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  • 1.
    Abitbol, Tiffany
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Mijlkovic, Ana
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Malafronte, Loredana
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Stevanic Srndovic, Jasna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Larsson, Per Tomas
    RISE Research Institutes of Sweden.
    Lopez-Sanchez, Patricia
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Cellulose nanocrystal/low methoxyl pectin gels produced by internal ionotropic gelation.2021In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 260, article id 117345Article in journal (Refereed)
    Abstract [en]

    The biotechnological applications of cellulose nanocrystals (CNCs) continue to grow due to their sustainable nature, impressive mechanical, rheological, and emulsifying properties, upscaled production capacity, and compatibility with other materials, such as protein and polysaccharides. In this study, hydrogels from CNCs and pectin, a plant cell wall polysaccharide broadly used in food and pharma, were produced by calcium ion-mediated internal ionotropic gelation (IG). In the absence of pectin, a minimum of 4 wt% CNC was needed to produce self-supporting gels by internal IG, whereas the addition of pectin at 0.5 wt% enabled hydrogel formation at CNC contents as low as 0.5 wt%. Experimental data indicate that CNCs and pectin interact to give robust and self-supporting hydrogels at solid contents below 2.5 %. Potential applications of these gels could be as carriers for controlled release, scaffolds for cell growth, or wherever else distinct and porous network morphologies are required.

  • 2.
    Andersson, Jan-Erik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Nordman, Roger
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Vikberg, Tommy
    Luleå Technical University, Sweden.
    Energy mapping in the sawmill industry with focus on drying kilns2013Conference paper (Other academic)
    Abstract [en]

    The forest industry stands for approximately 11 % of Sweden’s total export. However, the forest industry is energy intensive. In 2008, sawmill industry alone consumed almost 8,7 TWh of energy, corresponding to 5 % of the Swedish industries total energy consumption. Out of their total consumption, 2200 GWh was electric power, 194 GWh heating oil , 4229 GWh bio-fuel, 574 GWh district heating, and other fuels such as diesel 1503 GWh [1].The project ”EESI- Energy Efficiency in the Sawmill Industry” was started in the spring of 2010 with the aim of demonstrating the possibilities to reduce the energy consumption in the sawmill industry with 20 % by 2020. 16 sawmill corporations and 14 equipment suppliers has joined the project which is carried out in two phases of which the first phase was carried out during 2010 and 2011. EESI has now reached half time and the first energy-saving implementations have been completed at the participating sawmills.This paper presents the energy-mapping, measurements and modelling performed by the participating sawmills during the first phase of the project [2, 3]. The average energy consumption per sawn cubic metre of boards varied between approximately 300 to 500 kWh/m3. Out of this, the electricity consumption was on average 85 kWh/m3, bio-fuel 290 kWh/m3 and diesel 1.8 l/m3.However, the main concern from sawmills regarding energy consumption was the wood drying process. The striking results from the preliminary measurements were the large variation in energy consumption even with similar drying kilns. This was especially apparent for the heat consumption in kiln dryers which could vary as much as 50 % for the same dimension of spruce planks.The results from the first phase of the project resulted in a large number of actions in order to reduce the energy consumption which are now being implemented or have already been completed. Examples of those actions are: simplified management system adapted to sawmills, weighing of packages for more accurate wood drying, reduced speed or intermittent operation of the air circulating fans in batch kilns and moisture content measurements of bio-fuel.References[1] Statistiska centralbyrån (SCB), 2013, Industrins årliga energianvändning 2011, Slutliga uppgifter, EN23SM1301, ISSN 1654-367X. (In Swedish). [2] Andersson, J-E., Lycken, A., Nordman, R., Olsson, M., Räftegård, O., and Wamming, T. State of the art – Energianvändning i den svenska sågverksindustrin. SP Rapport 2011:42, ISBN 978-91-86622-72-5. (In Swedish).[3] Andersson, J-E., Räftegård, O., Lycken, A., Olsson, M., Wamming, T., and Nordman, R. Sammanställning av energimätningar från EESI fas 1. SP Rapport 2011:41, ISBN 978-91-86622-71-8. (In Swedish).

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  • 3.
    Arya, Mina
    et al.
    University of Borås, Sweden.
    Malmek, Else-Marie
    Juteborg AB, Sweden.
    Ecoist, Thomas Koch
    Ecoist AB, Sweden.
    Pettersson, Jocke
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Skrifvars, Mikael
    University of Borås, Sweden.
    Khalili, Pooria
    University of Borås, Sweden.
    Enhancing Sustainability: Jute Fiber-Reinforced Bio-Based Sandwich Composites for Use in Battery Boxes2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 18, article id 3842Article in journal (Refereed)
    Abstract [en]

    The rising industrial demand for environmentally friendly and sustainable materials has shifted the attention from synthetic to natural fibers. Natural fibers provide advantages like affordability, lightweight nature, and renewability. Jute fibers’ substantial production potential and cost-efficiency have propelled current research in this field. In this study, the mechanical behavior (tensile, flexural, and interlaminar shear properties) of plasma-treated jute composite laminates and the flexural behavior of jute fabric-reinforced sandwich composites were investigated. Non-woven mat fiber (MFC), jute fiber (JFC), dried jute fiber (DJFC), and plasma-treated jute fiber (TJFC) composite laminates, as well as sandwich composites consisting of jute fabric bio-based unsaturated polyester (UPE) composite as facing material and polyethylene terephthalate (PET70 and PET100) and polyvinyl chloride (PVC) as core materials were fabricated to compare their functional properties. Plasma treatment of jute composite laminate had a positive effect on some of the mechanical properties, which led to an improvement in Young’s modulus (7.17 GPa) and tensile strength (53.61 MPa) of 14% and 8.5%, respectively, as well as, in flexural strength (93.71 MPa) and flexural modulus (5.20 GPa) of 24% and 35%, respectively, compared to those of JFC. In addition, the results demonstrated that the flexural properties of jute sandwich composites can be significantly enhanced by incorporating PET100 foams as core materials. © 2023 by the authors.

  • 4.
    Aulin, Christian
    et al.
    RISE Research Institutes of Sweden.
    Flodberg, Göran
    RISE Research Institutes of Sweden.
    Ström, Göran
    RISE Research Institutes of Sweden.
    Lindström, Tom S. C.
    RISE Research Institutes of Sweden.
    Enhanced mechanical and gas barrier performance of plasticized cellulose nanofibril films2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 1, p. 138-148Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNF) are mixed with plasticizers; sorbitol and glycerol, through high-pressure homogenization to prepare multifunctional biohybrid films. The resulting plasticized films obtained after solvent evaporation are strong, flexible and demonstrate superior toughness and optical transparency. The oxygen barrier properties of the biohybrid films outperform commercial packaging materials. The sorbitol-plasticized CNF films possess excellent oxygen barrier properties, 0.34 cm3·μm/m2·day·kPa at 50 % relative humidity, while significantly enhancing the toughness and fracture strength of the films. CNF films plasticized by 20 wt.% of sorbitol and glycerol could before rupture, be strained to about 9 % and 12 %, respectively. The toughness of the plasticized films increased by ca. 300 % compared to the pristine CNF film. Furthermore, the water vapor barrier properties of the biohybrid films were also preserved by the addition of sorbitol. CNF films plasticized with sorbitol was demonstrated to simultaneously enhance fracture toughness, work of fracture, softening behavior while preserving gas barrier properties. Highly favorable thermomechanical characteristics were found with CNF/sorbitol combinations and motivate further work on this material system, for instance as a thermoformable matrix in biocomposite materials. The unique combination of excellent oxygen barrier behavior, formability and optical transparency suggest the potential of these CNF-based films as an alternative in flexible packaging of oxygen sensitive devices like thin-film transistors or organic light-emitting diode displays, gas storage applications and as barrier coatings/laminations in packaging applications, including free-standing films as aluminium-replacement in liquid board and primary packaging, as replacement for polyethylene (PE) in wrapping paper, e. g. sweats and confectionary.

  • 5.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Pretreatment-dependent surface chemistry of wood nanocellulose for pH-sensitive hydrogels2014In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 3, no 29, p. 423-432Article in journal (Refereed)
    Abstract [en]

    Nanocellulose from wood is a promising material with potential in various technological areas. Within biomedical applications, nanocellulose has been proposed as a suitable nano-material for wound dressings. This is based on the capability of the material to self-assemble into 3D micro-porous structures, which among others have an excellent capacity of maintaining a moist environment. In addition, the surface chemistry of nanocellulose is suitable for various applications. First, OH-groups are abundant in nanocellulose materials, making the material strongly hydrophilic. Second, the surface chemistry can be modified, introducing aldehyde and carboxyl groups, which have major potential for surface functionalization. In this study, we demonstrate the production of nanocellulose with tailor-made surface chemistry, by pre-treating the raw cellulose fibres with carboxymethylation and periodate oxidation. The pre-treatments yielded a highly nanofibrillated material, with significant amounts of aldehyde and carboxyl groups. Importantly, the poly-anionic surface of the oxidized nanocellulose opens up for novel applications, i.e. micro-porous materials with pH-responsive characteristics. This is due to the swelling capacity of the 3D micro-porous structures, which have ionisable functional groups. In this study, we demonstrated that nanocellulose gels have a significantly higher swelling degree in neutral and alkaline conditions, compared to an acid environment (pH 3). Such a capability can potentially be applied in chronic wounds for controlled and intelligent release of antibacterial components into biofilms.

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  • 6.
    Das, Atanu Kumar
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. Swedish University of Agricultural Sciences, Sweden.
    Islam, Md Nazrul
    Khulna University, Bangladesh.
    Developments of nanocomposites in supercapacitor applications2023In: Nanocomposites-Advanced Materials for Energy and Environmental Aspects / [ed] Mohammad Ehtisham Khan, Jeenat Aslam and Chandrabhan Verma, Elsevier , 2023Chapter in book (Other academic)
    Abstract [en]

    Energy demand is increasing due to the development of modern society. The use of electronic devices including portable ones is increasing gradually. Thus it is influencing the development of supercapacitors for energy storage due to their 10–100 times higher energy storage capacity. At the same time, the implication of biobased material is being considered as environmentally friendly. Cellulose is the most abundant natural renewable biomaterial. Nanocellulose obtained from cellulose possesses special mechanical and electrochemical properties that are being applied for the fabrication of supercapacitors, such as their low-cost and high conductivity and their inexpensive and environment-friendly natures. The development strategy and performance are discussed for better understanding. The work undertaken on improving the fabrication of supercapacitors from cellulose-based nanocomposites will also be summarized.

  • 7.
    Das, Atanu Kumar
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. Swedish University of Agricultural Sciences, Sweden.
    Islam, Md. Nazrul
    Khulna University, Bangladesh.
    Faruk, Md Omar
    Khulna University, Bangladesh.
    Ashaduzzaman, Md
    Khulna University, Bangladesh.
    Dungani, Rudi;
    Institut Teknologi Bandung, Indonesia.
    Review on tannins: Extraction processes, applications and possibilities2020In: South African Journal of Botany, Vol. 135, p. 58-70Article in journal (Refereed)
    Abstract [en]

    Tannins are found in most of the species throughout the plant kingdom, where their functions are to protect the plant against predation and might help in regulating the plant growth. There are two major groups of tannins, i.e., hydrolyzable and condensed tannins. The tannins are being used as important and effective chemicals for the tanning of animal hides in the leather processing industry since the beginning of the industry. Additionally, the tannins have been using as mineral absorption and protein precipitation purposes since 1960s. These are also used for iron gall ink production, adhesive production in wood-based industry, anti-corrosive chemical production, uranium recovering chemical from seawater, and removal of mercury and methylmercury from solution. Presently, tannins are considering as bioactive compound in nutrition science. It has also been considered for advanced applications, i.e., 3D printing and biomedical devices. The application of tannins as medicine is another new dimension in medical science. This paper outlines the general information about tannins followed by their extraction process. The utilization of tannins has also been presented in a broader scale. Depending on all these information, the article also describes the impending utilization of tannins for ensuring high-sustainability and better environmental performance. 

  • 8.
    Fjellgaard Mikalsen, Ragni
    RISE - Research Institutes of Sweden, Safety and Transport, Fire Research Norway. Western Norway University of Applied Sciences, Norway; Otto von Guericke University Magdeburg, Germany.
    Fighting flameless fires: Initiating and extinguishing self-sustainedsmoldering fires in wood pellets2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Smoldering fires represent domestic, environmental and industrial hazards. This flameless form of combustion is more easily initiated than flaming, and is also more persistent and difficult to extinguish. The growing demand for non-fossil fuels has increased the use of solid biofuels such as biomass. This represents a safety challenge, as biomass self-ignition can cause smoldering fires, flaming fires or explosions.

    Smoldering and extinguishment in granular biomass was studied experimentally. The set-up consisted of a cylindrical fuel container of steel with thermally insulated side walls. The container was closed at the bottom, open at the top and heated from below by a hot surface. Two types of wood pellets were used as fuel, with 0.75-1.5 kg samples.

    Logistic regression was used to determine the transition region between non-smoldering and self-sustained smoldering experiments, and to determine the influence of parameters. Duration of external heating was most important for initiation of smoldering. Sample height was also significant, while the type of wood pellet was near-significant and fuel container height was not.

    The susceptibility of smoldering to changes in air supply was studied. With a small gap at the bottom of the fuel bed, the increased air flow in the same direction as the initial smoldering front (forward air flow) caused a significantly more intense combustion compared to the normal set-up with opposed air flow.

    Heat extraction from the combustion was studied using a water-cooled copper pipe. Challenges with direct fuel-water contact (fuel swelling, water channeling and runoff) were thus avoided. Smoldering was extinguished in 7 of 15 cases where heat extraction was in the same range as the heat production from combustion. This is the first experimental proof-of-concept of cooling as an extinguishment method for smoldering fires.

    Marginal differences in heating and cooling separated smoldering from extinguished cases; the fuel bed was at a heating-cooling balance point. Lower cooling levels did not lead to extinguishment, but cooling caused more predictable smoldering, possibly delaying the most intense combustion. Also observed at the balance point were pulsating temperatures; a form of long-lived (hours), macroscopic synchronization not previously observed in smoldering fires.

    For practical applications, cooling could be feasible for prevention of temperature escalation from self-heating in industrial storage units. This study provides a first step towards improved fuel storage safety for biomass. 

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  • 9.
    Helberg, Ragne
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Torstensen, Jonathan
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Dai, Zhongde
    NTNU Norwegian University of Science and Technology, Norway.
    Janakiram, Saravanan
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Gregersen, Øyvind
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. NTNU Norwegian University of Science and Technology, Norway.
    Deng, Liyuan
    NTNU Norwegian University of Science and Technology, Norway.
    Nanocomposite membranes with high-charge and size-screened phosphorylated nanocellulose fibrils for CO2 separation2021In: Green Energy and Environment, ISSN 2096-2797, Vol. 6, no 4, p. 585-Article in journal (Refereed)
    Abstract [en]

    In this study, cellulose nanofibrils (CNF) of high charge (H-P-CNF) and screened size (H-P-CNF-S) were fabricated by increasing the charge of phosphorylated cellulose nanofibrils (P-CNFs) during the pre-treatment step of CNF production. Results show that the H-P-CNF have a significantly higher charge (3.41 mmol g−1) compared with P-CNF (1.86 mmol g−1). Centrifugation of H-P-CNF gave a supernatant with higher charge (5.4 mmol g−1) and a reduced size (H-P-CNF-S). These tailored nanocelluloses were added to polyvinyl alcohol (PVA) solutions and the suspensions were successfully coated on porous polysulfone (PSf) supports to produce thin-film nanocomposite membranes. The humid mixed gas permeation tests show that CO2 permeability increases for membranes with the addition of H-P-CNF-S by 52% and 160%, compared with the P-CNF/PVA membrane and neat PVA membrane, respectively. 

  • 10.
    Hägg, Linus
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Johansson, Dennis
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Vikberg, Tommy
    Luleå Technical University, Sweden.
    Influence of Fan Speed on Airflow distribution in a Scandinavian Drying Kiln2012Conference paper (Refereed)
    Abstract [en]

    From the beginning of the 90’s the development of drying kilns in Scandinavia has been focusing on increased drying capacity and also making the kilns more flexible in terms of handling differences in dimensions and initial moisture content. In order to facilitate the demand of higher airflows there has been an increase in circulation fan capacity. In a sawmill with modern kilns the fan capacity in a single batch kiln can be over 90 kW, making the drying kiln fans the single biggest consumer of electric power.Today, more and more sawmills are reviewing their consumption of electric power due to increasing prices. One way of reducing the consumption is to reduce the fan speed when the moisture content is so low that the drying rate is mainly limited by the diffusion properties of the wood and not the airflow. Since modern kilns are designed for high capacity fans there is a lack of knowledge of how a reduced fan speed affects the airflow distribution. This poses a risk of getting reduced quality of the final product due to increased moisture content variation in a batch.In this study the airflow has been measured inside an industrial drying kiln. For this study two experiments were done with 20 airflow gauges placed inside a kiln. During both experiments the kiln was fully loaded with pre dried Scotts pine (Pinus sylvestris) boards with a thickness of 50 mm. The reason for using pre-dried boards was simply that the gauge was not able to withstand the climate produced during a real process. In order to cover as much of the kiln as possible the gauges were distributed differently for the two experiments.The results show that about 30 % of the total airflow passes through the bolster spaces which are only about 20 % of the total flow area. This means that a notable volume of air might not be participating in drying of the boards.The results show also that the relative airflow distribution between the middle and the side of board stacks becomes more heterogeneous at a low fan speed. This trend is also seen for the relative distribution of airflow between bolster and sticker spaces.

  • 11.
    Islam, Md. Nazrul
    et al.
    Khulna University, Bangladesh.
    Liza, Afroza Akter
    Nanjing Forestry University, China.
    Dey, Moutusi
    Khulna University, Bangladesh.
    Das, Atanu Kumar
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. Swedish University of Agricultural Sciences, Sweden.
    Faruk, Md Omar
    Shushilan, Bangladesh.
    Khatun, Mst Liza
    Khulna University, Bangladesh.
    Ashaduzzaman, Md
    Khulna University, Bangladesh.
    Xi, Xuedong
    Southwest Forestry University, China.
    Bio-based composites from bagasse using carbohydrate enriched cross-bonding mechanism: A formaldehyde-free approach2024In: Carbohydrate Polymer Technologies and Applications, E-ISSN 2666-8939, Vol. 7, article id 100467Article in journal (Refereed)
    Abstract [en]

    In this study, cross-bonded self-binding and bone glue-bonded particleboards were manufactured from sugarcane (Saccharum officinarum L.) bagasse with different pre-treatments of particles. Six types of panels were manufactured from bagasse particles with and without bone glue. The physical, mechanical, and thermal properties of the panels were examined according to the standards. Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis (TG) were performed to investigate the changes in the chemical bonds and thermal stability of the fabricated composites, respectively. It was found that cross-bonded bagasse self-binding (TC) and bone glue-bonded (T3) panels fabricated from non-boiled bagasse particles showed higher physical and mechanical properties compared to the other types of panels. Non-boiled bagasse particles with bone glue panels showed the highest mechanical properties, i.e., modulus of rupture (MOR = 26.22 MPa), modulus of elasticity (MOE = 4302 MPa), tensile strength = 8.35 MPa, and hardness = 1.72 MPa. TC and T3 panels also showed higher thermal stability compared to the other types of panels. A new peak at 3331-3334 cm-1 for the N-H stretching vibration in the FTIR analysis represents the presence of bone glue in the cross-bonded particleboards. Thus, this research advances the production of formaldehyde-free bagasse particleboard, introducing the cross-bonding technique and sustainable bone glue.

  • 12.
    Jedvert, Kerstin
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF. Friedrich Schiller University Jena, Germany.
    Heinze, Thomas
    Friedrich Schiller University Jena, Germany.
    Cellulose modification and shaping – a review2017In: Journal of polymer engineering, ISSN 0334-6447, E-ISSN 2191-0340, Vol. 37, no 9, p. 845-860Article in journal (Refereed)
    Abstract [en]

    This review aims to present cellulose as a versatile resource for the production of a variety of materials, other than pulp and paper. These products include fibers, nonwovens, films, composites, and novel derivatized materials. This article will briefly introduce the structure of cellulose and some common cellulose derivatives, as well as the formation of cellulosic materials in the micro- and nanoscale range. The challenge with dissolution of cellulose will be discussed and both derivatizing and nonderivatizing solvents for cellulose will be described. The focus of the article is the critical discussion of different shaping processes to obtain a variety of cellulose products, from commercially available viscose fibers to advanced and functionalized materials still at the research level.

  • 13.
    Klemm, Dieter O.
    et al.
    KKF Polymers for Life, Germany.
    Lindström, Tom
    Stony Brook University, USA.
    Abitbol, Tiffany
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Kralisch, Dana
    Friedrich Schiller University Jena, Germany; JeNaCell GmbH, Germany .
    Chapter 1 - The nanocellulose family2021In: Nanocellulose Based Composites for Electronics, Elsevier , 2021Chapter in book (Other academic)
    Abstract [en]

    Cellulose is one of the most important natural raw materials and has been extensively used for more than 100 years in the form of paper and board materials, textiles, a large range of various cellulose derivatives, and many other applications. Over the past 15 years, fundamental research on novel cellulosic types has matured into several new fields of material and product development, which combine the outstanding properties of the natural product cellulose with the specific features of nanomaterials. Like other nanomaterials, these nanocelluloses are characterized by having at least one dimension in the nanometer range. The field of nanocellulosic materials is subdivided into three areas that differ significantly in terms of starting material, production method, and product properties. The members of the nanocellulose family are cellulose nanofibers (CNF), cellulose nanocrystals (CNC), and bacterial nanocellulose (BNC). The last one forms cellulose nano networks.

  • 14.
    Kotov, N.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Larsson, P. A.
    KTH Royal Institute of Technology, Sweden.
    Jain, K.
    KTH Royal Institute of Technology, Sweden.
    Abitbol, Tiffany
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Cernescu, A.
    Attocube systems AG, Germany.
    Wågberg, L.
    KTH Royal Institute of Technology, Sweden.
    Johnson, C. M.
    KTH Royal Institute of Technology, Sweden.
    Elucidating the fine-scale structural morphology of nanocellulose by nano infrared spectroscopy2023In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 302, article id 120320Article in journal (Refereed)
    Abstract [en]

    Nanoscale infrared (IR) spectroscopy and microscopy, enabling the acquisition of IR spectra and images with a lateral resolution of 20 nm, is employed to chemically characterize individual cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) to elucidate if the CNCs and CNFs consist of alternating crystalline and amorphous domains along the CNF/CNC. The high lateral resolution enables studies of the nanoscale morphology at different domains of the CNFs/CNCs: flat segments, kinks, twisted areas, and end points. The types of nanocellulose investigated are CNFs from tunicate, CNCs from cotton, and anionic and cationic wood-derived CNFs. All nano-FTIR spectra acquired from the different samples and different domains of the individual nanocellulose particles resemble a spectrum of crystalline cellulose, suggesting that the non-crystalline cellulose signal observed in macroscopic measurements of nanocellulose most likely originate from cellulose chains present at the surface of the nanocellulose particles. 

  • 15.
    Lindahl, Carl
    et al.
    University of Gothenburg, Sweden; Uppsala University, Sweden.
    Xia, Wei
    University of Gothenburg, Sweden; Uppsala University, Sweden.
    Engqvist, Håkan
    University of Gothenburg, Sweden; Uppsala University, Sweden.
    Snis, Anders
    University of Gothenburg, Sweden; Arcam AB, Sweden.
    Lausmaa, Jukka
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Medicinteknik. University of Gothenburg, Sweden.
    Palmquist, Anders
    University of Gothenburg, Sweden.
    Biomimetic calcium phosphate coating of additively manufactured porous CoCr implants2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 353, p. 40-47Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study the feasibility to use a biomimetic method to prepare biomimetic hydroxyapatite (HA) coatings on CoCr substrates with short soaking times and to characterize the properties of such coatings. A second objective was to investigate if the coatings could be applied to porous CoCr implants manufactured by electron beam melting (EBM). The coating was prepared by immersing the pretreated CoCr substrates and EBM implants into the phosphate-buffered solution with Ca2+ in sealed plastic bottles, kept at 60 °C for 3 days. The formed coating was partially crystalline, slightly calcium deficient and composed of plate-like crystallites forming roundish flowers in the size range of 300-500 nm. Cross-section imaging showed a thickness of 300-500 nm. In addition, dissolution tests in Tris-HCl up to 28 days showed that a substantial amount of the coating had dissolved, however, undergoing only minor morphological changes. A uniform coating was formed within the porous network of the additive manufactured implants having similar thickness and morphology as for the flat samples. In conclusion, the present coating procedure allows coatings to be formed on CoCr and could be used for complex shaped, porous implants made by additive manufacturing.

  • 16.
    Nissilä, Tuukka
    et al.
    University of Oulu, Finland.
    Wei, Jiayuan
    Luleå University of Technology, Sweden.
    Geng, Shiyu
    Luleå University of Technology, Sweden.
    Teleman, Anita
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Oksman, Kristiina
    Luleå University of Technology, Sweden;University of Toronto, Canada.
    Ice-templated cellulose nanofiber filaments as a reinforcement material in epoxy composites2021In: Nanomaterials, E-ISSN 2079-4991, Vol. 11, no 2, article id 490Article in journal (Refereed)
    Abstract [en]

    Finding renewable alternatives to the commonly used reinforcement materials in composites is attracting a significant amount of research interest. Nanocellulose is a promising candidate owing to its wide availability and favorable properties such as high Young’s modulus. This study addressed the major problems inherent to cellulose nanocomposites, namely, controlling the fiber structure and obtaining a sufficient interfacial adhesion between nanocellulose and a non-hydrophilic matrix. Unidirectionally aligned cellulose nanofiber filament mats were obtained via ice-templating, and chemical vapor deposition was used to cover the filament surfaces with an aminosilane before impregnating the mats with a bio-epoxy resin. The process resulted in cellulose nanocomposites with an oriented structure and a strong fiber–matrix interface. Diffuse reflectance infrared Fourier transform and X-ray photoelectron spectroscopy studies revealed the presence of silane on the filaments. The improved interface, resulting from the surface treatment, was observable in electron microscopy images and was further confirmed by the significant increase in the tan delta peak temperature. The storage modulus of the matrix could be improved up to 2.5-fold with 18 wt% filament content and was significantly higher in the filament direction. Wide-angle X-ray scattering was used to study the orientation of cellulose nanofibers in the filament mats and the composites, and the corresponding orientation indices were 0.6 and 0.53, respectively, indicating a significant level of alignment. © 2021 by the authors.

  • 17.
    Rana, Md Nasim
    et al.
    Khulna University, Bangladesh.
    Islam, Md Nazrul
    Khulna University, Bangladesh.
    Nath, Suresh Kumar
    Khulna University, Bangladesh.
    Das, Atanu Kumar
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. Swedish University of Agricultural Sciences, Sweden.
    Ashaduzzaman, Md
    Khulna University, Bangladesh.
    Shams, Md Iftekhar
    Khulna University, Bangladesh.
    Properties of low-density cement-bonded composite panels manufactured from polystyrene and jute stick particles2019In: Journal of Wood Science, Vol. 65, no 1, article id 53Article in journal (Refereed)
    Abstract [en]

    This study was conducted to evaluate the properties of cement-bonded composite (CBC) manufactured using jute stick particles and expanded polystyrene (EPS) beads to reduce the density of CBC for mitigating the main limitation of CBC in its applications. The CBCs were manufactured by using cement, jute stick particle, EPS and jute fiber by cold pressing having the pressure of 5 MPa and pressing time of 24 h. CBCs were also manufactured by replacing the jute stick particles with EPS beads, the processing conditions remaining the same. There were at least 5 replications for each type of board. Waste jute fibers were added for improving the degenerated mechanical properties of CBC caused by the addition of EPS beads. Important physical properties, i.e., density, water absorption (WA) and thickness swelling (TS) and mechanical properties, i.e., modulus of elasticity (MOE) and modulus of rupture (MOR) of the manufactured CBCs were tested following the Malaysian Standards. Higher percentage of EPS beads significantly reduced the density of CBCs and the lowest density (0.91 +/- 0.02 g/cm(3)) was found when the EPS beads replaced 30% jute stick particles. As expected, mechanical properties decreased with the gradual replacement of jute stick particles by EPS beads. However, the degraded mechanical properties significantly increased when waste jute fibers were added in the CBCs. Addition of EPS beads in CBCs reduced the density, which might increase the potentiality for the utilization of cement-bonded composites for various applications.

  • 18.
    Redlinger-Pohn, J. D.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Brouzet, Christophe
    KTH Royal Institute of Technology, Sweden; Treesearch, Sweden; Wallenberg Wood Science Centre, Sweden; Aix Marseille Univ, Sweden.
    Aulin, Christian
    RISE Research Institutes of Sweden.
    Engström, Åsa
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Riazanova, Anastasia
    Treesearch, Sweden.
    Holmqvist, Claes
    RISE Research Institutes of Sweden, Bioeconomy and Health, Pulp, Paper and Packaging.
    Lundell, Fredrik
    KTH Royal Institute of Technology, Sweden; Wallenberg Wood Science Centre, Sweden.
    Söderberg, L Daniel
    KTH Royal Institute of Technology, Sweden; Treesearch, Sweden; Wallenberg Wood Science Centre, Sweden.
    Mechanisms of Cellulose Fiber Comminution to Nanocellulose by Hyper Inertia Flows2022In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 10, no 2, p. 703-719Article in journal (Refereed)
    Abstract [en]

    Nanocelluloses are seen as the basis of high-performance materials from renewable sources, enabling a bio-based sustainable future. Unsurprisingly, research has initially been focused on the design of new material concepts and less on new and adapted fabrication processes that would allow large-scale industrial production and widespread societal impact. In fact, even the processing routes for making nanocelluloses and the understanding on how the mechanical action fibrillates plant raw materials, albeit chemically or enzymatically pre-treated, are only rudimentary and have not evolved significantly during the past three decades. To address the challenge of designing cellulose comminution processes for a reliable and predictable production of nanocelluloses, we engineered a study setup, referred to as Hyper Inertia Microfluidizer, to observe and quantify phenomena at high speeds and acceleration into microchannels, which is the underlying flow in homogenization. We study two different channel geometries, one with acceleration into a straight channel and one with acceleration into a 90° bend, which resembles the commercial equipment for microfluidization. With the purpose of intensification of the nanocellulose production process, we focused on an efficient first pass fragmentation. Fibers are strained by the extensional flow upon acceleration into the microchannels, leading to buckling deformation and, at a higher velocity, fragmentation. The treatment induces sites of structural damage along and at the end of the fiber, which become a source for nanocellulose. Irrespectively on the treatment channel, these nanocelluloses are fibril-agglomerates, which are further reduced to smaller sizes. In a theoretical analysis, we identify fibril delamination as failure mode from bending by turbulent fluctuations in the flow as a comminution mechanism at the nanocellulose scale. Thus, we argue that intensification of the fibrillation can be achieved by an initial efficient fragmentation of the cellulose in smaller fragments, leading to a larger number of damaged sites for the nanocellulose production. Refinement of these nanocelluloses to fibrils is then achieved by an increase in critical bending events, i.e., decreasing the turbulent length scale and increasing the residence time of fibrils in the turbulent flow. © 2022 The Authors.

  • 19.
    Rojas-Lema, Sandra
    et al.
    Universitat Politècnica de València, Spain.
    Nilsson, Klara
    SLU Swedish University of Agricultural Sciences, Sweden.
    Trifol, Jon
    KTH Royal Institute of Technology, Sweden.
    Langton, Maud
    SLU Swedish University of Agricultural Sciences, Sweden.
    Gomez-Caturla, Jaume
    Universitat Politècnica de València, Spain.
    Balart, Rafael
    Universitat Politècnica de València, Spain.
    Garcia-Garcia, Daniel
    Universitat Politècnica de València, Spain.
    Moriana Torro, Rosana
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design. SLU Swedish University of Agricultural Sciences, Sweden; KTH Royal Institute of Technology, Sweden.
    “Faba bean protein films reinforced with cellulose nanocrystals as edible food packaging material”2021In: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 121, article id 107019Article in journal (Refereed)
    Abstract [en]

    In the present work, transparent films were obtained by the solution casting method from faba bean protein isolate (FBP), reinforced with different cellulose nanocrystals (CNCs) content (1, 3, 5 and 7 wt%), obtained by acid hydrolysis of pine cone, and using glycerol as plasticizer. The influence of different CNCs loadings on the mechanical, thermal, barrier, optical, and morphological properties was discussed. Microstructurally, the FTIR and FESEM results corroborated the formation of intramolecular interactions between the CNCs and proteins that lead to more compact and homogeneous films. These interactions had a positive influence on the mechanical strength properties, which is reflected in higher tensile strength and Young's modulus in reinforced films with respect to the control film, resulting in stiffer films as the CNCs content increases. Thermal stability of the FBP films was also improved with the presence of CNCs, by increasing the characteristic onset degradation temperature. In addition, the linkages formed between the CNCs, and proteins reduced the water affinity of the reinforced films, leading to a reduction in their moisture content and water solubility, and an increase in their water contact angle, obtaining more hydrophobic films as the CNCs content in the matrix increased. The addition of CNCs in the FBP film also considerably improved its barrier properties, reducing its water vapour transmission rate (WVTR) and oxygen transmission rate (OTR). The present work shows the possibility of obtaining biobased and biodegradable films of CNC-reinforced FBP with improved mechanical, thermal and barrier properties, and low water susceptibility, which can be of great interest in the food packaging sector as edible food packaging material.

  • 20.
    Torres, Elena
    et al.
    AITEX Textile Industry Research Association, Spain.
    Gaona, Aide
    AITEX Textile Industry Research Association, Spain.
    García-Bosch, Nadia
    AITEX Textile Industry Research Association, Spain.
    Muñoz, Miguel
    AITEX Textile Industry Research Association, Spain.
    Fombuena, Vicent
    Universitat Politècnica de València, Spain.
    Moriana Torro, Rosana
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Vallés-Lluch, Ana
    Universitat Politècnica de València, Spain.
    Improved Mechanical, Thermal, and Hydrophobic Properties of PLA Modified with Alkoxysilanes by Reactive Extrusion Process2021In: Polymers, E-ISSN 2073-4360, Vol. 13, no 15, article id 2475Article in journal (Refereed)
    Abstract [en]

    An eco-friendly strategy for the modification of polylactic acid (PLA) surface properties, using a solvent-free process, is reported. Reactive extrusion (REX) allowed the formation of new covalent bonds between functional molecules and the PLA polymeric matrix, enhancing its mechanical properties and modifying surface hydrophobicity. To this end, the PLA backbone was modified using two alkoxysilanes, phenyltriethoxysilane and N-octyltriethoxysilane. The reactive extrusion process was carried out under mild conditions, using melting temperatures between 150 and 180 °C, 300 rpm as screw speed, and a feeding rate of 3 kg·h−1. To complete the study, flat tapes of neat and functionalized PLA were obtained through monofilament melt extrusion to quantify the enhancement of mechanical properties and hydrophobicity. The results verified that PLA modified with 3 wt% of N-octyltriethoxysilane improves mechanical and thermal properties, reaching Young’s modulus values of 4.8 GPa, and PLA hydrophobic behavior, with values of water contact angle shifting from 68.6° to 82.2°.

  • 21.
    Vikberg, Tommy
    et al.
    Luleå Technical University, Sweden.
    Hansson, Lars
    Luleå Technical University, Sweden.
    Sterley, Magdalena
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Moisture movements during drying of green glued glulam beams from Norway spruce sideboards2012Conference paper (Refereed)
    Abstract [en]

    Form defects such as cup, crook, twist and bow, often causes low volumetric and economical yield in dried sideboards of Norway spruce. The high stiffness and density of sideboards, however, make them attractive to use as structural timber. The green gluing process i.e. gluing of unseasoned timber (with the subsequent drying) can make gluing of side boards efficient and can overcome the difficulties in utilization of side boards for structural applications.In present work, a study where computed tomography was used to monitor the drying process of a green glued glulam beam is presented. The beam had a dimension in cross-section of approximately 105×235 mm2 and consisted of eleven sideboards, planed and flat wise glued together with a 1-component polyurethane adhesive. After curing, and prior to drying, the beam was split into two halves, of approximate size of 50×235 mm2.The drying took place in a small drying kiln and computed tomography scanning was done every second hour throughout the drying process to get the density distribution in the beam. When the drying was finished the temperature in the kiln was increased to 103°C and kept for 24 hours, as to get a dry density reference. By use of an algorithm for subtracting the dry density, the moisture evaporation throughout the drying process could be estimated. Despite the harsh drying conditions, with a wet bulb depression of 10°C already from the start of the drying process, no formation of cracks or other quality problems could be seen in the process. Neither could any moisture gradient from the outer to the inner boards be detected.

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