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Publications (10 of 281) Show all publications
Yang, X., Berthold, F. & Berglund, L. (2019). High-Density Molded Cellulose Fibers and Transparent Biocomposites Based on Oriented Holocellulose. ACS Applied Materials and Interfaces, 11(10), 10310-10319
Open this publication in new window or tab >>High-Density Molded Cellulose Fibers and Transparent Biocomposites Based on Oriented Holocellulose
2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 10, p. 10310-10319Article in journal (Refereed) Published
Abstract [en]

Ecofriendly materials based on well-preserved and nanostructured wood cellulose fibers are investigated for the purpose of load-bearing applications, where optical transmittance may be advantageous. Wood fibers are subjected to mild delignification, flow orientation, and hot-pressing to form an oriented material of low porosity. The biopolymer composition of the fibers is determined. Their morphology is studied by scanning electron microscopy, cellulose orientation is quantified by X-ray diffraction, and the effect of beating is investigated. Hot-pressed networks are impregnated by a methyl methacrylate monomer and polymerized to form thermoplastic wood fiber/poly(methyl methacrylate) biocomposites. Tensile tests are performed, as well as optical transmittance measurements. Structure-property relationships are discussed. High-density molded fibers from holocellulose have mechanical properties comparable with nanocellulose materials and are recyclable. The thermoplastic matrix biocomposites showed superior mechanical properties (Young's modulus of 20 GPa and ultimate strength of 310 MPa) at a fiber volume fraction of 52%, with high optical transmittance of 90%. The study presents a scalable approach for strong, stiff, and transparent molded fibers/biocomposites.Ecofriendly materials based on well-preserved and nanostructured wood cellulose fibers are investigated for the purpose of load-bearing applications, where optical transmittance may be advantageous. Wood fibers are subjected to mild delignification, flow orientation, and hot-pressing to form an oriented material of low porosity. The biopolymer composition of the fibers is determined. Their morphology is studied by scanning electron microscopy, cellulose orientation is quantified by X-ray diffraction, and the effect of beating is investigated. Hot-pressed networks are impregnated by a methyl methacrylate monomer and polymerized to form thermoplastic wood fiber/poly(methyl methacrylate) biocomposites. Tensile tests are performed, as well as optical transmittance measurements. Structure-property relationships are discussed. High-density molded fibers from holocellulose have mechanical properties comparable with nanocellulose materials and are recyclable. The thermoplastic matrix biocomposites showed superior mechanical properties (Young's modulus of 20 GPa and ultimate strength of 310 MPa) at a fiber volume fraction of 52%, with high optical transmittance of 90%. The study presents a scalable approach for strong, stiff, and transparent molded fibers/biocomposites.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
wood, nanocellulose, high strength, modulus, PMMA, interface
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-248343 (URN)10.1021/acsami.8b22134 (DOI)000461538000072 ()30762342 (PubMedID)
Note

QC 20190408

Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-04-08Bibliographically approved
Kaldéus, T., Träger, A., Berglund, L., Malmström, E. & Lo Re, G. (2019). Molecular engineering of cellulose-PCL bio-nanocomposite interface by reactive amphiphilic copolymer nanoparticles.
Open this publication in new window or tab >>Molecular engineering of cellulose-PCL bio-nanocomposite interface by reactive amphiphilic copolymer nanoparticles
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2019 (English)In: Article in journal (Refereed) Accepted
National Category
Polymer Technologies Paper, Pulp and Fiber Technology Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-244058 (URN)
Note

QC 20190218

Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-02-18Bibliographically approved
Medina, L., Ansari, F., Carosio, F., Salajkova, M. & Berglund, L. (2019). Nanocomposites from Clay, Cellulose Nanofibrils, and Epoxy with Improved Moisture Stability for Coatings and Semi-Structural Applications. ACS Applied Nano Materials
Open this publication in new window or tab >>Nanocomposites from Clay, Cellulose Nanofibrils, and Epoxy with Improved Moisture Stability for Coatings and Semi-Structural Applications
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2019 (English)In: ACS Applied Nano Materials, E-ISSN 2574-0970Article in journal (Refereed) Accepted
Abstract [en]

A new type of high reinforcement content clay-cellulose-thermoset nanocomposite was proposed, where epoxy precursors diffused into a wet porous clay-nanocellulose mat, followed by curing. The processing concept was scaled to > 200 µm thickness composites, the mechanical properties were high for nanocomposites and the materials showed better tensile properties at 90% RH compared with typical nanocellulose materials. The nanostructure and phase distributions were studied using transmission electron microscopy; Young’s modulus, yield strength, ultimate strength and ductility were determined as well as moisture sorption, fire retardancy and oxygen barrier properties. Clay and cellulose contents were varied, as well as the epoxy content. Epoxy had favorable effects on moisture stability, and also improved reinforcement effects at low reinforcement content. More homogeneous nano- and mesoscale epoxy distribution is still required for further property improvements. The materials constitute a new type of three-phase nanocomposites, of interest as coatings, films and as laminated composites for semi-structural applications.

Keywords
biocomposite, nanocellulose, mechanical, montmorillonite, fire
National Category
Composite Science and Engineering Paper, Pulp and Fiber Technology Nano Technology Materials Chemistry
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-249724 (URN)10.1021/acsanm.9b00459 (DOI)
Funder
Swedish Foundation for Strategic Research , RMA11-0065Knut and Alice Wallenberg Foundation
Available from: 2019-04-18 Created: 2019-04-18 Last updated: 2019-04-18
Boujemaoui, A., Ansari, F. & Berglund, L. (2019). Nanostructural Effects in High Cellulose Content Thermoplastic Nanocomposites with a Covalently Grafted Cellulose-Poly(methyl methacrylate) Interface. Paper presented at Symposium on Rational Design of Multifunctional Renewable-Resourced Materials held during the ACS National Meeting, AUG 19-23, 2018, Boston, MA. Biomacromolecules, 20(2), 598-607
Open this publication in new window or tab >>Nanostructural Effects in High Cellulose Content Thermoplastic Nanocomposites with a Covalently Grafted Cellulose-Poly(methyl methacrylate) Interface
2019 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 598-607Article in journal (Refereed) Published
Abstract [en]

A critical aspect in materials design of polymer nanocomposites is the nature of the nanoparticle/polymer interface. The present study investigates the effect of manipulation of the interface between cellulose nanofibrils (CNF) and poly(methyl methacrylate) (PMMA) on the optical, thermal, and mechanical properties of the corresponding nanocomposites. The CNF/PMMA interface is altered with a minimum of changes in material composition so that interface effects can be analyzed. The hydroxyl-rich surface of CNF fibrils is exploited to modify the CNF surface via an epoxide-hydroxyl reaction. CNF/PMMA nanocomposites are then prepared with high CNF content (similar to 38 wt %) using an approach where a porous CNF mat is impregnated with monomer or polymer. The nanocomposite interface is controlled by either providing PMMA grafts from the modified CNF surface or by solvent-assisted diffusion of PMMA into a CNF network (native and modified). The high content of CNF fibrils of similar to 6 nm diameter leads to a strong interface and polymer matrix distribution effects. Moisture uptake and mechanical properties are measured at different relative humidity conditions. The nanocomposites with PMMA molecules grafted to cellulose exhibited much higher optical transparency, thermal stability, and hygro-mechanical properties than the control samples. The present modification and preparation strategies are versatile and may be used for cellulose nanocomposites of other compositions, architectures, properties, and functionalities.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-245948 (URN)10.1021/acs.biomac.8b00701 (DOI)000458937200003 ()30047261 (PubMedID)2-s2.0-85050721988 (Scopus ID)
Conference
Symposium on Rational Design of Multifunctional Renewable-Resourced Materials held during the ACS National Meeting, AUG 19-23, 2018, Boston, MA
Note

QC 20190315

Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-03-15Bibliographically approved
Li, Y., Cheng, M., Jungstedt, E., Xu, B., Sun, L. & Berglund, L. (2019). Optically Transparent Wood Substrate for Perovskite Solar Cells. ACS Sustainable Chemistry and Engineering, 7(6), 6061-6067
Open this publication in new window or tab >>Optically Transparent Wood Substrate for Perovskite Solar Cells
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2019 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, no 6, p. 6061-6067Article in journal (Refereed) Published
Abstract [en]

Transparent wood is a candidate for use as an energy-saving building material due to its low density (ca. 1.2 g/cm(3)), high optical transmittance (over 85% at 1 mm thickness), low thermal conductivity (0.23 W m(-1) K-1), and good load-bearing performance with tough failure behavior (no shattering). High optical transmittance also makes transparent wood a candidate for optoelectronic devices. In this work, for the first time, perovskite solar cells processed at low temperature (<150 degrees C) were successfully assembled directly on transparent wood substrates. A power conversion efficiency up to 16.8% was obtained. The technologies demonstrated may pave the way for integration of solar cells with light transmitting wood building structures for energy-saving purposes.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Biocomposite, Perovskite solar cell, Energy-Efficient, Building material, Transparent wood, Mechanical properties
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-248333 (URN)10.1021/acssuschemeng.8b06248 (DOI)000461978200051 ()30918764 (PubMedID)2-s2.0-85063061391 (Scopus ID)
Note

QC 20190410

Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-04-10Bibliographically approved
Larsson, P. A., Riazanova, A., Ciftci, G. C., Rojas, R., Ovrebo, H. H., Wågberg, L. & Berglund, L. (2019). Towards optimised size distribution in commercial microfibrillated cellulose: a fractionation approach. Cellulose (London), 26(3), 1565-1575
Open this publication in new window or tab >>Towards optimised size distribution in commercial microfibrillated cellulose: a fractionation approach
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2019 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 3, p. 1565-1575Article in journal (Refereed) Published
Abstract [en]

For the successful commercialisation of microfibrillated cellulose (MFC) it is of utmost importance to carefully characterise the constituent cellulose particles. This could for instance lead to the development of MFC grades with size distributions tailored for specific applications. Characterization of MFC is challenging due to the heterogeneous chemical and structural nature of MFC. This study describes a fractionation approach that combines two steps of physical sieving of larger particles and a final centrifugation step to separate out the smallest, colloidally stable particles, resulting in four distinctly different size fractions. The properties, such as size and charge, of each fraction were studied, as well as MFC filtration time, film formation, and film properties (mechanical and optical). It was found that virtually all surface charges, determined by polyelectrolyte adsorption, are located in the colloidally stable fraction of the MFC. In addition, the amount of available surface charges can be used as an estimate of the degree of fibrillation of the MFC. The partly fibrillated particles frequently displayed a branching, fringed morphology. Mechanical testing of films from the different fractions revealed that the removal of large particles may be more important for strength than achieving full fibrillation. Overall, this study demonstrates that by controlling the size distribution in MFC grades, property profiles including dewatering time to make films by filtration, rheology, film strength and optical transmittance could be optimised. [GRAPHICS] .

Place, publisher, year, edition, pages
SPRINGER, 2019
Keywords
Cellulose nanofibrils, Cellulose films, Fractionation, Microfibrillated cellulose, Nanocellulose, Nanopaper
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-247842 (URN)10.1007/s10570-018-2214-4 (DOI)000460617900011 ()
Note

qc 20190326

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-03-26Bibliographically approved
Kupka, V., Zhou, Q., Ansari, F., Tang, H., Slouf, M., Vojtova, L., . . . Jancar, J. (2019). Well-dispersed polyurethane/cellulose nanocrystal nanocomposites synthesized by a solvent-free procedure in bulk. Polymer Composites, 40, E456-E465
Open this publication in new window or tab >>Well-dispersed polyurethane/cellulose nanocrystal nanocomposites synthesized by a solvent-free procedure in bulk
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2019 (English)In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 40, p. E456-E465Article in journal (Refereed) Published
Abstract [en]

Polyurethane (PU) nanocomposites utilizing cellulose nanocrystals (CNCs) as nanofiller and amorphous PU matrix were synthesized in a novel solvent-free bulk process. A green nanofiller, CNCs, was studied as reinforcement and was further modified by grafting poly(ethylene glycol) (PEG) on the CNC surface (CNC-PEG). Transmission electron microscopy revealed an excellent dispersion of the PEGylated CNC nanoparticles in the PU matrix, whereas as-received CNCs formed agglomerates. The results indicated strong improvements in tensile properties with Young's modulus increasing up to 50% and strength up to 25% for both, PU/CNC and PU/CNC-PEG nanocomposites. The enhanced tensile modulus was attributed to stiff particle reinforcement together with an increase in glass transition temperature.

Place, publisher, year, edition, pages
WILEY, 2019
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-246291 (URN)10.1002/pc.24748 (DOI)000459570800043 ()2-s2.0-85041194513 (Scopus ID)
Note

QC 20190325

Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2019-03-25Bibliographically approved
Berglund, L. & Burgert, I. (2018). Bioinspired Wood Nanotechnology for Functional Materials. Advanced Materials, 30(19), Article ID 1704285.
Open this publication in new window or tab >>Bioinspired Wood Nanotechnology for Functional Materials
2018 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 19, article id 1704285Article in journal (Refereed) Published
Abstract [en]

It is a challenging task to realize the vision of hierarchically structured nanomaterials for large-scale applications. Herein, the biomaterial wood as a large-scale biotemplate for functionalization at multiple scales is discussed, to provide an increased property range to this renewable and CO2-storing bioresource, which is available at low cost and in large quantities. The Progress Report reviews the emerging field of functional wood materials in view of the specific features of the structural template and novel nanotechnological approaches for the development of wood-polymer composites and wood-mineral hybrids for advanced property profiles and new functions.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
bioinspiration, functional materials, nanotechnology, structural hierarchy, wood
National Category
Polymer Chemistry Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-228261 (URN)10.1002/adma.201704285 (DOI)000431616700004 ()29468736 (PubMedID)2-s2.0-85042279348 (Scopus ID)
Note

QC 20180523

Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2018-05-23Bibliographically approved
Medina, L. & Berglund, L. (2018). Brick-and-mortar biocomposites from cellulose nanofibrils and clay nanoplatelets. Paper presented at 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA. Abstract of Papers of the American Chemical Society, 255
Open this publication in new window or tab >>Brick-and-mortar biocomposites from cellulose nanofibrils and clay nanoplatelets
2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-232280 (URN)000435539906237 ()
Conference
255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA
Note

QC 20180719

Available from: 2018-07-19 Created: 2018-07-19 Last updated: 2018-07-19Bibliographically approved
Koivurova, M., Vasileva, E., Li, Y., Berglund, L. & Popov, S. (2018). Complete spatial coherence characterization of quasi-random laser emission from dye doped transparent wood. Optics Express, 26(10), 13474-13482
Open this publication in new window or tab >>Complete spatial coherence characterization of quasi-random laser emission from dye doped transparent wood
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2018 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 10, p. 13474-13482Article in journal (Refereed) Published
Abstract [en]

We report on the experimental determination of the complete two coordinate spatial coherence function of light emitted by a quasi-random laser, implemented on recently introduced dye-doped transparent wood. The spatial coherence was measured by means of a double grating interferometer, which has some advantages over the standard Young's interferometer. Analysis of the spatial coherence reveals that emission from such a material can be considered as a superposition of several spatial modes produced by individual emitters within semi-ordered scattering medium. The overall degree of coherence, (gamma)over-bar, for this quasi-random laser was found to be 0.16 +/- 0.01, having possible applications in speckle free laser imaging and illumination.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2018
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-231223 (URN)10.1364/OE.26.013474 (DOI)000432457600117 ()29801372 (PubMedID)2-s2.0-85047074022 (Scopus ID)
Note

QC 20180628

Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2018-11-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5818-2378

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