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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.
    Alexander Deen, Fusi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Synthetic Functionalization of Colloidal Lignin Particles for Wood Adhesive Applications2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

    Fulltekst (pdf)
    fulltext
  • 4.
    Atarijabarzadeh, Sevil
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, 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.

  • 5.
    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.

  • 6.
    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. 

    Fulltekst (pdf)
    fulltext
  • 7.
    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.

    Fulltekst (pdf)
    fulltext
  • 8.
    Bogdan, Felix
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Evaluation of different block-copolymer coatings of iron oxide nanoparticles by flash nanoprecipitation2023Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Nanopartiklar (NP) erbjuder unika möjligheter för medicinska tillämpningar, inklusive kontrollerad frisättning av cancerläkemedel, användning som bildkontrast vid avbildningsprocedurer eller hypertermisk behandling av cancerceller. Flash nanoprecipitation (FNP) producerar NPs för att kombinera dessa tillämpningar i en snabb, billig och skalbar beläggningsprocess. Användning av FNP med en Multi-Inlet Vortex Mixer (MIVM) är en lovande metod för att enkelt belägga hydrofoba oljesyra järnoxid NP (IONP) med olika biokompatibla block-copolymerer. Amfifila block-copolymerer baserade på hydrofil polyetylenglykol (PEG) och hydrofob poly(laktid) (PLA), poly(laktid-co-glykolid) (PLGA) eller poly(kaprolakton) (PCL) syntetiserades framgångsrikt. Den organiska katalysatorn 1,8-diazabicyclo[5.4.0]undec-7-en (DBU) användes för att öka biokompatibiliteten hos de resulterande polymererna PEG-PLA, PEG-PL7,5KG2,5KA och PEG2K-PCL2K. Syntes av hydroxylterminerad poly(akrylsyra) (PAA-OH) följt av polymerisation med PLGA prövades. De amfifila blockpolymererna användes i kombination med stabilisatorn polysorbat 80 (Tween80®) i FNP för att bilda nakna polymera NP med en MIVM som reaktor. DLS och STEM bekräftade partikelstorlekar mellan 50 - 100 nm. Tillsatsen av 13 ± 2 nm hydrofoba oljesyra-IONPs gav en ökning av partikelstorleken samt en ökning av partikelstabiliteten över tid. STEM-bilder visade att enstaka IONPs fästs på utsidan av de polymera NPs. Hydrofoba interaktioner mellan polymeren och oleinsyra-IONPs är möjliga. För att uppnå inkapsling av oljesyra-IONPs bör justeringar av processparametrarna för FNP övervägas i framtida forskning. Ytterligare experiment krävs för att utforska möjliga läkemedelstillsatser, frisättningsmekanismer och hypertermi hos de polymerbelagda IONP-partiklarna.

    Fulltekst (pdf)
    fulltext
  • 9.
    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.

  • 10.
    Capezza, Antonio Jose
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material. SLU.
    Sustainable Biobased Protein Superabsorbents from Agricultural Co-Products2020Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    fulltext
  • 11.
    Capezza, Antonio Jose
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Cui, Yuxiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    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 Approach2020Inngår i: Advanced Sustainable Systems, ISSN 2366-7486Artikkel i tidsskrift (Fagfellevurdert)
    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, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    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 superabsorbentsManuskript (preprint) (Annet vitenskapelig)
  • 13.
    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.  

    Fulltekst (pdf)
    fulltext
  • 14.
    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)
  • 15.
    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.

  • 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, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    A gradient-distributed liquid-metal hydrogel capable of tunable actuation2021Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 421, s. 127762-, artikkel-id 127762Artikkel i tidsskrift (Fagfellevurdert)
    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, 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.

  • 18.
    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.

  • 19. Darabi, Sozan
    et al.
    Hummel, Michael
    Rantasalo, Sami
    Rissanen, Marja
    Öberg Månsson, Ingrid
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Hilke, Haike
    Byungil, Hwang
    Skrifvars, Mikael
    Hamedi, Mahiar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Sixta, Herbert
    Lund, Anja
    Müller, Christian
    Green Conducting Cellulose Yarns for Machine Sewn Electronic TextilesManuskript (preprint) (Annet vitenskapelig)
  • 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, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    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, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Naturally-occurring bromophenol to develop fire retardant gluten biopolymers2020Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 243, artikkel-id 118552Artikkel i tidsskrift (Fagfellevurdert)
    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, 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.

  • 22.
    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 (pdf)
    thesis
  • 23.
    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. 

  • 24.
    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.

  • 25.
    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.

  • 26.
    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, E-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.

  • 27.
    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.

  • 28.
    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. 

    Fulltekst (pdf)
    fulltext
  • 29.
    Hassanzadeh, Salman
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi. Chemistry Department, School of Science, University of Tehran, Iran .
    Khoee, Sepideh
    Beheshti, Abolghasem
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, 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.

  • 30. Hauer, Bernhard
    et al.
    Engelmark Cassimjee, David Karim
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    Berglund, Per
    KTH, Skolan för bioteknologi (BIO), Biokemi.
    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)+.

  • 31.
    He, Qixiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Development of waterborne bio-based primers for metal application2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Med syftet att röra sig mot en mer hållbar ekonomi har beläggning med mer biobaserat innehåll ochmindre mängder VOC dragit till sig mer och mer uppmärksamhet. Genom att blanda olika råmaterial förberedes i denna studie vattenburna formuleringar av primerbaserade på olika alkydharts. Applicering av dessa gjordes sedan med hjälp utav roller eller luftspray påglas- och metallytor. Filmerna som erhölls studerades sedan och deras egenskaper visade sig vara moderata; de visade gott motstånd mot korrosion och högt biobaserat kolinnehåll. Dessutom utforskades biobaserad epoxiderad linoljan ihop med fyra aminbaserade härdare (diamin, polyamid,polyethylenemine och polyamine), som en del av de vattenburna primärbeläggningssystemen med syftet att ytterligare öka det biologiska innehållet. På grund av de instrinsiska egenskaperna hos den partielltepoxiderad linoljan, så som låg reaktionsaktivitet i rumstemperatur och dålig blandbarhet med vatten, var försöken att använda aminbaserade härdare till att rena epoxiderad linolja i ett vattenburet systemdock inte lyckade.

  • 32.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    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.

  • 33.
    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
  • 34.
    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.

    Fulltekst (pdf)
    fulltext
  • 35.
    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.

  • 36.
    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.

  • 37.
    Huang, Tianxiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Hydrophobization of cellulose for bio-based materials2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    Cellulosa, vilken är huvudkomponenten i växter förekommer rikligt i naturen, både på land och i havet. Cellulosabaserade material har i tusentals år använts av människan för dagliga förnödenheter som bränsle och konstruktionsmaterial. Cellulosa isolerades först av den franske forskaren Anselme Payen 1838. I det moderna samhället har applikationerna av cellulosa blivit mer omfattande i och med mer kunskap om cellulosans kemi, vilket även resulterat i modifiering av dess struktur och därmed produkter med nya egenskaper vilka kan möta dagens nya krav. I denna avhandling har kunskap om hur cellulosan kan modifieras, speciellt med avseende på att öka hydrofobiciteten, dvs att minska förmågan att absorbera vatten samt att öka kompabiliteten i kompositmaterial.Cellulosafibrer används ofta som förstärkning i kompositmaterial. I detta arbete användes en ny typ av mikrocellulosa – ett cellulosaderivat, cellulosaoxalat (COX), för framställning av polymersammansättningar. COX hydrofoberades först av maleaterad polypropylen (MAPP) eller oljesyra för att erhålla en bättre kompatibilitet med den hydrofoba matrisen av polypropylen (PP). Det konstaterades att en komposit bestående av 60% PP och 40% MAPP-hydrofoberad COX visade 16% högre draghållfasthet och 106% högre Youngs modul än ren PP. Vid användning av oljesyra för hydrofobering av COX är det möjligt att undvika att använda toxiska katalysatorer för att fullborda förestringen mellan COX och oljesyra, vilket kan leda till en mer miljövänlig process.På samma sätt användes naturligt förekommande föreningar med syftet att framställa hydrofoba cellulosabaserade textilier. Betulin, en naturprodukt isolerad från björkens bark, användes för att modifiera vätbarheten hos cellulosabaserade textilier med tre olika metoder. Textilfibrer modifierades genom att de behandlades i en betulinlösning varefter de torkades och kunde därefter uppvisa en statisk vattenkontaktvinkel (SWCA) på 153°. Därefter ytbehandlades textilfibrer med en betulinbaserad film, vilken uppvisade ett vattenavvisande värde på 80 enligt ett standardtest från American Association of Textile Chemists and Colorists (AATCC). Framställning av betulin-ympad cellulosabaserad textil, visade inte bara hydrofoba egenskaper (SWCA upp till 136°) utan även antibakteriella egenskaper med mer än 99% reduktion av bakterier.Baserat på resultaten från denna avhandling öppnas möjligheter att modifiera cellulosa och erhålla vattenavstötande eller mer kompatibla material för framställning av kompositmaterial. Ökade möjligheter att använda biprodukter, t.ex. betulin och oljesyra, från de skogsindustriella processerna i ett bioraffinaderiperspektiv, kan även bidra till mer hållbara och miljövänliga processer och ökade ekonomiska värden.

    Fulltekst (pdf)
    fulltext
  • 38.
    Huas, Hugo
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jérome, Titouan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Artificial Spider Web: Selection of Polymeric Materials for Special Effects Applications2021Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    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.

    Fulltekst (pdf)
    fulltext
  • 39.
    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 %.

  • 40.
    Ibn Yaich, Anas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, 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.

  • 41.
    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, 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.

  • 42.
    Jain, Karishma
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Wang, Zhen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Garma, Leonardo D.
    Karolinska Inst, Med Biochem & Biophys, Stockholm, Sweden..
    Engel, Emile
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Ciftci, Göksu Cinar
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Fager, Cecilia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    3D printable composites of modified cellulose fibers and conductive polymers and their use in wearable electronics2023Inngår i: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 30, artikkel-id 101703Artikkel i tidsskrift (Fagfellevurdert)
    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, Skolan för industriell teknik och management (ITM), Industriell produktion, Hållbara produktionssystem. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Zhao, Chun
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion. Beijing Information Science and Technology University.
    Chen, Mo
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Hållbara produktionssystem.
    Wang, Xi Vincent
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Feng, Lei
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Wang, Lihui
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Hållbara produktionssystem.
    A Flexible 4D Printing Service Platform for Smart Manufacturing2020Inngår i: Swedish Production Symposium, 2020Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 44.
    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.

    Fulltekst (pdf)
    Bioplastic material from microalgae
  • 45.
    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.

  • 46.
    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.

  • 47. Jönsson, C.
    et al.
    Wei, R.
    Biundo, Antonino
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. 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, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles2021Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 14, nr 19, s. 4028-4040Artikkel i tidsskrift (Fagfellevurdert)
    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, Skolan för teknikvetenskap (SCI), Centra, 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-links2020Inngår i: Continuum Mechanics and Thermodynamics, ISSN 0935-1175, E-ISSN 1432-0959Artikkel i tidsskrift (Fagfellevurdert)
    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, 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.

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  • 50.
    Karlsson, Mattias E.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Fundamentals of Polyethylene Composites for HVDC Cable Insulation – Interfaces and Charge Carriers2020Doktoravhandling, med artikler (Annet vitenskapelig)
    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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