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  • 1.
    Aaen, Ragnhild
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Lehtonen, Mari
    University of Helsinki, Finland.
    Mikkonen, Kirsi
    University of Helsinki, Finland.
    Syverud, Kristin
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign. NTNU Norwegian University of Science and Technology, Norway.
    Combining cellulose nanofibrils and galactoglucomannans for enhanced stabilization of future food emulsions2021Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 28, nr 16, s. 10485-10500Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of wood-derived cellulose nanofibrils (CNFs) or galactoglucomannans (GGM) for emulsion stabilization may be a way to obtain new environmentally friendly emulsifiers. Both have previously been shown to act as emulsifiers, offering physical, and in the case of GGM, oxidative stability to the emulsions. Oil-in-water emulsions were prepared using highly charged (1352 ± 5 µmol/g) CNFs prepared by TEMPO-mediated oxidation, or a coarser commercial CNF, less charged (≈ 70 µmol/g) quality (Exilva forte), and the physical emulsion stability was evaluated by use of droplet size distributions, micrographs and visual appearance. The highly charged, finely fibrillated CNFs stabilized the emulsions more effectively than the coarser, lower charged CNFs, probably due to higher electrostatic repulsions between the fibrils, and a higher surface coverage of the oil droplets due to thinner fibrils. At a constant CNF/oil ratio, the lowest CNF and oil concentration of 0.01 wt % CNFs and 5 wt % oil gave the most stable emulsion, with good stability toward coalescence, but not towards creaming. GGM (0.5 or 1.0 wt %) stabilized emulsions (5 wt % oil) showed no creaming behavior, but a clear bimodal distribution with some destabilization over the storage time of 1 month. Combinations of CNFs and GGM for stabilization of emulsions with 5 wt % oil, provided good stability towards creaming and a slower emulsion destabilization than for GGM alone. GGM could also improve the stability towards oxidation by delaying the initiation of lipid oxidation. Use of CNFs and combinations of GGM and CNFs can thus be away to obtain stable emulsions, such as mayonnaise and beverage emulsions. © 2021, The Author(s).

  • 2.
    Abbadessa, Anna
    et al.
    KTH Royal institute of Technology, Sweden.
    Dogaris, Ioannis
    KTH Royal institute of Technology, Sweden.
    Kishani Farahani, Saina
    KTH Royal institute of Technology, Sweden.
    Reid, Michael S.
    KTH Royal institute of Technology, Sweden.
    Rautkoski, Hille
    VTT Technical Research Centre of Finland, Finland.
    Holopainen-Mantila, Ulla
    VTT Technical Research Centre of Finland, Finland.
    Oinonen, Petri
    Ecohelix, Sweden.
    Henriksson, Gunnar
    KTH Royal institute of Technology, Sweden.
    Layer-by-layer assembly of sustainable lignin-based coatings for food packaging applications2023Ingår i: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 182, artikel-id 107676Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging. 

  • 3.
    Berglin, Mattias
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning. University of Gothenburg, Sweden.
    Cavanagh, Jorunn Pauline
    Amicoat A/S, Norway; UiT The Arctic University of Norway, Norway.
    Caous, Josefin Seth
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Thakkar, Balmukund Sureshkumar
    Amicoat A/S, Norway.
    Vasquez, Jeddah Marie
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Stensen, Wenche
    UiT The Arctic University of Norway, Norway.
    Lyvén, Benny
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Svendsen, John-Sigurd
    Amicoat A/S, Norway; UiT The Arctic University of Norway, Norway.
    Svenson, Johan
    RISE Research Institutes of Sweden, Material och produktion.
    Flexible and Biocompatible Antifouling Polyurethane Surfaces Incorporating Tethered Antimicrobial Peptides through Click Reactions2023Ingår i: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Efficient, simple antibacterial materials to combat implant-associated infections are much in demand. Herein, the development of polyurethanes, both cross-linked thermoset and flexible and versatile thermoplastic, suitable for “click on demand” attachment of antibacterial compounds enabled via incorporation of an alkyne-containing diol monomer in the polymer backbone, is described. By employing different polyolic polytetrahydrofurans, isocyanates, and chain extenders, a robust and flexible material comparable to commercial thermoplastic polyurethane is prepared. A series of short synthetic antimicrobial peptides are designed, synthesized, and covalently attached in a single coupling step to generate a homogenous coating. The lead material is shown to be biocompatible and does not display any toxicity against either mouse fibroblasts or reconstructed human epidermis according to ISO and OECD guidelines. The repelling performance of the peptide-coated materials is illustrated against colonization and biofilm formation by Staphylococcus aureus and Staphylococcus epidermidis on coated plastic films and finally, on coated commercial central venous catheters employing LIVE/DEAD staining, confocal laser scanning microscopy, and bacterial counts. This study presents the successful development of a versatile and scalable polyurethane with the potential for use in the medical field to reduce the impact of bacterial biofilms. 

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  • 4.
    Breijaert, T. C.
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Daniel, G.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Hedlund, D.
    Uppsala University, Sweden.
    Svedlindh, P.
    Uppsala University, Sweden.
    Kessler, V. G.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Granberg, Hjalmar
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Håkansson, Karl
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Seisenbaeva, G. A.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Self-assembly of ferria – nanocellulose composite fibres2022Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 291, artikel-id 119560Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An environmentally benign synthesis of a magnetically responsive carboxymethylated cellulose nanofibril-based material is reported. Applied experimental conditions lead to the in-situ formation of magnetite nanoparticles with primary particle sizes of 2.0–4.0 nm or secondary particles of 3.6–16.4 nm depending on whether nucleation occurred between individual carboxymethylated cellulose nanofibrils, or on exposed fibril surfaces. The increase in magnetite particle size on the cellulose fibril surfaces was attributed to Ostwald ripening, while the small particles formed within the carboxymethyl cellulose aggregates were presumably due to steric interactions. The magnetite nanoparticles were capable of coordinating to carboxymethylated cellulose nanofibrils to form large “fibre-like” assemblies. The confinement of small particles within aggregates of reductive cellulose molecules was most likely responsible for excellent conservation of magnetic characteristics on storage of this material. The possibility for using the material in drug delivery applications with release rate controlled by daylight illumination is presented. © 2022 The Author(s)

  • 5.
    Chen, Fei
    et al.
    KTH Royal Institute of Technology, Sweden.
    Nilsson, Fritjof
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE., Innventia.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Chitosan extrusion at high solids content: An orthogonal experimental design study2014Ingår i: Polymers from Renewable Resources, ISSN 2045-1377, Vol. 5, nr 1, s. 1-12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For economic reasons and to save time there is a need to shorten the drying operation associated with the production of chitosan materials. Hence it is of interest to extrude chitosan at as high a solids content as possible. This is, to our knowledge, the first systematic study of the extrusion of chitosan at high solids content (60 wt%). An orthogonal experimental design was used to evaluate the effect of processing conditions and material factors on the extrudability of chitosan. This, together with the examination of the evenness and surface finish of the extrudate, made it possible to determine the best conditions for obtaining a readily extrudable high quality material. It was observed that a 1/1 ratio of chitosans with molar masses of 12 and 133 kDa, a process liquid containing 30 wt% acetic acid and 70 wt% water, and extrusion at 50 rpm and 50°C were the optimal material and processing conditions. Materials processed under these conditions were evaluated mechanically at different times after extrusion (stored at 50% RH) in order to see when the properties stabilized. Most mass loss occurred within the first three days after extrusion and this governed the mechanical properties (stiffness and extensibility), which also exhibited the largest changes within these three days (an increase in modulus from 18 to 830 MPa and a decrease in elongation at break from 17 to 3%).

  • 6.
    Chinga-Carrasco, Gary
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Johansson, Jenny
    RISE Research Institutes of Sweden, Material och produktion.
    Heggset, Ellinor B
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Leirset, Ingebjørg
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Björn, Camilla
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Agrenius, Karin
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Stevanic Srndovic, Jasna
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Håkansson, Joakim
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil. Gothenburg University, Sweden.
    Characterization and Antibacterial Properties of Autoclaved Carboxylated Wood Nanocellulose.2021Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 22, nr 7, s. 2779-2789Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanofibrils (CNFs) were obtained by applying a chemical pretreatment consisting of autoclaving the pulp fibers in sodium hydroxide, combined with 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation. Three levels of sodium hypochlorite were applied (2.5, 3.8, and 6.0 mmol/g) to obtain CNF qualities (CNF_2.5, CNF_3.8, and CNF_6.0) with varying content of carboxyl groups, that is, 1036, 1285, and 1593 μmol/g cellulose. The cytotoxicity and skin irritation potential (indirect tests) of the CNFs were determined according to standardized in vitro testing for medical devices. We here demonstrate that autoclaving (121 °C, 20 min), which was used to sterilize the gels, caused a modification of the CNF characteristics. This was confirmed by a reduction in the viscosity of the gels, a morphological change of the nanofibrils, by an increase of the ultraviolet-visible absorbance maxima at 250 nm, reduction of the absolute zeta potential, and by an increase in aldehyde content and reducing sugars after autoclaving. Fourier-transform infrared spectroscopy and wide-angle X-ray scattering complemented an extensive characterization of the CNF gels, before and after autoclaving. The antibacterial properties of autoclaved carboxylated CNFs were demonstrated in vitro (bacterial survival and swimming assays) on Pseudomonas aeruginosa and Staphylococcus aureus. Importantly, a mouse in vivo surgical-site infection model on S. aureus revealed that CNF_3.8 showed pronounced antibacterial effect and performed as good as the antiseptic Prontosan wound gel.

  • 7.
    Flodberg, Göran
    et al.
    RISE., Innventia.
    Helland, Irene
    Norner Innovation AS, Norway.
    Thomson, Lars
    RISE., Innventia.
    Bodil Fredriksen, Siw
    Norner Innovation AS, Norway.
    Barrier properties of polypropylene carbonate and poly(lactic acid) cast films2015Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 63, s. 217-226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A comparative study of the barrier properties of cast film of polypropylene carbonate (PPC) and cast film of poly(lactic acid) (PLA) has been made in this paper. Dynamic transmission measurements were conducted to obtain the barrier properties for oxygen transmission and for water vapour transmission. A special algorithm fminsearch in Matlab was used to adapt an exponential expression to the measured values. In this way the time needed to reach a 95% level of steady state was made possible to identify. The oxygen permeability was lower for PPC compared to PLA and this could be explained by a much higher positive enthalpy of solution for oxygen in PPC. The enthalpy of diffusion was close to similar for both PPC and PLA and was higher than for enthalpy of solution. The enthalpy of water vapour permeability was higher for PPC compared to PLA and this resulted in substantially higher water vapour permeability for PLA. The uptake of water vapour was also higher for PLA compared to PPC as shown by dynamic vapour sorption measurements. Differential scanning calorimetry confirmed that PPC is an amorphous polymer and that the PLA used in this study had a minimum of crystallinity which made it comparable to PPC.

  • 8.
    Guo, Zengwei
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Adolfsson, Erik
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Tam, Pui
    Chalmers University of Technology, Sweden.
    Nanostructured micro particles as a low-cost and sustainable catalyst in the recycling of PET fiber waste by the glycolysis method2021Ingår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 126, s. 559-566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magnetic Mg-Al-O@Fe3O4 micro particles were synthesized by coating nanosized Mg-Al double oxides onto Fe3O4 micro particles. The formed hierarchical structure gave Mg-Al-O@Fe3O4 micro particles a high active surface area, which enabled these micro particles to work efficiently as a catalyst in the glycolysis of poly(ethylene terephthalate) (PET). The bis(hydroxyethyl) terephthalate (BHET) yield reached above 80 mol% in the presence of 0.5 wt% of Mg-Al-O@Fe3O4 micro catalyst in the reaction system within 90 min at 240 °C. After the reaction, Mg-Al-O@Fe3O4 micro catalyst was easily retrieved by a magnetic decantation and can be repetitively used for two times with a high catalytic efficiency. After that, the deactivated Mg-Al-O@Fe3O4 micro catalyst can be regenerated by heat treatment. The regenerated Mg-Al-O@Fe3O4 micro catalyst displays a comparable catalytic performance as that of the virgin catalyst. In addition, the Mg-Al double oxides and Fe3O4 micro particles are low-cost and environmentally benign. Therefore, the Mg-Al-O@Fe3O4 micro catalyst may contribute to an economically and environmentally improved large-scale circular recycling of PET fiber waste. © 2021 The Author(s)

  • 9.
    Hui, Isabel
    et al.
    Swiss Federal Institute of Technology Zurich, Switzerland.
    Pasquier, Eva
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Solberg, Amalie
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Agrenius, Karin
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Håkansson, Joakim
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning. University of Gothenburg, Sweden.
    Chinga Carrasco, Gary
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Biocomposites containing poly(lactic acid) and chitosan for 3D printing: Assessment of mechanical, antibacterial and in vitro biodegradability properties2023Ingår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 147, artikel-id 106136Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New bone repair materials are needed for treatment of trauma- and disease-related skeletal defects as they still represent a major challenge in clinical practice. Additionally, new strategies are required to combat orthopedic device-related infections (ODRI), given the rising incidence of total joint replacement and fracture fixation surgeries in increasingly elderly populations. Recently, the convergence of additive manufacturing (AM) and bone tissue engineering (BTE) has facilitated the development of bone healthcare to achieve personalized three-dimensional (3D) scaffolds. This study focused on the development of a 3D printable bone repair material, based on the biopolymers poly(lactic acid) (PLA) and chitosan. Two different types of PLA and chitosan differing in their molecular weight (MW) were explored. The novel feature of this research was the successful 3D printing using biocomposite filaments composed of PLA and 10 wt% chitosan, with clear chitosan entrapment within the PLA matrix confirmed by Scanning Electron Microscopy (SEM) images. Tensile testing of injection molded samples indicated an increase in stiffness, compared to pure PLA scaffolds, suggesting potential for improved load-bearing characteristics in bone scaffolds. However, the potential benefit of chitosan on the biocomposite stiffness could not be reproduced in compression testing of 3D printed cylinders. The antibacterial assays confirmed antibacterial activity of chitosan when dissolved in acetic acid. The study also verified the biodegradability of the scaffolds, with a process producing an acidic environment that could potentially be neutralized by chitosan. In conclusion, the study indicated the feasibility of the proposed PLA/chitosan biocomposite for 3D printing, demonstrating adequate mechanical strength, antibacterial properties and biodegradability, which could serve as a new material for bone repair.

  • 10.
    Javed, Asif
    et al.
    Karlstad University, Sweden.
    Rättö, Peter
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi. Karlstad University, Sweden.
    Järnström, Lars
    Karlstad University, Sweden.
    Ullsten, Henrik
    Calamo AB, Sweden.
    Lignin-containing coatings for packaging materials—pilot trials2021Ingår i: Polymers, E-ISSN 2073-4360, Vol. 13, nr 10, artikel-id 1595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples. © 2021 by the authors

  • 11.
    Javed, Asif
    et al.
    Karlstad University, Sweden.
    Ullsten, Henrik
    Karlstad University, Sweden.
    Ernstsson, Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Järnström, Lars
    Karlstad University, Sweden.
    Study of starch and starch-PVOH blends and effects of plasticizers on mechanical and barrier properties of coated paperboard2016Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, nr 3, s. 499-510Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical properties of self-supporting films based on starch-plasticizer and starch-PVOH-plasticizer and the barrier properties of paperboard coated with solutions of these polymers have been studied. The plasticizers used were glycerol, polyethylene glycol and citric acid. It was shown that the addition of a plasticizer and PVOH to starch substantially increases the flexibility of starch films. It was seen that curing the self-supporting films led to a decrease in flexibility. After heat-treatment, a substantial increase in storage modulus was observed only in the starch-PVOH-citric-acid blend films. Tensile tests on the films indicate that citric acid did not cause any noticeable phase separation. Citric acid acted as a compatibilizer for starch-PVOH blends even though a similar enrichment of PVOH at the air-solid interface was observed with both citric acid and polyethylene glycol as plasticizer. The properties of barrier coatings greatly reflected the compatibility of starch-PVOH blends containing citric acid. The only plasticizer that resulted in a lower water vapour transmission rate through the starch and starch-PVOH coatings was citric acid, which suggests that cross-linking took place. With four layers, coatings based of starch-PVOH possessed the same oxygen- transmission rate with citric acid as without citric acid.

  • 12.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi. KTH Royal Institute of Technology, Sweden.
    Hansson, Per
    Uppsala University, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Thermodynamics of the Water-Retaining Properties of Cellulose-Based Networks2019Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, nr 4, s. 1603-1612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Noncrystalline cellulose-based gel beads were used as a model material to investigate the effect of osmotic stress on a cellulosic network. The gel beads were exposed to osmotic stress by immersion in solutions with different concentrations of high molecular mass dextran and the equilibrium dimensional change of the gel beads was studied using optical microscopy. The volume fraction of cellulose was calculated from the volume of the gel beads in dextran solutions and their dry content and the relation between the cellulose volume fraction and the total osmotic pressure was thus obtained. The results show that the contribution to the osmotic pressure from counterions increases the water-retaining capacity of the beads at high osmotic pressures but also that the main factor controlling the gel bead collapse at high osmotic strains is the resistance to the deformation of the polymer chain network within the beads. Furthermore, the osmotic pressure associated with the deformation of the polymer network, which counteracts the deswelling of the beads, could be fitted to the Wall model indicating that the response of the cellulose polymer networks was independent of the charge of the cellulose. The best fit to the Wall model was obtained when the Flory-Huggins interaction parameter (χ) of the cellulose-water system was set to 0.55-0.60, in agreement with the well-established insolubility of high molecular mass β-(1,4)-d-glucan polymers in water.

  • 13.
    Kuktaite, Ramune
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Plivelic, Tomás S.
    Lund University, Sweden.
    Ture, Hasan
    KTH Royal Institute of Technology, Sweden.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE., Innventia.
    Marttila, Salla
    SLU Swedish University of Agricultural Sciences, Sweden.
    Johansson, Eva
    SLU Swedish University of Agricultural Science, Sweden.
    Changes in the hierarchical protein polymer structure: Urea and temperature effects on wheat gluten films2012Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 2, nr 31, s. 11908-11914Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding bio-based protein polymer structures is important when designing new materials with desirable properties. Here the effect of urea on the wheat gluten (WG) protein structure in WG-urea films was investigated. Small-angle X-ray scattering indicated the formation of a hexagonal close-packed (HCP) hierarchical structure in the WG-urea materials. The HCP structure was influenced significantly by the urea concentration and processing conditions. The interdomain distance d I between the HCP scattering objects increased with increasing content of urea and the objects seemed to be oriented in the extrusion direction. Additionally, the effect of temperature on the HCP structure was studied and it was shown that at ≥55°C the HCP structure disappeared. Transmission electron microscopy revealed a rather denatured pattern of both HMW-glutenins and gliadins in the WG-urea films. The molecular packing of the WG protein polymer can be highly affected by an additive and the processing method used.

  • 14.
    López, Alvaro
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Marteleur, Klas
    Cytiva, Sweden.
    Finne-Wistrand, Anna
    KTH Royal Institute of Technology, Sweden.
    Impact of storage at different thermal conditions on surface characteristics of 3D printed polycaprolactone and poly(ε-caprolactone-co-p-dioxanone) scaffolds2023Ingår i: Bioprinting, ISSN 2405-8866, Vol. 33, artikel-id e00293Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fused filament fabrication (FFF) is a commonly used method for producing three-dimensional scaffolds using synthetic, degradable polymers. However, there are several variables that must be considered when fabricating devices for clinical use, one of which is storage conditions after printing. While the academic community has examined the impact of FFF on mechanical and thermal properties, there has been less focus on how storage conditions would affect the surface texture of scaffolds. Our hypothesis was that the surface, thermal and physical properties of FFF scaffolds are significantly influenced by the storage conditions. We evaluated the surfaces of FFF poly (ε-caprolactone) (PCL) and poly (ε-caprolactone-co-p-dioxanone) (PCLDX) strands that were stored at 4 °C, 20 °C, and 37 °C for 28 days. We monitored surface texture, physical and thermal changes to understand the effect of storage on the strands. The implementation of scale-sensitive fractal analysis and feature parameters revealed that storage conditions at 37 °C increased the number of hills and dales, as well as the density of peaks and pits compared to 20 °C and 4 °C, for both materials. The feature roughness parameters for PCL had up to 90% higher values than those of PCLDX, which correlated with the physical and thermal properties of the materials. These differences may impact further surface-cell interaction, highlighting the need for further evaluation for faster clinical translation. Our findings emphasize the importance of considering storage conditions in the design and manufacture of FFF scaffolds and suggest that the use of feature roughness parameters could facilitate the optimization and tailoring the surface properties for specific applications. © 2023 The Authors

  • 15.
    Naderi, Ali
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi. RISE., Innventia. BillerudKorsnäs, Sweden.
    Koschella, Andreas
    Friedrich Schiller University of Jena, Germany.
    Heinze, Thomas
    Friedrich Schiller University of Jena, Germany.
    Shih, Kuo-Chih
    University of Connecticut, USA; National Taiwan University, Taiwan.
    Nieh, Mu-Ping
    University of Connecticut, USA.
    Pfeifer, Annett
    Friedrich Schiller University of Jena, Germany.
    Chang, Chung-Chueh
    Stony Brook University, USA.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Sulfoethylated nanofibrillated cellulose: Production and properties2017Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 169, s. 515-523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sulfoethylated nanofibrillated cellulose (NFCSulf) was produced by an industrially relevant process. The properties of the NFCSulf were compared with those of carboxymethylated nanofibrillated cellulose (NFCCarb), which has been identified as an attractive NFC for several industrial applications. The investigations revealed that NFCSulf is characterized by a higher degree of fibrillation and has superior redispersion properties. Furthermore, NFCSulf displays higher stability in varying pH values as compared to NFCCarb. Hence, NFCSulf may be a more attractive alternative than NFCCarb in applications such as rheological modifiers or adsorbing components in personal care products, in which the performance of NFC must remain unaffected in varying ambient conditions. The superior properties of NFCSulf compared to NFCCarb were proposed to be due to the combination of the unique chemical characteristics of the sulfoethylated reagent, and the larger size of the sulfonate group compared to the carboxymethyl group.

  • 16.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Pettersson, Torbjörn
    KTH Royal Institute of Technology, Sweden.
    The state of carboxymethylated nanofibrils after homogenization-aided dilution from concentrated suspensions: A rheological perspective2014Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 4, s. 2357-2368Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rheological properties of a carboxymethylated (D.S. ≈ 0.1) nanofibrillated cellulose (NFC) were investigated at different solid contents. The critical overlap concentration was determined to be in the range between 0.04 and 0.07 % (w/w) using shear stress versus shear rate measurements. From the critical overlap concentration using the simple Mason excluded volume formalism, the apparent aspect ratio was estimated to be 75 [at a critical overlap concentration of 0.04 % (w/w)]. The aspect ratio of the NFC system was also estimated by using the Einstein-Simha equation together with the intrinsic viscosity value of the system (corrected for the electroviscous effects). The obtained value was found to be around 80, which is in good agreement with the value obtained from the excluded volume calculation. Further, by combining oscillatory measurements and the equation of Shankar et al. the apparent fibril length was determined to be 4 μm. As the production of NFC through homogenization occurs at concentrations far above the critical overlap concentration an NFC-gel is constituted by a severely entangled structure. The disentanglement of the fibrils is therefore difficult and the employed dilution method was found not to lead to fully liberated nanofibrils, which was also indicated by atomic force microscopy-imaging.

  • 17.
    Nechyporchuk, Oleksandr
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Regenerated Casein-Nanocellulose Composite Fibers via Wet Spinning2019Ingår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 7, nr 1, s. 1419-1426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Development of sustainable biobased fibers is required to displace their fossil-based counterparts, e.g., in textile, nonwoven, or composite applications. Regenerated protein fibers have a potential in this regard if their mechanical properties are improved. Herein, we study for the first time the use of nanocellulose as reinforcement in regenerated protein fibers produced using wet spinning. The influence of cellulose nanocrystals (CNC) incorporated into regenerated casein fibers is examined in terms of mechanical and morphological properties. The influence of different conditions for fiber chemical cross-linking is also investigated. Incorporation of CNC (up to 37.5 wt %) into spin dopes results in a continuous increase of fiber Young's modulus (up to twofold) in the dry state. Both maximum and breaking tenacity of dry fibers are enhanced by CNC, with a maximum at 7.0-10.5 wt % of CNC. When testing after being wetted, both breaking tenacity and Young's modulus of the composite fibers decrease, likely due to weakening of hydrogen bonds between CNC in the presence of water. We also demonstrate that the presence of salt during chemical cross-linking is crucial to produce intact and separated fibers in the yarn.

  • 18.
    Newson, William R.
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Rasheed, Faiza
    SLU Swedish University of Agricultural Sciences, Sweden.
    Kuktaite, Ramune
    SLU Swedish University of Agricultural Sciences, Sweden.
    Hedenqvist, Mikael S.
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE., Innventia.
    Plivelic, Tomás S.
    Lund University, Sweden.
    Johansson, Eva
    SLU Swedish University of Agricultural Sciences, Sweden.
    Commercial potato protein concentrate as a novel source for thermoformed bio-based plastic films with unusual polymerisation and tensile properties2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 41, s. 32217-32226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Commercial potato protein concentrate (PPC) was investigated as a source of thermoformed bio-based plastic film. Pressing temperatures of 100 to 190°C with 15 to 25% glycerol were used to form PPC films. The shape of the tensile stress-strain curve in thermoformed PPC was controlled by glycerol level and was independent of processing temperature. Tensile testing revealed that elongation at break increased with processing temperature while Young's modulus was unaffected by processing temperature, both in contrast to previous results in protein based systems. Also in contrast to previous studies, Young's modulus was found to be only sensitive to glycerol level. Maximum tensile stress increased with increasing processing temperature for PPC films. Maximum stress and strain at break correlated with the extractable high molecular weight protein content of the processed films measured with size exclusion chromatography. Infrared absorption indicated that the content of β-sheet structure increased from the commercial protein concentrate to that pressed at 100°C, but did not further develop with increasing press temperature. Changes in structural arrangements were observed by small angle X-ray scattering indicating the development of different correlation distances with processing temperature but with no clear long range order at the supramolecular level. The novel Young's modulus behaviour appears to be due to constant secondary structure or the effect of aggregated protein structure formed during protein production. Unique strain at break behaviour with processing temperature was demonstrated, likely due to new connections formed between those aggregates.

  • 19.
    Nilsson, Helena
    et al.
    RISE., STFI-Packforsk.
    Olsson, Ann
    RISE., STFI-Packforsk.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Iversen, Tommy
    RISE., STFI-Packforsk.
    Bark suberin as a renewable source of long-chain ω-hydroxyalkanoic acids2008Ingår i: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 272, nr 1, s. 104-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polycondensations of cis-9,10-epoxy-18-hydroxyoctadecanoic acid, isolated from birch outer bark, were performed at 75°C in toluene as solvent and at 85°C In bulk using immobilized Candida antarctica lipase B as catalyst. The polycondensation performed in toluene in presence of molecular sieves gave a polyester with DP 50 after 24 h. The same DP was obtained at much shorter reaction time (3 h) by bulk polymerization in an open vial without any drying agent present.

  • 20.
    Ovaska, Sami-Seppo
    et al.
    Lappeenranta University of Technology, Finland.
    Hiltunen, Salla
    Lappeenranta University of Technology, Finland.
    Ernstsson, Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Schuster, Erich
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Altskär, Annika
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Backfolk, Kaj
    Lappeenranta University of Technology, Finland.
    Characterization of rapeseed oil/coconut oil mixtures and their penetration into hydroxypropylated-starch-based barrier coatings containing an oleophilic mineral2016Ingår i: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 101, s. 569-576Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A study was conducted that demonstrated that the blending of edible oils leads to changes in surface tension, thermal properties, viscosity, and oil penetration times through a barrier-coated paperboard. The results emphasize the significance of testing the oil and grease resistance (OGR) oil blends in order-to verify the suitability of the packaging material for real-life end-use applications. The results of the OGR determinations suggest that hydroxypropylated-starch-based composite coatings containing an oleophilic high aspect ratio mineral can be tailored for food shaving different fatty acid compositions by varying the pigmentation level. Compared to standard OGR tests, confocal laser scanning microscopy (CLSM)-based techniques make it possible to evaluate the oil penetration time and its diffusion behavior very accurately, both inside the coating layer and in the bulk matrix. It was found that, at room temperature, coconut oil tends to crystallize inside the substrate, inducing swelling of the coating layer, which probably has an influence on the physicomechanical properties of the packaging material.

  • 21.
    Petersen, Henrik
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Enebro, Jonas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Development of nanocomposites based on organically modified montmorillonite and plasticized PVC with improved barrier properties2016Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, nr 3, artikel-id 42876Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Montmorillonite (MMT) was organically modified with tributyl citrate (TBC). Organoclays (OMMTs) were processed with diisononyl phthalate (DINP)-plasticized polyvinyl chloride (PVC) to form polymer nanocomposites. The produced composite materials showed a contradictory change in properties to that expected of a layered silicate nanocomposite, with a decreased E-modulus and increased gas permeability compared with a material without OMMT. It was experimentally shown that the TBC modifier was extracted from the OMMT and was dispersed in the PVC/DINP matrix, whereupon the OMMT collapsed and formed micrometer-sized agglomerates. Further investigation revealed that TBC has a significant effect on the gas permeability and the E-modulus, even at low additions to a DINP-plasticized PVC. A PVC nanocomposite with the TBC acting as both the OM for MMT and as the primary plasticizer was produced. This material showed a significantly increased E-modulus as well as a decrease in gas permeability, confirming that it is possible to develop a nanocomposite based on plasticized PVC, if both the organo-modification of the MMT and the formulation of the matrix are carefully selected.

  • 22.
    Sjöstedt, Anna
    et al.
    KTH Royal Institute of Technology, Sweden.
    Wohlert, Jakob
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Structural changes during swelling of highly charged cellulose fibres2015Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 5, s. 2943-2953Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Structural changes of fibrils and fibril aggregates in the fibre wall were studied after oxidation of the cellulose by 2,2,6,6-tetramethyl-1-piperidinyloxy to high charge densities (highest charge density: 1300 μeq/g). The increase in pore volume was measured by mini-WRV at two different pH levels, and the supramolecular structure in the fibre wall in terms of aggregate size, specific surface area and average pore size was measured by solid state NMR, DVS desorption and BET N2 gas adsorption. A structural change in the arrangement of the fibrils inside the fibril aggregates was observed although the oxidation did not lead to a complete liberation of individual fibrils, i.e. they still exist as an aggregated structure after oxidation. Theoretical estimates suggest that the electrostatic repulsion energy connected with the increase in surface charge of the fibrils can be sufficient to gradually separate the fibrils enough to expose all fibril surfaces to oxidation chemicals.

  • 23.
    Stading, Mats
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience. Chalmers University of Technology, Sweden.
    Levenstam Bragd, Emma
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience.
    Johansson, Daniel
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience.
    Renewable Gas Barriers for Paper Coating2013Ingår i: Annual Transactions of the Nordic Rheology Society, s. 327-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We annually produce 400 million tonnes of paper and board globally and a large part is produced in the Nordic countries. Almost all paper is coated and there is specifically a need for renewable gas barriers for packaging use. Dispersion coating is an efficient coating process, but also one with high demands on the rheological properties of the coating formulation. Dispersion coating based on cereal proteins was developed and the coatings were both strong and gas tight.

  • 24.
    Svärd, Antonia
    et al.
    KTH Royal Institute of Technology, Sweden.
    Brännvall, Elisabet
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, Bioraffinaderi och energi.
    Edlund, Ulrica
    KTH Royal Institute of Technology, Sweden.
    Modified and thermoplastic rapeseed straw xylan: A renewable additive in PCL biocomposites2018Ingår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 119, s. 73-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Xylan extracted from rapeseed straw was chemically modified to gain hydrophobic and thermoplastic properties via macroinitiator formation followed by a free radical grafting-from polymerization with octadecyl acrylate. Biocomposites were then prepared by incorporation of 5 or 20% (w/w) rapeseed straw xylan into a poly(ε-caprolactone) (PCL) matrix by melt extrusion. The grafted xylan was homogeneously distributed within the biocomposite and reinforced the PCL matrix while at the same time preserving the ability to elongate to tensile strains >500%. Analogous biocomposites made from unmodified xylan in a PCL matrix resulted in heterogeneous mixtures and brittle tensile properties.

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  • 25.
    Wang, Miao
    et al.
    RISE., Innventia.
    Sjöholm, Elisabeth
    RISE., Innventia.
    Li, Jiebing
    RISE., Innventia.
    On lignin reactivity quantification for lignin substitution of phenol in preparation of phenol-formaldehyde polymer2014Konferensbidrag (Refereegranskat)
  • 26.
    Wärnheim, Alexander
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Korrosion.
    Edvinsson, Camilla
    RISE Research Institutes of Sweden, Material och produktion, Korrosion.
    Sundell, Per-Erik
    SSAB Europe, Sweden.
    Heydari, Golrokh
    SSAB Europe, Sweden.
    Deltin, Tomas
    Nordic United Coatings, Sweden.
    Persson, Dan
    RISE Research Institutes of Sweden, Material och produktion, Korrosion.
    Depth-Resolved FTIR-ATR Imaging Studies of Coating Degradation during Accelerated and Natural Weathering─Influence of Biobased Reactive Diluents in Polyester Melamine Coil Coating2022Ingår i: ACS Omega, E-ISSN 2470-1343, Vol. 7, nr 27, s. 23842-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Improved methods to assess the degradation of coil coatings to approximate lifetime have been an area of academic and industrial interest for decades. This work aims to elucidate the differences in the degradation behavior of two coil coating systems: one standard commercial formulation and one formulation with a significant addition of biorenewable reactive diluents. Depth-resolved degradation behavior of samples exposed to accelerated and natural field weathering is assessed. Focal plane array attenuated total reflection-Fourier transform infrared spectroscopy was used to acquire high-resolution chemical data from a sloping cross section. The results agreed with conventional photoacoustic spectroscopy. Degradation profiles for the two coatings were significantly different, with the biobased samples showing a more durable behavior. This study provides a method for detailed assessment of coating degradation, giving a good estimation of its durability. This is both a way to compare the performance of coating systems and to improve the understanding of the impact of exposure conditions, paving the way for the development of more sustainable coil coatings.

  • 27.
    Ye, Xinchen
    et al.
    KTH Royal Institute of Technology, Sweden.
    Junel, Kristina
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, Papperstillverkning och förpackningar. RISE Research Institutes of Sweden, Bioekonomi och hälsa, Massa, papper och förpackningar.
    Gällstedt, Mikael
    SIG Combibloc, Sweden.
    Langton, Maud
    SLU Swedish University of Agricultural Sciences, Sweden.
    Wei, Xin-Feng
    KTH Royal Institute of Sweden, Sweden.
    Lendel, Christofer
    KTH Royal Institute of Sweden, Sweden.
    Hedenqvist, Mikael S.
    KTH Royal Institute of Sweden, Sweden.
    Protein/Protein Nanocomposite Based on Whey Protein Nanofibrils in a Whey Protein Matrix2018Ingår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 6, nr 4, s. 5462-5469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article describes nanocomposite films with separately grown protein nanofibrils (PNFs) in a nonfibrillar protein matrix from the same protein starting material (whey). Tensile tests on the glycerol-plasticized films indicate an increased elastic modulus and a decreased extensibility with increasing content of PNFs, although the films are still ductile at the maximum PNF content (15 wt %). Infrared spectroscopy confirms that the strongly hydrogen-bonded β-sheets in the PNFs are retained in the composites. The films appear with a PNF-induced undulated upper surface. It is shown that micrometer-scale spatial variations in the glycerol distribution are not the cause of these undulations. Instead, the undulations seem to be a feature of the PNF material itself. It was also shown that, apart from plasticizing the protein film, the presence of glycerol seemed to favor to some extent exfoliation of stacked β-sheets in the proteins, as revealed by X-ray diffraction.

  • 28.
    Zhao, Wei
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign. Uppsala University, Sweden.
    Sugunan, Abhilash
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Gillgren, Thomas
    BillerudKorsnäs AB, Sweden.
    Larsson, Johan A
    BillerudKorsnäs AB,Sweden.
    Zhang, Zhi-Bin
    Uppsala University, Sweden.
    Zhang, Shi-Li
    Uppsala University, Sweden.
    Sommertune, Jens
    RISE Research Institutes of Sweden.
    Dobryden, Illia
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Ahniyaz, Anwar
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Surfactant-free starch-graphene composite films as simultaneous oxygen and water vapour barriers2022Ingår i: npj 2D Materials and Applications, ISSN 2397-7132, Vol. 6, nr 1, artikel-id 20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A single coating formulation for multifunctional composites, such as a gas barrier against both oxygen and water vapour, is the holy grail for the packaging industry. Since the last decade, graphene has been touted as the ideal barrier material in composites due to its morphology and impermeability to all gases. However, this prospect is limited by either poor dispersion of graphene or excess surfactants to aid the dispersion, both leading to shortcuts that allow gas permeation through the composite. Here, we demonstrate a combined gas barrier with starch-graphene composite films made from a single formulation of surfactant-free starch nanoparticle-stabilized graphene dispersion (2.97 mg mL−1). Hence, the incorporated graphene reduces the permeability of both the oxygen and the water vapour by over 70% under all the relative humidity conditions tested. Moreover, these films are foldable and electrically conductive (9.5 S m−1). Our surfactant-free approach of incorporating graphene into an industrially important biopolymer is highly relevant to the packaging industry, thus offering cost-effective and water-based solution depositions of multifunctional composite films for wide-ranging applications, such as gas barriers in food packaging. © 2022, The Author(s).

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