Digitala Vetenskapliga Arkivet

Change search
Refine search result
1234567 1 - 50 of 1936
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abada, Maria
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Fossum, Elin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Brandt, Louise
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Åkesson, Anton
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Property prediction of super-strong nanocellulose fibers2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The innovative technology behind production of strong biofilaments involves the process of spinning filaments from nanoparticles extracted from wood. These nanoparticles are called cellulose nanofibrils (CNFs). The spun filaments can have high mechanical properties, rivaling many other plant based materials, and could be an environmentally friendly replacement for many materials in the future such as fabrics and composites. Before mass production might be possible, the optimal dispersion properties must be determined for the intended use, with regard to concentration, method of oxidation (TEMPO-oxidation or carboxymethylation) and pretreatment through sonication and centrifugation.

    In this bachelor’s thesis attributes of spun filaments were investigated in order to find a correlation between mechanical properties and the effects of concentration, method of oxidation as well as sonication and centrifugation of the dispersions. The mechanical properties were also compared to the fibrils’ ability to entangle and align during flow-focusing. A variety of analytical methods: flow-stop, tensile testing, scanning electron microscopy (SEM) and wide angle X-ray scattering (WAXS) were implemented for the dispersions and filaments.

    The results from this study show that flow-stop analysis could be used to determine which CNF dispersions are spinnable and which are non-spinnable, along with which spinnable dispersion would yield the strongest filament. It was also concluded that crystallinity of fibrils affects the mechanical properties of filaments and that TCNFs are generally more crystalline than CMCs. Pretreatment through sonication and centrifugation seems to have a negative impact on spinnability and sonication in combination with low concentration seems to lead to non-spinnable conditions. On the other hand, sonicated dispersions seem to yield a greater number of samples without aggregates than non-sonicated ones. Aggregates, however, seem to only affect ultimate stress out of the measured mechanical properties. Furthermore, concentration and viscosity affect spinnability and CMC dispersions seem to yield thicker filaments than TCNF dispersions. However, due to lack of statistically validated data any definitive conclusions could not be drawn.

    Download full text (pdf)
    fulltext
  • 2.
    Abbasi Aval, Negar
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. Isfahan Univ Technol, Dept Mat Engn, Biomat Res Grp, Esfahan 8475683777, Iran.;Isfahan Univ Med Sci, Sch Med, Dept Anat Sci, Esfahan, Iran..
    Emadi, Rahmatollah
    Isfahan Univ Technol, Dept Mat Engn, Biomat Res Grp, Esfahan 8475683777, Iran..
    Valiani, Ali
    Isfahan Univ Med Sci, Sch Med, Dept Anat Sci, Esfahan, Iran..
    Kharaziha, Mahshid
    Isfahan Univ Technol, Dept Mat Engn, Biomat Res Grp, Esfahan 8475683777, Iran..
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    An aligned fibrous and thermosensitive hyaluronic acid-puramatrix interpenetrating polymer network hydrogel with mechanical properties adjusted for neural tissue2022In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 57, no 4, p. 2883-2896Article in journal (Refereed)
    Abstract [en]

    Central nervous system (CNS) injuries such as stroke or trauma can lead to long-lasting disability, and there is no currently accepted treatment to regenerate functional CNS tissue after injury. Hydrogels can mimic the neural extracellular matrix by providing a suitable 3D structure and mechanical properties and have shown great promise in CNS tissue regeneration. Here we present successful synthesis of a thermosensitive hyaluronic acid-RADA 16 (Puramatrix (TM)) peptide interpenetrating network (IPN) that can be applied in situ by injection. Thermosensitive hyaluronic acid (HA) was first synthesized by combining HA with poly(N-isopropylacrylamide). Then, the Puramatrix (TM) self-assembled peptide was combined with the thermosensitive HA to produce a series of injectable thermoresponsive IPNs. The HA-Puramatrix (TM) IPNs formed hydrogels successfully at physiological temperature. Characterization by SEM, rheological measurements, enzymatic degradation and swelling tests was performed to select the IPN optimized for neurologic use. SEM images of the optimized dry IPNs demonstrated an aligned porous structure, and the rheological measurements showed that the hydrogels were elastic, with an elastic modulus of approximately 500 Pa, similar to that of brain tissue. An evaluation of the cell-material interactions also showed that the IPN had biological characteristics required for tissue engineering, strongly suggesting that the IPN hydrogel possessed properties beneficial for regeneration of brain tissue.

  • 3.
    Abdel Aziz, Ilaria
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Basque Country UPV EHU, Spain.
    Gladisch, Johannes
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Griggs, Sophie
    Univ Oxford, England.
    Moser, Maximilian
    Univ Oxford, England.
    Biesmans, Hanne
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Beloqui, Ana
    Univ Basque Country UPV EHU, Spain; Basque Fdn Sci, Spain.
    McCulloch, Iain
    Univ Oxford, England.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Stavrinidou, Eleni
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Drug delivery via a 3D electro-swellable conjugated polymer hydrogel2024In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518Article in journal (Refereed)
    Abstract [en]

    Spatiotemporal controlled drug delivery minimizes side-effects and enables therapies that require specific dosing patterns. Conjugated polymers (CP) can be used for electrically controlled drug delivery; however so far, most demonstrations were limited to molecules up to 500 Da. Larger molecules could be incorporated only during the CP polymerization and thus limited to a single delivery. This work harnesses the record volume changes of a glycolated polythiophene p(g3T2) for controlled drug delivery. p(g3T2) undergoes reversible volumetric changes of up to 300% during electrochemical doping, forming pores in the nm-size range, resulting in a conducting hydrogel. p(g3T2)-coated 3D carbon sponges enable controlled loading and release of molecules spanning molecular weights of 800-6000 Da, from simple dyes up to the hormone insulin. Molecules are loaded as a combination of electrostatic interactions with the charged polymer backbone and physical entrapment in the porous matrix. Smaller molecules leak out of the polymer while larger ones could not be loaded effectively. Finally, this work shows the temporally patterned release of molecules with molecular weight of 1300 Da and multiple reloading and release cycles without affecting the on/off ratio.

  • 4. Abitbol, T.
    et al.
    Ahniyaz, A.
    Álvarez-Asencio, R.
    Fall, A.
    Swerin, Agne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Nanocellulose-Based Hybrid Materials for UV Blocking and Mechanically Robust Barriers2020In: ACS Applied Bio Materials, E-ISSN 2576-6422, Vol. 3, no 4, p. 2245-2254Article in journal (Refereed)
    Abstract [en]

    Nanocellulose (NC)-based hybrid coatings and films containing CeO2 and SiO2 nanoparticles (NPs) to impart UV screening and hardness properties, respectively, were prepared by solvent casting. The NC film-forming component (75 wt % of the overall solids) was composed entirely of cellulose nanocrystals (CNCs) or of CNCs combined with cellulose nanofibrils (CNFs). Zeta potential measurements indicated that the four NP types (CNC, CNF, CeO2, and SiO2) were stably dispersed in water and negatively charged at pH values between 6 and 9. The combination of NPs within this pH range ensured uniform formulations and homogeneous coatings and films, which blocked UV light, the extent of which depended on film thickness and CeO2 NP content, while maintaining good transparency in the visible spectrum (∼80%). The addition of a low amount of CNFs (1%) reduced the film hardness, but this effect was compensated by the addition of SiO2 NPs. Chiral nematic self-assembly was observed in the mixed NC film; however, this ordering was disrupted by the addition of the oxide NPs. The roughness of the hybrid coatings was reduced by the inclusion of oxide NPs into the NC matrix perhaps because the spherical oxide NPs were able to pack into the spaces between cellulose fibrils. We envision these hybrid coatings and films in barrier applications, photovoltaics, cosmetic formulations, such as sunscreens, and for the care and maintenance of wood and glass surfaces, or other surfaces that require a smooth, hard, and transparent finish and protection from UV damage.

  • 5.
    Abrahamsson, Tobias
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Synthetic Functionalities for Ion and Electron Conductive Polymers: Applications in Organic Electronics and Biological Interfaces2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the search for understanding and communicating with all biological systems, in humans, animals, plants, and even microorganisms, we find a common language of all communicating via electrons, ions and molecules. Since the discovery of organic electronics, the ability to bridge the gap and communicate be-tween modern technology and biology has emerged. Organic chemistry pro-vides us with tools for understanding and a material platform of polymer electronics for communication. Such insights give us not only the ability to observe fundamental phenomenon but to actively design and construct materials with chemical functionalities towards better interfaces and applications. Organic electronic materials and devices have found their way to be implemented in the field of medicine for diagnostic and therapeutic purposes, but also in water purification and to help tackle the monumental task in creating the next generation of sustainable energy production and storage. Ultimately it’s safe to say that organic electronics are not going to replace our traditional technology based on inorganic materials but rather the two fields can find a way to complement each other for various purposes and applications. Compared to conventional silicon based technology, production of carbon-based organic electronic polymer materials are extremely cheap and devices can even be made flexible and soft with great compatibility towards biology.  

    The main focus of this thesis has been developing and synthesizing new types of organic electronic and ionic conductive polymeric materials. Rational chemical design and modifications of the materials have been utilized to introduce specific functionalities to the materials. The functionalities serving the purpose to facilitate ion and electron conductive charge transport for organic electronics and with biological interface implementation of the polymer materials. 

    Multi-functional ionic conductive hyperbranched polyglycerol polyelectrolytes (dendrolytes) were developed comprising both ionically charged groups and cross-linkable groups. The hyperbranched polyglycerol core structure of the material possesses a hydrophilic solvating platform for both ions and maintenance of solvent molecules, while being a biocompatible structure. Coupled with the peripheral charged ionic functionalities of the polymer, the dendrolyte materials are highly ionic conductive and selective towards cationic and anionic charged atoms and large molecules when implemented as ion-exchange membranes. Homogenous ion-exchange membrane casting has been achieved by the implementation of cross-linkable functionalities in the dendrolytes, utilizing robust click-chemistry for efficient micro and macro fabrication processing of the ion-ex-change membranes for organic electronic devices. The ion-exchange membrane material was implemented in electrophoretic drug delivery devices (organic electronic ion pumps), which are used for delivery of ions and neurotransmitters with spatiotemporal resolution and are able to communicate and be used for therapeutic drug delivery purposes in biological interfaces. The dendrolyte materials were also able to form free-standing membranes, making it possible for implementation in fuel cell and desalination purposes. 

    Trimeric conjugated thiophene pre-polymer structures were also developed in the thesis and synthesized for the purpose of implementation of the material in vivo to form electrically conductive polymer structures, and in such manner to be able to create electrodes and ultimately to connect with the central nervous system. The conjugated pre-polymers being both water soluble and enzymatically polymerizable serve as a platform to realize such a concept. Also, modifying the trimeric structure with cross-linkable functionality created the capability to form better interfaces and stability towards biological environments.   

    Download full text (pdf)
    fulltext
    Download (png)
    presentationsbild
  • 6.
    Abrahamsson, Tobias
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Seitanidou, Maria S
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Roy, Arghyamalya
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Phopase, Jaywant
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Petsagkourakis, Ioannis
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Moro, Nathalie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Empa, Switzerland.
    Tybrandt, Klas
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Simon, Daniel
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Investigating the role of polymer size on ionic conductivity in free-standing hyperbranched polyelectrolyte membranes2021In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 223, article id 123664Article in journal (Refereed)
    Abstract [en]

    Polymer-based ion exchange membranes (IEMs) are utilized for many applications such as in water desalination, energy storage, fuel cells and in electrophoretic drug delivery devices, exemplified by the organic electronic ion pump (OEIP). The bulk of current research is primarily focused on finding highly conductive and stable IEM materials. Even though great progress has been made, a lack of fundamental understanding of how specific polymer properties affect ionic transport capabilities still remains. This leads to uncertainty in how to proceed with synthetic approaches for designing better IEM materials. In this study, an investigation of the structure-property relationship between polymer size and ionic conductivity was performed by comparing a series of membranes, based on ionically charged hyperbranched polyglycerol of different polymer sizes. Observing an increase in ionic conductivity associated with increasing polymer size and greater electrolyte exclusion, indi-cating an ionic transportation phenomenon not exclusively based on membrane electrolyte uptake. These findings further our understanding of ion transport phenomena in semi-permeable membranes and indicate a strong starting point for future design and synthesis of IEM polymers to achieve broader capabilities for a variety of ion transport-based applications.

    Download full text (pdf)
    fulltext
  • 7. Acharya, Shravan S.
    et al.
    Easton, Christopher D.
    McCoy, Thomas M.
    Spiccia, Leone
    Ohlin, C. André
    Umeå University, Faculty of Science and Technology, Department of Chemistry. School of Chemistry, Monash University, Clayton, Australia.
    Winther-Jensen, Bjorn
    Diverse composites of metal-complexes and PEDOT facilitated by metal-free vapour phase polymerization2017In: Reactive & functional polymers, ISSN 1381-5148, E-ISSN 1873-166X, Vol. 116, p. 101-106Article in journal (Refereed)
    Abstract [en]

    Abstract Oxidative polymerization for the manufacture of conducting polymers such as poly(3,4-ethylenedioxy-thiophene) has traditionally employed iron(III) salts. Demonstrated in this study is vapour phase polymerization of 3,4-ethylenedio- xythiophene using a metal-free oxidant, ammonium persulfate, leading to films with an estimated conductivity of 75 S/cm. Additionally, a route for embedding active transition metal complexes into these poly(3,4-ethylenedioxythiophene)/-poly(styrene-4-sulfonate) (PEDOT/PSS) films via vapour assisted complexation is outlined. Here, the vapour pressure of solid ligands around their melting temperatures was exploited to ensure complexation to metal ions added into the oxidant mixture prior to polymerization of PEDOT. Four composite systems are discussed, viz. PEDOT/PSS embedded with tris(8-hydroxyquinolinato)cobalt(III), tris(2,2-bipyridine)cobalt(II), tris(1,10- phenanthroline)cobalt(II) and tris(8-hyd-roxyquinolinato)aluminium(III). Using these composites, electrochemical reduction of nitrite to ammonia with a faradaic efficiency of 61% was reported.

  • 8. Adamus, Grazyna
    et al.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Höglund, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kowalczuk, Marek
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 6, p. 1540-1546Article in journal (Refereed)
    Abstract [en]

    Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by H-1 and C-13 NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.

  • 9.
    Adatia, Karishma K.
    et al.
    Institute of Interfacial Process Engineering and Plasma Technology Igvp, University of Stuttgart, Stuttgart, Germany; Department of Chemical Engineering, Stanford University, Stanford, CA, United States.
    Holm, Alexander
    Department of Chemical Engineering, Stanford University, Stanford, CA, United States.
    Southan, Alexander
    Institute of Interfacial Process Engineering and Plasma Technology Igvp, University of Stuttgart, Stuttgart, Germany.
    Frank, Curtis W.
    Department of Chemical Engineering, Stanford University, Stanford, CA, United States.
    Tovar, Günter E. M.
    Institute of Interfacial Process Engineering and Plasma Technology Igvp, University of Stuttgart, Stuttgart, Germany; Fraunhofer Institute for Interfacial Engineering and Biotechnology Igb, Stuttgart, Germany.
    Structure–property relations of amphiphilic poly(furfuryl glycidyl ether)-block-poly(ethylene glycol) macromonomers at the air–water interface2020In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 11, no 35, p. 5659-5668Article in journal (Refereed)
    Abstract [en]

    To deepen our knowledge of the film formation and the structure–property relations of poly(furfuryl glycidyl ether)-block-poly(ethylene glycol) (PFGEp-b-PEGq) macromonomers at the air–water interface, we synthesized PFGEp-b-PEGq in six different block lengths. The molar mass of the PFGEp-b-PEGq macromonomers varied from ∼2000 g mol−1 to ∼7000 g mol−1 and included a wide range of hydrophilic–lipophilic balance (HLB) values between 3.6 and 13.9. Surface pressure–area (πA) isotherms of these amphiphilic macromonomers revealed that the block lengths and the molar mass influence the isotherm shape and onset. Smaller, more hydrophobic macromonomers (HLB < 8) showed a steeper surface pressure increase in the liquid condensed phase compared to larger, more hydrophilic macromonomers with HLB > 8. The molecular area for isotherm onsets increased almost linearly with growing molar mass of the macromonomers. Static and dynamic film stability measurements demonstrated limited stability of all macromonomer monolayers at the air–water interface. The more hydrophilic macromonomers PFGE8-b-PEG79, PFGE18-b-PEG66 and PFGE13-b-PEG111 (HLB > 8) showed higher film stability compared to the more hydrophobic macromonomers (HLB < 8). Hysteresis experiments displayed an almost linear increase of the film degradation with rising HLB values of the macromonomers. Due to partial film recovery of our macromonomers, we propose an interplay between a reversible folding and an irreversible submersion mechanism for the macromonomer monolayers at the air–water interface. The molecular structure and the film forming ability of the macromonomers at the air–water interface indicate that they are promising surface functionalization reagents for materials formed from aqueous solutions, such as hydrogels. In this regard, PFGE10-b-PEG9 is the most promising hydrogel surface functionalization reagent, because it can introduce the highest number of functional groups per surface area.

  • 10. Adekunle, Kayode
    et al.
    Cho, Sung-Woo
    Patzelt, Christian
    Blomfeldt, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Skrifvars, Mikael
    Impact and flexural properties of flax fabrics and Lyocell fiber-reinforced bio-based thermoset2011In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 30, no 8, p. 685-697Article in journal (Refereed)
    Abstract [en]

    A bio-based thermoset resin was reinforced with flax fabrics and Lyocell fiber. The effect of different weave architectures was studied with four flax fabrics with different architectures: plain, twill (two different types), and dobby. The effect of the outer ply thickness was studied and characterized with flexural and impact testing. Composites manufactured with plain weave reinforcement had the best mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength were 280MPa, 32GPa, 250MPa, 25GPa, and 75 kJ/m (2), respectively. Reinforcements with twill-weave architecture did not impart appreciable flexural strength or flexural modulus even when the outer thickness was increased. Plain- and dobby (basket woven style)-weave architectures gave better reinforcing effects and the flexural properties increased with an increase in outer thickness. Water absorption properties of the composites were studied and it was observed that the hybridization with Lyocell fiber reduced the water uptake. Field-emission scanning electron microscopy was used to study the micro-structural properties of the composites.

  • 11.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Biobased Composites Prepared by Compression Molding with a Novel Thermoset Resin from Soybean Oil and a Natural-Fiber Reinforcement2010In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 116, no 3, p. 1759-1765Article in journal (Refereed)
    Abstract [en]

    Biobased composites were manufactured with a compression-molding technique. Novel thermoset resins from soybean oil were used as a matrix, and flax fibers were used as reinforcements. The air-laid fibers were stacked randomly, the woven fabrics were stacked crosswise (0/90 ), and impregnation was performed manually. The fiber/resin ratio was 60 : 40. The prepared biobased composites were characterized by impact and flexural testing. Scanning electron microscopy of knife-cut cross sections of the specimens was also done to investigate the fiber–matrix interface. Thermogravimetric analysis of the composites was carried out to provide indications of thermal stability. Three resins from soybean oil [methacrylated soybean oil, methacrylic anhydride modified soybean oil (MMSO), and acetic anhydride modified soybean oil] were used as matrices. The impact strength of the composites with MMSO resin reinforced with air-laid flax fibers was 24 kJ/m2, whereas that of the MMSO resin reinforced with woven flax fabric was between 24 and 29 kJ/m2. The flexural strength of the MMSO resin reinforced with air-laid flax fibers was between 83 and 118 MPa, and the flexural modulus was between 4 and 6 GPa, whereas the flexural strength of the MMSO resin reinforced with woven fabric was between 90 and 110 MPa, and the flexural modulus was between 4.87 and 6.1 GPa.

  • 12.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Preparation of biobased composites using novel thermoset polymers from soybean oil and a natural fibre reinforcement2009Conference paper (Other academic)
    Abstract [en]

    Health related issues, stringent environmental protection policies, search for cost effective and alternative materials, crave for renewability and sustainability and quest for high performance materials for structural applications give the motivation for research in polymer composites and material science. Due to the health, safety and environmental concerns over the conventional synthetic materials and the legislation against their usage both in domestic and industrial applications, alternatives sources that will be comparable in properties are being sought. There is an emerging market for biodegradable polymers which is expected to increase substantially in the coming years.[1] Preparation of Composites Airlaid and woven flax fibre mats were first treated with 4% sodium hydroxide solution for one hour and then washed with plenty of water. This was done in order to remove any residual impurities. The fibres were dried at room temperature for 24 hr and then dried in a vacuum oven for 1hr at a temperature of 105°С. The 8 sheets of the fibre were hand laid cross- wisely and the impregnation was done manually. The fibre/ resin ratio was about 60% to 40%. Methacrylated soybean oil, methacrylic anhydride and acetic anhydride modified soybean oil were the synthesized matrices used. The compression moulding was done at a temperature of 170°С for 5 min at 40bar. Characterisations The tensile testing was performed based on an ISO-test method for tensile tests on plastic materials. The Charpy impact strength of unnotched specimens was evaluated in accordance with ISO 179 using a Zwick test instrument and scanning electron microscopy analysis was done on the fractured specimens. The composites showed various mechanical properties, having impact strengths between 24 and 63 kJ/m² and tensile strength up to 51MPa.

  • 13.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthesis of reactive soybean oils for use as biobased thermoset resins in structural natural fibre composites2008Conference paper (Refereed)
  • 14.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthetic modification of reactive soybean oils for use as biobased thermoset resins in structural natural fiber composites2008Conference paper (Other academic)
  • 15.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthetic modification of reactive soybean oils for use as biobased thermoset resins in structural natural fiber composites2008In: Polymer Preprints, ISSN 0551-4657, Vol. 49, no 1, p. 279-Article in journal (Refereed)
  • 16.
    Afewerki, Samson
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Combined Catalysis: A Powerful Strategy for Engineering Multifunctional Sustainable Lignin-Based Materials2023In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 17, no 8, p. 7093-7108Article in journal (Refereed)
    Abstract [en]

    The production and engineering of sustainable materials through green chemistry will have a major role in our mission of transitioning to a more sustainable society. Here, combined catalysis, which is the integration of two or more catalytic cycles or activation modes, provides innovative chemical reactions and material properties efficiently, whereas the single catalytic cycle or activation mode alone fails in promoting a successful reaction. Polyphenolic lignin with its distinctive structural functions acts as an important template to create materials with versatile properties, such as being tough, antimicrobial, self-healing, adhesive, and environmentally adaptable. Sustainable lignin-based materials are generated by merging the catalytic cycle of the quinone-catechol redox reaction with free radical polymerization or oxidative decarboxylation reaction, which explores a wide range of metallic nanoparticles and metal ions as the catalysts. In this review, we present the recent work on engineering lignin-based multifunctional materials devised through combined catalysis. Despite the fruitful employment of this concept to material design and the fact that engineering has provided multifaceted materials able to solve a broad spectrum of challenges, we envision further exploration and expansion of this important concept in material science beyond the catalytic processes mentioned above. This could be accomplished by taking inspiration from organic synthesis where this concept has been successfully developed and implemented.

  • 17.
    Afewerki, Samson
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Engineering an All-Biobased Solvent- and Styrene-Free Curable Resin2023In: ACS Polymers Au, E-ISSN 2694-2453, Vol. 3, no 6, p. 447-456Article in journal (Refereed)
    Abstract [en]

    The sustainable production of polymers and materials derived from renewable feedstocks such as biomass is vital to addressing the current climate and environmental challenges. In particular, finding a replacement for current widely used curable resins containing undesired components with both health and environmental issues, such as bisphenol-A and styrene, is of great interest and vital for a sustainable society. In this work, we disclose the preparation and fabrication of an all-biobased curable resin. The devised resin consists of a polyester component based on fumaric acid, itaconic acid, 2,5-furandicarboxylic acid, 1,4-butanediol, and reactive diluents acting as both solvents and viscosity enhancers. Importantly, the complete process was performed solvent-free, thus promoting its industrial applications. The cured biobased resin demonstrates very good thermal properties (stable up to 415 °C), the ability to resist deformation based on the high Young’s modulus of ∼775 MPa, and chemical resistance based on the swelling index and gel content. We envision the disclosed biobased resin having tailorable properties suitable for industrial applications.

  • 18.
    Ahlinder, Astrid
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Charlon, Sebastien
    IMT Lille Douai, Ecole nationale supérieure Mines-Télécom Lille Douai, Materials & Processes Center, Cité scientifique, Villeneuve d'Ascq Cedex, France.
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Soulestin, Jeremie
    IMT Lille Douai, Ecole nationale supérieure Mines-Télécom Lille Douai, Materials & Processes Center, Cité scientifique, Villeneuve d'Ascq Cedex, France.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Minimise thermo-mechanical batch variations when processing medical grade lactide based copolymers in additive manufacturing2020In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 181, article id 109372Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing is suitable for producing complex geometries; however, variation in thermo-mechanical properties are observed during one batch cycle when degradable aliphatic polyesters of medical grade are used in melt extrusion-based methods. This is one important reason for why additive manufacturing has not yet been fully utilised to produce degradable medical implants. Herein, the internal variation has been minimised during one batch cycle by assessing the effect of different processing parameters when using commercially available medical grade copolymers. To minimise the molar mass, thermal and mechanical variation within one batch cycle, the rheological fingerprint of the commercially available medical grade poly(L-lactide-co-ε-caprolactone) and poly(L-lactide-co-trimethylene carbonate) has been correlated to the process parameters of the ARBURG Plastic Freeforming. An increase in the temperature up to 220°C and the associated increase in pressure are beneficial for the viscoelastic and thermally stable poly(L-lactide-co-ε-caprolactone). In contrast, a temperature below 220°C should be used for the poly(L-lactide-co-trimethylene carbonate) to reduce the variation in strain at break during one batch cycle. The residence time is decreased through the increase of the discharge parameter. An increase in temperature is however required to reduce the viscosity of the polymer and allow the pressure to stay within the machine limitations at higher discharge parameters. The results are highly relevant to the development of additive manufacturing for the production of degradable medical devices with identical properties. In fact, Food and Drug Administration guidelines for additive manufacturing of medical implants specify the need to control changes in material properties during the process.

  • 19.
    Ahlinder, Astrid
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Medical grade polylactide, copolyesters and polydioxanone: Rheological properties and melt stability2018In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 72, p. 214-222Article in journal (Refereed)
    Abstract [en]

    Rheological measurements have shown that lactide-based copolymers with L-lactide content between 50 and 100 mol% with varying comonomers, as well as polydioxanone (PDX), can be used in additive manufacturing analogously to poly(L-lactide) (PLLA) if their melt behaviour are balanced. The results indicate that copolymers can be melt processed if the temperature is adjusted according to the melting point, and parameters such as the speed are tuned to conteract the elastic response. Small amplitude oscillatory shear (SAOS) rheology, thermal and chemical characterisation allowed us to map the combined effect of temperature and frequency on the behaviour of six degradable polymers and their melt stability. Values of complex viscosity and Tan delta obtained through nine time sweeps by varying temperature and frequency showed that the molecular structure and the number of methylene units influenced the results, copolymers of L-lactide with D-Lactide (PDLLA) or glycolide (PLGA) had an increased elastic response, while copolymers with trimethylene carbonate (PLATMC) or epsilon-caprolactone (PCLA) had a more viscous behaviour than PLLA, with respect to their relative melting points. PDLLA and PLGA require an increased temperature or lower speed when processed, while PLATMC and PCLA can be used at a lower temperature and/or higher speed than PLLA. PDX showed an increased viscosity compared to PLLA but a similar melt behaviour. Negligible chain degradation were observed, apart from PLGA.

  • 20.
    Ahlström, Leon
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mattsson, Rebecca
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Eurén, Hampus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lidén, Alicia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Spruce bark biorefinery2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Spruce Bark contains several fundamental main substances; lignin, non-cellulose polysaccharides, cellulose and extractives. This undergraduate study focuses on developing a process to extract each of these components from spruce bark using a biorefinery concept, with a main focus on extracting lignin without degradation. The purpose of the Bark biorefinery concept is to contribute to a circular bioeconomy, by making use of natural resources. With extended research on the area, it will be possible to produce polymers, green chemicals and biofuel from the components in bark. 

    This report covers the extraction of the bark components with soxhlet extraction, Hot-water extraction, organosolv extraction and peracetic acid delignification. The extraction was made on two samples, matchstick-sized bark (MS) and 20 mesh-sized bark with a diameter of 0.8 mm (20M). The purpose was to be able to compare the efficiency of the extraction between the two samples. Afterwards, the characterisation of extracts and residue was executed with carbohydrate analysis, 2D HSQC-NMR and FTIR-analysis. 

    The results showed that a smaller particle size led to more efficient extractions of all components as well as more pure extract solutions. Lignin concentration determinations of samples at each step showed that a significant amount of lignin was lost prior to the organosolv extraction. Future research should look into ways to reduce this loss in order to increase the lignin yield. The findings in the FTIR and NMR analyses correlates with what could be seen in other reports, discussing similar subjects. For upscaling of this process, future research should go toward optimization of all extraction methods in order to make an upscaling of the process economically viable.  

    Download full text (pdf)
    fulltext
  • 21.
    Ahlsén, Jimmy
    et al.
    Perfomers of environmental monitoring, Companies, Marine Monitoring AB.
    Bergkvist, Johanna
    Perfomers of environmental monitoring, Companies, Marine Monitoring AB.
    Granmo, Åke
    Perfomers of environmental monitoring, Companies, Marine Monitoring AB.
    Undersökning av biota och sediment i anslutning till dumpningsområden av kemisk ammunition på väst- och östkusten 20192020Report (Other academic)
    Abstract [en]

    Marine Monitoring AB has by the request of the Swedish Agency for Marine and Water Management conducted an investigation about how widespread the contamination of dumped chemical warfare agents (CWAs) are in the dumping areas of Måseskär and the Gotland Basin. Earlier investigation in the area outside of Måseskär has shown traces of degradables from the CWAs Clark I and/or Clark II in biological samples. Sample fishing has been done in the eastern parts of the dumping area outside of Måseskär that has not previously been studied, as well as in the Gotland Basin wherein gas bombs has been visually identified. Chemical analyses were done by the Finnish Institute for Verification of the Chemical Weapons Convention, University of Helsinki (VERIFIN).

    Suitable target species were picked based on their commercial value and their ecology. On the west coast Norwegian lobsters, northern prawn and hagfish were captured and analysed. On the east coast cod and European flounder were captured and analysed. The sample fishing was conducted using passive gear such as cages, traps and nets. Sediment samples were also collected in the Gotland Basin.

    The results from the chemical analyses of the biological samples showed traces of CWA in the form of Clark I and/or Clark II as well as Arsine oil. Traces of CWA occurred in a bulk sample of hagfish caught downstream of the wreck BAL141 on the west coast and in two of the six bulk samples of cod captured in the Gotland Basin. All of the sediment samples contained traces of Clark I and/or Clark II in the form of diphenylarsinic acid (3O) and of Arsine oil in the form of triphenylarsine oxide (4O) as well as methylated forms of Adamsite (2.1) and Clark (3.1). The samples contained measurable concentrations however below the limits of quantitation.

    The risks of spreading of the content of the dumped CWAs rise as time passes because of corrosion of encapsulating shells. Natural currents lead to higher risks downstream of affected areas, something that can additionally worsen by bottom activities such as trawling in the area. All of the sediment samples taken in the Gotland Basin contained traces of CWAs which indicate that large sections of the area are contaminated. The same substances detected in the sediments were also found in the tissue of biological samples caught at the same locations. Affected biological samples have now for the first time been found within the territorial boarder at the dumping area on the west coast. This means a greater regulatory control from governmental agencies as to how the area will be used in the future.

    The low concentrations of Clark I and/or Clark II detected during earlier studies 2016 and 2017 as well as in the present study does not mean a greater health risk at consumption according to the Swedish National Food Agency (personal communication, Salomon Sand, Swedish Food Agency, Sweden). Presence of the compounds does however imply that they can accumulate in the tissues of biological samples in the studied areas. Traces of CWAs should not be present at all in the organisms, neither in the wild or on the dinner table.

    Download full text (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 22.
    Ahmed, Naeem
    et al.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Siow, Kim S.
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Wee, Mohd Farhanulhakim Mohd Razip
    Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia.
    Ho, Wai Kuan
    Crops for Future, Jln Broga, Semenyih 43500, Selangor, Malaysia.
    Patra, Anuttam
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    The Hydrophilization and Subsequent Hydrophobic Recovery Mechanism of Cold Plasma (CP) Treated Bambara Groundnuts2022In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 1055, p. 161-169Article in journal (Refereed)
    Abstract [en]

    Plasma hydrophilization and subsequent hydrophobic recovery in Bambara groundnuts are studied for the first time. Bambara groundnut seeds were treated with cold plasma (CP) for 10 seconds at 10 watts using water as a monomer. The contact angle, as well as physical and chemical changes, were used to determine the kinetics of hydrophobic recovery. The hydrophilic state of Bambara groundnut seeds had decreased after 60 days, but not to original hydrophobicity, and also the recovery rate is slower than those observed on synthetic polymer. However, this slower hydrophobic recovery makes CP treatment as an effective method for long-term seed storage.

  • 23. Ait Benhamou, Anass
    et al.
    Boukind, Soumia
    Khalili, Houssine
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Moubarik, Amine
    El Achaby, Mounir
    Kassab, Zineb
    Sehaqui, Houssine
    Strong and Flame-Resistant Nanocellulose Sheets Derived from Agrowastes via a Papermaking-Assisted Process2024In: acs applied polymer materials, ISSN 2637-6105, Vol. 6, no 5, p. 2763-2776Article in journal (Refereed)
    Abstract [en]

    In recent decades, the production of nanocellulose has gained significant attention. Nanocellulose-based film materials have found widespread applications in various high-end sectors owing to their remarkable characteristics. Nevertheless, the limitation of certain functional properties, such as resistance to water and fire, has posed challenges to their broader utilization. In this study, we conducted a comparative investigation on the impact of two distinct chemical modifications, namely, TEMPO-mediated oxidation and phosphorylation, on the production of nanocellulose sheets via a papermaking-assisted process. This approach explores the synergistic effects of these modifications in enhancing the properties of cellulose nanofibers for nanopaper production. To achieve this, we proposed utilizing Henna stems as an alternative source of cellulosic material, aiming to harness untapped agricultural residues as a sustainable alternative to conventional sources such as wood and cotton. The phosphorylated Henna nanopaper exhibited substantial enhancements in terms of mechanical properties, wettability, fire resistance, and water vapor permeability when compared to the TEMPO-modified Henna nanopaper. In conclusion, our findings underscore the potential of Henna stems as an environmentally sustainable source of cellulose for nanofiber production, positioning it as a promising alternative to wood and other lignocellulosic sources for advanced applications.

  • 24.
    Ajalloueian, Fatemeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Zeiai, S.
    Fossum, M.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    A bedside collagen-PLGA nanofibrous construct for autologous transplantation of minced bladder mucosal2012In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, Vol. 6, no suppl 1, p. 128-128Article in journal (Other academic)
    Abstract [en]

    Introduction: Bladder regeneration using minced bladder mucosa is an alternative to costly and time-consuming conventional in vitro culturing of urothelial cells. In this method, the uroepithelium expands in vivo and the patient body appears as an incubator. With our preliminary successes, designing an appropriate scaffold that supports in vivo cell expansion and surgical handling in a clinical setting was our aim. This study, investigates cell expansion in a hybrid construct of collagen/poly (lactic-co-glycolide)(PLGA).

    Materials and methods: An electrospun PLGA mat was placed on a semi-gel collagen inside a mold and covered with a second collagen layer. After gel formation, minced particles of pig bladder mucosa were seeded on the hybrid construct and then processed by plastic compression (PC). The scaffolds were incubated for 2, 4 and 6 weeks in vitro for further studies.

    Results: Tensile tests show an increase in tensile strength of 0.6 ± 0.1 MPa in PC collagen to 3.6 ± 1.1 MPa in hybrid construct. Morphological studies, histological staining and SEM show that the construct has kept its integrity during the time and proliferated urothelial cells have reached confluence after 4 weeks and a multi-layered urothelium after 6 weeks.

    Conclusion: We have designed a mechanically robust scaffold that permits surgical handling and tissue expansion in vivo. The construct is easy-to-use for clinical application in an ordinary surgical operating theater for bladder regeneration.

  • 25.
    Ajjan, Fátima
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ambrogi, Martina
    Max Planck Institute Colloids and Interfaces, Germany.
    Ayalneh Tiruye, Girum
    IMDEA Energy Institute, Spain.
    Cordella, Daniela
    University of Liege ULg, Belgium.
    Fernandes, Ana M.
    POLYMAT University of Basque Country UPV EHU, Spain.
    Grygiel, Konrad
    Max Planck Institute Colloids and Interfaces, Germany.
    Isik, Mehmet
    POLYMAT University of Basque Country UPV EHU, Spain.
    Patil, Nagaraj
    University of Liege ULg, Belgium.
    Porcarelli, Luca
    POLYMAT University of Basque Country UPV EHU, Spain.
    Rocasalbas, Gillem
    KIOMedPharma, Belgium.
    Vendramientto, Giordano
    University of Bordeaux, France.
    Zeglio, Erica
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Antonietti, Markus
    Max Planck Institute Colloids and Interfaces, Germany.
    Detrembleur, Cristophe
    University of Liege ULg, Belgium.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jerome, Christine
    University of Liege ULg, Belgium.
    Marcilla, Rebeca
    IMDEA Energy Institute, Spain.
    Mecerreyes, David
    POLYMAT University of Basque Country UPV EHU, Spain; Basque Fdn Science, Spain.
    Moreno, Monica
    POLYMAT University of Basque Country UPV EHU, Spain.
    Taton, Daniel
    University of Bordeaux, France.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yuan, Jiayin
    Max Planck Institute Colloids and Interfaces, Germany.
    Innovative polyelectrolytes/poly(ionic liquid)s for energy and the environment2017In: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 66, no 8, p. 1119-1128Article, review/survey (Refereed)
    Abstract [en]

    This paper presents the work carried out within the European project RENAISSANCE-ITN, which was dedicated to the development of innovative polyelectrolytes for energy and environmental applications. Within the project different types of innovative polyelectrolytes were synthesized such as poly(ionic liquid)s coming from renewable or natural ions, thiazolium cations, catechol functionalities or from a new generation of cheap deep eutectic monomers. Further, macromolecular architectures such as new poly(ionic liquid) block copolymers and new (semi)conducting polymer/polyelectrolyte complexes were also developed. As the final goal, the application of these innovative polymers in energy and the environment was investigated. Important advances in energy storage technologies included the development of new carbonaceous materials, new lignin/conducting polymer biopolymer electrodes, new iongels and single-ion conducting polymer electrolytes for supercapacitors and batteries and new poly(ionic liquid) binders for batteries. On the other hand, the use of innovative polyelectrolytes in sustainable environmental technologies led to the development of new liquid and dry water, new materials for water cleaning technologies such as flocculants, oil absorbers, new recyclable organocatalyst platforms and new multifunctional polymer coatings with antifouling and antimicrobial properties. All in all this paper demonstrates the potential of poly(ionic liquid)s for high-value applications in energy and enviromental areas. (c) 2017 Society of Chemical Industry

  • 26.
    Akbari, Samira
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Root, Andrew
    MagSol, Tuhkanummenkuja 2, 00970, Helsinki, Finland.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Novel Bio-based Branched Unsaturated Polyester Resins for High-Temperature Applications2023In: Journal of Polymers and the Environment, ISSN 1566-2543, E-ISSN 1572-8919Article in journal (Refereed)
    Abstract [en]

    Unsaturated polyester resins, one of the most important thermosets, are invariably produced from oil-based monomers. Their application is limited in areas where high thermal stability is required due to their low Tg. Besides, these resins contain 30–40% hazardous styrene as a reactive solvent. Therefore, developing bio-based solventless unsaturated polyester resin with medium to high thermomechanical properties compared to petrochemical-based counterparts is important. In order to achieve this, a series of branched bio-based unsaturated polyester resins were synthesized using bulk polymerization method in two steps. In the first step, four different intermediates were prepared by reacting glycerol (as a core molecule) with either isosorbide (diol), 1,3-propanediol (diol), 2,5-furandicarboxylic acid (saturated diacid), or adipic acid (saturated diacid). In the second step, the branched intermediate was end capped with methacrylic anhydride to introduce reactive sites for cross-linking on the branch ends. The chemical structure of the resins was characterized by 13C-NMR. FT-IR confirmed the polycondensation reaction in the first step and the end functionalization of the resins with methacrylic anhydride in the second step. The effect of 2,5-furandicarboxylic acid and isosorbide on thermomechanical and thermal properties was investigated using dynamic mechanical analysis, differential scanning calorimetry, and thermo-gravimetric analysis. Results indicated that 2,5-furandicarboxylic acid based resins had superior thermomechanical properties compared to a commercial reference unsaturated polyester resin, making them promising resins for high-temperature composite applications. For example, the resin based on 2,5-furandicarboxylic acid and isosorbide and the resin based on 2,5-furandicarboxylic acid and 1,3-propanediol gave glass transition temperatures of 173 °C and 148 °C, respectively. Although the synthesized 2,5-furandicarboxylic acid based resins had higher viscosity (22.7 Pas) than conventional unsaturated polyester (0.4–0.5 Pas) at room temperature, preheated resins can be used for making high-temperature-tolerance fiber-reinforced composite. 

    Download full text (pdf)
    fulltext
  • 27.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Brana, M. T. Conde
    Bellander, M.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel2015In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 111, p. 211-222Article in journal (Refereed)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR) exposed to rapeseed biodiesel at 90 degrees C was studied. The oxidation of biodiesel and NBR during ageing was monitored by H-1 NMR and infrared spectroscopy, HPLC and titration methods. The oxidation of biodiesel was impeded in the presence of NBR, but promoted in biodiesel-exposed rubber. This was explained as being due to the migration of stabilizer from the rubber to biodiesel, the diffusion of dissolved oxygen from biodiesel into NBR and the absorption of oxidation precursors of biodiesel by the rubber. The resemblance between the anomalous sorption kinetics of biodiesel in NBR and the equilibrium benzene uptake by the aged rubbers revealed that biodiesel caused a network defect in NBR, resulting in a gradual increase in the equilibrium swelling. The cleavage of crosslinks was implausible since the Young's modulus of the rubber at low strains, disregarding an initial decrease, increased with increasing exposure time. The appearance of 'naked' carbon black particles in the scanning electron micrographs of the aged rubbers and a drastic decrease in the strain-at-break of NBR after exposure to biodiesel suggests that internal cavitation was caused by the attack of biodiesel on the acrylonitrile units of NBR.

  • 28.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Pourrahimi, Amir Masoud
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Sjöstedt, C.
    Bellander, M.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Degradation of carbon-black-filled acrylonitrile butadiene rubber in alternative fuels: Transesterified and hydrotreated vegetable oils2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 123, p. 69-79Article in journal (Refereed)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR), a common sealing material in automobile fuel systems, when exposed to rapeseed biodiesel and hydrotreated vegetable oil (HVO) was studied. The fuel sorption was hindered in HVO-exposed rubber by the steric constraints of bulky HVO molecules, but it was promoted in biodiesel-exposed rubber by fuel-driven cavitation in the NBR and by the increase in diffusivity of biodiesel after oxidation. The absence of a tan δ peak of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was made possible in biodiesel-aged rubber by the detachment of bound rubber from particle surfaces. The HVO-exposed NBR showed a small decrease in strain-at-break due to the migration of plasticizer from the rubber, and a small increase in the Young’s modulus due to oxidative crosslinking. A drastic decrease in extensibility and Payne-effect amplitude of NBR on exposure to biodiesel was explained as being due to the damage caused by biodiesel to the continuous network of bound rubber-carbon black. A decrease in the ZnO crystal size with increasing exposure time suggested that the particles are gradually dissolved in the acidic components of oxidized biodiesel. The Zn2+ cations released from the dissolution of ZnO particles in biodiesel promoted the hydrolysis of the nitrile groups of NBR.

  • 29.
    Albertsson, Ann-Christine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Celebrating 20 years of Biomacromolecules!2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 767-768Article in journal (Refereed)
  • 30.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Long-Term Properties of Polyolefins2004Collection (editor) (Refereed)
    Abstract [en]

    We dedicate the current volume entitled "Long-Term Properties of Polyolefins"to Professor Kausch on his 25th anniversary as editor of Advances in PolymerScience. Professor Kausch pioneered the work on molecular effects in thefracture of polymers. This is beautifully summarized in his books on polymerfracture. Professor Kausch is also the perfect gentleman - always eager to helpnewcomers to make their entrance into the scientific community and to assisthis colleagues in their work and accomplishments. With his work, ProfessorKausch has demonstrated the importance of "source science" - to present newdata - and to present reviews of previously published material. This book ispresented in the spirit of Professor Kausch, namely showing a good selection ofdata and explaining what they mean.The main focus of this book is the relation between structure and propertiesand the trend towards better quality and reproducibility. The first chapterdescribes the metallocene polymerisation catalysts and their possihility notonly of tailoring polymer properties but also of manufacturing entirely newmaterials. Due to improved control of microstructure, it will also be possible toproduce specialty polyolefins which could compete with non-olefinic polymers.The next chapter shows how in each new development step catalyst and processinnovations have gone hand in hand and how the control over polymer structureand the ability to tailor material properties has increased. For a betterunderstanding of properties and behaviour, the basic of morphology is fundamentaland is described in chapter three, followed by chapter four aboutfracture properties and microdeformation behaviour. Promising model systemsfor the investigations of the relations between crack-tip deformation, fractureand molecular structure are also presented. Chapter five gives an overviewof stabilization of polyethylene crucial for long-term properties. Two mainapproaches have been used; the first advocates the use of biological antioxidants,and the second relies on the use of reactive antioxidants that are chemicallyattached onto the polymer backbone for greater performance and safety.Chemiluminescence is presented as a too1 for studying the initial stages inoxidative degradation and is explained in chapter six. However, for many years,tailor-made structures specially designed for environmental degradation havealso been a reality. One of the key questions for successhl development and useof environmentally degradable polymers is the interaction between the degradationprodncts and nature and this is illustrated in chapter seven. The developmentof chromatographic methods and use of chromatographic fingerprintinggives not only degradation products bnt also information about degradationmechanisms as well as interaction between the polymer and different environments.The obstacles and possibilities for recycling of polyolefins are discussedin chapter eigbt with special emphasis on analytical methods useful in theqnality concept. It is also shown how recycled material could be a valuable resourcein the Future together with renewable resources. Finally, chapter ninegives examples of existing as we11 as emerging techniques of surface modificationof polyethylene.These chapters together will hopefuiiy inspire to a new generation of polyethyleneby mimicking nature and use of new molecular architecture, newmorphology and also "activated" additives in microdomains, with even morereproducible properties within oarrow limits and with predetermined lifetimes.

  • 31.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    New matrices for controlled drug delivery.2000In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, American Chemical Society (ACS), 2000Conference paper (Refereed)
  • 32.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Novel release systems from biodegradable polymers1998In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, American Chemical Society (ACS), 1998Conference paper (Refereed)
  • 33.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Källrot, Martina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Surface modification of degradable polymers2005In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, American Chemical Society (ACS), 2005Conference paper (Refereed)
  • 34.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Varma, Indra Kumari
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Synthesis, Chemistry and Properties of Hemicelluloses2011In: Biopolymers: New Materials for Sustainable Films and Coatings / [ed] David Plackett, Chichester: John Wiley & Sons, 2011, 1, p. 135-150Chapter in book (Other academic)
  • 35.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradable polymers with tailored properties for biomedical materials2009In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 238Article in journal (Other academic)
  • 36.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Groning, M.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Emission of volatiles from polymers - A new approach for understanding polymer degradation2006In: Journal of Polymers and the Environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 14, no 1, p. 8-13Article in journal (Refereed)
    Abstract [en]

    Emission of low molar mass compounds from different polymeric materials was determined and the results from the volatile analysis were applied to predict the degree of degradation and long-term properties, to determine degradation rates and mechanisms, to differentiate between biotic and abiotic degradation and for quality control work. Solid-phase microextraction and solid-phase extraction together with GC-MS were applied to identify and quantify the low molar mass compounds. Volatiles were released and monitored at early stages of degradation before any matrix changes were observed by e.g. SEC, DSC and tensile testing. The analysis of volatiles can thus also be applied to detect small differences between polymeric materials and their susceptibility to degradation. The formation of certain degradation products correlated with the changes taking place in the polymer matrix, these indicator products could, thus, be analysed to rapidly predict the degree of degradation in the polymer matrix and further to predict the long-term properties and remaining lifetime of the product.

  • 37.
    Albertsson, Ann-Christine
    et al.
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    The influence of biotic and abiotic environments on the degradation of polyethylene1990In: Progress in polymer science, ISSN 0079-6700, E-ISSN 1873-1619, Vol. 15, no 2, p. 177-192Article in journal (Refereed)
  • 38.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Kumari Varma, Indra
    Centre for Polymer Science and Engineering, Indian Institute of Technology, New Dehli, India.
    Srivastava, Rajiv K.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Polyesters from Large Lactones2009In: Handbook of Ring-Opening Polymerization / [ed] Philippe Dubois, Olivier Coulembier, Jean-Marie Raquez, Wiley-VCH Verlagsgesellschaft, 2009, 1, p. 287-306Chapter in book (Other academic)
  • 39.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Källrot, Martina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    POLY 585-Covalent surface modification of degradable polymers2007In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Article in journal (Other academic)
  • 40.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Controlled synthesis of star-shaped homo- and co-polymers of aliphatic polyesters2006In: 7th International Biorelated Polymers Symposium, 2006, p. 37-38Conference paper (Refereed)
    Abstract [en]

    The challenges in finding a material with the proper characteristics for a given tissue engineering application are several. One solution is improving the ability to tailor the mechanical and physical properties along with the degradation profile of aliphatic polyesters, by for example alterations in their composition and architecture. In this study, well-defined star-shaped aliphatic polyesters constituted of four arms were synthesized. As a model system, L,L-lactide and a spirocyclic tin initiator was chosen and the affect of the solvent, temperature and monomer-to-initiator ratio on the number average molecular weight, the molecular weight distribution and the conversion of the polymers was shown. Consecutively, we proved that well-defined star-shaped block copolymers composed of 1,5-dioxepan-2-one and L,L-lactide with narrow molecular weight distributions and controlled block lengths can be synthesized using this system.

  • 41.
    Albertsson, Ann-Christine
    et al.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Olander, Björn
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Edlund, Ulrica
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Källrot, Martina
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Increased biocompatibility by surface modification2004In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 228, p. U508-U508Article in journal (Other (popular science, discussion, etc.))
  • 42.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Percec, Simona
    Future of Biomacromolecules at a Crossroads of Polymer Science and Biology2020In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 21, no 1, p. 1-6Article in journal (Refereed)
  • 43.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Varma, Indra Kumari
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Lochab, Bimlesh
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Finne Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Kumar, Kamlesh
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Design and Syntesis of Different Types of Poly(Lactic acid)2010In: Poly(Lactic Acid): Synthesis, Structures, Properties, Processing and Applications / [ed] Rafael Auras, Loong-Tak Lim, Susan E. M. Selke, Hideto Tsuji, John Wiley & Sons, 2010, p. 43-58Chapter in book (Other academic)
  • 44.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Varma, Indra Kumari
    Centre for Polymer Science and Engineering, Indian Institute of Technology, New Delhi, India.
    Lochab, Bimlesh
    Materials Research Laboratory, Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Greater Noida, India.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sahu, Sangeeta
    Materials Research Laboratory, Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Tehsil Dadri, India.
    Kumar, Kamlesh
    Council of Scientific and Industrial Research, Central Scientific Instruments Organization, Chandigarh, India.
    Design and synthesis of different types of poly(lactic acid)/polylactide copolymers2022In: Poly(lactic acid): Synthesis, Structures, Properties, Processing, Applications, and End of Life, Wiley , 2022, p. 45-71Chapter in book (Other academic)
    Abstract [en]

    High molar mass poly(lactic acid) (PLA) is obtained by either the polycondensation of lactic acid or ring-opening polymerization (ROP) of the cyclic dimer 2,6-dimethyl-1,4-dioxane-2,5-dione, commonly referred to as dilactide or lactide (LA). This chapter describes preparation of polymers and copolymers of LAs with different structures, using polycondensation and ROP. Typical comonomers and polymers which are used for lactic acid or LA copolymerization include glycolic acid or glycolide, poly(ethylene glycol) or poly(ethylene oxide), and so on. PLAs having amino, carboxyl, or other functional groups are well reported in the literature. These functional groups can be utilized for chemical modification or as binding sites for biomolecules to impart selective binding and adhesion. PLA and its copolymers especially when used for biological applications, besides requirement of optimization of mechanical properties by engineering at the molecular level, also demands a fast degradation polymer rate.

  • 45.
    Albinsson, Emmy
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Tafesse Belachew, Helina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Swaich, Jasmin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Juhlin, Hannah
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Novel materials from lignocellulosic sources- can they replace thermoplastics?2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Plastic waste is a severe environmental problem in today's society which has been noticed and discussed during the last couple of years. A constant increase of production over the last decades hasled to a large amount of plastic waste ending up in oceans as microplastics. With harder restrictions of plastic use from the European Parliament, alternative plastics that are bio-based and therefore degradable have increased in demand. The aim of this project was therefore to synthesize alignocellulose-based material which contains the minimum amount of latex, the plastic component, while still satisfying the same requirements as a thermoplastic. The original idea was to create the latex with PISA-RAFT technique however, this was not possible since the needed materials could not be delivered due to COVID-19, therefore radical emulsion polymerization was carried out.

    Two latexes were synthesized to create composites with wheat-straw, latex A and latex B. Both latexes consisted of 75% of monomer vinyl acetate (VAc) which was the main component but with different weight percentages of monomers methacrylic acid (MAA) and methyl methacrylate (MMA). Latex A consisted of 20 % MAA and 5% MMA and latex B consisted of 20% MMA and 5% MAA. Latex A and latex B were then mixed with wheat straw to create composites. Due to problems withthe wheat-straw composites one additional composite was created to be able to do all of the analyses. This composite was created by using filter paper as biofiber to mix with the two different latexes. Various characterization analyses including FE-SEM, DLS, DSC, FTIR, NMR, TGA and tensile tests were performed on the composites.

    The NMR and DSC analyses indicated that the actual composition of monomers differs from the theoretical composition and demonstrates that the presence of MAA is hard to detect. This is due to the DSC value for latex A experimental Tg being lower than latex B experimental Tg when latex A consists of more MAA which has a higher detected Tg. During the NMR analysis MAA was also not detected in either latex A nor latex B. The analyses of FTIR contradicts the NMR and DSC analyses hence peaks believed to be from MAA are detected. When comparing the analysis for latex A and B, DLS analysis resulted in latex A having a low PDI and a bigger emulsion sphere size which is preferred when producing composites. The tensile test resulted in latex B achieving the higher values for Young’s modulus and max stress while latex A had a higher value for strain at break. The TGA and DSC analysis however resulted in latex B having a higher Tg and higher thermal stability. The overall analyses indicated that latex B was the most optimal choice for composite production with aslight difference.

    The analysis of the composites indicated by FE-SEM that the interaction between latex and filter paper were higher than for latex and wheat straw. A total of four wheat-straw composites were created with the weight-ratio of wheat-straw:latex, 50:50 and 75:50 for both latex A and B. Due to not being able to grind the wheat straw to the minimum size needed to create composites only FE-SEM and FTIR analyses of the wheat-straw composites could be made. Because of this no conclusion could be made whether the 75:50 or 50:50 weight ratio was the most optimal.

    Download full text (pdf)
    fulltext
  • 46.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University.
    de Wit, Paul P.
    AkzoNobel Specialty Chemicals.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Variation of the alkalisation conditions during the synthesis of a cellulose etherManuscript (preprint) (Other academic)
    Abstract [en]

    We show the effect of simultaneous variation of i) the NaOH/AGU (anhydroglucose unit) stoichiometric ratio (r), ii) added [NaOH], and iii) mercerization time, on the degree of cellulose substitution (DS), and by-product formation including proportions of insoluble particles and unreacted chemicals, in the synthesis of carboxymethylcellulose (CMC), under conditions resembling those often used for production of non-ionic cellulose ethers and without the use of alcohols. The DS was found to increase when (r) was increased (range 1.0-1.3) and added [NaOH] was decreased (range 50-30%). However, such changes also favoured the formation of unwanted by-products. Decreased (r) and increased [NaOH] resulted in increased the quantities of insoluble particles and unreacted chemicals. In the CMC samples, DS of 0.18-0.7 was obtained. The measured solubility (46%-86%) was lower than expected for a given DS. This, along with a deviation of the substituent distribution from the statistical calculations, indicated a high heterogeneity in the samples. The substitution at hydroxyl positions within the AGU shows the order of < ≈ , and that substitution increases with (r). The relative importance of substitution at increases with an increased [NaOH].

  • 47.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 2, p. 1061-1072Article in journal (Refereed)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

    Download full text (pdf)
    fulltext
  • 48.
    Alexakis, Alexandros Efraim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Nanolatexes: a versatile toolbox for cellulose modification2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cellulosic materials are widely used in our everyday lives, ranging from paperand packaging to biomedical applications. However, in most applications, cellulose must coexist with hydrophobic polymers which can be challenging due to its hydrophilic character. This has encouraged the exploration of chemical and physical modifications of cellulose.

    The projects included in this thesis focus on the physical modification of cellulosic materials with tailor-made, highly versatile colloidal nanoparticles synthesized in water, called nanolatexes. Their synthesis is based on the combination of the reversible addition-fragmentation chain transfer (RAFT) polymerization with polymerization-induced self-assembly (PISA). The bridging of these techniques results in the formation of amphiphilic diblock copolymers which self-assemble in water forming a variety of morphologies. Spheres, worms and vesicles with pH-responsive shell polymers were prepared to investigate the parameters that tune these morphological transitions. Less investigated parameters such as the chemical composition of the RAFT agent were studied which resulted in the formation of bimodal nanolatexes with opal-like characteristics in a reproducible manner. 

    A fundamental investigation of the parameters that govern the adsorption of cationically charged nanolatexes onto silica and regenerated TEMPO-oxidized cellulose model surfaces was also performed. The combination of gravimetric and a reflectometric techniques revealed the complexity of that model surface. Both the size and the charge density of the nanolatexes were found to influence their adsorption. The information gained from this study was implemented in the preparation of cellulose nanofibril (CNF)-nanocomposites with low contents of nanolatexes. It was found that when the nanolatex content was below 1 wt% the mechanical profile of the CNF-nanocomposites was improved. 

    Finally, wood-based components were used to replace fossil-based monomers in nanolatexes. They were readily adsorbed onto cellulose filter papers and annealed, thus demonstrating their film formation capacity. Nanolatexes comprised of a wood-based shell polymer have a promising high-end application profile, as showcased by their interactions with Cu(II) ions, where nanolatexes prevented the formation of Cu(II) ion aggregates. 

    The results summarized in this thesis add to the understanding on physical modification of cellulose and are envisaged to further promote the utilization of wood-based monomers in the production of the polymers for high-end applications.

    Download full text (pdf)
    fulltext
  • 49.
    Alexakis, Alexandros Efraim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ayyachi, Thayanithi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Mousa, Maryam
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Olsen, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    2-Methoxy-4-Vinylphenol as a Biobased Monomer Precursor for Thermoplastics and Thermoset Polymers2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 9, article id 2168Article in journal (Refereed)
    Abstract [en]

    To address the increasing demand for biobased materials, lignin-derived ferulic acid (FA) is a promising candidate. In this study, an FA-derived styrene-like monomer, referred to as 2-methoxy-4-vinylphenol (MVP), was used as the platform to prepare functional monomers for radical polymerizations. Hydrophobic biobased monomers derived from MVP were polymerized via solution and emulsion polymerization resulting in homo- and copolymers with a wide range of thermal properties, thus showcasing their potential in thermoplastic applications. Moreover, divinylbenzene (DVB)-like monomers were prepared from MVP by varying the aliphatic chain length between the MVP units. These biobased monomers were thermally crosslinked with thiol-bearing reagents to produce thermosets with different crosslinking densities in order to demonstrate their thermosetting applications. The results of this study expand the scope of MVP-derived monomers that can be used in free-radical polymerizations toward the preparation of new biobased and functional materials from lignin.

  • 50.
    Alexakis, Alexandros Efraim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Engström, Joakim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Stamm, Arne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Riazanova, Anastasia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Wallenberg Wood Sci Ctr WWSC, Tekn Ringen 56-58, SE-10044 Stockholm, Sweden..
    Brett, Calvin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, Hamburg, 22603, Germany.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, Hamburg, 22603, Germany.
    Syrén, Per-Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fogelström, Linda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Reid, Michael S.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Modification of cellulose through physisorption of cationic bio-based nanolatexes - comparing emulsion polymerization and RAFT-mediated polymerization-induced self-assembly2021In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 23, no 5, p. 2113-2122Article in journal (Refereed)
    Abstract [en]

    The polymerization of a bio-based terpene-derived monomer, sobrerol methacrylate (SobMA), was evaluated in the design of polymeric nanoparticles (nanolatexes). Their synthesis was accomplished by using emulsion polymerization, either by free-radical polymerization in the presence of a cationic surfactant or a cationic macroRAFT agent by employing RAFT-mediated polymerization-induced self-assembly (PISA). By tuning the length of the hydrophobic polymer, it was possible to control the nanoparticle size between 70 and 110 nm. The average size of the latexes in both wet and dry state were investigated by microscopy imaging and dynamic light scattering (DLS). Additionally, SobMA was successfully copolymerized with butyl methacrylate (BMA) targeting soft-core nanolatexes. The comparison of the kinetic profile of the cationically stabilized nanolatexes highlighted the differences of both processes. The SobMA-based nanolatexes yielded high T-g similar to 120 degrees C, while the copolymer sample exhibited a lower T-g similar to 50 degrees C, as assessed by Differential Scanning Calorimetry (DSC). Thereafter, the nanolatexes were adsorbed onto cellulose (filter paper), where they were annealed at elevated temperatures to result in polymeric coatings. Their morphologies were analysed by Field Emission Scanning Electron Microscopy (FE-SEM) and compared to a commercial sulfate polystyrene latex (PS latex). By microscopic investigation the film formation mechanism could be unravelled. Water contact angle (CA) measurements verified the transition from a hydrophilic to a hydrophobic surface after film formation had occured. The obtained results are promising for the toolbox of bio-based building blocks, focused on sobrerol-based monomers, to be used in emulsion polymerizations either for tailored PISA-latexes or facile conventional latex formation, in order to replace methyl methacrylate or other high T-g-monomers.

1234567 1 - 50 of 1936
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf