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  • 1.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Ji, Guangchao
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Björlin, Anders
    Kiwok AB.
    Östlund, Anders
    Kiwok AB.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Textile-Electronic Integration in Wearable Measurement Garments for Pervasive Healthcare Monitoring2015Conference paper (Other academic)
  • 2.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Guangchao, Li
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Högskolan i Borås.
    A Knitted Garment using Intarsia Technique for Heart Rate Variability Biofeedback: Evaluation of Initial Prototype.2015Conference paper (Other academic)
  • 3.
    Alexander Deen, Fusi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Synthetic Functionalization of Colloidal Lignin Particles for Wood Adhesive Applications2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Functionalizable spherical colloidal lignin particles (CLPs) represent a valuable asset for the valorization of lignin side-streams from the pulp industry. The spherical structure allows for the circumvention of the heterogeneous and poorly dispersible structure of the biopolymer. However, organic solvents and alkaline media degrade the particle structure and dissolve the polymers due to their chemical nature and solubility. The solvents will alter the aggregated polymers into irregular shapes that would correspond to inconsistent physicochemical properties. Then, the material will become unusable for advanced material applications, namely wood adhesives. In this study, a replicable process to yield pH ca. 12 stable CLPs for wood adhesives or further functionalization for other advanced material applications was developed and optimized. Lignin was functionalized with cross-linkers, glyoxal or formaldehyde, and selfassembled into spherical structures in the micro emulsification of the organic solution. The formed colloids were partially rotary evaporated to retain organic solvents within the colloidal structures, and then be cured at 73-76 °C until pH stable and further functionalized for advanced material applications. The functionalization with glyoxal was pursued further for its possibly increased reactivity and the health concerns associated with formaldehyde. The process requires the addition of glyoxal to lignin in an acidic organi cmedia at ambient temperature, and the solution to react at 64 °C. Glyoxal is likely added to the polymer structure in its hydrated and dimerized form, and its attachment to lignin should be analyzed through the behavior of glyoxal in different media. The formed colloids were rotary evaporated to an organic solvent content of 60 wt. % of the spheres to allow the occurrence of the curing reaction. These materials were finally cured by thermosetting them at 73-76 °C until pH stable. The particles can be cured with base-catalysis through the controlled addition of the base NaOH(aq). However, the mode and rate of addition of the catalyst are critically important for a nondegradative infusion of a base into solvent present ot removed particles without morphological changes. Further procedural improvement and larger batches are necessary to conduct CLP adhesive experiments.

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  • 4.
    Atarijabarzadeh, Sevil
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Biofilm adhesion on silicone materials2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Silicone composite high voltage insulators are sometimes contaminated by microorganisms in outdoor applications, which results in the insulator becoming conductive and thereafter failure of the insulators. In this work, it has been tried to develop silicone materials with antimicrobial properties. Silicone was blended with various antimicrobial agents. Affectivity and appropriate concentration of the biocides were decided through a fast test prior to the manufacturing of the samples.

    Samples were aged according to an international biodegradation test. To study the extent of the growth on the samples’ surface visual analysis and scanning electron microscopy (SEM) were performed. Samples were studied for changes in surface properties and surface chemical composition with carrying out dynamic contact angle measurements and Fourier transform infrared spectroscopy respectively. Results from the biodegradation test showed some biocides could inhibit the fungal growth comparing the results for the reference samples. Biofilm formation resulted in changes in surface hydrophobicity and surface chemical composition.

    Further, silicone materials were compounded with clay nanoparticles, which were modified with different organic compounds. Reference samples were manufactured with clay nanoparticles modified with a siloxane surfactant to make the dispersion of the particles into the silicone matrix easier. Clay nanoparticles were also grafted with two organic compounds with antimicrobial effect in order to synthesis organoclays, which have antimicrobial properties. Furthermore, grafting clay with these two compounds was also aimed to make the easy dispersion of the particles into silicone possible.

    Nanocomposites compounded with antimicrobial clay nanoparticles as well as reference nanocomposites were tested with quick test for microbial growth. Changes in the clay particles morphology were examined with x-ray diffraction as well as SEM. Manufactured nanocomposites were also examined with x-ray and SEM to study the dispersion of nanoparticles into the silicone matrix. Changes in clay morphology were observed due to modification with organic compounds. Microbial growth was inhibited on some samples due to presence of antimicrobial organoclays.

  • 5.
    Austrell, Per-Erik
    et al.
    Division of Structural Mechanics, Lund Institute of Technology.
    Kari, LeifKTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Constitutive Models for Rubber IV: proceedings of the 4th European Conference for Constitutive Models for Rubber, ECCMR 2005, Stockholm, Sweden, 27-29 June 20052005Collection (editor) (Refereed)
    Abstract [en]

    The unique properties of elastomeric materials are taken advantage of in many engineering applications. Elastomeric units are used as couplings or mountings between stiff parts. Examples are shock absorbers, vibration insulators, flexible joints, seals and suspensions etc.

     

    However, the complicated nature of the material behavior makes it difficult to accurately predict the performance of these units, using for example finite element modelling. It is therefore necessary that the constitutive model accurately capture relevant aspects of the mechanical behavior.

     

    The latest development concerning constitutive modelling of rubber is collected in these proceedings. It is the fourth ECCMR-European Conference on Constitutive Modelling in a series on this subject.

     

    Topics included in this volume are, Hyperelastic models, Strength, fracture & fatigue, Dynamic properties & the Fletcher-Gent effect, Micro-mechanical & statistical approaches, Stress softening, Viscoelasticity, Filler reinforcement, and Tyres, fiber & cord reinforced rubber.

  • 6.
    Becerra, Marley
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Friberg, Andreas
    ABB Corporate Research, Västerås.
    Arc jets blown by outgassing polymers in air2014In: Proceedings of the 20th International Conference on Gas Discharges and Their Applications GD2014, GD2014 , 2014, p. 1-4Conference paper (Refereed)
    Abstract [en]

    This paper describes experimental results about the behaviour of arc jets transversely blown in the presence of outgassing polymers (POM –CH2O– or PMMA –C5H8O2–). The arc jets are ignited in air between copper electrodes under a 2 kA, 50 Hz AC current. High speed photography and optical emission spectroscopy are used to study the mechanism leading to the increase of the arc voltage when polymers are used instead of non-ablating materials (e.g. quartz). It is found that the transversal blowing flow caused by the injection of ablation vapours have a weak effect on the arc voltage build-up. Instead, the chemical changes in the plasma environment appear to better explain the observed increase in the arc voltage when polymers are used. 

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  • 7.
    Bladholm, Viktor
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Organic Fillers for Solid Rocket Fuel2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Liquid propellant and solid propellant rockets are the most commonly used rockets

    Liquid propellant rockets have the advantage of being manoeuvrable with a high specific performance while they exhibit problems with storage and a complex design. Solid propellant rockets offer simplicity and are storable while they have a large environmental impact and could be difficult to handle. A third type of rocket, hybrid propellant rocket has the potential to combine the simplicity of solid propellant rocket with the manoeuvrability of liquid propellant rockets. While the hybrid propellant rocket offers advantages over liquid propellant and solid propellant rocket it have problems with its fuel which have a low regression rate and low density. Organic fillers were evaluated since they may increase in the regression rate and the density of the solid fuel. 50 organic fillers were assessed with regards to their specific impulse, density, cost and handling properties. The organic fillers with the most promising properties were then experimentally evaluated. Thermogravimetric analysis (TGA), isothermal weight loss test, compatibility test and differential scanning calorimetry analysis were conducted. The results indicate that hexamine, fluorene, anthracene and 1,4-dicyanobenzene are the most suitable organic fillers of those evaluated..

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  • 8.
    Bogdan, Felix
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Evaluation of different block-copolymer coatings of iron oxide nanoparticles by flash nanoprecipitation2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nanoparticles (NPs) offer unique possibilities for medical applications, including the controlled release of cancer drugs, the use as imaging contrast during imaging procedures or the hyperthermic treatment of cancer cells. Flash nanoprecipitation (FNP) produces NPs to combine these applications in a fast, cheap, and scalable coating process. The use of FNP with a Multi-Inlet Vortex Mixer (MIVM) is a promising method to easily coat hydrophobic oleic acid iron oxide NPs (IONPs) with various biocompatible block-copolymers. Amphiphilic block-copolymers based on hydrophilic polyethylene glycol (PEG) and hydrophobic poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) or poly(caprolactone) (PCL) were successfully synthesized. The organic catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was used to increase biocompatibility of the resulting polymers PEG-PLA, PEG-PL7.5KG2.5KA and PEG2K-PCL2K. The synthesis of hydroxyl terminated poly(acrylic acid) (PAA-OH) followed by the polymerization with PLGA was attempted. The amphiphilic block-copolymers were used in combination with the stabilizer polysorbate 80 (Tween80®) in FNP to form bare polymeric NPs using a MIVM as the reactor. DLS and STEM confirmed particle sizes between 50 - 100 nm. The addition of 13 ± 2 nm hydrophobic oleic acid IONPs yielded an increase in particle size as well as increase in particle stability over time. STEM images showed attachment of single IONPs to the outside of the polymeric NPs. Hydrophobic interactions between the polymer and oleic acid IONPs are possible. To achieve encapsulation of the oleic acid IONPs, adjustments to the process parameters of FNP should be considered in future research. Additional experiments are required to explore possible drug addition, release mechanisms and hyperthermia behavior of the polymer coated IONPs particles.

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  • 9.
    Brumer, Harry
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Rutland, Mark
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Sinnott, M. L.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Cross-Linking Involving a Polymeric Carbohydrate Material2005Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a method of cross-linking a polymeric carbohydrate material with a second material by means of a soluble carbohydrate polymer and a crosslinking agent. The present invention furthermore relates to the resulting cross-linked material, to uses of the cross-linked material, as well as to a kit comprising the soluble carbohydrate polymer and the cross-linking agent.

  • 10.
    Capezza, Antonio Jose
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials. SLU.
    Sustainable Biobased Protein Superabsorbents from Agricultural Co-Products2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The preparation of sustainable protein superabsorbents from agricultural industry side-streams is reported. Wheat gluten (WG), a co-product from the ethanol/starch industry, was processed into foams with sponge-like behavior and high liquid uptake. The materials were obtained by phase-separation of aqueous WG dispersions followed by ambient drying, or by lyophilization. The use of a natural and non-toxic cross-linker (genipin) resulted in foams with high water swelling properties (~18 g/g in 10 min). The rapid swelling may be of use in bio-based foams in e.g., sanitary pads.

    As an alternative, potato protein concentrate (PPC, side-stream from the starch industry), was functionalized and prepared as particles. The liquid swelling capacity was compared after acylation with five different agents. It is shown that the PPC can be acylated to replicate the chemistry of synthetic superabsorbent polymers (SAP), showing water swelling capacity >10 g/g. The acylation (using EDTAD) of WG suspensions resulted in protein particles with water and saline uptake of 22 and 5 g/g, respectively. Limited network stability was however observed when acylating WG in low-protein suspensions. This was addressed by mixing the acylated protein with genipin, which provided a stable protein network. The process gave functionalized particles with swelling capacity ~40 g/g and ~80 % retention of swelling in centrifuge retention tests.

    The extrusion of WG showed that porous WG with water uptake of 500 % can be produced. Further, the scalability of PPC production was pilot-tested by functionalizing potato fruit juice (PFJ), containing the potato protein in its soluble state before the industrial drying used to obtain PPC. This resulted in water swelling capacities >10 g/g, which was comparable to the PPC-functionalized materials. The results pave the way for future optimization of high-throughput production techniques using protein sources in mass production of sustainable protein-based SAPs.

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  • 11.
    Capezza, Antonio Jose
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Cui, Yuxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Numata, Keiji
    Lundman, Malin
    Newson, William
    Olsson, Richard
    Johansson, Eva
    Hedenqvist, Mikael
    High Capacity Functionalized Protein Superabsorbents from an Agricultural Co‐Product: A Cradle‐to‐Cradle Approach2020In: Advanced Sustainable Systems, ISSN 2366-7486Article in journal (Refereed)
    Abstract [en]

    Synthesis of superabsorbent particles from nontoxic wheat gluten (WG) protein, as an industrial co‐product, is presented. A natural molecular cross‐linker named genipin (a hydrogenated glycoside) is used together with a dianhydride (ethylenediaminetetraacetic EDTAD), to enable the preparation of a material with a network structure capable of swelling up to ≈4000% in water and ≈600% in saline solution. This represents an increase in swelling by over 10 times compared to the already highly absorbing gluten reference material. The carboxylation (using EDTAD) and the cross‐linking of the protein result in a hydrogel with liquid retention capacity as high as 80% of the absorbed water remaining in the WG network on extensive centrifugation, which is higher than that of commercial fossil‐based superabsorbents. The results also show that more polar forms of the reacted genipin are more effectively grafted onto the protein, contributing to the swelling and liquid retention. Microscopy of the materials reveals extensive nanoporosity (300 nm), contributing to rapid capillarity‐driven absorption. The use of proteins from agricultural industries for the fabrication of sustainable protein superabsorbents is herein described as an emerging avenue for the development of the next generation daily‐care products with a minimal environmental impact.

  • 12.
    Capezza, Antonio Jose
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Muneer, Faraz
    Prade, Thomas
    Newson, William
    Das, Oisik
    Lundman, Malin
    Olsson, Richard
    Hedenqvist, Mikael
    Johansson, Eva
    Revalorization of a protein side-stream: an integrated industrial approach towards non-toxic biodegradable superabsorbentsManuscript (preprint) (Other academic)
  • 13.
    Chen, Fei
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Chitosan and chitosan/wheat gluten blends: properties of extrudates, solid films and bio-foams2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents four different studis describing the characteristics and processing opportunities of two widely available biopolymers: chitosan and wheat gluten. The interest in these materials is mainly because they are bio-based and obtained as co- or by-products in the fuel and food sector

    In the first study, high solids content chitosan samples (60 wt.%) were successfully extruded. Chitosan extrusion has previously been reported but not chitosan extrusion with a high solids content, which decreases the drying time and increases the production volume. An orthogonal experimental design was used to assess the influence of formulation and processing conditions, and the optimal formulation and conditions were determined from the orthogonal experimental analysis and the qualities of the extrudates. The mechanical properties and processing-liquid mass loss of the optimized extrudates showed that the extrudates became stable within three days. The changes in the mechanical properties depended on the liquid mass loss.

    In a separate study, monocarboxylic (formic, acetic, propionic, and butyric) acid uptake and diffusion in chitosan films were investigated. It is of importance in order to be able to optimize the production of this material with the casting technique. The time of the equilibration uptake in the chitosan films exposed to propionic and butyric acid was nine months. This long equilibration time encouraged us study the exposed films further. The uptake and diffusivity of acid in the films decreased with increasing acid molecular size. A two-stage absorption curve was observed for the films exposed to propionic acid vapour. The films at the different stages showed different diffusivities. The acid transport was also affected by the structure of the chitosan films. X-ray diffraction suggested that the crystal structure of the original films disappeared after the films had been dried from their acid-swollen state, and that the microstructure of the dried films depended on the molecular size of the acid. Compared with the original films, the dried films retained their ductility, although a decrease in the molecular weight of the chitosan was detected. The water resistance of the acid-exposed films was increased, even though the crystallinity of these films was lower.

    The third study was devoted to chitosan/wheat gluten blend films cast from aqueous solutions. Different solvent types, additives and drying methods were used to examine their effects on the microstructures of the blended films. Chitosan and wheat gluten were immiscible in the aqueous blend, and the wheat gluten formed a discrete phase, and the homogeneity of the films was improved by using a reducing agent, compared with films prepared using only water/ethanol as cast media. Adding urea and surfactants resulted in a medium homogeneity of the films compared to those prepared with the reducing agents or with only water/ethanol. An elongated wheat gluten phase was observed in a film using glyoxal, in contrast to pure chitosan/wheat gluten blends. The opacity of the different films was studied. The mechanical properties and humidity uptake of the films increased with increasing chitosan content. The films containing 30 wt.% of wheat gluten showed the most promising mechanical properties, close to those of the pristine chitosan films.

    The final part describes the preparation and properties of a bio-foam composed of a blend of chitosan and wheat gluten. This foam was prepared without any porogen or frozen liquid phase to create porosity. A unique phase distribution of the chitosan and wheat gluten solutions formed without any agitation, and the foam was obtained when the liquid phase were withdrawn under vacuum. These foams showed high mass uptake of n-hexane and water in a short time due to their open pores and high porosity. The maximum uptake of n-hexane measured was 20 times the initial mass of the foam. The foams showed a high rebound resilience (94 % at 20 % compression strain) and they were not broken when subjected to bending.  

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  • 14.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gällstedt, Mikael
    Olsson, Richard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    A Novel Chitosan/Wheat Gluten Biofoam Fabricated by Mixing and Vacuum-dryingManuscript (preprint) (Other academic)
  • 15.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gällstedt, Mikael
    Olsson, Richard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Unusual Effects of Monocarboxylic Acids on The Structure and on The Transport and Mechanical Properties of Chitosan Films2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 132, p. 419-429Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to study the transport of monocarboxylic acids in chitosan films, since this is important for understanding and predicting the drying kinetics of chitosan from aqueous solutions. Despite the wealth of data on chitosan films prepared from aqueous monocarboxylic acid solutions, this transport has not been reported. Chitosan films were exposed to formic, acetic, propionic and butyric acid vapours, it was found that the rate of uptake decreased with increasing molecular size. The equilibration time was unexpectedly long, especially for propionic and butyric acid, nine months. A clear two-stage uptake curve was observed for propionic acid. Evidently, the rate of uptake was determined by acid-induced changes in the material. X-ray diffraction and infrared spectroscopy indicated that the structure of the chitosan acetate and buffered chitosan films changed during exposure to acid and during the subsequent drying. The dried films previously exposed to the acid showed less crystalline features than the original material and a novel repeating structure possibly involving acid molecules. The molar mass of the chitosan decreased on exposure to acid but tensile tests revealed that the films were always ductile. The films exposed to acid vapour (propionic and butyric acid) for the longest period of time were insoluble in the size-exclusion chromatography eluent, and they were also the most ductile/extensible of all samples studied.

  • 16.
    Chen, Yujie
    et al.
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China..
    Chen, Zhen
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China..
    Chen, Chi
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China..
    Rehman, Hafeez Ur
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China..
    Liu, Hezhou
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China..
    Li, Hua
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, State Key Lab Met Matrix Composites, Shanghai 200240, Peoples R China..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    A gradient-distributed liquid-metal hydrogel capable of tunable actuation2021In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 421, p. 127762-, article id 127762Article in journal (Refereed)
    Abstract [en]

    Although thermoresponsive hydrogels have numerous applications that range from soft robots, biomedical engineering, and actuators to sensors for artificial muscles, the existing hydrogel actuators undergo only unidirectional deformation under a single thermal stimulus and suffer from slow actuation and unstable interfacial adhesion in multiple layers. Herein, hydrogels containing gradient-distributed polydopamine-coated eutectic gallium-indium (PDA-EGaIn) nanodroplets in a poly(N-isopropylacrylamide) (PNIPAM) matrix and thus featuring a gradient distribution of thermal conductivity and an increased barrier towards water loss are shown to be capable of a rapid and tuneable thermoresponse. Notably, whereas hydrogels with a low content of PDAEGaIn undergo rapid one-way bending under a single thermal (45 degrees C) stimulus, those with a high content of PDAEGaIn undergo sequential bidirectional (bending) actuation. The ability of these hydrogels to undergo fast and tuneable actuation under a single thermal stimulus makes them suitable for use in grab-release instruments and soft robots.

  • 17.
    Claesson, Per M.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE.
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    He, Yunjuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Li, Gen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Surface Nanomechanics of Coatings and Hydrogels2019In: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2019, no 1Conference paper (Refereed)
    Abstract [en]

    Due to the increasing use of nanostructured materials and thin coatings as barrier materials, it has become of high importance to measure and understand material properties on the nm to 100 nm length scales. In this article we demonstrate and discuss how atomic force microscopy techniques can be used to this end. It is demonstrated that the classical analysis based on the assumption of a purely elastic material response is a fair approximation for relatively stiff coatings (elastic modulus order of GPa), whereas viscous responses must be considered for soft materials (apparent modulus order of MPa) such as hydrogels.

  • 18.
    Cuenca, Jacques
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Numerical acoustics.
    Van der Kelen, Christophe
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Numerical acoustics.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Numerical acoustics.
    A general methodology for inverse estimation of the elastic and anelastic properties of anisotropic open-cell porous materials-with application to a melamine foam2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 8, p. 084904-Article in journal (Refereed)
    Abstract [en]

    This paper proposes an inverse estimation method for the characterisation of the elastic and anelastic properties of the frame of anisotropic open-cell foams used for sound absorption. A model of viscoelasticity based on a fractional differential constitutive equation is used, leading to an augmented Hooke's law in the frequency domain, where the elastic and anelastic phenomena appear as distinctive terms in the stiffness matrix. The parameters of the model are nine orthotropic elastic moduli, three angles of orientation of the material principal directions and three parameters governing the anelastic frequency dependence. The inverse estimation consists in numerically fitting the model on a set of transfer functions extracted from a sample of material. The setup uses a seismic-mass measurement repeated in the three directions of space and is placed in a vacuum chamber in order to remove the air from the pores of the sample. The method allows to reconstruct the full frequency-dependent complex stiffness matrix of the frame of an anisotropic open-cell foam and in particular it provides the frequency of maximum energy dissipation by viscoelastic effects. The characterisation of a melamine foam sample is performed and the relation between the fractional-derivative model and other types of parameterisations of the augmented Hooke's law is discussed.

  • 19. Darabi, Sozan
    et al.
    Hummel, Michael
    Rantasalo, Sami
    Rissanen, Marja
    Öberg Månsson, Ingrid
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Hilke, Haike
    Byungil, Hwang
    Skrifvars, Mikael
    Hamedi, Mahiar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Sixta, Herbert
    Lund, Anja
    Müller, Christian
    Green Conducting Cellulose Yarns for Machine Sewn Electronic TextilesManuscript (preprint) (Other academic)
  • 20.
    Das, O.
    et al.
    Wood and Bionanocomposites, Material Science Division, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, 97187, Sweden.
    Kim, N. K.
    Centre for Advanced Composite Materials, Department of Mechanical Engineering, The University of Auckland, Auckland, 1142, New Zealand.
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Bhattacharyya, D.
    Centre for Advanced Composite Materials, Department of Mechanical Engineering, The University of Auckland, Auckland, 1142, New Zealand.
    Johansson, E.
    Department of Plant Breeding, Faculty of Landscape Planning, Horticulture and Crop Production Sciences, Swedish University of Agricultural Sciences, Alnarp, 23053, Sweden.
    Xu, Q.
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210014, China.
    Holder, Shima
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Naturally-occurring bromophenol to develop fire retardant gluten biopolymers2020In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 243, article id 118552Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to impart fire retardancy in wheat gluten polymer through naturally-occurring additives such as lanosol. The fire properties of lanosol were compared with two other conventional brominated fire retardants (Tetrabromobisphenol A and Hexabromocyclododecane). Samples containing fire retardants and gluten were prepared through compression moulding process and then characterised for their fire and mechanical properties. All fire retardants enhanced the reaction-to-fire and thermal properties of gluten while generating V-0 (i.e. vertical position and self-extinguished) ratings in the UL-94 test. The presence of all the fire retardants increased the modulus of the gluten polymer but the fire retardant particles were detrimental for the tensile strength. Nevertheless, lanosol addition delayed ignition and lowered peak heat release rate of gluten by the maximum amount, thereby leading to relatively higher fire performance index (compared to the other fire retardants). Lanosol also allowed the gluten to create a dense char barrier layer during burning that impeded the transfer of heat and flammable volatiles. The fact that only 4 wt% lanosol was able to cause self-extinguishment under direct flame and reduce peak heat release rate by a significant 50% coupled with its inherent occurrence in nature, raises the question if lanosol can be a potential fire retardant in polymeric systems, although it is a bromophenol.

  • 21.
    Decrop, Deborah
    et al.
    KU Leuven, Belgium.
    Pardon, Gaspard
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Kokalj, Tadej
    KU Leuven, Belgium.
    Robert, Puers
    KU Leuven, Belgium.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Lammertyn, Jeroen
    KU Leuven, Belgium.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer2015In: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    We report a novel polymer material formulation and stamp-molding technique that enable rapid single-step manufacturing of hydrophilic-in-hydrophobic microwell arrays. We developed a modified thiol-ene-epoxy polymer (mOSTE+) formulation that mimics the surface energy of its mold during polymerization. The polymer inherits the surface energy from the mold through molecular self-assembly, in which functional monomers self-assemble at the interface between the liquid prepolymer and the mold surface. Combining this novel mOSTE+ material with a stamp-molding process leads to simultaneous surface energy mimicking and micro-structuring. This method was used to manufacture microwells with hydrophilic bottom and hydrophobic sidewall, depressed in a surrounding hydrophobic surface. The microwell arrays were successfully tested for the self-assembly of 62’000 femtoliter-droplets. Such femtoliter droplet arrays are useful for, e.g., digital ELISA and single cell/molecule analysis applications.

  • 22.
    Feng, Zhaoxuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    From Polysaccharides to Functional Materials for Trace Pharmaceutical Adsorption2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The transition to bioeconomy will reduce our dependency on fossil fuels as well as contribute to a more sustainable society. Within this framework, exploitation and development of renewable substitutes to petroleum-based products provides feasible roadmap for the material design. Here a perspective is provided to how the natural polysaccharides chitosan (CS) and/or cellulose (CL) could be elaborated and transformed to high-performance materials with the explicit aim of removing trace pharmaceutical contaminants from the wastewater, thus facilitating the sustainable development. In the first part of the thesis, chitosan and cellulose were converted to the carbon spheres (C-sphere) through a microwave-assisted hydrothermal carbonization process, and C-sphere was further broken down to the nanographene oxide (nGO) via a simple oxidation route. On this foundation, a green pathway was developed for fabrication of biobased materials for wastewater purification. First, macroporous chitosan-based composite hydrogels with controllable properties were developed, where chitosan-derived nGO worked as a functional property enhancer. Second, a further development changing from the bulky hydrogels to microgels consisting of CS composite particles in the microscopic size was achieved by a fast one-pot spraying-drying process. The crosslinking reaction occurred in situ during the spray-drying. Last, the C-sphere by-itself was also believed to be a potential adsorbent for wastewater contaminants. In the next step the prepared systems were evaluated for their capacity to adsorb pharmaceutical contaminants. Diclofenac sodium (DCF) was utilized as the model drug, and the three fabricated bio-adsorbents all demonstrated effective DCF adsorption performance, with the adsorption efficiency varying from 65.6 to 100%. Moreover, the DCF adsorption kinetics, isotherms and thermodynamic study were also investigated to reveal the nature of the adsorption process with the different materials. Finally, chitosan-based microspheres were selected for the reusability study, with the adsorption efficiency above 70% retained after six adsorption-desorption cycles, thus further endowing the promising potential of the fabricated bio-adsorbents for commercial applications.

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  • 23.
    Glad, David
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    A natural-based absorbent polymer based on potato protein: Functionalized via dry acylation with high scalability2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Most superabsorbent polymers (SAP) today are produced from oil, a nonrenewable resource, which contribute to the worlds environmental problems.

    This study investigates if a dry functionalization route can increase water absorption capacity of protein concentrates, and potato protein concentrate (PPC) especially. In order to create a naturally based, biodegradable SAP trough a nontoxic process with high scalability for easy implementation at an industrial scale.

    The PPC was functionalized through acylation, trying five acylation agents (AA, A-E) at three different temperatures (T1-T3). The samples where then characterized with Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and a standardized absorption test.

    A naturally based, biodegradable SAP was created with an absorption capacity of 14 g/g (using AA A at temp T2). Four samples experienced an unexpected color shift believed to originate from Maillard and caramelization reactions as well as light scattering phenomena. These samples were also experiencing a previously undocumented solubility transformation likely originating from a highly efficient acylation process together with an insufficient amount of crosslinking. A phase separation was also found in these samples which needs further investigation.

    This dry functionalization of protein concentrates is capable of producing biodegradable SAPs but does not compete with current materials. The functionalized samples need further characterization to accurately determine the feasibility of this protocol in order to provide environmentally friendly alternatives for the future. 

  • 24.
    Grenestedt, Joakim L
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    On cracks emanating from wedges in expanded PVC foam1996In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 54, no 4, p. 445-456Article in journal (Refereed)
    Abstract [en]

    An experimental and analytical study was made on the effect of stress singularities on the strength of expanded PVC foam materials of different densities. Experiments were performed on specimens with different wedge geometries ranging from sharp cracks, with the ordinary inverted square root stress singularity, to shallow re-entrant corners with weak singularities. A brittle fracture criterion based on a generalised stress intensity factor, called Q, at the wedge tip was fit to experimental data. The critical stress intensity factor, Qcr, for crack initiation depends on the wedge geometry. This dependence was estimated from simple point-stress criteria and a criterion due to Seweryn [Brittle fracture criterion for structures with sharp notches. Engng Fracture Mech. 47, 673-681 (1994)], and good agreement with experimental data was obtained. When the point-stress criterion was applied to Mode II sharp cracks, poor agreement with published data was found. A critical study of the Mode II crack specimen was therefore initiated, leading to the conclusion that the commonly used specimen gives erroneous values of KIIc and the reason seems to be due to crack surface friction. A new Mode II crack specimen which eliminates crack surface friction was proposed and tested, and good agreement with the point-stress criterion was obtained. A criterion for homogeneous materials proved to be adequate also for the porous PVC foams.

  • 25.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fu, Qiliang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Recyclable and superelastic aerogels based on carbon nanotubes and carboxymethyl cellulose2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 159, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Deformation mechanisms are largely unknown for superelastic carbon nanotube (CNT) aerogels, and this hampers materials design efforts. The CNT network in the cell walls is typically crosslinked or connected by a thermoset polymer phase. In order to create a recyclable superelastic aerogel, unmodified single or multi-walled CNTs were dispersed in water by adding to aqueous carboxymethyl cellulose (CMC) solution. Directional freeze-drying was used to form honeycombs with cell walls of random-in-the-plane CNTs in CMC matrix. Cell wall morphology and porosity were studied and related to CNT type and content, as well as elastic or plastic buckling of the cell walls under deformation. CMC acts as a physical crosslinker for the CNTs in a porous cell wall. Aerogel structure and properties were characterized before and after recycling. The conductivity of the composite aerogel with a density of 10 kg/m3, 99% porosity and 50 wt % single-walled CNT exceeds 0.5 S/cm. The potential of these superelastic and conductive aerogels for applications such as mechanoresponsive materials was examined in cyclic conductivity tests at different strains. This opens a new route for recyclable superelastic CNT composite aerogels, avoiding material loss, chemical treatment or addition of other components.

  • 26.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wang, Zhen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Berglund, Lars. A
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hamedi, Mahiar M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cellulose Nanopaper with Monolithically Integrated Conductive Micropatterns2019In: Advanced Electronic Materials, E-ISSN 2199-160X, Vol. 5, no 3, article id 1800924Article in journal (Refereed)
    Abstract [en]

    This work presents a route to fabricate micropatterned conductive structures where the conductors are monolithically integrated with nanocellulose-based paper. To fabricate conductive features, microstructures are patterned on filter papers using wax-printing, followed by vacuum filtration of carbon nanotubes (CNTs) or silver nanowires (AgNWs) dispersed in aqueous cellulose nanofibrils (CNFs). These patterns are then laminated onto a pure CNF substrate (both in gel-state) and dried to form cellulose nanopapers with integrated conductive micropatterns. Resolutions of the conductive features are shown down to 400 µm wide, 250 nm thick, and with conductivity values of 115 ± 5 S cm −1 for the CNF–CNT and 3770 ± 230 S cm −1 for the CNF–AgNW micropatterns. The nanopaper and the conductive patterns both constitute random fibrous networks, and they display similar ductility and swelling behavior in water. Thus, the integrated conductive micropatterns can withstand folding, as well as wetting cycles. This stability of the micropatterns makes them useful in various devices based on nanocellulose substrates. As an example, an electroanalytical nanopaper device that operates in wet conditions is demonstrated.

  • 27.
    Hallström, Stefan
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Grenestedt, Joakim L
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Mixed mode fracture of cracks and wedge shaped notches in expanded PVC foam1998In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 88, no 4, p. 343-358Article in journal (Refereed)
    Abstract [en]

    Fracture initiated from a sharp crack or wedge shaped notch in a homogeneous material, subjected to different loading is considered. Singularities in the stress fields at edges and vertices are discussed. A point-stress criterion is used to predict fracture for sharp cracks as well as 90° wedge notches in expanded PVC foam. The point-stress criterion is formulated in a manner allowing failure predictions in general 3D stress situations. The influence of non-singular T-stress at cracks is discussed and substantiated by experimental results.

  • 28.
    Hansson, Jonas
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Karlsson, J. Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Carlborg, Carl Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Low gas permeable and non-absorbent rubbery OSTE+ for pneumatic microvalves2014In: Proceedings of the 27th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2014), IEEE conference proceedings, 2014, p. 987-990Conference paper (Refereed)
    Abstract [en]

    In this paper we introduce a new polymer for use in microfluidic applications, based on the off-stoichiometric thiol–ene-epoxy (OSTE+) polymer system, but with rubbery properties. We characterize and benchmark the new polymer against PDMS. We demonstrate that Rubbery OSTE+: has more than 90% lower permeability to gases compared to PDMS, has little to no absorption of dissolved molecules, can be layer bonded in room temperature without the need for adhesives or plasma treatment, can be structured by standard micro-molding manufacturing, and shows similar performance as PDMS for pneumatic microvalves, albeit allowing handling of larger pressure. 

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  • 29.
    Hassanzadeh, Salman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology. Chemistry Department, School of Science, University of Tehran, Iran .
    Khoee, Sepideh
    Beheshti, Abolghasem
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Release of quercetin from micellar nanoparticles with saturated and unsaturated core forming polyesters - A combined computational and experimental study2015In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 46, p. 417-426Article in journal (Refereed)
    Abstract [en]

    Computational and experimental studies were combined to obtain new insight into the widely reported anomalous release mechanism of hydrophobic drug (quercetin) from polymeric micellar nanopartides. Saturated and unsaturated amphiphilic triblock copolymers from monomethoxy polyethylene glycol (mPEG), poly(butylene adipate) (PBA) and poly(cis-2-butene adipate) (PCBA) (mPEG-PBA-mPEG and mPEG-PCBA-mPEG) were utilized as model polymers to specify the contribution of polymer-micelle degradation and polymer-drug interactions on the observed differences in the release rates by applicable computational investigation and experimental evaluations. Monitoring the size of the micelles through the releasing process together with hydrolytic degradation studies of the core forming polymers proved that the contribution of polymer hydrolysis and micelle degradation on the observed differences in the release rates during the release time window was minimal. The compatibility between quercetin and the core forming polymer is another factor influencing the drug encapsulation and the relative release rate and it was therefore investigated theoretically (using density functional theory (DFT) at B3LYP/6-311(++)G level of theory) and experimentally (FT-IR imaging). The drug-polymer interactions in the core were shown to be much more important than the polymer and/or micelle swelling-dissociation-degradation processes under the studied conditions.

  • 30. Hauer, Bernhard
    et al.
    Engelmark Cassimjee, David Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Process for producing polyamines2009Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a process for the production of a polyamine involving the use of enzymes; in particular to a process performed in aqueous environment; to the polyamines produced by said method; as well as the use of said polyamines for manufacturing paper, for immobilizing enzymes, or for preparing pharmaceutical or cosmetical compositions. The invention also relates to a novel method for in situ regeneration of cofactors NAD(P)+.

  • 31.
    He, Qixiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Development of waterborne bio-based primers for metal application2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For the purpose of moving towards a more sustainable economy, coatings with higher bio-based carbon content and less VOCs have attracted more and more attention. In this study, waterborne primer formulations based on different alkyd resins were prepared by mixing raw materials together, and then applied with a roll applicator or an air-mix sprayer on both glassand metal substrates. The films obtained were later studied and their properties were found to be good: they presented excellent humidity corrosion resistance and high bio-based carbon content. Moreover, bio-based epoxidized linseed oil, together with four amine-based hardeners (diamine, polyamide, polyethyleneimine, and polyamine) was explored to be part of the waterborne primer systems in orderto further increase the bio-based carbon content. However, due to the intrinsic properties of the partially epoxidized linseed oil, such as low reactivity at room temperature and high immiscibility with water, the attempts of using amine-based hardeners to cure epoxidized linseed oil in a waterborne system were unsuccessful.

  • 32.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Barrier Packaging Materials2005In: Handbook of Environmental Degradation of Materials, Norwich, NY: William Andrew Inc. , 2005, p. 547-563Chapter in book (Other academic)
    Abstract [en]

    This chapter deals with the barriers in packaging materials. Plastic packaging materials offer toughness, lighter weight, and a level of design flexibility that glass and metal cannot meet. They are permeable to gases, vapors, and liquids, and this limits their use to products that do not require the highest barrier protection. Several ways to improve their barrier properties and to make them competitive with glass and metal are discussed. No other material group offers the same huge range in permeability as polymers do. The success in obtaining a packaging material with optimal barrier properties requires knowledge on all levels, from atomistic details to converting and handling properties. The chapter explains the way the introduction of new molecular groups affects the molecular rigidity, the material crystallinity, the interlayer adhesion, and the folding/sealing properties. All these parameters have an impact on the final packaging barrier properties. The important factors that determine and enhance the barrier properties are described with practical examples in packaging. The chapter also discusses the problems associated with selecting packaging materials for food.

  • 33.
    Hedman, Nathalie
    KTH, School of Chemical Science and Engineering (CHE).
    Some methods for improving the odour barrier properties of biodegradable thin plastic films for use in Peepoo toilets2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 34.
    Hernodh Svantesson, Isabelle
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Grånäs Jakobsson, Saga
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    An analysis of creating plastic material based on the microalgae Scenedesmus2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The microalgae Scenedesmus Bloom are grown in sewage environment and contains, among other things, polymers of saccharides. The polysaccharides can possibly be extracted and used for the manufacturing of plastic material. The algae have a strong cell wall, can grow fast in severe external conditions and shows good ability to capture carbon dioxide.

    This study attempts to extract polymers from the algae, which will be used to create plastic films based on the microalgae. Analyses were made to determine which method gave the best results. The extraction methods that were performed were acid hydrothermal extraction, ultrasonic extraction and a combination of both methods. Before the extraction took place, preparation of the algae was performed. The preparation consisted of grinding the algae and washing the algae with acetone. The washing methods used in this study showed to not have a big influence and was therefore considered unnecessary. After the extraction, methods as dialysis and freezedrying were performed, for purification and drying of the extracted material. Finally, plastic films were made by a mixture of the extracted material and carboxymethylcellulose sodium salt. Successful films were created from extracted material from washed algae that had undergone ultrasonic extraction and from unwashed algae that had undergone the acid hydrothermal extraction. The study showed that washed algae that had undergone ultrasonic extraction gave the best results. The created films were very brittle and without the addition of any additives, no useful applications could be found.

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  • 35.
    Hua, Geng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Johan, Franzén
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    One-pot inimer promoted ROCP synthesis of branched copolyesters using α-hydroxy-γ-butyrolactone as the branching reagent2016In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 54, no 13, p. 1908-1918Article in journal (Refereed)
    Abstract [en]

    An array of branched poly(ɛ-caprolactone)s was successfully synthesized using an one-pot inimer promoted ring-opening multibranching copolymerization (ROCP) reaction. The biorenewable, commercially available yet unexploited comonomer and initiator 2-hydroxy-γ-butyrolactone was chosen as the inimer to extend the use of 5-membered lactones to branched structures and simultaneously avoiding the typical tedious work involved in the inimer preparation. Reactions were carried out both in bulk and in solution using stannous octoate (Sn(Oct)2) as the catalyst. Polymerizations with inimer equivalents varying from 0.01 to 0.2 were conducted which resulted in polymers with a degree of branching ranging from 0.049 to 0.124. Detailed ROCP kinetics of different inimer systems were compared to illustrate the branch formation mechanism. The resulting polymer structures were confirmed by 1H, 13C, and 1H-13C HSQC NMR and SEC (RI detector and triple detectors). The thermal properties of polymers with different degree of branching were investigated by DSC, confirming the branch formation. Through this work, we have extended the current use of the non-homopolymerizable γ-butyrolactone to the branched polymers and thoroughly examined its behaviors in ROCP.

  • 36.
    Hua, Geng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Exploiting Ring-Opening Aminolysis–Condensation as a Polymerization Pathway to Structurally Diverse Biobased Polyamides2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    A pathway to biobased polyamides (PAs) via ring-opening aminolysis–condensation (ROAC) under benign conditions with diverse structure was designed. Ethylene brassylate (EB), a plant oil-derived cyclic dilactone, was used in combination with an array of diamines of diverse chemical structure, and ring-opening of the cyclic dilactone EB was revealed as a driving force for the reaction. The ROAC reactions were adjusted, and reaction conditions of 100 °C under atmospheric pressure using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a catalyst for 24 h were optimal. The structures of the polyamides were confirmed by mass spectroscopy, FTIR, and NMR, and the PAs had viscosity average molecular weights (Mη) of ∼5–8 kDa. Glassy or semicrystalline PAs with glass transition temperatures between 48 and 55 °C, melting temperatures of 120–200 °C for the semicrystalline PAs, and thermal stabilities above 400 °C were obtained and were comparable to the existing PAs with similar structures. As a proof-of-concept of their usage, one of the PAs was shown to form fibers by electrospinning and films by melt pressing. Compared to conventional methods for PA synthesis, the ROAC route portrayed a reaction temperature at least 60–80 °C lower, could be readily carried out without a low-pressure environment, and eliminated the use of solvents and toxic chemicals. Together with the plant oil-derived monomer (EB), the ROAC route provided a sustainable alternative to design biobased PAs.

  • 37.
    Huang, Tianxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Hydrophobization of cellulose for bio-based materials2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    As a main structural component of plants, cellulose is naturally abundant and widely distributed on earth. Although the chemical formula of cellulose was determined in 1838, human beings have been using cellulose to produce daily necessities, such as textiles and paper, for thousands of years. In modern society, the applications of cellulose have expanded considerably as the understanding of the chemistry of cellulose has increased, and researchers have been able to alter the structure of cellulose to obtain new properties to meet new requirements. With this strategy of structure alteration, this work demonstrated new methods of hydrophobization of cellulose to prepare emerging materials with new or improved properties.Cellulose is commonly used for reinforcement in composites. In this study, a new type of microcellulose, cellulose oxalate (COX), was used to prepare polymeric composites. COX was first hydrophobized by maleated polypropylene (MAPP) or oleic acid to obtain better compatibility with the hydrophobic matrix of polypropylene (PP). It was found that a composite consisting of 60% PP and 40% MAPP-hydrophobized COX had a 16% higher tensile strength and a 106% higher Young’s modulus than neat PP. When oleic acid was used to hydrophobize COX, it was possible to avoid using toxic catalysts to complete the esterification between COX and oleic acid. This fact makes the process environmentally friendly.Similarly, considering environmental protection, natural compounds were used to prepare hydrophobic cellulosic textiles. Betulin, a kind of wood extract and by-product in the forestry industry, was used to modify the wettability of cellulosic textiles. The textiles underwent a dip-dry-cure process from a betulin solution had a static water contact angle (SWCA) of 153°. Textiles coated by a betulin-based film exhibited a water-repellency score of 80 according to a standard test from the American Association of Textile Chemists and Colorists (AATCC). Betulin-grafted cotton textiles were also prepared, and such textiles showed not only hydrophobic properties (SWCA up to 136°) but also antibacterial properties, with bacterial removal of more than 99%.This thesis proposes that hydrophobized cellulosic materials can be used in various fields, both related and unrelated to waterproof applications. Furthermore, by-products in the forestry industry, such as betulin and oleic acid, are advocated for use because of their biodegradability and value.

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  • 38.
    Huas, Hugo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jérome, Titouan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Artificial Spider Web: Selection of Polymeric Materials for Special Effects Applications2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Artificial  spider  webs  are  a  challenge  for  the  special  effects  companies.   The natural  spider webs  are  displaying  incredible  mechanical  properties  combined with  a  low  density  and  a  high stickiness making them hard to reproduce. Throughout this project the aim is to produce artificial spider  webs  using  a specific  manufacturing  method,  pouring  a  mix  of  polymer  and  Naphtha  oil into  water  to  form  the  webs.   This  method  was  used  in  previous  cinematic applications  giving outstanding results for the artificial spider webs.  Unfortunately, due to the loss of it, the specific parameters,  tools and raw materials have to be found.  A material selection is given leading to a specific choice of thermoplastic polymers.  The selected material are then tested manually so they can be listed depending on the results obtained.  Finally, the most promising material seems to be TPU, thermoplastic polyurethane;  thanks to its excellent mechanical properties and good visual aspect.

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  • 39.
    Ibn Yaich, Anas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Strategies for Renewable Barriers with Enhanced Performance2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Forest biomass is expected to play an increasingly important role in tomorrow´s global bio-economy as one of the main renewable sources of materials, chemicals and energy. In the framework of the biorefinery concept, the forestry industry is looking for new processes to utilize several fractions in the biomass (cellulose, hemicelluloses, lignin etc.), thereby generating value-added by-products, an economically sustainable process, and new market opportunities. The work presented in this thesis aims to develop oxygen barrier films and coatings based on the hemicelluloses-rich biorefinery fraction, referred to as wood hydrolysate (WH). These WHs were obtained from the aqueous process liquor after the hydrothermal treatment of hardwood. The WH-based films and coatings are intended to meet the increasing demand of bio-based and biodegradable barrier materials in multi-layered laminates for the food-packaging sector. This work has employed four strategies to provide control and enhancement of the mechanical and barrier properties of WH: I) a selective choice of up-grading pre-treatments of the WH aqueous liquor, II) the incorporation of layer silicates into the barrier formulation, III) chain-extension of the hemicellulose chains present in the WH via reductive amination, and IV) the development of wood hydrolysate polyelectrolyte complexes (PEC) with quaternized cellulose (QC). It has been demonstrated that the crude WH, with almost no upgrading pre-treatment, produced coatings with the best performance in terms of low oxygen permeability. Furthermore, the addition of naturally occurring layered silicates into the WH-based film formulations led to a decrease in water vapor permeability, and a considerably lower oxygen permeability at 80% relative humidity. Moreover, the chain-extension approach was shown to significantly enhance the formability and mechanical performance of WH-based films, making it possible to produce cohesive films with a higher proportion of WH, 70–85% (w/w) and to reduce the content of co-components in the films. The WH/QC-PEC-based films exhibited by far the best tensile properties, better than those previously obtained with carboxymethyl cellulose as a co-component in an equal amount, with a tensile strain-at-break as high as 7 %.

  • 40.
    Ibn Yaich, Anas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Wood hydrolysate Barriers2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wood hemicellulose is an abundant but fairly unexploited renewable feedstock. Recent studies have shown that hemicelluloses have a large potential for use in the food packaging industry as a sustainable alternative to the conventional oxygen-barrier materials used today. Such hemicelluloses are the main components of wood hydrolysates (WH), which are released in large quantities in many forestry process side streams. Recovering these hemicellulose-rich WH fractions and turning them into food packaging materials would be beneficial from both, an environmental and an economic point of view. However, in the development of packaging materials for large-scale applications, the high production costs to obtain the highly purified hemicellulose and their high moisture sensitivity are considered to be the two main limiting factors.In this study, a selective choice of the upgrading conditions during the recovery of WH and the incorporation of layered silicate particles in WH-based films and coating formulations are used as tools to control and tailor the barrier and tensile performances of the materials, enabling the design of renewable oxygen-barrier materials that are cost-effective and with improved properties. The WH originated from the aqueous liquor from hardwood hydrothermal treatment and upgraded according to one of three alternative routes (ultrafiltration, ultrafiltration followed by diafiltration, and ethanol precipitation) resulting in hemicellulose-rich fractions with different structures, compositions, and properties, which in turn resulted in different performances in terms of mechanical and oxygen-permeability properties. WH in its crudest form gave rise to coatings with the best oxygen-barrier performance, higher than the oxygen-barrier performance of pure hemicellulose coatings. The addition of montmorillonite or talc layered silicates as mineral additives in the WH-based films resulted in better water-vapor-barrier properties, and considerably improved oxygen barrier performance at a relative humidity as high as 80 %. The application of the WH-based films was therefore extended to a wider range of relative humidity conditions.

  • 41.
    Ibn Yaich, Anas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Barriers from wood hydrolysate/quaternized cellulose polyelectrolyte complexes2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 3, p. 1977-1991Article in journal (Refereed)
    Abstract [en]

    Biobased polyelectrolyte complexes (PECs) were prepared by mixing negatively charged O-acetyl-4-O-methylglucuronoxylan-rich wood hydrolysate (WH) and positively charged quaternized cellulose (QC) in aqueous solution. The WH was obtained as an aqueous process liquor of the hydrothermal treatment of birch wood chips and partially upgraded by membrane filtration and dialysis. Three QC derivatives with different degrees of quaternization were synthesized, characterized in terms of molecular weight, charge density, crystallinity and solubility, and utilized for PEC production. The WH/QC PECs were designed to form free-standing films with high oxygen barrier performance and good mechanical integrity. The impact of the QC degree of quaternization on the oxygen permeability at both 50 and 80 % relative humidity, water vapor permeability and tensile properties was investigated. Films with a tensile strain-to-break as high as 7 % and an oxygen permeability as low as 1.3 (cm(3) mu m)/(m(2) - day kPa) at 80 % relative humidity were achieved.

  • 42.
    Jain, Karishma
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wang, Zhen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Garma, Leonardo D.
    Karolinska Inst, Med Biochem & Biophys, Stockholm, Sweden..
    Engel, Emile
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Ciftci, Göksu Cinar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Fager, Cecilia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    3D printable composites of modified cellulose fibers and conductive polymers and their use in wearable electronics2023In: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 30, article id 101703Article in journal (Refereed)
    Abstract [en]

    There are many bioelectronic applications where the additive manufacturing of conductive polymers may be of use. This method is cheap, versatile and allows fine control over the design of wearable electronic devices. Nanocellulose has been widely used as a rheology modifier in bio-based inks that are used to print electrical components and devices. However, the preparation of nanocellulose is energy and time consuming. In this work an easy-to-prepare, 3D-printable, conductive bio-ink; based on modified cellulose fibers and poly(3,4-ethylene dioxythiophene) poly(styrene sulfonate) (PEDOT:PSS), is presented. The ink shows excellent printability, the printed samples are wet stable and show excellent electrical and electrochemical performance. The printed structures have a conductivity of 30 S/cm, high tensile strains (>40%), and specific capacitances of 211 F/g; even though the PEDOT:PSS only accounts for 40 wt% of the total ink composition. Scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS), and Raman spectroscopy data show that the modified cellulose fibers induce conformational changes and phase separation in PEDOT:PSS. It is also demonstrated that wearable supercapacitors and biopotential-monitoring devices can be prepared using this ink.

  • 43.
    Ji, Qinglei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Sustainable Production Systems. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Zhao, Chun
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. Beijing Information Science and Technology University.
    Chen, Mo
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Sustainable Production Systems.
    Wang, Xi Vincent
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Feng, Lei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Sustainable Production Systems.
    A Flexible 4D Printing Service Platform for Smart Manufacturing2020In: Swedish Production Symposium, 2020Conference paper (Refereed)
    Abstract [en]

    With the extensive application of 3D printing (3DP) in smartmanufacturing, 4D printing (4DP), which enhances 3D printed objects with shapemorphing ability by using smart materials, has shown significant industrial potentialand attracted tremendous attention. One key concern of 4DP is how to effectivelyand quickly meet different production and application requirements considering thecomplexity of materials and diversity of stimulus methods. In order to provide ageneral research platform for 4DP researchers, a flexible 4DP service platform isproposed. Components and modules for building 4DP and test systems are modeledand virtualized to form the different resources. These resources are then integratedvirtually or physically to provide some basic functions such as a 3D displacementstage or a visual monitoring system. According to different 4DP requirements, thesefunctions are then encapsulated into services to serve different research. Theplatform enables a variety of 4DP applications in smart manufacturing environmentssuch as 4D printed magnetic medical robots, test platform for studying the 4DPresponse, etc. A case study on designing a ferromagnetic 4DP platform based on theservice platform is performed to prove the feasibility of the method.

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  • 44.
    Johnsson, Nathalie
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Steuer, Fredrik
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bioplastic material from microalgae: Extraction of starch and PHA from microalgae to create a bioplastic material2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Microalgae used in sewers to capture CO2 eventually turns into waste material. Through the use oftheir biomass, the waste algae can be given a new purpose. In this study attempts to extract starch or PHA from three different algae; Calothrix Scytonemicola, Scenedesmus Almeriensis and Neochloris Oleoabundans, were made. We also attempted to create a bio-based plastic material.

    Both Scenedesmus Almeriensis and Neochloris Oleoabundans are starch rich microalga. By washing with acetone, cryo grinding, use of ultrasonic homogenizer and dialysis, starch was likely extracted successfully. The extracted material and the plasticiser Carboxymethyl Cellulose (CMC) was used to cast plastic film. The cast film was very thin and brittle; perhaps by using different plasticisers or additives a more usable bio-based plastic material can be created.

    The PHA rich algae Calothrix Scytonemicola was used to extract PHA. The algae was washed with acetone, cryo grinded and then mixed with Sodium Hypochlorite(aq) and deionised water to extract the desired PHA. Due to a shortage of algae very small amounts of material could be extracted. Therefore, the casting of a plastic film was performed with commercial PH3B, which is a type of PHA. Three attempts were conducted. The first one with only chloroform, the second one with CMC and chloroform and the last one with Sucrose Octaacetate and chloroform. The film with Sucrose Octaacetate gave the best plastic material in regards to mechanical properties.

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    Bioplastic material from microalgae
  • 45.
    Juntikka, Rickard
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Selection of energy absorbing materials for automotive head impact countermeasures2004In: Cellular polymers, ISSN 0262-4893, E-ISSN 1478-2421, Vol. 23, no 5, p. 263-297Article in journal (Refereed)
    Abstract [en]

    Material candidates for energy absorption in head impact countermeasures for automotive applications are evaluated using both quasi-static and dynamic test methods. Ranking of different materials turns out to be difficult since the mechanical response of a material could vary considerably with temperature, especially for polymers. Twenty-eight selected materials, including foams, honeycombs and balsa wood are tested and evaluated. The materials are subjected to a sequence of tests in order to thin out the array systematically. Quasi-static uni-axial compression is used for initial mapping of the selected materials, followed by quasi-static shear and dynamic uni-axial compression. The quasi-static test results show that balsa wood has by far the highest energy absorption capacity per unit weight but the yield strength is too high to make it suitable for the current application. The subsequent dynamic compression tests are performed for strain rates between 56 s(-1) and 120 s(-1) (impact velocities between 1.4 and 3 m/s) and temperatures in the range -20 - 60 degreesC. The test results emphasize the necessity of including both strain rate and temperature dependency to acquire reliable results from computer simulations of the selected materials.

  • 46.
    Juntikka, Rickard
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Weight-balanced drop test method for characterization of dynamic properties of cellular materials2004In: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 30, no 5, p. 541-554Article in journal (Refereed)
    Abstract [en]

    A novel weight-balanced drop rig used to evaluate the response of cellular materials subject to dynamic compression is presented. The testing method utilizes approximately constant velocity throughout the major part of the compression phase and the results compare well with results from other methods, reported in the literature. The repetitiveness is excellent, the rig is simple and the results are easily extracted. The applicability of the method for determination of elastic modulus is however limited to materials with relatively low stiffness. Accurate modulus measurements for stiff materials at high strain-rates require a very rigid and lightweight test set-up.

  • 47. Jönsson, C.
    et al.
    Wei, R.
    Biundo, Antonino
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Science for Life Laboratory, Tomtebodavägen 23, Box 1031 171 21 Solna, Stockholm, Sweden.
    Landberg, J.
    Schwarz Bour, L.
    Pezzotti, F.
    Toca, A.
    M. Jacques, L.
    Bornscheuer, U. T.
    Syrén, Per-Olof
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles2021In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 14, no 19, p. 4028-4040Article in journal (Refereed)
    Abstract [en]

    Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported. In contrast, by analyzing market data and emerging trends for synthetic fibers in the textile industry, in combination with numbers from used garment collection and sorting plants, it was shown that the use of difficult-to-recycle blended materials is rapidly growing. If the lack of recycling technology and production trend for fiber blends remains, a volume of more than 3400 Mt of waste will have been accumulated by 2030. This work highlights the urgent need to transform the textile industry from a biocatalytic perspective.

  • 48.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Effective visco-elastic models of tough, doubly cross-linked, single-network polyvinyl alcohol (PVA) hydrogels: Additively separable fractional derivative-based models for chemical and physical cross-links2020In: Continuum Mechanics and Thermodynamics, ISSN 0935-1175, E-ISSN 1432-0959Article in journal (Refereed)
    Abstract [en]

    An effective fractional derivative-based visco-elastic model of tough, doubly cross-linked, single-network polyvinyl alcohol (PVA) hydrogels, embodying both chemical and physical cross-links, is developed using a Mittag–Leffler relaxation function of order 1/2 while applying only three material parameters that are physically quantifiable, namely frequency for maximum loss modulus, equilibrium elastic modulus and relaxation intensity. The resulting 3-parameter shear modulus model is possible to additively split into chemical and physical parts; the split being the study focus. Physical explanations of the visco-elastic low-, mid- and high-frequency range properties, and their transitions between the frequency ranges, are given mainly in terms of the permanent chemical cross-links and the distinct adhesion–deadhesion processes of the transient physical cross-links. The latter are running from an associated Rouse mode low-frequency behaviour through a maximum adhesion–deadhesion dissipation and to an elastic, fully active cross-link high-frequency behaviour, while the former are displaying essentially an elastic, fully active cross-link behaviour throughout the frequency range. The developed model covers the full frequency range while matching measurements results remarkably well. Furthermore, the model is refined into a 4-parameter model by additively including an Abel relaxation function of order 1/2 to take into account the superimposed Rouse-type behaviour found in the measurements of the chemical cross-links in addition to their dominating elastic response, with the fourth parameter being a chemical Rouse stress intensity factor. The simple, effective visco-elastic models are suitable in predicting the mechanical properties of tough, doubly cross-linked, single-network PVA hydrogels with application potentials in tissue and noise abatement engineering.

  • 49.
    Karlsson, J. Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Pardon, Gaspard
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vastesson, Alexander
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Supekar, Omkar
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Carlborg, Carl Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Brandner, Brigit
    SP Technical Research Institute of Sweden.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Off-Stoichiometry Improves Photostructuring of Thiol-Enes Through Diffusion-Induced Monomer Depletion2016In: Microsystems and Nanoengineering, ISSN 2055-7434, Vol. 2, article id 15043Article in journal (Refereed)
    Abstract [en]

    Thiol-enes are a group of alternating copolymers with highly ordered networks used in a wide range of applications. Here, “click” chemistry photostructuring in off-stoichiometric thiol-enes is shown to induce microscale polymeric compositional gradients due to species diffusion between non-illuminated and illuminated regions, creating two narrow zones with distinct composition on either side of the photomask feature boundary: a densely cross-linked zone in the illuminated region and a zone with an unpolymerized highly off-stoichiometric monomer composition in the non-illuminated region. By the use of confocal Raman microscopy, it is here explained how species diffusion causes such intricate compositional gradients in the polymer, and how off-stoichiometry results in improved image transfer accuracy in thiol-ene photostructuring. Furthermore, increasing the functional group off-stoichiometry and decreasing photomask feature size is shown to amplify the induced gradients, which potentially leads to a new methodology for microstructuring.

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  • 50.
    Karlsson, Mattias E.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Fundamentals of Polyethylene Composites for HVDC Cable Insulation – Interfaces and Charge Carriers2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Power transmission over long distances by using high voltage direct current (HVDC) cables is important for the transition from fossil energy to using renewable energy sources, e.g. wind, solar and water. Higher operating voltages enable longer transmission lines but better insulation materials with a much lower conductivity than today´s crosslinked polyethylene (PE) are required to reach the goal of 1 MV by 2030. Nanocomposites consisting of small fractions of metal oxide nanoparticles in PE are promising insulation materials, showing ca. 100 times lower conductivity. The reasons for the better insulating properties are however not fully understood.

    The properties of PE and inorganic nanoparticles were studied in this project to evaluate the influence of different material parameters on the conductivity of the cable insulation material. For pristine PE, the polymer morphology and oxidation were found to have a significant impact on the conductivity. For PE nanocomposites, the particle/polymer interface was shown to adsorb polar molecules, which are present in PE cable insulation. A suggested hypothesis is that the adsorption on particle surfaces results in cleaning of the bulk polymer from impurities, which in turn contributes to decreased nanocomposite conductivity. Since the particle interface is believed to be decisive for the nanocomposite properties, the role of particle terminations was investigated in detail. Oxygen dominated particle terminations resulted in 2 times higher composite conductivity than with zinc dominated surfaces, while fully oxygen covered surfaces showed 10 times higher conductivity. Composite systems with micro-sized particles allowed for evaluating parameters independently, which is not possible for nanocomposites. Terminations of ‘PE-like’ hydrocarbon chains lowered the conductivity and these trends could also be transferred to similar zinc oxide nanocomposite systems.

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