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  • 1.
    Abbadessa, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Univ Santiago de Compostela, IDIS Res Inst, Ctr Res Mol Med & Chron Dis CIMUS, Campus Vida,Ave Barcelona S-N, Santiago De Compostela 15706, Spain.;Univ Santiago de Compostela, Sch Pharm, Dept Pharmacol Pharm & Pharmaceut Technol, Campus Vida,Ave Barcelona S-N, Santiago De Compostela 15706, Spain..
    Dogaris, Ioannis
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Farahani, Saina Kishani
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. RISE Res Inst Sweden, Dept Mat & Surface Design, Drottning Kristinas Vag 61, SE-11428 Stockholm, Sweden..
    Rautkoski, Hille
    VTT Tech Res Ctr Finland Ltd, POB 1000, FI-02044 Espoo, Finland..
    Holopainen-Mantila, Ulla
    VTT Tech Res Ctr Finland Ltd, POB 1000, FI-02044 Espoo, Finland..
    Oinonen, Petri
    Ecohelix AB, Teknikringen 38, S-10044 Stockholm, Sweden..
    Henriksson, Gunnar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Layer-by-layer assembly of sustainable lignin-based coatings for food packaging applications2023In: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 182, article id 107676Article in journal (Refereed)
    Abstract [en]

    Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging.

  • 2.
    Abbaszad Rafi, Abdolrahim
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Alimohammadzadeh, Rana
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Avella, Angelica
    Mõistlik, Tanel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Jűrisoo, Martin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Kaaver, Andreas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    Tai, Cheuk -Wai
    Lo Re, Giada
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
    A facile route for concurrent fabrication and surface selective functionalization of cellulose nanofibers by lactic acid mediated catalysis2023In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, no 1, article id 14730Article in journal (Refereed)
    Abstract [en]

    Celulose nanofibers are lightweight, recycable, biodegradable, and renewable. Hence, there is a great interest of using them instead of fossil-based components in new materials and biocomposites. In this study, we disclose an environmentally benign (green) one-step reaction approach to fabricate lactic acid ester functionalized cellulose nanofibrils from wood-derived pulp fibers in high yields. This was accomplished by converting wood-derived pulp fibers to nanofibrillated “cellulose lactate” under mild conditions using lactic acid as both the reaction media and catalyst. Thus, in parallel to the cellulose nanofibril production, concurrent lactic acid-catalyzed esterification of lactic acid to the cellulose nanofibers surface occured. The direct lactic acid esterification, which is a surface selective functionalization and reversible (de-attaching the ester groups by cleavage of the ester bonds), of the cellulose nanofibrils was confirmed by low numbers of degree of substitution, and FT-IR analyses. Thus, autocatalytic esterification and cellulose hydrolysis occurred without the need of metal based or a harsh mineral acid catalysts, which has disadvantages such as acid corrosiveness and high recovery cost of acid. Moreover, adding a mineral acid as a co-catalyst significantly decreased the yield of the nanocellulose. The lactic acid media is successfully recycled in multiple reaction cycles producing the corresponding nanocellulose fibers in high yields. The disclosed green cellulose nanofibril production route is industrial relevant and gives direct access to nanocellulose for use in variety of applications such as sustainable filaments, composites, packaging and strengthening of recycled fibers. 

  • 3.
    Abdelaziz, Omar
    et al.
    RISE Research Institutes of Sweden. Lund University, Sweden.
    Capanema, Ewellyn
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ajao, Olumoye
    Canmet ENERGY, Canada.
    Kristensen, Tove
    Lund University, Sweden.
    Hosseinaei, Omid
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Benali, Marzouk
    Canmet ENERGY, Canada.
    Hulteberg, Christian
    Lund University, Sweden.
    A Rapid and Tunable Approach for the Fractionation of Technical Kraft Lignin2023In: Chemical Engineering Transactions, ISSN 1974-9791, E-ISSN 2283-9216, Vol. 99, p. 67-72Article in journal (Refereed)
    Abstract [en]

    Reducing the heterogeneity of technical lignin is essential to obtain predictable and high-performance polymeric materials that are suitable for high-value applications. Organic solvents with different polarities and solubilities can be used to fractionate lignin and reduce the complexity and diversity of its chemical structure. Among the various solvents and solvent mixtures, acetone-water mixtures offer an energy-efficient, cost-effective, and environmentally friendly means of lignin fractionation. In the present study, temperature-induced acetone-water fractionation was investigated to refine the properties of a technical softwood Kraft lignin, i.e., LignoBoost™ lignin. Relatively mild operating conditions were tested, namely, temperatures of 70-110°C and autogenous pressure. A factorial experimental design was developed using the Design-Expert® software, and three factors (temperature, time, and acetone concentration) were investigated. It was found that temperature-induced fractionation could increase lignin homogeneity and maintain high lignin solubilization with a short processing time (<1 h). It was also possible to tune the properties of the soluble lignin fraction (yield and weight-average molecular weight) based on the factorial models developed. The techno-economic evaluation confirmed the commercial viability of this fractionation process. 

  • 4.
    Achtel, Christian
    et al.
    Friedrich Schiller University of Jena, Germany.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. Friedrich Schiller University of Jena, Germany.
    Kosan, Birgit
    TITK Thuringian Institute of Textile and Plastics Research, Germany.
    Seoud, Omar. A.El
    University of São Paulo, Brazil.
    Heinze, Thomas
    Friedrich Schiller University of Jena, Germany.
    Dissolution capacity of novel cellulose solvents based on triethyloctylammonium chloride2017In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 218, no 21, article id 1700208Article in journal (Refereed)
    Abstract [en]

    Dissolution of cellulose from various sources (microcrystalline cellulose and different dissolving grade pulp fibers) is investigated in solvent systems based on triethyl(n-octyl)ammonium chloride (N2228Cl). Clear cellulose solutions are obtained with N2228Cl in a variety of solvents, e.g., dimethyl sulfoxide, N,N-dimethylacetamide, and acetone. It is possible to prepare clear cellulose solutions from pulp fibers with concentrations up to 15 wt%. However, it is found that the cellulose is degraded, especially when neat (i.e., molten) N2228Cl is used as a solvent. The present work includes comprehensive rheological characterization of the cellulose solutions, both with shear and extensional rheology. In most cases, the viscosity values are low (complex viscosities below 100 Pa s for 5–10 wt% dissolved cellulose), and the solutions show more Newtonian than viscoelastic behavior. 

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  • 5.
    Adamopoulos, Stergios
    Technological Educational Institute of Larissa, Greece.
    Fiber analysis techniques for sustainable manufacturing of corrugated board and packaging2006In: Proceedings of the 2006 Naxos International Conference on Sustainable Management and Development of Mountainous and Island Areas: 29th September - 1st October 2006, Island of Naxos, Greece / [ed] Evangelos I. Manolas, Democritus University of Thrace , 2006, Vol. 1, p. 1-9Conference paper (Refereed)
    Abstract [en]

    Environmental – economic pressure and associated regulations have led to a significant increase of recycled paper as the main fibrous component of corrugated board the last years. Corrugating packaging industry is facing the challenge to enhance products derived from recycled pulp and to ensure a satisfactory strength of packages. Advanced techniques are highly needed for the evaluation of packaging fiber supply sources as well as for the utilization of the available resources in an optimal manner. As industrial packaging is based on the characteristics of its constituent fibers, information on the fiber composition of the recycled raw materials is of primary importance for a continual control of fiber sources. This paper reports on the usefulness of fiber analysis techniques as diagnostic methods for assessing the potential quality distribution of fibers for sustainable packaging manufacturing.

  • 6.
    Adamopoulos, Stergios
    AIDIMA, Spain.
    Identification of Fibre Components in Packaging Grade Papers2006In: IAWA Journal, ISSN 0928-1541, Vol. 27, no 2, p. 153-172Article in journal (Refereed)
    Abstract [en]

    Environmental and economic issues have led to a significant increase of recycled paper as the main fibrous component of corrugated board the last years. Qualitative data on the different fibre types are needed for the evaluation of packaging fibre supply sources, which are becoming numerous and heterogeneous. Fifteen different packaging grade papers (7 linerboards and 8 corrugating medium) were selected to represent all the variety of papers available on the Spanish market. The origin of virgin and recycled fibres was identified by their morphological characteristics employing light microscopy and standard fibre analysis techniques. The waste-based papers (Waste based-liners and Fluting), Kraft-liners and Test-liner were highly variable containing 9–18 different wood and nonwood components. Semi-chemical, with 5–13 components, was the less variable grade. Hardwoods were identified as the most important fibre component from a quantitative standpoint. All papers contained in their hardwood mix Betula, Eucalyptus and Populus in significant amounts. Fagus sylvatica and Tilia were also frequently observed and in some papers were amongst major hardwood components. Prominent softwood components were found to be Pinus sylvestris, P. pinaster, P. radiata, Picea, Larix and in some papers Pinus nigra. The lower presence of a variety of softwood, hardwood and nonwood (mainly grasses) species and genera was due to the paper recycling process.

  • 7.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Morphology, properties and recyclability of modified fibres and papers with different chemicals at laboratory, pilot plant and industrial trials2015Conference paper (Other (popular science, discussion, etc.))
  • 8. Adamopoulos, Stergios
    Quality control of packaging fiber sources2006Conference paper (Other academic)
  • 9. Adamopoulos, Stergios
    Quantification of softwood, hardwood and nonwood fibres in packaging grade papers2006In: TAPPI Journal, ISSN 0734-1415, Vol. 5, no 3, p. 27-32Article in journal (Refereed)
    Abstract [en]

    This study determined percentages by weight of the fiber components in 15 papers commonly used to produce corrugating packaging in Spain. The papers are manufactured mainly from recycled raw materials. The percentages were determined by means of standard quantitative fiber analysis techniques and use of appropriate weight factors. Hardwoods were the major fiber component in all papers, except kraft liners, varying from 51% to 92% per weight. Kraft liners had greater softwood content (49%-69%)than hardwood, and the most plentiful softwood classes were pines. Douglas-fir was a contaminating fiber component (weight percentage less than 2%) in almost in every paper. Nonwood fibers, entering the papers through the recycling process, were a significant fiber component (2%-9%) in most of the papers, especially the waste-based papers (liners and flutings). Quantitative fiber composition reflects the differences in quality between the papers. Its usefulness could be further explored in the quality control of paper manufacturing for packaging.

    Application: Packaging grade papers incorporate a variety of wood and nonwood fiber types. Manufacturing of papers of consistent and acceptable quality requires knowledge concerning the quantity of each fiber used.

  • 10.
    Adamopoulos, Stergios
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Birmpilis, D
    Technological Educational Institute of Thessaly.
    Use and properties of recovered paper raw materials for the production of corrugated board2015In: Proceedings of the 14th International Conference on Environmental Science and Technology Rhodes, Greece, 3-5 September 2015, Global NEST , 2015Conference paper (Refereed)
    Abstract [en]

    The difficulty of predicting the properties of paper products produced from heterogeneous sources puts several limitations, which therefore lead to severe economic losses and only a comprehensive characterization will enable their better utilization. The project “RF-CORRUG –Quality control of raw materials from recovered fibres for the production of corrugated board”under the NationalStrategic Reference Framework 2007–2013 ARCHIMEDES IIIdeals with this common technical problem of the corrugated board industry. Specifically, the mainobjective of the project is to supportthe competitiveness of the corrugated board companies (mainly SMEs)by creatinga software tool based on practical models that can predict packaging grade paper properties from fibre data (qualitative, quantitative, morphological) used in their production. This paper presents information on the physical and mechanical properties of recovered packaging papers used in corrugated packaging. A number of different category papers (liners, flutings) used for corrugated board production in Greece were examined. The required paper properties included grammage, porosity, bursting strength, SCT, tensile strength and tearing resistance, and were measured by internationally recognized testersand standards. The data will be used to develop predictive models based on advanced statistical methods for the properties and performance of packagingaccording to information of their recovered raw paper materials.

  • 11.
    Adamopoulos, Stergios
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Karageorgos, Anthony
    Technological Educational Institute of Thessaly, Greece.
    Rapti, Elli
    Center for Research and Technology – Hellas (CERTH), Greece .
    Birbilis, Dimitris
    Technological Educational Institute of Thessaly, Greece.
    Predicting the Properties of Corrugated Base Papers Using Multiple Linear Regression and  Artificial Neural Networks2016In: Drewno, ISSN 1644-3985, Vol. 59, no 198, p. 61-72Article in journal (Refereed)
    Abstract [en]

    The difficulty in predicting the properties and behaviour of paper products produced using heterogeneous raw materials with high percentages of recovered fibres poses restrictions on their efficient and effective use as corrugated packaging materials. This work presents predictive models for the mechanical properties of corrugated base papers (liner and fluting-medium) from fibre and physical property data using multiple linear regression and artificial neural networks. The most significant results were obtained for the prediction of the tensile strength of liners in the cross direction from the origin (wood type, pulp method) of the fibres using linear regression, and the prediction of the compressive strength of fluting-medium in the longitudinal (machine) direction, according to the short-span test, using a neural network with one hidden layer with 6 neurons, with coefficients of determination at 95.14% and 99.28%, respectively

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  • 12.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Larissa, Greece.
    Mai, C
    From wood fibre modification to paper technology: properties of fibres modified with DMDHEU and glutaraldehyde2011In: 3rd biennial International Fibre Engineering Conference, 24 – 26 May, Barcelona, Spain, 2011Conference paper (Other academic)
  • 13.
    Adamopoulos, Stergios
    et al.
    AIDIMA, Spain.
    Martinez, E
    AIDIMA, Spain.
    Ramirez, D.
    AIDIMA, Spain.
    Characterization of packaging grade papers from recycled raw materials through the study of fibre morphology and composition2007In: Global NEST. International Journal, ISSN 1108-4006, Vol. 9, no 1, p. 20-28Article in journal (Refereed)
    Abstract [en]

    The restrictions in availability of forest-based raw materials along with favourable environmental policies towards alternative sources of raw materials have forced corrugated packaging industry to shift towards recycled paper and other fibre sources such as non-wood and agro-residues. The variability in raw pulp materials with increasing percentages of recycled fibres is a very common technical problem for the corrugated packaging industry worldwide. Corrugating packaging production is facing the challenge to ensure a satisfactory strength of packages despite the increase of recycled paper as the main fibrous component. Sustainable manufacturing of papers of consistent and acceptable quality requests comprehensive characterization of the fibrous components, which are becoming more heterogeneous. Understanding the influence that heterogeneous recycled raw materials have on packaging grade paper properties offers great potential value to the corrugated board and packaging industry.

    57 linerboards and corrugating medium were selected to represent all the variety of paper grades available on the market at the moment for the production of corrugated board in Spain. The papers were analyzed for their fibre morphology (fibre length, fibre width, lumen diameter, cell wall width and flexibility) and fibre composition (softwood to hardwood and nonwood fibre count and weight) and their strength (compression, bursting and crushing resistance) was evaluated. All the determinations were in accordance with the relevant TAPPI Test Methods. The significant differences found in most of the anatomical characteristics, fibre composition and strength properties among the paper grades reflected the diverse raw materials used for their production as well as their qualitative differences. By means of simple correlation the influence of fibre characteristics and composition on the strength of the papers was determined under two different conditions, at 23 o C and 50% RH and at 20 o C and 90% RH.

    The results demonstrate that besides the physical-mechanical characterization of packaging grade papers, fibre anatomy and composition can be used successfully as a complementary practical test to predict the performance of papers. The application of the predicting correlations is proposed for the evaluation of the fibre supplies for the packaging industry. An enormous potential for cost reduction can be created by the selection of the most appropriate and inexpensive combination of grade papers for a specific packaging use

  • 14. Adamopoulos, Stergios
    et al.
    Mertinez, E
    Ramirez, D
    Characterization of packaging grade papers from recycled raw materials through the study of fibre morphology and composition2005In: Proceedings of the 9th International Conference on Environmental Science and Technology: Rhodes, Rhodes Island, Greece, 1 - 3 September 2005 ; Volume of Abstracts / [ed] University of the Aegean, 2005, Vol. A, p. 18-25Conference paper (Refereed)
  • 15.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Karditsa, Greece.
    Oliver, José-Vicente
    AIDIMA, Spain.
    Fiber composition of packaging grade papers as determined by the Graff “C” staining test2006In: Wood and Fiber Science, ISSN 0735-6161, Vol. 38, no 4, p. 567-575Article in journal (Refereed)
    Abstract [en]

    A qualitative and quantitative analysis of the fiber components of 15 representative papers that are used for the production of corrugated board was carried out by the Graff "C" staining test. The method of processing of softwood, hardwood, and nonwood fibers was determined under a light microscope by their color reactions with the stain. All papers, due to the use of recycled pulp raw materials in their manufacturing, were found to incorporate in their furnish fibers that had been produced with a variety of pulping processes: chemical, mechanical, and semi-mechanical. The recycled-based papers (recycled-liner and recycled-medium) were proved to be the most variable comprising 12-15 different fiber components, while in some of the semi-chemicals only up to 7 components were identified. The weight percentages of the fiber components calculated by the application of weight factors showed that in almost all papers the most important fiber component from a quantitative standpoint was hardwood unbleached kraft followed by softwood unbleached kraft. Besides hardwood unbleached semi-chemical pulp and mechanical softwood pulp that were also plentiful in the papers, there was a smaller number of other components which sum, however, accounted for a significant fraction in the total furnish weight. The results taken on the total softwood, hardwood, and nonwood fibers content of the papers demonstrate that Graff "C" staining test is adequate to analyze both the structure and quality of packaging grade papers in practical industrial testing.

  • 16.
    Adamopoulos, Stergios
    et al.
    Democritus University of Thrace, Greece.
    Oliver, José-Vicente
    AIDIMA, Spain.
    Qualitative and quantitative fibre analysis in recycled raw materials for packaging2006In: Forest Products Journal, ISSN 0015-7473, Vol. 56, no 2, p. 58-60Article in journal (Refereed)
    Abstract [en]

    Understanding the influence that heterogeneous recycled raw materials have on packaging-grade paper performance offers great potential value to the corrugated board and packaging industry. Fifty-seven linerboards and corrugating medium were selected to represent all the variety of paper grades available on the Spanish market at the moment for the production of corrugated board. The origin of softwood, hardwood, and nonwood fibers and their percentages by weight were determined with light microscopy and standard fiber analysis techniques.

  • 17. Adamopoulos, Stergios
    et al.
    Passialis, Costas
    Voulgaridis, Elias
    Fibre characteristics of papers used in European corrugated packaging industry2009In: ATIP. Association Technique de L'Industrie Papetiere, ISSN 0997-7554, Vol. 63, no 4, p. 14-21Article in journal (Refereed)
  • 18. Adamopoulos, Stergios
    et al.
    Passialis, Costas
    Voulgaridis, Elias
    Fibre characteristics of papers used in European corrugated packaging industry2008Conference paper (Refereed)
  • 19. Adamopoulos, Stergios
    et al.
    Passialis, Costas
    Voulgaridis, Elias
    Oliver, JV
    Utilization of recycled fibre materials in the European corrugated packaging industrial sector2008In: 2nd International Conference on Engineering for Waste Valorisation WasteEng08, June 3-5, Patras, Greece, 2008Conference paper (Refereed)
  • 20. Adamopoulos, Stergios
    et al.
    Voulgaridis, E
    Passialis, C
    Morphology and identification of fibre furnish components of papers used in the production of corrugated board2013In: Celuloza Si Harti, ISSN 1220-9848Article in journal (Refereed)
  • 21.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Thessaly, Greece.
    Voulgaridis, Elias
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    CARACTERISTICILE MATERIALULUI FIBROS ŞI PROPRIETĂŢILEHÂRTIEI RECICLATE FOLOSITE ÎN FABRICAREA CARTONULUIONDULAT: Morphology and identification of fibre furnish components of papers used in the production of corrugated board2013In: 7th International Symposium on Advanced Technologies for the Pulp, Paper and Corrugated Board Industry, 2013Conference paper (Refereed)
    Abstract [en]

    The manufacture of corrugated board containers (boxes, trays, etc.) involves a productionchain integrated by paper manufacturers, semi-elaborates (corrugated board) manufacturers andcontainer manufacturers, the majority of which in Europe are SMEs. Nowadays, corrugated boardcontainers are mostly manufactured with recovered paper. The greatest threat faced by thementioned production chain is related to the lack of quality and availability of recovered paper asraw material. Specifically, one of the most important properties of packaging paper is itsmechanical strength, which depends mostly on the length of the fibres of which paper iscomposed. These fibres are longer in virgin pulps (those coming from papers obtained fromwood, i.e. not yet recycled). However, the high pressure on the demand - as well as the currenteconomic and ecological restrictions in the use of forest based materials - has led to a situation inwhich very little quantity of virgin fibre enters the recycling chain. This means that the strengthquality of recycled fibres - and by extension of the papers - is constantly decreasing with the ongoingrecycling cycles. In addition, recovered paper presents a very high variability, whatconstitutes an obstacle when it comes to manufacturing containers having homogeneousproperties fixed by the customers at fixed costs. The difficulty of predicting the properties ofpaper products produced from heterogeneous sources puts several limitations, which thereforelead to severe economic losses and only a comprehensive characterization will enable their betterutilization. The project “RF-CORRUG – Quality control of raw materials from recovered fibresfor the production of corrugated board” under the National Strategic Reference Framework 2007–2013 ARCHIMEDES III deals with this common technical problem of the corrugated boardindustry. Specifically, the main objective of the project is to support the competitiveness of thecorrugated board companies (mainly SMEs) by creating a software tool based on practical modelsthat can predict packaging grade paper properties from fibre data (qualitative, quantitative, morphological) used in their production. This papers presents information on fibres (qualitativeand quantitative analysis, morphology) and packaging papers (physical and mechanicalproperties) used in corrugated packaging. A number of different category papers (liners, flutings) used for corrugated board production in Greece were examined. The main fibre characterizingtechniques, employed were fibre furnish analysis, morphological analysis of fibre, lightmicroscopy, scanning electron microscopy (SEM). In addition, zero span tensile test was done tomeasure the average fibre strength of fibre. The required paper properties were measured byinternationally recognized testers and standards. The data will be used to develop predictivemodels based on advanced statistical methods for the properties and performance of packagingpapers according to information of their fibres.

  • 22.
    Adamopoulos, Stergios
    et al.
    Greece.
    Voulgaridis, Elias
    Greece.
    Passialis, Costas
    Greece.
    Recycled Waste Paper and the Corrugated Packaging Industry in Europe2009In: Proceedings of 24th International Conference on Solid Waste Technology and Management: Philadelphia, PA USA, March 15-18, 2009, 2009, p. 400-411Conference paper (Refereed)
  • 23.
    Afshar, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering.
    Size effect on mechanical properties of wood in transverse direction2022Conference paper (Refereed)
  • 24.
    Afshar, Reza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Uppsala University.
    Cheylan, Matthieu
    École Nationale Supérieure de Mécanique et des Microtechniques, Besançon.
    Almkvist, Gunnar
    Department of Molecular Sciences, Swedish University of Agricultural Sciences.
    Ahlgren, Anders
    The Swedish National Maritime and Transport Museums, The Vasa Museum.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Mechanics. Uppsala University.
    Creep in oak material from the Vasa ship:: verification of linear viscoelasticity and identification of stress thresholds2020In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 78, no 6, p. 1095-1103Article in journal (Refereed)
    Abstract [en]

    Creep deformation is a general problem for large wooden structures, and in particular for shipwrecks in museums. In this study, experimental creep data on the wooden cubic samples from the Vasa ship have been analysed to confrm the linearity of the viscoelastic response in the directions where creep was detectable (T and R directions). Isochronous stress–strain curves were derived for relevant uniaxial compressive stresses within reasonable time spans. These curves and the associated creep compliance values justify that it is reasonable to assume a linear viscoelastic behaviour within the tested ranges, given the high degree of general variability. Furthermore, the creep curves were ftted with a one-dimensional standard linear solid model, and although the rheological parameters show a fair amount of scatter, they are candidates as input parameters in a numerical model to predict creep deformations. The isochronous stress–strain relationships were used to defne a creep threshold stress below which only negligible creep is expected. These thresholds ranges were 0.3–0.5 MPa in the R direction and 0.05–0.2 MPa in the T direction.

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  • 25.
    Agnhage, Tove
    et al.
    University of Borås, Swedish School of Textiles.
    Nierstrasz, Vincent
    University of Borås, Swedish School of Textiles.
    Perwuelz, A.
    Guan, J.P.
    Chen, G.Q.
    Eco-design innovative methods for fabric finishing2014Conference paper (Other academic)
  • 26. 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)
  • 27. 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.

  • 28.
    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.

  • 29.
    Ahlroth, Mikael
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Bialik, Marta
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Jensen, Anna
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy.
    Hydrothermal carbonisation of effluent sludge2017In: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017: NWBC 2017, Stockholm: RISE Bioekonomi , 2017, p. 156-158Conference paper (Refereed)
    Abstract [en]

    Research was carried out to investigate hydrothermal carbonisation (HTC) treatment of different effluent sludges from the pulp and paper industry in a Parr-reactor. Sludge samples were evaluated from a thermomechanical paper (TMP) mill and a kraft market pulp mill (NSWBK). The issues studied included HTC treatment time; addition of acid and alkali; dewatering properties of the resulting slurry; and non-process element (NPE) concentration in the original sludge, the filtrate and the filter cake. It was found that HTC improved the fuel quality. Alkali metals were depleted in TMP and NSWBK sludge and in both cases, the sludge was easier to dewater. The yield was better for TMP than NSWBK sludge and the yield losses had a negative impact on the NSWBK sludge. TMP sludge was already a viable boiler fuel and the treatment improved the fuel qualities even more. The HTC treatment of the NSWBK sludge resulted in lower chlorine and potassium, with lower fuel-nitrogen resulting in lower nitrous oxide. Although HTC treatment improved the low heating value of the sludge, this was counteracted by yield loss. Compared with untreated NSWBK, the overall energy impact was negative. HTC treatment offered mixed opportunities from the viewpoint of the recovery cycle.

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  • 30.
    Ahmed, Sheikh Ali
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Linnaeus University, Linnaeus Knowledge Environments, Advanced Materials.
    Adamopoulos, Stergios
    Swedish university of agricultural sciences, Sweden.
    Li, Junqiu
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Kovacikova, Janka
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Prediction of mechanical performance of acetylated MDF at different humid conditions2020In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 23, p. 1-16, article id 8712Article in journal (Refereed)
    Abstract [en]

    Change of relative humidity (RH) in surrounding environment can greatly affect the physical and mechanical properties of wood-based panels. Commercially produced acetylated medium density fiberboard (MDF), Medite Tricoya®, was used in this study to predict strength and stiffness under varying humid conditions by separating samples in parallel (//) and perpendicular (⊥) to the sanding directions. Thickness swelling, static moduli of elasticity (MOEstat) and rupture (MORstat), and internal bond (IB) strength were measured at three different humid conditions, i.e., dry (35% RH), standard (65% RH) and wet (85% RH). Internal bond (IB) strength was also measured after accelerated aging test. A resonance method was used to determine dynamic modulus of elasticity (MOEdyn) at the aforementioned humid conditions. Linear regression and finite element (FE) analyses were used to predict the MDF’s static bending behavior. Results showed that dimensional stability, MOEstat, MORstat and IB strength decreased significantly with an increase in RH. No reduction of IB strength was observed after 426 h of accelerated aging test. A multiple regression model was established using MOEdyn and RH values to predict MOEstat and MORstat. In both directions (// and ⊥), highly significant relationships were observed. The predicted and the measured values of MOEstat and MORstat were satisfactorily related to each other, which indicated that the developed model can be effectively used for evaluating the strength and stiffness of Medite Tricoya® MDF samples at any humid condition. Percent errors of two different simulation techniques (standard and extended FE method) showed highly efficient way of simulating the MDF structures with low fidelity.

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  • 31.
    Ahmed, Sheikh Ali
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology. Linnaeus University, Linnaeus Knowledge Environments, Advanced Materials.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Poggi, Francesco
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Walther, Thomas
    IKEA Industry AB, Sweden.
    Resonance and time-of-flight methods for evaluating the modulus of elasticity of particleboards at different humid conditions2020In: Wood research, ISSN 1336-4561, Vol. 65, no 3, p. 365-380Article in journal (Refereed)
    Abstract [en]

    Non-destructive testing of wood panels by either resonance or time-of-flight (TOF) methods provides possibilities for predicting their static bending properties. In the present study, three non-destructive devices (BING - Beam Identification by Non-destructive Grading by CIRAD, Montpellier, France, Fakopp Ultrasonic Timer and Sylvatest TRIO) were used for measuring the dynamic stiffness of different particleboard types. Fakopp Ultrasonic Timer and Sylvatest TRIO produce ultrasonic pulses to measure the sound velocity while BING uses resonance frequencies. Commercially produced particleboards with different thickness and densities were used to measure the dynamic modulus of elasticity (MOEdyn) in two directions (parallel and perpendicular to the production line) and at three different humidity levels (dry - 35%, standard - 65% and wet - 85% RH in constant temperature of 20°C ). MOEdyn of particleboards were correlated with the static moduli of elasticity (MOEstat) and rupture (MORstat). It was found that the non-destructive methods gave higher MOEdyn values in both production directions than that of MOEstat values. MOEdyn was found to decrease from dry to wet conditions. A very strong and statistically significant correlation existed between MOEdyn and static bending properties. MOEdyn correlated stronger to MOEstat than MORstat. At different humidity level, all three methods- Fakopp Ultrasonic Timer, BING and Sylvatest TRIO analyses showed good predicting capabilities to estimate MOEstat and MORstat of different particleboard types with high level of accuracy.

  • 32.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Hagman, Olle
    Luleå University of Technology.
    Cloutier, Alain
    Laval University, Canada.
    Fang, Chang-Hua
    Laval University, Canada.
    Elustondo, Diego
    Luleå University of Technology.
    Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression2013In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 24, p. 8571-8579Article in journal (Refereed)
    Abstract [en]

    Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 °C with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.

  • 33.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Development of a new rapid method for mould testing in a climate chamber: preliminary tests2013In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 71, no 4, p. 451-461Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to develop fast, simple and robust solid wood mould testing methods for the use in small-scale laboratory tests. The objective was to investigate mould susceptibility of different wood materials within the batches. The proposed method is based on natural contamination of non-sterile surfaces in climates conducive to mould growth. For this purpose, a climate chamber with regulated temperature and relative humidity was used. The conditioning chamber was divided into upper and lower chamber by a thin layer of stainless steel placed horizontally above the fan to minimise air circulation to the sample in the upper compartment. Mould-infected samples from outdoor tests were used as a source of mould inocula, and test trials were conducted on Scots pine (Pinus sylvestris L.) sapwood. Samples were suspended from the top of the upper chamber, and the chamber was exposed to different temperature and humidity levels. Severe mould infestation was observed after 12–14 days of incubation. Visual mould rating was then performed. Regardless of some constraints, this test method was very simple, fast, and effective. More importantly, unlike other test methods, it closely models mould infestation as it would occur under natural condition.

  • 34.
    Ahmed, Sheikh Ali
    et al.
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Morén, Tom
    Luleå University of Technology.
    Mould susceptibility of Scots pine (Pinus sylvestris L.) sapwood: Impact of drying, thermal modification, and copper-based preservative2013In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 85, p. 284-288Article in journal (Refereed)
    Abstract [en]

    The development of mould on wood surfaces depends on several factors. Although mould does not affect the mechanical properties of wood, it greatly reduces the aesthetic value of wood such as the sapwood of Scots pine (Pinus sylvestris L.), which is very prone to mould. In addition, adverse health effects of mould on humans are a great concern. Different types of dried and treated wood were used to observe whether they had enhanced durability against mould following an accelerated laboratory test method in a climate chamber. Samples were green, air-dried, industrially thermally modified, treated with copper-based preservative, and kiln-dried wood, which were tested within a single test run. The test produced the following main results: The thermal modification increased the durability of the wood, and the protective effectiveness of alternative treatments was comparable to that of commercially available copper-based treatment. However, the initial moisture content of the samples during mould exposure had a great influence on the onset of mould growth. The risk of mould susceptibility of industrial kiln-dried lumber can be reduced by drying using the double-layering technique and planing off the nutrient enriched evaporation surfaces.

  • 35. Ait Benhamou, Anass
    et al.
    Boukind, Soumia
    Khalili, Houssine
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Moubarik, Amine
    El Achaby, Mounir
    Kassab, Zineb
    Sehaqui, Houssine
    Strong and Flame-Resistant Nanocellulose Sheets Derived from Agrowastes via a Papermaking-Assisted Process2024In: acs applied polymer materials, ISSN 2637-6105, Vol. 6, no 5, p. 2763-2776Article in journal (Refereed)
    Abstract [en]

    In recent decades, the production of nanocellulose has gained significant attention. Nanocellulose-based film materials have found widespread applications in various high-end sectors owing to their remarkable characteristics. Nevertheless, the limitation of certain functional properties, such as resistance to water and fire, has posed challenges to their broader utilization. In this study, we conducted a comparative investigation on the impact of two distinct chemical modifications, namely, TEMPO-mediated oxidation and phosphorylation, on the production of nanocellulose sheets via a papermaking-assisted process. This approach explores the synergistic effects of these modifications in enhancing the properties of cellulose nanofibers for nanopaper production. To achieve this, we proposed utilizing Henna stems as an alternative source of cellulosic material, aiming to harness untapped agricultural residues as a sustainable alternative to conventional sources such as wood and cotton. The phosphorylated Henna nanopaper exhibited substantial enhancements in terms of mechanical properties, wettability, fire resistance, and water vapor permeability when compared to the TEMPO-modified Henna nanopaper. In conclusion, our findings underscore the potential of Henna stems as an environmentally sustainable source of cellulose for nanofiber production, positioning it as a promising alternative to wood and other lignocellulosic sources for advanced applications.

  • 36.
    Alberth, Lena
    KTH, School of Chemical Science and Engineering (CHE).
    Experimentell studie av kinetiken vid peroxidblekning av pappersmassa2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During TCF-bleaching of pulp, hydrogen peroxide is one of the main chemicals. Today it is difficult to control the bleaching stages. The process operators must consider the production rate, changes in the bleach ability of the pulp and delays of trends in the control system. The PO-bleaching stage at Södra Cell Värö has approximately a retention time of four(4) hours and it is first after that, a result of a change in the process can be seen. Overbleaching is expensive due to high chemical need and therefore it is requested to find a way to control and optimize the peroxide bleaching stage. One way to do this was too simulate the stage experimentally and from those kinetic data accomplish a mathematical model that predicts the brightness increase of the pulp.

    Pulp from the mill was bleached at the laboratory under controlled conditions and with charges similar to what are used in the plant. The parameters that were studied at lab were temperature, hydrogen peroxide charge and alkali charge as they affect the brightness mostly. A model for brightness increase was adjusted to the achieved bleaching data. Equations for consumption of hydrogen peroxide and hydroxide anions were also developed from analyses of the bleaching filtrates. 

    From the start parameters, as concentration of the chemicals, temperature and pulp concentration, the model predicts the brightness well according to verification of data from mill and verification bleaching at laboratory. The value from the model is somewhat higher compared to that of the plant but that was expected due to the fact that the conditions at lab give a cleaner system. For those parameters that were studied, the model did adjust well to changes made and according to the verification at lab it was seen that the model also worked for changes in pulp concentration and different brightness at the beginning of the stage.

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  • 37. 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.

  • 38.
    Aldaeus, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    The Bioeconomy Research Programme 2018-20202018In: The 8th Nordic Wood Biorefinery Conference: NWBC 2018: proceedings / [ed] Hytönen Eemeli, Vepsäläinen Jessica, Espoo: VTT Technical Research Centre of Finland , 2018, p. 83-Conference paper (Other academic)
  • 39.
    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.

  • 40.
    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).

  • 41.
    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.

  • 42.
    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)
  • 43.
    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.

  • 44.
    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.

  • 45.
    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)
  • 46.
    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.

  • 47.
    Alfthan, Johan
    et al.
    RISE, Innventia.
    Björklund, Magnus
    Measuring creep with confidence2014Conference paper (Refereed)
  • 48.
    Ali, Silvia
    et al.
    STFI-Packforsk, Stockholm, Sweden .
    Salmén, Lennart
    From wood shavings to mechanical pulp - a new raw material?2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, ISSN 0283-2631, Vol. 20, no 4, p. 418-422Article in journal (Refereed)
    Abstract [en]

    Wood chips used in the thermomechanical pulping (TMP) process were originally designed to suit the chemical pulping process. The production of small wood pieces more suitable for the TMP process could lead to an energy saving in this energy-intensive process. This paper discusses the potential benefits of using wood shavings instead of chips as the raw material for TMP production. In some exploratory trials, wood shavings with a thickness of about 2 mm and wood chips were refined in two steps under normal TMP process conditions in a pilot refiner. The first-stage refining was performed under pressurized conditions at 130°C. The second-stage refining was performed at atmospheric pressure at approximately 100°C at four different energy levels. The quality of the pulp produced from wood shavings was found to be better than that of the pulp produced from wood chips, with respect to both strength properties (except tear index) and optical properties at comparable energy levels. The potential for energy savings at a given tensile index using wood shavings instead of the traditional chips is estimated to be about 25%.

  • 49.
    Alieva, Fidan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Prediction of Plastic Fragments in Recycled Paper Using Near-Infrared Spectroscopy2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sustainability has gained a lot of attention in the field of research. Researchers and consumers both prioritize sustainability and environmental issues over previously dominant materials, such as plastic. Packaging and disposable items that used to be made of plastic have largely been replaced with paper. Unfortunately, paper does not perform as well as plastic regarding barrier properties against grease, oxygen, or water vapor. Barrier properties are an important factor when choosing packaging material for food, among other things, as they help maintain the shelf life of the product. In order to improve the properties of the paper packaging and expand its use, the paper is coated with a polymer. However, the polymer contributes to challenges in the recycling of the products as some of the polymer attaches to the fibers, causing difficulties in the separation of each material. Small fragments of plastic may end up in the material streams and the recycled pulp due to the existing challenges in completely removing plastic from cellulosic substrates during recycling.

    This thesis analyzes the possibilities of identifying and classifying plastic fragments of polyethylene (PE) and polyvinyl alcohol (PVOH) in recycled paper sheets using near-infrared spectroscopy together with multivariate data analysis. The purpose of the work is to develop models that can identify possible residues that may appear in recycled products from various industries.

    Paper sheets of two different grammages and six different compositions of recycled fiber and virgin fiber were created and scanned by NIR, with and without plastic film under the sheets. The scans were used to develop classification models to identify and categorize scans not included in the calibration data set. The performance of the models was tested by applying them to images of sheets of paper with plastic fragments of different sizes and different type underneath.

    The results indicated potential in the method. The prediction of the paper sheets with a lower grammage was mostly correct, whereas the classification of polyethylene showed the best performance. There was some noise in the prediction of the plastic fragments, regardless of the grammage of the paper. The noise may be due to a wide variation in the calibration data set since it consisted of paper sheets of six different compositions. A large part of the noise was incorrectly classified as polyvinyl alcohol, which can be due to differences in the manufacturing process of the plastic films. The conclusion of the thesis is that it is feasible to identify and categorize plastic fragments of polyethylene and polyvinyl alcohol in recycled paper sheets with a certain margin of error. It can be stated that the method shows promise, but further research and development in the field is required to build models that can be applied to a wider range of samples.

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  • 50.
    Alimadadi, Majid
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Foam-formed Fiber Networks: Manufacturing, Characterization, and Numerical Modeling: With a Note on the Orientation Behavior of Rod-like Particles in Newtonian Fluids2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fiber networks are ubiquitous and are seen in both industrial materials (paper and nonwovens) and biological materials (plant cells and animal tissues). Nature intricately manipulates these network structures by varying their density, aggregation, and fiber orientation to create a variety of functionalities.

    In conventional papermaking, fibrous materials are dispersed in water to form a sheet of a highly oriented two-dimensional (2D) network. In such a structure, the in-plane mechanical and transport properties are very different from those in the out-of-plane direction. A three-dimensional (3D) network, however, may offer unique properties not seen in conventional paper products.

    Foam, i.e., a dispersed system of gas and liquid, is widely used as the suspending medium in different industries. Recently, foam forming was studied extensively to develop the understanding of foam-fiber interactions in order to find potential applications of this technology in papermaking.

    In this thesis, a method for producing low-density, 3D fiber networks by utilizing foam forming is investigated and the structures and mechanical properties of such networks are studied. Micro-computed tomography is used to capture the 3D structure of the network and subsequently to reproduce artificial networks. The finite element method is utilized to model the compression behavior of both the reproduced physical network and the artificial networks in order to understand how the geometry and constitutive elements of the foam-formed network affect its bulk mechanical properties. Additionally, a method was studied in order to quantify the orientation behavior of particles in a laminar Newtonian flow based on the key parameters of the flow which control the orientation.

    The resulting foam-formed structures were extremely bulky. Yet despite this high bulk, the fiber networks retained good structural integrity. The compression behavior in the thickness direction was characterized by extreme compressibility and high strain recovery after compression. The results from the modeling showed that the finite-deformation mechanical response of the fiber network in compression was satisfactorily captured by the simulation. However, the artificial network shows higher stiffness than the simulated physical network and the experiment. This discrepancy in stiffness was attributed to macroscopic structural non-uniformities in the physical network, which result in increased local compliance. It was also found that the friction between the fibers, as well as the fiber curvature, had a negligible impact on the compression response of the fiber network, while defects (in the form of kinks) had an effect on the response in the last stages of compression. The study of the orientation behavior of particles at different flow velocities, particle sizes, and channel geometries suggests that it might be possible to utilize the flow shear rate as a means to quantify the orientation behavior.

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