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Li, T., Song, J., Zhao, X., Yang, Z., Pastel, G., Xu, S., . . . Hu, L. (2018). Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose. Science Advances, 4(3), Article ID eaar3724.
Open this publication in new window or tab >>Anisotropic, lightweight, strong, and super thermally insulating nanowood with naturally aligned nanocellulose
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2018 (English)In: Science Advances, ISSN 0036-8156, E-ISSN 2375-2548, Vol. 4, no 3, article id eaar3724Article in journal (Refereed) Published
Abstract [en]

There has been a growing interest in thermal management materials due to the prevailing energy challenges and unfulfilled needs for thermal insulation applications. We demonstrate the exceptional thermal management capabilities of a large-scale, hierarchal alignment of cellulose nanofibrils directly fabricated fromwood, hereafter referred to as nanowood. Nanowood exhibits anisotropic thermal properties with an extremely low thermal conductivity of 0.03W/m·K in the transverse direction (perpendicular to the nanofibrils) and approximately two times higher thermal conductivity of 0.06W/m·K in the axial direction due to the hierarchically aligned nanofibrilswithin the highly porous backbone. The anisotropy of the thermal conductivity enables efficient thermal dissipation along the axial direction, thereby preventing local overheating on the illuminated side while yielding improved thermal insulation along the backside that cannot be obtained with isotropic thermal insulators. The nanowood also shows a low emissivity of <5% over the solar spectrum with the ability to effectively reflect solar thermal energy. Moreover, the nanowood is lightweight yet strong, owing to the effective bonding between the aligned cellulose nanofibrils with a high compressive strength of 13 MPa in the axial direction and 20MPa in the transverse direction at 75% strain, which exceeds other thermal insulation materials, such as silica and polymer aerogels, Styrofoam, and wool. The excellent thermal management, abundance, biodegradability, high mechanical strength, low mass density, and manufacturing scalability of the nanowood make this material highly attractive for practical thermal insulation applications. 

Place, publisher, year, edition, pages
American Association for the Advancement of Science, 2018
Keywords
Anisotropy, Biodegradability, Cellulose, Compressive strength, Insulation, Nanofibers, Silica, Solar energy, Strength of materials, Temperature control, Thermal conductivity, Thermal insulating materials, Thermal variables control, Cellulose nanofibrils, High mechanical strength, Insulation applications, Low thermal conductivity, Management capabilities, Solar thermal energy, Thermal insulation materials, Thermal management material, Thermal insulation
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-227394 (URN)10.1126/sciadv.aar3724 (DOI)000427892700039 ()2-s2.0-85044145510 (Scopus ID)
Note

Export Date: 9 May 2018; Article; Correspondence Address: Hu, L.; Department of Materials Science and Engineering, University of MarylandUnited States; email: binghu@umd.edu. QC 20180530

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-05-30Bibliographically approved
Karlsson, R.-M. P., Larsson, P. T., Yu, S., Pendergraph, S. A., Pettersson, T., Hellwig, J. & Wågberg, L. (2018). Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers. Journal of Colloid and Interface Science, 519, 119-129
Open this publication in new window or tab >>Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers
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2018 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 519, p. 119-129Article in journal (Refereed) Published
Abstract [en]

Macroscopic beads of water-based gels consisting of uncharged and partially charged beta-(1,4)-D-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling.

Place, publisher, year, edition, pages
Academic Press, 2018
Keywords
Swelling, Water uptake, Hydrogel, Cellulose, Small-angle X-ray scattering, Solid state NMR, Atomic force microscopy
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-226733 (URN)10.1016/j.jcis.2018.02.052 (DOI)000429633500013 ()29486431 (PubMedID)2-s2.0-85042413398 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20180503

Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-05-03Bibliographically approved
Ghanadpour, M., Carosio, F., Ruda, M. & Wågberg, L. (2018). Flame-retardant nanocomposite thin films based on phosphorylated cellulose nanofibrils: A study of flame-retardant mechanisms.
Open this publication in new window or tab >>Flame-retardant nanocomposite thin films based on phosphorylated cellulose nanofibrils: A study of flame-retardant mechanisms
2018 (English)In: Article in journal (Other (popular science, discussion, etc.)) Submitted
National Category
Chemical Sciences
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-224788 (URN)
Note

QC 20180323

Available from: 2018-03-23 Created: 2018-03-23 Last updated: 2018-05-24Bibliographically approved
Träger, A., Carlmark, A. & Wågberg, L. (2018). Interpenetrated Networks of Nanocellulose and Polyacrylamide with Excellent Mechanical and Absorptive Properties. Macromolecular materials and engineering (Print), 303(5), Article ID 1700594.
Open this publication in new window or tab >>Interpenetrated Networks of Nanocellulose and Polyacrylamide with Excellent Mechanical and Absorptive Properties
2018 (English)In: Macromolecular materials and engineering (Print), ISSN 1438-7492, E-ISSN 1439-2054, Vol. 303, no 5, article id 1700594Article in journal (Refereed) Published
Abstract [en]

Composites based on interpenetrating networks (IPNs) of cellulose nanofibril (CNF) aerogels and polyacrylamide are prepared and exhibit robust mechanical, water retaining, and re-swelling capacities. Furthermore, their swelling behavior is not affected by an increased ionic strength of the aqueous phase. These unprecedented IPNs combine the water retaining capacity of the polyacrylamide with the mechanical strength provided by the CNF aerogel template. The CNF aerogel/polyacrylamide composites exhibit a compressive stress at break greater than 250% compared with a neat polyacrylamide hydrogel. Furthermore, the composites retain their wet compression properties after drying and re-swelling, whereas the neat polyacrylamide hydrogels fail at a significantly lower stress and strain after drying and re-swelling. These composite materials highlight the potential of CNF aerogels to strengthen the mechanical properties and reduce the number of fracture defects during the drying and re-swelling of a hydrogel. These composites show the potential of being optimized for a plethora of applications, especially in the hygiene field and for biomedical devices.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
CNF aerogels, composites, hydrogels, polyacrylamide
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-228438 (URN)10.1002/mame.201700594 (DOI)000432026700007 ()2-s2.0-85046904921 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-05-31Bibliographically approved
Koklukaya, O., Carosio, F. & Wågberg, L. (2018). Tailoring flame-retardancy and strength of papers via layer-by-layer treatment of cellulose fibers. Cellulose (London), 25(4), 2691-2709
Open this publication in new window or tab >>Tailoring flame-retardancy and strength of papers via layer-by-layer treatment of cellulose fibers
2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 4, p. 2691-2709Article in journal (Refereed) Published
Abstract [en]

The layer-by-layer (LbL) technology was used to adsorb polyelectrolyte multilayers consisting of cationic polyethylenimine (PEI) and anionic sodium hexametaphosphate (SHMP) onto cellulose fibers in order to enhance the flame-retardancy and tensile strength of paper sheets made from these fibers. The fundamental effect of PEI molecular mass on the build-up of the multilayer film was investigated using model cellulose surfaces and a quartz crystal microbalance technique. The adsorption of a low (LMw) and a high molecular weight (HMw) PEI onto cellulose fibers and carboxymethylated (CM) cellulose fibers was investigated using polyelectrolyte titration. The fibers were consecutively treated with PEI and SHMP to deposit 3.5 bilayers (BL) on the fiber surfaces, and the treated fibers were then used to prepare sheets. In addition, a wet-strength paper sheet was prepared and treated with the same LbL coatings. Thermal gravimetric analysis of LbL-treated fibers showed that the onset temperature for cellulose degradation was lowered and that the amount of residue at 800 °C increased. A horizontal flame test and a vertical flame test were used to evaluate the combustion behavior of the paper sheets. Papers prepared from both cellulose fibers and CM-cellulose fibers treated with HMw-PEI/SHMP LbL-combination self-extinguished in a horizontal configuration despite the rather low amounts of adsorbed polymer which form very thin films (wet thickness of ca. 17 nm). The tensile properties of handsheets showed that 3.5 BL of HMw-PEI and SHMP increased the stress at break by 100% compared to sheets prepared from untreated cellulose fibers.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Chemical Sciences
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-225422 (URN)10.1007/s10570-018-1749-8 (DOI)000428925300039 ()2-s2.0-85044097243 (Scopus ID)
Note

QC 20180411

Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-19Bibliographically approved
Castro, D. O., Karim, Z., Medina, L., Häggström, J.-O. -., Carosio, F., Svedberg, A., . . . Berglund, L. A. (2018). The use of a pilot-scale continuous paper process for fire retardant cellulose-kaolinite nanocomposites. Composites Science And Technology, 162, 215-224
Open this publication in new window or tab >>The use of a pilot-scale continuous paper process for fire retardant cellulose-kaolinite nanocomposites
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2018 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, p. 215-224Article in journal (Refereed) Published
Abstract [en]

Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Biocomposite, Hybrid, Mechanical properties, Microfibrillated cellulose, Nanocellulose
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-228719 (URN)10.1016/j.compscitech.2018.04.032 (DOI)2-s2.0-85046634249 (Scopus ID)
Note

QC 20180530

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-05-30Bibliographically approved
Hollertz, R., López Durán, V., Larsson, P. A. & Wågberg, L. (2017). Chemically modified cellulose micro- and nanofibrils as paper-strength additives. Cellulose (London), 24(9), 3883-3899
Open this publication in new window or tab >>Chemically modified cellulose micro- and nanofibrils as paper-strength additives
2017 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 9, p. 3883-3899Article in journal (Refereed) Published
Abstract [en]

Chemically modified cellulose micro- and nanofibrils were successfully used as paper strength additives. Three different kinds of cellulose nanofibrils (CNFs) were studied: carboxymethylated CNFs, periodate-oxidised carboxymethylated CNFs and dopamine-grafted carboxymethylated CNFs, all prepared from bleached chemical fibres of dissolving grade, and one microfibrillated cellulose from unbleached kraft fibres. In addition to mechanical characterization of the final paper sheets the fibril retention, sheet density and sheet morphology were also studied as a function of addition of the four different cellulose fibrils. In general, the cellulose fibrils, when used as additives, significantly increased the tensile strength, Young’s modulus and strain-at-break of the paper sheets. The effects of the different fibrils on these properties were compared and evaluated and used to analyse the underlying mechanisms behind the strengthening effect. The strength-enhancing effect was most pronounced for the periodate-oxidised CNFs when they were added together with polyvinyl amine (PVAm) or poly(dimethyldiallylammonium chloride) (pDADMAC). The addition of periodate-oxidised CNFs, with pDADMAC as retention aid, resulted in a 37% increase in tensile strength at a 2 wt% addition and an 89% increase at a 15 wt% addition (from 67 to 92 and 125 kNm/kg, respectively) compared to a reference with only pDADMAC. Wet-strong sheets with a wet tensile index of 30 kNm/kg were also obtained when periodate-oxidised CNFs and PVAm were combined. This significant increase in wet strength is suggested to be the result of a formation of cross-links between the aldehyde groups, introduced by the periodate oxidation, and hydroxyl groups on the lignocellulosic fibres and the primary amines of PVAm. Even though less significant, there was also an increase in wet tensile strength when pDADMAC was used together with periodate-oxidised fibrils which shows that the aldehyde groups are able to increase the wet strength without the presence of the primary amines of the PVAm. As an alternative method to strengthen the fibre network, carboxymethylated CNFs grafted with dopamine, by an ethyl dimethylaminopropyl carbodiimide coupling, were used as a strength additive. When used as an additive, these CNFs showed a strong propensity to form films on and around the fibres and significantly increased the mechanical properties of the sheets. Their addition resulted in an increase in the Young´s modulus by 41%, from 5.1 to 7.2 GPa, and an increase in the tensile strength index of 98% (from 53 to 105 kNm/kg) with 5 wt% retained dopamine-grafted CNFs.

Place, publisher, year, edition, pages
Springer Netherlands, 2017
Keywords
Carboxymethylation, Cellulose nanofibrils, Dopamine grafting, Paper strength, Periodate oxidation, Strength additives, Additives, Aldehydes, Amines, Cellulose, Fibers, Grafting (chemical), Nanofibers, Neurophysiology, Oxidation, Paper products, Polyvinyl chlorides, Paper strengths, Tensile strength
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-218823 (URN)10.1007/s10570-017-1387-6 (DOI)2-s2.0-85021744663 (Scopus ID)
Note

QC 20180117

Available from: 2018-01-17 Created: 2018-01-17 Last updated: 2018-07-11Bibliographically approved
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, p. 1726-1734Article 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
Keywords
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, p. 649-658Article 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
Keywords
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, p. 9772-9780Article 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
Organisations
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8622-0386

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