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  • 201.
    Glenne, Emelie
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Ohlen, Kristina
    AstraZeneca R&D, Innovat Med, Resp Inflammat & Autoimmun, S-43183 Molndal, Sweden..
    Leek, Hanna
    AstraZeneca R&D, Innovat Med, Resp Inflammat & Autoimmun, S-43183 Molndal, Sweden..
    Klarqvist, Magnus
    AstraZeneca R&D, Innovat Med, Resp Inflammat & Autoimmun, S-43183 Molndal, Sweden..
    Samuelsson, Jorgen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Fornstedt, Torgny
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    A closer study of methanol adsorption and its impact on solute retentions in supercritical fluid chromatography2016Ingår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1442, s. 129-139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface excess adsorption isotherms of methanol on a diol silica adsorbent were measured in supercritical fluid chromatography (SFC) using a mixture of methanol and carbon dioxide as mobile phase. The tracer pulse method was used with deuterium labeled methanol as solute and the tracer peaks were detected using APCI-MS over the whole composition range from neat carbon dioxide to neat methanol. The results indicate that a monolayer (4 angstrom) of methanol is formed on the stationary phase. Moreover, the importance of using the set or the actual methanol fractions and volumetric flows in SFC was investigated by measuring the mass flow respective pressure and by calculations of the actual volume fraction of methanol. The result revealed a significant difference between the value set and the actually delivered volumetric methanol flow rate, especially at low modifier fractions. If relying only on the set methanol fraction in the calculations, the Methanol layer thickness should in this system be highly overestimated. Finally, retention times for a set of solutes were measured and related to the findings summarized above concerning methanol adsorption. A strongly non-linear relationship between the logarithms of the retention factors and the modifier fraction in the mobile phase was revealed, prior to the established monolayer. At modifier fractions above that required for establishment of the methanol monolayer, this relationship turns linear which explains why the solute retention factors are less sensitive to changes in modifier content in this region.

  • 202.
    Govindarajan, Venkatesh
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Nyflött, Åsa
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Bonnerup, Chris
    Stora Enso.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    An economic-environmental analysis of selected barrier coating materials used in packaging food products: A Swedish case study2018Ingår i: Environment, Development and Sustainability, ISSN 1387-585X, E-ISSN 1573-2975, Vol. 20, nr 4, s. 1483-1497Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of a barrier coating in food packaging is primarily to increase the shelf life of the foodstuff contained within the packaging, preserve its colour, odour, taste and quality, and thereby reduce food wastage (both at retail outlets and households). While most publications hitherto have compared packaging and barrier-coating materials on the basis of their environmental impacts alone, this paper adopts a more holistic approach by factoring in the economic aspect as well. Four barrier material alternatives—starch, polyethylene, EVOH + kaolin and latex + kaolin are analysed. Two well-defined end-of-life handling scenarios, relevant to Sweden, are: one in which everything except starch is recycled, with starch being composted, and the other in which everything is incinerated. Among the several environmental impact categories which can be analysed, this paper considers only global warming. Two approaches are tested to combine the economic and environmental aspects—normalisation, weighting and aggregating on the one hand, and using the carbon tax to internalise the externality caused by GHG emissions on the other. For the set of weighting factors obtained thanks to a survey conducted by the authors (40.6% for environmental and 59.4% for economic), starch emerges as the most sustainable alternative, followed by polyethylene for both the end-of-life handling scenarios. This tallies with the result obtained by using the carbon tax for internalisation of the externality. The case study, methodology and results presented in this paper, will hopefully be a springboard for more detailed studies of this nature, under the umbrella of sustainability.

  • 203. Granevald, Rickard
    Studies of Vacuum Dewatering on Low Grammage Paper Webs2003Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    A laboratory scale apparatus to simulate high-vacuum dewatering of low grammage paper sheets, typically for tissue products has been constructed. Vacuum level, vacuum pulse dwell time and frequency of single vacuum pulses are in the range typical for a Through Air Drying (TAD) tissue machine. The vacuum pulse dwell time was varied from 0.5 to 3 ms and the vacuum level from 10 to 60 kPa. For the 50 and 60 kPa series the solids contents for all curves leveled out at 23 and 24 % after about 2 ms. The laboratory apparatus has been validated by comparing results with data obtained from a pilot paper machine. The laboratory data correlated well with the data from the pilot paper machine.



    Using the new apparatus, the effects of fabric parameters on sheet solids content during the vacuum dewatering of a low grammage sheet has been studied. The pressure drop over the fabric did not explain the difference in sheet solids content among the fabrics. Instead caliper, void volume and air permeability were shown to have a great impact on the dewatering of the sheet.



    The correlation between sheet solids content and caliper, void volume and air permeability may be due to the fact that these fabric parameters control the amount of water that the fabrics can hold during a vacuum pulse and that can be rewetted into the sheet after a vacuum pulse. The theory of rewetting was supported in several experiments and further strengthened in comparisons with the literature.



    If fabric caliper could be reduced to zero, the sheet solids content theoretically should level out at 28-34 % after a vacuum pulse dwell time of 0.5 ms at a vacuum level of 30 kPa in the case of 17 g/m2 sheets made of kraft pulp. That is expected in accordance to the theory of viscous drag and implies that dewatering by viscous drag between the penetrating air and the water in the intra-fiber pores start already after a vacuum pulse dwell time of 0.5 ms. The difference in the actual sheet solids content after a vacuum pulse and the theoretical solids content of 28-34 % can be explained as being due to rewetting from the fabric to the sheet

  • 204. Granevald, Rickard
    Vacuum dewatering of low-grammage paper webs and fabrics2005Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 205. Granevald, Rickard
    et al.
    Nilsson, Lars
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Stenström, Stig
    Evaluation of different forming fabric parameters during vacuum dewatering2004Ingår i: Nordic Pulp and Paper Research Journal, 19(4):481-486Artikel i tidskrift (Refereegranskat)
  • 206.
    Granstrom, Karin
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Javeed, Atif
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Emissions from sawdust in packed moving bed dryers and subsequent pellet production2016Ingår i: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 34, nr 3, s. 258-266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study quantifies emissions of hydrocarbon terpenes from the drying of sawdust in packed moving bed dryers, through the production chain to the finished pellets, and determines the parameters suitable for emission control. The terpene content in softwood sawdust and pellets was analyzed using gas chromatography. The distribution of VOC emissions over the bed was measured with a flame ionization detector. After drying, 30-40% of the initial terpenes remain in the wood, 20-30% remain after grinding, and 10-15% remain after pelleting. Dryer emissions correlate with residence time and final sawdust moisture content. Pellet press emissions correlate with pellet moisture content.

  • 207.
    Granström, Karin
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Williams, Helen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Berghel, Jonas
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Frodeson, Stefan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Renström, Roger
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Sandberg, Maria
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Ståhl, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    The importance of a holistic perspective when investigating agricultural products as additives in sustainable pellets development2012Konferensbidrag (Refereegranskat)
  • 208. Greschik, Thomas
    et al.
    Guo, Sanchuan
    Basta, Jiri
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Johansson, Dan
    Optimization of the cooking conditions when producing high quality eucalyptus pulps using a design of experiments (DoE) approach2008Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 209.
    Grob, Stefan
    et al.
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Bartynski, Andrew N.
    Humboldt Univ, Inst Phys, D-12489 Berlin, Germany..
    Opitz, Andreas
    Univ So Calif, Dept Chem, Dept Chem Engn, Los Angeles, CA 90089 USA..
    Gruber, Mark
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Grassl, Florian
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Meister, Eduard
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Linderl, Theresa
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Hoermann, Ulrich
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Lorch, Christopher
    Univ Tubingen, Inst Angew Phys, D-72076 Tubingen, Germany..
    Moons, Ellen
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Schreiber, Frank
    Univ Tubingen, Inst Angew Phys, D-72076 Tubingen, Germany..
    Thompson, Mark E.
    Humboldt Univ, Inst Phys, D-12489 Berlin, Germany..
    Bruetting, Wolfgang
    Univ Augsburg, Inst Phys, D-86135 Augsburg, Germany..
    Solvent vapor annealing on perylene-based organic solar cells2015Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 30, s. 15700-15709Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Diindenoperylene (DIP) and tetraphenyldibenzoperiflanthene (DBP) are two commonly used donor materials in organic solar cell devices. Despite their structural similarities, DIP films are crystalline, exhibiting good charge and exciton transport, whereas DBP films are amorphous and have lower carrier mobility and a short exciton diffusion length. However, DBP reveals a distinctly higher absorption due to the lying orientation of its transition dipole moments. In this paper, we investigate the influence of solvent vapor annealing (SVA) on the solar cell performance of both materials. In general, SVA induces a partial re-solubilization of the material leading to enhanced crystallinity of the treated layer. For DBP, extended annealing times result in a strong aggregation of the molecules, creating inhomogeneous layers unfavorable for solar cells. However, in DIP cells, SVA leads to an increase in fill factor (FF) and also a slight increase in short-circuit current density (JSC) due to interface roughening. The best results are obtained by combining solvent vapor annealed DIP layers with strongly absorbing DBP and C-70 on top. Through this device architecture, we obtain the same increase in FF in addition to a higher gain in J(SC), elevating the power conversion efficiency by a factor of 1.2 to more than 4%.

  • 210.
    Guo, Sanchuan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper, Paper Surface Centre.
    Heijnesson-Hulten, Anette
    Basta, Jiri
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Wang, Qianqian
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Optimum Bamboo Kraft Cooking - The Influence of The Cooking Conditions on The Pulp and Fibre Properties2010Ingår i: O Papel 0031-1057, Vol. 71, nr 7, s. 63-75Artikel i tidskrift (Refereegranskat)
  • 211. Guo, Sanchuan
    et al.
    Zhan, Huaiyu
    Johansson, Dan
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Basta, Jiri
    Blom, Christian
    Greschik, Thomas
    Optimization of bamboo pulping using factorial design2006Konferensbidrag (Refereegranskat)
  • 212.
    Gustavsson, Maria
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    The Significance of Liquor-to-Wood Ratio on the Reaction Kinetics of Spruce Sulphate Pulping2007Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    In 1957 Vroom presented an article that dealt with the kinetics of the sulphate cook. He showed that the lignin dissolution exhibited a temperature/time dependency that could be explained by the Arrhenius equation and that the reaction was of first order with respect to lignin. However, even before Vroom introduced the H-factor all wood components were assumed to react according to a first order reaction. In recent years progresses in this area have been made. Lignin for example is nowadays considered to dissolve during three parallel first order reactions, all with differences in activation energies.

    When the kinetics are evaluated, several cooking series at different temperatures and concentrations of active cooking chemicals are needed. The data points obtained are then fitted into some equation. If the concentration of the active cooking chemicals is constant, the activation energies and the chemical dependency for the dissolution of wood components can easily be found. In order to simplify the evaluations of the kinetics, very high liquor-to-wood ratios are sometimes used, often as high as 50:1 or even 75:1. In this manner, the chemical concentrations are almost constant during the cook. The problem is that in the normal industrial cook where the liquor-to-wood ratio is about 4:1, the chemical concentration is not constant. This is due mostly to the alkali consumption that takes place in the cook for example when neutralising the acidic groups in the hemicelluloses.

    A disadvantage with high liquor-to-wood ratios is the high dilution of the dissolved organic matter. A high concentration of dissolved lignin boosts the dissolution of the remaining lignin in the wood residue and xylan can redeposit on the fibres when its concentration in the cooking liquor is high.

    The aim of this project was to describe how different liquor-to-wood ratios influence the kinetics during sulphate cooking of spruce.

  • 213. Hallberg, Erik
    et al.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Rättö, Peter
    Thuvander, Fredrik
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Odeberg Glasenapp, Astrid
    Evaluation of Pressure Variations Generated During Flexographic Post-Print of Corrugated Board and Effects of Mechanical Properties of Printing Forms on Printed Banding2004Ingår i: 56th Annual TAGA Technical Conference Proceedings, TAGA, Pennsylvania, U.S.A, 2004, s. 114-126Konferensbidrag (Refereegranskat)
  • 214. Hallberg, Erik
    et al.
    Odeberg Glasenapp, Astrid
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Quantification of Banding on Printed Corrugated Board Using Spatial Frequency Analysis2005Ingår i: Packaging Tecnology and Science, Vol. 18, nr 2, s. 89-95Artikel i tidskrift (Refereegranskat)
  • 215. Hallberg, Erik
    et al.
    Rättö, Peter
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Thuvander, Fredrik
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Odeberg Glasenapp, Astrid
    Flexo Print of Corrugated Board: Mechanical Aspects of the Plate and Plate Mounting Materials2005Ingår i: TAGA Journal, Vol. 2, s. 16-28Artikel i tidskrift (Refereegranskat)
  • 216. Hallberg Hofstrand, Erik
    En Långrandig Problematik: Tryckformens Inverkan på Tryckresultatet vid Flexotryck på Wellpapp2005Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 217. Hallberg Hofstrand, Erik
    Flexo Print of Corrugated Board: Mechanical Aspects of the Plate and Plate Mounting Materials2003Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 218. Hallberg Hofstrand, Erik
    Flexografiskt Direkttryck av Wellpapp och Tryckformens Inverkan på Tryckresultatet2003Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 219. Hallberg Hofstrand, Erik
    Flexographic Post-Printing of Corrugated Board2006Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 220.
    Hallberg Hofstrand, Erik
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Flexographic Post-Printing of Corrugated Board: Contact Mechanics and Print Quality2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    As the corrugated board industry strives to produce products with a higher print quality in the converting stage, there is a need for a greater understanding of the factors influencing the final print quality and how we perceive the print. In this work, a method for quantifying the print quality of printed corrugated board is presented as well as methods that quantitatively characterize the mechanical interaction between the printing form and the corrugated board in the printing nip. The results of investigations addressing the impact of the mechanical properties of the printing form on ink transfer are also presented.

    A band-pass image analysis method adapted to the spatial wavelength of B-flute corrugated board was used to quantify the print quality on the board in terms of print banding. The findings were substantiated by a perceptual evaluation which showed a high correlation to the instrumental quantification.

    The main cause of print banding is a higher local contact pressure on the fluting tips than in the fluting valleys, which leads to a higher ink transfer to the fluting tips. A greater difference between the local contact pressure on the fluting tips than in the fluting valleys generated a higher degree of banding. The difference in local contact pressure as well as nip force variations could be measured using the proposed methods to characterize the interaction between the printing form and the corrugated board. The difference in local contact pressure was highly dependent on the mechanical properties of the components of the printing form. An increase in the stiffness in compression mode and in the bending stiffness of the printing form led to a smaller contact area in the printing nip and consequently a higher external pressure on the ink, resulting in an overall higher ink transfer but also a higher degree of banding.

    The influence of the mechanical properties of the printing form components was supported by the results of numerical simulations of the contact between the printing form and the corrugated board. Contact area, pressure level and texture of the local contact pressure were compared with measurements of local contact pressures for different printing forms and the results showed a high degree of agreement. Numerical simulations could thus predict the print quality achieved with different printing forms under different printing conditions.

  • 221. Hallberg Hofstrand, Erik
    Flexotryck på Wellpapp2005Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 222. Hallberg Hofstrand, Erik
    Impact of Different Printing Forms on Banding on Post-Printed Corrugated Board2005Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 223. Hallberg Hofstrand, Erik
    Print Quality of Post-Printed Corrugated Board2004Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The use of printed corrugated board as a packaging material has evolved from a brown box with This Side Up stamped on it to an advertiser efficient in the customerÕs critical moment of purchase. The demand for quality printing of post-printed corrugated board is growing.



    The purpose of this study was to gain a better knowledge of post-printing of corrugated board and quantification of banding on printed corrugated board. Post-printing trials which also included measurements of pressure variations in the printing nip were performed. B-flute corrugated board and several differently designed printing forms, belonging to the so-called thin-plate technology, were used in the trials. The evaluation of the results was focused on the contact mechanics of the ink transfer in the nip; between the ink-covered printing form and the corrugated board. The influence of the mechanical properties of the printing forms on print quality and lateral pressure variations in the printing nip were investigated. It was shown that the compressibility modulus and the bending stiffness of the printing form affected the pressure variations and ink transfer. The properties thus affect the print quality. Furthermore, a proposal for the instrumental evaluation of banding on printed B-flute corrugated board is presented. A good correlation was found between the instrumental results and the perceptual ratings.

  • 224. Hallberg Hofstrand, Erik
    Research Summary: Banding on Flexographic printed corrugated board: Important clues to solve an annoying problem2006Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Summary of research results based on the articles Quantification of banding on printed corrugated board using spatial frequency analysis by Erik Hallberg, Astrid Odeberg Glasenapp and Magnus Lestelius in Packaging Technology and Science 18, 89-95 (2005) and Dynamic measurements of nip force variations during post-printing of corrugated board by Erik Hallberg Hofstrand, Magnus Lestelius and Peter Rättö in Nordic Pulp and Paper Research Journal 21(1), 111-114 (2006)

  • 225. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    The Influence of Printing Forms Mechanical Properties on Flexographic Post-Printing2004Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 226. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Rättö, Peter
    Dynamic measurements of nip force variations during post-printing of corrugated board2006Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, nr 1, s. 111-114Artikel i tidskrift (Refereegranskat)
  • 227. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Rättö, Peter
    Dynamic Measurements of Nip Force Variations during Post-Printing of Corrugated Board2006Ingår i: Nordic Pulp & Paper Research Journal, 21(1), 111-114 (2006)Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method has been developed in order to measure nip force variations during flexographic post-printing of corrugated board. This method can be used to study the influence of the nip mechanics on the final print quality

  • 228. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Rättö, Peter
    Thuvander, Fredrik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Odeberg Glasenapp, A.
    Evaluation of Pressure Variations Generated During Flexographic Post-Print of Corrugated Board and Effects of Mechanical Properties of Printing Forms on Printed Banding2004Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 229. Hallberg Hofstrand, Erik
    et al.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Rättö, Peter
    Thuvander, Fredrik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Odeberg Glasenapp, A
    Flexo Print of Corrugated Board: Mechanical Aspects of the Plate and Plate Mounting Materials2005Ingår i: TAGA Journal, vol.2,pp.16-28Artikel i tidskrift (Refereegranskat)
  • 230. Hallberg Hofstrand, Erik
    et al.
    Odeberg Glasenapp, A.
    Lestelius, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Quantification of Banding on Printed Corrugated Board using Spatial Frequency Analysis2005Ingår i: Packaging Technology and Science,vol 18,no.2,pp.85-95, 2005Artikel i tidskrift (Refereegranskat)
  • 231. Hallberg Hofstrand, Erik
    et al.
    Rättö, Peter
    Impact of Different Printing Forms on Print Banding on Post-Printed Corrugated Board: Experimental and Numerical Investigations2006Konferensbidrag (Refereegranskat)
  • 232. Hallberg Hofstrand, Erik
    et al.
    Rättö, Peter
    Impact of Different Printing Forms on Printed Banding on Post-Printed Corrugated Board: Experimental and Numerical Investigation2006Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 233.
    Hallbäck, Nils
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Korin, Christer
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Paper Surface Centre.
    Vähä-Nissi, Mika
    Seppänen, Rauni
    Laine, Christiane
    Influence of paperboard on bond formation and strength of adhesive joint2009Konferensbidrag (Refereegranskat)
    Abstract

    Knowledge about the glueability of fiber-based materials is limited. Factors affecting the adhesive joint between adhesive and paperboard are presented here through two cases: strength of hot melt adhesive joint and consolidation of dispersion adhesive. The hot melt joint was investigated by Y-peel testing, while shear testing was applied for dispersion adhesives. A set of supplementing tools was used to understand the adhesive joints, their development and failure. The results show, for example, the importance of paperboard roughness on the hot melt joint strength. Formation of an adhesive joint with dispersion adhesives is affected by the rheological properties of the adhesive layer and the structure and absorbation properties of the board surface. Both case studies indicate that it can actually be better to apply the adhesive first on a rough surface and the press the smooth surface on the adhesive, which is in contrast with the common practice today

  • 234.
    Hansson, Björn
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Evaluation of Compression Testing and Compression Failure Modes of Paperboard: Video analysis of paperboard during short-span compression and the suitability of short- and long-span compression testing of paperboard2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The objectives of the thesis were to find the mechanisms that govern compression failures in paperboard and to find the link between manufacturing process and paperboard properties. The thesis also investigates two different test methods and evaluates how suitable they are for paperboard grades. The materials are several commercial board grades and a set of hand-formed dynamic sheets that are made to mimic the construction of commercial paperboard. The method consists of mounting a stereomicroscope on a short-span compression tester and recording the compression failure on video, long-span compression testing and standard properties testing. The observed failure modes of paperboard under compression were classified into four categories depending on the appearance of the failures. Initiation of failure takes place where the structure is weakest and fiber buckling happens after the initiation, which consists of breaking of fiber-fiber bonds or fiber wall delamination. The compression strength is correlated to density and operations and raw materials that increase the density also increases the compression strength. Short-span compression and Long-span compression are not suitable for testing all kinds of papers; the clamps in short-span give bulky specimens an initial geometrical shape that can affect the given value of compression strength. Long-span compression is only suitable for a limited range of papers, one problem with too thin papers are low wavelength buckling. 

  • 235.
    Hedenqvist, Mikael
    et al.
    Fibre and polymer technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Johansson, Eva
    Department of Plant Breeding, The Swedish University of Agricultural Sciences, Alnarp, Sweden.
    Newson, William
    Department of Plant Breeding, The Swedish University of Agricultural Sciences, Alnarp, Sweden.
    Gallstedt, Mikael
    Innventia AB, Stockholm, Sweden.
    Kuktaite, Ramune
    The Swedish University of Agricultural Scienc, Alnarp, Sweden.
    Ullsten, Henrik
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Ture, Hasan
    Faculty of Marine Sciences, Ordu University, Ordu, Turkey.
    Extrusion of protein plastics2017Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253, artikel-id 449Artikel i tidskrift (Övrigt vetenskapligt)
  • 236. Hedlund, Alexander
    et al.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Some Aspects on the Kinetics of Etherification in the Preparation of CMC2007Ingår i: Cellulose, Vol. 14(2007)2,161-169Artikel i tidskrift (Refereegranskat)
  • 237.
    Hedström, Sofia
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Thermal energy recovery of low grade waste heat in hydrogenation process2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The waste heat recovery technologies have become very relevant since many industrial plants continuously reject large amounts of thermal energy during normal operation which contributes to the increase of the production costs and also impacts the environment.

    The simulation programs used in industrial engineering enable development and optimization of the operational processes in a cost-effective way.

    The company Chematur Engineering AB, which supplies chemical plants in many different fields of use on a worldwide basis, was interested in the investigation of the possibilities for effective waste heat recovery from the hydrogenation of dinitrotoluene, which is a sub-process in the toluene diisocyanate manufacture plant. The project objective was to implement waste heat recovery by application of the Organic Rankine Cycle and the Absorption Refrigeration Cycle technologies. Modeling and design of the Organic Rankine Cycle and the Absorption Refrigeration Cycle systems was performed by using Aspen Plus® simulation software where the waste heat carrier was represented by hot water, coming from the internal cooling system in the hydrogenation process. Among the working fluids investigated were ammonia, butane, isobutane, propane, R-123, R-134a, R-227ea, R-245fa, and ammonia-water and LiBr-water working pairs. The simulations have been performed for different plant capacities with different temperatures of the hydrogenation process. The results show that the application of the Organic Rankine Cycle technology is the most feasible solution where the use of ammonia, R-123, R-245fa and butane as the working fluids is beneficial with regards to power production and pay-off time, while R-245fa and butane are the most sustainable choices considering the environment.

  • 238.
    Heijnesson-Hulten, Anette
    et al.
    AkzoNobel, SE-44580 Bohus, Sweden..
    Guo, Sanchuan
    Karlstads universitet.
    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
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Impact of Drying on the Quality of Bamboo Kraft Pulps2013Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, nr 1, s. 1245-1257Artikel i tidskrift (Refereegranskat)
    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.

  • 239.
    Hellberg Lindqvist, Miriam
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Oxygen-dependent regulation of key components in microbial chlorate respiration2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Contamination of perchlorate and chlorate in nature is primarily the result of various industrial processes. The microbial respiration of these oxyanions of chlorine plays a major role in reducing the society’s impact on the environment. The focus with this thesis is to investigate the oxygen-dependent regulation of key components involved in the chlorate respiration in the gram‑negative bacterium Ideonella dechloratans. Chlorate metabolism is based on the action of the enzymes chlorate reductase and chlorite dismutase and results in the end products molecular oxygen and chloride ion. Up‑regulation of chlorite dismutase activity in the absence of oxygen is demonstrated to occur at the transcriptional level, with the participation of the transcriptional fumarate and nitrate reduction regulator (FNR). Also, the chlorate reductase enzyme was shown to be regulated at the transcriptional level with the possible involvement of additional regulating mechanisms as well. Interestingly, the corresponding chlorate reductase operon was found to be part of a polycistronic mRNA which also comprises the gene for a cytochrome c and a putative transcriptional regulator protein.

  • 240.
    Hellberg Lindqvist, Miriam
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Goetelen, T
    Fors, E
    Nilsson, Thomas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Rova, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Anoxic induction of the chlorite dismutase gene of Ideonella dechloratans is dependent of the fumarate and nitrate reduction regulatorManuskript (preprint) (Övrigt vetenskapligt)
  • 241.
    Hellberg Lindqvist, Miriam
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Nilsson, Thomas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Rova, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    An Fnr-type transcriptional regulator is responsible for anoxic up-regulation of chlorite dismutase in Ideonella dechloratansManuskript (preprint) (Övrigt vetenskapligt)
  • 242.
    Hellberg Lindqvist, Miriam
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Nilsson, Thomas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Rova, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Expression of the gene cluster for chlorate metabolism in the chlorate-respiring bacterium Ideonella dechloratans2012Ingår i: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1817, s. 157-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ideonella dechloratans is a facultative anaerobe able to use chlorate as a terminal electron acceptor under anaerobic conditions. Two enzymes are necessary for the decomposition of chlorate to chloride and molecular oxygen; chlorate reductase (Clr) and chlorite dismutase (Cld). The genes for these two enzymes are close to each other in the genome and form, together with a cytochrome c and a mob B gene, a gene cluster for chlorate metabolism. The localization of the cyt c gene suggests a function in electron transport during chlorate reduction but the corresponding protein has not been found. We have addressed the questions of how the expression of Cld and Clr is regulated during the aerob/anaerob switch and if the cyt c gene is expressed in I. dechloratans. The enzyme activities of Cld and Clr were measured in extracts from cells grown at different conditions; aerobically or anaerobically [1]. Both enzymes were found to be active in all samples and the activity increased upon transfer of the cells from aerobic to anaerobic conditions, by five times for Cld and more than 200 times for Clr. Relative mRNA levels of Cld and Clr were determined by qRT-PCR in RNA preparations from cells grown under the same conditions as for the enzyme activity measurements. mRNA from both genes was detected in all preparations but with ten times higher levels in samples from anaerobic conditions. This increase in mRNA level is on the same scale as the increase in enzyme activity for Cld but accounts for less than a tenth of the activity enhancement seen for Clr. A possible effect of chlorate was tested by the addition of chlorate under aerobic conditions but this resulted in neither increased enzyme activities nor increased mRNA levels. qRT-PCR was performed with primers specific for the cyt c gene and this gene was also found to be expressed at both aerobic and anaerobic conditions. In summary, the results show that chlorate respiration is activated by anaerobiosis but not by chlorate in I. dechloratans and that this activation occurs at the transcriptional level. Due to the much larger increase in enzyme activity compared to the increase in mRNA level, the activity of Clr also seems to be effected by other mechanisms. Detection of cyt c mRNA suggests that its gene product can be found and the function investigated.

  • 243.
    Hellström, Pia
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper. AkzoNobel.
    Heijnesson- Hultén, Anette
    AkzoNobel.
    Paulsson, Magnus
    AkzoNobel, Mid Sweden University.
    Håkansson, Helena
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    The effect of Fenton chemistry on the properties of microfibrillated cellulose (MFC)2013Övrigt (Övrigt vetenskapligt)
  • 244.
    Hellström, Pia
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013). AkzoNobel Pulp & Performance Chem, S-44580 Bohus, Sweden..
    Heijnesson-Hulten, Anette
    AkzoNobel Pulp & Performance Chem, S-44580 Bohus, Sweden..
    Paulsson, Magnus
    AkzoNobel Pulp & Performance Chem, S-44580 Bohus, Sweden.;Mid Sweden Univ, FSCN, S-85170 Sundsvall, Sweden..
    Hakansson, Helena
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    The effect of Fenton chemistry on the properties of microfibrillated cellulose2014Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 3, s. 1489-1503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A fully bleached birch kraft pulp was treated with acidic hydrogen peroxide in the presence of ferrous ions (Fenton's reagent) and thereafter treated mechanically in a colloid mill to produce a product containing microfibrillated cellulose (MFC). The produced MFC products were chemically and morphologically characterized and compared with MFC products produced without pretreatment as well as with enzymatic hydrolysis. Fenton treatment resulted in an increase in total charge and number of carbonyl groups while the intrinsic viscosity decreased. The Fenton treated pulps were easier to process mechanically i.e. they reached a higher specific surface area at a given mechanical treatment time and the MFC produced had a stable water-fibre suspension for at least 8 weeks compared to enzymatic pretreated pulps and pulps not subjected to any pretreatment.

  • 245.
    Hellström, Pia
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013). Akzo Nobel Pulp & Paper Performance Chem AB, Bleaching Chem Applicat RD&I, Bohus, Sweden..
    Heijnesson-Hulten, Anette
    Akzo Nobel Pulp & Paper Performance Chem AB, Bleaching Chem Applicat RD&I, Bohus, Sweden..
    Paulsson, Magnus
    Akzo Nobel Pulp & Performance Chem AB, Bleaching Chem Applicat RD&I, Bohus, Sweden.;Mid Sweden Univ, Sundsvall, Sweden..
    Håkansson, Helena
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    A comparative study of enzymatic and Fenton pretreatment applied to a birch kraft pulp used for MFC production in a pilot scale high-pressure homogenizer2016Ingår i: TAPPI Journal, ISSN 0734-1415, Vol. 15, nr 6, s. 375-381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microfibrillated cellulose (MFC) was produced in pilot scale from a bleached birch (Betula verrucosa) kraft pulp that was pretreated with either Fenton's reagent or with a combined mechanical and enzymatic method used at the Centre Technique du Papier (CTP; Grenoble, France). The change in fiber fibrillation during the homogenization treatment was monitored by analyzing the fiber and the fines content, size fractionation, rheological properties and visualization by light-and scanning electron microscopy (SEM). The Fenton pretreatment resulted in MFC suspensions that contained a high amount of small sized elements. After five passes through the high-pressure homogenizer, the amount of particles smaller than 20 mu m was 37% for the Fenton pretreated MFC compared to 13% for the enzymatically (endoglucanase) pretreated MFC. Altogether, the Fenton pretreatment enabled preparation of MFC with a higher degree of fibrillation after the same number of passes through the high-pressure homogenizer. Another option is to produce MFC of the same amount of fibrillation as after an enzymatic stage, but at significantly lower energy consumption.

  • 246.
    Hellström, Pia
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013). AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Heijnesson-Hulten, Anette
    AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden..
    Paulsson, Magnus
    AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.;Mid Sweden Univ, FSCN, SE-85170 Sundsvall, Sweden..
    Håkansson, Helena
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Fenton pre-treated microfibrillated cellulose evaluated as a strength enhancer in the middle ply of paperboard2014Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, nr 4, s. 732-740Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microfibrillated celluloses (MFCs), produced by various pre-treatments of a fully bleached birch kraft pulp, were evaluated as strength enhancers in test sheets representing the middle ply of paperboard. The furnish consisted of hydrogen peroxide bleached high temperature spruce chemithermomechanical pulp (HT-CTMP), MFC and a retention system containing cationic starch and an anionic silica sol. The MFC was prepared via a mechanical treatment in a colloid mill after pretreatment with Fenton's reagent, monocomponent endoglucanase or acidic hydrogen peroxide. Addition of 5% MFC, produced with Fenton pre-treatment, resulted in improved HT-CTMP properties with respect to increased tensile index (similar to 35%), z-directional strength (similar to 50%), tensile stiffness index (similar to 25%) compared to HT-CTMP test sheets prepared without MFC addition. The strength improvement was linearly correlated to the density of the tests sheet, to the surface area (BET) and to the surface charge of the enzymatic or chemically pre-treated MFCs.

  • 247. Hellström, Pia
    et al.
    Heijnesson-Hultén, Anette
    Paulsson, Magnus
    3FSCN, Mid Sweden University, SE-851 70 Sundsvall, Sweden.
    Håkansson, Helena
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    The effect of Fenton chemistry on the production of microfibrillated cellulose - characterization and paper board application2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    A fully bleached birch (Betula verucosa) sulphate pulp was treated with acidic hydrogen peroxide in the presence of ferrous iron (i.e. Fenton's reagent) and thereafter treated mechanically in a colloid mill to produce microfibrillated cellulose (MFC). The produced MFCs were chemically and morphologically characterized and compared with MFCs produced with enzymatic (monocomponent endoglucanase) pre-treatment (Figure 1). As a reference MFC produced with only acid pre-treatment was also included in the study.

    The Fenton pre-treatment increased the total charge of the fibres, decreased the viscosity and introduced new carbonyl groups. Addition of 10 and 50 kg/t hydrogen peroxide resulted in a yield loss of 2 and 4%, respectively. The enzymatic hydrolysis did not substantially change the total charge or the carbonyl group content of the pulp and did not release any organic material. The Fenton pre-treated pulps were easier to process mechanically, i.e. they reached a higher specific surface (BET) area and thereby a higher surface charge at a given mechanical treatment time, indicating a potential to reduce the energy demand in the final mechanical processing stage. The Fenton pre-treatment produced microfibrillated cellulose that in a water suspension (0.5% consistency) was stable with respect to sedimentation for at least eight weeks (Figure 2). Further, the Fenton pre-treatment gave a MFC product that contained a higher amount of small well fibrillated particles, as indicated by fractionation and scanning electron microscopy, compared with the enzymatic and acid pre-treatment methods studied.

  • 248.
    Hlisnikovska, Kristyna
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Järnström, Lars
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Polymer Adsorption on Nano Fibrillar Cellulose and its Effects on Suspension Rheology2011Ingår i: TAPPI International Conference on Nanotechnology for Renewable Materials 2011: Washington, DC, USA 6-8 June 2011, 2011, s. 649-Konferensbidrag (Refereegranskat)
  • 249.
    Hussain, Arif
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Using Chlorite Delignification to Simplify Characterization of Chemical Pulps2011Ingår i: Appita journal, ISSN 1038-6807, Vol. 64, nr 3, s. 257-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chlorite delignification is well known as a fast, efficient, and selective laboratory method for delignifying pulp samples (i.e. for removing the lignin without affecting the other components in the pulp). Less well known is the fact that this method can also be used to achieve high brightness in pulp samples in a single stage. Thus, bleaching becomes much simpler and can be performed more often. However, delignification should take place under conditions appropriate to each type of pulp in order to obtain pulps with high brightness and/or high pulp viscosity. Some examples are given in this paper. It should be noted that this method ought only to be used on laboratory-scale and that it is not suited to mill-scale bleaching, mainly due to the high chemical cost of bleaching

  • 250.
    Hämäläinen, Pyry
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Hallbäck, Nils
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Barbier, Christophe
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper (from 2013).
    Development and evaluation of a high-speed creping simulator for tissue2016Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, nr 3, s. 448-458Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An innovative creping simulator for tissue has been developed to meet the requirements set by both industrial needs, such as speed and process step duration, and research ambitions, such as flexibility for modifications and efficient operation. Some of these factors can be difficult to achieve with the previously introduced simulators. Lower speeds and much longer process step times can jeopardize results when, for instance, the drying time of chemicals is longer and the speed of creping is slower than in a tissue mill. The newly developed simulator has been used to investigate the effects of paper grammage, creping angle, temperature of dryer, speed and the horizontal force experienced during tissue creping. Results show good agreement with results of industrial-scale tissue production, with the exception of shrinkage which was greater. It was observed that the grammage influences the final thickness and the shrinkage of creped sheets, and that creping speed affects the creping frequency, thickness and shrinkage. The temperature of the surface of a sled mimicking the Yankee cylinder was shown to influence creping frequency and thickness. The horizontal friction force during creping appears to increase if drying temperature is lowered.

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