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  • 101.
    Miettinen, A.
    et al.
    University of Jyväskylä, Finland.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Kataja, M.
    University of Jyväskylä, Finland.
    Three-Dimensional Microstructural Properties of Nanofibrillated Cellulose Films2014Ingår i: International Journal of Molecular Sciences, ISSN 1661-6596, Vol. 4, nr 15, s. 6423-6440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanofibrillated cellulose (NFC) films have potential as oxygen barriers for, e.g., food packaging applications, but their use is limited by their hygroscopic characteristics. The three-dimensional microstructure of NFC films made of Pinus radiata (Radiata Pine) kraft pulp fibres has been assessed in this study, considering the structural development as a function of relative humidity (RH). The surface roughness, micro-porosity, thickness and their correlations were analyzed using X-ray microtomography (X-μCT) and computerized image analysis. The results are compared to those from scanning electron microscopy and laser profilometry. Based on a series of films having varying amounts of 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidated nanofibrils, it was demonstrated that X-μCT is suitable for assessing the surface and bulk 3D microstructure of the cellulose films. Additionally, one of the series was assessed at varying humidity levels, using the non-destructive capabilities of X-μCT and a newly developed humidity chamber for in-situ characterization. The oxygen transmission rate (OTR) of the films (20 g/m2) was below 3:7mLm-2 day-1 at humidity levels below 60% RH. However, the OTR increased considerably to 12:4mLm-2 day-1 when the humidity level increased to 80% RH. The increase in OTR was attributed to a change of the film porosity, which was reflected as an increase in local thickness. Hence, the characterization techniques applied in this study shed more light on the structures of NFC films and how they are affected by varying humidity levels. It was demonstrated that in increasing relative humidity the films swelled and the oxygen barrier properties decreased.

  • 102.
    Miettinen, Arttu
    et al.
    University of Jyvaskyla, Finland.
    Ekman, Axel
    University of Jyvaskyla, Finland.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Kataja, Markku
    University of Jyvaskyla, Finland.
    Measuring intrinsic thickness of rough membranes: application to nanofibrillated cellulose films2015Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 50, nr 21, s. 6926-6934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adequate measurement of thickness of sheet-like materials or membranes is most important for quantifying their properties such as density, barrier properties and mechanical strength. Depending on the surface roughness of the membrane, the thickness measured by standard micrometre devices (apparent thickness) may considerably overestimate the actual geometrical mean thickness (intrinsic thickness) required for such purposes. In this work, we present a method for correcting the measured apparent thickness value of thin membranes for their surface roughness, thereby obtaining an improved estimate of the intrinsic thickness. The surface roughness data required for the correction can be obtained by common surface profiling techniques. The method includes a calibration parameter, the value of which can be found experimentally by independent measurements, or can be estimated theoretically using results from standard mechanical contact theory. The method is tested on a set of nanofibrillated cellulose films with varying roughness levels controlled by pulp fibre content. The surface topography of film samples was measured using laser profilometry, and the method was calibrated experimentally using data from X-ray microtomographic images for one type of film. The intrinsic thickness estimates given by the new method are generally in good accordance with independent results obtained from X-ray microtomography.

  • 103. Mihranyan, A.
    et al.
    Esmaeili, M.
    Razaq, A.
    Alexeichik, D.
    Lindström, T.
    RISE, Innventia.
    Influence of the nanocellulose raw material characteristics on the electrochemical and mechanical properties of conductive paper electrodes2012Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, nr 10, s. 4463-4472Artikel i tidskrift (Refereegranskat)
  • 104. Mikczinski, M.
    et al.
    Josefsson, G.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Gamstedt, E.K.
    Fatikow, S.
    Introducing an in-situ microrobotic approach for assessing the stiffness properties of microfibrillated cellulose films2012Konferensbidrag (Refereegranskat)
  • 105.
    Mikczinski, M. R
    et al.
    OFFIS – Institute for Information Technology, Germany.
    Josefsson, G
    Uppsala University, Sweden.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Gamstedt, K
    Uppsala University, Sweden.
    Fatikow, S
    OFFIS – Institute for Information Technology, Germany.
    Nanorobotic Testing to Assess the Stiffness Properties of Nanopaper2014Ingår i: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, Vol. 30, nr 1, s. 115-119Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper deals with the nanorobotic and nondestructive assessment of the stiffness properties of nanopaper made of microfibrillated cellulose. Back-calculations of the Young's modulus show the agreement of the newly found results with conventional tensile testing results, therewith proving nanorobotics as a reasonable complement for conventional testing.

  • 106. Mikkonen, Kirsi S
    et al.
    Liljeström, Ville
    Serimaa, Riitva
    Berglund, Lars
    Salmen, Lennart
    RISE., Innventia.
    Tankanen, Maija
    Enzymatic tailoring reveals the effect of arabinoxylan structure on the properties of nanofibrillated cellulose-reinforced films2012Konferensbidrag (Refereegranskat)
  • 107. Mikkonen, K.S.
    et al.
    Pitkänen, L.
    Liljeström, V.
    Bergström E., Mabasa
    Serimaa, R.
    Salmen, L
    RISE, Innventia.
    Tenkanen, M.
    Arabinoxylan structure affects the reinforcement of films by microfibrillated cellulose2012Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, nr 2, s. 467-480Artikel i tidskrift (Refereegranskat)
  • 108. Mikkonen, K.S.
    et al.
    Stevanic, J.S.
    RISE, Innventia.
    Joly, C.
    Dole, P.
    Pirkkalainen, K.
    Serimaa, R.
    Salmen, L.
    RISE, Innventia.
    Tenkanen, M.
    Composite films from spruce galactoglucomannans with microfibrillated spruce wood cellulose2011Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, nr 3, s. 713-726Artikel i tidskrift (Refereegranskat)
  • 109. Mikkonen, K.S.
    et al.
    Stevanic Srndovic, Jasna
    RISE., Innventia.
    Pirkkalainen, K.
    Liljestrom, V.
    Serimaa, R.
    Salmen, Lennart
    RISE., Innventia.
    Tenkanen, M.
    Microfibrillated cellulose reinforced galactoglucomannan and arabinoxylan films2012Konferensbidrag (Refereegranskat)
  • 110.
    Mo, Lixin
    et al.
    Beijing Institute of Graphic Communication, China.
    Ran, Jun
    Beijing Zhongchao Banknote Designing and Plate-Making Co. Ltd, China.
    Yang, Li
    RISE., Innventia.
    Fang, Yi
    Beijing Institute of Graphic Communication, China.
    Zhai, Qingbin
    Beijing Institute of Graphic Communication, China.
    Li, Luhai
    Beijing Institute of Graphic Communication, China.
    Flexible transparent conductive films combining flexographic printed silver grids with CNT coating2016Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 27, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A high-performance ITO-free transparent conductive film (TCF) has been made by combining high resolution Ag grids with a carbon nanotube (CNT) coating. Ag grids printed with flexography have a 20 ÎŒm line width at a grid interval of 400 ÎŒm. The Ag grid/CNT hybrid film exhibits excellent overall performance, with a typical sheet resistance of 14.8 Ω/□ and 82.6% light transmittance at room temperature. This means a 23.98% reduction in sheet resistance and only 2.52% loss in transmittance compared to a pure Ag grid film. Analysis indicates that filling areas between the Ag grids and interconnecting the silver nanoparticles with the CNT coating are the primary reasons for the significantly improved conductivity of the hybrid film that also exhibits excellent flexibility and mechanical strength compared to an ITO film. The hybrid film may fully satisfy the requirements of different applications, e.g. use as the anode of polymer solar cells (PSCs). The J-V curve shows that the power conversion efficiency (PCE) of the PSCs using the Ag grid/CNT hybrid anode is 0.61%, which is 24.5% higher than that of the pure Ag grids with a PCE of 0.49%. Further investigations to improve the performance of the solar cells based on the printed hybrid TCFs are ongoing.

  • 111.
    Muneer, Faraz
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Andersson, Mariette
    SLU Swedish University of Agricultural Sciences, Sweden.
    Koch, Kristine
    SLU Swedish University of Agricultural Sciences, Sweden.
    Menzel, Carolin
    SLU Swedish University of Agricultural Sciences, Sweden.
    Hedenqvist, Mikael S.
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE., Innventia.
    Plivelic, Tomás S.
    Lund University, Sweden.
    Kuktaite, Ramune
    SLU Swedish University of Agricultural Sciences, Sweden.
    Nanostructural Morphology of Plasticized Wheat Gluten and Modified Potato Starch Composites: Relationship to Mechanical and Barrier Properties2015Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, nr 3, s. 695-705Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present study, we were able to produce composites of wheat gluten (WG) protein and a novel genetically modified potato starch (MPS) with attractive mechanical and gas barrier properties using extrusion. Characterization of the MPS revealed an altered chain length distribution of the amylopectin fraction and slightly increased amylose content compared to wild type potato starch. WG and MPS of different ratios plasticized with either glycerol or glycerol and water were extruded at 110 and 130 °C. The nanomorphology of the composites showed the MPS having semicrystalline structure of a characteristic lamellar arrangement with an approximately 100 Å period observed by small-angle X-ray scattering and a B-type crystal structure observed by wide-angle X-ray scattering analysis. WG has a structure resembling the hexagonal macromolecular arrangement as reported previously in WG films. A larger amount of β-sheets was observed in the samples 70/30 and 30/70 WG-MPS processed at 130 °C with 45% glycerol. Highly polymerized WG protein was found in the samples processed at 130 °C versus 110 °C. Also, greater amounts of WG protein in the blend resulted in greater extensibility (110 °C) and a decrease in both E-modulus and maximum stress at 110 and 130 °C, respectively. Under ambient conditions the WG-MPS composite (70/30) with 45% glycerol showed excellent gas barrier properties to be further explored in multilayer film packaging applications. (Graph presented).

  • 112.
    Naderi, A.
    et al.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Sundström, J.
    RISE, Innventia.
    Carboxymethylated nanofibrillated cellulose: Rheological studies2014Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 3, s. 1561-1571Artikel i tidskrift (Refereegranskat)
  • 113.
    Naderi, Ali
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia. BillerudKorsnäs, Sweden.
    Koschella, Andreas
    Friedrich Schiller University of Jena, Germany.
    Heinze, Thomas
    Friedrich Schiller University of Jena, Germany.
    Shih, Kuo-Chih
    University of Connecticut, USA; National Taiwan University, Taiwan.
    Nieh, Mu-Ping
    University of Connecticut, USA.
    Pfeifer, Annett
    Friedrich Schiller University of Jena, Germany.
    Chang, Chung-Chueh
    Stony Brook University, USA.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Sulfoethylated nanofibrillated cellulose: Production and properties2017Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 169, s. 515-523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 114.
    Naderi, Ali
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Lindström, Tom
    RISE - Research Institutes of Sweden, Bioekonomi. RISE., Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Effect of the size of the charged group on the properties of alkoxylated NFCs2017Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, nr 3, s. 1307-1317Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impact of the size of the charged group on the properties of alkoxylated NFC was studied by two chloroalkyl acid reagents. It was found that the employment of the larger 2-chloropropionic acid reagent leads to improved properties, e.g. higher fraction of nano-sized materials, and significantly better redispersion as compared to when the smaller monochloroacetic acid was employed. The differences in the impacts of the different reagents were hypothesized to be due to a more efficient disruption of the cohesion between the nanofibrils when a larger charged group was employed. 

  • 115.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    A comparative study of the rheological properties of three different nanofibrillated cellulose systems2016Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, nr 3, s. 354-363Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rheological properties of NFC systems in different conditions are of important for their handling and implementation in various industrial applications. In this investigation, the existence of wall-slip effects and the rheological characteristics of three different nano-fibrillated cellulose (NFC) systems - enzymatically pre-treated (NFCEnz), carboxymethyl cellulose grafted (NFCCMC) and carboxymethylated (NFCCarb) - were investigated. It was found that the rheological properties of NFCCarb are less affected by wall-slip effects when geometries with serrated surfaces are employed. The other systems showed, however, different degrees of susceptibility to these effects. The thixotropic properties of the different NFC systems, together with the impact of ambient ionic strength and temperature on the rheological properties of the systems, were also studied. It was found that the different systems displayed different rheological behaviours. In short, all systems regained most of their original properties as soon as severe shearing was ceased. The apparent viscosities of NFCEnz and NFCCMC were found to be little affected by the ionic strength of the system. However, the viscosity of the systems decreased somewhat with increasing temperatures. The viscosity of NFCCarb decreased on the other hand with the increasing ionic strength, but otherwise showed little sensitivity towards the ambient temperature. Hence, it was concluded that the rheological properties of NFCCarb were primarily governed by the electrosteric interactions between the NFC entities rather than the viscous properties of the liquid phase.

  • 116.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Carboxymethylated nanofibrillated cellulose: Effect of monovalent electrolytes on the rheological properties2014Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, s. 3507-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of the ionic strength on the properties of a carboxymethylated nanofibrillated cellulose (NFC) system was investigated through rheological studies. It was shown that homogenization of pulp suspensions containing a high amount of a monovalent electrolyte leads to the production of NFC systems displaying a lower magnitude in the rheological response as compared with systems prepared at lower ionic strengths conditions. It was further shown that increasing the ionic strength of NFC suspensions after their manufacturing also results in a lowering of the rheological response. The decreased rheological response in the former case was postulated to be caused by a lowering of the delamination deficiency of the homogenization process, due to decreased swelling of the carboxymethylated pulp, caused by the screening of the charges. In the latter case (post-addition of the electrolyte), the lowering of the rheological response was postulated to be due to the compression of the electrostatic double layer, when the electrostatic repulsion between the charged fibrils diminished in the presence of the electrolyte.

  • 117.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Erratum to: Nanofibrillated cellulose: properties reinvestigated2017Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, nr 12, s. 5713-5713Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the original publication of the article, the co-author name Tom Lindströ¶m was mistakenly missed out. Also the affiliation of the corresponding author was provided incorrectly. It has been updated in this erratum.

  • 118.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Rheological measurements on nanofibrillated cellulose systems: A science in progress2015Ingår i: Cellulose and Cellulose Derivatives: Synthesis, Modification and Applications / [ed] Mondal M.I.H., Nova Science Publishers, Inc., 2015, s. 187-204Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Nanofibrillated cellulose (NFC) systems are today on the height of the attention of the research community and the industry, thanks to their perceived potential in a sustainable society scenario. A related field that has seen an upsurge of interest is the rheology of NFC-based systems, as it is in the heart of the processing of these materials both in the manufacturing step and its industrial applications. However, despite considerable efforts the progress in the field has been sluggish. This is partly traced to, among others, the unsatisfactory disclosure of the experimental set-up in the published work (which hinders independent evaluations) and unawareness of the different characteristics of different NFC systems, which require careful set-up of the experiments. In this light, a few of the complicating aspects with regard to rheological studies of NFC-based systems are exemplified, and some of the more important features of the rheology of nanocellulosic systems with emphasis on single-component NFC systems are reviewed. The authors thereby hope to contribute to a better understanding of the already- published results, and inspire future contributors to address the earlier-mentioned inadequacies.

  • 119.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Rheological measurements on nanofibrillated cellulose systems: A science in progress2015Ingår i: Cellulose and cellulose derivatives, Nova Science , 2015, , s. 13Kapitel i bok, del av antologi (Refereegranskat)
  • 120.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Sundström, Jonas
    RISE., Innventia.
    Flodberg, Göran
    RISE., Innventia.
    A comparative study of the properties of three nano-fibrillated cellulose systems that have been produced at about the same energy consumption levels in the mechanical delamination step2016Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, nr 3, s. 364-371Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The viscosity, tensile strength- and barrier properties of enzymatically pre-treated- (NFCEnz), carboxymethylated- (NFCCarb) and carboxymethyl cellulose (CMC) modified (NFCCMC) nanofibrillated cellulose systems (NFC) that have been produced at about the same energy consumption levels in the mechanical delamination step in the manufacturing of the different NFCs are reported. It was found that NFCEnz and NFCCMC are characterized by low degrees of fibrillation. Carboxymethylated NFC displayed superior tensile strength properties, lower fiber fragment content and a higher viscosity when compared to NFCEnz and NFCCMC. Interestingly, NFCEnz displayed equal or better barrier properties compared to the highly fibrillated NFCCarb.

  • 121.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Sundström, Jonas
    RISE., Innventia.
    Repeated homogenization, a route for decreasing the energy consumption in the manufacturing process of carboxymethylated nanofibrillated cellulose?2015Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 2, s. 1147-1157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Energy-efficient manufacturing is a requirement for the large-scale production of nanofibrillated cellulose systems. Today, most strides involve the development of new physicochemical pre-treatment processes or invention of new or further-development of existing mechanical delamination processes; these approaches are often costly. In this communication, it was shown that significant reduction in energy consumption (~30–50 %) of the nanofibrillated cellulose (NFC) manufacturing process is possible by the wise employment of existing machinery and processes—without deterioration of the attractive properties of the NFC product. The suggested approach has further the additional advantage of increasing the yield of nanofibrillation, robustness of the manufacturing process, and increasing the out-put of the process. These notions can lead to significant energy savings in the NFC production. The novel manufacturing protocol involved repeated homogenization of the pulp suspension at low (~400 bar) applied homogenization pressures (as compared to those currently applied, ~1700 bar). It was hypothesized that this manufacturing protocol leads to a more homogeneous and effective shearing of the fibres, than is achievable by one time homogenization of the pulp slurry at high applied pressures. The investigations further showed that there exists an apparent yield of fibrillation (of about 40 %), above which the rheological properties of the NFC systems and the mechanical properties of the resulting NFC films remain unaffected. This observation [which is in accordance to published observations by e.g. Fall (2013)] can be employed to reduce the specific energy consumption in the NFC manufacturing process. Finally, the investigations also showed that the route that is used for dilution of concentrated NFC systems can significantly alter the properties of resulting NFC-films. It was postulated that a protocol based on the severe shearing of the NFC suspension (prior to NFC-film formation), e.g. by high pressure homogenization, can lead to a more homogeneous and better fibrillated system, which in turn might lead to the overestimation of the actual properties of the studied NFC system.

  • 122.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Sundström, Jonas
    RISE., Innventia.
    Flodberg, Göran
    RISE., Innventia.
    Can redispersible low-charged nanofibrillated cellulose be produced by the addition of carboxymethyl cellulose?2015Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 4, s. 568-577Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carboxymethyl cellulose (CMC) was added in various amounts (< 10% (w/w)) to a lowcharged (enzymatically pre-treated) NFC, and the suspensions were blended by either a low-shear propeller mixing- or high shear homogenization protocol. The suspensions were thereafter oven-dried, and redispersed using a high shear protocol. It was found that the mixing method has a profound effect on the apparent rheology of the never-dried systems. The addition of highly charged CMC-grades enabled, already at 1% (w/w) addition, the apparent dispersion of dried NFC. The rheological responses (viscosity and storage modulus) of the neverdried NFC-CMC systems were judged as conserved, when the rheological responses of the redispersed systems were compared with those of never-dried systems that had been produced by propeller mixing. The rheological responses of the redispersed systems were on the other hand found to be lower when compared to the rheological responses of the never-dried systems that had been produced by high shearing mixing. However, the mechanical- and barrier properties of the redispersed systems were found to be inferior to the never-dried equivalents - regardless of the mixing protocol.

  • 123.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Sundström, Jonas
    RISE., Innventia.
    Pettersson, Torbjörn
    KTH Royal Institute of Technology, Sweden.
    Flodberg, Göran
    RISE., Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Microfluidized carboxymethyl cellulose modified pulp: a nanofibrillated cellulose system with some attractive properties2015Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 2, s. 1159-1173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method (Ankerfors and Lindström in Method for providing nanocellulose comprising modified cellulose fibers, 2009) was employed to physically attach anionic carboxymethyl cellulose (CMC) chains onto wood pulp, upon which it was fibrillated by a microfluidizer-type homogenizer at high applied pressures and at dilute conditions [<3 % (w/w)]. It was found that the CMC-modified pulp can be fibrillated at the same consistencies as many of the commercially available NFC products. The NFC manufacturing process was also deemed to be energy efficient, as it lacked the need for mechanical pre-treatment, which is often a prerequisite for the production of many existing NFC systems. The CMC-based NFC was studied with respect to the rheological characteristics, and was also characterized using AFM-imaging. Further, The NFC was made into films, and its tensile strength was determined together with its barrier properties. In general, the rheological characteristics (viscosity and storage modulus) together with the tensile strength and oxygen barrier properties of the films were improved with increasing the number of passes through the microfluidizer. The fibrillated CMC-modified pulp was found to be as efficient as other NFC systems when employed as dry strength additive. The employment of the investigated material, which can be produced at acceptable costs and through environmentally benign and industrially relevant processes can, hence, potentially lead to significant future savings in the energy consumption levels in the paper and cardboard manufacturing processes, which have been recognized as major application areas of NFC products.

  • 124.
    Naderi, Ali
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Weise, Christoph F.
    NMRArc, Sweden.
    Flodberg, Göran
    RISE., Innventia.
    Sundström, Jonas
    RISE., Innventia.
    Junel, Kristina
    RISE., Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Runebjörk, Ann-Marie
    RISE., Innventia.
    Phosphorylated nanofibrillated cellulose: Production and properties2016Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, nr 1, s. 20-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phosphate functionalized nanofibrillated cellulose (NFC) was produced through an industrially attractive process, by reacting wood pulp with a phosphate containing salt, followed by mechanical delamination through microfluidization. The degrees of delamination of the phosphorylated NFCs (judged by among others AFM-imaging, rheological studies and tensile strength measurements on NFC films) were found to improve with increasing functionalization of the pulp and number of microfluidization-passes. The NFC systems were found to display similar characteristics as other well-known NFC systems. Interestingly, however, the sufficiently delaminated phosphorylated NFCs exhibited significantly lower oxygen permeability values (at RH 50%) than the published values of several well-known highly delaminated NFC systems. The potential application of the phosphorylated NFC in packaging applications can hence be envisaged.

  • 125.
    Nordli, H.R
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Rokstad, A.M
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Pukstad, B
    NTNU Norwegian University of Science and Technology, Norway; Trondheim University Hospital, Norway.
    Immunogenic properties of TEMPO-treated wood nanocellulose2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Bacterial nanocellulose (BNC) has been shown to be a good candidate in wound healing applications. However, there exists to date no cost efficient mass production of BNC. On the other side, wood nanocellulose (WNC) can be produced in large-scale and has also been suggested as a potential substrate for wound dressings. In WNC the cellulose fibers are disintegrated into individualized nanofibrils with typical diameters < 20 nm. Chemical pretreatment such as TEMPO-mediated oxidation yields a homogenous nanofibril morphology and modifies the surface chemistry of cellulose by introducing carboxyl groups and a small amount of aldehyde groups. A difference between BNC and WNC is that the last one usually consists of hemicellulose and small amounts of lignin, in addition to cellulose. Recently, we have demonstrated that WNC is not cytotoxic to 3T3-cells (mouse fibroblasts). However, to properly assess the properties of WNC for wound healing it is necessary to measure the cytotoxicity towards human skin cells, i.e. keratinocytes and fibroblasts, which is performed in this study. Additionally, using the lepirudin whole blood model the effect a material has on the activation of the complement system and the coagulation pathway can be studied. In order to use this model it is crucial to have a material which is free from bacterial composites, such as lipopolysaccharides (LPS). Importantly, we have in this work developed a new protocol for producing ultrapure nanocellulose with LPS concentration below 100 EU/g. This presentation will give an overview of recent results within the testing of the cytotoxic and immunogenic properties of WNC, which is important to verify for advanced wound healing applications.

  • 126. Olszewska, A.
    et al.
    Eronen, P.
    Johansson, L.-S.
    Malho, J.-M.
    Ankerfors, M.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Ruokolainen, J.
    Laine, J.
    Österberg, M.
    The behaviour of cationic NanoFibrillar Cellulose in aqueous media2011Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, nr 5, s. 1213-1226Artikel i tidskrift (Refereegranskat)
  • 127.
    Ottesen, V
    et al.
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering.
    Gregersen,  Ø
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering;.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Nanocellulose in Paper and Packaging2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    One possible way to improve competitiveness of paper materials is through utilization of nanocellulose to achieve new properties or to reduce production cost. Several studies have shown that nanofibrillar cellulose (NFC) can act as strength enhancing additive in paper or for paper surface improvements. NFC has the potential to bind large amounts of inorganic fillers in the paper sheet, and by this reduce energy consumption during paper production considerably. However, there are challenges that need to be addressed before the novel concepts can be realized, e.g. impaired drainage and drying of paper resulting from addition of NFC. This may be solved by obtaining the right balance between NFC quality, chemicals and additives. Promising results in this respect have been obtained  but this is still in an early stage. Fiber-based packaging materials represent a “green” alternative to petroleum based packaging solutions. Depending on the packaging category, different properties are important. For the segment liquid packaging board, barrier against oxygen is important. Currently, this is obtained by using aluminum, or the petroleum-based polymer EVOH in combination with a water barrier. Replacing these materials with “green” alternatives would represent a large environmental achievement. While superior oxygen barrier properties has been demonstrated for NFC,  good barrier against water and oxygen requires the combination of nanofibrils with complementary materials. Adequate combinations with other materials and feasible application techniques are still challenges that need to be solved. Other packaging segments require other properties, e.g. high stiffness or fracture toughness. By development of appropriate nanocellulose qualities, such properties can be improved. By preparing fibrils with small diameter, translucent films can be prepared. This is an interesting property for food packaging, where transparency may be a desired trait.

  • 128.
    Ottesen, V
    et al.
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering.
    Gregersen,  Ø
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering;.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Nanocellulose Properties of Interest for Paper and Packaging2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cellulose Nano-Fibrils (CNF) is a biocompatible nano-material with appealing mechanical and optical properties. The high specific surface area (SSA) of nanofibrils ensure that a large fraction of the polymer chains in each fibril are surface fibrils, meaning numerous surface hydroxyl groups will be available to form bonds between components in the paper, ensuring high density and strength. CNF may be added to conventional paper as a strengthening agent. CNF films may be used as a barrier coating, or CNF sheets may be used in a number of products due to their potential transparency, strength and barrier properties. As a paper additive, CNF as a nanomaterial acts as a material that increases density and form bonds between fibers in the paper, providing an increased strength and stiffness whereas dusting and permeability is reduced. For papers where strength is chiefly limited by inter-fiber bonding strength, increases in excess of 100 % may be achieved by addition of small amounts of CNF. Less, but still significant contributions can be seen for papers whose strength is less dependent on inter-fiber bonding strength. Due to the pore-blocking properties of CNF coupled with Cellulose’s hydrophilic properties, dewatering on the paper machine is a challenge when CNF is used in this fashion. The high density, viz. the low porosity and small pore size (~0.47 nm), of CNF films provide a significant reduction in mass-transport. Applying such a film to a less efficient barrier material, or producing a pure CNF film presents oxygen transfer rates comparable with the best synthetic polymer films produced for this purpose. Sheets of pure CNF or a CNF composite may transmit 90 % of incident light with a wavelength of 600 nm. This transparency is due to the high density and small fibril size in sheets of pure CNF or a CNF-based composite, which results in a lower scattering coefficient compared to corresponding conventional fiber based sheets. Transparent sheets such as these may be of interest in packaging applications where the packaged goods, such as foodstuffs or luxury articles, is desired displayed to the end customer. The properties of CNF, whether as a film, a paper additive or a major paper or composite component may be of significant industrial interest due to the unique properties of the material.

  • 129.
    Ottesen, Vegar
    et al.
    NTNU Norwegian university of science and technology, Norway.
    Roede, Erik Dobloug
    NTNU Norwegian university of science and technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioekonomi, PFI. NTNU Norwegian university of science and technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian university of science and technology, Norway.
    Focused ion beam tomography as a means for characterization of CNF in a paper matrix2017Ingår i: 16th Fundamental Research symposium, 2017, s. 595-609Konferensbidrag (Refereegranskat)
  • 130.
    Ottesen, Vegar
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind W.
    NTNU Norwegian University of Science and Technology, Norway.
    Mixing of cellulose nanofibrils and individual furnish components: Effects on paper properties and structure2016Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, nr 3, s. 441-447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermo-mechanical pulp (TMP) handsheets with different fractions of cellulose nano fibrils (CNF) and ground calcium carbonate (GCC) were made. CNF and retention chemicals were added in three different ways; to GCC, to long fibre fraction (LFF) or to complete furnish. The different addition strategies affected dewatering time, tensile strength and permeability, however opacity was not affected. Depending on filler and CNF levels, adding CNF to GCC produced the most beneficial effects on paper properties; CNF had a lower impact on dewatering times and permeability and GCC reduced strength less than for competing strategies. Adding CNF to LFF produced the least beneficial results using the same metrics. Scanning electron microscopy (SEM) analysis of the sheets reveal that sheets produced using the different strategies are structurally different; adding CNF and retention chemicals to GCC appears to have increased GCC clustering, whereas adding CNF and retention chemicals to LFF appears to have increased the fraction of GCC adsorbed on the fiber walls. CNF and retention chemical addition to complete furnish showed GCC clustering and adhering to the fiber walls, of which clustering appeared the most common.

  • 131. Penttilä, P.A.
    et al.
    Varnai, A.
    Pere, J.
    Tammelin, T.
    Salmen, L.
    RISE, Innventia.
    Siika-aho, M.
    Viikari, L.
    Serimaa, R.
    Xylan as limiting factor in enzymatic hydrolysis of nanocellulose2013Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, s. 135-141Artikel i tidskrift (Refereegranskat)
  • 132.
    Petroudy, S.R.D
    et al.
    NTNU Norwegian University of Science and Technology, Norway; Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, A
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, H
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Effects of bagasse microfibrillated cellulose and cationic polyacrylamide on key properties of bagasse paper2014Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 99, s. 311-318Artikel i tidskrift (Refereegranskat)
  • 133.
    Prakobna, Kasinee
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Medina, Lilian
    KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Mechanical performance and architecture of biocomposite honeycombs and foams from core-shell holocellulose nanofibers2016Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 88, s. 116-122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CNFs (cellulose nanofibers) based on holocellulose have a pure cellulose fibril core, with a hemicellulose coating. The diameter is only around 6-8 nm and the hemicellulose surface coating has anionic charge. These CNFs are used to prepare honeycomb and foam structures by freeze-drying from dilute hydrocolloidal suspensions. The materials are compared with materials based on "conventional" cellulose CNFs from sulfite pulp with respect to mechanical properties in compression. Characterization methods include FE-SEM of cellular structure, and the analysis includes comparisons with similar materials from other types of CNFs and data in the literature. The honeycomb structures show superior out-of-plane properties compared with the more isotropic foam structures, as expected. Honeycombs based on holocellulose CNFs showed better properties than sulfite pulp CNF honeycombs, since the cellular structure contained less defects. This is related to better stability of holocellulose CNFs in colloidal suspension.

  • 134. Pääkkö, M.
    et al.
    Vapaavuori, J.
    Silvennoinen, R.
    Kosonen, H.
    Ankerfors, Mikael
    RISE., STFI-Packforsk.
    Lindström, Tom
    RISE., STFI-Packforsk.
    Berglund, L. A.
    Ikkala, O.
    Long and entangled native cellulose i nanofibers allow flexible aerogels and hierarchically porous templates for functionalities2008Ingår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 4, nr 12, s. 2492-2499Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently it was shown that enzymatic and mechanical processing of macroscopic cellulose fibers lead to disintegration of long and entangled native cellulose I nanofibers in order to form mechanically strong aqueous gels (Pääkkö¶ et al., Biomacromolecules, 2007, 8, 1934). Here we demonstrate that (1) such aqueous nanofibrillar gels are unexpectedly robust to allow formation of highly porous aerogels by direct water removal by freeze-drying, (2) they are flexible, unlike most aerogels that suffer from brittleness, and (3) they allow flexible hierarchically porous templates for functionalities, e.g. for electrical conductivity. No crosslinking, solvent exchange nor supercritical drying are required to suppress the collapse during the aerogel preparation, unlike in typical aerogel preparations. The aerogels show a high porosity of ˜98% and a very low density of ca. 0.02 g cm -3. The flexibility of the aerogels manifests as a particularly high compressive strain of ca. 70%. In addition, the structure of the aerogels can be tuned from nanofibrillar to sheet-like skeletons with hierarchical micro- and nanoscale morphology and porosity by modifying the freeze-drying conditions. The porous flexible aerogel scaffold opens new possibilities for templating organic and inorganic matter for various functionalities. This is demonstrated here by dipping the aerogels in an electrically conducting polyaniline-surfactant solution which after rinsing off the unbound conducting polymer and drying leads to electrically conducting flexible aerogels with relatively high conductivity of around 1 ח 10-2 S cm-1. More generally, we foresee a wide variety of functional applications for highly porous flexible biomatter aerogels, such as for selective delivery/separation, tissue-engineering, nanocomposites upon impregnation by polymers, and other medical and pharmaceutical applications.

  • 135. Ragauskas, A. J.
    et al.
    Lindström, Tom
    RISE., Innventia, Material Processes.
    Nanocellulose and the future2014Ingår i: TAPPI Journal, ISSN 0734-1415, Vol. 13, nr 5, s. 5-6Artikel i tidskrift (Refereegranskat)
  • 136.
    Rees, A
    et al.
    Swansea University WCPC.
    Powell, L.C
    Centre for NanoHealth, College of Engineering, Swansea University, Swansea, UK.; Tissue Engineering and Reparative Dentistry, Cardiff University School of Dentistry, Cardiff, UK..
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Gethin, D.T
    Swansea University WCPC.
    Claypole, T.C
    Swansea University WCPC.
    Deganello, D
    Swansea University WCPC.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Studies on the 3D Printing of Nanocellulose Structures2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nanocellulose has a variety of advantages, which make the material most suitable for use in biomedical devices such as wound dressings. The material is strong, can be used for producing transparent films, can keep a moist environment and form elastic gels with bio-responsive characteristics. In this study we explore the application of nanocellulose as a bioink for use in a bioprinting process. Two different nanocelluloses were used, prepared with TEMPO mediated oxidation and a combination of carboxymethylation and periodate oxidation. The combination of carboxymethylation and periodate oxidation produced a homogeneous material with short nanofibrils. The small dimensions of the nanofibrils reduced the viscosity of the nanocellulose thus yielding a material with good rheological properties for use as a bioink. We also demonstrated that both nanocelluloses inhibited bacterial growth, which is an interesting property of these novel materials.

  • 137.
    Rees, Adam
    et al.
    Swansea University, UK.
    Powell, Lydia C.
    Swansea University, UK; Cardiff University, UK.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Gethin, David T.
    Swansea University, UK.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Hill, Katja E.
    Cardiff University, UK.
    Thomas, David W.
    Cardiff University, UK.
    3D bioprinting of carboxymethylated-periodate oxidized nanocellulose constructs for wound dressing applications2015Ingår i: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2015, artikel-id 925757Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanocellulose has a variety of advantages, which make the material most suitable for use in biomedical devices such as wound dressings. The material is strong, allows for production of transparent films, provides a moist wound healing environment, and can form elastic gels with bioresponsive characteristics. In this study, we explore the application of nanocellulose as a bioink for modifying film surfaces by a bioprinting process. Two different nanocelluloses were used, prepared with TEMPO mediated oxidation and a combination of carboxymethylation and periodate oxidation. The combination of carboxymethylation and periodate oxidation produced a homogeneous material with short nanofibrils, having widths <20 nm and lengths <200 nm. The small dimensions of the nanofibrils reduced the viscosity of the nanocellulose, thus yielding a material with good rheological properties for use as a bioink. The nanocellulose bioink was thus used for printing 3D porous structures, which is exemplified in this study. We also demonstrated that both nanocelluloses did not support bacterial growth, which is an interesting property of these novel materials.

  • 138. Rezayati Charani, P.
    et al.
    Dehghani-Firouzabadi, M.
    Afra, E.
    Blademo, Åsa
    RISE., Innventia.
    Naderi, Ali
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Production of microfibrillated cellulose from unbleached kraft pulp of Kenaf and Scotch Pine and its effect on the properties of hardwood kraft:: Microfibrillated cellulose paper2013Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, nr 5, s. 2559-2567Artikel i tidskrift (Refereegranskat)
  • 139. Rodionova, G.
    et al.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    TEMPO-oxidized cellulose nanofiber films:: effect of surface morphology on water resistance2012Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19Artikel i tidskrift (Refereegranskat)
  • 140. Rodionova, G.
    et al.
    Hoff, B.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Gas-phase esterification of microfibrillated cellulose (MFC) films2013Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20Artikel i tidskrift (Refereegranskat)
  • 141. Rodionova, G.
    et al.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Surface chemical modification of microfibrillated cellulose: improvement of barrier properties for packaging applications2011Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18Artikel i tidskrift (Refereegranskat)
  • 142. Rodionova, G.
    et al.
    Roudot, S.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Männle, F.
    Gregersen, Ø.
    The formation and characterisation of sustainable layered films incorporating microfibrillated cellulose (MFC)2012Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, s. 3690-3700Artikel i tidskrift (Refereegranskat)
  • 143.
    Rogstad Nordli, Henriette
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Rokstad, Anne Mari
    NTNU Norwegian University of Science and Technology, Norway.
    Pukstad, Brita
    NTNU Norwegian University of Science and Technology, Norway; Trondheim University Hospital, Norway.
    Producing ultrapure wood cellulose nanofibrils and evaluating the cytotoxicity using human skin cells2016Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 150, s. 65-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood cellulose nanofibrils (CNF) have been suggested as a potential wound healing material, but its utilization is limited by FDA requirements regarding endotoxin levels. In this study a method using sodium hydroxide followed by TEMPO mediated oxidation was developed to produce ultrapure cellulose nanofibrils, with an endotoxin level of 45 endotoxin units/g (EU/g) cellulose. Scanning transmission electron microscopy (S(T)EM) revealed a highly nanofibrillated structure (lateral width of 3.7 ± 1.3 nm). Assessment of cytotoxicity and metabolic activity on Normal Human Dermal Fibroblasts and Human Epidermal Keratinocytes was done. CNF-dispersion of 50 ÎŒg/ml did not affect the cells. CNF-aerogels induced a reduction of metabolic activity by the fibroblasts and keratinocytes, but no significant cell death. Cytokine profiling revealed no induction of the 27 cytokines tested upon exposure to CNF. The moisture-holding capacity of aerogels was relatively high (∌7500%), compared to a commercially available wound dressing (∌2500%), indicating that the CNF material is promising as dressing material for management of wounds with a moderate to high amount of exudate.

  • 144.
    Rättö, Peter
    et al.
    RISE., Innventia.
    Ålander, Eva
    RISE., Innventia.
    Water resistant NFC films2014Konferensbidrag (Refereegranskat)
  • 145.
    Röding, Magnus
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Biovetenskap och material, Jordbruk och livsmedel.
    Gaska, Karolina
    Chalmers University of Technology, Sweden .
    Kádár, Roland
    Chalmers University of Technology, Sweden.
    Loren, Niklas
    Chalmers University of Technology, Sweden.
    Computational Screening of Diffusive Transport in Nanoplatelet-Filled Composites: Use of Graphene To Enhance Polymer Barrier Properties2017Ingår i: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, nr 1, s. 160-167Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Motivated by the substantial interest in various fillers to enhance the barrier properties of polymeric films, especially graphene derivatives, we perform a computational screening of obstructed diffusion to explore the design parameter space of nanoplatelet-filled composites synthesized in silico. As a model for the nanoplatelets, we use circular and elliptical nonoverlapping and impermeable flat disks, and diffusion is stochastically simulated using a random-walk model, from which the effective diffusivity is calculated. On the basis of ∼1000 generated structures and diffusion simulations, we systematically investigate the impact of different nanoplatelet characteristics such as orientation, layering, size, polydispersity, shape, and amount. We conclude that the orientation, size, and amount of nanoplatelets are the most important parameters and show that using nanoplatelets oriented perpendicular to the diffusion direction, under reasonable assumptions, with approximately 0.2% (w/w) graphene, we can reach 90% reduction and, with approximately 1% (w/w) graphene, we can reach 99% reduction in diffusivity, purely because of geometrical effects, in a defect-free matrix with perfect compatibility. Additionally, our results suggest that the existing analytical models have some difficulty with extremely large aspect ratio (extremely flat) nanoplatelets, which calls for further development.

  • 146.
    Röding, Magnus
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut. University College London, Australia.
    Zagato, Elisa
    Ghent University, Belgium.
    Remaut, Katrien
    Ghent University, Belgium.
    Braeckmans, Kevin
    Ghent University, Belgium.
    Approximate Bayesian computation for estimating number concentrations of monodisperse nanoparticles in suspension by optical microscopy2016Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 93, nr 6, artikel-id 063311Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an approximate Bayesian computation scheme for estimating number concentrations of monodisperse diffusing nanoparticles in suspension by optical particle tracking microscopy. The method is based on the probability distribution of the time spent by a particle inside a detection region. We validate the method on suspensions of well-controlled reference particles. We illustrate its usefulness with an application in gene therapy, applying the method to estimate number concentrations of plasmid DNA molecules and the average number of DNA molecules complexed with liposomal drug delivery particles.

  • 147.
    Sani, Negar
    et al.
    Linköping University, Sweden.
    Wang, Xin
    RISE., Swedish ICT, Acreo.
    Granberg, Hjalmar
    RISE., Innventia.
    Andersson Ersman, Peter
    RISE., Swedish ICT, Acreo.
    Crispin, Xavier
    Linköping University, Sweden.
    Dyreklev, Peter
    RISE., Swedish ICT, Acreo.
    Engquist, Isak
    Linköping University, Sweden.
    Gustafsson, Göran
    RISE., Swedish ICT, Acreo.
    Berggren, Magnus
    Linköping University, Sweden.
    Flexible lamination-fabricated ultra-high frequency diodes based on self-supporting semiconducting composite film of silicon micro-particles and nano-fibrillated cellulose2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 28921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Low cost and flexible devices such as wearable electronics, e-labels and distributed sensors will make the future "internet of things" viable. To power and communicate with such systems, high frequency rectifiers are crucial components. We present a simple method to manufacture flexible diodes, operating at GHz frequencies, based on self-adhesive composite films of silicon micro-particles (Si-ÎŒPs) and glycerol dispersed in nanofibrillated cellulose (NFC). NFC, Si-ÎŒPs and glycerol are mixed in a water suspension, forming a self-supporting nanocellulose-silicon composite film after drying. This film is cut and laminated between a flexible pre-patterned Al bottom electrode and a conductive Ni-coated carbon tape top contact. A Schottky junction is established between the Al electrode and the Si-ÎŒPs. The resulting flexible diodes show current levels on the order of mA for an area of 2 mm2, a current rectification ratio up to 4 × 103 between 1 and 2 V bias and a cut-off frequency of 1.8 GHz. Energy harvesting experiments have been demonstrated using resistors as the load at 900 MHz and 1.8 GHz. The diode stack can be delaminated away from the Al electrode and then later on be transferred and reconfigured to another substrate. This provides us with reconfigurable GHz-operating diode circuits.

  • 148.
    Schachtl, M.
    et al.
    BASF SE, Germany.
    Erren, S.
    BASF SE, Germany.
    Scliönhaber, D.
    BASF SE, Germany.
    Dahlbom, P.
    Norske Skog Skogn, Norway.
    Steinsli, J. H.
    Norske Skog Skogn, Norway.
    Johansson, Lars
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Experiences with "dithionite Based Additives (DBA) in (C)TMP" in lab, pilot and mill scale: Synergies between high brightness, less specific energy consumption and development of pulp properties2016Ingår i: International Mechanical Pulping Conference 2016 (IMPC 2016), TAPPI Press, 2016, s. 59-69Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The purpose of this paper is to report about our experiences with treating softwood mechanical pulp (MP) with DBA directly injected into the gap of high consistency (HC) refiners used as chemical reactors to improve the competitiveness and the ecological footprint of (C)TMP based products. After the description of the main factors and pros and cons of conventional oxidative and reductive bleaching of sofhvood MP the basic principles of the treatment of MP with DBA in the (C)TMP refiner are outlined. By means of exemplary results of trials in lab, pilot and mill scale as well as of productions the main advantages of "DBA in (C)TMP" are illustrated: efficient brightness gain, reduction of anionic trash, high wood yield, reduction of hard chelating agents, saving of refining energy and increase of strength properties. Using the example of Norske Skog Skogn it is demonstrated how the system works in practice in the production of high bright and standard newsprint made from normal and lower quality wood. Finally it is pointed out that to a certain extent DBAs can be tailored to the needs of the respective mill.

  • 149. Siro, I.
    et al.
    Plackett, D.
    Hedenqvist, M.
    Ankerfors, M.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Highly transparent films from carboxymethylated microfibrillated cellulose: The effect of multiple homogenization steps on key properties2011Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, nr 5, s. 2652-2660Artikel i tidskrift (Refereegranskat)
  • 150.
    Sommertune, Jens
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Sugunan, Abhilash
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Ahniyaz, Anwar
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Stjernberg Bejhed, Rebecca
    Uppsala University, Sweden.
    Sarwe, Anna
    RISE., Swedish ICT, Acreo.
    Johansson, Christer
    RISE., Swedish ICT, Acreo.
    Balceris, Cristoph
    Technische Universität Braunschweig, Germany.
    Ludwig, Frank
    Technische Universität Braunschweig, Germany.
    Posth, Oliver
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Fornara, Andrea
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Polymer/iron oxide nanoparticle composites—A straight forward and scalable synthesis approach2015Ingår i: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 16, nr 8, s. 19752-19768Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy.

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