation remained unchanged during the tests, which involved direct and indirect contact between the nano-structured materials and the 3T3 cells. Some samples were modified using the crosslinking agent polyethyleneimine (PEI) or the surfactant cetyl trimethylammonium bromide (CTAB). The sample modified with CTAB showed a clear toxic behaviour, having negative effects on cell survival, viability and proliferation. CTAB is an antimicrobial component, and thus this result was as expected. The sample crosslinked with PEI also had a significant reduction in cell viability indicating a reduction in DNA proliferation. We conclude that the neat cellulose nanostructured materials tested in this study are not toxic against fibroblasts cells. This is most important as nano-structured materials based on nanofibrils from wood pulp fibres are promising as substrate for regenerative medicine and wound healing.

  • 21.
    Alftan, Johan
    et al.
    RISE, Innventia.
    Tillander, Olof
    RISE, Innventia.
    Trost, Thomas
    RISE, Innventia.
    Tysen, Aron
    RISE, Innventia.
    Kihlstedt, Annika
    RISE, Innventia. RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Failure due to perforation in corrugated board boxes2013Conference paper (Refereed)
    Abstract [en]

    Corrugated board boxes are often used as secondary packaging to protect consumer goods during transport. In shelf ready packaging, the boxes are perforated so that the front and top of the box can be easily removed and the remainder of the box can be used to store and display the goods. The perforations however also make the box weaker and less efficient for protection. The balance between the require-ments is today found by trial and error, but could benefit from a more systematic approach. In this study, we started with one of the basic tests of corrugated board boxes, the box compression test. A reference box without perforation and three boxes with different perforation were tested. During the box compression test, a pressure sensitive film registered the distribution of load, an IR camera registered heat from dissipa-tive processes such as plasticity and fracture, and a displacement transducer was used to measure out-of-plane deflection of box panels. All boxes, independent of perforation, failed at similar compression forces, suggesting that the box compression test alone is not an adequate test for performance of the perforated boxes. It was however observed that the perforation did influence the failure of the boxes. The proximity to perforation affected where the panels failed. Analysis of displacement indicated that the perforations main-ly were loaded in compression or shear. During transport and handling, more severe loading situations for the perforations would occur which other tests can capture. Vibration tests can be used to study fatigue. Box compression tests with misaligned stacked boxes, loading of the whole box in other modes such as shear, or drop tests will all introduce complex loading were also tension and out-of-plane shear will occur. Climate tests can give effects similar to fatigue. Climate variations also has a large effect on creep.

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  • 22.
    Alfthan, Johan
    RISE, Innventia.
    Experimental study of non-linear stress relaxation and creep of paper materials and the relation between the two types of experiments2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 3, p. 351-357Article in journal (Refereed)
    Abstract [en]

    The non-linear time-dependent mechanical behaviour of three different commercial paper grades was investigated. Stress relaxation and creep tests were carried out in MD and CD using different load levels. The strain in each test was split in a linear part and a non-linear part. From the stress and the linear part of the strain in the test, a stress relaxation modulus or a creep compliance was calculated. The stress relaxation moduli and creep compliances determined in this way were observed to be independent of the load level. The stress relaxation moduli and creep compliances for each paper were further independent of the loading direction (MD/CD) when scaled by the elastic modulus. It was also shown that the stress relaxation modulus was approximately equal to the inverse of the creep compliance, which is what would have been expected if linear viscoelastic theory had been applicable.

  • 23.
    Alfthan, Johan
    et al.
    RISE, Innventia.
    Björklund, Magnus
    Measuring creep with confidence2014Conference paper (Refereed)
  • 24.
    Alm, H.K.
    et al.
    RISE, Innventia.
    Ström, Göran
    RISE, Innventia.
    Karlström, Katarina
    Schoelkopf, J.
    Gane, P.A.C.
    Effect of excess dispersant on surface properties and liquid interactions on calcium carbonate containing coatings2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 1, p. 82-92Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to identify what effects excess amount of sodium polyacrylate, a commonly used dispersant, has on the coating properties and the interaction between ink and the paper coating in offset printing. Since polyacrylate strongly interacts with calcium ions, soluble calcium salt was added to some coating colours to illustrate the impact of charge neutralization by calcium ions. It was found that the coating structure was only slightly affected by the extra addition of polyacrylate, showing some weak flocculation, whereas the surface chemistry was strongly influenced. The coatings became more polar and interacted more strongly with water. This resulted in slower ink setting and reduced ink-paper coating adhesion, especially in the presence of applied water/dampening solution, which are identified as contributory factors in ink piling and print mottle.

  • 25.
    Almgren, K.M.
    et al.
    RISE, Innventia.
    Gamstedt, E.K.
    RISE, Innventia.
    Characterization of interfacial stress transfer ability by dynamic mechanical analysis of cellulose fiber based composite materials2010In: Composite interfaces (Print), ISSN 0927-6440, E-ISSN 1568-5543, Vol. 17, no 9, p. 845-861Article in journal (Refereed)
    Abstract [en]

    The stress transfer ability at the fiber-matrix interface of wood fiber composites is known to affect the mechanical properties of the composite. The evaluation of interface properties at the level of individual fibers is however difficult due to the small dimensions and variability of the fibers. The dynamical mechanical properties of composite and constituents, in this case wood fibers and polylactide matrix, was here used together with micromechanical modeling to quantify the stress transfer efficiency at the fiber-matrix interface. To illustrate the methodology, a parameter quantifying the degree of imperfection at the interface was identified by inverse modeling using a micromechanical viscoelastic general self-consistent model with an imperfect interface together with laminate analogy on the composite level. The effect of moisture was assessed by comparison with experimental data from dynamic mechanical analysis in dry and moist state. For the wood fiber reinforced polylactide, the model shows that moisture absorption led to softening and mechanical dissipation in the hydrophilic wood fibers and biothermoplastic matrix, rather than loss of interfacial stress transfer ability.

  • 26.
    Ambjörnsson, Helene Almlöf
    et al.
    Karlstad University, Sweden.
    Östberg, Linda
    Karlstad University, Sweden.
    Schenzel, Karla C.
    Martin Luther University Halle-Wittenberg, Germany.
    Larsson, Per Tomas
    RISE, Innventia.
    Germgård, Ulf
    Karlstad University, Sweden.
    Enzyme pretreatment of dissolving pulp as a way to improve the following dissolution in NaOH/ZnO2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 4, p. 385-391Article in journal (Refereed)
    Abstract [en]

    The dissolution of a softwood dissolving pulp in a NaOH/ZnO system was improved by means of a three-stage pretreatment with an initial xylanase treatment, followed by an alkaline extraction, and finally an endoglucanase stage. The solubility of the pulp increased from 29% to 81%, although the crystallinity and the specific surface area of the pulp did not change during the enzymatic treatment.

  • 27.
    Andersson, Christian
    et al.
    RISE, Innventia.
    Fellers, Christer
    RISE, Innventia.
    Evaluation of the stress-strain properties in the thickness direction: Particularly for thin and strong papers2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 287-294Article in journal (Refereed)
    Abstract [en]

    The performance of the paper in a number of converting operations such as creasing, bending, printing, and plastic coating put great demands on the mechanical properties in the thickness direction of the material. The knowledge of strength, elastic- and plastic behavior in tension and compression in the thickness direction is needed for a comprehensive description of the performance of the material in these operations. In spite of its importance, very few publications deal with the evaluation of the entire tensile stress-strain curve of paper in the thickness direction. A likely reason for this is the intrinsic difficulty of testing a thin, uneven, porous, fibrous and compressible material such as paper with sufficient precision and testing time efficiency. The z-directional strength test is usually performed by fastening the paper by means of double-adhesive tape to metal platens. The platens are fastened in a testing machine and strained to break. The adhesion of the tape is the limiting factors for how strong papers that can be tested. The tape-based method also is expected to have a lower limit in grammage due to the penetration of the adhesive. The aim of the present publication was to show a procedure how to evaluate the entire stress-elongation curve in the z-direction of papers, using a lamination method for fastening the paper to the metal platens. From this curve the z-strength, z-modulus, z-strain at break, zenergy at break and z-fracture energy could be extracted. Such information is, so far, non-existing in the literature.

  • 28.
    Andersson, Linnea
    et al.
    Stockholm University, Sweden; Oregon State University, USA.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars Göran
    KTH Royal Institute of Technology, Sweden.
    Bergström, Lennart
    Stockholm University, Sweden.
    Evaluating pore space in macroporous ceramics with water-based porosimetry2013In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, no 6, p. 1916-1922Article in journal (Refereed)
    Abstract [en]

    We show that water-based porosimetry (WBP), a facile, simple, and nondestructive porosimetry technique, accurately evaluates both the pore size distribution and throat size distribution of sacrificially templated macroporous alumina. The pore size distribution and throat size distribution derived from the WBP evaluation in uptake (imbibition) and release (drainage) mode, respectively, were corroborated by mercury porosimetry and X-ray micro-computed tomography (μ-CT). In contrast with mercury porosimetry, the WBP also provided information on the presence of "dead-end pores" in the macroporous alumina.

  • 29.
    Anheden, Marie
    et al.
    RISE, Innventia.
    Ehn, Christian
    RISE, Innventia.
    The role of intermediate products in biorefinery development: Kraft lignin and pyrolysis oil as intermediates for production of naphtha cracker feed from forest-based raw materials2015In: NWBC 2015. Proceedings of the 6th Nordic Wood Biorefinery Conference held in Helsinki, Finland, 20-22 Oct. 2015, 2015, p. 210-219Conference paper (Refereed)
    Abstract [en]

    Research has been undertaken to estimate key performance factors important for development of biomass value chains with intermediate products. In the case selected, the end-product had to be suitable as feed product to a naphtha cracker. Pyrolysis oil and kraft lignin were the investigated intermediates, while yield, cost and carbon dioxide footprint were compared with direct production of bio naphtha from forest residues at the petrochemical plant and fossil naphtha. Three bio-based value chains were evaluated: without intermediate; with pyrolysis oil as intermediate; and with kraft lignin separated from black liquor as intermediate. Innventia AB's simulation model in WinGEMS was used to simulate the hypothetical reference pulp mill and the effects of integration with the lignin removal (LignoBoost) and pyrolysis equipment. It has been concluded that the use of intermediates produced integrated with decentralised local industrial plants could reduce total cost and carbon dioxide emissions of transporting forest based biomass to a centrally located conversion plant. However, the economic benefit was not very large compared with the overall value chain cost to produce the final product. Kraft lignin from pulp production was a very interesting intermediate, particularly in the case of the economic benefit

  • 30.
    Ankerfors, Mikael
    et al.
    RISE, Innventia.
    Aulin, Christian
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Nanocellulose research and developments at Innventia2011Conference paper (Refereed)
  • 31.
    Ankerfors, Mikael
    et al.
    RISE, Innventia.
    Duker, Elisabeth
    BillerudKorsnäs AB, Sweden.
    Lindström, Tom
    RISE, Innventia.
    Topo-chemical modification of fibres by grafting of carboxymethyl cellulose in pilot scale2013In: Nordic Pulp and Paper Research Journal, ISSN 0283-2631 , no 1, p. 6-14Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to graft carboxymethyl cellulose (CMC) on to bleached softwood kraft pulp at temperatures below 100°C and to do a pilot paper machine trial in order to examine the influence of the CMC on dewatering, sheet formation and mechanical properties. During the pilot trial, one CMC grafted pulp was compared to a pulp with 3 different refining degrees. It was shown that CMC-grafting improves the mechanical properties of paper with only a minor effect on the sheet density. It was also shown that the CMC grafting is less detrimental to dewatering than refining and at a certain tensile index a higher dry content after pressing could be reached. The formation number of the paper produced in the FEX trial was not significantly affected by the addition of CMC.

  • 32.
    Ankerfors, Mikael
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Energy efficient manufacture of microfibrillated cellulose by attachment of carboxymethyl cellulose2013Conference paper (Refereed)
  • 33.
    Ankerfors, Mikael
    et al.
    BillerudKorsnäs AB, Sweden.
    Lindström, Tom
    RISE, Innventia.
    Glad Nordmark, Gunborg
    RISE, Innventia.
    Multilayer assembly onto pulp fibres using oppositely charged microfibrillated celluloses, starches, and wetstrength resins: Effect on mechanical properties of CTMP-sheets2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 1, p. 135-141Article in journal (Refereed)
    Abstract [en]

    The effects of multilayering of microfibrillar cellulose (MFC) onto a chemi-thermomechanical pulp (CTMP), from which the fines material had been removed, were investigated with regard to the mechanical properties of hand-sheets. In one series of experiments, the CTMP was multilayered with cationic MFC/anionic MFC (C-MFC/A-MFC) at various addition levels and sheets made in a conventional sheet former, pressed, and dried at room temperature. This experimental series was complemented with a second series, where sheets were made in a Rapid Köthen sheet former. In a third series of experiments, the CTMP was multilayered using a cationic polyamideamine epichlorohydrine resin (PAE) and an AMFC. Sheets were formed using the Rapid Köthen sheet former. Finally, in a fourth series of experiments, the MFC multilayering experiments were compared with multilayering experiments using cationic starch/anionic starch (C-starch/A-Starch). MFC-multilayering (C-MFC/A-MFC) gave inferior strength gain at a low addition level compared to starch multilayering, but (compared on a weight basis) the strength seemed to level off using starches at high addition levels, whereas there were a continuous increase in strength using MFC multilayering. Multilayering using PAE/A-MFC was found to give a higher strength gain than both C-MFC/A-MFC and C-starch/A-starch multilayering. Sheet density was slightly affected (<14%) by the multilayering techniques used in these experiments.

  • 34.
    Ankerfors, Mikael
    et al.
    BillerudKorsnäs AB, Sweden.
    Lindström, Tom
    RISE, Innventia.
    Söderberg, L. Daniel
    KTH Royal Institute of Technology, Sweden.
    The use of microfibrillated cellulose in fine paper manufacturing: Results from a pilot scale papermaking trial2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 3, p. 476-483Article in journal (Refereed)
    Abstract [en]

    In this work the strength enhancing capabilities of microfibrillated cellulose (MFC) in highly filled papers was studied. Both the MFC production and the paper making were done in pilot scale under realistic industrial conditions. The results clearly show that MFC (2.5-5.0 wt-%) could improve the mechanical properties of highly filled papers (20-35 wt-% filler contents). All studied dry mechanical properties were improved and the improvements were most pronounced for Z-strength and fracture toughness. By combining the MFC with a C-starch dosage further improvements in mechanical properties could be achieved. The improvements in mechanical properties enabled increased filler content with retained properties. The filler increase could be achieved at the same time as the sheet formation and the dry content after pressing were improved.

  • 35.
    Ankerfors, Mikael
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Söderberg, L. Daniel
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    The use of microfibrillated cellulose in high filler fine papers2013Conference paper (Refereed)
    Abstract [en]

    The field of communication, printing and writing papers has become an increasingly competitive field during the latest years as the market demand of printing and writing papers and newsprint has finally started to decline in the developed economies. One obvious approach to stay competitive is to increase the filler content of such papers. High filler paper is not a new idea and numerous approaches have been tested over the years to produce such papers. In order to reach industrial implementation, pilot-scale research and development under industrial conditions is necessary as a step after laboratory studies. Therefore an environment has been developed in order to perform projects targeting existing technologies for high filler applications as well as the new possibilities incurred by e.g. microfibrillated cellulose.

  • 36.
    Ansari, Farhan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lindh, Erik L.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Furo, Istvan
    KTH Royal Institute of Technology, Sweden.
    Johansson, Mats K. G.
    KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Interface tailoring through covalent hydroxyl-epoxy bonds improves hygromechanical stability in nanocellulose materials2016In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 134, p. 175-183Article in journal (Refereed)
    Abstract [en]

    Wide-spread use of cellulose nanofibril (CNF) biocomposites and nanomaterials is limited by CNF moisture sensitivity due to surface hydration. We report on a versatile and scalable interface tailoring route for CNF to address this, based on technically important epoxide chemistry. Bulk impregnation of epoxide-amine containing liquids is used to show that CNF hydroxyls can react with epoxides at high rates and high degree of conversion to form covalent bonds. Reactions take place inside nanostructured CNF networks under benign conditions, and are verified by solid state NMR. Epoxide modified CNF nanopaper shows significantly improved mechanical properties under moist and wet conditions. High resolution microscopy is used in fractography studies to relate the property differences to structural change. The cellulose-epoxide interface tailoring concept is versatile in that the functionality of molecules with epoxide end-groups can be varied over a wide range. Furthermore, epoxide reactions with nanocellulose can be readily implemented for processing of moisture-stable, tailored interface biocomposites in the form of coatings, adhesives and molded composites.

  • 37.
    Ansari, Farhan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sjöstedt, Anna
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Hierarchical wood cellulose fiber/epoxy biocomposites: Materials design of fiber porosity and nanostructure2015In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 74, p. 60-68Article in journal (Refereed)
    Abstract [en]

    Delignified chemical wood pulp fibers can be designed to have a controlled structure of cellulose fibril aggregates to serve as porous templates in biocomposites with unique properties. The potential of these fibers as reinforcement for an epoxy matrix (EP) was investigated in this work. Networks of porous wood fibers were impregnated with monomeric epoxy and cured. Microscopy images from ultramicrotomed cross sections and tensile fractured surfaces were used to study the distribution of matrix inside and around the fibers - at two different length scales. Mechanical characterization at different relative humidity showed much improved mechanical properties of biocomposites based on epoxy-impregnated fibers and they were rather insensitive to surrounding humidity. Furthermore, the mechanical properties of cellulose-fiber biocomposites were compared with those of cellulose-nanofibril (CNF) composites; strong similarities were found between the two materials. The reasons for this, some limitations and the role of specific surface area of the fiber are discussed.

  • 38. Antonsson, S.
    et al.
    Mäkelä, Petri
    RISE, Innventia.
    Fellers, Christer
    RISE, Innventia.
    Lindström, M. E.
    Comparison of the physical properties of hardwood and softwood pulps2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 4, p. 409-414Article in journal (Refereed)
    Abstract [en]

    High mechano-sorptive creep resistance, i.e., good creep resistance in environments with changing relative humidity, is one of the key requirements for linerboards. The aim of this study was to investigate the influence of pulp types and pulp properties on the mechano-sorptive creep of kraftliner. A high-yield softwood, kraftliner pulp, and four different hardwood pulps were investigated. The physical properties of laboratory sheets were evaluated, with emphasis on the mechanosorptive creep properties. The results showed that the density increase due to increased beating significantly improved the tensile stiffness of all pulps, while its effect on the isocyclic creep stiffness was less pronounced. The hardwood pulps showed higher tensile stiffness, better mechano-sorptive creep properties, and lower hygroexpansion than the softwood pulp at a given density. However, the softwood pulp did exhibit better tensile strength and fracture toughness properties than the hardwood pulps. The results imply that hardwood pulps can be competitive with softwood pulps in kraftliners, provided that their tensile strength and fracture toughness properties can be improved by, for example, chemical means. Furthermore, the isocyclic creep stiffness correlates with the ratio of tensile stiffness to hygroexpansion, indicating that this ratio can be used for engineering estimates of the mechano-sorptive creep performance of paper materials.

  • 39. Antonsson, S.
    et al.
    Pulkkinen, I.
    Fiskari, J.
    Karlström, Katarina
    RISE, Innventia.
    Lindström, M.E
    The relationship between hygroexpansion, tensile stiffness, and mechano-sorptive creep in bleached hardwood kraft pulps2010In: Appita journal, ISSN 1038-6807, Vol. 63, no 3, p. 231-234Article in journal (Refereed)
    Abstract [en]

    Hygroexpansion coefficient and tensile stiffness are important parameters in many paper applications. This study compares several bleached industrial hardwood kraft pulps, comprising five eucalypt pulps from South America, Europe, and Africa as well as an acacia pulp from Asia and a birch pulp from Scandinavia. Refined and unrefined pulps are compared. The results indicate significant differences in hygroexpansion but smaller differences in tensile stiffness index at comparable densities. No single factor offering a reasonable explanation of these differences in hygroexpansion coefficient, such as carbohydrate composition, fibre dimensions, or fibre form, was found. However, correlation between hygroexpansion coefficient and the mechano-sorptive creep stiffness was observed. We suggest that the hygroexpansion coefficient at a given tensile stiffness level can be used to rank pulps in terms of their mechano-sorptive creep properties.

  • 40. Aslan, M.
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Sørensen, B.F.
    Madsen, B.
    Strength Variability of Single Flax Fibres2011In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 46Article in journal (Refereed)
  • 41.
    Athley, Karin
    et al.
    RISE, Innventia.
    Granlöf, Lars
    RISE, Innventia.
    Söderberg, Daniel
    RISE, Innventia.
    Ström, Göran
    RISE, Innventia.
    Optimizing the benefit of retention chemicals2014Conference paper (Refereed)
    Abstract [en]

    Pre-flocculation of filler has been tested as a concept for improving the retention of filler and the strength properties of the sheet. The impact of the size of the filler floes on the mechanical retentionin a fibre network was investigated using a modified laboratory hand sheet former. The mechanical retention was found to increase linearly with both particle size and grammage of the fibre web. These results were confirmed in a full scale production trial on the FEX pilot paper machine at Innventia. Here different filler floe sizes were created through different chemical pre-flocculation strategies. The particle size in the flow to the headbox was measured with FBRM, and a linear relation between particle size and filler retention was found. Corresponding linear relation was seen in a pilot trial when adding filler and retention aid conventionally. This implies that mechanical retention constitute an important part of the filler retention not only upon pre-flocculation but also with conventional addition of filler and retention aid. Thus, the particle size before the headbox can be a good indicator of the retention level. For the conventional application of a two component retention aid system, the increased filler retention correlated to impaired formation and decreased sheet strength. On the contrary, pre-flocculation led to an increase in both sheet strength and filler retention, demonstrating the advantage of pre-flocculating filler.

  • 42.
    Athley, Karin
    et al.
    RISE, Innventia.
    Granlöf, Lars
    RISE, Innventia.
    Söderberg, L. Daniel
    RISE, Innventia.
    Ankerfors, Mikael
    RISE, Innventia.
    Ström, Göran R.
    RISE, Innventia.
    Mechanical retention - Influence of filler floc size and grammage of the fibre web2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 202-207Article in journal (Refereed)
    Abstract [en]

    An investigation of the impact of particle size on the mechanical retention of particles in a fibre network has been conducted. The particles used were five sets of quartz particle fractions having fairly narrow particle size distributions with average particle size ranging from a few μm to around 100 μm. The particles were used to model flocculated filler aggregates as part of a larger study of the effect of pre-flocculation on mechanical retention. Pre-flocculation of the filler is a possible strategy to increase the filler content of paper without deterioration of strength properties. A modified laboratory hand sheet former, known as the Rapid Drainage Device (RDD) was used. The major modification consisted of a long pipe that acted as a suction leg, which provides a dewatering vacuum at the same level as on a paper machine. The experimental results showed that mechanical filler retention increased linearly with particle size and grammage of the fibre layer above a critical grammage which depended on particle size. The linear relation was also seen in a pilot scale trial on the FEX pilot-paper machine at Innventia. During this trial fine paper was produced using pre-flocculated filler where the mean particle size of the flocs and fibres was measured in the flow to the headbox. The results from this pilot trial show that mechanical retention is an important part of the total filler retention. Drainage time and therefore drainage resistance increased with the grammage of the fibre layer and amount of quartz particle added. Drainage time, compared at total grammage (i.e. the sum of fibre and quartz particle grammage) was lowest for a fraction of medium-sized particles, with a median size of 35 μm. There was no obvious effect on retention or drainage resistance of a change in the dewatering pressure from 27.5 to 41.5 kPa.

  • 43. Aulin, C.
    et al.
    Johansson, E.
    Wågberg, L.
    Lindström, Tom
    RISE, Innventia.
    Self-organized films from cellulose i nanofibrils using the layer-by-layer technique2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 4, p. 872-882Article in journal (Refereed)
    Abstract [en]

    The possibility of forming self-organized films using only charge-stabilized dispersions of cellulose I nanofibrils with opposite charges is presented, that is, the multilayers were composed solely of anionically and cationically modified microfibrillated cellulose (MFC) with a low degree of substitution. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using a quartz crystal microbalance with dissipation (QCM-D) and stagnation point adsorption reflectometry (SPAR). The adsorption behavior of cationic/anionic MFC was compared with that of polyethyleneimine (PEI)/anionic MFC. The water contents of five bilayers of cationic/anionic MFC and PEI/anionic MFC were approximately 70 and 50%, respectively. The MFC surface coverage was studied by atomic force microscopy (AFM) measurements, which clearly showed a more dense fibrillar structure in the five bilayer PEI/anionic MFC than in the five bilayer cationic/anionic MFC. The forces between the cellulose-based multilayers were examined using the AFM colloidal probe technique. The forces on approach were characterized by a combination of electrostatic and steric repulsion. The wet adhesive forces were very long-range and were characterized by multiple adhesive events. Surfaces covered by PEI/anionic MFC multilayers required more energy to be separated than surfaces covered by cationic/anionic MFC multilayers.

  • 44. Aulin, C.
    et al.
    Netrval, J.
    Wågberg, L.
    Lindström, Tom
    RISE, Innventia.
    Aerogels from nanofibrillated cellulose with tunable oleophobicity2010In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 6, no 14, p. 3298-3305Article in journal (Refereed)
    Abstract [en]

    The formation of structured porous aerogels of nanofibrillated cellulose (NFC) by freeze-drying has been demonstrated. The aerogels have a high porosity, as shown by FE-SEM and nitrogen adsorption/desorption measurements, and a very low density (&lt;0.03 g cm-3). The density and surface texture of the aerogels can be tuned by selecting the concentration of the NFC dispersions before freeze-drying. Chemical vapor deposition (CVD) of 1H,1H,2H,2H- perfluorodecyltrichlorosilane (PFOTS) was used to uniformly coat the aerogel to tune their wetting properties towards non-polar liquids. An XPS analysis of the chemical composition of the PFOTS-modified aerogels demonstrated the reproducibility of the PFOTS-coating and the high atomic fluorine concentration (ca. 51%) in the surfaces. The modified aerogels formed a robust composite interface with high apparent contact angles (* ≫ 90°) for castor oil (γlv = 35.8 mN m-1) and hexadecane (γlv = 27.5 mN m-1).

  • 45. Aulin, Christian
    et al.
    Gällstedt, Mikael
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Oxygen and oil barrier properties of microfibrillated cellulose films and coatings2010In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 17, no 3, p. 559-574Article in journal (Refereed)
    Abstract [en]

    The preparation of carboxymethylated microfibrillated cellulose (MFC) films by dispersion-casting from aqueous dispersions and by surface coating on base papers is described. The oxygen permeability of MFC films were studied at different relative humidity (RH). At low RH (0%), the MFC films showed very low oxygen permeability as compared with films prepared from plasticized starch, whey protein and arabinoxylan and values in the same range as that of conventional synthetic films, e.g., ethylene vinyl alcohol. At higher RH’s, the oxygen permeability increased exponentially, presumably due to the plasticizing and swelling of the carboxymethylated nanofibers by water molecules. The effect of moisture on the barrier and mechanical properties of the films was further studied using water vapor sorption isotherms and by humidity scans in dynamic mechanical analysis. The influences of the degree of nanofibrillation/dispersion on the microstructure and optical properties of the films were evaluated by field-emission scanning electron microscopy (FE-SEM) and light transmittance measurements, respectively. FE-SEM micrographs showed that the MFC films consisted of randomly assembled nanofibers with a thickness of 5-10 nm, although some larger aggregates were also formed. The use of MFC as surface coating on various base papers considerably reduced the air permeability. Environmental scanning electron microscopy (E-SEM) micrographs indicated that the MFC layer reduced sheet porosity, i.e., the dense structure formed by the nanofibers resulted in superior oil barrier properties.

  • 46.
    Aulin, Christian
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Karabulut, Erdem
    KTH Royal Institute of Technology, Sweden.
    Tran, Amy
    KTH Royal Institute of Technology, Sweden.
    Waisgberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Lindström, Tom
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Transparent nanocellulosic multilayer thin films on polylactic acid with tunable gas barrier properties2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, no 15, p. 7352-7359Article in journal (Refereed)
    Abstract [en]

    The layer-by-layer (LbL) deposition method was used for the build-up of alternating layers of nanofibrillated cellulose (NFC) or carboxymethyl cellulose (CMC) with a branched, cationic polyelectrolyte, polyethyleneimine (PEI) on flexible poly (lactic acid) (PLA) substrates. With this procedure, optically transparent nanocellulosic films with tunable gas barrier properties were formed. 50 layer pairs of PEI/NFC and PEI/CMC deposited on PLA have oxygen permeabilities of 0.34 and 0.71 cm3·μm/m 2·day·kPa at 23 C and 50% relative humidity, respectively, which is in the same range as polyvinyl alcohol and ethylene vinyl alcohol. The oxygen permeability of these multilayer nanocomposites outperforms those of pure NFC films prepared by solvent-casting. The nanocellulosic LbL assemblies on PLA substrates was in detailed characterized using a quartz crystal microbalance with dissipation (QCM-D). Atomic force microscopy (AFM) reveals large structural differences between the PEI/NFC and the PEI/CMC assemblies, with the PEI/NFC assembly showing a highly entangled network of nanofibrils, whereas the PEI/CMC surfaces lacked structural features. Scanning electron microscopy images showed a nearly perfect uniformity of the nanocellulosic coatings on PLA, and light transmittance results revealed remarkable transparency of the LbL-coated PLA films. The present work demonstrates the first ever LbL films based on high aspect ratio, water-dispersible nanofibrillated cellulose, and water-soluble carboxymethyl cellulose polymers that can be used as multifunctional films and coatings with tailorable properties, such as gas barriers and transparency. Owing to its flexibility, transparency and high-performance gas barrier properties, these thin film assemblies are promising candidates for several large-scale applications, including flexible electronics and renewable packaging.

  • 47.
    Aulin, Christian
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Biopolymer Coatings for Paper and Paperboard2011In: Biopolymers: New Materials for Sustainable Films and Coatings / [ed] Plackett David, John Wiley & Sons, 2011, p. 255-276Chapter in book (Other academic)
  • 48.
    Aulin, Christian
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Ström, Göran
    RISE, Innventia.
    Nanocellulose films and coatings with tunable oxygen and water vapor permeability for use in renewable packaging solutions2013Conference paper (Refereed)
  • 49.
    Aulin, Christian
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Salazar-Alvarez, German
    KTH Royal Institute of Technology, Sweden; Stockholm University, Sweden.
    Lindström, Tom
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    High strength flexible and transparent nanofibrillated cellulose-nanoclay biohybrid films with tunable oxygen and water vapor permeability2012In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 4, no 20, p. 6622-6628Article in journal (Refereed)
    Abstract [en]

    A novel, technically and economically benign procedure to combine vermiculite nanoplatelets with nanocellulose fibre dispersions into functional biohybrid films is presented. Nanocellulose fibres of 20 nm diameters and several micrometers in length are mixed with high aspect ratio exfoliated vermiculite nanoplatelets through high-pressure homogenization. The resulting hybrid films obtained after solvent evaporation are stiff (tensile modulus of 17.3 GPa), strong (strength up to 257 MPa), and transparent. Scanning electron microscopy (SEM) shows that the hybrid films consist of stratified nacre-like layers with a homogenous distribution of nanoplatelets within the nanocellulose matrix. The oxygen barrier properties of the biohybrid films outperform commercial packaging materials and pure nanocellulose films showing an oxygen permeability of 0.07 cm3 μm m-2 d-1 kPa -1 at 50% relative humidity. The oxygen permeability of the hybrid films can be tuned by adjusting the composition of the films. Furthermore, the water vapor barrier properties of the biohybrid films were also significantly improved by the addition of nanoclay. The unique combination of excellent oxygen barrier behavior and optical transparency suggests the potential of these biohybrid materials as an alternative in flexible packaging of oxygen sensitive devices such as thin-film transistors or organic light-emitting diode displays, gas storage applications and as barrier coatings/laminations in large volume packaging applications.

  • 50.
    Aulin, Christian
    et al.
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Ström, Göran R.
    RISE, Innventia.
    Multilayered alkyd resin/nanocellulose coatings for use in renewable packaging solutions with a high level of moisture resistance2013In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, no 7, p. 2582-2589Article in journal (Refereed)
    Abstract [en]

    A surprisingly simple and rapid methodology for large-area, lightweight, and thin laminate coatings with remarkable moisture barrier properties is introduced. Commercially available paperboards are coated with thin layers of nanocellulose. The nanocellulose coating induces a surface smoothening effect on the coated sheets as characterized by environmental scanning electron microscopy and white light interferometry. A moisture-protective layer of renewable alkyd resins is deposited on the nanocellulose precoated sheets using a water-borne dispersion coating process or lithographic printing. Through an auto-oxidation process, the applied alkyd resins are transformed into moisture sealant layers. The moisture barrier properties are characterized in detail by water vapor permeability measurements at different levels of relative humidity. The water vapor barrier properties of the nanocellulose precoated substrates were significantly improved by thin layers of renewable alkyd resins. The effect of the alkyd resin properties, coating technologies, and base paper substrates on the final barrier performance of the sheets were studied. It was found that the nanocellulose coating had a notable effect on the homogeneity and barrier performance of the alkyd resin layers and in particular those alkyd resin layers that were applied by printing. The concept is environmentally friendly, energy-efficient, and economic and is ready for scaling-up via continuous roll-to-roll processes. Large-scale renewable coatings applicable for sustainable packaging solutions are foreseen.

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