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Publications (10 of 22) Show all publications
Wei, J., Geng, S., Hedlund, J. & Oksman, K. (2020). Lightweight, flexible, and multifunctional anisotropic nanocellulose-based aerogels for CO2 adsorption. Cellulose (London)
Open this publication in new window or tab >>Lightweight, flexible, and multifunctional anisotropic nanocellulose-based aerogels for CO2 adsorption
2020 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

CO2 adsorption is a promising strategy to reduce costs and energy use for CO2 separation. In this study, we developed CO2 adsorbents based on lightweight and flexible cellulose nanofiber aerogels with monolithic structures prepared via freeze-casting, and cellulose acetate or acetylated cellulose nanocrystals (a-CNCs) were introduced into the aerogels as functional materials using an impregnation method to provide CO2 affinity. The microstructure of the adsorbent was examined using scanning electron microscopy, and compression tests were performed to analyze the mechanical properties of the adsorbents. The CO2 adsorption behavior was studied by recording the adsorption isotherms and performing column breakthrough experiments. The samples showed excellent mechanical performance and had a CO2 adsorption capacity of up to 1.14 mmol/g at 101 kPa and 273 K. Compared to the adsorbent which contains cellulose acetate, the one impregnated with a-CNCs had better CO2 adsorption capacity and axial mechanical properties owing to the building of a nanoscale scaffold on the surface of the adsorbent. Although the CO2 adsorption capacity could be improved further, this paper reports a potential CO2 adsorbent that uses all cellulose-based materials, which is beneficial for the environment from both resource and function perspectives. Moreover, the interesting impregnation process provides a new method to attach functional materials to aerogels, which have potential for use in many other applications.

Place, publisher, year, edition, pages
Springer, 2020
Keywords
Cellulose aerogel, CO2 adsorption, Freeze-casting, Cellulose nanocrystals, Acetylation
National Category
Materials Engineering Chemical Process Engineering Bio Materials
Research subject
Chemical Technology; Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-77515 (URN)10.1007/s10570-019-02935-7 (DOI)
Funder
Bio4Energy
Available from: 2020-01-24 Created: 2020-01-24 Last updated: 2020-01-27
Geng, S., Wei, J., Jonasson, S., Hedlund, J. & Oksman, K. (2020). Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage. ACS Applied Materials and Interfaces
Open this publication in new window or tab >>Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage
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2020 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252Article in journal (Refereed) Epub ahead of print
Abstract [en]

In current times, CO2 capture and light-weight energy storage are receiving significant attention and will be vital functions in next-generation materials. Porous carbonaceous materials have great potential in these areas, whereas most of the developed carbon materials still have significant limitations, such as non-renewable resources, complex and costly processing or the absence of tailorable structure. In this study, a new strategy is developed for using the currently under-utilized lignin and cellulose nanofibers, which can be extracted from renewable resources to produce high-performance multifunctional carbon aerogels with a tailorable, anisotropic pore structure. Both the macro- and microstructure of the carbon aerogels can be simultaneously controlled by discreetly tuning the weight ratio of lignin to cellulose nanofibers in the carbon aerogel precursors, which considerably influences their final porosity and surface area. The designed carbon aerogels demonstrate excellent performance in both CO2 capture and capacitive energy storage, and the best results exhibit a CO2 adsorption capacity of 5.23 mmol g-1 at 273 K and 100 kPa, and a specific electrical double layer capacitance of 124 F g-1 at a current density of 0.2 A g-1, indicating that they have great future potential in the relevant applications.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
National Category
Materials Engineering Bio Materials Chemical Process Engineering
Research subject
Chemical Technology; Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-77516 (URN)10.1021/acsami.9b19955 (DOI)
Funder
Bio4EnergySwedish Research CouncilSwedish Research Council Formas
Available from: 2020-01-24 Created: 2020-01-24 Last updated: 2020-01-27
Wei, J., Geng, S., Pitkänen, O., Järvinen, T., Kordas, K. & Oksman, K. (2019). Biomass-derived electrospun carbon nanofiber networks for high-performance supercapacitors. In: : . Paper presented at The 22nd International Conference on Composite Materials (ICCM22).
Open this publication in new window or tab >>Biomass-derived electrospun carbon nanofiber networks for high-performance supercapacitors
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2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Keywords
Lignin, Carbon, Electrospinning, Supercapacitor, Nanofiber
National Category
Materials Engineering
Identifiers
urn:nbn:se:ltu:diva-76139 (URN)
Conference
The 22nd International Conference on Composite Materials (ICCM22)
Funder
Swedish Research Council, Carbon Lignin 2017-04240
Available from: 2019-09-27 Created: 2019-09-27 Last updated: 2019-10-22
PATEL, M., Schwendemann, D., Geng, S. & Oksman, K. (2019). Dispersion of chitin nanocrystals in polylactic acid nanocomposites prepared via liquid assisted extrusion by triethyl citrate. In: : . Paper presented at 6th EPNOE International Polysaccharide Conference.
Open this publication in new window or tab >>Dispersion of chitin nanocrystals in polylactic acid nanocomposites prepared via liquid assisted extrusion by triethyl citrate
2019 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Other Materials Engineering Composite Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-76971 (URN)
Conference
6th EPNOE International Polysaccharide Conference
Available from: 2019-11-29 Created: 2019-11-29 Last updated: 2019-11-29
Wei, J., Geng, S., Kumar, M., Pitkänen, O., Hietala, M. & Oksman, K. (2019). Investigation of Structure and Chemical Composition of Carbon Nanofibers Developed From Renewable Precursor. Frontiers in Materials, 6, Article ID 334.
Open this publication in new window or tab >>Investigation of Structure and Chemical Composition of Carbon Nanofibers Developed From Renewable Precursor
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2019 (English)In: Frontiers in Materials, E-ISSN 2296-8016, Vol. 6, article id 334Article in journal (Refereed) Published
Abstract [en]

In this study, lignin-based carbon nanofibers were prepared by electrospinning, followed by carbonization at four different temperatures (800, 1,000, 1,200, and 1,400°C). The surface and bulk elemental compositions were analyzed by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, respectively. In addition, the structure of the prepared carbon nanofibers was characterized by scanning electron microscopy, transmission electron microscopy, focused ion beam microscopy, and Raman spectroscopy. Results showed that all carbon nanofibers, irrespective of the carbonization temperature, had continuous and homogeneous structures. They were dense and no phase separation was observed. Moreover, the nanofibers carbonized at 800°C or 1,000°C predominately contained amorphous carbon and some non-carbon elements. When the carbonization was performed at a higher temperature (1,200°C or 1,400°C), non-carbon elements were effectively removed and nanocrystalline graphite was formed, indicating that high temperature carbonization facilitated the formation of ordered carbon structures.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2019
Keywords
lignin, electrospinning, carbon nanofibers, renewable resources, microstructure
National Category
Materials Engineering Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-77510 (URN)10.3389/fmats.2019.00334 (DOI)000505183400001 ()
Funder
Swedish Research Council, Carbon Lignin 2017-04240Bio4Energy
Note

Validerad;2020;Nivå 2;2020-01-27 (johcin)

Available from: 2020-01-24 Created: 2020-01-24 Last updated: 2020-01-27Bibliographically approved
Wei, J., Geng, S., Pitkänen, O., Järvinen, T., Kordas, K. & Oksman, K. (2019). Making good use of lignin – from a low-value biopolymer to energy storage devices. In: : . Paper presented at Nordic Polymer Days 2019.
Open this publication in new window or tab >>Making good use of lignin – from a low-value biopolymer to energy storage devices
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2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Materials Engineering
Identifiers
urn:nbn:se:ltu:diva-76140 (URN)
Conference
Nordic Polymer Days 2019
Funder
Swedish Research Council, Carbon Lignin 2017-04240
Available from: 2019-09-27 Created: 2019-09-27 Last updated: 2019-10-22
Wei, J., Geng, S., Sarmad, S., Hedlund, J. & Oksman, K. (2018). Adsorption of Carbon Dioxide on Cellulose Nanofiber-Based Monolithic Cryogels Impregnated with Acetylated Cellulose Nanocrystals. In: : . Paper presented at 72nd Forest Products Society (FPS) International Convention, Madison, Wisconsin, USA, June 11–14, 2018.
Open this publication in new window or tab >>Adsorption of Carbon Dioxide on Cellulose Nanofiber-Based Monolithic Cryogels Impregnated with Acetylated Cellulose Nanocrystals
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2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Nanocellulose materials with large surface area are prospective as substrates to obtain low-carbon-footprint CO2 adsorbents. In this study, ice-templating was conducted to prepare cellulose nanofibers (CNFs) based cryogels with monolithic structure, which can provide a good mass flow during the adsorption process. Furthermore, since acetyl groups have shown relatively high CO2 affinity, cellulose nanocrystals (CNCs) were acetylated and then impregnated into the cryogel to improve its CO2 capacity. Meanwhile, different amounts of cellulose acetate (CA) were impregnated and characterized as references. The success of the acetylation of CNCs was confirmed by Fourier-transform infrared spectroscopy (FTIR) and the degree of substitution was determined by titration. Results from the scanning electron microscopy (SEM) demonstrated that the monolithic structure was maintained after the impregnation. According to the breakthrough test, the cryogel impregnated with 0.1g of acetylated CNCs exhibits a much higher CO2 capacity with a value of 1.49 mmol/g compared to the CA impregnated ones. The mechanical properties of the cryogels were also evaluated by compression testing, revealing the outstanding reinforcing effect of acetylated CNCs.

Keywords
Nanocellulose, cryogel, adsorption, carbon dioxide, acetylation
National Category
Chemical Process Engineering Bio Materials
Research subject
Wood and Bionanocomposites; Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-71083 (URN)
Conference
72nd Forest Products Society (FPS) International Convention, Madison, Wisconsin, USA, June 11–14, 2018
Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2019-01-16Bibliographically approved
Singh, A. A., Geng, S., Herrera Vargas, N. & Oksman, K. (2018). Aligned plasticized polylactic acid cellulose nanocomposite tapes: Effect of drawing conditions. Composites. Part A, Applied science and manufacturing, 104, 101-107
Open this publication in new window or tab >>Aligned plasticized polylactic acid cellulose nanocomposite tapes: Effect of drawing conditions
2018 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 104, p. 101-107Article in journal (Refereed) Published
Abstract [en]

Aligned nanocomposite tapes based on plasticized polylactic acid (PLA) and 1 wt.% cellulose nanofibers (CNF) were prepared using uniaxial solid-state drawing, and the effects of drawing conditions including temperature, speed and draw ratio on the material were studied. Microscopy studies confirmed alignment and the formation of ‘shish-kebab’ morphology in the drawn tape. Mechanical properties demonstrate that the solid-state drawing is a very effective way to produce stronger and tougher PLA nanocomposites, and the toughness can be improved 60 times compared to the undrawn tape. Additionally, the thermal properties, i.e. storage modulus, glass transition temperature and degree of crystallinity were improved. These improvements are expected due to the synergistic effect of CNF in the nanocomposite and orientations induced by the solid-state drawing.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Nanocomposites, Mechanical properties, Thermal properties, Microstructural analysis
National Category
Composite Science and Engineering Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-64862 (URN)10.1016/j.compositesa.2017.10.019 (DOI)000418966900010 ()2-s2.0-85032722515 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-14 (andbra)

Available from: 2017-07-13 Created: 2017-07-13 Last updated: 2019-09-13Bibliographically approved
Geng, S. (2018). Cellulose-based Nanocomposites – The Relationship between Structure and Properties. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Cellulose-based Nanocomposites – The Relationship between Structure and Properties
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanocellulose materials extracted from various types of biomass have recently attracted significant attention. Due to their remarkable mechanical properties, large surface area and biodegradability, they can be promising reinforcements in nanocomposites. Cellulose-based nanocomposites constitutive of nanocellulose reinforcements and biodegradable polymer matrices have great potential to be used in environmentally friendly applications to replace fossil-based materials. However, the challenge of controlling their nanoscale structure, especially achieving good dispersion of nanocellulose in hydrophobic polymer matrices, still poses significant obstacles to producing high-performance nanocomposites. Therefore, this thesis reports several methods for structural modification of cellulose-based nanocomposites toward the objectives of improving the dispersion of nanocellulose and enhancing the properties of the nanocomposites. The methods include in situ emulsion polymerization in the presence of nanocellulose, crosslinking of polymer matrix, grafting of polymer brushes to nanocellulose and drawing of nanocomposites to obtain aligned structures. The resulting mechanical, thermal and other related properties are investigated, and the relationship between structure and properties of the nanocomposites are discussed.

To address the challenge of achieving good dispersion of nanocellulose in hydrophobic matrices, in situ emulsion polymerization of vinyl acetate monomer in the presence of cellulose nanocrystals has been developed. Microscopy results show that the in situ method improves the compatibility between nanocellulose and hydrophobic polymers, which consequently improves the dispersion of nanocellulose in the nanocomposites. Compared with direct mixed polymer/nanocellulose composites, the in situ synthesized nanocomposites exhibit higher stiffness and strength arising from their superior interphase volume, which is confirmed theoretically and experimentally. Crosslinking of partially hydrolyzed poly(vinyl acetate) by borate additives under different pH conditions has been studied to further enhance mechanical properties of the nanocomposites. Moreover, the “grafting to” modification method also helps to overcome this challenge. It is revealed that poly(ethylene glycol)-grafted cellulose nanofibers disperse better in poly(lactic acid) matrix than unmodified cellulose nanofibers, which is attributed to the improved compatibility and steric effect provided by the covalently grafted poly(ethylene glycol) brushes.

To substantially enhance the unidirectional mechanical properties of cellulose-based nanocomposites, a highly aligned structure in the materials is obtained through the drawing process. Drawing conditions including temperature, speed and draw ratio show considerable effects on the mechanical and thermal properties of the nanocomposites. Furthermore, the aligned nanocomposites consisting of poly(lactic acid) matrix and ultra-low weight fraction of poly(ethylene glycol)-grafted cellulose nanofibers demonstrate competitive strength, superb toughness and interesting optical behaviors compared with other aligned nanocellulose-based materials reported in the literature, indicating their potential to be further developed for large-scale environmentally friendly applications.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2018
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Nanocellulose, Nanocomposite, Dispersion, Poly(vinyl acetate), Poly(lactic acid), Alignment, Mechanical characteristics
National Category
Composite Science and Engineering Nano Technology Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-70411 (URN)978-91-7790-182-2 (ISBN)978-91-7790-183-9 (ISBN)
Public defence
2018-09-19, E632, Luleå, 10:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg FoundationBio4Energy
Available from: 2018-08-16 Created: 2018-08-15 Last updated: 2019-09-11Bibliographically approved
Geng, S., Yao, K., Zhou, Q. & Oksman, K. (2018). High-strength, High-toughness Aligned Polymer-based Nanocomposite Reinforced with Ultra-low Weight Fraction of Functionalized Nanocellulose. Biomacromolecules, 19(10), 4075-4083
Open this publication in new window or tab >>High-strength, High-toughness Aligned Polymer-based Nanocomposite Reinforced with Ultra-low Weight Fraction of Functionalized Nanocellulose
2018 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 10, p. 4075-4083Article in journal (Refereed) Published
Abstract [en]

Multifunctional lightweight, flexible, yet strong polymer-based nanocomposites are highly desired for specific applications. However, the control of orientation and dispersion of reinforcing nanoparticles and the optimization of the interfacial interaction still pose substantial challenges in nanocellulose-reinforced polymer composites. In this study, poly(ethylene glycol)-grafted nanocellulose fibers (TOCNF-g-PEG) has demonstrated much better dispersion in a poly(lactic acid) (PLA) matrix as compared to unmodified nanocellulose fibers. Through a uniaxial drawing method, aligned PLA/nanocellulose nanocomposites with high strength, high toughness, and unique optical behavior are obtained. With the incorporation of only 0.1 wt% of TOCNF-g-PEG in PLA, the ultimate strength of the nanocomposite reaches 343 MPa, which is significantly higher than that of other aligned PLA-based nanocomposites reported previously. Compared with the aligned nanocomposite reinforced with unmodified nanocellulose, the ultimate strength and toughness are enhanced by 39% and 70%, respectively. Moreover, the aligned nanocomposite film is highly transparent and possesses an anisotropic light scattering effect, revealing its significant potential for optical applications.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
nanocellulose, nanocomposite, alignment, mechanical characteristics, light scattering
National Category
Composite Science and Engineering Nano Technology Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-70591 (URN)10.1021/acs.biomac.8b01086 (DOI)000447118500018 ()30130395 (PubMedID)2-s2.0-85053301832 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationBio4Energy
Note

Validerad;2018;Nivå 2;2018-10-29 (johcin) 

Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2019-10-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1776-2725

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