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  • 1.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Ji, Guangchao
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Björlin, Anders
    Kiwok AB.
    Östlund, Anders
    Kiwok AB.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Textile-Electronic Integration in Wearable Measurement Garments for Pervasive Healthcare Monitoring2015Konferansepaper (Annet vitenskapelig)
  • 2.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Guangchao, Li
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås.
    A Knitted Garment using Intarsia Technique for Heart Rate Variability Biofeedback: Evaluation of Initial Prototype.2015Konferansepaper (Annet vitenskapelig)
  • 3.
    Atarijabarzadeh, Sevil
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Biofilm adhesion on silicone materials2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    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.

  • 4.
    Austrell, Per-Erik
    et al.
    Division of Structural Mechanics, Lund Institute of Technology.
    Kari, LeifKTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Constitutive Models for Rubber IV: proceedings of the 4th European Conference for Constitutive Models for Rubber, ECCMR 2005, Stockholm, Sweden, 27-29 June 20052005Collection/Antologi (Fagfellevurdert)
    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.

  • 5.
    Becerra, Marley
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Friberg, Andreas
    ABB Corporate Research, Västerås.
    Arc jets blown by outgassing polymers in air2014Inngår i: Proceedings of the 20th International Conference on Gas Discharges and Their Applications GD2014, GD2014 , 2014, s. 1-4Konferansepaper (Fagfellevurdert)
    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. 

  • 6.
    Bladholm, Viktor
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Organic Fillers for Solid Rocket Fuel2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Idag är de vanligaste använda raketerna flytande-bränsle- och fast-bränsle- raketer. Flytande-bränsle-raketer har fördelen att det kan manövreras men de har en komplex design och problem med förvaring. Fast-bränsle-raketer har en enkel design och kan förvaras men de har en miljöpåverkan och bränslet kan vara svårhanterligt. En tredje typ av raketer, hybridraketer, kan kombinera enkelheten från fasta-bränsle-raketer med manövreringsbarheten från vätske-bränsle-raketer. Trots fördelarna med hybridraketer används de inte på grund av att bränslet har låg regressionshastighet och låg densitet. Organiska additiv har visat sig förbättra dessa egenskaper. 50 organiska additiv granskades med avseende på deras specifika impuls, densitet, kostnad och användarvänlighet. De mest lovande organiska additiven utvärderades sedan experimentellt. Termogravimetrisk analys (TGA), isotermviktförlust, kompatibilitet och differentiell svepkalorimetri (DSC) användes. Resultaten indikerar att hexamin, fluorene, anthracene och 1,4-dicyanobenzene har mest potential att förbättra bränslet i hybridraketer.

  • 7.
    Brumer, Harry
    et al.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Rutland, Mark
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Sinnott, M. L.
    Teeri, Tuula T.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Zhou, Qi
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Cross-Linking Involving a Polymeric Carbohydrate Material2005Patent (Annet (populærvitenskap, debatt, mm))
    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.

  • 8.
    Chen, Fei
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Chitosan and chitosan/wheat gluten blends: properties of extrudates, solid films and bio-foams2015Doktoravhandling, med artikler (Annet vitenskapelig)
    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.  

  • 9.
    Chen, Fei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gällstedt, Mikael
    Olsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    A Novel Chitosan/Wheat Gluten Biofoam Fabricated by Mixing and Vacuum-dryingManuskript (preprint) (Annet vitenskapelig)
  • 10.
    Chen, Fei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gällstedt, Mikael
    Olsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Unusual Effects of Monocarboxylic Acids on The Structure and on The Transport and Mechanical Properties of Chitosan Films2015Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 132, s. 419-429Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11.
    Claesson, Per M.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. RISE.
    Dobryden, Illia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    He, Yunjuan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Li, Gen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Surface Nanomechanics of Coatings and Hydrogels2019Inngår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2019, nr 1Konferansepaper (Fagfellevurdert)
    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.

  • 12.
    Cuenca, Jacques
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Van der Kelen, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    A general methodology for inverse estimation of the elastic and anelastic properties of anisotropic open-cell porous materials-with application to a melamine foam2014Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, nr 8, s. 084904-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 13.
    Decrop, Deborah
    et al.
    KU Leuven, Belgium.
    Pardon, Gaspard
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Kokalj, Tadej
    KU Leuven, Belgium.
    Robert, Puers
    KU Leuven, Belgium.
    Haraldsson, Tommy
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Lammertyn, Jeroen
    KU Leuven, Belgium.
    van der Wijngaart, Wouter
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer2015Inngår i: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015), IEEE , 2015Konferansepaper (Fagfellevurdert)
    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.

  • 14.
    Feng, Zhaoxuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    From Polysaccharides to Functional Materials for Trace Pharmaceutical Adsorption2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Fulltekst tilgjengelig fra 2020-04-20 12:12
  • 15.
    Glad, David
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    A natural-based absorbent polymer based on potato protein: Functionalized via dry acylation with high scalability2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    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. 

  • 16.
    Grenestedt, Joakim L
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Hallström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Kuttenkeuler, Jakob
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    On cracks emanating from wedges in expanded PVC foam1996Inngår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 54, nr 4, s. 445-456Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 17.
    Hajian, Alireza
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Fu, Qiliang
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Recyclable and superelastic aerogels based on carbon nanotubes and carboxymethyl cellulose2018Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 159, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 18.
    Hajian, Alireza
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wang, Zhen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Berglund, Lars. A
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hamedi, Mahiar M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Cellulose Nanopaper with Monolithically Integrated Conductive Micropatterns2019Inngår i: Advanced Electronic Materials, ISSN 2199-160X, Vol. 5, nr 3, artikkel-id 1800924Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 19.
    Hallström, Stefan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Grenestedt, Joakim L
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Mixed mode fracture of cracks and wedge shaped notches in expanded PVC foam1998Inngår i: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 88, nr 4, s. 343-358Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 20.
    Hansson, Jonas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Karlsson, J. Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Carlborg, Carl Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    van der Wijngaart, Wouter
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Haraldsson, Tommy
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Low gas permeable and non-absorbent rubbery OSTE+ for pneumatic microvalves2014Inngår i: Proceedings of the 27th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2014), IEEE conference proceedings, 2014, s. 987-990Konferansepaper (Fagfellevurdert)
    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. 

  • 21.
    Hassanzadeh, Salman
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi. Chemistry Department, School of Science, University of Tehran, Iran .
    Khoee, Sepideh
    Beheshti, Abolghasem
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Release of quercetin from micellar nanoparticles with saturated and unsaturated core forming polyesters - A combined computational and experimental study2015Inngår i: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 46, s. 417-426Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 22. Hauer, Bernhard
    et al.
    Engelmark Cassimjee, David Karim
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi (stängd 20130101).
    Process for producing polyamines2009Patent (Annet (populærvitenskap, debatt, mm))
    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)+.

  • 23.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Barrier Packaging Materials2005Inngår i: Handbook of Environmental Degradation of Materials, Norwich, NY: William Andrew Inc. , 2005, s. 547-563Kapittel i bok, del av antologi (Annet vitenskapelig)
    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.

  • 24.
    Hedman, Nathalie
    KTH, Skolan för kemivetenskap (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 poäng / 30 hpOppgave
  • 25.
    Hernodh Svantesson, Isabelle
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Grånäs Jakobsson, Saga
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    An analysis of creating plastic material based on the microalgae Scenedesmus2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    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.

  • 26.
    Hua, Geng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Johan, Franzén
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    One-pot inimer promoted ROCP synthesis of branched copolyesters using α-hydroxy-γ-butyrolactone as the branching reagent2016Inngår i: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 54, nr 13, s. 1908-1918Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 27.
    Hua, Geng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Exploiting Ring-Opening Aminolysis–Condensation as a Polymerization Pathway to Structurally Diverse Biobased Polyamides2018Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 28.
    Ibn Yaich, Anas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Strategies for Renewable Barriers with Enhanced Performance2015Doktoravhandling, med artikler (Annet vitenskapelig)
    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 %.

  • 29.
    Ibn Yaich, Anas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Wood hydrolysate Barriers2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    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.

  • 30.
    Ibn Yaich, Anas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Barriers from wood hydrolysate/quaternized cellulose polyelectrolyte complexes2015Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 3, s. 1977-1991Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 31.
    Johnsson, Nathalie
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Steuer, Fredrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Bioplastic material from microalgae: Extraction of starch and PHA from microalgae to create a bioplastic material2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    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.

  • 32.
    Juntikka, Rickard
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Hallström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Selection of energy absorbing materials for automotive head impact countermeasures2004Inngår i: Cellular polymers, ISSN 0262-4893, E-ISSN 1478-2421, Vol. 23, nr 5, s. 263-297Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 33.
    Juntikka, Rickard
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Hallström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Weight-balanced drop test method for characterization of dynamic properties of cellular materials2004Inngår i: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 30, nr 5, s. 541-554Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 34.
    Karlsson, J. Mikael
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Pardon, Gaspard
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Vastesson, Alexander
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Supekar, Omkar
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Carlborg, Carl Fredrik
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Brandner, Brigit
    SP Technical Research Institute of Sweden.
    van der Wijngaart, Wouter
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Haraldsson, Tommy
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Off-Stoichiometry Improves Photostructuring of Thiol-Enes Through Diffusion-Induced Monomer Depletion2016Inngår i: Microsystems and Nanoengineering, ISSN 2055-7434, Vol. 2, artikkel-id 15043Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 35.
    Kharazmi, Parastou
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Hållbara byggnader.
    Monitoring the gelation time and curing process of a reinforced polyester lining-original data2019Dataset
    Abstract [en]

    Polymer linings used in sewer rehabilitation technologies are expected to cure fast in order for the renewed line to return to the service quickly and with minimum disruption.  This dataset includes the original data obtained from the thermal analyses of a reinforced polyester composite used as pipe lining, including studying gelation, enthalpy and curing process for a better understanding of the material's curing behaviour after application in the field. 

    Fulltekst tilgjengelig fra 2021-01-01 12:58
  • 36.
    Kilegran, Linnea
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Rendén, Gabriella
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    The Effect of Olive Pomace in a PLA Matrix: Investigation of Mechanical Properties, Thermal Properties, Water Absorption Ability and Morphology2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This study was performed to see further usages for the by product, olive pomace, from the olive oil industry. The olive pomace was used as a filler in a Polylactic acid, PLA, matrix with different percentages. The purpose with the study was to see if the olive pomace enhanced the different properties of PLA. The properties which were investigated were the following: the mechanical properties, the thermal properties, the morphology and the amount of water absorbed.

    Several different methods were used to conduct the study, to investigate the mechanical properties the INSTRON tensile testing machine was used. To investigate the thermal properties two different methods were used, the Differential Scanning Calorimetry, DSC, and the Thermogravimetric Analysis, TGA. The morphology was studied in the Scanning Electron Microscopy, SEM, and the water absorption testing was performed through placing the samples in water for different amounts of time.

    The obtained results varied with the amount of olive pomace used in the PLA matrix. Adding the 10 wt% olive pomace to the PLA matrix showed enhanced properties for the tensile testing while adding 5 wt% olive pomace showed a decrease in the tensile properties. The DSC showed close to unchanged properties with the different compositions while the TGA showed more thermal resistant properties with the olive pomace compositions. As seen with the SEM analysis, adding the olive pomace changed the structure of the material. The amount of water absorbed increased with increasing amount of olive pomace used in the PLA matrix.

    Based on the results further research was recommended to expand and obtain more reliable results.

  • 37.
    Leygraf, Christopher
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Tidblad, J.
    Graedel, T.
    Atmospheric Corrosion: Second Edition2016Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Presents a comprehensive look at atmospheric corrosion, combining expertise in corrosion science and atmospheric chemistry Is an invaluable resource for corrosion scientists, corrosion engineers, and anyone interested in the theory and application of Atmospheric Corrosion Updates and expands topics covered to include, international exposure programs and the environmental effects of atmospheric corrosion Covers basic principles and theory of atmospheric corrosion chemistry as well as corrosion mechanisms in controlled and uncontrolled environments Details degradation of materials in architectural and structural applications, electronic devices, and cultural artifacts Includes appendices with data on specific materials, experimental techniques, atmospheric species.

  • 38.
    Lindberg, Elin
    KTH, Skolan för kemivetenskap (CHE).
    Non-woven textilier från träfibrer genom papperstillverkningsmetoder2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Idag är den största delen av textilierna antingen olje-(60 %) eller bomullsbaserade (30 %). Det är enbart en liten del som är baserade på träfibrer. Ett ökande behov av förnyelsebara textilier föreligger. Samtidigt är ett minskade pappersbehov en drivkraft till att använda de existerande pappersmaskinerna till att tillverka icke vävda textilliknande material. Till skillnad från vävda material kan materialet tillverkas direkt istället för att först tillverka trådar från fibrer. Möjligheter att ta fram textillika material av cellulosafibrer undersöktes. Dynamiska ark gjorda av en blandning av barrmassa och en blandning av barr- och lövmassa med 0, 55 och 70 vikt% polymjölksyra, PLA, tillverkades. Arken pressades ihop två och två med ett mellanlager av Expancel mikrosfärer och bindemedel. Mowilith DM 105 och Primal LT-2949 Emulsion

    användes som bindemedel. En jämförelse gjordes med ark med enbart bindemedel som mellanlager.

     

    En subjektiv utvärdering av vilket förhållande mellan Expancel mikrosfärer och bindemedel som var bäst lämpad gjordes. För utvärderingen ytbehandlades ett standard papper med 70 vikt% PLA. Den sats med högst koncentration av Expancel mikrosfärer som band bra till bindemedelet valdes. Draghållfastheten testades genom dragprovning enligt ISO 1924-2:1994 men med endast

    5 prover istället för 10.  Dragprovningen visade att tillsatsen av Expancel mikrosfärer ökade töjningen hos materialet. Materialen med högst koncentration av PLA gav den mjukaste känslan men också lägst styrka.

  • 39.
    Linde, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Polymeric materials in nuclear power plants: Lifetime prediction, condition monitoring and simulation of ageing2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Nuclear power plants generate a significant part of the world’s electrical power consumption. However, many plants are nearing the end of their designed lifetime, and to extend the lifetime it is important to verify that every component can withstand the added service time. This includes polymeric materials, which become brittle with time. By predicting their lifetime and monitoring their condition, unnecessary downtime of the plant can be avoided, and secure operation can be ensured. The lifetime can be predicted by extrapolating results from accelerated ageing to service conditions, or by simulation of the degradation process.

    In this study, lifetime predictions through extrapolation were performed on samples of a polyvinyl chloride (PVC) core insulation and an acrylonitrile butadiene rubber (NBR) membrane, which were thermally aged in air. The lifetime of the PVC cable was predicted using Arrhenius extrapolation, and using a method based on Langmuir, Clausius-Clapeyron, and Kirchhoff’s equations.

    The lifetime of the NBR membrane was predicted using extrapolation in the temperature domain using an Arrhenius approach coupled with an extrapolation in pressure-domain, yielding realistic lifetimes.

    Two cable insulations, one made from crosslinked polyethylene (XLPE) and the other from ethylene propylene rubber (EPR) were aged under the simultaneous effect of elevated temperature and γ-radiation investigated using several condition monitoring techniques. In particular, two non-destructive techniques, dielectric spectroscopy and nuclear magnetic resonance, showed promising results be developed and used in situ.

    Finally, a computer model simulating the diffusion and consumption of oxygen in XLPE was developed, based on assumptions that diffusion, consumption and solubility were dependent on the total degree of oxidation. The model showed promise for further development.

  • 40.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Nilsson, Fritjof
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Modelling of oxygen diffusion and consumption in an XLPE cableinsulation for nuclear power applications using an oxidationdependentdiffusion-reaction approachManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The oxidation profile of an XLPE conductor insulation after accelerated ageing atdifferent temperature/dose-rate combinations was assessed through infrared spectroscopy, tostudy heterogeneous oxidation in the samples. These profiles showed clear drops in oxidationdegree towards the centre of the cable, to such an extent that more than half of the thicknesswas essentially not oxidized. The oxygen diffusion and consumption was then modelledthrough computer simulations to obtain the diffusion coefficient and reaction rate, includingtheir possible dependencies on the oxidation degree. The model was based on the assumptionthat diffusion and consumption rates, and solubility of oxygen in polyethylene weredependent on the degree of oxidation relative to a maximum degree of oxidation. Good fitswith experimental data were obtained, and the model could be applied to data from literaturewith promising results.

  • 41.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Verardi, Luca
    University of Bologna.
    Pourmand, Payam
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Davide, Fabiani
    University of Bologna.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Non-destructive condition monitoring of aged ethylene-propylenecopolymer cable insulation samples using dielectric spectroscopy and NMR spectroscopyManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The causes of changes in dielectric response as a result of thermal and irradiative ageingof a cable insulation of ethylene propylene copolymer rubber containing 38 wt.% filler wereinvestigated. Samples were aged in three different combinations of irradiation dose rate andtemperature, 0.42 kGy h–1 at 85 °C, and 1.58 kGy h–1 at 55 and 85 °C, and subsequentlystudied by dielectric spectroscopy, NMR spectroscopy using a portable spectrometer andtensile testing. The extractable mass fraction and density were determined, and related to theimaginary part of the dielectric permittivity at 100 kHz. The ageing led to an increase in thedielectric permittivity, stiffness, density and degree of oxidation, together with a decrease inboth strain-at-break and relaxation time, as revealed by NMR spectroscopy. Except for thestrain-at-break, the properties changed in a linear fashion with increasing imaginary part ofthe dielectric permittivity at 100 kHz, with a particularly good agreement with respect to thedensity. As these properties are affected by the degree of oxidation, the results show that bothNMR using a portable spectrometer and dielectric spectroscopy can be used as conditionmonitoring techniques to detect the degree of oxidation in complex systems such as filledcopolymers.

  • 42.
    Liu, Andong
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Centra, Centrum för Biofibermaterial, BiMaC.
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Clay nanopaper composites of nacre-like structure based on montmorrilonite and cellulose nanofibers-Improvements due to chitosan addition2012Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, nr 1, s. 53-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Clay nanopaper are nanocomposites with nacre-like structure and multifunctional characteristics including high modulus, significant strength and toughness as well as fire retardancy and low oxygen transmission rate (OTR). Montmorrilonite (MTM) and nanofibrillated cellulose (NFC) hydrocolloids are combined with a chitosan (CS) solution to form high MTM content nanopaper structures by the use of a previously developed papermaking approach. Chitosan functions as flocculation agent and decreases dewatering time to less than 10% compared with MTM-NFC clay nanopaper. The effect of chitosan on the clay nanopaper structure was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Properties were measured by uniaxial tensile testing, thermogravimetric analysis (TGA), OTR and moisture adsorption experiments. A nacre-like multilayered structure was confirmed and the chitosan-clay nanopaper showed favorable mechanical properties at clay contents as high as 44-48 wt%.

  • 43.
    Liu, Dongming
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Functional polyethylene-aluminum oxide nanocomposites for insulation materials in high-voltage direct-current (HVDC) cables2015Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 44.
    Liu, Dongming
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Polyethylene – metal oxide particle nanocomposites for future HVDC cable insulation: From interface tailoring to designed performance2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Low-density polyethylene (LDPE) nanocomposites containing metal oxide nanoparticles are considered as promising candidates for insulating materials in future high-voltage direct-current (HVDC) cables. The significant improvement in dielectric properties compared with unfilled polymer is attributed to the large and active interface between the nanoparticles and the polymer. The nanoparticles may also initiate cavitation under stress and potential accelerated aging risks due to the adsorption and inactivation of the protecting antioxidants. This study is focused on the possibilities of achieving well-balanced performances of the polyethylene nanocomposites for HVDC insulation via tailoring the particle interface in the nanocomposites.

    A facile and versatile surface coating method for metal oxide particles was developed based on silane chemistry. The developed method was successfully applied to 8.5 nm Fe3O4, 25 nm ZnO and 50 nm Al2O3 particles, with the aim to develop uniform coatings that universally could be applied on individual particles rather than aggregates of particles. The surface properties of the coatings were further tailored by applying silanes with terminal alkyl groups of different lengths, including methyl (C1-), octyl (C8-) and octadecyl (C18-) units. Transmission electron microscopy, infrared spectroscopy and thermal gravimetric analysis confirmed the presence of uniform coatings on the particle surface and importantly the coatings were found to be highly porous.

    The capacity of metal oxide particles to adsorb relevant polar species (e.g. moisture, acetophenone, cumyl alcohol and phenolic antioxidant) was further assessed due to its potential impact on electrical conductivity and long-term stability of the nanocomposites. The oxidative stability of the nanocomposites was affected by the adsorption of phenolic antioxidants on particles and transfer of catalytic impurities (ionic species) from metal oxide particles to polymer matrix. It was found that carefully coated metal oxide particles had much less tendency to adsorb antioxidants. They could, however, adsorb moisture, acetophenone and cumyl alcohol. The coated particles did not emit any destabilizing ionic species into the polymer matrix. 

    The inter-particle distance of the nanocomposites based on C8-coated nanoparticles showed only a small deviation from the ideal, theoretical value, indicating a good particle dispersion in the polymer. Scanning electron microscopy of strained nanocomposite samples suggested the cavitation mainly occurred at the polymer/nanoparticles interface. The microstructural changes at polymer/nanoparticle interface were studied by small-angle X-ray scattering coupled with tensile testing. The polymer/nanoparticle interface was fractal before deformation due to the existence of the bound polymers at the nanoparticle surface. Extensive de-bonding of particles and cavitation were observed when the nanocomposites were stretched beyond a critical strain. It was found that the composites based on carefully coated particles showed higher strain at cavitation than the composites based on uncoated particles. The composites based on C8-coated nanoparticles showed the largest decrease in electrical conductivity and the lowest temperature coefficient of the electrical conductivity among the composite samples studied.

  • 45.
    Liu, Dongming
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hoang, A.T
    Chalmers University of Technology.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Pallon, Love
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gubanski, Stanislaw
    Chalmers University of Technology.
    Ohlsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Influence of nanoparticle surface coating on electrical conductivity of polyethylene/aluminium oxide nanocomposites for HVDC cable insulations2016Inngår i: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135Artikkel i tidsskrift (Fagfellevurdert)
  • 46.
    Liu, Dongming
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pallon, Love
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Zhang, Peng
    Deutsches Elektronen-Synchrotron (DESY).
    Diaz, Ana
    Paul Scherrer Institut.
    Holler, Mirko
    Paul Scherrer Institut.
    Schneider, Konrad
    Leibniz Institut für Polymerforschung Dresden.
    Olsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Yu, Shun
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cavitation in strained polyethylene/aluminium oxide nanocomposites2016Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945Artikkel i tidsskrift (Fagfellevurdert)
  • 47.
    Lu, W.
    et al.
    China.
    Fu, Ying
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Reflection and transmission2018Inngår i: Springer Series in Optical Sciences, ISSN 0342-4111, Vol. 215, s. 73-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this chapter we study how a material reflects and transmits a light beam in terms of the macroscopic effective dielectric coefficient of the material. The focus of the chapter is to extract the effective dielectric coefficient of the material using the harmonic oscillator model and the Kramers–Kronig relationship by properly designing the reflection and transmission spectroscopic measurements including the reflection and transmission spectra from and through a thin film and the reflection spectrum from a thin film on a substrate.

  • 48.
    Löfhede, Johan
    et al.
    University of Borås.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Thordstein, Magnus
    Göteborg Universitet .
    Textile Electrodes for EEG Recording: A Pilot Study2012Inngår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, nr 12, s. 16907-16919Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The overall aim of our research is to develop a monitoring system for neonatal intensive care units. Long-term EEG monitoring in newborns require that the electrodes don’t harm the sensitive skin of the baby, an especially relevant feature for premature babies. Our approach to EEG monitoring is based on several electrodes distributed over the head of the baby, and since the weight of the head always will be on some of them, any type of hard electrode will inevitably cause a pressure-point that can irritate the skin. Therefore, we propose the use of soft conductive textiles as EEG electrodes, primarily for neonates, but also for other kinds of unobtrusive long-term monitoring. In this paper we have tested two types of textile electrodes on five healthy adults and compared them to standard high quality electrodes. The acquired signals were compared with respect to morphology, frequency distribution, spectral coherence, correlation and power line interference sensitivity, and the signals were found to be similar in most respects. The good measurement performance exhibited by the textile electrodes indicates that they are feasible candidates for EEG recording, opening the door for long-term EEG monitoring applications.

  • 49.
    Lönnberg, Hanna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Fogelström, Linda
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Zhou, Qi
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Teeri, Tuula T.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Samir, Said
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    POLY 661-Grafting of poly(e-caprolactone) from microfibrillated cellulose films: for biocomposite applications2007Konferansepaper (Fagfellevurdert)
  • 50.
    Marais, Andrew
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    The use of polymeric amines to enhance the mechanical properties of lignocellulosic fibrous networks2012Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, nr 4, s. 1437-1447Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cationic polyelectrolytes (polyallylamine and polyvinylamine with different molecular masses) were adsorbed onto lignocellulosic fibres from unbleached and unbeaten spruce chemical fibres with different kappa numbers to investigate the effects on the mechanical properties of the final paper materials. Adsorption isotherms were first established to determine the maximum quantity of polymer that could be adsorbed onto each type of fibre. Paper sheets were then made with different amounts of added polyelectrolyte, and the structural and mechanical properties of the sheets were investigated, as well as the effect of an extra heating. The use of fibres with different kappa numbers led to different responses in terms of adsorption, and thus to differences in the mechanical properties of the resulting sheets. The tensile strength index was significantly increased (almost 50 % improvement in the best case) as a consequence of this polyelectrolyte adsorption onto the fibres, even at as low an adsorption level as 2 mg/g. The heating of paper sheets for 10 min at 160 A degrees C was also shown to improve the tensile strength index by about 10 % for pulps with high kappa number.

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