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Publications (10 of 319) Show all publications
Nikjoo, R., Taylor, N., Edin, H., Hollertz, R., Wåhlander, M., Wågberg, L. & Malmström, E. (2017). Comparison of Oil-impregnated Papers with SiO2 and ZnO Nanoparticles or High Lignin Content, for the Effect of Superimposed Impulse Voltage on AC Surface PD. IEEE transactions on dielectrics and electrical insulation, 24(3), 1726-1734.
Open this publication in new window or tab >>Comparison of Oil-impregnated Papers with SiO2 and ZnO Nanoparticles or High Lignin Content, for the Effect of Superimposed Impulse Voltage on AC Surface PD
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2017 (English)In: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 24, no 3, 1726-1734 p.Article in journal (Refereed) Published
Abstract [en]

Surface discharge behavior of modified oil-impregnated paper (OIP) with nanoparticles (NPs), has been investigated under AC voltage with superimposed impulses. Surface Partial Discharges (PD) can develop at an oil-paper interface and lead to its degradation. Modified paper, made from fibers with adsorbed nanoparticles, can affect the partial discharge behavior of a paper in combination with oil at the interface between oil and fibers. Papers with two different concentrations (2 wt% and 6 wt%) of silica (SiO2), and paper with silanized zinc oxide (ZnO) nanoparticles (1 wt%) have been studied. Papers with SiO2 NPs showed lower impulse-induced surface PD activity. However, thorough purification during the production of SiO2 filled papers was necessary to achieve a good performance. With less purification, paper with 2 wt% of SiO2 did not show such significant improvements. Paper with 6 wt% of SiO2 NPs showed a large number of AC surface PDs, but low influence of impulse voltage on subsequent PD. Papers containing 1 wt% of silanized ZnO showed reduced relative permittivity, but no significant difference in surface PD behavior. The effect of high lignin content in Kraft paper has also been studied. Paper with higher lignin content showed better surface PD characteristics under the impulse. Paper with low concentrations of pure SiO2 NPs, and paper with high lignin content thus appear good candidates for further studies to improve the surface PD behavior of OIP.

Place, publisher, year, edition, pages
IEEE, 2017
Keyword
Nanoparticles, SiO2, silanized ZnO, superimposed impulse, oil-impregnated paper, lignin
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-211614 (URN)10.1109/TDEI.2017.006053 (DOI)000405000300046 ()2-s2.0-85022338626 (Scopus ID)
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy StorageSwedish Energy Agency
Note

QC 201708010

Available from: 2017-08-11 Created: 2017-08-11 Last updated: 2017-08-11Bibliographically approved
Chen, C., Illergård, J., Wågberg, L. & Ek, M. (2017). Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization. Paper presented at 14th European Workshop on Lignocellulosics and Pulp (EWLP), JUN, 2016, Autrans, FRANCE. Holzforschung, 71(7-8), 649-658.
Open this publication in new window or tab >>Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization
2017 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 7-8, 649-658 p.Article in journal (Refereed) Published
Abstract [en]

Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

Place, publisher, year, edition, pages
WALTER DE GRUYTER GMBH, 2017
Keyword
antibacterial, cellulosic fiber, fiber modification, layer by layer, nonleaching, polyelectrolyte
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-211388 (URN)10.1515/hf-2016-0184 (DOI)000404721500016 ()2-s2.0-85023188979 (Scopus ID)
Conference
14th European Workshop on Lignocellulosics and Pulp (EWLP), JUN, 2016, Autrans, FRANCE
Note

QC 20170808

Available from: 2017-08-08 Created: 2017-08-08 Last updated: 2017-08-08Bibliographically approved
Nordenström, M., Fall, A., Nyström, G. & Wågberg, L. (2017). Formation of Colloidal Nanocellulose Glasses and Gels. Langmuir, 33(38), 9772-9780.
Open this publication in new window or tab >>Formation of Colloidal Nanocellulose Glasses and Gels
2017 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 38, 9772-9780 p.Article in journal (Refereed) Published
Abstract [en]

Nanocellulose (NC) suspensions can form rigid volume-spanning arrested states (VASs) at very low volume fractions. The transition from a free-flowing dispersion to a VAS can be the result of either an increase in particle concentration or a reduction in interparticle repulsion. In this work, the concentration-induced transition has been studied with a special focus on the influence of the particle aspect ratio and surface charge density, and an attempt is made to classify these VASs. The results show that for these types of systems two general states can be identified: glasses and gels. These NC suspensions had threshold concentrations inversely proportional to the particle aspect ratio. This dependence indicates that the main reason for the transition is a mobility constraint that, together with the reversibility of the transition, classifies the VASs as colloidal glasses. If the interparticle repulsion is reduced, then the glasses can transform into gels. Thus, depending on the preparation route, either soft and reversible glasses or stiff and irreversible gels can be formed.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-215815 (URN)10.1021/acs.langmuir.7b01832 (DOI)000411918500030 ()28853581 (PubMedID)2-s2.0-85029917620 (Scopus ID)
Note

QC 20171017

Available from: 2017-10-17 Created: 2017-10-17 Last updated: 2017-10-17Bibliographically approved
Larsson, P. T., Karlsson, R.-M. P., Westlund, P.-O. & Wågberg, L. (2017). Internal Structure of Isolated Cellulose I Fibril Aggregates in the Water Swollen State. In: Agarwal, UP Atalla, RH Isogai, A (Ed.), Nanocelluloses: Their Preparation, Properties, and Applications. Paper presented at Anselme Payen Award Symposium in honor of Akira Isogai on Nanocelluloses, their Preparation, Properties and Applications / Spring ACS National Meeting, Mar 13-17, 2016, San Diego, CA (pp. 91-112). American Chemical Society (ACS), 1251.
Open this publication in new window or tab >>Internal Structure of Isolated Cellulose I Fibril Aggregates in the Water Swollen State
2017 (English)In: Nanocelluloses: Their Preparation, Properties, and Applications / [ed] Agarwal, UP Atalla, RH Isogai, A, American Chemical Society (ACS), 2017, Vol. 1251, 91-112 p.Conference paper (Refereed)
Abstract [en]

By combining H-2-NMRD and CP/MAS C-13-NMR measurements of water-based cellulose gels and of water swollen pulps it was possible to estimate the nature of the interior structure of cellulose fibril aggregates. A set of samples with high cellulose purity and low charge was used. The interpretation of data was based on a relaxation model describing the exchange dynamics for deuterium exchange between water molecules and cellulose hydroxyl groups. The theoretical model used made it possible to calculate cellulose surface-to-volume ratios (q-values) from both H-2-NMRD and CP/MAS C-13-NMR data. Good consistency between H-2-NMRD and CP/MAS C-13-NMR data was found. In all investigated samples the cellulose fibril aggregates showed a different degree of "openness" interpreted as the presence of interstitial water inside fibril aggregates. One result also showed that an increased degree of fibril aggregate openness results from the TEMPO-oxidation. Common to all samples was that in the water swollen state water molecules could access part of the fibril aggregate interior.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Series
ACS Symposium Series, ISSN 0097-6156 ; 1251
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-220871 (URN)000417770800005 ()978-0-8412-3218-1 (ISBN)
Conference
Anselme Payen Award Symposium in honor of Akira Isogai on Nanocelluloses, their Preparation, Properties and Applications / Spring ACS National Meeting, Mar 13-17, 2016, San Diego, CA
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

QC 20180108

Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-01-08Bibliographically approved
Ovaskainen, L., Olin, P., Tuominen, M., Pettersson, T. & Wågberg, L. (2017). The effect of different wear on superhydrophobic wax coatings. Nordic Pulp & Paper Research Journal, 32(2), 195-203.
Open this publication in new window or tab >>The effect of different wear on superhydrophobic wax coatings
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2017 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 2, 195-203 p.Article in journal (Refereed) Published
Abstract [en]

Wear resistance of superhydrophobic coatings made by spraying a crystallizing wax from supercritical carbon dioxide solutions was evaluated using several methods. Scratch tests were performed using a tip in contact with the surface using atomic force microscope (AFM). Compression tests were performed by applying different loads on a rubber stamp placed on the surface. Frictional wear was evaluated by stroking an index finger over the surfaces while measuring applied load and friction. The wetting properties of the coatings were subsequently evaluated as advancing and receding water contact angles, superhydrophobic sliding resistance according to a recently developed method and surface roughness, coating morphology was studied using scanning electron microscopy and optical profilometry. Scratching with tip of an AFM cantilever with a force of 12 nN removed major fraction of the wax coating from underlying silica substrate whereas subjecting the surfaces to a compressive load up to 59 kPa did not significantly influence the superhydrophobicity of the coatings. Frictional wear measurements indicate that superhydrophobic properties were immediately lost after pressing and moving a finger over the coating, as movement of the finger destroyed the fine surface structure. Nevertheless, the surfaces could withstand up to 200000 falling water drops without losing their superhydrophobicity.

Place, publisher, year, edition, pages
AB SVENSK PAPPERSTIDNING, 2017
Keyword
Superhydrophobicity, Superhydrophobic coating, Wear resistance, Friction test, Compression test, Drop impact resistance
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-211632 (URN)10.3183/NPPRJ-2017-32-02-p195-203 (DOI)000405197000005 ()
Funder
Swedish Foundation for Strategic Research , RMA08-0044
Note

QC 20180809

Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2017-08-09Bibliographically approved
Ghanadpour, M., Carosio, F. & Wågberg, L. (2017). Ultrastrong and flame-resistant freestanding films from nanocelluloses, self-assembled using a layer-by-layer approach. Applied Materials Today, 9, 229-239.
Open this publication in new window or tab >>Ultrastrong and flame-resistant freestanding films from nanocelluloses, self-assembled using a layer-by-layer approach
2017 (English)In: Applied Materials Today, ISSN 2352-9407, Vol. 9, 229-239 p.Article in journal (Refereed) Published
Abstract [en]

Nanosized cellulose nanofibrils (CNF) prepared from phosphorylated pulp fibers (P-CNF) are combined with CNF prepared from aminated fibers (cationic CNF) through a layer-by-layer (LbL) assembly to prepare a freestanding, transparent all-cellulose film. It is shown that the thermal stability and flame-retardant properties of the all CNF film are significantly improved when phosphorylated CNF is combined with cationic fibrils in an LbL assembled structure. The freestanding films also show a tensile strength of 160 MPa and a Young's modulus of 9 GPa, placing it among strongest freestanding LbL films fabricated so far, showing large promise for the use of these types of ultrathin films in advanced applications. The LbL build-up of the cationic CNF/P-CNF multilayer film is carefully studied by quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM). Hydrophobized silicon substrates are used for the LbL deposition and it is shown that the (cationic CNF/P-CNF)300 film, 2.3 μm thick, can be easily detached from the substrate using tweezers. The thermal stability, combustion behavior and mechanical properties of the films are further studied by thermogravimetric analysis, combustion and tensile tests respectively.

Place, publisher, year, edition, pages
Elsevier, 2017
Keyword
Cationic CNF, Flame-retardant, Freestanding film, Layer-by-layer assembly, Phosphorylated CNF
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-218617 (URN)10.1016/j.apmt.2017.08.002 (DOI)000417805400027 ()2-s2.0-85028597729 (Scopus ID)
Funder
Swedish Foundation for Strategic Research
Note

QC 20171130

Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-01-12Bibliographically approved
Malti, A., Edberg, J., Granberg, H., Khan, Z. U., Andreasen, J. W., Liu, X., . . . Berggren, M. (2016). An Organic Mixed Ion-Electron Conductor for Power Electronics. Advanced Science, 3(2), Article ID UNSP 1500305.
Open this publication in new window or tab >>An Organic Mixed Ion-Electron Conductor for Power Electronics
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2016 (English)In: Advanced Science, ISSN 2198-3844, Vol. 3, no 2, UNSP 1500305Article in journal (Refereed) Published
Abstract [en]

A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting nanopaper are exploited in devices which exhibit record values for the charge storage capacitance (1F) in supercapacitors and transconductance (1S) in electrochemical transistors.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016
Keyword
conducting polymer, nanofibrillated cellulose, PEDOT, supercapacitor, transconductance
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-183644 (URN)10.1002/advs.201500305 (DOI)000370336500011 ()2-s2.0-85003422153 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation, KAW 2011.0050Swedish Foundation for Strategic Research
Note

QC 20160319

Available from: 2016-03-19 Created: 2016-03-18 Last updated: 2017-01-10Bibliographically approved
Henschen, J., Illergård, J., Larsson, P. A., Ek, M. & Wågberg, L. (2016). Contact-active antibacterial aerogels from cellulose nanofibrils. Colloids and Surfaces B: Biointerfaces, 146, 415-422.
Open this publication in new window or tab >>Contact-active antibacterial aerogels from cellulose nanofibrils
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2016 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 146, 415-422 p.Article in journal (Refereed) Published
Abstract [en]

The use of cellulose aerogels as antibacterial materials has been investigated by applying a contact-active layer-by-layer modification to the aerogel surface. Studying the adsorption of multilayers of polyvinylamine (PVAm) and polyacrylic acid to aerogels comprising crosslinked cellulose nanofibrils and monitoring the subsequent bacterial adhesion revealed that up to 26 mg PVAm g aerogel−1 was adsorbed without noticeably affecting the aerogel structure. The antibacterial effect was tested by measuring the reduction of viable bacteria in solution when the aerogels were present. The results show that >99.9% of the bacteria adhered to the surface of the aerogels. Microscopy further showed adherence of bacteria to the surfaces of the modified aerogels. These results indicate that it is possible to create materials with three-dimensional cellulose structures that adsorb bacteria with very high efficiency utilizing the high specific surface area of the aerogels in combination with their open structure.

Keyword
Antibacterial, Cellulose nanofibrils, Aerogel, Contact active, Polymer adsorption
National Category
Paper, Pulp and Fiber Technology
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-185001 (URN)10.1016/j.colsurfb.2016.06.031 (DOI)000382269600046 ()2-s2.0-84977269377 (Scopus ID)
Funder
VINNOVA
Note

QC 20160825

Available from: 2016-04-07 Created: 2016-04-07 Last updated: 2017-11-30Bibliographically approved
Erlandsson, J., Duran, V. L., Granberg, H., Sandberg, M., Larsson, P. A. & Wågberg, L. (2016). Macro- and mesoporous nanocellulose beads for use in energy storage devices. APPLIED MATERIALS TODAY, 5, 246-254.
Open this publication in new window or tab >>Macro- and mesoporous nanocellulose beads for use in energy storage devices
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2016 (English)In: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 5, 246-254 p.Article in journal (Refereed) Published
Abstract [en]

Chemically cross-linked, wet-stable cellulose nanofibril (CNF) aerogel beads were fabricated using a novel procedure. The procedure facilitated controlled production of millimetre-sized CNF aerogel beads without freeze-drying or critical point drying, while still retaining a highly porous structure with low density. The aerogel beads were mechanically robust in the dry state, supporting loads of 1.3 N at 70% compression, even after being soaked in water and re-dried. Furthermore, they displayed both a good stability in water and a remarkably good shape recovery after wet compression. Owing to the stability in water, the entire surface of the highly porous aerogel beads could be successfully functionalized with polyelectrolytes and carboxyl-functionalized single-wall carbon nanotubes (CF-SWCNTs) using the Layer-by-Layer technique, introducing a significant electrical conductivity (1.6 mS/cm) to the aerogel beads. The functionalized, electrically conducting aerogel beads could carry as much as 2 kA/cm(2) and act as electrodes in a supercapacitor displaying a stabilized charge storage capacity of 9.8 F/g after 50 charging-discharging cycles.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
Supercapacitor, Layer-by-Layer, Size-reduced aerogel, Cellulose nanofibrils
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-202785 (URN)10.1016/j.apmt.2016.09.008 (DOI)000392950300023 ()2-s2.0-84995564002 (Scopus ID)
Note

QC 20170307

Available from: 2017-03-07 Created: 2017-03-07 Last updated: 2017-03-08Bibliographically approved
López Durán, V., Larsson, P. A. & Wågberg, L. (2016). On the relationship between fibre composition and material properties following periodate oxidation and borohydride reduction of lignocellulosic fibres. Cellulose (London), 23(6), 3495-3510.
Open this publication in new window or tab >>On the relationship between fibre composition and material properties following periodate oxidation and borohydride reduction of lignocellulosic fibres
2016 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 6, 3495-3510 p.Article in journal (Refereed) Published
Abstract [en]

Periodate oxidation followed by borohydride reduction was performed on four structurally different pulp fibres to clarify the effect of chemical composition on the structural and mechanical properties of sheets made from these fibres. The main purpose was to explore the possibility of extending the use of lignocellulose fibres in novel applications. The degree of oxidation, morphological changes, chemical and physical structure of the fibres, the supramolecular ordering of the cellulose and the mechanical performance of handsheets made from the fibres were studied. The results showed that both periodate oxidation and borohydride reduction are more reactive towards the carbohydrates of the fibres and as a result, there is an improvement in the tensile properties of the sheets. If the carbohydrates of the fibres are only periodate oxidised to produce dialdehydes, inter- and intra-fibre crosslinks can be formed, leading to paper with increase strength and higher stiffness. The borohydride reduction results in fibres and papers with a greater strength and ductility. It was also found that the characteristic ductility of these modified papers, emanating from the dialcohol cellulose produced, is limited with lignin-rich fibres.

Place, publisher, year, edition, pages
Springer Netherlands, 2016
Keyword
Borohydride reduction, Dialcohol cellulose, Dialdehyde cellulose, Lignocellulose fibres, Periodate oxidation, Strain-at-break, Tensile strength, Alcohols, Carbohydrates, Cellulose, Crosslinking, Ductility, Fibers, Lignin, Oxidation, Polyols, Borohydride reductions, Mechanical performance, Strain at break, Strength and ductilities, Structural and mechanical properties, Supramolecular ordering
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-194871 (URN)10.1007/s10570-016-1061-4 (DOI)000388961200009 ()2-s2.0-84984923972 (Scopus ID)
Funder
VINNOVA
Note

QC 20161213

Available from: 2016-12-13 Created: 2016-11-01 Last updated: 2017-11-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8622-0386

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