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Strong and Moldable Cellulose Magnets with High Ferrite Nanoparticle Content
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. (WWSC)
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-0236-5420
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.ORCID iD: 0000-0003-2170-0076
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
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2014 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 22, 20524-20534 p.Article in journal (Refereed) Published
Abstract [en]

A major limitation in the development of highly functional hybrid nanocomposites is brittleness and low tensile strength at high inorganic nanoparticle content. Herein, cellulose nanofibers were extracted from wood and individually decorated with cobalt-ferrite nanoparticles and then for the first time molded at low temperature (<120 degrees C) into magnetic nanocomposites with up to 93 wt % inorganic content. The material structure was characterized by TEM and FE-SEM and mechanically tested as compression molded samples. The obtained porous magnetic sheets were further impregnated with a thermosetting epoxy resin, which improved the load-bearing functions of ferrite and cellulose material. A nanocomposite with 70 wt % ferrite, 20 wt % cellulose nanofibers, and 10 wt % epoxy showed a modulus of 12.6 GPa, a tensile strength of 97 MPa, and a strain at failure of ca. 4%. Magnetic characterization was performed in a vibrating sample magnetometer, which showed that the coercivity was unaffected and that the saturation magnetization was in proportion with the ferrite content. The used ferrite, CoFe2O4 is a magnetically hard material, demonstrated by that the composite material behaved as a traditional permanent magnet. The presented processing route is easily adaptable to prepare millimeter-thick and moldable magnetic objects. This suggests that the processing method has the potential to be scaled-up for industrial use for the preparation of a new subcategory of magnetic, low-cost, and moldable objects based on cellulose nanofibers.

Place, publisher, year, edition, pages
2014. Vol. 6, no 22, 20524-20534 p.
Keyword [en]
cellulose nanofiber, ferrite nanoparticle, nanocomposite, compression-molding, mechanical properties
National Category
Paper, Pulp and Fiber Technology
URN: urn:nbn:se:kth:diva-133567DOI: 10.1021/am506134kISI: 000345721400130PubMedID: 25331121ScopusID: 2-s2.0-84914674971OAI: diva2:662189
Knut and Alice Wallenberg Foundation

QC 20150116

Available from: 2013-11-06 Created: 2013-11-06 Last updated: 2015-01-16Bibliographically approved
In thesis
1. Compression-moulded and multifunctional cellulose network materials
Open this publication in new window or tab >>Compression-moulded and multifunctional cellulose network materials
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cellulose-based materials are widely used in a number of important applications (e.g. paper, wood, textiles). Additional developments are suggested by the growing interest for natural fibre-based composite and nanocomposite materials. The motivation is not only in the economic and ecological benefits, but is also related to advantageous properties and characteristics. The objective of this thesis is to provide a better understanding of process-structure-property relationships in some novel cellulose network materials with advanced functionalities, and showing potential large-scale processability. An important result is the favourable combination of mechanical properties observed for network-based cellulose materials.

Compression-moulding of cellulose pulp fibres under high pressure (45 MPa) and elevated temperature (120 – 180 oC) provides an environmentally friendly process for preparation of stiff and strong cellulose composite plates. The structure of these materials is characterized at multiple scales (molecular, supra-molecular and microscale). These observations are related to measured reduction in water retention ability and improvement in mechanical properties.

In a second part, cellulose nanofibrils (NFC) are functionalized with in-situ precipitated magnetic nanoparticles and formed into dense nanocomposite materials with high inorganic content. The precipitation conditions influence particle size distributions, which in turn affect the magnetic properties of the material. Besides, the decorated NFC network provides high stiffness, strength and toughness to materials with very high nanoparticle loading (up to 50 vol.%).

Subsequently, a method for impregnation of wet NFC network templates with a thermosetting epoxy resin is developed, enabling the preparation of well-dispersed epoxy-NFC nanocomposites with high ductility and moisture durable mechanical properties. Furthermore, cellulose fibrils interact positively with the epoxy during curing (covalent bond formation and accelerated curing). Potential large scale development of epoxy-NFC and magnetic nanocomposites is further demonstrated with the manufacturing of 3D shaped compression-moulded objects.

Finally, the wet impregnation route developed for epoxy is adapted to prepare UV-curable NFC nanocomposite films with a hyperbranched polymer matrix. Different chemical modifications are applied to the NFC in order to obtain moisture durable oxygen barrier properties.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 80 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2013:45
compression-moulding, cellulose fibre, nanocomposite, magnetic nanoparticle, epoxy, UV curing, oxygen barrier
National Category
Paper, Pulp and Fiber Technology
urn:nbn:se:kth:diva-133564 (URN)978-91-7501-911-6 (ISBN)
Public defence
2013-11-29, K1, Teknikringen 56, KTH, Stockholm, 10:00 (English)

QC 20131111

Available from: 2013-11-11 Created: 2013-11-06 Last updated: 2013-11-11Bibliographically approved

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Galland, SylvainAndersson, Richard L.Ström, ValterOlsson, RichardBerglund, Lars
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