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  • 201.
    Ek, Monica
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Cellulose films and fibres with antibacterial properties2007Konferensbidrag (Refereegranskat)
  • 202. Eldsäter, C.
    et al.
    Albertsson, A-C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Impact of degradation mechanisms on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) during composting1997Ingår i: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 48, nr 11, s. 478-483Artikel i tidskrift (Refereegranskat)
  • 203. Eldsäter, C.
    et al.
    Erlandsson, B.
    Renstad, R.
    Albertsson, A-C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    The biodegradation of amorphous and crystalline regions in film-blown poly(ε-caprolactone)2000Ingår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 41, nr 4, s. 1297-1304Artikel i tidskrift (Refereegranskat)
  • 204. Eldsäter, Carina
    et al.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    Effect of abiotic factors on the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in simulated and natural composting environments1999Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, nr 2, s. 177-183Artikel i tidskrift (Refereegranskat)
  • 205. Elsander, Anna
    et al.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Gellerstedt, Göran
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Oxalic acid formation during ECF and TCF bleaching of kraft pulp1997Ingår i: Proceedings Minimum Effluent Mills Symposium, 1997, s. 63-66Konferensbidrag (Refereegranskat)
    Abstract [en]

    The formation of oxalic acid (I) during bleaching of softwood kraft pulp was studied.  Bleaching agents used were O, H2O2, ClO2, peracetic acid (II), and O3.  The formation of I acid increased linearly with the decrease in kappa no.  II bleaching gave less I than the other bleaching agents.  In O3 bleaching ∼1/3 of the formed I was adsorbed on the pulp and not released until a later stage.

  • 206.
    Engström, Joakim
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hatton, Fiona
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    D'Agosto, F.
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS, UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), Team LCPP Bat 308F, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France .
    Lansalot, M.
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS, UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), Team LCPP Bat 308F, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France .
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Soft and rigid core latex nanoparticles prepared by RAFT-mediated surfactant-free emulsion polymerization for cellulose modification-a comparative study2017Ingår i: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 8, nr 6, s. 1061-1073Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Latex nanoparticles comprising cationically charged coronas and hydrophobic cores with different glass transition temperatures (Tg) have been prepared by surfactant-free, RAFT-mediated emulsion polymerization, where the particles form through a polymerization-induced self-assembly (PISA) type mechanism. Poly(2-dimethylaminoethyl methacrylate-co-methacrylic acid) (P(DMAEMA-co-MAA)) was utilized as a hydrophilic macroRAFT agent for the polymerization of methyl methacrylate (MMA) or n-butyl methacrylate (nBMA), respectively, resulting in two different latexes, with either a core of high (PMMA) or low (PnBMA) Tg polymer. By varying the molar mass of the hydrophobic block, latexes of different sizes were obtained (DHca. 40-120 nm). The adsorption of the latexes to cellulose model surfaces and cellulose nanofibrils (CNF) was studied using quartz crystal microbalance with dissipation monitoring (QCM-D). The surfaces with adsorbed PnBMA latexes yielded hydrophobic surfaces both before and after annealing, whereas surfaces with adsorbed PMMA latex became hydrophobic only after annealing, clearly showing the influence of the Tg of the core. The latexes were also used to modify macroscopic cellulose in the form of filter papers. Similar to the CNF surfaces, no annealing was required to achieve hydrophobic surfaces with PnBMA latexes. Finally, nanocomposites of CNF and the polymer nanoparticles were prepared through a one-pot mixing procedure. It was found that the largest synthesized PMMA latex (120 nm) facilitated a more strainable CNF network at 50% relative humidity, with a nearly 200% increase in strain at break compared to the neat CNF reference film as well as to the composite films with PnBMA latexes or to the smaller sized PMMA latexes. This difference was attributed to the spherical shape and rigidity of the large PMMA latex nanoparticles during composite formation. This highly interesting result should indeed be considered in the future design of novel biocomposites.

  • 207.
    Erdal, Nejla
    KTH, Skolan för kemivetenskap (CHE).
    Uptake and Release of Active Ingredients in Pharmaceutical Eye Drops from Silicone Hydrogel Bandage Contact Lenses2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 208.
    Erdal, Nejla B.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Adolfsson, Karin H.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    De Lima, Sara
    Karolinska Inst, St Erik Eye Hosp, Div Ophthalmol & Vis, Dept Clin Neurosci, Stockholm, Sweden..
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    In vitro and in vivo effects of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A2018Ingår i: Clinical and experimental optometry, ISSN 0816-4622, E-ISSN 1444-0938, Vol. 101, nr 3, s. 354-362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Acuvue Oasys silicone hydrogel contact lenses (Senofilcon A) are used as bandage lenses and often combined with ophthalmic solutions in the treatment of ocular diseases. Concerns have been raised regarding the compatibility and effect of eye-drop solutions on the bandage lenses, which have led to frequent replacement of lenses causing clinical problems. Some patients experience pain or discomfort during treatments and the accumulation of drugs and preservatives in lenses has been suggested as a possible reason. The aim with this study was to investigate the effect of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A in vitro and in vivo. Methods: The effect of three common ophthalmic solutions Isopto-Maxidex, Timosan and Oftaquix on Acuvue Oasys (Senofilcon A) bandage lenses was evaluated. An in vitro model method was developed where drug and preservative uptake by Acuvue Oasys was monitored with ultraviolet-visible spectroscopy and laser desorption ionisation mass spectrometry. Surface morphology changes of the lenses were evaluated using scanning electron microscopy. The method was then implemented for the in vivo pilot study evaluating lenses worn by patients. Results: In vitro model study monitoring the drug and preservatives uptake showed that the active ingredients from all the eye drops together with preservatives were taken up by the lenses in significant amounts. For the in vivo study no traces of active ingredients or preservatives could be found on the worn and treated lenses regardless of time being worn or dosage profiles. The surface morphology changes in the in vivo study were also minor in contrast to the changes observed in the in vitro scanning electron microscopy images. Conclusion: The in vivo results demonstrate minor effects of the ophthalmic solutions on the worn lenses. These results do not support the building up of preservatives and drugs on the contact lenses as the cause of pain or discomfort experienced by some patients, which is encouraging for the use of bandage lenses in combination with ophthalmic solutions.

  • 209.
    Erdal, Nejla B.
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Construction of Bioactive and Reinforced Bioresorbable Nanocomposites by Reduced Nano-Graphene Oxide Carbon Dots2018Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 3, s. 1074-1081Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioactive and reinforced poly(ϵ-caprolactone) (PCL) films were constructed by incorporation of cellulose derived reduced nanographene oxide (r-nGO) carbon nanodots. Two different microwave-assisted reduction routes in superheated water were utilized to obtain r-nGO and r-nGO-CA. For the latter, a green reducing agent caffeic acid (CA), was incorporated in the reduction process. The materials were extruded and compression molded to obtain proper dispersion of the carbon nanodots in the polymer matrix. FTIR results revealed favorable interactions between r-nGO-CA and PCL that improved the dispersion of r-nGO-CA. r-nGO, and r-nGO-CA endorsed PCL with several advantageous functionalities including improved storage modulus and creep resistance. The considerable increase in storage modulus demonstrated that the carbon nanodots had a significant reinforcing effect on PCL. The PCL films with r-nGO-CA were also evaluated for their osteobioactivity and cytocompatibility. Bioactivity was demonstrated by formation of hydroxyapatite (HA) minerals on the surface of r-nGO-CA loaded nanocomposites. At the same time, the good cytocompatibility of PCL was retained as illustrated by the good cell viability to MG63 osteoblast-like cells giving promise for bone tissue engineering applications.

  • 210. Erlandsson, Bengt
    et al.
    Albertsson, Ann-Christine
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Molecular weight determination in degraded oxidizable and hydrolyzable polymers giving deviation from accurate using calibration and the Mark-Houwink-Sakaruda (MHS) equation1997Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 57, nr 1, s. 15-23Artikel i tidskrift (Refereegranskat)
  • 211. Erlandsson, Bengt
    et al.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    Correlation between molecular weight changes and 14CO2 evolution from biodegraded 14C-labelled ethylene-vinyl alcohol copolymer and ethylene polymer1998Ingår i: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 49, s. 363-Artikel i tidskrift (Refereegranskat)
  • 212. Erlandsson, Bengt
    et al.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    The mode of action of corn starch and a pro-oxidant system in LDPE: influence of thermooxidation and UV-irradiation on the molecular weight changes1997Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 55, nr 2, s. 237-245Artikel i tidskrift (Refereegranskat)
  • 213.
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    CONTROLLED ASSEMBLY AND FUNCTIONALISATION OF CELLULOSE-BASED MATERIALS2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The environmental effects caused by the use of fossil-based resources have intensified and driven society and research towards new materials and processes that utilise renewable resources. Within the development of new materials, wood has been identified as a raw-material from which high performing materials can be derived. One such material is cellulose nanofibrils (CNFs) which are capable of replacing several currently used fossil-based materials. However, for CNFs to exhibit the required material properties they need to be chemically or physically modified. This means that the properties of the CNFs can be specifically adapted to fit the demand in particular areas, for example electrical energy storage. In these applications it is the mechanical properties; the large, easily functionalised surface and ability to be moulded into 3D shapes that make CNFs a highly interesting raw material.

    This thesis explores the formation and functionalisation of CNF- and fibre-based materials and their novel use in applications such as energy storage. The wet stability of the materials was achieved by crosslinking and ice templating the fibrils by a novel freezing procedure, which makes it possible to avoid the use of freeze-drying and subsequent crosslinking. Using colloidal probe atomic force microscopy adhesion measurements, hemiacetals were shown to be formed between the aldehyde-containing fibrils when they are brought into molecular contact, for example during ice templating. Hemiacetal crosslinked aerogels have been shaped and functionalised to demonstrate their application as biomimetic structural composites, electrical circuits and electrical cells. In addition, crosslinked, light-weight 3D fibre networks were prepared with á similar chemistry by a self-assembly process of pulp fibres. These networks could be dried under ambient conditions and the materials formed were wet-stable due to the hemiacetal crosslinks formed in the fibre–fibre contacts, which provided the networks with excellent mechanical properties and shape recovery capacity in water.

    Finally, using a newly developed polyampholyte and mixing it with CNFs, heterofunctional composite films and aerogels could be prepared. By activating crosslinkable groups in these composite materials, they were able to undergo further water based chemical functionalisation. In this highly dispersed state, the composite could be irreversibly crosslinked by a hydrothermal treatment to create transparent, low solid content hydrogels.

    Publikationen är tillgänglig i fulltext från 2020-10-11 10:00
  • 214.
    Erlandsson, Johan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ingverud, Tobias
    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.
    Granberg, H.
    Larsson, Per A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    On the mechanism behind freezing-induced chemical crosslinking in ice-templated cellulose nanofibril aerogels2018Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 40, s. 19371-19380Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The underlying mechanism related to freezing-induced crosslinking of aldehyde-containing cellulose nanofibrils (CNFs) has been investigated, and the critical parameters behind this process have been identified. The aldehydes introduced by periodate oxidation allows for formation of hemiacetal bonds between the CNFs provided the fibrils are in sufficiently close contact before the water is removed. This is achieved during the freezing process where the cellulose components are initially separated, and the growth of ice crystals forces the CNFs to come into contact in the thin lamellae between the ice crystals. The crosslinked 3-D structure of the CNFs can subsequently be dried under ambient conditions after solvent exchange and still maintain a remarkably low density of 35 kg m-3, i.e. a porosity greater than 98%. A lower critical amount of aldehydes, 0.6 mmol g-1, was found necessary in order to generate a crosslinked 3-D CNF structure of sufficient strength not to collapse during the ambient drying. The chemical stability of the 3-D structure can be further enhanced by converting the hemiacetals to acetals by treatment with an alcohol under acidic conditions.

  • 215. Escalante, Alfredo
    et al.
    Goncalves, Ana
    Bodin, Aase
    Stepan, Agnes
    Sandstrom, Corine
    Toriz, Guillermo
    Gatenholm, Paul
    Wallenberg Wood Sci Ctr, Chalmers, Sweden.
    Flexible oxygen barrier films from spruce xylan2012Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, nr 4, s. 2381-2387Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Arabinoglucuronoxylan was extracted from Norway spruce and films prepared by casting from aqueous solution. The sugar analysis and NMR confirmed that the spruce xylan was composed of arabinose, 4-O-methyl-glucuronic acid and xylose in a ratio of 1:2:11 respectively. Substitutions of 4-O-methyl-alpha-D-GlcpA at O-2 and of alpha-L-Araf at O-3 on the xylose backbone were found by NOE analysis. NOE cross-peaks indicated as well that there is at least one free xylose on the main chain present between two substitutions. Whether the distribution of side chains was random or in blocks was uncertain. The average molecular weight of the sample was determined by size exclusion chromatography to be 12,780 g/mol. Arabinoglucoronoxylan casting yielded transparent flexible films with an average stress at break of 55 MPa, strain at break of 2.7% and a Young's Modulus 2735 MPa. Wide-angle X-ray scattering analysis showed that the arabinoglucuronoxylan films were totally amorphous. Addition of sorbitol as plasticizer resulted in less strong but more flexible films (strain at break of 5%). Peaks of crystallinity could be seen in X-ray which corresponds to sorbitol crystallizing in distinct phases. The dynamic mechanical analysis showed that the arabinoglucuronoxylan film softened at a later relative humidity (80% RH) in comparison with plasticized films (60% RH). The films showed low oxygen permeability and thus have a potential application in food packaging.

  • 216.
    Evangelopoulos, Panagiotis
    KTH, Skolan för industriell teknik och management (ITM).
    Pyrolysis and Detoxification of Waste Electrical and Electronic Equipment (WEEE) for Feedstock Recycling2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Baserat på de nuvarande trenderna inom avfallssektorn för elektrisk och elektronisk avfall (WEEE) behöver den nuvarande avfallshanteringen förbättras för att godkännas av nya strikare lagstiftningarna i Europeiska Unionen. Pyrolys och termisk behandling i allmänhet kan vara värdefulla tillvägagångssätt för att sluta materialkedjan för en cirkulär ekonomi samt bidra till energibehovet i det moderna samhället.

    Pyrolys i kombination med andra förbehandlingstekniker har undersökts med fokus på material- och energiåtervinning samt separation av metaller. I avhandlingen har olika fraktioner av WEEE undersökts baserat på processkrav och fokuset i enskilda studier.

    Initialt var den experimentella undersökningen inriktad på processens primära produkter, vilket påvisade förekomsten av flertalet miljöföroreningarna liksom värdefulla monomerer för framida materialåtervinning. Detta arbete utgjordes av en korrelativ studie mellan processens behandlingstemperatur och framställningen av de huvudsakliga produkterna. Dessutom skapades en konceptuell reaktionsmekanism för nedbrytning av bisfenol A baserat på processprodukterna.

    En annan studie reducerade bromhalten i WEEE genom förbehandling i form av lösningsmedelsextraktion. Isopropanol och toluen undersöktes utifrån deras förmåga att extrahera en av de huvudsakliga flamskyddsmedlen som finns i WEEE, dvs tetrabrombisfenol A. Projektet resultatvisar att bromhalten reducerades med ca 37 %. Detta resultat bekräftades också vid efterföljande pyrolysexperiment genom reduktion eller omätbara halter av bromerade arter i pyrolysprodukterna. Toluen tycks därför vara ett lovande alternativ för förbehandlingen och kan dessutom tillhandahållas av pyrolysprocessen själv genom att utgöra en huvudsaklig komponent i framställd pyrolysolja, vilket bidrar till en mer hållbar behandlingsmetod.

    Densitetsavskiljare som används inom hanteringen av WEEE resulterar ofta i fraktioner med hög fukthalt. När sådana fraktioner utsätts för termisk behandling kommer således fukten att omvandlas till vattenånga, vilket påverkar processen. Därför gjordes experimentella försök där WEEE pyrolyserades i kvävgas och vattenånga följt av utvärdering av materialets nedbrytning i respektive miljö. Vattenånga hade negativ påverkan på pyrolysprodukterna genom ökade molekylvikter, vilket visar att vattenånga begränsar sekundära krackningsreaktioner. Dessutom visar resultaten att vattenånga komplicerar separationen av bildade oljor samt gynnar migrering av antimon från kolrest till gasfasen. Därmed anses ett torkningssteg före pyrolys av WEEE absolut nödvändigt.

    Pyrolys vid lägre temperaturer undersöktes för att studera WEEEs bräcklighet vid olika temperaturer för att förbättra metallavskiljningen från den organiska fasta restprodukten från pyrolys samt att identifiera broms fördelning bland produkterna. Resultaten indikerar att separation är möjlig vid låga temperaturer för att minimera processens energiförbrukning men minst 40 °C högre än temperaturen då materialet termiskt börjar sönderdelas. Separationen utvärderades också med fraktionering av den fasta återstoden, vilket visade att det framställda bromfria fasta produkten kan användas ytterligare för energiåtervinning.

    Slutligen testades hela processen i en kontinuerlig skruvreaktor för övergripande processutvärdering. Resultaten indikerar att de flytande produkterna från pyrolys kan användas för materialåtervinning, vilket därmed utgör en råvara avorganiska föreningar som kan användas för att tillverka ny plast eller exempelvis flytande bränsle. De bromerade föreningarna i WEEE tenderar att migrera till gasfasen. Dessutom blir separationen av metaller enklare med en ökad temperatur. Processen i allmänhet kan vara självförsörjande på energi då de bildade pyrolysgaserna innehåller tillräckligt mycket energi för att värma systemet vid kontinuerlig användning.

  • 217.
    Ezekiel Mushi, Ngesa
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer.
    Butchosa, Núria
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer.
    Zhou, Qi
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Nanopaper membranes from chitin-protein composite nanofibers: Structure and mechanical properties2014Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, nr 7, s. 40121-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chitin nanofibers may be of interest as a component for nanocomposites. Composite nanofibers are therefore isolated from crab shells in order to characterize structure and analyze property potential. The mechanical properties of the porous nanopaper structures are much superior to regenerated chitin membranes. The nanofiber filtration-processing route is much more environmentally friendly than for regenerated chitin. Minerals and extractives are removed using HCl and ethanol, respectively, followed by mild NaOH treatment and mechanical homogenization to maintain chitin-protein structure in the nanofibers produced. Atomic force microscope (AFM) and scanning transmission electron microscope (STEM) reveal the structure of chitin-protein composite nanofibers. The presence of protein is confirmed by colorimetric method. Porous nanopaper membranes are prepared by simple filtration in such a way that different nanofiber volume fractions are obtained: 43%, 52%, 68%, and 78%. Moisture sorption isotherms, structural properties, and mechanical properties of membranes are measured and analyzed. The current material is environmentally friendly, the techniques employed for both individualization and membrane preparation are simple and green, and the results are of interest for development of nanomaterials and biocomposites.

  • 218.
    Ezekiel Mushi, Ngesa
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Utsel, Simon
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Nanostructured biocomposite films of high toughness based on native chitin nanofibers and chitosan2015Ingår i: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 18, nr 2, artikel-id 99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chitosan is widely used in films for packaging applications. Chitosan reinforcement by stiff particles or fibers is usually obtained at the expense of lowered ductility and toughness. Here, chitosan film reinforcement by a new type of native chitin nanofibers is reported. Films are prepared by casting from colloidal suspensions of chitin in dissolved chitosan. The nanocomposite films are chitin nanofiber networks in chitosan matrix. Characterization is carried out by dynamic light scattering, quartz crystal microbalance, field emission scanning electron microscopy, tensile tests and dynamic mechanical analysis. The nanostructured biocomposite was produced in volume fractions of 0, 8, 22 and 56% chitin nanofibers. Favorable chitin-chitosan synergy for colloidal dispersion is demonstrated. Also, lowered moisture sorption is observed for the composites, probably due to the favorable chitin-chitosan interface. The highest toughness (area under stress-strain curve) was observed at 8 vol% chitin content. The toughening mechanisms and the need for well-dispersed chitin nanofibers is discussed. Finally, desired structural characteristics of ductile chitin biocomposites are discussed.

  • 219.
    Fagerland, Jenny
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Synthesis of degradable aliphatic polyesters: strategies to tailor the polymer microstructure2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Key factors for successful tissue engineering are the synthesis and design of the scaffold materials. Aliphatic polyesters have been studied and often used as scaffold materials for tissue engineering. However, their lack of biological cues and degradation under high-temperature processing (e.g., 3D printing) are a limitation. In this thesis, different synthesis strategies are presented which has the potential to improve the performance of aliphatic polyesters as scaffolds for tissue regeneration.

    To stimulate interactions between exogenous materials and the surrounding tissue, two different strategies were applied. Either, by designing a two component system in which the different degradation profiles of the polymers allow for sequential release of growth factors. Or, by peptide functionalization of an aliphatic polyester chain using template-assisted chemo-enzymatic synthesis. The results from the studies were successful. A hierarchical system was obtained in which the poly(L-lactide-co-glycolide)-graft-poly(ethylene glycol) methyl ether (PLGA-g-MPEG), hydroxyapatite solution formed a gel around and within the pores of the poly(L-lactide-co-ε-caprolactone) scaffold at 37 ºC, within 1 min, that was stable for 3 weeks. The peptide functionalization was also successful where an aliphatic polyester of L-lactide was functionalized with different oligopeptides using a grafter (ethyl hept-6-enoylalaninate) and chemo-enzymatic synthesis.

    The thermal properties of poly(L-lactide-co-hydroxybutyrate) were tailored (by modification of the microstructure) to potentially improve the processability of the aliphatic polyester.  The results showed that the yttrium salan catalyst was the most successful, yielding high molecular weight copolymers in shorter time. They also showed that the Tg could be tailored by varying the amount of rac-β-butyrolactone in the copolymer to better suit thermal processing techniques, such as 3D printing.

  • 220.
    Fagerland, Jenny
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Finne-Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Mapping the synthesis and the impact of low molecular weight PLGA-g-PEG on sol-gel properties to design hierarchical porous scaffolds2013Ingår i: Journal of polymer research, ISSN 1022-9760, E-ISSN 1572-8935, Vol. 21, nr 1, s. 337-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bone morphogenetic protein 2 (BMP-2)-functionalized poly(l-lactide-co-epsilon-caprolactone) (PLCL) porous scaffolds have shown promising results in bone tissue regeneration studies. It is believed that even better results are achieved by hierarchical porous scaffolds and a designed sequential release of growth factors. We therefore synthesized (l-lactide-co-glycolide)-g-poly(ethylene glycol) (PLGA-g-PEG) oligomers which could be injected into PLCL porous scaffolds. They were synthesized by ring-opening polymerization and carefully characterized by nuclear magnetic resonance spectroscopy (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The sol-gel transition temperature, pH, and functional life were determined and correlated with the molecular structure of PLGA-g-PEG. We found that low molecular weight PLGA-g-PEG was obtained and poly(l-lactide-co-glycolide-co-poly(ethylene glycol) methyl ether) (PLGA-MPEG) appeared to contribute to gelation. It was possible to design a system that formed a hydrogel within 1 min at 37 A degrees C with a pH between 6 and 7 and with a functional life of around 1 month. These low molecular weight thermosensitive PLGA-g-PEG oligomers, which can be injected into PLCL scaffolds, appear promising for bone tissue engineering applications.

  • 221.
    Fagerland, Jenny
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Pappalardo, Daniela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi. University of Sannio, Italy.
    Schmidt, Björn
    KTH, Skolan för bioteknologi (BIO), Proteinteknologi.
    Syrén, Per-Olof
    KTH, Skolan för bioteknologi (BIO), Proteinteknologi.
    Finne-Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Template-assisted enzymatic synthesis of oligopeptides from a polylactide chain2017Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, nr 12, s. 4271-4280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Peptides are often attached to polymer materials, as bioactive components, for the control of interactions between the material and its surrounding proteins and cells. However, synthesizing peptides and attaching them to polymers can be challenging and laborious. Herein, we describe the grafting of oligopeptides to an aliphatic polyester, using a one-step chemo-enzymatic synthesis with papain as the biocatalySt. To enable enzyme-mediated functionalization of the polyester, ethyl hept-6-enoylalaninate (grafter) was synthesized and attached to polylactide chains using thiol-ene click reactions. The oligopeptides were grafted onto the polylactide chains using two different synthetic routes: the grafting from strategy, in which the grafter was attached to the polyester prior to oligopeptide synthesis, or the grafting to strategy, in which oligopeptides were synthesized on the grafter first, then attached to the polymer chain. The final products were analyzed and their structures were confirmed using nuclear magnetic resonance (NMR). The peptide attachment was evaluated using size exclusion chromatography (SEC), contact angle measurement and energy-dispersive X-ray spectroscopy scanning electron microscopy (EDS-SEM). Furthermore, the mechanistic aspects of the synthesis of the oligopeptides on the grafter were studied using molecular dynamics (MD) simulations. The simulation revealed that hydrogen bonding (between the P1 amide nitrogen of the grafter backbone and the carbonyl oxygen of D158 in the papain) maintain the grafter in a productive conformation to stabilize the transition state of nitrogen inversion, a key step of the biocatalytic mechanism. Apart from being biologically relevant, both experimental and computational results suggest that the designed grafter is a good template for initiating chemo-enzymatic synthesis. The results also showed that the grafting to strategy was more successful compared to the grafting from strategy. Overall, a successful synthesis of predefined peptide functionalized polylactide was prepared, where the oligopeptides were grafted in an easy, time efficient, and environmentally friendly way.

  • 222.
    Fagerland, Karin
    KTH, Skolan för kemivetenskap (CHE).
    Stabilizer Migration in Polyolefins determined by FTIR2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of this study was to develop a method for analyzing the distribution of stabilizers, containing hindered phenols, in polyolefins with Fourier Transform Infrared Spectroscopy (FTIR). The peak from the hindered phenol is weak and difficult to detect with FTIR, but trough reaction chlorine dioxide (ClO2) a quinone structure is formed that binds water which gives a much stronger signal in the spectrum. The aim was to  investigate whether or not it is possible to relate the absorbed amount of water to the concentration of stabiliser in the polymer.

     

    The results were that the stabilizers in a material can be related to the water absorption within a material, but not between different materials. This is based on the result from FTIR line scan that shows how the water absorption peak of a ClO2 exposed PP follows the same pattern as the ester peak of an unexposed PP over a cross section. The water absorption could not be related to the amount of stabilizers when different materials were compared since the materials absorbed unequal amounts of water.

     

    The water absorption peak increases with time until it stabilizes after 6 days (144 hours), thus when all hindered phenols have reacted with chlorine dioxide. The concentration of chlorine dioxide was of less importance for the water absorption as long as ClO2 was in excess relative the hindered phenols, for this study, 0,1 g/L was enough.  It was also concluded that reaction with ClO2 was more effective in 50°C than in room temperature since a larger water absorption peak was obtained at this temperature. The method can also be considered repeatable within a specific material since similar values ​​of the water absorption peak was obtained at separate experiments.

     

    Irganox 1330 was identified with HPLC in all of the polyolefins. There were also other hindered phenols present in most of the other polymers but they could not be identified due to overlaps. Because of the similar molecular structure of Irganox 1010 and Irganox 1076, it was impossible to achieve separation with an isocratic HPLC since they were affected in the same way by the solid and mobile phase.

     

  • 223.
    Fateh-Alavi, Kamyar
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Effect of stabilizers on surface oxidation of silicone rubber by corona discharge2004Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 84, nr 3, s. 469-474Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crosslinked polydimethylsiloxane (PDMS) containing Irganox(R) 1076, Tinuvin(R) 770 or lrganox(R) 565, prepared by swelling PDMS in a solution of one of these stabilizers in n-hexane, was exposed to a corona discharge and the corona exposure time (tau(crit)) to form a brittle, silica-like layer was determined by optical microscopy. The critical corona exposure time showed a linear increase with increasing stabilizer concentration; Tinuvin 770 showed the highest efficiency and Irganox 1076 the lowest. The increase in tau(crit) on corona exposure of the stabilized samples with reference to the value for unstabilized PDMS was similar to that reported earlier for air plasma exposed samples. The efficiency of the stabilizers towards corona-induced surface oxidation of PDMS was also confirmed by X-ray photoelectron spectroscopy.

  • 224.
    Fateh-Alavi, Kamyar
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner, Polymerteknologi.
    A rapid microwave-assisted solvent extraction method for assessment of stabilizer concentration in crosslinked polydimethylsiloxane2004Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 93, nr 5, s. 2185-2192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crosslinked polyclimethylsiloxanes were prepared containing 0.05 to 0.2 wt % of either a phenolic antioxidant (Irganox(R) 1010) or a hindered amine stabilizer (Tinuvin(R) 144). The stabilizer concentration was assessed by HPLC and UV-Vis spectroscopy of Soxhlet and microwave-assisted solvent extracts. Almost complete recovery of stabilizer was achieved with Soxhlet extraction. High stabilizer recovery was achieved when acetone was used as the solvent in the microwave-assisted extraction. HPLC was shown to be an efficient method for determining the concentration of Irganox 1010. For Tinuvin 144 the selectivity of both UV-Vis spectroscopy and HPLC was poor, leading to imprecise evaluation of the antioxidant concentration. The loss of stabilizer by migration from polymer to hot water (75 and 95degreesC) was monitored for the systems stabilized with Irganox 1010 and the diffusion coefficient of the antioxidant in the polymer was determined.

  • 225.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Tunable chitosan hydrogels for adsorption: Property control by biobased modifiers2018Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 196, s. 135-145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A sustainable strategy to fabricate chitosan-based composite hydrogels with tunable properties and controllable adsorption capacity of trace pharmaceuticals was demonstrated. Two biobased modifiers were utilized to tune the properties, nano-graphene oxide (nGO) derived from chitosan via microwave-assisted carbonization and oxidation, and genipin as the crosslinking agent. An increase in genipin content facilitated an increase in the degree of crosslinking as shown by improved storage modulus and decreased swelling ratio. Increasing nGO content changed the surface microtopography of the hydrogel which correlated with the surface wettability. nGO also catalyzed the genipin-crosslinking reaction. The hydrogel was further shown to be an effective adsorbent for a common anti-inflammatory drug, diclofenac sodium (DCF), with the removal efficiency ranging from 91 to 100% after 48 h. DCF adsorption efficiency could be tuned through simple alteration of nGO and genipin concentration, which provides promising potential for this environmental-friendly adsorbent in removal of DCF from pharmaceutical waste water.

  • 226.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Rajarao, Gunaratna Kuttuva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymerteknologi.
    Microwave carbonized cellulose for trace pharmaceutical adsorption2018Ingår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 346, s. 557-566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A promising sustainable strategy to valorize cellulose to high-value adsorbents for trace pharmaceuticals, like diclofenac sodium (DCF), in the water is demonstrated. Carbon nanospheres (CN) as the DCF adsorbent were derived from cellulose through a one-pot microwave-assisted hydrothermal carbonization method. CN exhibited efficient DCF removal (100% removal of 0.001 mg/mL DCF in 30 s and 59% removal of 0.01 mg/mL DCF in 1 h). The adsorption kinetics and isotherm data were well-fitted with the pseudo-second-order kinetic model and Langmuir model, respectively. The adsorption process was endothermic and spontaneous as confirmed by the thermodynamic parameters. Multiple characterization techniques including SEM/EDS, FTIR, FTIR-imaging and zeta potential were applied to qualitatively investigate the adsorption process. π-π stacking and hydrogen bonding were proposed as the dominant adsorption interactions. CN also demonstrated effective adsorption capacity towards three other commonly-detected contaminants in the wastewater including ketoprofen (KP), benzophenone (BZP), and diphenylamine (DPA), each bearing partial structural similarity with DCF. The affinity of the contaminants towards CN followed the order DPA > BZP > DCF > KP, which could be explained by the different configurations and chemical units. It was speculated that for DCF and KP, the steric hindrance and electrostatic repulsion produced by dissociated carboxyl groups can impede the adsorption process as compared to DPA and BZP. This methodology could offer further insights into the drug adsorption on the cellulose-derived carbon adsorbents and the use of bioderived carbons for treatment of wastewaters contaminated with pharmaceuticals.

  • 227.
    Feng, Zhaoxuan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Simeone, Antonio
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Biobased Nanographene Oxide Creates Stronger Chitosan Hydrogels with Improved Adsorption Capacity for Trace Pharmaceuticals2017Ingår i: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 5, nr 12, s. 11525-11535Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A promising green strategy for the fabrication of fully biobased chitosan adsorbents for wastewater purification is presented. Nanographene oxide (nGO)-type carbon dots were derived from chitosan (nGOCS) or from cellulose (nGOCL) through a two-step process including microwave-assisted hydrothermal carbonization and oxidation. Finally, nGO were evaluated as biobased property enhancers in chitosan hydrogel adsorbents. Macroporous chitosan hydrogels were synthesized by cross-linking with genipin, and the incorporation of nGO into these hydrogels was shown to facilitate the cross-linking reaction leading to more robust 3D cross-linked networks. This was evidenced by the increased storage modulus and by the swelling ratio that decreased from 5.7 for pristine chitosan hydrogel to 2.6 for hydrogel with 5 mg/mL nGOCS and 3.3 for hydrogel with 5 mg/mL nGOCL. As a further proof of the concept the hydrogels were shown to be effective adsorbent for the common anti-inflammatory drug diclofenac sodium (DCF). Here, the addition of nGO promoted the DCF adsorption process leading to 100% removal of DCF after only 5 h. The synergistic effect of electrostatic interactions, hydrogen bonding, and pi-pi stacking could explain the high adsorption of DCF on the hydrogels. The developed biobased CS/nGO hydrogels are thus promising adsorbents with great potential for purification of trace pharmaceuticals from wastewater.

  • 228. Ferrero, B.
    et al.
    Boronat, T.
    Moriana, Rosana
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Fenollar, O.
    Balart, R.
    Green composites based on wheat gluten matrix and posidonia oceanica waste fibers as reinforcements2013Ingår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 34, nr 10, s. 1663-1669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, green composites from renewable resources were manufactured and characterized. A fibrous material derived from Posidonia oceanica wastes with high cellulose content (close to 90 wt% of the total organic component) was used as reinforcing material. The polymeric matrix to bind the fibers was a protein (wheat gluten) type material. Composites were made by hot-press molding by varying the gluten content on composites in the 10-40 wt% range. Mechanical properties were evaluated by standardized flexural tests. Thermo-mechanical behavior of composites was evaluated with dynamic mechanical analysis (torsion DMA) and determination of heat deflection temperature. Morphology of samples was studied by scanning electronic microscopy and the water uptake in terms of the water submerged time was evaluated to determine the maximum water uptake of the fibers in the composites. Composites with 10-40 wt% gluten show interesting mechanical performance, similar or even higher to many commodity and technical plastics, such as polypropylene. Water resistance of these composites increases with the amount of gluten. Therefore, the sensitiveness to the water of the composites can be tailored with the amount of gluten in their formulation.

  • 229.
    Finne Wistrand, Anna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Polylactide:  2011Ingår i: Handbook of Engineering and Speciality Thermoplastics: Polyethers and Polyesters / [ed] S. Thomas and V. P.M., Hoboken, NJ, USA: John Wiley & Sons, 2011, s. 349-376Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    The production of durable functional products without using petroleumbased raw materials is a focus of much academic research today but it is also prioritized by many industries. Many questions still remain concerning the use, production and properties of bio-based and/or degradable polymers and whether or not they are more environmentally friendly than oil-based products. Polylactide is a bio-based compostable thermoplastic that is considered as one of the most promising materials for replacement of traditional volume plastics. The properties of polylactide can be tuned to resemble polystyrene, poly(ethylene terephthalate) or polyolefins by controlling the stereochemistry by copolymerization or blending. This chapter reviews the life-cycle of polylactide based materials as well as the properties and applications. The recent trends in the area are also discussed.

  • 230. Finnveden, G
    et al.
    Albertsson, A-C.
    Berendson, J.
    Eriksson, E.
    Höglund, L-O.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Sundquist, J-O.
    Solid waste treatment within the framework of life-cycle assessment1995Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 3, s. 189-Artikel i tidskrift (Refereegranskat)
  • 231. Flink, Johannes
    et al.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    The effects of lignin structure from treatment of pulp with activated 1-hydroxybenzotrazole.1997Ingår i: Proceedings 9th Int. Symp. Wood Pulp Chem., 1997Konferensbidrag (Refereegranskat)
  • 232.
    Flock, Sofia
    KTH, Skolan för kemivetenskap (CHE).
    Comparison of enzymatic and refining treatment of pulp fibres for strength improvement2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Today, in pulp and paper industry, refining is used for strength improvement. This process requires energy and therefore, alternative methods with less energy consumption are of interest for the industry. In tissue production, only small energy consumption is used for refining and an enzymatic treatment could possibly replace the refining process. Therefore, a quantitative comparison between refining and enzymatic treated pulp as a function of grammage was done in this study. To find out if it was possible to replace refining by enzymes, a bleached kraft softwood pulp from pine and spruce was used. The pulp was subjected to enzymatic treatments of two different monocomponent endoglucanases and by mechanical treatment by a Voith laboratory refiner for comparison. To investigate different properties of the samples, tensile test, stretch at break and Schopper-Riegler was performed. The experiments in this study demonstrated that the enzymatic treatment did not give any effect on strength or dewatering. Therefore, enzymes cannot replace refining by the method used in this study.

  • 233.
    Fogelström, Linda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Hansson, Susanne
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Linear vs. Hyperbranched Polymers in the Preparation of Polymer/Clay NanocompositesManuskript (preprint) (Övrigt vetenskapligt)
  • 234. Fonseca, R. D.
    et al.
    Correa, D. S.
    Paris, E. C.
    Tribuzi, V.
    Dev, Apurba
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Voss, T.
    Aoki, P. H. B.
    Constantino, C. J. L.
    Mendonca, C. R.
    Fabrication of zinc oxide nanowires/polymer composites by two-photon polymerization2014Ingår i: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 52, nr 4, s. 333-337Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an approach to fabricate ZnO nanowires/polymer composite into three-dimensional microstructures, based on two-photon polymerization direct laser writing, a fabrication method that allows submicrometric spatial resolution. The structural integrity of the structures was inferred by scanning electron microscopy, while the presence and distribution of ZnO nanowires was investigated by energy dispersive X-ray, Raman spectroscopy, and X-ray diffraction. The optical properties of the produced composite microstructures were verified by imaging the characteristic ZnO emission using a fluorescence microscope. Hence, such approach can be used to develop composite microstructures containing ZnO nanowires aiming at technological applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014, 52, 333-337 Zinc oxide (ZnO) has proven to be a promising material for optoelectronic devices operating in the blue to near-UV spectral region. While ZnO/polymer composite films have been readily produced via cast and spin coating, these standard approaches do not allow the fabrication of three-dimensional (3D) microstructures due to the lack of spatial resolution. In this work, 3D microstructures of composites made up of acrylic resin and ZnO nanowires are created by using two-photon polymerization.

  • 235.
    Forcyde, Ness
    KTH, Skolan för kemivetenskap (CHE).
    Removal of Residual Monomers from Polymer Suspensions2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    One of the challenges with suspension polymerization is the removal of residual monomers. Environmental regulations and market preferences are the main driving forces behind the development of novel methods and improvement of current methods. In this work, the removal of monomers has been studied using two types of chemistries: post-polymerization with radical initiators, and aza-Michael addition. Two radical initiators with different degrees of hydrophobicity were used to polymerize residual monomers in polymer particle dispersions. Results show that both initiators succeeded in removing residual monomers, but the hydrophilic initiator is more efficient than the hydrophobic initiator. Two different substrates have been amine-functionalized and reacted with methyl acrylate (monomer) in water. The functionalized substrates were characterized using Kaiser test and UV/Vis spectroscopy. The heterogeneous nature of one of the substrates seems to affect the reproducibility of the analysis results. Data suggest that the amine-functionalized substrates react with methyl acrylate at 60 °C in water and full conversion may be achieved using stoichiometric ratios. However, the amount of results was limited and more experiments are needed.

  • 236.
    Forsling, Josefine
    KTH, Skolan för kemivetenskap (CHE).
    Zwitterjoniska homo- och blocksampolymer framställda med RAFT-polymerisation och dessas adsorption till cellulosaytor2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Thermo-responsive polymers were directly polymerized from the zwitterionic monomer sulfobetaine methacrylate (SBMA). The polymerizations were performed under homogenous aqueous conditions employing the controlled radical polymerization reversible-addition fragmentation chain transfer (RAFT). 4-Cyano-4-(phenylcarbonothioylthio)pentanoic acid (CTP) was employed as RAFT agent in polymerization of homopolymers poly (sulfobetaine methacrylate) (PSBMA) The target molar-mass for the homopolymers extended from 10.0 kDa to 200 kDa. The reactions were carried out in a salt solution (0.50 M NaCl) where the salt operated as screening agents for the attractive charges within the zwitterionic system according to the anti-polyelectrolyte effect, meaning that added salt enhanced the solubility. The phase transition of the polymers was investigated with UV-Vis spectroscopy where an upper critical solution temperature (UCST) was observed for the systems investigated, except for the two smallest polymers possessing targeted molar masses of 10.0 kDa and 25.0 kDa, respectively. The UCSTs for these polymers were probably below the temperature investigated due to the low molar-mass. The UCSTs for the polymers in this study were found to depend on both the molar-mass and the concentration of polymer in the solution investigated.

    An end-functionalized biopolymer (BP) ,was employed as a macroRAFT from which SBMA was polymerized. This resulted in a new type of block copolymer: BP-b-PSBMA. The reactions for the block copolymer were carried out under same conditions as for the homopolymers.

    Besides the investigation of the UCST for both homopolymers PSBMA and block copolymers PB-b-PSBMA, an investigation regarding the adsorption of selected polymers on cellulose were performed by quartz crystal microbalance with dissipation (QCM-D) measurements. The QCM-D crystals employed were modified which resulted in a negatively charged cellulose model surface. Besides QCM-D measurements, cellulose filter papers composed of uncharged cellulose fibers were also employed in the investigation of adsorption for the selected polymers. FT-IR measurements were performed on the filter papers for detection of carbonyl peaks that could indicate a successful adsorption of the polymers.

    Proton nuclear magnetic resonance (1H NMR) analyses were performed to determine the conversion and the kinetics of the polymerizations. The majority of the polymers possessed pseudo-first order kinetics and additionally exhibited low molar-mass dispersity ĐM (ĐM = Mw/Mn). ĐM values were obtained from size exclusion chromatography (SEC) and were a further verification of a successfully controlled radical polymerization. The surface structures of the cellulose model surface after the adsorption were further evaluated by atomic force microscopy (AFM) micrographs taken of the surfaces. The micrographs revealed a significant difference between the virgin cellulose model surfaces in comparison to the surface with adsorbed BP-b-PSBMA200.

  • 237. Frostell, Claes
    et al.
    Bjorling, Gunilla
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Aune, Ragnhild E.
    Tracheal implants revisited2017Ingår i: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 389, nr 10075, s. 1191-1191Artikel i tidskrift (Refereegranskat)
  • 238.
    Fu, Qiliang
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Honeycomb like templates prepared from balsa wood2015Ingår i: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the current study, we have used sodium chlorite and sodium hydroxide as extraction solutions, to remove lignin and hemicelluloses from the Balsa (Ochroma Lagopus) wood tissues, without damaging the wood honeycomb architecture. Surface morphologies are studied using scanning electron microscopy (SEM). In addition, sugars analysis of the chemically extracted wood is reported. 

  • 239.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Mathisen, T.
    Finne Wistrand, Anna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Minimizing the time gap between service lifetime and complete resorption of degradable melt-spun multifilament fibers2019Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 163, s. 43-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have succeeded to modulated the degradation rate of poly(L-lactide) (PLLA) melt-spun multifilament fibers to extend the service lifetime and increase the resorption rate by using random copolymers of L-lactide and trimethylene carbonate (TMC). The presence of TMC units enabled an overall longer service lifetime but faster degradation kinetics than PLLA. By increasing the amount of TMC up to 18 mol%, multifilament fibers characterized by a homogenous degradation profile could be achieved. Such composition allowed, once the mechanical integrity was lost, a much longer retention of mechanical integrity and a faster rate of mass loss than samples containing less TMC. The degradation profile of multifilament fibers consisting of (co)polymers containing 0, 5, 10 and 18 mol% of TMC has been identified during 45 weeks in vitro hydrolysis following the molecular weight decrease, mass loss and changes in microstructure, crystallinity and mechanical properties. The fibers degraded by a two-step, autocatalyzed bulk hydrolysis mechanism. A high rate of molecular weight decrease and negligible mass loss, with a consequent drop of the mechanical properties, was observed in the early stage of degradation for fibers having TMC content up to 10 mol%. The later stage of degradation was, for these samples, characterized by a slight increase in the mass loss and a negligible molecular weight decrease. Fibers prepared with the 18 mol% TMC copolymer showed instead a more homogenous molecular weight decrease ensuring mechanical integrity for longer time and faster mass loss during the later stage of degradation.

  • 240.
    Fuoco, Tiziana
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pappalardo, Daniela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters2017Ingår i: CATALYSTS, ISSN 2073-4344, Vol. 7, nr 2, artikel-id 64Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Linear aliphatic polyesters are degradable thermoplastic polymers, which can be obtained by ring-opening polymerization (ROP) of cyclic esters through a coordination-insertion mechanism. Aluminum based organometallic complexes have a leading position as efficient catalysts for this polymerization process. Aluminumalkyl complexes bearing salicylaldiminato ligands, although less explored, have been shown to be efficient and versatile catalysts for the ROP of various cyclic esters. These species have the potential to function as active catalysts in the ROP because of their less coordinatively saturated nature with respect to analogous SALEN-type complexes. They have been used as efficient catalysts in the ROP of commercially available cyclic esters, such as epsilon-caprolactone, L-lactide, rac-lactide, and glycolide. Moreover, they resulted in efficient catalysts for the ROP of cyclic esters with large ring-size and for the ROP of functionalized lactide. Furthermore, they have been used in the co- and ter-polymerization of various cyclic esters affording well controlled polymerization and a plethora of microstructural architectures, ranging from random to block to multiblock.

  • 241.
    Galland, Sylvain
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer.
    Cellulose network materials - compression molding and magnetic functionalization2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 242.
    Galland, Sylvain
    et al.
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ström, Valter
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer.
    Cellulose nanofibrils decorated by inorganic nanoparticles and used in magnetic nanocomposite membranes of high toughnessManuskript (preprint) (Övrigt vetenskapligt)
  • 243. Gallet, G.
    et al.
    Lämpiänen, R.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Characterisation by SPME-GC-MS of matrix changes of poly(L-lactide) exposed to outdoor soil environment2001Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 71, s. 147-Artikel i tidskrift (Refereegranskat)
  • 244. Gallstedt, M.
    et al.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Packaging-related properties of alkyd-coated, wax-coated, and buffered chitosan and whey protein films2004Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 91, nr 1, s. 60-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Packaging-related properties of coated films of chitosan-acetic acid salt and whey protein concentrate (WPC) were studied. Chitosan (84.7% degree of deacetylation) and WPC (65-67% protein) were solution cast to films. These films are potential oxygen barriers for use in packaging. Coatings of wax or alkyds were used to enhance the water-barrier properties. The packaging-related properties of chitosan films treated in a buffering solution, with a pH of 7.8, were also investigated. The coated films were characterized with respect to Cobb absorbency, overall migration to water, water vapor transmission rate, and oxygen permeability. The creasability and bending toughness were determined. The wax was a more efficient barrier to liquid water and 90-95% relative humidity than the alkyd. However, the alkyd-coated material had superior packaging-converting properties. The alkyd-coated WPC and chitosan-salt films were readily folded through 180degrees without any visible cracks or delamination. The overall migration from the alkyd-coated materials was below the safety limit, provided the coat weight was higher than 7.5 mg/cm(2) on WPC and 2.1 mg/cm(2) on chitosan-salt. The barrier properties of chitosan film under moist conditions were improved by the buffer treatment. However, the buffering also resulted in shrinkage of the film.

  • 245. Gallstedt, Mikael
    et al.
    Pettersson, Henrik
    Johansson, Therese
    Newson, William R.
    Johansson, Eva
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Film Extrusion of Crambe abyssinica/Wheat Gluten Blends2017Ingår i: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, nr 119, artikel-id e54770Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a high-protein crambe meal that has limited value, as it is not fit for food or feed use. However, it contains proteins that could potentially make it a suitable raw material for higher-value products. The purpose of this study was to find methods of making this side stream into extruded films, showing that products with a higher value can be produced. The study mainly considered the development of material compositions and methods of preparing and extruding the material. Wheat gluten was added as a supportive protein matrix material, together with glycerol as a plasticizer and urea as a denaturant. The extrudate was evaluated with respect to mechanical (tensile testing) and oxygen barrier properties, and the extrudate structure was revealed visually and by scanning electron microscopy. A denser, more homogeneous material had a lower oxygen transmission rate, higher strength, and higher extensibility. The most homogeneous films were made at an extruder die temperature of 125-130 degrees C. It is shown here that a film can be extruded with promising mechanical and oxygen barrier properties, the latter especially after a final compression molding step.

  • 246. Gan, Zhixing
    et al.
    Xu, Hao
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellulär biofysik. KTH, Centra, Science for Life Laboratory, SciLifeLab. Ningbo University, China.
    Photoluminescence of Diphenylalanine Peptide Nano/Microstructures: From Mechanisms to Applications2017Ingår i: Macromolecular rapid communications, ISSN 1022-1336, E-ISSN 1521-3927, Vol. 38, nr 22, artikel-id 1700370Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Diphenylalanine (Phe-Phe, FF) molecules, which can self-assemble into highly ordered nano/microstructures, have increasingly aroused intense interests due to their special optical properties. In this review, recent advances in photoluminescence (PL) of supramolecular architectures of FF-based peptide and the underlying mechanisms are highlighted. Mainly deep ultraviolet emission at around 285 nm and/or blue emission at approximate to 450 nm are observed in various FF peptide structures and its derivatives, which are primarily interpreted by quantum confinement effects, shallow radiative traps, and electron delocalization via hydrogen bonds in beta-sheet structures. Furthermore, current applications of such fluorescent peptide nano/microstructures are also reviewed here, e.g., probing the number of water molecules confined in FF, temperature sensing, and visualization of deep ultraviolet beam. Yet, the PL mechanism is still under fierce debate and the application based on fluorescence is constantly under exploration. Thus, this review is endeavored to boost future explorations on the PL of the bioinspired FF peptide nano/microstructures.

  • 247.
    Garcia-Garcia, Daniel
    et al.
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Balart, Rafael
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Lopez-Martinez, Juan
    UPV, ITM, Plaza Ferrandiz y Carbonell 1, Alicante 03801, Spain..
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Moriana, Rosana
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Optimizing the yield and physico-chemical properties of pine cone cellulose nanocrystals by different hydrolysis time2018Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 5, s. 2925-2938Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanocrystals (CNCs) were isolated for the first time from pine cones (PC) by alkali and bleaching treatments and subsequent sulfuric acid hydrolysis (64%) at 45 degrees C. The influence of the hydrolytic reaction time (30, 45, and 90 min) on the yield, chemical composition and structure, and thermal stability of CNCs was evaluated. The removal of non-cellulosic constituents during the alkaline and bleaching treatment resulted in high pure cellulosic fibres. The isolation of CNCs from these cellulosic fibres at different reaction times was verified by the nano-dimensions of the individual crystals (< 3 and < 335 nm of average diameter and length, respectively). The highest yield (15%) and the optimum CNCs properties in terms of aspect ratio, thermal stability and crystallinity were obtained for an extraction time of 45 min. PC appeared to be a new promising source of cellulose fibres and CNCs with potential to be applied as reinforcement in composites and for food-packaging.

  • 248.
    Gard Timmerfors, Jessica
    KTH, Skolan för kemivetenskap (CHE).
    Material analysis of a self-reinforced poly (ethyleneterephthalate) composite2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Methods as infrared spectroscopy, X-ray, birefringence and DSC are often used on polymer

    fibres or films to detect changes in crystallinity, chain orientation and other microstructural

    changes in the material.

    In this study a self-reinforced Poly(ethylene Terephthalate) (PET) composite is processed

    with different degree of shrinkage or elongation during heating and forming. Normal spun

    PET fibre can be cold drawn to increase the crystallinity and mechanical properties. This

    study investigates whether this phenomenon is detectable for fibres in composites and can

    explain the change in mechanical properties at different elongations during processing.

    Furthermore, this study investigates if these common analysis methods for fibre or films can

    be used to analyse a PET self-reinforced composite.

    X -ray indicates no difference in the theoretical size of the crystals.

    All samples were birefringence, which indicate an anisotropic material, crystals, however due

    to a lack of equipment the changes in the crystal orientation could not be fully investigated.

    Reflective IR-analysis did not work on the composite and transmission appears to work.

    Interpretation models as a common baseline or baseline of each peak do not work. Lack of

    expertise and information of matrix make batch peak analyse not viable, but this

    interpretation model might work.

  • 249.
    Gedde, Ulf
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hjertberg, Thomas
    Borealis.
    Costa, Francis
    Borealis/Linz.
    Oderkerk, Jeroen
    Borealis.
    Polyolefin composition with increased resistance against degradation caused by chlorine dioxide2011Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The present invention relates to a polyolefin composition with increased resistance to degradation caused by ClO2-containing water and to an article made of such a polyolefin composition. The polyolefin composition comprises a polyolefin base resin (A), at least one antioxidant (B) having an initial oxygen induction time (OIT190°C) of more than 35 min., determined according to the OIT190°C test described herein and having a slope of the curve, when OIT190°C, in minutes, is recorded as a function of exposure time, in minutes, in a chlorine dioxide degradation test as described herein, of at least -0.07, and c) at least one antioxidant (C) having an initial oxygen induction time (OIT190°C) of not more than 35 min., determined according to the OIT190°C test described herein and having a slope of the curve, when OIT190°C, in minutes, is recorded as a function of exposure time, in minutes, in a chlorine dioxide degradation test as described herein, of less than -0.07, wherein said polyolefin composition shows a resistance against water containing 10 ppm chlorine dioxide at 70 °C and a pH of 6.8 ± 0.1 of at least 450 min., expressed as the time to reach 50% of the initial oxygen induction time at 210 °C (OIT(210°C),50%), determined according to the chlorine dioxide degradation test as described herein. The present invention further relates to the use of the polyolefin composition for the production of an article, e.g. a pipe, a fitting or a storage container and to the use of the polyolefin composition for increasing the resistance of an article against degradation caused by contact with ClO2-containing water.

  • 250.
    Gedde, Ulf W
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Untitled2016Ingår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 55, s. A2-A2Artikel i tidskrift (Övrigt vetenskapligt)
2345678 201 - 250 av 782
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