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  • 1. Acciaro, R.
    et al.
    Aulin, C.
    RISE., Innventia.
    Wågberg, L.
    Lindström, T.
    RISE., Innventia.
    Claesson, P.M.
    Varga, I.
    Investigation of the formation structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels2011Inngår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, nr 4, s. 1369-1377Artikkel i tidsskrift (Fagfellevurdert)
  • 2.
    Akbari, Saeed
    et al.
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Sakhaei, A. H.
    University of Kent, UK.
    Panjwani, S.
    Singapore University of Technology and Design, Singapore.
    Kowsari, K.
    Singapore University of Technology and Design, Singapore.
    Ge, Q.
    Southern University of Science and Technology, China.
    Shape memory alloy based 3D printed composite actuators with variable stiffness and large reversible deformation2021Inngår i: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 321, artikkel-id 112598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soft composite actuators can be fabricated by embedding shape memory alloy (SMA) wires into soft polymer matrices. Shape retention and recovery of these actuators are typically achieved by incorporating shape memory polymer segments into the actuator structure. However, this requires complex manufacturing processes. This work uses multimaterial 3D printing to fabricate composite actuators with variable stiffness capable of shape retention and recovery. The hinges of the bending actuators presented here are printed from a soft elastomeric layer as well as a rigid shape memory polymer (SMP) layer. The SMA wires are embedded eccentrically over the entire length of the printed structure to provide the actuation bending force, while the resistive wires are embedded into the SMP layer of the hinges to change the temperature and the bending stiffness of the actuator hinges via Joule heating. The temperature of the embedded SMA wire and the printed SMP segments is changed sequentially to accomplish a large bending deformation, retention of the deformed shape, and recovery of the original shape, without applying any external mechanical force. The SMP layer thickness was varied to investigate its effect on shape retention and recovery. A nonlinear finite element model was used to predict the deformation of the actuators. 

  • 3.
    Alipour, Nazanin
    et al.
    KTH Royal Institute of Technology, Sweden.
    Strömberg, Emma
    KTH Royal Institute of Technology, Sweden.
    Enebro, Jonas
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Hedenqvist, Mikael
    KTH Royal Institute of Technology, Sweden.
    Release of micro- and nanoparticles from a polypropylene/clay nanocomposite, a methodology for controlled degradation and evaluation2021Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 319, artikkel-id 128761Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A methodology was developed for qualitative assessment and characterisation of particle losses from nanocomposites during service life. The methodology can be generalised to other systems where the material fragments during ageing and can be extended to quantitative analysis. A chamber was constructed for ageing of selected materials, which enabled effective collection and subsequent analysis of released particles. A combination of scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy was found to be suitable for characterising particles in terms of size, shape and content. The methodology was tested on a common nanoclay composite with polypropylene as the matrix. There was no need for physical/mechanical wear to generate particles, slow flow of air and elevated temperature led to cracking and fragmentation of the material, and subsequent release of nanocomposite particles containing embedded or protruding clay. The release of pure clay particles and polypropylene particles was also detected. Using the methodology, it was observed that even in ‘mild’ degradation conditions (pure thermo-oxidation with no wear), fillers and nanocomposite particles can be released to the environment, which is an environmental and health concern. © 2021 The Authors

  • 4.
    Al-Maqdasi, Zainab
    et al.
    Luleå University of Technology, Sweden.
    Pupure, Liva
    Luleå University of Technology, Sweden; Riga Technical University, Latvia.
    Gong, Guan
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Emami, Nazanin
    Luleå University of Technology, Sweden.
    Joffe, Roberts
    Luleå University of Technology, Sweden.
    Time-dependent properties of graphene nanoplatelets reinforced high-density polyethylene2021Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 138, nr 30, artikkel-id 50783Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deformation of polymers at constant applied stress is one of their major drawbacks, limiting their use in advanced applications. The study of this property using classical techniques requires extensive testing over long periods of time. It is well known that reinforced polymers show improved behavior over time compared to their neat counterparts. In this study, the effect of adding different amounts of graphene nanoplatelets (GNPs) on the time-dependent properties of high-density polyethylene (HDPE) is investigated using short-term creep tests and load/unload recovery tests. The results are discussed in terms of the test profile and the influence of loading history. Viscoplasticity/viscoelasticity analysis is performed using Zapas model and by comparing creep, creep compliance and pure viscoelasticity curves. The results show that the reinforcement of 15 wt% GNP have the most significant effect on the time-dependent behavior, reducing the strain by more than 50%. The creep compliance curves show that nano-reinforced HDPE behaves nonlinearly viscoelastically even at very low stresses. In addition to demonstrating the effect of nano-reinforcement, the discussion of the results concludes that the influence of loading history can be quite significant and should not be neglected in the design and evaluation of material behavior. © 2021 The Authors.

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  • 5.
    Almgren, K. M.
    et al.
    RISE., STFI-Packforsk.
    Kerholm, M.
    RISE., STFI-Packforsk.
    Gamstedt, E. K.
    RISE., STFI-Packforsk.
    Salmen, Lennart
    RISE., STFI-Packforsk.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Effects of moisture on dynamic mechanical properties of wood fiber composites studied by dynamic FT-IR spectroscopy2008Inngår i: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 27, nr 16-17, s. 1709-1721Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood fiber reinforced polylactide is a biodegradable composite where both fibers and matrix are from renewable resources. In the development of such new materials, information on mechanical behavior on the macroscopic and the molecular level is useful. In this study, dynamic Fourier transform infrared (FT-IR) spectroscopy is used to measure losses at the molecular level during cyclic tensile loading for bonds that are characteristic of the cellulosic fibers and the polylactid matrix. This molecular behavior is compared with measured macroscopic hysteresis losses for different moisture levels. The results show that moisture ingress will transfer the load from the fibers to the matrix, and that a more efficient fiber-matrix interface would diminish mechanical losses. Although the dynamic FT-IR spectroscopy method is still qualitative, this investigation shows that it can provide information on the stress transfer of the constituents in wood fiber reinforced plastics.

  • 6.
    Almgren, Karin M.
    et al.
    RISE., STFI-Packforsk.
    Gamstedt, E. Kristofer
    RISE., STFI-Packforsk.
    Berthold, Fredrik
    RISE., STFI-Packforsk.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Moisture uptake and hygroexpansion of wood fiber composite materials with polylactide and polypropylene matrix materials2009Inngår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 30, nr 12, s. 1809-1816Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effects of butantetracarboxylic acid (BTCA) modification, choice of matrix, and fiber volume fraction on hygroexpansion of wood fiber composites have been investigated. Untreated reference wood fibers and BTCA-modified fibers were used as reinforcement in composites with matrices composed of polylactic acid (PLA), polypropylene (PP), or a mixture thereof. The crosslinking BTCA modification reduced the out-of- plane hygroexpansion of PLA and PLA/PP composites, under water-immersed and humid conditions, whereas the swelling increased when PP was used as matrix material. This is explained by difficulties for the BTCA- modified fibers to adhere to the PP matrix. Fiber volume fraction was the most important parameter as regards out-of-plane hygroexpansion, with a high-fiber fraction leading to large hygroexpansion. Fiber-matrix wettability during processing and consolidation also showed to have a large impact on the dimensional stability and moisture uptake.

  • 7.
    Almgren, Karin M.
    et al.
    RISE., STFI-Packforsk.
    Gamstedt, E. Kristofer
    RISE., STFI-Packforsk.
    Nygård, P.
    Malmberg, F.
    Lindblad, J.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Role of fibre-fibre and fibre-matrix adhesion in stress transfer in composites made from resin-impregnated paper sheets2009Inngår i: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 29, nr 5, s. 551-557Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Paper-reinforced plastics are gaining increased interest as packaging materials, where mechanical properties are of great importance. Strength and stress transfer in paper sheets are controlled by fibre-fibre bonds. In paper-reinforced plastics, where the sheet is impregnated with a polymer resin, other stress-transfer mechanisms may be more important. The influence of fibre-fibre bonds on the strength of paper-reinforced plastics was therefore investigated. Paper sheets with different degrees of fibre-fibre bonding were manufactured and used as reinforcement in a polymeric matrix. Image analysis tools were used to verify that the difference in the degree of fibre-fibre bonding had been preserved in the composite materials. Strength and stiffness of the composites were experimentally determined and showed no correlation to the degree of fibre-fibre bonding, in contrast to the behaviour of unimpregnated paper sheets. The degree of fibre-fibre bonding is therefore believed to have little importance in this type of material, where stress is mainly transferred through the fibre-matrix interface.

  • 8.
    Almgren, K.M.
    et al.
    RISE., Innventia.
    Gamstedt, E.K.
    RISE., Innventia.
    Characterization of interfacial stress transfer ability by dynamic mechanical analysis of cellulose fiber based composite materials2010Inngår i: Composite interfaces (Print), ISSN 0927-6440, E-ISSN 1568-5543, Vol. 17, nr 9, s. 845-861Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The stress transfer ability at the fiber-matrix interface of wood fiber composites is known to affect the mechanical properties of the composite. The evaluation of interface properties at the level of individual fibers is however difficult due to the small dimensions and variability of the fibers. The dynamical mechanical properties of composite and constituents, in this case wood fibers and polylactide matrix, was here used together with micromechanical modeling to quantify the stress transfer efficiency at the fiber-matrix interface. To illustrate the methodology, a parameter quantifying the degree of imperfection at the interface was identified by inverse modeling using a micromechanical viscoelastic general self-consistent model with an imperfect interface together with laminate analogy on the composite level. The effect of moisture was assessed by comparison with experimental data from dynamic mechanical analysis in dry and moist state. For the wood fiber reinforced polylactide, the model shows that moisture absorption led to softening and mechanical dissipation in the hydrophilic wood fibers and biothermoplastic matrix, rather than loss of interfacial stress transfer ability.

  • 9.
    Ansari, Farhan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sjöstedt, Anna
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Hierarchical wood cellulose fiber/epoxy biocomposites: Materials design of fiber porosity and nanostructure2015Inngår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 74, s. 60-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Delignified chemical wood pulp fibers can be designed to have a controlled structure of cellulose fibril aggregates to serve as porous templates in biocomposites with unique properties. The potential of these fibers as reinforcement for an epoxy matrix (EP) was investigated in this work. Networks of porous wood fibers were impregnated with monomeric epoxy and cured. Microscopy images from ultramicrotomed cross sections and tensile fractured surfaces were used to study the distribution of matrix inside and around the fibers - at two different length scales. Mechanical characterization at different relative humidity showed much improved mechanical properties of biocomposites based on epoxy-impregnated fibers and they were rather insensitive to surrounding humidity. Furthermore, the mechanical properties of cellulose-fiber biocomposites were compared with those of cellulose-nanofibril (CNF) composites; strong similarities were found between the two materials. The reasons for this, some limitations and the role of specific surface area of the fiber are discussed.

  • 10.
    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, Material och produktion, Polymera material och kompositer.
    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 Boxes2023Inngår i: Polymers, E-ISSN 2073-4360, Vol. 15, nr 18, artikkel-id 3842Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11.
    Aulin, Christian
    et al.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Salazar-Alvarez, German
    KTH Royal Institute of Technology, Sweden; Stockholm University, Sweden.
    Lindström, Tom
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    High strength flexible and transparent nanofibrillated cellulose-nanoclay biohybrid films with tunable oxygen and water vapor permeability2012Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 4, nr 20, s. 6622-6628Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel, technically and economically benign procedure to combine vermiculite nanoplatelets with nanocellulose fibre dispersions into functional biohybrid films is presented. Nanocellulose fibres of 20 nm diameters and several micrometers in length are mixed with high aspect ratio exfoliated vermiculite nanoplatelets through high-pressure homogenization. The resulting hybrid films obtained after solvent evaporation are stiff (tensile modulus of 17.3 GPa), strong (strength up to 257 MPa), and transparent. Scanning electron microscopy (SEM) shows that the hybrid films consist of stratified nacre-like layers with a homogenous distribution of nanoplatelets within the nanocellulose matrix. The oxygen barrier properties of the biohybrid films outperform commercial packaging materials and pure nanocellulose films showing an oxygen permeability of 0.07 cm3 μm m-2 d-1 kPa -1 at 50% relative humidity. The oxygen permeability of the hybrid films can be tuned by adjusting the composition of the films. Furthermore, the water vapor barrier properties of the biohybrid films were also significantly improved by the addition of nanoclay. The unique combination of excellent oxygen barrier behavior and optical transparency suggests the potential of these biohybrid materials as an alternative in flexible packaging of oxygen sensitive devices such as thin-film transistors or organic light-emitting diode displays, gas storage applications and as barrier coatings/laminations in large volume packaging applications.

  • 12.
    Berglin, Niklas
    et al.
    RISE., Innventia.
    von Schenck, Anna
    RISE., Innventia.
    Alriksson, Björn
    Hörnberg, Andreas
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Lindstedt, J
    Östman, J
    POLYNOL - chemical intermediates from renewable sources2014Konferansepaper (Fagfellevurdert)
  • 13.
    Butchosa, Nuria
    et al.
    KTH Royal Institute of Technology, Sweden.
    Brown, Christian J.L.
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Bulone, Vincent
    KTH Royal Institute of Technology, Sweden.
    Zhou, Q.
    KTH Royal Institute of Technology, Sweden.
    Nanocomposites of bacterial cellulose nanofibers and chitin nanocrystals: Fabrication, characterization and bacterial activity2013Inngår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, nr 12, s. 3404-3413Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An environmentally friendly approach was implemented for the production of nanocomposites with bactericidal activity, using bacterial cellulose (BC) nanofibers and chitin nanocrystals (ChNCs). The antibacterial activity of ChNCs prepared by acid hydrolysis, TEMPO-mediated oxidation or partial deacetylation of α-chitin powder was assessed and the structure of the ChNC nanoparticles was characterized by X-ray diffraction, atomic force microscopy, and solid-state 13C-NMR. The partially deacetylated ChNCs (D-ChNC) showed the strongest antibacterial activity, with 99 ± 1% inhibition of bacterial growth compared to control samples. Nanocomposites were prepared from BC nanofibers and D-ChNC by (i) in situ biosynthesis with the addition of D-ChNC nanoparticles in the culture medium of Acetobacter aceti, and (ii) post-modification by mixing D-ChNC with disintegrated BC in an aqueous suspension. The structure and mechanical properties of the BC/D-ChNC nanocomposites were characterized by Fourier transform infrared spectroscopy, elemental analysis, field-emission scanning electron microscopy, and an Instron universal testing machine. The bactericidal activity of the nanocomposites increased with the D-ChNC content, with a reduction in bacterial growth by 3.0 log units when the D-ChNC content was 50%. D-ChNC nanoparticles have great potential as substitutes for unfriendly antimicrobial compounds such as heavy metal nanoparticles and synthetic polymers to introduce antibacterial properties to cellulosic materials.

  • 14.
    Cameron, Christopher
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Saseendran, Sibin
    RISE Research Institutes of Sweden.
    Stig, Fredrik
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Rouhi, Mohammad
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer. National University of Singapore, Singapore.
    A rapid method for simulating residual stress to enable optimization against cure induced distortion2021Inngår i: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 55, nr 26, s. 3799-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper a rapid method for residual cure stress analysis from composite manufacturing is presented. The method uses a high-fidelity path-dependent cure kinetics subroutine implemented in ABAQUS to calibrate a linear elastic model. The path-dependent model accounts for the tool-part interaction, forming pressure, and the changing composite modulus during the rubbery phase of matrix curing. Results are used to calculate equivalent lamina-wise coefficients of thermal expansion (CTE) in 3 directions for a linear temperature analysis. The goal is to accurately predict distortions for large complex geometries as rapidly as possible for use in an optimization framework. A carbon-epoxy system is studied. Simple coupons and complex parts are manufactured and measured with a 3 D scanner to compare the manufactured and simulated distortion. Results are presented and the accuracy and limitations of the rapid simulation method are discussed with particular focus on implementation in a numerical optimization framework. © The Author(s) 2021.

  • 15.
    Chen, Fei
    et al.
    KTH Royal Institute of Technology, Sweden.
    Monnier, Xavier
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE., Innventia.
    Gedde, Ulf Wiel
    KTH Royal Institute of Technology, Sweden.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Wheat gluten/chitosan blends: A new biobased material2014Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 60, s. 186-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 μm wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 μm). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 μm and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.

  • 16.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioekonomi, PFI.
    Novel biocomposite engineering and bio-applications2018Inngår i: Bioengineering, ISSN 2306-5354, Vol. 5, nr 4, s. 80-Artikkel i tidsskrift (Annet vitenskapelig)
  • 17.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Gibadullin, Marat R.
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Micro-structural characterisation of homogeneous and layered MFC nano-composites2013Inngår i: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 44, nr 1, s. 331-338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The complementary capabilities of various characterisation methods for micro-structural assessment are demonstrated. The assessed structures were composed of unbleached microfibrillated cellulose (MFC) in combination with bleached and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) pre-treated MFC materials. The biodegradable nano-composites were thus characterised in detail, including laser profilometry, scanning electron microscopy (SEM) in high and low vacuum modes, and field-emission SEM. The distribution of the unbleached MFC materials was assessed by staining the unbleached MFC with osmium tetroxide (OsO4), which reacts with CC double bonds encountered in lignin. In addition, some properties of the MFC nano-composite films were tested, i.e. tensile properties, water wettability and oxygen permeability. In general, the group of characteristics of the nano-composite MFC films was better than the properties of the films made of the neat MFC qualities. This indicates that mixing complementary MFC qualities could give synergetic effects that are not exploited completely when using the MFC qualities separately. The study thus confirms the suitability of unbleached MFC materials as a component in multilayer structures, for example biodegradable packaging applications.

  • 18.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Brodin, Malin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Wood pulp fibres and nanocellulose: Characterization and application in biocomposite materials2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A composite can be defined as a material composed of two or more components having distinct morphology and chemistry, and giving synergetic effects. In this paper the term biocomposite is used, referring to i) a material having at least one bio-component (e.g. wood pulp fibres and nanofibrils) or ii) biomaterials intended for biomedical applications. The utilization of wood pulp fibres in composite materials has gained major interest during the last years. There are various wood pulp fibres that can be used as reinforcement in composites, e.g. thermo-mechanical pulp (TMP), chemi-thermo-mechanical pulp (CTMP) and kraft pulp fibres. Depending on the pulping process (TMP, CTMP or kraft pulp), the pulp fibres differ greatly with respect to the fibre morphology and chemistry. Kraft pulp fibres have been one of the most used raw materials for producing nanocellulose. Nanocellulose from wood refers to various cellulose nano-materials such as cellulose nanocrystals and nanofibrillated cellulose. Nanofibrillated cellulose is composed of a major fraction of structurally homogeneous nanofibrils having typical widths in the nanometre scale and lengths in the micrometre scale. Wood pulp fibres and nanofibrils have been proposed as reinforcement in composite materials. Some of the major motivations have been the potential improvements by using fibres and nanofibrillated materials with respect to e.g. strength, biodegradability and functionality. The purpose of the present work is to review some advances in biocomposite research and development, including three focus areas; structured biocomposites, flexible biocomposites and biomaterials.

  • 19.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Miettinen, A.
    Hendriks, C. L. L
    Gamstedt, K.
    Kataka, M.
    Structural characterisation of kraft pulp fibres and their nanofibrillated materials for biodegradable composite applications2011Inngår i: Nanocomposites and Polymers with Analytical Methods, InTech , 2011Kapittel i bok, del av antologi (Fagfellevurdert)
  • 20.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Solheim, Olav
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Lenes, Marianne
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Larsen, Åge G.
    SINTEF, Norway.
    A method for estimating the fibre length in fibre-PLA composites2013Inngår i: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 250, nr 1, s. 15-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood pulp fibres are an important component of environmentally sound and renewable fibre-reinforced composite materials. The high aspect ratio of pulp fibres is an essential property with respect to the mechanical properties a given composite material can achieve. The length of pulp fibres is affected by composite processing operations. This thus emphasizes the importance of assessing the pulp fibre length and how this may be affected by a given process for manufacturing composites. In this work a new method for measuring the length distribution of fibres and fibre fragments has been developed. The method is based on; (i) dissolving the composites, (ii) preparing the fibres for image acquisition and (iii) image analysis of the resulting fibre structures. The image analysis part is relatively simple to implement and is based on images acquired with a desktop scanner and a new ImageJ plugin. The quantification of fibre length has demonstrated the fibre shortening effect because of an extrusion process and subsequent injection moulding. Fibres with original lengths of >1 mm where shortened to fibre fragments with length of <200 μm. The shortening seems to be affected by the number of times the fibres have passed through the extruder, the amount of chain extender and the fraction of fibres in the polymer matrix.

  • 21. Cho, S.-W.
    et al.
    Gällstedt, M.
    RISE., Innventia.
    Johansson, E.
    Hedenqvist, M.S.
    Injection-molded nanocomposites and materials based on wheat gluten2011Inngår i: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, nr 1, s. 146-152Artikkel i tidsskrift (Fagfellevurdert)
  • 22. Cho, S.-W.
    et al.
    Gällstedt, Mikael
    RISE., Innventia.
    Hedenqvist, M.S.
    RISE., Innventia.
    Properties of wheat gluten/poly(lactic acid) laminates2010Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 58, nr 12, s. 7344-7350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laminates of compression-molded glycerol-plasticized wheat gluten (WG) films surrounded and supported by poly(lactic acid) (PLA) films have been produced and characterized. The objective was to obtain a fully renewable high gas barrier film with sufficient mechanical integrity to function in, for example, extrusion-coating paper/board applications. It was shown that the lamination made it possible to make films with a broad range of glycerol contents (0-30 wt %) with greater strength than single unsupported WG films. The low plasticizer contents yielded laminates with very good oxygen barrier properties. In addition, whereas the unsupported WG films had an immeasurably high water vapor transmission rate (WVTR), the laminate showed values that were finite and surprisingly, in several cases, also lower than that of PLA. Besides being a mechanical support (as evidenced by bending and tensile data) and a shield between the WG and surrounding moisture, the PLA layer also prevented the loss of the glycerol plasticizer from the WG layer. This was observed after the laminate had been aged on an "absorbing" blotting paper for up to 17 weeks. The interlayer adhesion (peel strength) decreased with decreasing glycerol content and increasing WG film molding temperature (130 °C instead of 110 °C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 °C) did not, however, have a major effect on the final peel strength.

  • 23.
    Cunha, Ana Gisela
    et al.
    KTH Royal Institute of Technology, Sweden.
    Zhou, Qi
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Topochemical acetylation of cellulose nanopaper structures for biocomposites: Mechanisms for reduced water vapour sorption2014Inngår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 4, s. 2773-2787Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Moisture sorption decreases dimensional stability and mechanical properties of polymer matrix biocomposites based on plant fibers. Cellulose nanofiber reinforcement may offer advantages in this respect. Here, wood-based nanofibrillated cellulose (NFC) and bacterial cellulose (BC) nanopaper structures, with different specific surface area (SSA), ranging from 0.03 to 173.3 m2/g, were topochemically acetylated and characterized by ATR-FTIR, XRD, solid-state CP/MAS 13C-NMR and moisture sorption studies. Polymer matrix nanocomposites based on NFC were also prepared as demonstrators. The surface degree of substitution (surface-DS) of the acetylated cellulose nanofibers is a key parameter, which increased with increasing SSA. Successful topochemical acetylation was confirmed and significantly reduced the moisture sorption in nanopaper structures, especially at RH = 53 %. BC nanopaper sorbed less moisture than the NFC counterpart, and mechanisms are discussed. Topochemical NFC nanopaper acetylation can be used to prepare moisture-stable nanocellulose biocomposites.

  • 24.
    Dahlman, Olof
    et al.
    RISE., Innventia.
    Larsson, Karolina
    RISE., Innventia.
    Thermoplastic wood hemicellulose-lactide graft-polymers and films2014Konferansepaper (Fagfellevurdert)
  • 25.
    Dahlman, Olof
    et al.
    RISE., Innventia.
    Larsson, Karolina
    RISE., Innventia.
    Thermoplastic wood hemicellulose-lactide graft-polymers and films2014Konferansepaper (Fagfellevurdert)
  • 26. Eita, M.
    et al.
    Arwin, H.
    Granberg, Hjalmar
    RISE., Innventia.
    Wågberg, L.
    Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films2011Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, nr 2, s. 566-572Artikkel i tidsskrift (Fagfellevurdert)
  • 27.
    Eliasson, Sara
    et al.
    Scania CV AB, Sweden; Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Karlsson Hagnell, Mathilda
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Wennhage, Per
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Barsoum, Zuheir
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    A Statistical Porosity Characterization Approach of Carbon-Fiber-Reinforced Polymer Material Using Optical Microscopy and Neural Network2022Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, nr 19, artikkel-id 6540Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The intensified pursuit for lightweight solutions in the commercial vehicle industry increases the demand for method development of more advanced lightweight materials such as Carbon-Fiber-Reinforced Composites (CFRP). The behavior of these anisotropic materials is challenging to understand and manufacturing defects could dramatically change the mechanical properties. Voids are one of the most common manufacturing defects; they can affect mechanical properties and work as initiation sites for damage. It is essential to know the micromechanical composition of the material to understand the material behavior. Void characterization is commonly conducted using optical microscopy, which is a reliable technique. In the current study, an approach based on optical microscopy, statistically characterizing a CFRP laminate with regard to porosity, is proposed. A neural network is implemented to efficiently segment micrographs and label the constituents: void, matrix, and fiber. A neural network minimizes the manual labor automating the process and shows great potential to be implemented in repetitive tasks in a design process to save time. The constituent fractions are determined and they show that constituent characterization can be performed with high accuracy for a very low number of training images. The extracted data are statistically analyzed. If significant differences are found, they can reveal and explain differences in the material behavior. The global and local void fraction show significant differences for the material used in this study and are good candidates to explain differences in material behavior. © 2022 by the authors.

  • 28.
    Eliasson, Sara
    et al.
    Scania, Sweden; Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Karlsson Hagnell, Mathilda
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Wennhage, Per
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Barsoum, Zuheir
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    An Experimentally Based Micromechanical Framework Exploring Effects of Void Shape on Macromechanical Properties2022Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, nr 12, artikkel-id 4361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A micromechanical simulation approach in a Multi-Scale Modeling (MSM) framework with the ability to consider manufacturing defects is proposed. The study includes a case study where the framework is implemented exploring a cross-ply laminate. The proposed framework highlights the importance of correct input regarding micromechanical geometry and void characteristics. A Representative Volume Element (RVE) model is developed utilizing true micromechanical geometry extracted from micrographs. Voids, based on statistical experimental data, are implemented in the RVE model, and the effects on the fiber distribution and effective macromechanical properties are evaluated. The RVE algorithm is robust and maintains a good surrounding fiber distribution around the implemented void. The local void fraction, void size, and void shape affect the effective micromechanical properties, and it is important to consider the phenomena of the effective mechanical properties with regard to the overall void fraction of an RVE and the actual laminate. The proposed framework has a good prediction of the macromechanical properties and shows great potential to be used in an industrial implementation. For an industrial implementation, weak spots and critical areas for a laminate on a macro-level are found through combining local RVEs. © 2022 by the authors. 

  • 29.
    Fall, Andreas
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, Bioraffinaderi och energi.
    Nanocellulose and graphene: promising hybrid materials2018Inngår i: Recent advances in cellulose nanotechnology research: production, characterization and applications, Trondheim: RISE PFI , 2018Konferansepaper (Fagfellevurdert)
  • 30. Fernandes, S.C.M.
    et al.
    Freire, C.S.R.
    Silvestre, A.J.D.
    Pascoal Neto, C.
    Gandini, A.
    Berglund, Lars A.
    Salmen, Lennart
    RISE., Innventia.
    Transparent chitosan films reinforced with a high content of nanofibrillated cellulose2010Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 81, nr 2, s. 394-401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports the preparation and characterization of nanocomposite films based on different chitosan matrices and nanofibrillated cellulose (NFC) for the purpose of improving strength properties. The nanocomposite films were prepared by a simple procedure of casting a water-based suspension of chitosan and NFC, and were characterized by several techniques: namely SEM, X-ray diffraction, visible spectrophotometry, TGA, tensile and dynamic-mechanical analysis. The films obtained were shown to be highly transparent (transmittance varying between 90 and 20% depending on the type of chitosan and NFC content), flexible, displayed better mechanical properties, with a maximum increment on the Young’s modulus of 78% and 150% for high molecular weight (HCH) and water-soluble high molecular weight (WSHCH) filled chitosans, respectively; and of 200% and 320% for low molecular weight (LCH) and water-soluble filled (WSLCH) chitosans, respectively. The filled films also showed increased thermal stability, with, for example, an increase in the initial degradation temperature (Tdi) from 227 °C in the unfilled LCH film up to 271 °C in filled LCHNFC50% nanocomposite films, and a maximum degradation temperature (Td1) raising from 304 °C to 313 °C for the same materials.

  • 31. Fernández, A.
    et al.
    Sánchez, M. D.
    Ankerfors, Mikael
    RISE., STFI-Packforsk.
    Lagaron, J. M.
    Effects of ionizing radiation in ethylene-vinyl alcohol copolymers and in composites containing microfibrillated cellulose2008Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 109, nr 1, s. 126-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study reports on the effect of gamma radiation on morphological, thermal, and water barrier properties of pure ethylene vinyl alcohol copolymers (EVOH29 and EVOH44) and its biocomposites with the nanofiller microfibrillated cellulose (2 wt%). Added microfibrillated cellulose (MFC) preserved the transparency of EVOH films but led to a decrease in water barrier properties. Gamma irradiation at low (30 kGy) and high doses (60 kGy) caused some irreversible changes in the phase morphology of EVOH29 and EVOH44 copolymers that could be associated to crosslinking and other chemical alterations. Additionally, the EVOH copolymers and the EVOH composites reduced the number of hygroscopic hydroxyl functionalities during the irradiation processing and novel carbonyl based chemistry was, in turn, detected. As a result of the above alterations, the water barrier properties of both neat materials and composites irradiated at low doses were notably enhanced, counteracting the detrimental effect on water barrier of adding MFC to the EVOH matrix. © 2008 Wiley Periodicals, Inc.

  • 32.
    Flansbjer, Mathias
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Honfi, Daniel
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Vennetti, Daniel
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Williams Portal, Natalie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Betong & Berg.
    Mueller, Urs
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Betong & Berg.
    Własak, Lech
    Mostostal Warszawa SA, Poland.
    Structural Concept of Novel RPC Sandwich Façade Elements with GFRP Connectors2016Inngår i: IABSE Congress Stockholm 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment. Report, IABSE c/o ETH Hönggerberg , 2016, s. 2164-2171Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The SESBE research project aims to develop novel smart sandwich façade elements with high insulating capabilities while providing a reduced thickness in conjunction with superior mechanical and durability properties. The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors in the façade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large façade elements, the performance of the connectors is critical for the entire structural concept. A description of structural performance and results based on experimental methods and finite element (FE) analysis are presented.

  • 33.
    Francis, Sachin
    et al.
    RISE Research Institutes of Sweden. Chalmers University of Technology, Sweden.
    Bru, Thomas
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Asp, Leif
    Chalmers University of Technology, Sweden.
    Wysocki, Maciej
    RISE Research Institutes of Sweden, Material och produktion.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Characterisation of tape-based carbon fibre thermoplastic discontinuous composites for energy absorption2021Inngår i: Plastics, rubber and composites, ISSN 1465-8011, E-ISSN 1743-2898, Vol. 50, nr 7, s. 351-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tape-based discontinuous composite is a relatively new type of composite material that offers improved mechanical properties for similar process-ability compared to Sheet Moulding Compound or Bulk Moulding Compound. This makes it potentially attractive for the automotive industry. In this paper, a thin-ply carbon fibre reinforced polypropylene-based discontinuous composite is studied. Mechanical tests are performed to obtain the tensile, compression and shear behaviour of the material. The energy absorption via tearing is also studied to assess the suitability of the material for energy absorption applications, such as crash-boxes. The tearing test results show a large degree of plastic deformation and an advancing damage front leading to higher specific energy absorption via tearing compared to conventional composite materials. © 2021 The Author(s). 

  • 34. Gamstedt, E.K.
    et al.
    Sandell, R.
    Berthold, F.
    RISE., Innventia.
    Pettersson, T.
    RISE., Innventia.
    Nordgren, N.
    Characterization of interfacial stress transfer ability of particulate cellulose composite materials2011Inngår i: Mechanics of materials, ISSN 0167-6636, E-ISSN 1872-7743, nr 11, s. 693-704Artikkel i tidsskrift (Fagfellevurdert)
  • 35.
    Ghanadpour, Maryam
    et al.
    KTH Royal Institute of Technology, Sweden.
    Carosio, Federico
    Polytechnic University of Turin, Italy.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Phosphorylated Cellulose Nanofibrils: A Renewable Nanomaterial for the Preparation of Intrinsically Flame-Retardant Materials2015Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, nr 10, s. 3399-3410Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose from wood fibers can be modified for use in flame-retardant composites as an alternative to halogen-based compounds. For this purpose, sulfite dissolving pulp fibers have been chemically modified by phosphorylation, and the resulting material has been used to prepare cellulose nanofibrils (CNF) that have a width of approximately 3 nm. The phosphorylation was achieved using (NH4)2HPO4 in the presence of urea, and the degree of substitution by phosphorus was determined by X-ray photoelectron spectroscopy, conductometric titration, and nuclear magnetic resonance spectroscopy. The presence of phosphate groups in the structure of CNF has been found to noticeably improve the flame retardancy of this material. The nanopaper sheets prepared from phosphorylated CNF showed self-extinguishing properties after consecutive applications of a methane flame for 3 s and did not ignite under a heat flux of 35 kW/m2, as shown by flammability and cone calorimetry measurements, respectively.

  • 36.
    Gonga, Guan
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea SICOMP AB.
    Li, Bin
    Wichita State University, USA.
    Dielectric properties of bionanocomposites2017Inngår i: Polymer Nanocomposites for Dielectrics, Pan Stanford Publishing Pte. Ltd. , 2017, s. 139-169Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Bionanocomposites represent an emerging group of nanostructured hybrid materials. Besides the structural and functional properties similar to conventional nanocomposites, the inherent properties, namely, biocompatibility and biodegradability, make these environmentally benign materials highly attractive for both academia and industry. Research on bionanocomposites is an interdisciplinary field that is closely related to packaging and biological systems, such as tissue engineering and drug delivery, and also extended to electronics, sensor, and energy applications, just to name a few. This chapter will give an overview on the research progress of self-assembled bionanocomposites and artificial nanocomposites composed of typical biopolymers and nanoparticles, which exhibit dielectric functions and can have promising potential to be used in biological, electronic, and energy storage applications. 7.1 IntroductionDwindling fossil resources and growing environmental concerns have led to increasing need for sustainable solutions. Overdependence on petroleum resources and environmental impact/carbon footprint can be alleviated by biomaterials development using biological resources or more precisely annually renewable resources. Bionanocomposites are formed by the polymer matrix and reinforcing phase, either of them or both based on renewable resources, and show at least one dimension on the nanometer scale. Bionanocomposites have been the subject of extensive research since the last two decades. These efforts have generated environment-friendly applications for many uses, such as for automotive, packaging, and household products, to name some [1]. Multifunctionality is a trend of development to expand the applications of bionanocomposites.Dielectric bionanocomposites can be utilized for various applications such as conductive elements, heating devices, electromagnetic interference, supercapacitor, shielding and antimicrobial elements, and bio-applications like those of tissue scaffolds for the replacement or restoration of damaged or malfunctioning tissue because a variety of tissue respond to electrical stimulation [2]. On the other hand, an accurate and comprehensive description of structures is of vital importance for the development of high-quality bionanocomposites, which is, however, very difficult because of their nature. Electrical conductivity depends on the micro-and macroscopic states of the composites and gives information on the interaction of individual components inside. Determining the electrical properties of a material is therefore one of the most convenient and sensitive methods for studying the structures of materials [3, 4]. The dielectric properties of bionanocomposites depend on the nature of biopolymer matrix and filler particles, the dimension (mainly include length-to-diameter or aspect ratio) and content of filler particles, and the interfacial characteristics. These issues are taken into consideration in this chapter when reviewing the dielectric performance of bionanocomposites. © 2017 by Pan Stanford Publishing Pte. Ltd.

  • 37.
    Gonçalves Nunes, Stephanie
    et al.
    Luleå University of Technology, Sweden; Riga Technical University, Latvia; Federal University of Rio Grande do Sul, Brazil.
    Saseendran, Sibin
    RISE Research Institutes of Sweden. Luleå University of Technology, Sweden.
    Fernberg, Patrik
    Luleå University of Technology, Sweden.
    Emami, Nazanin
    Luleå University of Technology, Sweden.
    Esposito, Antonella
    Normandie University, France.
    Campos Amico, Sandro
    Federal University of Rio Grande do Sul, Sandro.
    Varna, Janis
    Luleå University of Technology, Sweden; Riga Technical University, Latvia.
    SHIFT FACTOR DEPENDENCE ON PHYSICAL AGING AND TEMPERATURE FOR VISCOELASTIC RESPONSE OF POLYMERS2022Inngår i: ECCM 2022 - Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability, Composite Construction Laboratory (CCLab), Ecole Polytechnique Federale de Lausanne (EPFL) , 2022, s. 431-438Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As polymeric resins are used as matrix in reinforced composites, understanding of their viscoelastic-viscoplastic response is critical for long-term performance design. However, during service life, thermosets are not in a thermodynamic equilibrium state, resulting in physical aging, which affects failure and viscoelastic (VE) properties, becoming a concern for industries. In this paper, an alternative methodology for testing and parameter determination for aging polymer, at different temperatures (TA) and times (tA), is proposed. The experimental data analysis was performed using a Schapery's type thermo-aging-rheologically simple VE model with constant coefficients in Prony series and the effect of temperature and aging included by two shift factors (aT, aA). Results showed that the shift factor can be presented as the product of shifts aT and aA. Furthermore, for short tA the change rate of the aA with tA does not depend on TA, whereas for long tA at high TA the rate increases. 

  • 38.
    Halonen, Helena
    et al.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Iversen, Tommy
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Mercerized cellulose biocomposites: A study of influence of mercerization on cellulose supramolecular structure, water retention value and tensile properties2013Inngår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, nr 1, s. 57-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study the effect of the mercerization degree on the water retention value (WRV) and tensile properties of compression molded sulphite dissolving pulp was evaluated. The pulp was treated with 9, 10, or 11 % aqueous NaOH solution for 1 h before compression molding. To study the time dependence of mercerization the pulp was treated with 12 wt% aqueous NaOH for 1, 6 or 48 h. The cellulose I and II contents of the biocomposites were determined by solid state cross polarization/magic angle spinning carbon 13 nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy. By spectral fitting of the C6 and C1 region the cellulose I and II content, respectively, could be determined. Mercerization decreased the total crystallinity (sum of cellulose I and cellulose II content) and it was not possible to convert all cellulose I to cellulose II in the NaOH range investigated. Neither increased the conversion significantly with 12 wt% NaOH at longer treatment times. The slowdown of the cellulose I conversion was suggested as being the result from the formation of cellulose II as a consequence of coalescence of anti-parallel surfaces of neighboring fibrils (Blackwell et al. in Tappi 61:71-72, 1978; Revol and Goring in J Appl Polym Sci 26:1275-1282, 1981; Okano and Sarko in J Appl Polym Sci 30:325-332, 1985). Compression molding of the partially mercerized dissolving pulps yielded biocomposites with tensile properties that could be correlated to the decrease in cellulose I content in the pulps. Mercerization introduces cellulose II and disordered cellulose and lowered the total crystallinity reflected as higher water sensitivity (higher WRV values) and poorer stiffness of the mercerized biocomposites.

  • 39.
    Hartzen, Ann-Sofie Margareta
    et al.
    University of Gävle, Sweden; KTH Royal Institute of Technology, Sweden.
    Lindberg, Siv M.
    RISE., Innventia.
    The material expression of new pulp-fibre reinforced composites in relation to other material categories2016Inngår i: Proceedings - D and E 2016: 10th International Conference on Design and Emotion - Celebration and Contemplation, 2016, s. 191-200Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To help bridge the gap between the science lab and commercial production there is a need for a better understanding of how new bio-based materials are perceived by users. The aim of the studies in this paper was to identify the material expression, sensorial properties and semantic dimensions of a group of pulp-fibre reinforced composites that are still in the research phase and how these relate to other, better-known materials already on the market. The studies involved 21 different materials, divided into different material groups such as metals, solid woods, wood fibre materials, plastic and fibre-reinforced composites in which the pulp-fibre reinforced composites were included. The materials were evaluated for meaning in a product semantic study and for sensory perception in a sensorial study. The results of the semantic study gave two underlining dimensions explaining most of the variations between the materials, Quality and Naturalness. These dimensions also had strong correlations to some of the sensorial properties. The results indicate that the pulp-fibre reinforced composites were not perceived as having high quality or expressing naturalness. They were hard to distinguish from the plastics in the study. The implications for further research and material development are discussed.

  • 40.
    Jansson, Mikael
    et al.
    RISE., Innventia.
    Danielsson, Sverker
    RISE., Innventia.
    Edlund, U
    Albertsson, A-C
    Turnwood: barrier materials for packaging from wood hydrolysate2014Konferansepaper (Fagfellevurdert)
  • 41.
    Jin, Hua
    et al.
    Helsinki University of Technology, Finland.
    Cao, Anyuan
    Peking University, China.
    Shi, Enzheng
    Peking University, China.
    Seitsonen, Jani J.T.
    Aalto University, Finland.
    Zhang, Luhui
    Peking University, China.
    Ras, Robin H.A.
    Helsinki University of Technology, Finland.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Ankerfors, Mikael
    RISE., Innventia.
    Walther, Andreas
    RWTH Aachen University, Germany.
    Ikkala, Olli T.
    Helsinki University of Technology, Finland.
    Ionically interacting nanoclay and nanofibrillated cellulose lead to tough bulk nanocomposites in compression by forced self-assembly2013Inngår i: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, nr 6, s. 835-840Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several approaches have recently been shown for self-assembled biomimetic composite films, aiming at combinations of high toughness, strength, and stiffness. However, it remains challenging to achieve high toughness using simple processes especially for bulk materials. We demonstrate that ionically interacting cationic native nanofibrillated cellulose (C-NFC) and anionic nanoclay, i.e. montmorillonite (MTM), allow local self-assemblies by a simple centrifugation process to achieve 3D bulk materials. The composite with MTM/C-NFC of 63/37 w/w has a high compressive strain to failure of 37% with distinct plastic deformation behaviour, a high work to fracture of 23.1 MJ m-3, and a relatively high compression strength of 76 MPa. Unlike the conventionally used sequential deposition methods to achieve well-defined layers for the oppositely charged units as limited to films, the present one-step method allows quick formation of bulk materials and leads to local self-assemblies, however, having a considerable amount of nanovoids and defects between them. We suggest that the nanovoids and defects promote the plastic deformation and toughness. Considering the simple preparation method and bio-based origin of NFC, we expect that the present tough bulk nanocomposites in compression have potential in applications for sustainable and environmentally friendly materials in construction and transportation.

  • 42.
    Johansson, Ann-Christine
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Sott, Richard
    RISE Research Institutes of Sweden, Material och produktion, Kemi och Tillämpad mekanik.
    Mattsson, Cecilia
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Comparative study of thermochemical recycling with solvolysis and pyrolysis of End-of-Life wind turbine blades: Rekovind2 - WP32023Rapport (Annet vitenskapelig)
    Abstract [en]

    There is an urgent need for the development of viable recycling solutions for the increasing waste streams of glass fiber composites (GFRPs) from all sectors i.e. leisure boats, windmills and building constructions. Two potential recycling methods that can separate and recover both the polymers and the high-quality fibers from these kinds of materials are pyrolysis and solvolysis. In this project recycling of an epoxy-based Endof-Life wind turbine blade was evaluated in lab scale using the two methods. In previous literature the main focus has been on the quality of the fibers but in this project the main focus was to compare the chemical composition of the oil products. The produced oils from solvolysis and pyrolysis have been compared with a multianalysis approach by using elemental analysis, GC-MS, pyro-GC-MS/FID, 2D NMR (HSQC) for gaining more information about the chemical structure of the produced monomers (phenols), oligomers and polymers. Almost all the volatile matter in the End-of-Life wind turbine blade was recovered as pyrolysis oil, 36 wt.% yield. The solvolysis oil yield was lower, 17 wt.%, mainly due to a major part of the solvolysis oil ended up in the aqueous solvent. The composition of the oils from both technologies was analyzed based on both their volatile i.e. monomeric and polymeric content. The result point to that both methods produced oils with similar polymeric parts according to NMR and pyro-GC-MS/FID, based on an oxygenated aliphatic network connected with aromatic phenolic structures. Increased information of chemical oil composition will be useful for further processing as raw material in refineries/chemical industries. The monomeric part of the oil produced from pyrolysis was found in relatively large amounts, ~57 wt.%, and can be a future high-value product from recycling of wind turbine blades. The total recovery of phenolics from the pyrolysis was 18 wt.% of the wind turbine blade weight.

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  • 43. Johnson, O.
    et al.
    Lindberg, Siv M
    RISE., STFI-Packforsk.
    Roos, A.
    Hugosson, M.
    Lindström, Mikael
    RISE., STFI-Packforsk.
    Consumer perceptions and preferences on solid wood, wood-based panels, and composites: A repertory grid study2008Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 40, nr 4, s. 663-678Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Knowledge about consumer perception and preferences on solid wood, wood-based panels, and wood-based composites is important for product development and marketing. The aim of this study was to identify attributes and associations that people use to describe different types of wood materials and to explore how they relate to preferences. The study involved nine samples that were evaluated with the Kelly’s repertory grid technique and content analysis. Based on respondents’ answers, 19 core categories reflecting sample attributes were extracted. General preferences for each sample were also recorded. Principal component analysis generated two factors describing 1) naturalness, wood-likeness, softness, unprocessed origin, living, pleasant, and high value; and 2) solid and homogeneous impression. A third, preliminary factor included categories describing irregular pattern, sleekness, and smoothness. The wood samples were most liked, whereas composites and panels were not appreciated. Preferred core categories were naturalness, wood-likeness, smoothness, living impression, and value. The least liked core categories were processed, hard, and high weight. The implications of the results for product development and marketing are discussed. © 2008 by the Society of Wood Science and Technology.

  • 44.
    Josefsson, Gabriella
    et al.
    Uppsala University, Sweden.
    Berthold, Fredrik
    RISE., Innventia.
    Gamstedt, Erik Kristofer
    Uppsala University, Sweden.
    Stiffness contribution of cellulose nanofibrils to composite materials2014Inngår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 51, nr 5, s. 945-953Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocomposites, reinforced by different types of cellulose fibrils, have gained increased interest the last years due to the promising mechanical properties. There is a lack of knowledge about the mechanical properties of the cellulose fibrils, and their contribution to the often claimed potential of the impressive mechanical performance of the nanocomposites. This paper investigates the contribution from different types of cellulose nanofibril to the overall elastic properties of composites. A multiscale model is proposed, that allows back-calculation of the elastic properties of the fibril from the macroscopic elastic properties of the composites. The different types of fibrils used were nanofibrillated cellulose from wood, bacterial cellulose nano-whiskers and microcrystalline cellulose. Based on the overall properties of the composite with an unaged polylactide matrix, the effective longitudinal Young's modulus of the fibrils was estimated to 65 GPa for the nanofibrillated cellulose, 61 GPa for the nano whiskers and only 38 GPa for the microcrystalline cellulose. The ranking and absolute values are in accordance with other studies on nanoscale morphology and stiffness estimates. Electron microscopy revealed that in the melt-processed cellulose nanofibril reinforced thermoplastics, the fibrils tended to agglomerate and form micrometer scale platelets, effectively forming a microcomposite and not a nanocomposite. This dispersion effect has to be addressed when developing models describing the structure-property relations for cellulose nanofibril composites.

  • 45.
    Kaline P., Furlan
    Hamburg University, Germany.
    Diaz, Ana ()
    Paul Scherrer Institut, Switzerland.
    Holler, Mirko ()
    Paul Scherrer Institut, Switzerland.
    Krekeler, Tobias ()
    Hamburg University of Technology, Germany.
    Ritter, Martin ()
    Hamburg University of Technology, Germany.
    Petrov, Alexander Yu. ()
    Hamburg University of Technology, Germany; ITMO University, Russia.
    Eich, Manfred ()
    Hamburg University of Technology, Germany.
    Blick, Robert ()
    Hamburg University of Technology, Germany.
    Schneider, Gerold A. ()
    Hamburg University of Technology, Germany.
    Greving, Imke ()
    Hamburg University of Technology, Germany.
    Zierold, Robert ()
    Hamburg University of Technology, Germany.
    Janßen, Rolf ()
    Hamburg University of Technology, Germany.
    Photonic materials for high-temperature applications: Synthesis and characterization by X-ray ptychographic tomography2018Inngår i: Applied Materials Today, ISSN 2352-9407, Vol. 13, s. 359-369Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photonic materials for high-temperature applications need to withstand temperatures usually higher than 1000 °C, whilst keeping their function. When exposed to high temperatures, such nanostructured materials are prone to detrimental morphological changes, however the structure evolution pathway of photonic materials and its correlation with the loss of material's function is not yet fully understood. Here we use high-resolution ptychographic X-ray computed tomography (PXCT) and scanning electron microscopy (SEM) to investigate the structural changes in mullite inverse opal photonic crystals produced by a very-low-temperature (95 °C) atomic layer deposition (ALD) super-cycle process. The 3D structural changes caused by the high-temperature exposure were quantified and associated with the distinct structural features of the ceramic photonic crystals. Other than observed in photonic crystals produced via powder colloidal suspensions or sol-gel infiltration, at high temperatures of 1400 °C we detected a mass transport direction from the nano pores to the shells. We relate these different structure evolution pathways to the presence of hollow vertexes in our ALD-based inverse opal photonic crystals. Although the periodically ordered structure is distorted after sintering, the mullite inverse opal photonic crystal presents a photonic stopgap even after heat treatment at 1400 °C for 100 h.

  • 46.
    Karpenja, Tatjana
    et al.
    RISE., Innventia.
    Lorentzon, Ann
    RISE., Innventia.
    Wickholm, Kristina
    RISE., Innventia.
    Sustainability aspects in waste management of biocomposites2013Konferansepaper (Fagfellevurdert)
  • 47. Klemm, D.
    et al.
    Kramer, F.
    Moritz, S.
    Lindström, T.
    RISE., Innventia.
    Ankerfors, M.
    RISE., Innventia.
    Gray, D.
    Dorris, A.
    Nanocelluloses: A new family of nature-based materials2011Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, nr 24, s. 5438-5466Artikkel i tidsskrift (Fagfellevurdert)
  • 48. Kuktaite, R.
    et al.
    Plivelic, T.S.
    Cerenius, Y.
    Hedenqvist, M.S.
    Gällstedt, M.
    RISE., Innventia.
    Marttila, S.
    Ignell, R.
    Popineau, Y.
    Tranquet, O.
    Shewry, P.R.
    Johansson, E.
    Structure and morphology of wheat gluten films: From polymeric protein aggregates toward superstructure arrangements2011Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, nr 5, s. 1438-1448Artikkel i tidsskrift (Fagfellevurdert)
  • 49.
    Kuktaite, Ramune
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Ture, Hasan
    Ordu University, Turkey.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE., Innventia.
    Plivelic, Tomas S.
    Lund University, Sweden.
    Gluten biopolymer and nanoclay-derived structures in wheat gluten-urea-clay composites2014Inngår i: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 2, nr 6, s. 1439-1445Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here, we investigated the structure of natural montmorillonite (MMT) and modified Cloisite C15A (MMT pre-intercalated with a dimethyl-dehydrogenated tallow quaternary ammonium surfactant) nanoclays in the wheat gluten-urea matrix in order to obtain a nanocomposite with improved barrier and mechanical properties. Small-angle X-ray scattering indicated that the characteristic hexagonal closed packed structure of the wheat gluten-urea matrix was not found in the C15A system and existed only in the 3 and 5 wt % MMT composites. SAXS/WAXS, TGA, and water vapor/oxygen barrier properties indicated that the dispersion of the C15A clay was somewhat better than the natural MMT clay. Confocal laser scanning microscopy showed MMT clay clusters and C15A clay particles dispersed in the protein matrix, and these were preferentially oriented in the extrusion direction only at 5 wt % of the C15 clay. The water vapor/oxygen barrier properties were improved with the presence of clay. Independent of the clay content used, the stiffness decreased and the extensibility increased in the presence of C15A due to the surfactant induced changes on the protein. The opposite "more expected" clay effect (increasing stiffness and decreasing extensibility) was observed for the MMT composites.

  • 50.
    Larsson, Karolina
    et al.
    RISE., Innventia.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Ankerfors, Mikael
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Polylactide latex/nanofibrillated cellulose bionanocomposites of high nanofibrillated cellulose content and nanopaper network structure prepared by a papermaking route2012Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, nr 3, s. 2460-2466Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous attempts to use polylactide (PLA) latex particles and nanofibrillated cellulose (NFC) in papermaking processing have been limited to low NFC content. In the present study, a bionanocomposite material was successfully produced using a PLA latex and NFC. The components were mixed using a wet mixing method and bionanocomposite films were made by filtration followed by hot pressing. In composite materials, the dispersion of the reinforcing component in the matrix is critical for the material properties. Biopolymers such as PLA are non-polar and soluble only in organic solvents; NFC is, however, highly hydrophilic. By utilizing latex, i.e., an aqueous dispersion of biopolymer micro-particles, wet mixing is possible and the problem of aggregation of the hydrophilic nanocellulose in organic solvent is avoided. The properties of the resulting NFC/PLA latex bionanocomposite films were analyzed. Thorough blending resulted in good dispersion of the reinforcing component within the matrix. Adding increasing amounts of NFC improved the Young's modulus, tensile strength, and strain at break of the bionanocomposite material. The increase in the tensile properties was linear with increasing NFC content as a result of the good dispersion. The NFC also improved the thermal stability of the bionanocomposite material.

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