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  • 1.
    Ansari, Farhan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Galland, Sylvain
    Fernberg, P.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Stiff and ductile nanocomposites of epoxy reinforced with cellulose nanofibrils2013In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2013, p. 5575-5582Conference paper (Refereed)
  • 2.
    Ansari, Farhan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Sjöstedt, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Larsson, Per Tomas
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Hierarchical wood cellulose fiber/epoxy biocomposites: Materials design of fiber porosity and nanostructure2015In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 74, p. 60-68Article in journal (Refereed)
    Abstract [en]

    Delignified chemical wood pulp fibers can be designed to have a controlled structure of cellulose fibril aggregates to serve as porous templates in biocomposites with unique properties. The potential of these fibers as reinforcement for an epoxy matrix (EP) was investigated in this work. Networks of porous wood fibers were impregnated with monomeric epoxy and cured. Microscopy images from ultramicrotomed cross sections and tensile fractured surfaces were used to study the distribution of matrix inside and around the fibers - at two different length scales. Mechanical characterization at different relative humidity showed much improved mechanical properties of biocomposites based on epoxy-impregnated fibers and they were rather insensitive to surrounding humidity. Furthermore, the mechanical properties of cellulose-fiber biocomposites were compared with those of cellulose-nanofibril (CNF) composites; strong similarities were found between the two materials. The reasons for this, some limitations and the role of specific surface area of the fiber are discussed.

  • 3.
    Banerjee, Indradumna
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Salih, Tagrid
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Ramachandraiah, Harisha
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Erlandsson, Johan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, Superseded Departments (pre-2005), Chemistry.
    Araújo, A. C.
    Karlsson, M.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Slipdisc: A versatile sample preparation platform for point of care diagnostics2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 56, p. 35048-35054Article in journal (Refereed)
    Abstract [en]

    We report a microfluidic sample preparation platform called "Slipdisc" based on slipchip technology. Slipdisc is a rotational slipchip that uses a unique hand-wound clockwork mechanism for precise movement of specially fabricated polycarbonate discs. In operation, the microchannels and microchambers carved on the closely aligned microfluidic discs convert from continuous filled paths to defined compartments using the slip movement. The clockwork mechanism introduced here is characterised by a food dye experiment and a conventional HRP TMB reaction before measuring lactate dehydrogenase (LDH) enzyme levels, which is a crucial biomarker for neonatal diagnostics. The colorimetry based detection of LDH was performed with an unmodified camera and an image analysis procedure based on normalising images and observing changes in red channel intensity. The analysis showed a close to unity coefficient of determination (R2 = 0.96) in detecting the LDH concentration when compared with a standard Chemical Analyser, demonstrating the excellent performance of the slipdisc platform with colorimetric detection. The versatile point of care sample preparation platform should ideally be suited for a multitude of applications at resource-limited settings.

  • 4.
    Bergström, Elina Mabasa
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Salmen, Lennart
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Joby Kochumalayil, Jose
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Plasticized xyloglucan for improved toughness-Thermal and mechanical behaviour2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, no 4, p. 2532-2537Article in journal (Refereed)
    Abstract [en]

    Tamarind seed xyloglucan is an interesting polysaccharide of high molar mass with excellent thermomechanical properties. Several plasticizers were studied in order to facilitate thermal processing and improve toughness (work to fracture) of xyloglucan film materials: sorbitol, urea, glycerol and polyethylene oxide. Films of different compositions were cast and studied by thermogravimetric analysis (TGA), calorimetry (DSC), dynamic mechanical thermal analysis (DMA) and tensile tests. Results are analysed and discussed based on mechanisms and practical considerations. Highly favourable characteristics were found with XG/sorbitol combinations, and the thermomechanical properties motivate further work on this material system, for instance as a matrix in biocomposite materials.

  • 5.
    Borodulina, Svetlana
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Kulachenko, Artem
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Galland, Sylvain
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Stress-strain curve of paper revisited2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 318-328Article in journal (Refereed)
    Abstract [en]

    We have investigated a relation between micromechanical processes and the stress-strain curve of a dry fiber network during tensile loading. By using a detailed particle-level simulation tool we investigate, among other things, the impact of "non-traditional" bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds. This is probably the first three-dimensional model which is capable of simulating the fracture process of paper accounting for nonlinearities at the fiber level and bond failures. The failure behavior of the network considered in the study could be changed significantly by relatively small changes in bond strength, as compared to the scatter in bonding data found in the literature. We have identified that compliance of the bonding regions has a significant impact on network strength. By comparing networks with weak and strong bonds, we concluded that large local strains are the precursors of bond failures and not the other way around.

  • 6.
    Bruce, Carl
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Surface Modification of Cellulose by Covalent Grafting and Physical Adsorption for Biocomposite Applications2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is an increasing interest to replace fossil-based materials with renewable alternatives. Cellulose fibers/nanofibrils (CNF) are sustainable options since they are biobased and biodegradable. In addition, they combine low weight with high strength; making them suitable to, for example, reinforce composites. However, to be able to use them as such, modifications are often necessary. This study therefore aimed at modifying cellulose fibers, model surfaces of cellulose and CNF. Cellulose fibers and CNF were thereafter incorporated into composite materials and evaluated.

    Surface-initiated ring-opening polymerization (SI-ROP) was performed to graft ε-caprolactone (ε-CL) from cellulose fibers. From these fibers, paper-sheet biocomposites were produced that could form laminate structures without the need for any addition of matrix polymer.

    By combining ROP and atom transfer radical polymerization (ATRP), diblock copolymers of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and PCL were prepared. Quaternized (cationic) PDMAEMA, allowed physical adsorption of block copolymers onto anionic surfaces, and, thereby, alteration of surface energy and adhesion to a potential matrix. Furthermore, the architecture of block copolymers of PCL and PDMAEMA was varied to investigate effects on morphology/crystallinity and adsorption behavior. In addition, poly(butadiene) was also evaluated as the hydrophobic block in the form of cationic and anionic triblock copolymers.

    Polystyrene (PS) was covalently grafted from CNF and used as reinforcement in PS-based composites. In an attempt to determine stress transfer from matrix to CNF, a method based on Raman spectroscopy was utilized.

    Covalent grafting and physical adsorption of PCL from/onto CNF were compared by incorporating modified CNF in PCL matrices. Both approaches resulted in improved mechanical properties compared to unmodified CNF, but even at low amounts of modified CNF, covalent grafting gave tougher materials and indicated higher interfacial adhesion.

  • 7.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Javakhishvili, Irakli
    Technical University of Denmark.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Hvilsted, Søren
    Technical University of Denmark.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Preparation and evaluation of triblock copolymers based on poly(2-(dimethylamino)ethyl methacrylate) and poly(epsilon-caprolactone)2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, p. 613-POLY-Article in journal (Other academic)
    Abstract [en]

    In this work, the preparation of two block copolymers based on poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(ε-caprolactone) (PCL) has been conducted, creating the triblock copolymers PDMAEMA-b-PCL-b-PDMAEMA and PCL-b-PDMAEMA-b-PCL. The PDMAEMA-part was then quaternized, to give polyelectrolytes with either one or two charged block(s). Subsequently, differences in properties were studied in the solid state, in solution and in water dispersion with techniques including differential scanning calorimetry, size exclusion chromatography and dynamic light scattering.

  • 8.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Javakhishvili, Irakli
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Hvilsted, Søren
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Well-defined ABA- and BAB-type block copolymers of PDMAEMA and PCL2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 49, p. 25809-25818Article in journal (Refereed)
    Abstract [en]

    Triblock copolymers of ABA- and BAB-type consisting of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, A) and poly(epsilon-caprolactone) (PCL, B) have successfully been prepared. PDMAEMA-b-PCL-b-PDMAEMA (ABA) and PCL-b-PDMAEMA-b-PCL (BAB) were synthesised by a combination of ring-opening polymerisation of epsilon-CL, atom transfer radical polymerisation of DMAEMA and end-group conversion, performed through either acylation or azide-alkyne "click" chemistry. All samples were analysed by size exclusion chromatography where it was found that the evaluation of PDMAEMA-containing polymers was difficult due to the thermoresponsivity of PDMAEMA, affecting the solubility of the polymer in the temperature range at which the SEC was operated. From differential scanning calorimetry measurements it was shown that the crystallinity could be altered by changing the order of the blocks; with PDMAEMA as the outer block (ABA), the inherent crystallinity of PCL was destroyed while with PCL as the outer block (BAB), the degree of crystallinity was in the same proximity as for a PCL homopolymer.

  • 9.
    Bruce, Carl
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nilsson, Camilla
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Fogelström, Linda
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Paper sheets and laminates based on PCL- and PLLA-grafted fibers2011Conference paper (Refereed)
  • 10.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Javakhishvili, Irakli
    Technical University of Denmark.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Hvilsted, Søren
    Technical University of Denmark.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Preparation and evaluation of well-defined di- and triblock copolymers based on poly[2-(dimethylamino)ethyl methacrylate] and poly(ε-caprolactone)2014In: ACS National Meeting, 2014Conference paper (Refereed)
    Abstract [en]

    In this work, di- and triblock copolymers based on poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(ε-caprolactone) (PCL) have been prepared. The PDMAEMA length was kept constant for both di- and triblock copolymers, while in the diblock copolymers the PCL length was varied in three different lengths, yielding three separate block copolymers. For the triblock blockcopolymers, on the other hand, also the PCL blocks were of the same length yielding one ABA- and one BAB-type block copolymer. In the next step, the PDMAEMA-part was quaternized to yield polyelectrolytes with either one or two charged block(s). In the final step, difference in adsorption behavior onto a negatively charged cellulose surface and subsequent alteration of surface properties was investigated. Overall, the polymers were evaluated in solid state, in solution, in water dispersion, and on cellulose surfaces with techniques including differential scanning calorimetry, size exclusion chromatography, dynamic light scattering and quartz crystal microbalance.

  • 11.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Larsson, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Carlmark, Anna
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Fogelström, Linda
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Malmström, Eva
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    A comparative study of covalent grafting and physical adsorption of PCL onto cellulose2012Conference paper (Refereed)
    Abstract [en]

    A growing concern for the environment has, in the past years, directed the research towards a bigger focus on new “greener” materials, such as cellulose-reinforced options. Cellulose is the most abundant organic raw material in the world and it is a versatile material. However, to be able to use it in applications where it is not inherently compatible, a modification is often necessary.1-3 One common method to achieve this modification is to graft polymers onto/from the cellulose chain. This can change the inherent properties of cellulose to attain new properties, such as dimensional stability and water repellency.3 In addition to this, it has been shown that polyectrolytes can be physiosorbed onto charged surfaces.4 Due to this, it is possible to physically modify cellulose by adsorbing a polymer through electrostatic interactions instead of attaching it with a covalent bond.5

    However, a more detailed investigation concerning differences of covalent and physical attachment of poly(ε-caprolactone) (PCL) onto cellulose, has to the author’s best knowledge not been performed. Therefore, this project aims to compare these two techniques. Covalently bonded PCL was grafted by surface-initiated ring opening polymerization (SI-ROP) from the cellulose. For the adsorption approach, a block copolymer consisting of PCL and a shorter segment of poly(di(methylamino)ethyl methacrylate) (PDMAEMA) was made combining ROP and atom transfer radical polymerization (ATRP). The PDMAEMA-part was then quaternized, which resulted in a cationically charged chain – a polyelectrolyte. This can then be used as an electrostatic linker allowing the PDMAEMA-PCL copolymer to be adsorbed onto the negatively charged cellulose model surface. Finally, differences between the two approaches are evaluated regarding for example surface coverage and grafting/physiosorption efficiency investigated with techniques such as atomic force microscopy (AFM).

  • 12.
    Bruce, Carl
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Utsel, Simon
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Larsson, Emma
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Carlmark, Anna
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Fogelström, Linda
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Preparation and evaluation of a block copolymer compatibilizer for biocomposite applications2012Conference paper (Refereed)
    Abstract [en]

    In this study, a comparison between covalent grafting and physical adsorption of PCL onto a nanocellulose model surface was conducted. For the covalent attachment, surface-initiated ring-opening polymerization (SI-ROP) was performed. For the physical attachment, a charged block copolymer consisting of PCL and quaternized PDMAEMA was synthesized by ROP and ATRP, and adsorbed to the cellulose. Finally, differences in between the two substrates were investigated with techniques such as AFM.

  • 13.
    Bruce, Carl
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Utsel, Simon
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Larsson, Emma
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Fogelström, Linda
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Comparative study of covalent grafting and physical adsorption of PCL onto cellulose2012Conference paper (Refereed)
    Abstract [en]

    In this work, an investigation concerning differences between covalent and physical attachment of poly(ε-caprolactone) (PCL) to a nanocellulose modell surface was conducted. For the covalent attachment, ring-opening polymerization (ROP) was performed using the “grafting-from” approach, building the polymer from the surface. For the physical attachment, a block copolymer consisting of PCL and poly(di(methylamino)ethyl methacrylate) (PDMAEMA) was made combining ROP and atom transfer radical polymerization (ATRP). The PDMAEMA-part was then quaternized, which resulted in a charged chain – a polyelectrolyte. The charges allow for the PDMAEMA-PCL copolymer to be adsorbed onto the nanocellulose modell surface. The length of the PDMAEMA-part was kept constant (DP=20), and the length of PCL was varied (DP=150, 300, 600) for both the covalently attached polymer and for the copolymer. Finally, differences between the two approaches were evaluated regarding for example surface coverage and grafting/physiosorption efficiency investigated with techniques such as atomic force microscopy.

  • 14.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Larsson, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Malmström Jonsson, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Comparative study of covalent grafting and physical adsorption of PCL onto cellulose2012In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 243Article in journal (Other academic)
  • 15.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Physical Tuning of Cellulose-Polymer Interactions Utilizing Cationic Block Copolymers Based on PCL and Quaternized PDMAEMA2013Conference paper (Refereed)
    Abstract [en]

    In this study, the aim was to prepare and evaluate a block copolymer that can be used as a compatibilizer in cellulose fiber-reinforced biocomposites. It is an amphiphilic block copolymer consisting of poly(ε-caprolactone) (PCL), prepared with  ring-opening polymerization (ROP)1, and a shorter segment of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) synthesized with atom transfer radical polymerization (ATRP)2. The PDMAEMA-part was prepared in one single length, while the PCL-part was varied in three different lengths. In the last synthesis step the PDMAEMA-part was quaternized, turning it into a cationically charged chain – a polyelectrolyte. The block copolymers were then able to form cationic micelles in water, from where they can adsorb, under mild conditions, to anionic surfaces such as silicon oxide and cellulose-model surfaces. A similar concept has been investigated earlier in a system fully prepared with ATRP3. Additionally, physical adsorption of micelles is a milder approach of attaching a polymer to a cellulose surface compared to more traditional covalent attachment4, making it an interesting option to use in industry. After adsorption, the surface had a more hydrophobic character shown with contact angle measurements, and with AFM force measurements, it was demonstrated that there is a clear entanglement behavior obtained between the block copolymers and a PCL surface at about 60 °C, which is of importance for the information regarding the adhesive interface in a future biocomposite.

  • 16.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Physical Tuning of Cellulose-Polymer Interactions Utilizing Cationic Block Copolymers Based on PCL and Quaternized PDMAEMA2013Conference paper (Refereed)
    Abstract [en]

    In this study, the aim was to prepare and evaluate a block copolymer that can be used as a compatabilizer in cellulose fiber-reinforced biocomposites. It as an amphiphilic block copolymer consisting of poly(ε-caprolactone) (PCL), made with  ring-opening polymerization (ROP), and a shorter segment of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) that was synthesized with atom transfer radical polymerization (ATRP). The PDMAEMA-part was made in one single length, while the PCL-part was varied in three different lengths; in total were three block copolymers prepared. In the last step of the synthesis, the PDMAEMA-part was quaternized that turns it into a cationically charged chain – a polyelectrolyte. The block copolymers were then able to form cationic micelles in water, from where they can adsorb, under mild conditions, to anionic surfaces such as silicon oxide and cellulose-model surfaces. This provides the surface with a more hydrophobic character shown with contact angle measurements. Finally, with atomic force microscopy (AFM) force measurements, it was demonstrated that there is a clear entanglement behavior obtained between the block copolymers and a PCL surface at about 60 °C, which is of importance for the information regarding the adhesive interface in a future biocomposite.

  • 17.
    Bruce, Carl
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Larsson, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Preparation and evaluation of a block copolymer compatibilizer for biocomposite applications2012Conference paper (Refereed)
    Abstract [en]

    In this study, the concept of using a free polymer as a compatibilzer in biocomposite applications has been evaluated with focus on the polymer poly(ɛ-caprolactone) (PCL), commonly used in conventional grafting onto/from cellulose. A block copolymer consisting of PCL and a shorter segment of poly(di(methylamino)ethyl methacrylate) (PDMAEMA) was made combining ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The length of the PDMAEMA-part was kept constant, and the PCL-part was varied in three different lengths, yielding three separate block copolymers. As a final step, the PDMAEMA-part was quaternized, which resulted in cationically charged chains –polyelectrolytes. The charged part could then be used as an electrostatic linker allowing the PDMAEMA-PCL copolymer to be adsorbed onto negatively charged cellulose model surfaces. Finally, these cellulose model surfaces were evaluated regarding for example amount of polymer adsorbed and hydrophobic character, investigated with techniques such as quartz crystal microbalance (QCM) and contact angle measurements.

  • 18.
    Carlsson, Linn
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Surface-initiated ring-opening polymerization from cellulose model surfaces monitored by a Quartz Crystal Microbalance2012In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 8, no 2, p. 512-517Article in journal (Refereed)
    Abstract [en]

    Polymer surface-grafting is an excellent method to modify the properties of a surface. However, surface-initiated polymerization is still relatively poorly understood due to the lack of appropriate characterization methods and tools to monitor the polymerizations. Herein, we report the in situ, surface-initiated ring-opening polymerization (SI-ROP) investigated in real time by the Quartz Crystal Microbalance (QCM) technique. The polymerization was performed from a cellulose model surface and the polymerization was initiated directly from the available hydroxyl groups on the cellulose. The cyclic monomer 3-caprolactone and an organic catalyst, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), were used, and the reaction was performed in bulk at room temperature. Since a free polymer was formed in bulk in parallel to the grafting from the surface, the reaction was performed in three cycles with rinsing steps in between to measure only the effect of the surface grafting. The change in frequency showed that the grafted amount of polymer increased after each cycle indicating that most of the chain ends remained active. After polymer grafting, the cellulose model surface showed a more hydrophobic character, and the surface roughness of the cellulose model surface was reduced. This study clearly shows that QCM is a viable method to monitor SI-ROP in situ from cellulose surfaces. We believe this is an important step towards a deeper understanding of how to tailor the interface between polymer-modified cellulose and a polymer matrix in biocomposites.

  • 19.
    Carrick, Christopher
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Immunoselective cellulose nanospheres by antibody conjugation2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, p. 727-COLL-Article in journal (Other academic)
  • 20.
    Eric, Linvill
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Dynamic Mechanical Thermal Analysis Data of Sheets Made from Wood-Based Cellulose Fibers Partially Converted to Dialcohol Cellulose2017Data set
    Abstract [en]

    This data article contains the dynamic mechanical thermal analysis (DMTA) results for sheets made from cellulose fibers partially converted to dialcohol cellulose. See Larsson and Wågberg [1] for a description and characterization of the material as well as how the material is produced. See also Linvill et al. [2] for tensile testing and 3-D forming of the material. The DMTA tests were conducted at four different relative humidity levels: 0, 50, 60, and 70 % RH, and the temperature was swept between 10 and 113 °C. The DMTA results enable the understanding of the elastic, viscoelastic, and viscoplastic mechanical properties of this material at a wide range of temperature and relative humidity combinations.

  • 21.
    Erik, Johansson
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Molecular Interactions in Thin Films of Biopolymers, Colloids and Synthetic Polyelectrolytes2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of the layer-by-layer (LbL) technique has turned out to be an efficient way to physically modify the surface properties of different materials, for example to improve the adhesive interactions between fibers in paper. The main objective of the work described in this thesis was to obtain fundamental data concerning the adhesive properties of wood biopolymers and LbL films, including the mechanical properties of the thin films, in order to shed light on the molecular mechanisms responsible for the adhesion between these materials.

    LbLs constructed from poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA), starch containing LbL films, and LbL films containing nanofibrillated cellulose (NFC) were studied with respect to their adhesive and mechanical properties. The LbL formation was studied using a combination of stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D) and the adhesive properties of the different LbL films were studied in water using atomic force microscopy (AFM) colloidal probe measurements and under ambient conditions using the Johnson-Kendall-Roberts (JKR) approach. Finally the mechanical properties were investigated by mechanical buckling and the recently developed SIEBIMM technique (strain-induced elastic buckling instability for mechanical measurements).

    From colloidal probe AFM measurements of the wet adhesive properties of surfaces treated with PAH/PAA it was concluded that the development of strong adhesive joints is very dependent on the mobility of the polyelectrolytes and interdiffusion across the interface between the LbL treated surfaces to allow for polymer entanglements.

    Starch is a renewable, cost-efficient biopolymer that is already widely used in papermaking which makes it an interesting candidate for the formation of LbL films in practical systems. It was shown, using SPAR and QCM-D, that LbL films can be successfully constructed from cationic and anionic starches on silicon dioxide and on polydimethylsiloxane (PDMS) substrates. Colloidal probe AFM measurements showed that starch LbL treatment have potential for increasing the adhesive interaction between solid substrates to levels beyond those that can be reached by a single layer of cationic starch. Furthermore, it was shown by SIEBIMM measurements that the elastic properties of starch-containing LbL films can be tailored using different nanoparticles in combination with starch.

    LbL films containing cellulose I nanofibrils were constructed using anionic NFC in combination with cationic NFC and poly(ethylene imine) (PEI) respectively. These NFC films were used as cellulose model surfaces and colloidal probe AFM was used to measure the adhesive interactions in water. Furthermore, PDMS caps were successfully coated by LbL films containing NFC which enabled the first known JKR adhesion measurements between cellulose/cellulose, cellulose/lignin and cellulose/glucomannan. The measured adhesion and adhesion hysteresis were similar for all three systems indicating that there are no profound differences in the interaction between different wood biopolymers. Finally, the elastic properties of PEI/NFC LbL films were investigated using SIEBIMM and it was shown that the stiffness of the films was highly dependent on the relative humidity.

  • 22.
    Erlandsson, Johan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Duran, Veronica Lopez
    Granberg, Hjalmar
    Innventia AB.
    Sandberg, Mats
    Acreo Swedish ICT AB.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Macro- and mesoporous nanocellulose beads for use in energy storage devices2016In: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 5, p. 246-254Article in journal (Refereed)
    Abstract [en]

    Chemically cross-linked, wet-stable cellulose nanofibril (CNF) aerogel beads were fabricated using a novel procedure. The procedure facilitated controlled production of millimetre-sized CNF aerogel beads without freeze-drying or critical point drying, while still retaining a highly porous structure with low density. The aerogel beads were mechanically robust in the dry state, supporting loads of 1.3 N at 70% compression, even after being soaked in water and re-dried. Furthermore, they displayed both a good stability in water and a remarkably good shape recovery after wet compression. Owing to the stability in water, the entire surface of the highly porous aerogel beads could be successfully functionalized with polyelectrolytes and carboxyl-functionalized single-wall carbon nanotubes (CF-SWCNTs) using the Layer-by-Layer technique, introducing a significant electrical conductivity (1.6 mS/cm) to the aerogel beads. The functionalized, electrically conducting aerogel beads could carry as much as 2 kA/cm(2) and act as electrodes in a supercapacitor displaying a stabilized charge storage capacity of 9.8 F/g after 50 charging-discharging cycles.

  • 23.
    Fall, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Stefan B.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Sprakel, Joris
    Lofroth, Jan-Erik
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Shear-stiffening cellulose nanofibre gels with tuneable mechanical characteristics2011Conference paper (Other academic)
    Abstract [en]

    Gels have been synthesized from the renewable, strong and low cost cellulose nanofibres; nanofibrillated cellulose (NFC). The gels are shown to exhibit pronounced shear-stiffening properties and large extensibility (above 100%). The stiffening is due to strain induced orientation of the nanofibers, which is enabled by the free rotation at the particle-particle joints. The gels are synthesized from low concn. aq. NFC solns. By decreasing the electrostatic double-layer repulsion between the NFC fibrils, aggregation is initiated and a fluid-gel transition occurs. This transition can be detected within a range of vol. fractions. We characterize the gel microstructures using dynamic light scattering and the mech. properties using a rheometer. The mech. properties of these gels are tuneable; significantly different properties are seen if gels are formed by reducing pH or by increasing ionic strength. It is also obsd. that the properties of the gels depend on the type of counter-ion. [on SciFinder(R)]

  • 24.
    Fall, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Biofibre Materials Centre, BiMaC.
    Lindström, Stefan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Sundman, Ola
    Department of Forest Products Technology, Aalto, Finland.
    Ödberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Colloidal Stability of Aqueous Nanofibrillated Cellulose Dispersions2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 18, p. 11332-11338Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils constitute an attractive raw material for carbon-neutral, biodegradable, nanostructured materials. Aqueous suspensions of these nanofibrils are stabilized by electrostatic repulsion arising from deprotonated carboxyl groups at the fibril surface. In the present work, a new model is developed for predicting colloidal stability by considering deprotonation and electrostatic screening. This model predicts the fibril-fibril interaction potential at a given pH in a given ionic strength environment. Experiments support the model predictions that aggregation is induced by decreasing the pH, thus reducing the surface charge, or by increasing the salt concentration. It is shown that the primary mechanism for aggregation upon the addition of salt is the surface charge reduction through specific interactions of counterions with the deprotonated carboxyl groups, and the screening effect of the salt is of secondary importance.

  • 25.
    Gimåker, Magnus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Shear strength development between couched papers during dryingManuscript (preprint) (Other (popular science, discussion, etc.))
    Abstract [en]

    The out-of-plane properties (e.g., out-of-plane shear strength) of paper materials are very important for their performance during converting and end use. There is, however, a lack of published data on how shear strength develops throughout the stages of paper manufacturing. The present study investigates how the shear strength developed between couched sheets during drying in a Rapid-Köthen laboratory sheet drier. The shear strength of sheets was measured, starting from sheets with a solids content of approximately 35% all the way to fully dry sheets. Shear strength development was examined between both never-dried and rewetted sheets made of unbeaten and beaten pulp. The results indicate that the shear strength increased with increasing solids content at all solids contents investigated. The shear strength was low (<120 kPa) up to a solids content of approximately 60–70%, after which it increased rapidly with increasing solids content, suggesting that interactions important for the shear strength of dry paper start to develop at this particular dry content.

  • 26.
    Gimåker, Magnus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Östlund, Magnus
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Influence of beating and chemical additives on residual stresses in paper2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 4, p. 445-451Article in journal (Refereed)
    Abstract [en]

    Residual stresses are the stresses remaining in a material when all external forces are removed. Residual stresses in paper can influence the converting and end-use performance. There are well-established methods for determining residual stresses in paper, and some knowledge exists of how to control and tailor the residual stresses. However, there is an increasing demand to be able to tailor paper grades with respect to their mechanical properties. Pulp fibres are commonly beaten to improve the mechanical performance, but beating also increases the sheet density, de-watering resistance, and residual stresses of the paper produced. This work examines whether beating and the addition of chemical additives, i.e., a single layer of poly(allylamine) or a multilayer of poly(allylamine) and poly(acrylic acid), exert different effects on the build-up of residual stresses in paper. Both beating the fibres and adding polyelectrolytes increased the in-plane strength, stiffness, and residual stresses of the paper sheets prepared. The fact that the residual stresses did not scale linearly with the stiffness of the prepared sheets suggests that both beating and polyelectrolyte addition made the fibre/fibre joints transfer load at a lower solids content, such that stresses were transferred between fibre layers in the sheet earlier in the drying process, thus increasing the residual stresses. The fact that the strength gain when building polyelectrolyte multilayers induced less residual stresses than when the strength was increased by beating indicates the possibilities for producing paper with high strength but less residual stress.

  • 27.
    Gustafsson, Emil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Marais, Andrew
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Johansson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    The use of thin, tailored Layer-by-Layer (LbL) films to improve the mechanical properties of fibrous networks2012Conference paper (Other academic)
  • 28.
    Hagman, Anton
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Huang, Hui
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Investigation of shear induced failure during SCT loading of paperboards2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 3, p. 415-429Article in journal (Refereed)
    Abstract [en]

    In-plane compression has been analyzed experimentally and numerically using three machine made multiply paperboards. The paperboards had different shear strength profiles. Both short span compression (SCT) and long span compression (LCT) were performed. A finite element model of the SCT setup was developed, and the experimental results in MD and CD could be well predicted by the model. Using the model we could identify that the SCT failure was initiated by shearing of the interfaces in combination with the onset of plasticity in the loading direction. The model was used to make a parameter study. It showed that increased SCT values can be achieved by increasing the stiffness of the board or increase the failure displacement. The increase of stiffness was associated with ply properties, while the failure displacement was associated with interface properties.

  • 29.
    Hagman, Anton
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, M.
    Thermographical Analysis of Paper During Tensile Testing and Comparison to Digital Image Correlation2017In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 57, no 2, p. 325-339Article in journal (Refereed)
    Abstract [en]

    The thermal response in paper has been studied by thermography. It was observed that an inhomogeneous deformation pattern arose in the paper samples during tensile testing. In the plastic regime a pattern of warmer streaks could be observed in the samples. On the same samples digital image correlation (DIC) was used to study local strain fields. It was concluded that the heat patterns observed by thermography coincided with the deformation patterns observed by DIC. Because of its fibrous network structure, paper has an inhomogeneous micro-structure, which is called formation. It could be shown that the formation was the cause of the inhomogeneous deformations in paper. Finite element simulations was used to show how papers with different degrees of heterogeneity would deform. Creped papers, where the strain at break has been increased, were analysed. For these paper it was seen that an overlaid compaction of the paper was created during the creping process. During tensile testing this was recovered as the paper network structure was strained.

  • 30.
    Hagman, Anton
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Investigation of sample-size effects on in-plane tensile testing of paperboard2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 295-304Article in journal (Refereed)
    Abstract [en]

    The impact of sample size on in-plane strain behavior in paperboard was investigated, with the aim to explore the differences between local and global properties in paperboard, and try to pinpoint the mechanisms behind such differences. The local properties are of interest in converting as well as for future 3D forming of paperboard. It is important to identify differences in behavior between local and global properties since most paperboards are evaluated against the latter. The methods used for evaluation were tensile tests in controlled environment and speckle photography. The results show that there is a difference in strain behavior that is dependent of the length to width ratio of the sample, that this behavior cannot be predicted by standard tensile tests and that it depends on the board composition. The speckle analysis revealed that the behavior is a result of the activation of strain zones in the sample. These zones are relatively constant in size and therefore contribute differently to total strain in samples of different size.

  • 31.
    Hagman, Anton
    et al.
    RISE BioEconomy.
    Timmerman, Brita
    Iggesund Paperboard.
    Nygårds, Mikael
    RISE BioEconomy.
    Lundin, Andreas
    Barbier, Christophe
    BillerudKorsnäs AB.
    Fredlund, Mats
    Stora Enso.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Experimental and numerical verification of 3D-forming2017In: ADVANCES INPULP AND PAPERRESEARCH,OXFORD 2017: Transactions of the 16th Fundamental Research Symposium, Pembroke College, Oxford, England, September 3-8, 2017 / [ed] Warren Batchelor and Daniel Söderberg, 2017, Vol. 1, p. 3-26Conference paper (Refereed)
    Abstract [en]

    Motivated by sustainability arguments there is a recent interest informing of advanced structures in paper and paperboard. Therefore,in this paper, hydro-forming of papers and the effect of different fibreraw materials, beating, strength additives (PVAm), grammage andwet and dry papers have been investigated experimentally andnumerically.The experiments were carried out in laboratory hydro-formingdevice. Softwood sheets performed better than hardwood sheets,since they had higher strain at break. The ability of paper to withstandhydro-forming successfully was primarily dependent of the strain atbreak of the paper in relation to the straining required to fill the mould.Forming of wet sheets were also investigated; overall the wet sheetsformed better than the dry sheets, which was due to higher strain atbreak and lower elastic energy. Since the forming was displacementcontrolled, there was no significant difference in the effects of beating,amount of PVAm or grammage.

    Finite element modelling was performed to identify local strainsand predict problematic regions. Simulations were also performed todetermine how anisotropic sheets would behave, as well as to comparethe process of hydro-forming with press-forming. The papers couldbe strained to higher strain levels than the measured strain at breakbecause the paper is supported by the membrane and mould duringthe forming operation. The maximum strain a paper can withstandcan be increased if the paper can slide into the mould, i.e. by havinga lower coefficient of friction between the steel mould and thepaperboard.During hydro-forming the paper is supported by a rubber membrane,which gives lower strain levels than the corresponding press-formingoperation due to the difference in how the paper is deformed. Pressformingtherefore required paper with higher strain at break. Higherfriction results in more paper being pulled into the mould, whichcontributes to wrinkling of the paper. Simulation of tray forming of acreased sample was performed, which showed that high friction orcompliant creases decreased the circumferential compression.

  • 32.
    Hansson, Susanne
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Tischer, Thomas
    Karlsruhe Institute of Technology (KIT).
    Goldmann, Anja S.
    Karlsruhe Institute of Technology (KIT).
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Barner-Kowollik, Christopher
    Karlsruhe Institute of Technology (KIT).
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Comparison of the grafting-from and grafting-to approaches when modifying cellulose via ARGET ATRP2012Conference paper (Other academic)
  • 33.
    Hansson, Susanne
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Tischer, Thomas
    Karlsruhe Institute of Technology (KIT).
    Goldmann, Anja S.
    Karlsruhe Institute of Technology (KIT).
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Barner-Kowollik, Christopher
    Karlsruhe Institute of Technology (KIT).
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Comparison of the grafting-from and grafting-to approaches when modifying cellulose via ARGET ATRP2012Conference paper (Other academic)
  • 34.
    Hellwig, Johannes
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    López Durán, Vernica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Measuring elasticity of wet cellulose fibres with AFM using indentation and a linearized Hertz model2018In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 10, no 31Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of different pulp fibres in liquid were measured using an atomic force microscope. Specifically a custom-made sample holder was used to indent the fibre surface, without causing any motion, and the Young's modulus was calculated from the indentation using a linearized Hertz model.

  • 35.
    Hirn, Ulrich
    et al.
    Graz University of Technology, Austria.
    Schennach, R.
    Graz University of Technology, Austria.
    Ganser, C.
    Montanuniversität, Leoben, Austria.
    Magnusson, Mikael S.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Teichert, C.
    Montanuniversität, Leoben, Austria.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    The Area of Molecular Contact in Fiber-Fiber Bonds2013In: Advances in Pulp and Paper Reserach, Cambridge 2013: Transactions of the 15th Fundamental Research Symposium / [ed] S.J. I'Anson, 2013, p. 201-223Conference paper (Refereed)
    Abstract [en]

    We are presenting a coherent theoretical concept as well as empirical evidence suggesting that there is a high degree of molecular contact in fiberfiber bonds, the surfaces might even be in full contact.

    Fundamental theoretical relations from contact mechanics governing the area in molecular contact between surfaces are reviewed and proposed for the quantitative analysis of the area in molecular contact in fiber-fiber bonds.

    The key parameters determining the degree of molecular contact according to the theory are indentation hardness and elastic modulus of the wet pulp fibers, surface roughness of the wet fibers and the pressure applied to the fiber bonds during bond formation.

    We provide results for fiber indentation hardness and effective elastic modulus from nanoindentation measurements of fiber surfaces at varying relative humidity and in water. The fiber surface properties have been determined with an atomic force microscopy technique specifically designed to measure soft, viscoelastic materials. Also, surface roughness has been measured in the wet and dry state.

    Experiments with individual fiber-fiber joints show that the breaking strength of these joints is independent from the pressure during bond formation indicating that the surfaces in fiber-fiber bonds are in a high degree of molecular contact, maybe even full contact. This is the case even if they are formed without external pressure. Computer simulations of the degree of mechanical contact of fiber surfaces during drying were performed indicating that capillary adhesion is pulling the fiber surfaces into a high degree of molecular contact. These findings are discussed with respect to the literature considering FRET microscopy and Transmission Electron Microscopy of fiber-fiber bonds.

  • 36.
    Hollertz, Rebecca
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    López Durán, Vernica
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Larsson, Per A.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Chemically modified cellulose micro- and nanofibrils as paper-strength additives2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 9, p. 3883-3899Article in journal (Refereed)
    Abstract [en]

    Chemically modified cellulose micro- and nanofibrils were successfully used as paper strength additives. Three different kinds of cellulose nanofibrils (CNFs) were studied: carboxymethylated CNFs, periodate-oxidised carboxymethylated CNFs and dopamine-grafted carboxymethylated CNFs, all prepared from bleached chemical fibres of dissolving grade, and one microfibrillated cellulose from unbleached kraft fibres. In addition to mechanical characterization of the final paper sheets the fibril retention, sheet density and sheet morphology were also studied as a function of addition of the four different cellulose fibrils. In general, the cellulose fibrils, when used as additives, significantly increased the tensile strength, Young’s modulus and strain-at-break of the paper sheets. The effects of the different fibrils on these properties were compared and evaluated and used to analyse the underlying mechanisms behind the strengthening effect. The strength-enhancing effect was most pronounced for the periodate-oxidised CNFs when they were added together with polyvinyl amine (PVAm) or poly(dimethyldiallylammonium chloride) (pDADMAC). The addition of periodate-oxidised CNFs, with pDADMAC as retention aid, resulted in a 37% increase in tensile strength at a 2 wt% addition and an 89% increase at a 15 wt% addition (from 67 to 92 and 125 kNm/kg, respectively) compared to a reference with only pDADMAC. Wet-strong sheets with a wet tensile index of 30 kNm/kg were also obtained when periodate-oxidised CNFs and PVAm were combined. This significant increase in wet strength is suggested to be the result of a formation of cross-links between the aldehyde groups, introduced by the periodate oxidation, and hydroxyl groups on the lignocellulosic fibres and the primary amines of PVAm. Even though less significant, there was also an increase in wet tensile strength when pDADMAC was used together with periodate-oxidised fibrils which shows that the aldehyde groups are able to increase the wet strength without the presence of the primary amines of the PVAm. As an alternative method to strengthen the fibre network, carboxymethylated CNFs grafted with dopamine, by an ethyl dimethylaminopropyl carbodiimide coupling, were used as a strength additive. When used as an additive, these CNFs showed a strong propensity to form films on and around the fibres and significantly increased the mechanical properties of the sheets. Their addition resulted in an increase in the Young´s modulus by 41%, from 5.1 to 7.2 GPa, and an increase in the tensile strength index of 98% (from 53 to 105 kNm/kg) with 5 wt% retained dopamine-grafted CNFs.

  • 37.
    Huang, Hui
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Hagman, Anton
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Quasi static analysis of creasing and folding for three paperboards2014In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 69, no 1, p. 11-34Article in journal (Refereed)
    Abstract [en]

    The creasing and folding behavior of three paperboards have been studied both experimentally and numerically. Creasing and folding studies were performed on strips in both the machine direction and the cross machine direction. A finite element model that mimicked the experimental creasing and folding setup was developed, and the creasing and folding behavior could be well predicted for all three paperboards. An experimental characterization scheme consisting of three experiments was proposed, and was shown to be sufficient to predict the creasing and folding behavior. For the whole paperboard the shear strength profiles in the through thickness direction was determined with the notched shear test. Each ply was laid free by grinding, and density measurements and in-plane tension tests were performed on the bottom, middle and top plies of each paperboard. Instead of assuming uniform properties in each ply, the shear strength profiles were used to map the measured properties in the through thickness direction. Numerical simulations were performed when the ply and interface properties of the paperboards were altered to follow different shear strength profiles. This was done in order to mimic different production strategies. It was shown that the interface strengths mainly influenced the folding behavior. Whereas altered the ply properties affected the creasing force needed.

  • 38.
    Huang, Hui
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    A simplified material model for finite element analysis of paperboard creasing2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 4, p. 505-512Article in journal (Refereed)
    Abstract [en]

    A simplified material model to model paperboard was proposed. Paperboard was modeled as a multilayered structure with a softening interface model connecting the paperboard plies. The paperboard plies were modeled using an anisotropic elastic model with a Hill yield surface and isotropic hardening. The model has less material constants than previous models, and the material constants can more easily be determined from uniaxial experiments. The model was tested by performing simulations of creasing of paperboard with a two dimensional finite element model, that mimiced a laboratory creasing device. Creasing experiments and simulations down to two different distances were performed, where the reaction force and displacement of the male ruler were measured. Simulations and experiements were performed both in the paperboard machine direction and cross machine direction. The force-displacement curves from the simulations and experiments were compared, with good agreement.

  • 39.
    Huang, Hui
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Numerical and experimental investigation of paperboard folding2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 4, p. 452-467Article in journal (Refereed)
    Abstract [en]

    Creasing and folding of paperboard are important converting operations in manufacturing of packages. A two-dimensional finite element simulation of multiply paperboard that was creased and folded was presented, and the numerical results were compared with experimental data. The paperboard material model was defined by a combination of an anisotropic elastic-plastic continuum model with isotropic hardening and a softening interface model. Based on experimental observations of variations of properties in the thickness direction of the paperboard, a material mapping method was proposed to define the material parameter in the models. The tilted double notch shear test technique was used to measure the shear strengths for the paperboard interfaces. The material model and data were validated by simulations of the creasing process. Folding simulations were done for both paperboard machine direction and cross machine direction, to two crease depths, 0.0 mm and 0.2 mm. The simulation results were compared with experimental results, where the bending moment-rotation angle curve from the simulation and experiments showed good agreement.

     

  • 40.
    Huang, Hui
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    The dependency of shear zone lengh on the shear strength profiles in paperboard2011Report (Other academic)
    Abstract [en]

     

    In this work, the notched shear strength test (NST) has been further improved. In order to simplify and accelerate the testing procedure, the notches with declined slopes were used. With the proposed procedure, the shear strength profile in the thickness direction of a paperboard can be measured using one sheet only. By using the test setup, the dependency of shear zone length on shear strength was investigated. Experimental results show that both the measured shear strength values as well as the shear strength profile varied significantly with different shear zone length. Longer shear zone gave lower shear strength values and flatter profiles, while a shorter shear zone gave higher strength values and more pronounced shear strength profiles that better followed the paperboard ply structure.

  • 41.
    Huang, Hui
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Nygårds, Mikael
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Numerical analysis and experiments for increased understanding of cartonboard creasing and folding2012In: Verarbeitungsmaschinen und Verpackungstechnik 2012, 2012, p. 295-313Conference paper (Other academic)
    Abstract [en]

    Creasing and folding are vital processes in manufacturing of liquid and cartonboard packages. The quality of the crease and the subsequent folding is essential for good runnability and aesthetic appearance. The out-of-plane mechanical properties of cartonboard are particularly import in these processes. In this paper, recent advances in analysis of creasing and folding, using numerical simulations by means of the finite element method and the through-thickness shear strength profile of cartonboard, are presented.

    Existing methods to determine the out-of-plane shear strength of paper materials only give the strength in the weakest layer. In order to capture the through-thickness variation in shear strength the laminated notched shear test was introduced.

    In the simulations, the cartonboard was represented by a combination of continuum and cohesive models in order to capture the bulk and delamination properties, respectively. The continuum model was calibrated for each ply by testing individual plies that were isolated by grinding, and the cohesive model was calibrated using shear strength data from laminated notched shear tests.

    Results from the simulations are compared with creasing and folding experiments and the agreement is excellent considering the relative simplicity of the analysis. Finally, practical implications for trouble-shooting creasing and folding problems will be discussed.

  • 42.
    Ingverud, Tobias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Larsson, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Hemmer, Guillaume
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Rojas, Ramiro
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    High water-content thermoresponsive hydrogels via electrostatic macrocrosslinking of cellulose nanofibrils2016In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 54, no 21, p. 3415-3424Article in journal (Refereed)
    Abstract [en]

    Atom transfer radical polymerization (ATRP) has been utilized to synthesize tri- and star-block copolymers of poly(di(ethylene glycol)methyl ether methacrylate) (PDEGMA) and quaternized poly(2-(dimethylamino)ethyl methacrylate) (qPDMAEMA). The block copolymers, all with a minimum of two cationically charged blocks, were sequentially used for electrostatic macrocrosslinking of a dilute dispersion of anionic TEMPO-oxidized cellulose nanofibrils (CNF, 0.3 wt%), forming free-standing hydrogels. The cationic block copolymers adsorbed irreversibly to the CNF, enabling the formation of ionically crosslinked hydrogels, with a storage modulus of up to 2.9 kPa. The ability of the block copolymers to adsorb to CNF was confirmed by quartz crystal microbalance with dissipation monitoring (QCM-D) and infrared spectroscopy (FT-IR), and the thermoresponsive properties of the hydrogels were investigated by rheological stress and frequency sweep, and gravimetric measurements. This method was shown to be promising for the facile production of thermoresponsive hydrogels based on CNF.

  • 43. Jamialahmadi, A.
    et al.
    Trost, T.
    Östlund, Sören
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Dynamic performance of corrugated boxes2008In: Proceedings of the 16th IAPRI World Conference on Packaging, IAPRI , 2008Conference paper (Other academic)
    Abstract [en]

    This paper summarizes dynamic analysis of the interaction of corrugated boxes in transport using a pressure-mapping system. The dynamic contact forces on the contact area between boxes in both vertical and horizontal directions were measured and the position of the instantaneous Centre of Force (COF) was traced from which the pitch motion of boxes relative to each other was studied. The level-crossing diagrams of the contact forces show a Rayleigh distribution for the vertical contact and a Gaussian distribution for horizontal contacts. The contact force and acceleration power spectral density from accelerometers and pressure-mapping system were compared.

    The results show that a pressure mapping system is an interesting tool for analysis of the dynamic performance of systems of corrugated boxes under different stacking and loading conditions.

  • 44.
    Joby Kochumalayil, Jose
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Bergenstråhle-Wohlert, Malin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Bioinspired and highly oriented clay nanocomposites with a xyloglucan biopolymer matrix: Extending the range of mechanical and barrier properties2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 1, p. 84-91Article in journal (Refereed)
    Abstract [en]

    The development of clay bionanocomposites requires processing routes with nanostructural control. Moreover, moisture durability is a concern with water-soluble biopolymers. Here, oriented bionanocomposite coatings with strong in-plane orientation of clay platelets are for the first time prepared by continuous water-based processing. Montmorillonite (MTM) and a "new" unmodified biological polymer (xyloglucan (XG)) are combined. The resulting nanocomposites are characterized by FE-SEM, TEM, and XRD. XG adsorption on MTM is measured by quartz crystal microbalance analysis. Mechanical and gas barrier properties are measured, also at high relative humidity. The reinforcement effects are modeled. XG dimensions in composites are estimated using atomistic simulations. The nanostructure shows highly oriented and intercalated clay platelets. The reinforcement efficiency and effects on barrier properties are remarkable and are likely to be due to highly oriented and well-dispersed MTM and strong XG-MTM interactions. Properties are well preserved in humid conditions and the reasons for this are discussed.

  • 45.
    Joby Kochumalayil, Jose
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Morimune, Seira
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nishino, Takashi
    Walther, Andreas
    Ikkala, Olli
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nacre-mimetic xyloglucan/clay bionanocomposites prepared from hydrocolloidal suspension – a chemical modification route for preserved performance at high humidityManuscript (preprint) (Other academic)
  • 46.
    Joby Kochumalayil, Jose
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Kasai, Wakako
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Regioselective modification of a xyloglucan hemicellulose for high-performance biopolymer barrier films2013In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 93, no 2, p. 466-472Article in journal (Refereed)
    Abstract [en]

    Biobased polymers such as starch and hemicelluloses from wood are of interest for packaging applications, but suffer from limitations in performance under moist conditions. Xyloglucan from industrial tamarind seed waste offers potential, but its Tg is too high for thermal processing applications. Regioselective modification is therefore performed using an approach involving periodate oxidation followed by reduction. The resulting polymer structures are characterized using MALDI-TOF-MS, size-exclusion chromatography, FTIR and carbohydrate analysis. Films are cast from water and characterized by thermo-gravimetry, dynamic mechanical thermal analysis, dynamic water vapor sorption, oxygen transmission and tensile tests. Property changes are interpreted from structural changes. These new polymers show much superior performance to current petroleum-based polymers in industrial use. Furthermore, this regioselective modification can be carefully controlled, and results in a new type of cellulose derivatives with preserved cellulose backbone without the need for harmful solvents.

  • 47.
    Johansson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Biopolyelectrolyte Multilayers of Cationic and Anionic Starch as Adhesion Modifiers2010Conference paper (Other academic)
  • 48. Klemm, Dieter
    et al.
    Kramer, Friederike
    Moritz, Sebastian
    Lindström, Tom
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Ankerfors, Mikael
    Material Processes, Innventia AB, Sweden.
    Gray, Derek
    Dorris, Annie
    Nanocelluloses: A New Family of Nature-Based Materials2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 24, p. 5438-5466Article, review/survey (Refereed)
    Abstract [en]

    Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.

  • 49.
    Kochumalayil, Joby
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Sehaqui, Houssine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Tamarind seed xyloglucan: a promising biopolymer matrix for bioinspired nanocomposite materials2010Conference paper (Other academic)
  • 50.
    Kochumalayil, Joby
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Sehaqui, Houssine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Zhou, Qi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Biotechnology (BIO), Centres, Swedish Center for Biomimetic Fiber Engineering, BioMime.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Xyloglucan films2009Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention pertains to films comprising xyloglucan, processes for preparing films comprising xyloglucan, as well as various uses of said films as for instance packaging material. Specifically, the present invention relates to xyloglucan films having advantageous properties relating to inter alia tensile strength, elastic modulus, and strain-to-failure.

123 1 - 50 of 121
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