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Publications (10 of 300) Show all publications
Peterson, A., Ostergren, I., Lotsari, A., Venkatesh, A., Thunberg, J., Strom, A., . . . Mueller, C. (2019). Dynamic Nanocellulose Networks for Thermoset-like yet Recyclable Plastics with a High Melt Stiffness and Creep Resistance. Biomacromolecules, 20(10), 3924-3932
Open this publication in new window or tab >>Dynamic Nanocellulose Networks for Thermoset-like yet Recyclable Plastics with a High Melt Stiffness and Creep Resistance
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2019 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 10, p. 3924-3932Article in journal (Refereed) Published
Abstract [en]

Many polymers, including polyethylene, feature a relatively low melting point and hence must be cross-linked to make them viable for applications that demand a high stiffness and creep resistance at elevated temperatures. The resulting thermoset plastics cannot be recycled, and therefore alternative materials with a reconfigurable internal network structure are in high demand. Here, we establish that such a thermoset-like yet recyclable material can be realized through the addition of a nanocellulose reinforcing agent. A network consisting of cellulose nanocrystals, nano- or microfibrils imparts many of the characteristics that are usually achieved through chemical cross-linking. For instance, the addition of only 7.5 wt % of either nanocellulose material significantly enhances the melt stiffness of an otherwise molten ethylene-acrylate copolymer by at least 1 order of magnitude. At the same time, the nanocellulose network reduces the melt creep elongation to less than 10%, whereas the neat molten matrix would rupture. At high shear rates, however, the molten composites do not display a significantly higher viscosity than the copolymer matrix, and therefore retain the processability of a thermoplastic material. Repeated re-extrusion at 140 degrees C does not compromise the thermomechanical properties, which indicates a high degree of recyclability. The versatility of dynamic nanocellulose networks is illustrated by 3D printing of a cellulose composite, where the high melt stiffness improves the printability of the resin.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-263355 (URN)10.1021/acs.biomac.9b00993 (DOI)000490658900030 ()31525970 (PubMedID)2-s2.0-85072966263 (Scopus ID)
Note

QC 20191119

Available from: 2019-11-19 Created: 2019-11-19 Last updated: 2019-11-19Bibliographically approved
Vasileva, E., Baitenov, A., Chen, H., Li, Y., Sychugov, I., Yan, M., . . . Popov, S. (2019). Effect of transparent wood on the polarization degree of light. Optics Letters, 44(12), 2962-2965
Open this publication in new window or tab >>Effect of transparent wood on the polarization degree of light
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2019 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, no 12, p. 2962-2965Article in journal (Refereed) Published
Abstract [en]

We report on the study of polarization properties of light propagating through transparent wood (TW), which is an anisotropically scattering medium, and consider two cases: completely polarized and totally unpolarized light. It was demonstrated that scattered light distribution is affected by the polarization state of incident light. Scattering is the most efficient for light polarized parallel to cellulose fibers. Furthermore, unpolarized light becomes partially polarized (with a polarization degree of 50%) after propagating through the TW. In the case of totally polarized incident light, however, the degree of polarization of transmitted light is decreased, in an extreme case to a few percent, and reveals an unusual angular dependence on the material orientation. The internal hierarchical complex structure of the material, in particular cellulose fibrils organized in lamellae, is believed to be responsible for the change of the light polarization degree. It was demonstrated that the depolarization properties are determined by the angle between the polarization of light and the wood fibers, emphasizing the impact of their internal structure, unique for different wood species.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-255191 (URN)10.1364/OL.44.002962 (DOI)000471636700005 ()31199356 (PubMedID)2-s2.0-85067943575 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-04Bibliographically approved
Koskela, S., Wang, S., Yang, X., Li, K., Srivastava, V., McKee, L. S., . . . Zhou, Q. (2019). Enzyme-assisted preparation of nanocellulose from wood holocellulose fibers. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. AMER CHEMICAL SOC, 257
Open this publication in new window or tab >>Enzyme-assisted preparation of nanocellulose from wood holocellulose fibers
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2019 (English)Other (Other academic)
Place, publisher, year, pages
AMER CHEMICAL SOC, 2019
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-257591 (URN)000478860502553 ()
Conference
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Note

QC 20190925

Available from: 2019-09-25 Created: 2019-09-25 Last updated: 2019-11-11Bibliographically approved
Chen, P., Terenzi, C., Furo, I., Berglund, L. & Wohlert, J. (2019). Heterogeneous dynamics in cellulose from molecular dynamics simulations. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. Abstracts of Papers of the American Chemical Society, 257
Open this publication in new window or tab >>Heterogeneous dynamics in cellulose from molecular dynamics simulations
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2019 (English)In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-257590 (URN)000478860502701 ()
Conference
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Note

QC 20190919

Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-10-15Bibliographically approved
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)2-s2.0-85062458848 (Scopus ID)
Note

QC 20190408

Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-10-23Bibliographically approved
Berglund, L., Yang, X. & Berthold, F. (2019). Holocellulose fibers: combining mechanical performance and optical transmittance. Paper presented at National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL. Abstracts of Papers of the American Chemical Society, 257
Open this publication in new window or tab >>Holocellulose fibers: combining mechanical performance and optical transmittance
2019 (English)In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-257612 (URN)000478860502411 ()
Conference
National Meeting of the American-Chemical-Society (ACS), MAR 31-APR 04, 2019, Orlando, FL
Note

QC 20190918

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-09-18Bibliographically approved
Koskela, S., Wang, S., Xu, D., Yang, X., Li, K., Berglund, L., . . . Zhou, Q. (2019). Lytic polysaccharide monooxygenase (LPMO) mediated production of ultra-fine cellulose nanofibres from delignified softwood fibres. Green Chemistry, 21(21), 5924-5933
Open this publication in new window or tab >>Lytic polysaccharide monooxygenase (LPMO) mediated production of ultra-fine cellulose nanofibres from delignified softwood fibres
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2019 (English)In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 21, no 21, p. 5924-5933Article in journal (Refereed) Published
Abstract [en]

The production of cellulose nanofibres (CNFs) typically requires harsh chemistry and strong mechanical fibrillation, both of which have negative environmental impacts. A possible solution is offered by lytic polysaccharide monooxygenases (LPMOs), oxidative enzymes that boost cellulose fibrillation. Although the role of LPMOs in oxidative modification of cellulosic substrates is rather well established, their use in the production of cellulose nanomaterials is not fully explored, and the effect of the carbohydrate-binding module (CBM) on nanofibrillation has not yet been reported. Herein, we studied the activity of two LPMOs, one of which was appended to a CBM, on delignified softwood fibres for green and energy-efficient production of CNFs. The CNFs were used to prepare cellulose nanopapers, and the structure and properties of both nanofibres and nanopapers were determined. Both enzymes were able to facilitate nanocellulose fibrillation and increase colloidal stability of the produced CNFs. However, the CBM-lacking LPMO was more efficient in introducing carboxyl groups (0.53 mmol/g) on the cellulose fibre surfaces and releasing CNFs with thinner width (4.3 ± 1.5 nm) from delignified spruce fibres than the modular LPMO (carboxylate content of 0.38 mmol/g and nanofibre width of 6.7± 2.5 nm through LPMO pretreatment followed by mild homogenisation. The prepared nanopapers showed improved mechanical properties (tensile strength of 262 MPa, and modulus of 16.2 GPa) compared to conventional CNFs preparation methods, demonstrating the potential of LPMOs as green alternatives for cellulose nanomaterials preparation.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
Keywords
nanocellulose LPMO CNF cellulose
National Category
Polymer Chemistry
Research subject
Biotechnology; Fibre and Polymer Science; Chemical Engineering; Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-260333 (URN)10.1039/C9GC02808K (DOI)000493077100014 ()2-s2.0-85074344957 (Scopus ID)
Note

QC 20191009

Available from: 2019-09-27 Created: 2019-09-27 Last updated: 2019-11-22Bibliographically 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
Kaldéus, T., Träger, A., Berglund, L., Malmström, E. & Lo Re, G. (2019). Molecular Engineering of the Cellulose-Poly(Caprolactone) Bio-Nanocomposite Interface by Reactive Amphiphilic Copolymer Nanoparticles. ACS NANO, 13(6), 6409-6420
Open this publication in new window or tab >>Molecular Engineering of the Cellulose-Poly(Caprolactone) Bio-Nanocomposite Interface by Reactive Amphiphilic Copolymer Nanoparticles
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2019 (English)In: ACS NANO, Vol. 13, no 6, p. 6409-6420Article in journal (Refereed) Published
Abstract [en]

A molecularly engineered water-borne reactive compatibilizer is designed for tuning of the interface in melt-processed thermoplastic poly(caprolactone) (PCL)-cellulose nanocomposites. The mechanical properties of the nanocomposites are studied by tensile testing and dynamic mechanical analysis. The reactive compatibilizer is a statistical copolymer of 2-(dimethylamino)ethyl methacrylate and 2-hydroxy methacrylate, which is subsequently esterified and quaternized. Quaternized ammonium groups in the reactive compatibilizer electrostatically match the negative surface charge of cellulose nanofibrils (CNFs). This results in core-shell CNFs with a thin uniform coating of the compatibilizer. This promotes the dispersion of CNFs in the PCL matrix, as concluded from high-resolution scanning electron microscopy and atomic force microscopy. Moreover, the compatibilizer "shell" has methacrylate functionalities, which allow for radical reactions during processing and links covalently with PCL. Compared to the bio-nanocomposite reference, the reactive compatibilizer (<4 wt %) increased Young's modulus by about 80% and work to fracture 10 times. Doubling the amount of peroxide caused further improved mechanical properties, in support of effects from higher cross-link density at the interface. Further studies of interfacial design in specific nanocellulose-based composite materials are warranted since the detrimental effects from CNFs agglomeration may have been underestimated.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
biocomposite, nanocellulose, reactive processing, mechanical properties, interphase, interface, biodegradable
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-255446 (URN)10.1021/acsnano.8b08257 (DOI)000473248300027 ()31083978 (PubMedID)2-s2.0-85066407552 (Scopus ID)
Note

QC 20190820

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-10-29Bibliographically approved
Andrieux, S., Medina, L., Herbst, M., Berglund, L. & Stubenrauch, C. (2019). Monodisperse highly ordered chitosan/cellulose nanocomposite foams. Composites. Part A, Applied science and manufacturing, 125, Article ID UNSP 105516.
Open this publication in new window or tab >>Monodisperse highly ordered chitosan/cellulose nanocomposite foams
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2019 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 125, article id UNSP 105516Article in journal (Refereed) Published
Abstract [en]

In solid foams, most physical properties are determined by the pore size and shape distributions and the organisation of the pores. For this reason, it is important to control the structure of porous materials. We recently tackled this issue with the help of microfluidic-aided foam templating, which allowed us to generate mono-disperse and highly ordered chitosan foams. However, the properties of foams also depend on the properties of the pore wall constituents. In case of chitosan-based foams, the foams have poor absolute mechanical properties, simply due to the fact that the solubility of chitosan in water is very low, so that the relative density of the freeze-dried foams becomes very small. Drawing inspiration from the field of nanocomposites, we incorporated cellulose nanofibres into the foamed chitosan solutions, with a view to strengthening the pore walls in the foam and thus the mechanical properties of the final foam. We report here how the cellulose nanofibres affect the structure of both the liquid foam template and the solid foam. The resulting nanocomposite foams have improved mechanical properties, which, however, are not proportional to the amount of cellulose nanofibres in the composites. One reason for this observation is the disturbance of the porous structure of the solid foams by the cellulose nanofibres.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Cellulose, Foams, Nanocomposites, Mechanical testing
National Category
Polymer Chemistry
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-261001 (URN)10.1016/j.compositesa.2019.105516 (DOI)000484878200005 ()2-s2.0-85068544162 (Scopus ID)
Note

QC 20191004

Available from: 2019-10-04 Created: 2019-10-04 Last updated: 2019-11-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5818-2378

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