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  • 1.
    Andersson, Sofia
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    Bengtsson, Andreas
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi. KTH Royal institute of technology, Sweden.
    Åkerström, Mårten
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    The impact of inorganic elements on lignin‐based carbon fibre quality2018Ingår i: 15th European workshop on lignocelllulosics and pulp: Proceedings for poster presentations, 2018, s. 119-122Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The influence of inorganic elements on lignin ‐based carbon fibre (CF) quality was studied using sulphates of Na +, K+, Mg2+, Fe2+, Al3+. The metal sulphates were added to wet spun prefibres made from softwood kraft lignin (SKL):cellulose (70:30) and melt spun prefibres made from low molecular mass SKL. An increase in concentration from 0.1 w% to about 0.4 w% did neither affect the mechanical properties nor the morphology as observed by SEM. In contrast, metal sulphates added to the initial 0.45 w% to a total range 1.5 to 5.0 w%, was found detrimental to the melt spinning and to the final CF quality. Thus, the recommendation of <0.1 w% ash in kraft lignin may be exceeded, but more research is needed to establish the upper concentration limit.

  • 2.
    Baker, Darren A
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Sedin, Maria
    Södra skogsägarna ekonomisk förening, Sweden.
    Landmer, Alice
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Friman, Linda
    Södra skogsägarna ekonomisk förening, Sweden.
    Echardt, Linda
    Södra skogsägarna ekonomisk förening, Sweden.
    Structural carbon fibre from kraft lignin2017Ingår i: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017: NWBC 2017, Stockholm: RISE Bioekonomi , 2017, s. 65-67Konferensbidrag (Refereegranskat)
    Abstract [en]

    The GreenLight consortium is working to demonstrate a biobased, renewable and economically viable carbon fibre from lignin. The aim is to provide a basis for commercial production of lignin, lignin filaments, carbon fibre and carbon fibre composites. The most difficult boundary to success in the developing lignin as a precursor for continuous filament carbon fibre has been identified as melt extrusion of lignin. The consortium is working to develop a robust melt spinning platform for use up to the 1,000 filament scale. Methodical studies have been performed to examine lignin separation from differing black liquors derived from both softwood and hardwood and assess their viability in terms of thermal, compositional and structural properties. The move will then be made to pilot scale melt spinning at the 100 filament scale. The characteristics of some kraft lignin fractions obtained from the same Sodra Monsteras softwood kraft black liquor have been studied. The lignins were manufactured in quantities of approximately 10-20kg. Several variations of the LignoBoost process were used to provide lignins with improved melt spinning properties. The lignins were of high purity, each having low carbohydrate, extractives and inorganic contents. All four lignins could be melt spun and converted to carbon fibre.

  • 3.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    Improved yield of carbon fibres from cellulose and kraft lignin2018Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 12, s. 1007-1016Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To meet the demand for carbon-fibre-reinforced composites in lightweight applications, cost-efficient processing and new raw materials are sought for. Cellulose and kraft lignin are each interesting renewables for this purpose due to their high availability. The molecular order of cellulose is an excellent property, as is the high carbon content of lignin. By co-processing cellulose and lignin, the advantages of these macromolecules are synergistic for producing carbon fibre (CF) of commercial grade in high yields. CFs were prepared from precursor fibres (PFs) made from 70:30 blends of softwood kraft lignin (SW-KL) and cellulose by dry-jet wet spinning with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) as a solvent. In focus was the impact of the molecular mass of lignin and the type of cellulose source on the CF yield and properties, while membrane-filtrated kraft lignin and cellulose from dissolving kraft pulp and fully bleached paper-grade SW-KP (kraft pulp) served as sources. Under the investigated conditions, the yield increased from around 22% for CF from neat cellulose to about 40% in the presence of lignin, irrespective of the type of SW-KL. The yield increment was also higher relative to the theoretical one for CF made from blends (69%) compared to those made from neat celluloses (48-51%). No difference in the mechanical properties of the produced CF was observed.

  • 4.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    Carbon Fibers from Lignin-Cellulose Precursors: Effect of Stabilization Conditions2019Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, nr 9, s. 8440-8448Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is an increasing demand for lightweight composites reinforced with carbon fibers (CFs). Due to its high availability and carbon content, kraft lignin has gained attention as a potential low-cost CF precursor. CFs with promising properties can be made from flexible dry-jet wet spun precursor fibers (PFs) from blends (70:30) of softwood kraft lignin and fully bleached softwood kraft pulp. This study focused on reducing the stabilization time, which is critical in CF manufacturing. The impact of stabilization conditions on chemical structure, yield, and mechanical properties was investigated. It was possible to reduce the oxidative stabilization time of the PFs from about 16 h to less than 2 h, or even omitting the stabilization step, without fusion of fibers. The main reactions involved in the stabilization stage were dehydration and oxidation. The results suggest that the isothermal stabilization at 250 °C override the importance of having a slow heating rate. For CFs with a commercial diameter, stabilization of less than 2 h rendered in tensile modulus 76 GPa and tensile strength 1070 MPa. Impregnation with ammonium dihydrogen phosphate significantly increased the CF yield, from 31-38 to 46-50 wt %, but at the expense of the mechanical properties.

  • 5.
    Bialik, Marta
    et al.
    RISE., Innventia.
    Sedin, Maria
    Theliander, H.
    Application of the pitzer method in estimating the properties of black liquor solutions: A summary2010Ingår i: International Chemical Recovery Conference, 2010, Vol. 2, s. 16-23Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Pitzer method for calculating activity coefficients in aqueous electrolyte solutions has been widely applied to modeling the properties of numerous industrial systems. Its use in hot, concentrated solutions, an example being black liquor from kraft pulping process, has nevertheless been limited mainly due to a lack of suitable interaction parameters. This paper summarizes our work in implementing the Pitzer method into modeling of double salt solubilities and boiling point rise in industrial black liquors. Two solubility models: for burkeite, Na 2Co 22Na 2S0 4 and for (sodium sulfate) dicarbonate, 2Na 2CO 3Na 2S0 4 were developed based on literature and experimental data, respectively. Boiling point rise was modeled in two types of black liquor: ordinary and lignin-lean after a lignin precipitation stage. The paper also presents our study on a method for estimating new Pitzer interaction parameters in hot solutions of sodium lactate using the boiling point rise data.

  • 6. Niemi, Harri
    et al.
    Kallioinen, Mari
    Puro, Liisa
    Danielsson, Sverker
    RISE., Innventia.
    Sedin, Maria
    RISE., Innventia.
    Mänttäri, Mika
    Evaluation of degradation tendency of wood polymeric compounds in wood extract at high temperature2015Ingår i: 18th International Symposium on Wood, Fiber and Pulping Chemistry, September 9-11, 2015, Vienna, 2015, s. 382-384Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This study aims to find out the effect of exposure time and process conditions on changes of the wood extract from hot water extraction, when it is exposed at high temperature after the extraction. This information is needed, when an intensified process combining extraction and separation is designed for recovery of hemicelluloses, because in a process of this kind theextract is exposed to high temperature also after the extraction step.The study was done with two different extract batches. The extract 1 was produced at 140 oC (circulation time 2 hours) and the extract 2 at 160 oC (circulation time 1.5 hours). Samples of these extracts were exposed to 120 oC and 160 oC for different timeperiods between 15 and 285 minutes (0.25-4.75 hours).Based on this study it seems that processing of the extract at high temperature would likely to be safe at 120 oC for several hours, while at 160 oC no longer than 2-3 hours processing times can be recommended. The 4 hours exposure to 120 oC caused a clear decrease (20-30%) only in lignin amount (based on UV absorbance) but hemicellulose, monosaccharide and solid concentrations were not significantly affected. The five hours exposure to 160 oC caused remarkable hemicellulose losses (%). In addition, significant changes could be observed in lignin and solids content of the extracts.

  • 7.
    Sewring, Tor
    et al.
    Chalmers University of Technology, Sweden; KTH Royal Institute of Technology, Sweden.
    Zhu, Weizhen
    Chalmers University of Technology, Sweden; Stora Enso; Sweden.
    Sedin, Maria
    RISE., Innventia.
    Theliander, Hans
    Chalmers University of Technology, Sweden; KTH Royal Institute of Technology, Sweden.
    Estimation of the deprotonation degree of phenolic groups on kraft lignin2015Ingår i: NWBC 2015: The 6th Nordic Wood Biorefinery Conference, Espoo: VTT , 2015, s. 442-449Konferensbidrag (Refereegranskat)
    Abstract [en]

    Research has been undertaken into the deprotonation degree of the phenolic groups on softwood kraft lignin in black liquor. An attempt was made to mathematically model the ion concentration distributions around lignin fragments in black liquor by studying the possibility of using a modified Poisson-Boltzmann cell model and extending the validity of this model by extrapolating the valid ionic concentration range using the Pitzer method. The model has been utilised to predict the pH dependent deprotonation degree under various conditions that are relevant to the LignoBoost process. It has been demonstrated that the pH and temperature strongly affected the deprotonation degree of phenolic groups on kraft lignin. The effect of the molecular weight of lignin and a small increase in ionic strength on the deprotonation degree was very small in black liquor systems of high ionic strength. It was observed that the pH at the surface of lignin macromolecules was approximately the same in black liquor systems of high ionic strength.

  • 8.
    Sewring, Tor
    et al.
    Chalmers University of Technology, Sweden.
    Zhu, Weizhen
    Chalmers University of Technology, Sweden.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Theliander, Hans
    KTH Royal Institute of Technology, Sweden; Chalmers University of Technology, Sweden.
    Predictions of Pair Interaction Potentials between Kraft Lignin Macromolecules in Black Liquors by Utilization of a Modified Poisson-Boltzmann Approach2019Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, nr 8, s. 3427-3439Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this investigation, a modified Poisson-Boltzmann approach has been used to estimate the mean ion concentration distributions of ionic species present in black liquors around charged kraft lignin macromolecules at industrially relevant conditions. The distributions were utilized to predict the double layer repulsion and, further, predict the overall pair interaction potentials between two kraft lignin macromolecules or particles immersed in the black liquor electrolyte. The properties of softwood black liquors were used as input data to the model. The numerical results predicted the pair interaction potentials to remain repulsive up to salt concentrations of about 2.5 M at pOH 1. The critical coagulation concentration of salt was predicted to decrease as the pOH of the black liquor was increased. The predictions at 65 °C and moderate levels of pOH (3.5) and salt concentration (1.9 M) were found to be in good agreement with previous observations reported in the literature.

  • 9.
    Ziesig, Rufus
    et al.
    RISE., Innventia.
    Sedin, Maria
    RISE., Innventia.
    Tomani, Per
    RISE., Innventia.
    Theliander, Hans
    RISE., Innventia. Chalmers University of Technology, Sweden.
    Production of a pure lignin product, Part 3: Distribution and removal of inorganics from softwood lignin2015Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 2, s. 199-206Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Future high value lignin-based products, such as carbon fibers, require a lignin raw material essentially free from inorganic impurities. Lignin of low inorganic content can be separated from kraft black liquor by the LignoBoost process. This laboratory scale study focuses on the effect of process parameters, such as pH and retention time in re-suspension, on the content of inorganic impurities in the LignoBoost lignin. Black liquor from pulping of softwood was used in this study. Specific attention was paid to the elements Na, K, Al, Ba, Ca, Fe, Mg, Mn and Si. It was found that the softwood lignin contained significantly less Ca, resulting in lower ash content, than eucalyptus lignin separated in earlier studies made in this series. Inorganic particles, containing for example Ca-O and Na-Al-Si, were observed in the washed lignin. Prolonged retention time in the re-suspension stage reduced the content of Ca, Mn, Mg, Fe and Si in the washed lignin. A reduction of the content by 30-50% after 24 h was possible. The rate at which these elements are removed from the agglomerates was found to be dependent on the mixing conditions, which indicates that the mass transfer in the liquid film around the particles is of importance for the total mass transfer resistance.

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