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  • 301.
    Karlsson, Pernilla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Swelling of Cellulose Fibrillar Matrices and Gels2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    One of the major challenges of today´s society is to find a sustainable way to create a living based on the resources on earth. It is a challenge that includes a transition from fossil-based materials to renewable/biodegradable raw materials and also the creation of an environmentally friendly circular material flow. In the search for renewable and biodegradable raw materials, the forest has gained renewed interest. In Sweden, 70 % of the area is covered with forest and, together with a long history of a sustainable forestry, this means that there are environmental and economic gains if this resource is utilized in a correct way and research and development into new wood-based materials has advanced significantly during the last decades. The wood component that has gained the most attention is cellulose and due to the ability of cellulose to act as a light-weight reinforcing component in composites and also due to the variability by which cellulose can be modified in order to obtain a wide range of useful properties. One advantage of cellulose-based materials is that they can be processed in water since the cellulose is hydrophilic and is softened by exposure to water. At the same time, this is one of the major drawbacks of cellulose-based materials since their properties deteriorate when exposed to water, whether as moist air or as condensed liquid. To optimize the use of cellulose fibers/fibrils/gels, knowledge of the effect on the inherent properties of cellulose in contact with water needs to be extended. This project has therefore focused on a fundamental understanding of the reasons behind the water uptake/swelling in a cellulose-rich fiber assembly immersed in water.

    The project has included the development and characterization of cellulose model materials in the form of gel (beads) and fibrillar (filaments) networks, for which the swelling was measured as a dimensional change in different aqueous environments. In one of the subprojects, the ion-induced swelling in different cellulose networks was measured on model materials and it was shown that the ion-induced contribution to the swelling was not only dependent on pH and salt concentration in the aqueous solution but also on the stiffness and structure of the network. Thermodynamic models describing gel swelling were used to separate and quantify the osmotic pressure associated with different factors contributing to the total osmotic pressure (ions, mixing and network) of never-dried gel beads. It was thus possible to identify the factor which had a dominant influence in the osmotic pressure and hence most important on the swelling of the systems. Never-dried gel beads showed that the network entropy was the most important factor controlling the swelling of the beads up to a volume fraction of cellulose of 35 %. Above this volume fraction the mixing entropy was found to dominate the swelling. It was also found that the distribution of the total osmotic pressure on these three factors was dependent on the network structure, as the distribution changed when the beads were dried and rewetted compared to the never-dried beads. Finally the de-watering ability of the gel beads in different environments was studied, and also after different modifications targeting the properties shown to have the most dominant effect on the osmotic swelling pressure (ion, mix and network). It was possible to quantify how the gel beads were dewatered to different degrees if e.g. hydrogen was chosen as the counter-ion to the carboxyl groups, if the polarity of the solution was lowered and if the structure of cellulose was changed. This information can, for example, be used to predict how nanocellulose based networks are dewatered under different conditions and this is essential for the preparation of materials based on cellulose nanofibrils.

    Publikationen är tillgänglig i fulltext från 2021-12-31 14:00
  • 302.
    Karlsson, Pernilla
    et al.
    KTH.
    Larsson, Tomas
    Innventia AB, Stockholm, Sweden..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Cellulose-based gel beads for quantifying the swelling behavior of plant fibers2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 303.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Fall, Andreas
    RISE Bioeconomy.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Bioeconomy.
    Wågberg, Lars
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    De-watering of Cellulose-based Gel Networks Targeting Different Factors Contributing to the Swelling PressureManuskript (preprint) (Övrigt vetenskapligt)
  • 304.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Bioeconomy.
    Hansson, Per
    Uppsala University, Dep. of Pharmacy, Uppsala Biomedical Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Thermodynamics of the Water-Retaining Properties of Cellulose-Based Networks2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 4, s. 1603-1612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Noncrystalline cellulose-based gel beads were used as a model material to investigate the effect of osmotic stress on a cellulosic network. The gel beads were exposed to osmotic stress by immersion in solutions with different concentrations of high molecular mass dextran and the equilibrium dimensional change of the gel beads was studied using optical microscopy. The volume fraction of cellulose was calculated from the volume of the gel beads in dextran solutions and their dry content and the relation between the cellulose volume fraction and the total osmotic pressure was thus obtained. The results show that the contribution to the osmotic pressure from counterions increases the water-retaining capacity of the beads at high osmotic pressures but also that the main factor controlling the gel bead collapse at high osmotic strains is the resistance to the deformation of the polymer chain network within the beads. Furthermore, the osmotic pressure associated with the deformation of the polymer network, which counteracts the deswelling of the beads, could be fitted to the Wall model indicating that the response of the cellulose polymer networks was independent of the charge of the cellulose. The best fit to the Wall model was obtained when the Flory-Huggins interaction parameter () of the cellulose-water system was set to 0.55-0.60, in agreement with the well-established insolubility of high molecular mass β-(1,4)-d-glucan polymers in water.

  • 305.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Bioeconomy.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Tidigare Institutioner (före 2005), Fiber- och polymerteknologi.
    Elasticity and Ion-Induced Swelling of Cellulose Fibrillar Networks and GelsManuskript (preprint) (Övrigt vetenskapligt)
  • 306.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. RISE Bioecon, Box 5604, S-11486 Stockholm, Sweden.
    Yu, Shun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Pendergraph, Samuel Allen
    RISE Bioecon, Box 5604, S-11486 Stockholm, Sweden..
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hellwig, Johannes
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers2018Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 519, s. 119-129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Macroscopic beads of water-based gels consisting of uncharged and partially charged beta-(1,4)-D-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling.

  • 307.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bengtsson, Stefan
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Hörstedt, Fredrik
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Strategiska hållbarhetsstudier.
    EU:s utsläppshandel otillräckligt för flyget.2018Ingår i: Dagens NyheterArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 308.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bengtsson, Stefan
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Hörstedt, Fredrik
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Strategiska hållbarhetsstudier.
    Hyfs och kunskap krävs i debatten om flyg och klimat.2018Ingår i: Dagens NyheterArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 309.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    KTH måste göra mer för klimatomställningen.2018Ingår i: Dagens NyheterArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 310.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Momcilovic, Dane
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Enebro, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cellulose and cellulose derivatives in biomedical materials: Tools to propose the chemical structure by mass spectrometry2009Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 237Artikel i tidskrift (Övrigt vetenskapligt)
  • 311.
    Kassab, Zineb
    et al.
    Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept MSN, Lot 660 Hay Moulay Rachid, Benguerir 43150, Morocco.;Univ Hassan II Casablanca, Fac Sci Ben Msik, Lab Ingn & Mat LIMAT, BP 7955, Casablanca, Morocco..
    Boujemaoui, Assya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ben Youcef, Hicham
    Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept MSN, Lot 660 Hay Moulay Rachid, Benguerir 43150, Morocco..
    Hajlane, Abdelghani
    Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept MSN, Lot 660 Hay Moulay Rachid, Benguerir 43150, Morocco..
    Hannache, Hassan
    Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept MSN, Lot 660 Hay Moulay Rachid, Benguerir 43150, Morocco.;Univ Hassan II Casablanca, Fac Sci Ben Msik, Lab Ingn & Mat LIMAT, BP 7955, Casablanca, Morocco..
    El Achaby, Mounir
    Mohammed VI Polytech Univ UM6P, Mat Sci & Nanoengn Dept MSN, Lot 660 Hay Moulay Rachid, Benguerir 43150, Morocco..
    Production of cellulose nanofibrils from alfa fibers and its nanoreinforcement potential in polymer nanocomposites2019Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 18, s. 9567-9581Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alfa fibers (Stipa Tenacissima) were effectively utilized in this study as a promising cellulose source for isolation of carboxy-functionalized cellulose nanofibrils (CNFs) using multiple treatments. Pure cellulose microfibers (CMFs) were firstly extracted by alkali and bleaching treatments. CNFs with an average nanofibrils diameter ranging from 1.4 to 4.6 nm and a crystallinity of 89% were isolated from CMFs by a combination of TEMPO-oxidation and mechanical disintegration processes. The morphology and physico-chemical properties of cellulosic materials were evaluated at different stages of treatments using several characterization techniques. Various CNF loadings (5-15 wt%) were incorporated into PVA polymer to evaluate the nanoreinforcement ability of CNFs and to produce CNF-filled PVA nanocomposite materials. The tensile and optical transmittance properties, as well as the morphological and thermal properties of the as-produced CNF-filled PVA nanocomposite films were investigated. It was found that the tensile modulus and strength of nanocomposites were gradually increased with increasing of CNF loadings, with a maximum increase of 90% and 74% was observed for a PVA nanocomposite containing 15 wt% CNFs, respectively. The optical transmittance was reduced from 91% (at 650 nm) for neat PVA polymer to 88%, 82% and 76% for PVA nanocomposites containing 5, 10 and 15 wt% CNFs, respectively. It was also found that the glass transition temperature was gradually increased from 76 degrees C for neat PVA to 89 degrees C for PVA nanocomposite containing 15 wt%. This study demonstrates the importance of Alfa fibers as annual renewable lignocellulosic material to produce CNFs with good morphology and excellent properties. These newly developed carboxy-functionalized CNFs could be considered as a potential nanofiller candidate for the preparation of nanocomposite materials of high transparency and good mechanical properties.Graphic abstract

  • 312.
    Kim, Hyeyun
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Moser, Carl
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Mattinen, Ulriika
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi. Åbo Akademi.
    Henriksson, Gunnar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Cornell, Ann M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Spray-coated nanocellulose based separator/electrode assemblyManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A separator-electrode assembly (SEA) made of wood-based cellulose nanofibers (CNF) and Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) was fabricated by a facile spray-coating process. CNF building blocks were prepared by homogenizing enzymatically pretreated cellulose fibers dispersed in a non-hazardous solvent, 2-propanol (IPA). The porous composite separator was made by spray-coating thin layers CNF-IPA, followed by a PVDF-HFP spray coating, on a lithium ion battery electrode. A CNF substrate was crucial for making a highly porous and thermally stable separator and PVDF-HFP coating enhanced its mechanical stability. The SEA maintained dimensional integrity when subjected to high temperature and when used in lithium ion batteries. A CNF-LiNi1/3Co1/3Mn1/3O2 (NMC) SEA showed excellent electrochemical stability, especially at fast charging/discharging rate, whereas a graphite counterpart showed poor electrochemical performance, resulting in cell failure. A SiO2 layer overcoated on the top of CNF-NMC SEA enabled its application for a proof-of-concept lithium metal battery and for a high energy‐density LiNi0.6Co0.2Mn0.2O2 (NMC622) lithium‐ion battery with excellent electrochemical stability and performances. The utilization of biodegradable materials and non-hazardous solvents such as IPA and acetone makes the development of the CNF based SEA attractive, as an eco-friendly lithium ion battery manufacturing process.

  • 313.
    Kishani, Saina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    On the Solubility of Wood Hemicelluloses in Water and its Influence on the Adsorption at Cellulose/Water Interfaces2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Hemicelluloses are a group of natural polysaccharides and one of the main components of wood. The availability and biodegradability of these polymers have created a great interest in developing new bio-based materials or composites from these materials for different end-use purposes. To develop new materials from these polysaccharides with better functionalities, it is essential to understand the fundamental properties of these compounds. The solubility of hemicelluloses is one of these crucial characteristics since the material has to be dissolved in an appropriate solvent if these biopolymers are to be used in, for example, dense and strong films once the solvents are removed. The interaction of these polysaccharides with different solid surfaces is also significantly influenced by their solubility at the surface/water interface and an understanding of this interaction is essential for describing composite formation, since the polysaccharides are most frequently used together with reinforcing materials such as anisotropic cellulose fibers and fibrils.

    In the work described in this thesis, a novel methodology has been developed for characterizing in detail the solubility of the extracted and model mannans, arabinoxylans and xyloglucan polysaccharides. Different chemical structural analyses, chromatography, light scattering and microscopy techniques have been applied to achieve an accurate understanding of the solubility of the polysaccharides in aqueous media. A careful study has been performed to isolate and purify softwood polysaccharides, followed by the preparation of model samples to investigate the influence of processing, structural substitutions and molar mass on the solubility. Association and the phase separation of hemicelluloses have been identified in aqueous media despite their clear and transparent appearance to the naked eye.

    Natural hemicelluloses are used in combination with cellulose as composite materials both to introduce different functionalities and to utilize the great mechanical properties of cellulose fibrils/fibers. Accordingly, there was a great need to study the influence of the solubility on the interaction and adsorption of these polysaccharides at the cellulose/water interface. The adsorption at the cellulose/water interface was indeed affected by the physicochemical structures and solubility of the polysaccharides, and it has been shown that an increasing molar mass and an increasing polymer concentration lead to formation of associated structures and a phase separation at cellulose model surfaces.

  • 314.
    Kishani, Saina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH.
    Vilaplana, Francisco
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Solubility and adsorption of different xyloglucan fractions to model surfaces2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 315.
    Kittikorn, Thorsak
    et al.
    Prince Songkla Univ, Dept Mat Sci & Technol, Fac Sci, Hat Yai 90112, Thailand..
    Malakul, Raminatun
    Prince Songkla Univ, Dept Microbiol, Fac Sci, Hat Yai 90112, Thailand..
    Strömberg, Emma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Enhancement of mechanical, thermal and antibacterial properties of sisal/polyhydroxybutyrate-co-valerate biodegradable composite2018Ingår i: JOURNAL OF METALS MATERIALS AND MINERALS, ISSN 0857-6149, Vol. 28, nr 1, s. 52-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignocellulosic biocomposite is a promising biodegradable materials, though improvement of the interfacial adhesion between cellulose fibre and polymer matrix is still challenged. Therefore, this work investigated the effect of propionylation of sisal reinforced fibre in the sisal/polyhydroxybutyrate-co-valerate (PHBV) biocomposite. Propionylation involved esterification substitution of propionic anhydride to hydroxyl group of sisal fibre, where ester group (COOR) of propionylated fibre was successfully observed by Fourier transform Infrared spectroscopy (FTIR). Then mechanical and thermal properties were evaluated and biodegradation characteristics were assessed. The tensile strength and modulus of propionylated sisal/PHBV biocomposite were greater than unmodified sisal/PHBV, which revealed better compatibility at the interface. In addition, propionate moieties of sisal fibre could induce crystalline formation of PHBV, as determined by an increase of crystalline phase. The higher decomposition temperature (Td) and activation energy (Ea) of 155 kJ.mol(-1), determined by thermal gravimetric analyser (TGA), were strong confirmation of good thermal resistance of the propionylated sisal biocomposite. The storage modulus, as characterized by dynamic mechanical thermal analyser (DMTA), also revealed the improvement of stiffness. Bacterial growth tests evaluated the inhibition of bacterial growth on the PHBV biocomposites. It was clear that propionylation of sisal fibre decreased colonization of Staphylococcus aureus (SA) and Escherichia coli (E.coli).

  • 316.
    Koemmling, Anja
    et al.
    Bundesanstalt Mat Forsch & Prufung, D-12200 Berlin, Germany..
    Jaunich, Matthias
    Bundesanstalt Mat Forsch & Prufung, D-12200 Berlin, Germany..
    Pourmand, Payam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wolff, Dietmar
    Bundesanstalt Mat Forsch & Prufung, D-12200 Berlin, Germany..
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Analysis of O-Ring Seal Failure under Static Conditions and Determination of End-of-Lifetime Criterion2019Ingår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 11, nr 8, artikel-id 1251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications. Therefore, seal failure of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) O-rings aged in the compressed state at 125 degrees C and at 150 degrees C for up to 1.5 years was analyzed and investigated under static conditions, using both non-lubricated and lubricated seals. Changes of the material properties were analyzed with dynamic-mechanical analysis and permeability experiments. Indenter modulus measurements were used to investigate DLO effects. It became clear that O-rings can remain leak-tight under static conditions even when material properties have already degraded considerably, especially when adhesion effects are encountered. As a feasible and reliable end-of-lifetime criterion for O-ring seals under static conditions should include a safety margin for slight dimensional changes, a modified leakage test involving a small and rapid partial decompression of the seal was introduced that enabled determining a more realistic but still conservative end-of-lifetime criterion for an EPDM seal.

  • 317.
    Koklukaya, Oruc
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Flame-Retardant Cellulose Fibre/Fibril Based Materials via Layer-by-Layer Technique2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    According to an analysis conducted by the Swedish Chemicals Inspectorate in 2006, the approximate numbers of fire injuries per year in Sweden are 100 deaths, 700 major and 700 minor injuries.1 Observations also show that there has been an increase in the number of house fires during recent years. One possible explanation can be the increased use of plastics in the building industry and in furniture. The advantages of easy processing, light weight and low cost make plastic materials most prevalent in the market.  However, plastics behave significantly differently from natural materials in the case of fire. Polymeric materials, including rigid polyurethane foams (PU) which are widely used in the building industry due to their insulating properties, are highly flammable and they release heat at a very high rate. In addition, polymeric materials release more harmful smoke, toxic gases and combustion products than natural materials. A house fire typically starts with the ignition of a combustible material. Flames then spread to nearby materials and shortly thereafter the heat radiation generated reaches a point where the contents of the room suddenly and simultaneously ignite. This stage is called a flash over. After this stage, the fire is fully developed and it continues until everything is consumed. The higher rate of heat and smoke production from plastic materials reduces the time to flash over and hence the time to escape from a fire. The traditional flame-retardant treatments are based mainly on halogenated compounds which are classified as gas phase flame-retardants. The halogenated flame-retardants are under severe investigation due to their adverse effect on health and on the environment since they release toxic gases during combustion and they may leach out and accumulate in the food chain.2-3 The restrictions due to growing environmental concerns have been a driving force to develop alternative flame-retardants by using natural and renewable resources. In recent years, the layer-by-layer (LbL) technique has been used as a simple and versatile surface engineering technique to construct functional nanocoatings through the sequential adsorption of polyelectrolytes and charged nanoparticles in an effort to impart flame-retardant characteristics by inhibiting the combustion cycle.4-5 This thesis presents the physical modification of cellulose fibre/fibril based materials as a means of improving flame-retardant properties.

    In the first part of work described in this thesis, the adsorption of polyelectrolyte multilayers onto pulp fibres was investigated as a way to impart flame-retardant characteristics to paper-based materials. It was found that intumescent nanocoatings consisting of nitrogen and phosphorus containing polyelectrolytes such as chitosan (CH) and poly(vinylphosphonic acid) (PVPA) were able to significantly improve the thermal stability and flame-retardant properties of sheets made of LbL-treated fibres, and were able to self-extinguish the flame in the horizontal flame test (HFT). High magnification images revealed that this improvement in flame-retardancy was due to the formation of a coherent char layer on the fibres (Paper I).6 In addition to imparting flame-retardancy by the LbL-coating of polyethylenimine (PEI) and sodium hexametaphosphate (SHMP), it was also possible to improve the mechanical properties of the paper material with this treatment (Paper III).7

    In the second part of the work, wet-stable porous cellulose fibril-based aerogels were developed by freeze-drying and used as a template for the build-up of intumescent nano-brick wall assemblies. The formation of multilayers of CH, PVPA and montmorillonite clay (MMT) was investigated as a function of solution concentration, and it was found that five quadlayers (QL) of CH/PVPA/CH/MMT treated aerogels using 5 g/L solutions of the respective components were able to self-extinguish the flame in HFT and that they showed no ignition under the heat flux of 35 kW/m2 used in cone calorimetry (Paper II).8 In a different application, a novel low density, porous, wet-stable cellulose fibre network was developed using chemically modified cellulose fibres by solvent exchange from water to acetone followed by drying at room temperature. The fibre networks (FN) were modified using the LbL technique to construct a flame-retardant nanocoating consisting of CH, SHMP, and inorganic particles (i.e., MMT, sepiolite (SEP), and colloidal silica (SNP)). The influence of the shape of the nanoparticles on flame-retardancy was investigated and it was found that plate-like and rod-like clays with a high aspect ratio showed self-extinguishing behaviour in HFT. A 5 QL of CH/SHMP/CH/SEP reduced the peak heat release rate and total smoke release by 47% and 43%, respectively, with an addition of only ~8 wt% to FN (Paper IV).

    Finally, non-crystalline cellulose gel beads were used as a substrate for the LbL assembly of CH and SHMP in model studies aimed at identifying the molecular mechanisms responsible for the fire-retardant properties of the LbL structures. The beads were formed by precipitating the dissolved cellulose-rich fibres according to an earlier described procedure,9 and it was shown that these smooth cellulose beads can be utilized as a model substrate to study the influence of LbL chemistry and nanostructure on flame-retardancy. These new types of model systems thus constitute a new important tool for clarifying the mechanism behind flame-retardant nanocoating systems (Paper V).  

    Publikationen är tillgänglig i fulltext från 2020-12-31 10:00
  • 318.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    López Durán, Vernica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Development of hybrid coatings to reduce flammability of low density cellulose fiber networks via layer-by-layer assemblyManuskript (preprint) (Övrigt vetenskapligt)
  • 319.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Tailoring flame-retardancy and strength of papers via layer-by-layer treatment of cellulose fibers2018Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 4, s. 2691-2709Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The layer-by-layer (LbL) technology was used to adsorb polyelectrolyte multilayers consisting of cationic polyethylenimine (PEI) and anionic sodium hexametaphosphate (SHMP) onto cellulose fibers in order to enhance the flame-retardancy and tensile strength of paper sheets made from these fibers. The fundamental effect of PEI molecular mass on the build-up of the multilayer film was investigated using model cellulose surfaces and a quartz crystal microbalance technique. The adsorption of a low (LMw) and a high molecular weight (HMw) PEI onto cellulose fibers and carboxymethylated (CM) cellulose fibers was investigated using polyelectrolyte titration. The fibers were consecutively treated with PEI and SHMP to deposit 3.5 bilayers (BL) on the fiber surfaces, and the treated fibers were then used to prepare sheets. In addition, a wet-strength paper sheet was prepared and treated with the same LbL coatings. Thermal gravimetric analysis of LbL-treated fibers showed that the onset temperature for cellulose degradation was lowered and that the amount of residue at 800 °C increased. A horizontal flame test and a vertical flame test were used to evaluate the combustion behavior of the paper sheets. Papers prepared from both cellulose fibers and CM-cellulose fibers treated with HMw-PEI/SHMP LbL-combination self-extinguished in a horizontal configuration despite the rather low amounts of adsorbed polymer which form very thin films (wet thickness of ca. 17 nm). The tensile properties of handsheets showed that 3.5 BL of HMw-PEI and SHMP increased the stress at break by 100% compared to sheets prepared from untreated cellulose fibers.

  • 320.
    Koklukaya, Oruc
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Karlsson, Rose-Marie Pernilla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    A study of layer-by-layer nanocoatings on model cellulose gel beads to clarify their flame-retardant characteristicsManuskript (preprint) (Övrigt vetenskapligt)
  • 321.
    Koo, Jun Mo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kang, Jaeryeon
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Shin, Sung-Ho
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jegal, Jonggeon
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Cha, Hyun Gil
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Choy, Seunghwan
    Pohang Univ Sci & Technol POSTECH, Div Integrat Biosci & Biotechnol, Pohang 37673, South Korea..
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Park, Jeyoung
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;Univ Sci & Technol, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Oh, Dongyeop X.
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;Univ Sci & Technol, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Hwang, Sung Yeon
    Korea Res Inst Chem Technol, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;Univ Sci & Technol, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Biobased thermoplastic elastomer with seamless 3D-Printability and superior mechanical properties empowered by in-situ polymerization in the presence of nanocellulose2020Ingår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 185, artikel-id 107885Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A biobased and biocompatible thermoplastic elastomer (TPE) with superior 3D printability was demonstrated with great potential for customized manufacturing technologies and fabrication of biointegrated devices. The inherent structural and stereochemical disadvantages of biobased monomers, such as 2,5-furandicarboxylic acid, in comparison with today used petroleum based monomers like terephthalic acid generally lead to lower mechanical performance for the biobased replacement polymers. This is additionally enhanced by poor interfacial adhesion and fusion commonly encountered during customized manufacturing technologies like 3D printing. Herein, we demonstrate that in-situ polymerization in the presence of trace amounts of cellulose nanocrystals (CNCs) can homogeneously distribute the nanofiller leading to dramatically strengthened thermally 3D-printable bio-furan-based TPE. This TPE exhibited a tensile strength of 67 MPa which is 1.5-7-fold higher than the values reported for silicone and thermoplastic urethane, which are widely used in biomedical applications. In addition, the TPE had an impressive extensibility of 860% and negligible in vivo cytotoxicity; such properties have not been reported to date for bio-based or petrochemical TPEs. While a petrochemical 3D printed TPE counterpart retained only half of the tensile strength compared to the hot-pressed analogue, the 3D-printed biobased TPE insitu modified with nanocellulose maintained 70-80% of its strength under the same experimental conditions. This is explained by inter-diffusion between interfaces facilitated by the nanocellulose and the furan rings. Using the ergonomic shape of a wrist as a 3D-printable design, we successfully manufactured a wearable thermal therapeutic device from the nanocellulose modified biobased TPE, giving promise for wide variety of future applications.

  • 322.
    Koo, Jun Mo
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Kim, Hojun
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Lee, Minkyung
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Park, Seul-A
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jeon, Hyeonyeol
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Shin, Sung-Ho
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Kim, Seon-Mi
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Cha, Hyun Gil
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jegal, Jonggeon
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Kim, Byeong-Su
    Yonsei Univ, Dept Chem, Seoul 03722, South Korea..
    Choi, Bong Gill
    Kangwon Natl Univ, Dept Chem Engn, Samcheok 25913, Gangwon Do, South Korea..
    Hwang, Sung Yeon
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Oh, Dongyeop X.
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Park, Jeyoung
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Nonstop Monomer-to-Aramid Nanofiber Synthesis with Remarkable Reinforcement Ability2019Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, nr 3, s. 923-934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aramid nanofibers (ANFs), typically produced by exfoliating aramid microfibers (Kevlar) in alkaline media, exhibit excellent mechanical properties and have therefore attracted increased attention as nanoscale building blocks. However, the preparation of aramid microfibers involves laborious and hazardous processes, which limits the industrial-scale use of ANFs. This work describes a facile and direct monomer-to-ANF synthesis via an as-synthesized intermediate low-molecular-weight poly(p-phenylene terephthalamide) (PPTA) without requiring the environmentally destructive acids and high-order shearing processes. Under the employed conditions, PPTA immediately dissociates and self-assembles into ANFs within a time period of 15 h, which is much shorter than the time of 180 h (not including the Kevlar preparation time) required for the Kevlar-to-ANF conversion. Interestingly, the fabricated ANFs exhibit nanoscale dimensions and thermoplastic polyurethane (TPU) reinforcing effects similar to those of Kevlar-derived ANFs; i.e., a 1.5-fold TPU toughness improvement and a maximum ultimate tensile strength of 84 MPa are achieved at an ANF content of only 0.04 wt %. Remarkable reinforcement ability investigated by comprehensive analytical data comes from ANFs, which disturb ordered hydrogen bonding in hard segments and induce strain hardening along the elongation pathway. Thus, the developed approach paves the way to industrial-scale production of ANFs and related nanocomposites.

  • 323.
    Koskela, Salla
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Wang, Shennan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Yang, Xuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Li, Kai
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Srivastava, Vaibhav
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    McKee, Lauren S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bulone, Vincent
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Enzyme-assisted preparation of nanocellulose from wood holocellulose fibers2019Övrigt (Övrigt vetenskapligt)
  • 324.
    Kousal, Jaroslav
    et al.
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Shelemin, Artem
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Schwartzkopf, Matthias
    Deutsches Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Polonskyi, Oleksandr
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Hanus, Jan
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Solar, Pavel
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Vaidulych, Mykhailo
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Nikitin, Daniil
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Pleskunov, Pavel
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Krtous, Zdenek
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Strunskus, Thomas
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Faupel, Franz
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Deutsches Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Biederman, Hynek
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Choukourov, Andrei
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Magnetron-sputtered copper nanoparticles: lost in gas aggregation and found by in situ X-ray scattering2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 38, s. 18275-18281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magnetron discharge in a cold buffer gas represents a liquid-free approach to the synthesis of metal nanoparticles (NPs) with tailored structure, chemical composition and size. Despite a large number of metal NPs that were successfully produced by this method, the knowledge of the mechanisms of their nucleation and growth in the discharge is still limited, mainly because of the lack of in situ experimental data. In this work, we present the results of in situ Small Angle X-ray Scattering measurements performed in the vicinity of a Cu magnetron target with Ar used as a buffer gas. Condensation of atomic metal vapours is found to occur mainly at several mm distance from the target plane. The NPs are found to be captured preferentially within a region circumscribed by the magnetron plasma ring. In this capture zone, the NPs grow to the size of 90 nm whereas smaller ones sized 10-20 nm may escape and constitute a NP beam. Time-resolved measurements of the discharge indicate that the electrostatic force acting on the charged NPs may be largely responsible for their capturing nearby the magnetron.

  • 325.
    Kubyshkina, Elena
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Unge, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material. ABB Corporate Research.
    Impact of interfacial structure on charge dynamics in nanocomposite dielectricsManuskript (preprint) (Övrigt vetenskapligt)
  • 326.
    Kubyshkina, Elena
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    Unge, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material. ABB Corporate Research, Västerås, SE 72178, Sweden.
    Impact of interfacial structure on the charge dynamics in nanocomposite dielectrics2019Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, nr 4, artikel-id 045109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate that the chemistry at the interface between nanoparticle and polymer matrix influence charge dynamics in polymer nanocomposite. Applying density functional theory, we investigate the influence of crystal surface termination, silicon treatment, and water and carboxyl defect on the electronic properties of interfaces in MgO-polyethylene nanocomposite. The band offsets between the nanofiller and base matrix materials show a strong dependence on the chemical composition at the interface. Based on the calculated electronic structure, we propose a band alignment model for charge dynamics in nanocomposite dielectrics. The model not only provides a mechanism of reduction of space charge and conductivity but also predicts an increase in thermal stress and susceptibility to the chemical additives. It is suggested that the suppression mechanisms of space charge and conductivity in nanocomposites can be inherently unstable and promote material aging. The results of the study show a need for long-term performance tests of nanocomposite dielectrics.

  • 327.
    Kupka, Vojtech
    et al.
    Brno Univ Technol, CEITEC Cent European Inst Technol, Brno 61200, Czech Republic..
    Zhou, Qi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ansari, Farhan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Tang, Hu
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Royal Inst Technol KTH, AlbaNova Univ Ctr, Sch Biotechnol, S-10691 Stockholm, Sweden..
    Slouf, Miroslav
    Acad Sci Czech Republ, Inst Macromol Chem, CR-16206 Prague, Czech Republic..
    Vojtova, Lucy
    Brno Univ Technol, CEITEC Cent European Inst Technol, Brno 61200, Czech Republic.;SCITEG As, U Vodarny 2965-2, Brno 61600, Czech Republic..
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Jancar, Josef
    Brno Univ Technol, CEITEC Cent European Inst Technol, Brno 61200, Czech Republic.;SCITEG As, U Vodarny 2965-2, Brno 61600, Czech Republic..
    Well-dispersed polyurethane/cellulose nanocrystal nanocomposites synthesized by a solvent-free procedure in bulk2019Ingår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 40, s. E456-E465Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyurethane (PU) nanocomposites utilizing cellulose nanocrystals (CNCs) as nanofiller and amorphous PU matrix were synthesized in a novel solvent-free bulk process. A green nanofiller, CNCs, was studied as reinforcement and was further modified by grafting poly(ethylene glycol) (PEG) on the CNC surface (CNC-PEG). Transmission electron microscopy revealed an excellent dispersion of the PEGylated CNC nanoparticles in the PU matrix, whereas as-received CNCs formed agglomerates. The results indicated strong improvements in tensile properties with Young's modulus increasing up to 50% and strength up to 25% for both, PU/CNC and PU/CNC-PEG nanocomposites. The enhanced tensile modulus was attributed to stiff particle reinforcement together with an increase in glass transition temperature.

  • 328.
    Köklükaya, Oruç
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, F.
    López Durán, Veronica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Layer-by-layer modified low density cellulose fiber networks: A sustainable and fireproof alternative to petroleum based foams2020Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 230, artikel-id 115616Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood-based cellulose fibers were used to prepare porous, low density and wet-stable fiber networks (FN). Multilayer coatings consisting of chitosan (CH), sodium hexametaphosphate (SHMP) and inorganic nanoparticles comprising of either sodium montmorillonite (MMT), sepiolite (SEP) or colloidal silica (SNP) were deposited by the layer-by-layer (LbL) technique onto FNs in an effort to impart flame-retardancy. A simulated fire scenario measured by cone calorimetry showed that five quadlayers (QL) of CH/SHMP/CH/MMT, CH/SHMP/CH/SEP and CH/SHMP/CH/SNP can produce significant reduction in peak heat release rate (pkHRR). In detail, the coating containing SEP showed the largest reduction of the pkHRR by 47% relative to the uncoated FN. MMT and SEP coated FNs were also able to self-extinguish fire and to retain their shapes after direct exposure to a methane flame. This study hence shows that the LbL assembly is a highly effective way to impart flame-retardant properties to this new type of porous FN.

  • 329.
    Kürten, Charlotte
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    On Catalytic Mechanisms for Rational Enzyme Design Strategies2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Enzymes enable life by promoting chemical reactions that govern the metabolism of all living organisms. As green catalysts, they have been extensively used in industry. However, to reach their full potential, engineering is often required, which can benefit from a detailed understanding of the underlying reaction mechanism.

    In Paper I, we screened for an esterase with promiscuous amidase activity capitalizing on a key hydrogen bond acceptor that is able to stabilize the rate limiting nitrogen inversion. In silicoanalyses revealed the esterase patatin as promising target that indeed catalyzed amide hydrolysis when tested in vitro. While key transition state stabilizers for amide hydrolysis are known, we were interested in increasing our fundamental understanding of terpene cyclase catalysis (Paper II-V). In Paper II, kinetic studies in D2O-enriched buffers using a soluble diterpene cyclase suggested that hydrogen tunneling is part of the rate-limiting protonation step. In Paper III, we performed intense computational analyses on a bacterial triterpene cyclase to show the influence of water flow on catalysis. Water movement in the active site and in specific water channels, influencing transition state formation, was detected using streamline analysis. In Paper IV and V, we focused on the human membrane-bound triterpene cyclase oxidosqualene cyclase. We first established a bacterial expression and purification protocol in Paper IV, before performing detailed in vitroand in silicoanalyses in Paper V. Our analyses showed an entropy-driven reaction mechanism and the existence of a tunnel network in the structure of the human enzyme. The influence of water network rearrangements on the thermodynamics of the transition state formation were confirmed. Introducing mutations in the tunnel lining residues severely affected the temperature dependence of the reaction by changing the water flow and network rearrangements in the tunnels and concomitant the active site.

    Ladda ner fulltext (pdf)
    On Catalytic Mechanisms for Rational Enzyme Design Strategies
  • 330.
    Kürten, Charlotte
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Eriksson, Adam
    Maddalo, Gianluca
    Edfors, Fredrik
    Uhlén, Mathias
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Syrén, Per-Olof
    KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Engineering of water networks in class II terpene cyclases underscores the importance of amino acid hydration and entropy in biocatalysis and enzyme designManuskript (preprint) (Övrigt vetenskapligt)
  • 331. Lang, A. W.
    et al.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    De Keersmaecker, M.
    Shen, D. E.
    Österholm, A.M.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Reynolds, J. R.
    Transparent Wood Smart Windows: Polymer Electrochromic Devices Based on Poly(3,4-Ethylenedioxythiophene):Poly(Styrene Sulfonate) Electrodes2018Ingår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, nr 5, s. 854-863Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood composites, with their high strength and toughness, thermal insulation, and excellent transmissivity, offer a route to replace glass for diffusely transmitting windows. Here, conjugated-polymer-based electrochromic devices (ECDs) that switch on-demand are demonstrated using transparent wood coated with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a transparent conducting electrode. These ECDs exhibit a vibrant magenta-to-clear color change that results from a remarkably colorless bleached state. Furthermore, they require low energy and power inputs of 3 mWh m−2 at 2 W m−2 to switch due to a high coloration efficiency (590 cm2 C−1) and low driving voltage (0.8 V). Each device component is processed with high-throughput methods, which highlights the opportunity to apply this approach to fabricate mechanically robust, energy-efficient smart windows on a large scale. 

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    cssc.201702026
  • 332.
    Lange, Heiko
    et al.
    Univ Roma Tor Vergata, Dept Chem Sci & Technol, Rome, Italy..
    Sevastyanova, Olena
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Crestini, Claudia
    Univ Roma Tor Vergata, Dept Chem Sci & Technol, Rome, Italy..
    Correlating structural features of lignin with physical properties: Toward a descriptive-predictive database2015Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Artikel i tidskrift (Övrigt vetenskapligt)
  • 333.
    Larsen, Bjarke Strom
    et al.
    Univ Copenhagen, Dept Pharm, Copenhagen, Denmark. kytte, Jeppe.
    Skytte, Jeppe
    Svagan, Anna J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Meng-Lund, Helena
    Grohganz, Holger
    Löbmann, Korbinian
    Using dextran of different molecular weights to achieve faster eeze-drying and improved storage stability of lactate dehydrogenase2019Ingår i: Pharmaceutical development and technology (Print), ISSN 1083-7450, E-ISSN 1097-9867, Vol. 24, nr 3, s. 323-328Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Freeze-drying of protein formulations is frequently used to maintain otein activity during storage. The freeze-drying process usually quires long primary drying times because the highest acceptable drying mperature to obtain acceptable products is dependent on the glass ansition temperature of the maximally freeze-concentrated solution -g). On the other hand, retaining protein activity during storage is lated to the glass transition temperature (T-g) of the final eeze-dried product. In this study, dextrans with different molecular ight (1 and 40kDa) and mixtures thereof at the ratio 3:1, 1:1, and 1:3 /w) were used as cryo-/lyoprotectant and their impact on the stability the model protein lactate dehydrogenase (LDH) was investigated at evated temperatures (40 degrees C and 60 degrees C). The dextran rmulations were then compared to formulations containing sucrose as yo-/lyoprotectant. Because of the higher T-g values of the dextrans, e primary drying times could be reduced compared to freeze-drying with crose. Similarly, the higher T-g and T-g of dextrans relative to crose led to benefits during storage which was shown through improved otection of LDH activity.

  • 334.
    Larsson, Per
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Chemical modification of cellulose fibres and nanofibrils for an expanded material property space and novel applications2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 335.
    Larsson, Per A.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Linvill, Eric
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.). KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Lo Re, Giada
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Östlund, Sören
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.). KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ductile and thermoplastic cellulose with novel application and design opportunities2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 336.
    Larsson, Per A.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Riazanova, Anastasiia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ciftci, Goksu Cinar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Rojas, Ramiro
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ovrebo, Hans Henrik
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Towards optimised size distribution in commercial microfibrillated cellulose: a fractionation approach2019Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 3, s. 1565-1575Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the successful commercialisation of microfibrillated cellulose (MFC) it is of utmost importance to carefully characterise the constituent cellulose particles. This could for instance lead to the development of MFC grades with size distributions tailored for specific applications. Characterization of MFC is challenging due to the heterogeneous chemical and structural nature of MFC. This study describes a fractionation approach that combines two steps of physical sieving of larger particles and a final centrifugation step to separate out the smallest, colloidally stable particles, resulting in four distinctly different size fractions. The properties, such as size and charge, of each fraction were studied, as well as MFC filtration time, film formation, and film properties (mechanical and optical). It was found that virtually all surface charges, determined by polyelectrolyte adsorption, are located in the colloidally stable fraction of the MFC. In addition, the amount of available surface charges can be used as an estimate of the degree of fibrillation of the MFC. The partly fibrillated particles frequently displayed a branching, fringed morphology. Mechanical testing of films from the different fractions revealed that the removal of large particles may be more important for strength than achieving full fibrillation. Overall, this study demonstrates that by controlling the size distribution in MFC grades, property profiles including dewatering time to make films by filtration, rheology, film strength and optical transmittance could be optimised. [GRAPHICS] .

  • 337.
    Larsson, Per Tomas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. Innventia AB, Stockholm, Sweden..
    Karlsson, Pernilla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Swelling behavior of cellulose rich materials in water2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 338.
    Larsson, Per Tomas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. RISE Innventia AB, Stockholm, Sweden..
    Karlsson, Pernilla
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH Fibre Polymer Techn, Stockholm, Sweden..
    Why haven't plastic packaging been replaced by cellulose?2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 339.
    Lee, Ching-Hwa
    et al.
    Da Yeh Univ, Dept Environm Engn, Changhua 51591, Taiwan..
    Terbish, Narangarav
    Da Yeh Univ, Dept Environm Engn, Changhua 51591, Taiwan..
    Holder, Shima L.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material. Da Yeh Univ, Dept Environm Engn, Changhua 51591, Taiwan.
    Popuri, Srinivasa R.
    Univ West Indies, Dept Biol & Chem Sci, Cave Hill Campus, Wanstead, Barbados..
    Nalluri, Lakshmi P.
    Da Yeh Univ, Dept Environm Engn, Changhua 51591, Taiwan..
    A study on development of alternative biopolymers based proton exchange membrane for microbial fuel cells and effect of blending ratio and ionic crosslinking on bioenergy generation and COD removal2019Ingår i: Journal of polymer research, ISSN 1022-9760, E-ISSN 1572-8935, Vol. 26, nr 12, artikel-id 285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of biopolymers as alternative proton exchange membranes (PEMs) is receiving significant attention in microbial fuel cells (MFCs) due to their attractive and competitive physico-chemical properties, eco-friendly behavior and biodegradable nature. In this study we developed the biopolymer-based blend PEMs using chitosan (Cs) alginate (Alg) for bioelectricity production and simultaneous wastewater treatment and also investigated the effect of blending ratio of the membrane and ionic crosslinking between the two biopolymers on MFC performance. The membranes of Cs:Alg were fabricated in volume ratio of 100:0, 80:20, 60:40, 50:50, 40:60, 20:80, and 0:100 via a solution casting and solvent evaporation method followed by crosslinking with phosphoric acid to avoid excess swelling of the hydrophilic polymers and increase the mechanical strength. Among these, the 50:50 ratio membranes exhibited the highest power generation (115 mW/m(2)) with 1340% water uptake, however the membrane with 40:60 ratio displayed maximum COD removal (78.6%) compared to other membranes. The structure and surface morphology of obtained membranes were examined using Infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), Sorption and cation exchange capacity, and tensile strength. Sorption, cation exchange capacity and mechanical properties of Cs membranes increased with the addition of Alg with near to stoichiometric ratio.

  • 340.
    Li, Gen
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Dobryden, Illia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Salazar-Sandoval, Eric Johansson
    RISE Res Inst Sweden, Div Biosci & Mat, Box 5607, SE-11486 Stockholm, Sweden..
    Johansson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Claesson, Per M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. RISE Res Inst Sweden, Div Biosci & Mat, Box 5607, SE-11486 Stockholm, Sweden..
    Load-dependent surface nanomechanical properties of poly-HEMA hydrogels in aqueous medium2019Ingår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, nr 38, s. 7704-7714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical properties of hydrogels are of importance in many applications, including scaffolds and drug delivery vehicles where the release of drugs is controlled by water transport. While the macroscopic mechanical properties of hydrogels have been reported frequently, there are less studies devoted to the equally important nanomechanical response to local load and shear. Scanning probe methods offer the possibility to gain insight on surface nanomechanical properties with high spatial resolution, and thereby provide fundamental insights on local material property variations. In this work, we investigate the local response to load and shear of poly(2-hydroxyethyl methacrylate) hydrogels with two different cross-linking densities submerged in aqueous solution. The response of the hydrogels to purely normal loads, as well as the combined action of load and shear, was found to be complex due to viscoelastic effects. Our results show that the surface stiffness of the hydrogel samples increased with increasing load, while the tip-hydrogel adhesion was strongly affected by the load only when the cross-linking density was low. The combined action of load and shear results in the formation of a temporary sub-micrometer hill in front of the laterally moving tip. As the tip pushes against such hills, a pronounced stick-slip effect is observed for the hydrogel with low cross-linking density. No plastic deformation or permanent wear scar was found under our experimental conditions.

  • 341.
    Li, Hailong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH Royal Inst Technol, Fibre Technol, Stockholm, Sweden..
    Internal structural evolution of regenerated cellulose beads during drying2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 342.
    Li, Nian
    et al.
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Song, Lin
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Biessmann, Lorenz
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Xia, Senlin
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Ohm, Wiebke
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Brett, Calvin
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik.
    Hadjixenophontos, Efi
    Univ Stuttgart, Inst Mat Sci, Heisenbergstr 3, D-70569 Stuttgart, Germany..
    Schmitz, Guido
    Univ Stuttgart, Inst Mat Sci, Heisenbergstr 3, D-70569 Stuttgart, Germany..
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85748 Garching, Germany..
    Morphology Phase Diagram of Slot-Die Printed TiO2 Films Based on Sol-Gel Synthesis2019Ingår i: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, nr 12, artikel-id 1900558Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mesoporous titania films with tailored nanostructures are fabricated via slot-die printing, which is a simple and cost-effective thin-film deposition technique with the possibility of a large-scale manufacturing. Based on this technique, which is favorable in industry, TiO2 films possess the similar advantage with polymer semiconducting devices like ease of large-scale production. The titania morphologies, including foam-like nanostructures, nanowire aggregates, collapsed vesicles and nanogranules, are achieved via a so-called block-copolymer-assisted sol-gel synthesis. By adjusting the weight fraction of reactants, the ternary morphology phase diagram of the printed titania films is probed after template removal. The surface and inner morphology evolutions are explored with scanning electron microscopy and grazing incidence small-angle X-ray scattering, respectively. Special focus is set on foam-like titania nanostructures as they are of especial interest for, e.g., solar cell applications. At a low weight fraction of the titania precursor titanium(IV)isopropoxide (TTIP), foam-like titania films are achieved, which exhibit a high uniformity and possess large pore sizes. The anatase phase of the highly crystalline titania films is verified with X-ray diffraction and transmission electron microscopy.

  • 343.
    Li, Yuanyuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Cheng, Ming
    Jungstedt, Erik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Xu, Bo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Optically Transparent Wood Substrate for Perovskite Solar Cells2019Ingår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, nr 6, s. 6061-6067Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood is a candidate for use as an energy-saving building material due to its low density (ca. 1.2 g/cm(3)), high optical transmittance (over 85% at 1 mm thickness), low thermal conductivity (0.23 W m(-1) K-1), and good load-bearing performance with tough failure behavior (no shattering). High optical transmittance also makes transparent wood a candidate for optoelectronic devices. In this work, for the first time, perovskite solar cells processed at low temperature (<150 degrees C) were successfully assembled directly on transparent wood substrates. A power conversion efficiency up to 16.8% was obtained. The technologies demonstrated may pave the way for integration of solar cells with light transmitting wood building structures for energy-saving purposes.

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    fulltext
  • 344.
    Li, Yuanyuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Vasileva, Elena
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Sychugov, Ilya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Optically Transparent Wood: Recent Progress, Opportunities, and Challenges2018Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, nr 14, artikel-id 1800059Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Transparent wood is an emerging load-bearing material reinvented from natural wood scaffolds with added light management functionalities. Such material shows promising properties for buildings and related structural applications, including its renewable and abundant origin, interesting optical properties, outstanding mechanical performance, low density, low thermal conductivity, and great potential for multifunctionalization. In this study, a detailed summary of recent progress on the transparent wood research topic is presented. Remaining questions and challenges related to transparent wood preparation, optical property measurements, and transparent wood modification and applications are discussed.

    Ladda ner fulltext (pdf)
    fulltext
  • 345.
    Li, Yuanyuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Yang, Xuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Fu, Qiliang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Rojas, Ramiro
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Yan, Max
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Berglund, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Towards centimeter thick transparent wood through interface manipulation2018Ingår i: International Journal of Materials and Chemistry, ISSN 2166-5346, E-ISSN 2166-5354, Vol. 6, s. 1094-1101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood is an attractive structural material for energy-saving buildings due to its high optical transmittance, good thermal insulation, and high toughness. However, thick highly transparent wood is challenging to realize. In the current work, highly transparent wood (1.5 mm) with a transmittance of 92%, close to that of pure PMMA (95%), is demonstrated. The high transmittance was realized by interface manipulation through acetylation of wood template. Both experiments and electromagnetic modeling support that the improved transmittance is mainly due to elimination of interface debonding gap. By applying this method, a centimeter-thick transparent wood structure was obtained. The transparent wood could be used as a substrate for an optically tunable window by laminating a polymer dispersed liquid crystal (PDLC) film on top. The techniques demonstrated are a step towards the replacement of glass in smart windows and smart buildings.

    Ladda ner fulltext (pdf)
    fulltext
  • 346.
    Limaye, Mukta, V
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden.;Royal Inst Thchnol, Wallenberg Wood Sci Ctr, SE-10044 Stockholm, Sweden.;Indian Inst Sci Educ & Res, Dept Phys, Berhampur 760010, Odisha, India..
    Schutz, Christina
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden.;Royal Inst Thchnol, Wallenberg Wood Sci Ctr, SE-10044 Stockholm, Sweden..
    Kriechbaum, Konstantin
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Wohlert, Jakob
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Bacsik, Zoltan
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Wohlert, Malin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Xia, Wei
    Angstrom Lab, Dept Engn Sci Appl Mat Sci, SE-75121 Uppsala, Sweden..
    Plea, Mama
    Univ Sci Tech & Technol Bamako, Lab Phys Chim Mat, BP E 2306, Bamako, Mali..
    Dembele, Cheick
    Univ Sci Tech & Technol Bamako, Lab Phys Chim Mat, BP E 2306, Bamako, Mali..
    Salazar-Alvarez, German
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden.;Royal Inst Thchnol, Wallenberg Wood Sci Ctr, SE-10044 Stockholm, Sweden..
    Bergström, Lennart
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Functionalization and patterning of nanocellulose films by surface-bound nanoparticles of hydrolyzable tannins and multivalent metal ions2019Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, nr 41, s. 19278-19284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inspired by the Bogolanfini dyeing technique, we report how flexible nanofibrillated cellulose (CNF) films can be functionalized and patterned by surface-bound nanoparticles of hydrolyzable tannins and multivalent metal ions with tunable colors. Molecular dynamics simulations show that gallic acid (GA) and ellagic acid (EA) rapidly adsorb and assemble on the CNF surface, and atomic force microscopy confirms that nanosized GA assemblies cover the surface of the CNF. CNF films were patterned with tannin-metal ion nanoparticles by an in-fibre reaction between the pre-impregnated tannin and the metal ions in the printing ink. Spectroscopic studies show that the Fe-III/II ions interact with GA and form surface-bound, stable GA-Fe-III/II nanoparticles. The functionalization and patterning of CNF films with metal ion-hydrolyzable tannin nanoparticles is a versatile route to functionalize films based on renewable materials and of interest for biomedical and environmental applications.

  • 347.
    Lindblad, Margaretha Soderqvist
    et al.
    Sodra Cell AB, R&D, S-43024 Varobacka, Sweden..
    Albertsson, Ann-Christine
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Dahlman, Olof
    STFI Packforsk AB, SE-10044 Stockholm, Sweden..
    Sjogren, John
    PRV, S-10242 Stockholm, Sweden..
    CELL 92-Modified galactoglucomannan from forestry wastewater utilized for oxygen barrier films and hydrogels2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 233, s. 799-799Artikel i tidskrift (Övrigt vetenskapligt)
  • 348.
    Lindén, Pär A.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Stabilising mannose using sodium dithionite at alkaline conditions2020Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 74, nr 2, s. 131-140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The kraft process remains the dominant-chemical pulping process but still struggles with extensive hemicellulose degradation. Such degradation has previously been mitigated through the use of anthraquinone; but due to it recently being found to have carcinogenic properties, anthraquinone is now being phased out. One alternative, sodium dithionite, was initially investigated in the 1950s but was found to be unviable. The present study investigated whether sodium dithionite could be made viable through the use of different processing parameters, using mannose as a model compound and measuring the yield of mannitol in the various systems using gas chromatography with flame ionization detection (GC-FID) and nuclear magnetic resonance (NMR). Alkalinity was found to be crucial; at pH 14 as well as pH 7, dithionite indeed proved unviable, but if pH was kept at either 8 or 10 significant reduction was seen to occur. The best results were obtained at pH 10 when a lower temperature (70 degrees C) was used to compensate for alkaline degradation of the mannose reactant.

  • 349.
    Liu, Hailong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Teknisk mekanik, Farkostteknik och Solidmekanik, Hållfasthetslära.
    Ahlinder, Astrid
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Yassin, M. A.
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Gasser, T. Christian
    KTH, Skolan för teknikvetenskap (SCI), Teknisk mekanik, Farkostteknik och Solidmekanik, Hållfasthetslära.
    Computational and experimental characterization of 3D-printed PCL structures toward the design of soft biological tissue scaffolds2020Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 188, artikel-id 108488Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Degradable porous polymeric structures are attractive candidates for biological tissue scaffolds, and adequate mechanical, transport, chemical and biological properties determine their functionality. Aside from the properties of polymer-based materials, the scaffold's meso-structure controls its elasticity at the organ length-scale. This study investigated the effect of the meso-structure on scaffolds' mechanical and transport properties using finite element analysis (FEA) and computational fluid dynamics (CFD). A number of poly (ε-caprolactone) (PCL) - based scaffolds were 3D printed, analyzed by microcomputed tomography (micro-CT) and mechanically tested. We found that the gradient (G) and gradient and staggered (GS) meso-structure designs led to a higher scaffold permeability, a more homogeneous flow inside the scaffold, and a lower wall shear stress (WSS) in comparison with the basic (B) meso-structure design. The GS design resulted in scaffold stiffness as low as 1.07/0.97 MPa under compression/tension, figures that are comparative with several soft tissues. Image processing of micro-CT data demonstrated that the imposed meso-structures could have been adequately realized through 3D printing, and experimental testing validated FEA analysis. Our results suggest that the properties of 3D-printed PCL-based scaffolds can be tuned via meso-structures toward soft tissue engineering applications. The biological function of designed scaffolds should be further explored in-situ studies.

  • 350.
    Lo Re, Giada
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Engström, Joakim
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wu, Qiong
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Gedde, Ulf W.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Olsson, Richard
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Improved Cellulose Nanofibril Dispersion in Melt-Processed Polycaprolactone Nanocomposites by a Latex-Mediated Interphase and Wet Feeding as LDPE Alternative2018Ingår i: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, nr 6, s. 2669-2677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work reports the development of a sustainable and green one-step wet-feeding method to prepare tougher and stronger nanocomposites from biodegradable cellulose nanofibrils (CNF)/polycaprolactone (PCL) constituents, compatibilized with reversible addition fragmentation chain transfer-mediated surfactant-free poly(methyl methacrylate) (PMMA) latex nanoparticles. When a PMMA latex is used, a favorable electrostatic interaction between CNF and the latex is obtained, which facilitates mixing of the constituents and hinders CNF agglomeration. The improved dispersion is manifested in significant improvement of mechanical properties compared with the reference material. The tensile tests show much higher modulus (620 MPa) and strength (23 MPa) at 10 wt % CNF content (compared to the neat PCL reference modulus of 240 and 16 MPa strength), while maintaining high level of work to fracture the matrix (7 times higher than the reference nanocomposite without the latex compatibilizer). Rheological analysis showed a strongly increased viscosity as the PMMA latex was added, that is, from a well-dispersed and strongly interacting CNF network in the PCL.

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