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  • 1.
    Almlöf, Heléne
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Schenzel, Karla
    Department of Natural Science III, Institute of Agriculture and Nutritional Science, Martin Luther University, Germany.
    Germgård, Ulf
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Carboxymethyl cellulose produced at different mercerization conditions and characterized by NIR FT Raman spectroscopy and chemometric methods2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 2, p. 1918-1932Article in journal (Refereed)
  • 2.
    Boudreau, Jonna
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Influence of Various Pulp Properties on the Adhesion Between Tissue Paper and Yankee Cylinder Surface2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 2, p. 2107-2114Article, review/survey (Refereed)
    Abstract [en]

    The strength of the adhesion between the paper and the drying Yankee cylinder is of great importance with respect to the final properties of a tissue paper product. Therefore, the effects of a few potentially important pulp properties have been evaluated in laboratory experiments. Four highly different kraft pulps were used, and the adhesion strength was measured by means of the force required when scraping off a paper from a metal surface with a specifically designed knife mounted on a moving cart. The adhesion strength was observed to increase with increasing grammage and increasing degree of beating of the pulp. It was also found that pulpscontainingmore fines, or with higher hemicellulose content, gave rise to higher adhesion strength.

  • 3.
    Deshpande, Raghu
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Sundvall, Lars
    MoRe Research, Örnsköldsvik, Sweden.
    Grundberg, Hans
    Domsjö Fabriker, Örnsköldsvik, Sweden.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    The influence of different types of bisulfite cooking liquors on pine wood components2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 3, p. 5961-5973Article in journal (Refereed)
    Abstract [en]

    Single stage sodium bisulfite cooking of pine was carried out to study the initial phase of the bisulfite cook and the experiments were carried out using either a lab or a mill prepared cooking acid. The chemical consumption, the pH profile and the pulp yield with respect to cellulose, lignin, glucomannan, xylan and extractives were investigated. The pulp composition with respect to carbohydrates and lignin content was summarized in a kinetic model. The initial phase of the bisulfite cook was extended to 5 h cooking time down to a final pulp yield of about 60 %. The side reactions with respect to thiosulfate and sulfate formation were investigated continuously in all experiments. The cooking temperature used in these experiments was 154 °C.

  • 4.
    Ekbåge, Daniel
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Nilsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Håkansson, Helena
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Time series analysis of refining conditions and estimated pulp properties in a chemi-thermomechanical pulp process2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 3, p. 5451-5466Article in journal (Refereed)
    Abstract [en]

    Frequently sampled process data from a conical disc refiner and infrequently sampled pulp data from a full scale chemi-thermomechanical pulp (CTMP) mill were evaluated to study autocovariance with aspects of potential dynamic modelling applicability. Two trial measurements with an online pulp analyzer at decreased sampling intervals were performed. For variability analysis, time-series containing up to one day of operational data were used. At the chip refiner, the clearest significant autocovariance was identified for the specific electricity consumption, based on the longer sequences. Most of the estimated pulp properties indicated low or non-significant autocovariance, limiting applicability of a specific dynamic model. A mill trial was conducted to investigate the impact from an increase in the conical disc gap on the specific electricity consumption and the resulting freeness. The response time from the gap change in the refiner to measured change in freeness was estimated at 19 min, which was approximately the hydraulic residence time in the latency chest. The relevance of this study lies in applicability of mill-data-driven modelling to capture the dynamics of a specific refining process. Through mill trials the sampling speed of pulp properties was more than doubled to gain insights into short term systematic variations by applying time-series-analysis.

  • 5.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Henriksson, Gunnar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Pelletizing pure biomass substances to investigate the mechanical properties and bonding mechanisms2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 1, p. 1202-1222Article in journal (Refereed)
    Abstract [en]

    Solid fuel for heating is an important product, and for sustainability reasons, it is important to replace nonrenewable fuels with renewable resources. This entails that the raw material base for pellet production has to increase. A broader spectrum of materials for pelleting involves variation in biomass substances. This variation, due to lack of knowledge, limits the possibilities to increase the pellet production using new raw materials. In this study, pellets were produced with a single pellet press from 16 different pure biomass substances representing cellulose, hemicellulose, other polysaccharides, protein, lignin, and extractives, and five different wood species, representing softwoods and hardwoods. All pellets were analyzed for the work required for compression and friction, maximum force needed to overcome the backpressure, pellet hardness, solid density, and moisture uptake. The results showed that the hardest pellets were produced from the group of celluloses, followed by rice xylan and larch arbinogalactan. The weakest pellets were from the group of mannans. Conclusions are that the flexible polysaccharides have a greater impact on the pelletizing process than previously known, and that the differences between xylan and glucomannan may explain the difference in the behavior of pelletizing softwoods and hardwoods.

  • 6.
    Germgård, Ulf
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Asif Javed, Muhammad
    The Reactivity of Prehydrolyzed Softwood Kraft Pulps after Prolonged Cooking Followed by Chlorite Delignification2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 3, p. 2581-2591Article in journal (Refereed)
  • 7.
    Heijnesson-Hulten, Anette
    et al.
    AkzoNobel, SE-44580 Bohus, Sweden..
    Guo, Sanchuan
    Karlstad University.
    Basta, Jiri
    AkzoNobel, SE-44580 Bohus, Sweden.
    Daniel, Geoffrey
    Swedish Univ Agr Sci, Dept Forest Prod Wood Sci, SE-75007 Uppsala, Sweden.
    Zhan, Huaiyu
    S China Univ Technol, State Key Lab P&P Engn, Guangzhou 510640, Guangdong, Peoples R China.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Impact of Drying on the Quality of Bamboo Kraft Pulps2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 1, p. 1245-1257Article in journal (Refereed)
    Abstract [en]

    This study investigates how drying affects the quality of bamboo kraft pulps. Two bamboo pulps, cooked to different kappa numbers (i.e. 10 and 26) and D(EOP)D bleached to approximately the same brightness, were used to examine the relationship between cooking, drying, refining, and pulp/fiber properties. Drying of the two pulps caused, as expected, a loss in tensile and burst strength while the tear index was improved. The bleached high kappa pulp required less energy to reach a certain Schopper Riegler value and exhibited greater strength properties than the low kappa number pulp. These differences were also maintained after drying. Results showed that the properties of the pulp before drying determined the final strength potential of the pulp after drying. Thus, kraft cooking of bamboo to high kappa number prior to bleaching gave pulps with improved response to refining and pulp strength properties, which in turn influenced the properties of the dried pulps.

  • 8.
    Henriksson, Lisa
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Andersson, Simon
    Emerging Cooking Solutions Sweden AB.
    Ohlson, Mattias
    Emerging Cooking Solutions Sweden AB.
    Bioresources for Sustainable Pellet Production in Zambia: Twelve Biomasses Pelletized at Different Moisture Content2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 2, p. 2550-2575Article in journal (Refereed)
    Abstract [en]

    The use of charcoal and firewood for cooking is common in Zambia,and its utilization is suchthat the deforestation rate is high, energy utilization is low, and unfavorable cooking methods lead to high death rates due to indoor air pollution mainly from particulate matter and carbon monoxide.Byusing an alternative cooking method, such as pellet stoves, it is possible to offer a sustainable solution, provided that sustainable pelletproduction can be achieved. In this study, 12different available biomaterials were pelletizedina single pellet unitto investigate their availability as raw materials for pellet production in Zambia. The study showedthat sicklebush and pigeon pea generatedthe same pelleting properties correlated withcompression and frictionand that both materials showedlow moisture uptake. The study also identifiedtwo groups of materials that broadenedthe raw material base and helpedto achieve sustainable pellet production.Group 1consisted of materials with equal pelletingabilities (miombo, peanut shell, pigeon pea,and sicklebush) andGroup 2 consistedof materialsthat showed low impact of varying moisture content(eucalyptus, miombo, peanut shell, pigeon pea, and sicklebush). The hardest pellet was made from Tephrosia, which wasfollowed by Gliricidia.

  • 9.
    Hubbe, Martin A.
    et al.
    North Carolina State Univ, Dept Forest Biomat,.
    Alen, Raimo
    University Jyvaskyla, Finland.
    Paleologou, Michael
    FPInnovations, Canada.
    Kannangara, Miyuru
    Natl Res Council Canada.
    Kihlman, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Lignin Recovery from Spent Alkaline Pulping Liquors Using Acidification, Membrane Separation, and Related Processing Steps: A Review2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 1, p. 2300-2351Article in journal (Refereed)
    Abstract [en]

    The separation of lignin from the black liquor generated during alkaline pulping is reviewed in this article with an emphasis on chemistry. Based on published accounts, the precipitation of lignin from spent pulping liquor by addition of acids can be understood based on dissociation equilibria of weak acid groups, which affects the solubility behavior of lignin-related chemical species. Solubility issues also govern lignin separation technologies based on ultrafiltration membranes; reduction in membrane permeability is often affected by conditions leading to decreased solubility of lignin decomposition products and the presence of colloidal matter. Advances in understanding of such phenomena have potential to enable higher-value uses of black liquor components, including biorefinery options, alternative ways to recover the chemicals used to cook pulp, and debottlenecking of kraft recovery processes.

  • 10.
    Johansson, Caisa
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Bras, Julien
    France.
    Mondragon, Inaki
    Spain.
    Nechita, Petronela
    Romania.
    Plackett, David
    Danmark.
    Simon, Peter
    Slovakia.
    Gregor Svetec, Diana
    Slovenia.
    Virtanen, Sanna
    Finland.
    Giacinti Baschetti, Marco
    Italy.
    Breen, Chris
    UK.
    Clegg, Fransic
    UK.
    Aucejo, Susana
    Spain.
    Renewable fibers and bio-based materials for packaging applications-a reveiw of recent developments2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 2, p. 2506-2552Article, review/survey (Refereed)
  • 11.
    Kudahettige-Nilsson, Rasika Lasanthi
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ullsten, Henrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Henriksson, Gunnar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Plastic Composites Made from Glycerol, Citric Acid, and Forest Components2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 3, p. 6600-6612Article in journal (Refereed)
    Abstract [en]

    An ecofriendly approach for the synthesis of plastic biomaterials based on renewable materials suitable for 3D printing application or other applications has been developed. The material was prepared from native (microcrystalline) or amorphous cellulose, citric acid, and glycerol or ethylene glycol, by a pretreatment at 40 degrees C and a curing at 175 degrees C for 1 h. The results showed that tensile properties and the water absorption level of the material were acceptable. The highest strain at break (14%) was obtained from materials made of 10% amorphous cellulose with 90% glycerol/citric acid. It had a maximum stress at 37 MPa. Moreover, materials were without ash content. Possible applications of the material in 3D-printers were discussed. In addition, application of mechanical pulp and wood powder into novel plastic material production was discussed. Foaming during curing might be a problem for this type of material, but this can be avoided by using amorphous cellulose in the recipe.

  • 12.
    Kvarnlöf, Niklas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Oxygen Delignification of Acid Sulfite and Bisulfite Softwood Pulps2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 3, p. 3934-3947Article in journal (Refereed)
  • 13.
    Sjöstrand, Björn
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Barbier, Christophe
    BillerudKorsnäs AB, R&D Gruvön, Solna, Sweden.
    Ullsten, Henrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Nilsson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Dewatering of Softwood Kraft Pulp with Additives of Microfibrillated Cellulose and Dialcohol Cellulose2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 3, p. 6370-6383Article in journal (Refereed)
    Abstract [en]

    The addition of nano-and micro-fibrillated cellulose to conventional softwood Kraft pulps can enhance the product performance by increasing the strength properties and enabling the use of less raw material for a given product performance. However, dewatering is a major problem when implementing these materials to conventional paper grades because of their high water retention capacity. This study investigated how vacuum dewatering is affected by different types of additives. The hypothesis was that different types of pulp additions behave differently during a process like vacuum suction, even when the different additions have the same water retention value. One reference pulp and three additives were used in a laboratory-scaled experimental study of high vacuum suction box dewatering. The results suggested that there was a linear relationship between the water retention value and how much water that could be removed with vacuum dewatering. However, the linear relationship was dependent upon the pulp type and the additives. Additions of micro-fibrillated cellulose and dialcohol cellulose to the stock led to dewatering behaviors that suggested their addition in existing full-scale production plants can be accomplished without a major redesign of the wire or high vacuum section.

  • 14.
    Stahl, Magnus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Granstrom, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Improvement of Wood Fuel Pellet Quality Using Sustainable Sugar Additives2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 2, p. 3373-3383Article in journal (Refereed)
    Abstract [en]

    The global production and use of wood fuel pellets has increased significantly in recent years. The raw material and the energy required to dry it are the main production costs. Therefore, it is crucial to minimize energy consumption, production costs, and the environmental impact associated with wood pellets. However, these changes should not negatively affect the quality of the pellets. One way to achieve these goals is to use additives. This work investigates how different types of sugar additives affect both the energy needed by the pellet press and the durability and oxidation of the produced pellets. When sugar was used as an additive, the energy use was practically unaffected. When molasses and SSL were added, a small decrease in energy use was observed (6 to 8%) for admixtures up to 1 wt.%; however, when more molasses was added, the energy use increased. Using these additives increased the bulk density (7 to 15 %) and durability (10 to 20 %) of the pellets. The storage of the pellets also caused a small increase in durability (1 to 3 %). Volatile organic compounds were produced as oxidation peaks within the first two months of storage; thereafter, the peaks tapered off.

  • 15.
    Östberg, Linda
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Håkansson, Helena
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Germgård, Ulf
    Karlstad University, Faculty of Technology and Science.
    Some aspects of the reactivity of pulp intended for high-viscosity viscose2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 1, p. 743-755Article in journal (Refereed)
    Abstract [en]

    The original objective of this study was to reduce the consumption of carbon disulphide in the preparation of high-viscosity viscose by pre-treating two softwood pulps with enzymes prior to the viscose stages. Reactivity can, however, be measured in different ways and the methods used in this study are Fock´s test of the pulp and the gamma number of the viscose solution prior to regeneration. It was found that whilst the reactivity of a pulp that had been subjected to enzyme pretreatment increased according to Fock´s test, it did not increase when the gamma number obtained in a standardized viscose preparation process was used. This unexpected difference that was discovered between the two reactivity tests made it difficult to analyze the impact of the enzyme stage on reactivity; the underlying reasons for the different reactivity results obtained were therefore investigated first. The conclusion that may be drawn from this investigation is that Fock´s test measures the extent to which carbon disulphide reacts with a pulp sample during a standardized test whereas the gamma number measures the resulting degree of xanthate substitution on the cellulose backbone. These two reactivity tests are thus not totally correlated. It was concluded that the gamma number was the more relevant of the two tests since it reflects the dissolution ability of a pulp in the viscose preparation, which is a very basic property of viscose. A higher gamma number also means that the coagulation time in the spinning process is prolonged; this is beneficial as it can be used to increase the tenacity of the viscose fibres. Measuring the reactivity according to Fock´s test, on the contrary, provides more dubious results as the test has no undisputed correlation to the viscose preparation process.

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