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Publications (10 of 318) Show all publications
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: 2018-08-15Bibliographically approved
Tanpichai, S. & Oksman, K. (2018). Aligned-porous-structured poly(vinyl alcohol) foams with cellulose nanocrystals. In: AIP Conference Proceedings: . Paper presented at 2nd International Conference on Science and Technology of Emerging Materials 2018, STEMa 2018, Pattaya, Chonburi, Thailand, 18 July-20 July 2018. American Institute of Physics (AIP), 2010, Article ID 020007.
Open this publication in new window or tab >>Aligned-porous-structured poly(vinyl alcohol) foams with cellulose nanocrystals
2018 (English)In: AIP Conference Proceedings, American Institute of Physics (AIP), 2018, Vol. 2010, article id 020007Conference paper, Published paper (Refereed)
Abstract [en]

Poly(vinyl alcohol) (PVA) foams were prepared using a green lyophilization process without the use of foaming agents. PVA solutions with contents of CNCs (1 – 4 wt%) were prepared at two different freezing temperatures (−20 and −186 °C). With the addition of CNCs, moisture uptake of the CNC-PVA foams prepared at two freezing temperatures was lower than the neat PVA foams. With increasing CNC contents, no significant change of the moisture uptake could be observed for both types of the foams. Similar values of the moisture uptake could be found from both foams frozen at −20 and −186 °C. Scanning electron microscope measurements revealed the aligned-porous-structure of the foams frozen at −186 °C along with the ice growth direction while large and elongated pores were observed from the foams with the lower freezing temperature. These unique features of the foams prepared by a freeze-drying technique could be controlled by changing the freezing temperature, and these foams could be useful for specific applications such as tissue engineering scaffolds, thermal insulators or filters.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-72059 (URN)10.1063/1.5053183 (DOI)2-s2.0-85054337136 (Scopus ID)
Conference
2nd International Conference on Science and Technology of Emerging Materials 2018, STEMa 2018, Pattaya, Chonburi, Thailand, 18 July-20 July 2018
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
Kusano, Y., Madsen, B., Berglund, L., Aitomäki, Y. & Oksman, K. (2018). Dielectric barrier discharge plasma treatment of cellulose nanofibre surfaces. Surface Engineering, 34(11), 825-831
Open this publication in new window or tab >>Dielectric barrier discharge plasma treatment of cellulose nanofibre surfaces
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2018 (English)In: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 34, no 11, p. 825-831Article in journal (Refereed) Published
Abstract [en]

Dielectric barrier discharge plasma treatment was applied to modify cellulose nanofibre (CNF) surfaces with and without ultrasonic irradiation. The plasma treatment improved the wetting by deionised water and glycerol, and increased the contents of oxygen, carbonyl group, and carboxyl group on the nanofibre surface. Ultrasonic irradiation further enhanced the wetting and oxidation of the nanofibre coating. Scanning electron microscopic observations showed skeleton-like features on the plasma-treated surface, indicating preferential etching of weaker domains, such as low-molecular weight domains and amorphous phases. Ultrasonic irradiation also improved the uniformity of the treatment. Altogether, it is demonstrated that atmospheric pressure plasma treatment is a promising technique to modify the CNF surface before composite processing.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-63996 (URN)10.1080/02670844.2017.1334411 (DOI)000443914700004 ()2-s2.0-85020257445 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-10-08 (johcin)

Available from: 2017-06-14 Created: 2017-06-14 Last updated: 2018-10-08Bibliographically approved
Hassan, M., Berglund, L., Hassan, E., Abou-Zeid, R. & Oksman, K. (2018). Effect of xylanase pretreatment of rice straw unbleached soda and neutral sulfite pulps on isolation of nanofibers and their properties. Cellulose (London), 35(5), 2939-2953
Open this publication in new window or tab >>Effect of xylanase pretreatment of rice straw unbleached soda and neutral sulfite pulps on isolation of nanofibers and their properties
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2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 35, no 5, p. 2939-2953Article in journal (Refereed) Published
Abstract [en]

There is a recent interest in producing cellulose nanofibers with different surface properties from unbleached cellulose pulps for economic and environmental reasons. In the current study we investigated the use of xylanase pretreatment on two types of unbleached rice straw pulps, namely, soda and neutral sulfite, and their fibrillation to nanofibers using ultrafine grinding. The effect of xylanase pretreatment on the fibrillation progress, energy consumption, and nanofiber dimensions was studied. In addition, mechanical properties, water contact angle, water absorption, and roughness of produced nanopapers were studied. Although very thin nanofibers with a homogenous width could be isolated from both xylanase-treated and untreated pulps, the xylanase pretreatment resulted in faster fibrillation. In addition, nanopapers prepared from xylanase-treated nanofibers had better mechanical properties than those isolated from the untreated pulps. The energy consumption during fibrillation depended on the type of pulp; a slightly lower energy consumption (~ 8%) was recorded for xylanase-treated soda pulp while a higher energy consumption (~ 21%) was recorded for xylanase-treated neutral sulfite pulp compared to the untreated pulps.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Rice straw, Soda pulp, Neutral sulfite pulp, Cellulose nanofibers, Nanopaper
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-68331 (URN)10.1007/s10570-018-1779-2 (DOI)000431788000014 ()
Note

Validerad;2018;Nivå 2;2018-05-24 (andbra)

Available from: 2018-04-12 Created: 2018-04-12 Last updated: 2018-05-24Bibliographically approved
Salehpour, S., Rafieian, F., Jonoobi, M. & Oksman, K. (2018). Effects of molding temperature, pressure and time on polyvinyl alcohol nanocomposites properties produced by freeze drying technique. Industrial crops and products (Print), 121, 1-9
Open this publication in new window or tab >>Effects of molding temperature, pressure and time on polyvinyl alcohol nanocomposites properties produced by freeze drying technique
2018 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 121, p. 1-9Article in journal (Refereed) Published
Abstract [en]

The main aim of this study was to develop a novel approach to incorporate high cellulose nanofiber (CNF) loadings into polyvinyl alcohol (PVA) nanocomposites. The nanocomposites were prepared by freezing via liquid nitrogen and consequent freeze drying combined with hot press molding. To investigate the effect of the molding parameters on the morphological, mechanical and thermal properties, chemical structure and transparency of the PVA + CNF nanocomposites, two different mold pressures, temperatures and holding times were used for fabrication of PVA + CNF nanocomposites. The maximum tensile strength of 121 MPa of the PVA + CNF 20% nanocomposites was obtained when they were molded at 130 °C and 50 kPa for 7 min. Dynamic mechanical analysis showed that the storage modulus of the composites prepared at 130 °C and 50 kPa for 7 min is about 20% higher than nanocomposites molded at 150 °C and 150 kPa for 10 min. Optical properties (absorption spectra) of the PVA and PVA + CNF nanocomposites were increased as the mold pressures, temperature and holding time increased. Micrographs showed more sough fracture surface with increasing pressure and temperature during hot press molding.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-68590 (URN)10.1016/j.indcrop.2018.04.079 (DOI)000437996900001 ()2-s2.0-85046705277 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-02 (andbra)

Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2018-08-08Bibliographically 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 ()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: 2018-10-29Bibliographically approved
Mohammadi Amirabad, L., Jonoobi, M., Mousavi, N. S., Oksman, K., Kaboorani, A. & Yousefi, H. (2018). Improved antifungal activity and stability of chitosan nanofibers using cellulose nanocrystal on banknote papers. Carbohydrate Polymers, 189, 229-237
Open this publication in new window or tab >>Improved antifungal activity and stability of chitosan nanofibers using cellulose nanocrystal on banknote papers
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2018 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 189, p. 229-237Article in journal (Refereed) Published
Abstract [en]

Microorganisms can spread on the surface of banknotes and cause many infectious diseases. Chitosan nanofibers (CNFs) and cellulose nanocrystals (CNCs) are nanomaterials, which can affect the antimicrobial properties. In this study, the fungal species that grew on the surfaces of collected banknotes from different places were identified. To examine the antifungal effect of the both nanomaterials on the banknotes, the stable coatings using CNFs and CNCs emulsions were prepared by roller coating. The results revealed that the most colonies in the banknotes obtained from the bakeries and butcheries were Aspergillus sp., whereas the colonies in bus terminals and the hospitals were Aspergillus niger and Penicillium, respectively. The results showed that the CNCs had no antifungal effect alone on the aforementioned species, but it could improve the antifungal effect, adhesion, and stability of CNFs on the banknote surfaces. This study suggested a new approach to decrease the infection spreads through banknotes.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-67702 (URN)10.1016/j.carbpol.2018.02.041 (DOI)000428322000029 ()29580404 (PubMedID)2-s2.0-85042364621 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-02-26 (rokbeg)

Available from: 2018-02-20 Created: 2018-02-20 Last updated: 2018-06-11Bibliographically approved
Farid, T., Herrera Vargas, N. & Oksman, K. (2018). Investigation of crystalline structure of plasticized poly (lactic acid)/Banana nanofibers composites. Paper presented at 5th Global Conference on Polymer and Composite Materials (PCM 2018), Kitakyushu City, Japan, 10–13 April 2018. IOP Conference Series: Materials Science and Engineering, 369, Article ID 012031.
Open this publication in new window or tab >>Investigation of crystalline structure of plasticized poly (lactic acid)/Banana nanofibers composites
2018 (English)In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 369, article id 012031Article in journal (Refereed) Published
Abstract [en]

Polylactic acid (PLA) is a promising biodegradable candidate to replace synthetic commodity plastics in many applications. However, this polymer shows high brittleness, slow rate and lower degree of crystallization. The addition of plasticizing agents can enhance the toughness, but its effects on the crystallization behavior remain inconclusive. Therefore, this research is aiming to cast light on this area. Using differential scanning calorimetry (DSC) at a 2°C/min cooling rate, extruded neat PLA samples showed lower degree of crystallinity and thermal stability. This material shows cold crystallization upon heating and does recrystallize prior melting. These results indicate a clear instability in the crystalline state are confirmed by the crystallographic results by the X-ray diffractions (XRD) pattern and atomic force microscopic imagery. The addition of around 20 wt% of glycerol triacetate (GTA) with 1wt% of banana nanofibers (BNF) almost doubled the crystallinity. This modification is believed to occur through a dilution mechanism in order to increase crystallization rate yielding a more stable crystalline structure as shown by the XRD. However, the dynamic mechanical thermal analysis (DMTA) showed a 30 to 50% reduction in the room temperature storage modulus (stiffness) is in plasticized samples when compared to neat 100% PLA. Although these results shows the possibility to enhance the crystallization through a combination of plasticizing and nanoreinforcing effects, further studies is still needed to optimize the material formulation in order to find the best ratios to secure both a good crystallization and mechanical properties. This will definitively result in a new material that can be used for current and futuristic applications.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-69493 (URN)10.1088/1757-899X/369/1/012031 (DOI)000437169900031 ()2-s2.0-85049404993 (Scopus ID)
Conference
5th Global Conference on Polymer and Composite Materials (PCM 2018), Kitakyushu City, Japan, 10–13 April 2018
Note

Konferensartikel i tidskrift;2018-06-14 (andbra)

Available from: 2018-06-14 Created: 2018-06-14 Last updated: 2018-08-10Bibliographically approved
Hassan, M. L., Hassan, E. A., Fadel, S. M., Abou-zeid, R. E., Berglund, L. & Oksman, K. (2018). Metallo-Terpyridine-Modified Cellulose Nanofiber Membranes for Papermaking Wastewater Purification. Journal of Inorganic and Organometallic Polymers, 28(2), 439-447
Open this publication in new window or tab >>Metallo-Terpyridine-Modified Cellulose Nanofiber Membranes for Papermaking Wastewater Purification
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2018 (English)In: Journal of Inorganic and Organometallic Polymers, ISSN 1053-0495, E-ISSN 1572-8870, Vol. 28, no 2, p. 439-447Article in journal (Refereed) Published
Abstract [en]

Metallo-terpyridine compounds and polymers exhibit unique optical, electrical, magnetic and antimicrobial properties. Recently, metallo-terpyridine-modified cellulosic films with interesting porous structure, that exhibit these properties, have been prepared. Herein we report the use of Cu-terpyridine-modified oxidized cellulose nanofibers (OXCNF-Cu-Tpy) as membranes for treatment of effluents of paper mills to produce re-usable water. The OXCNF-Cu-Tpy was prepared by modification of TEMPO-oxidized CNF (OXCNF) using copper(II) complex of 4′-Chloro [2,2′:6′,2″] terpyridine. The modification was proven by elemental analysis and Fourier transform infrared spectroscopy. The prepared OXCNF-Cu-Tpy was also characterized using X-ray diffraction and transmission electron microscopy. The prepared membranes were evaluated regarding their microscopic structure using scanning electron microscopy, atomic force microscopy, contact angle measurement, water flux and rejection of sub-micron size suspended particles in papermaking wastewater effluent. Chemical modification of OXCNF with the Cu-Tpy groups significantly increased pure water flux of the membranes by about 52 and 194% depending on pressure used during filtration (0.5 and 1 MPa, respectively). Although both OXCNF and OXCNF-Cu-Tpy exhibited high efficiency in removing the sub-micron size suspended particles from wastewater effluent, OXCNF-Cu-Tpy membranes showed about 30% higher flux rate than OXCNF membranes.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-66732 (URN)10.1007/s10904-017-0685-7 (DOI)000426935500009 ()
Note

Validerad;2018;Nivå 1;2018-03-08 (andbra)

Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-09-27Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-4762-2854

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