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Wood cellulose biocomposites with fibrous structures at micro- and nanoscale
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.ORCID iD: 0000-0001-9832-027X
KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0001-5818-2378
2011 (English)In: Composites Science And Technology, ISSN 0266-3538, Vol. 71, no 3, 382-387 p.Article in journal (Refereed) Published
Abstract [en]

High-strength composites from wood fiber and nanofibrillated cellulose (NFC) were prepared in a semiautomatic sheet former. The composites were characterized by tensile tests, dynamic mechanical thermal analysis, field-emission scanning electron microscopy, and porosity measurements. The tensile strength increased from 98 MPa to 160 MPa and the work to fracture was more than doubled with the addition of 10% NFC to wood fibers. A hierarchical structure was obtained in the composites in the form of a micro-scale wood fiber network and an additional NFC nanofiber network linking wood fibers and also occupying some of the micro-scale porosity. Deformation mechanisms are discussed as well as possible applications of this biocomposites concept. (C) 2010 Published by Elsevier Ltd.

Place, publisher, year, edition, pages
2011. Vol. 71, no 3, 382-387 p.
Keyword [en]
Nanofibrillated cellulose (NFC), Fibers, Nano composites, Mechanical properties, Scanning electron microscopy (SEM)
National Category
Materials Engineering
URN: urn:nbn:se:kth:diva-31014DOI: 10.1016/j.compscitech.2010.12.007ISI: 000287288200016ScopusID: 2-s2.0-78751622635OAI: diva2:404812
QC 20110318Available from: 2011-03-18 Created: 2011-03-07 Last updated: 2011-04-06Bibliographically approved
In thesis
1. Nanofiber networks, aerogels and biocomposites based on nanofibrillated cellulose from wood
Open this publication in new window or tab >>Nanofiber networks, aerogels and biocomposites based on nanofibrillated cellulose from wood
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanofibrillated cellulose (NFC) from wood is an interesting material constituent of high strength and high aspect ratio, which easily forms networks through interfibril secondary bonding including hydrogen bonds. This has been exploited in preparation of new materials, which extend the range of properties for existing cellulosic materials. The objective is to explore processing-structure and structure-property relationships in NFC materials.

Dense networks of NFC, referred to as “nanopaper” having a random-in-the-plane orientation of the fibrils have been successfully prepared by a papermaking-like process involving vacuum filtration and water evaporation using laboratory papermaking equipment. Large, flat and transparent nanopaper sheets have thus been prepared in a relatively short time. Using the same preparation route, NFC was used to reinforce pulped wood fibers in dense network structures. NFC networks formed in the pore space of the wood fiber network give an interesting hierarchical structure of reduced porosity. These NFC/wood fiber biocomposites have greater strength, greater stiffness and greater strain-to-failure than reference networks of wood fibers only. In particular, the work to fracture (area under the stress-strain curve) is doubled with an NFC content of only 2%.

The papermaking preparation route was extended to prepare nanocomposites of high NFC content with a cellulose derivative matrix (hydroxyethyl cellulose, HEC) strongly associated to the NFC. Little HEC was lost during filtration. The NFC/HEC composites have high work to fracture, higher than that of any reported cellulose composite. This is related to NFC network characteristics, and HEC properties and its nanoscale distribution and association with NFC.

Higher porosity NFC nanopaper networks of high specific surface area were prepared by new routes including supercritical drying, tert-butanol freeze-drying and CO2 evaporation. Light-weight porous nanopaper materials resulted with mechanical properties similar to thermoplastics but with a much lower density and a specific surface area of up to 480 m2/g.

Freeze-drying of hydrocolloidal NFC dispersions was used to prepare ultra-high porosity foam structures. The NFC foams have a cellular foam structure of mixed open/closed cells and “nanopaper” cell wall. Control of density and mechanical properties was possible by variation of NFC concentration in the dispersion. A cellulose I foam of the highest porosity ever reported (99.5%) was prepared. The NFC foams have high ductility and toughness and may be of interest for applications involving mechanical energy absorption. Freeze-drying of NFC suspended in tert-butanol gave highly porous NFC network aerogels with a large surface area. The mechanical behavior was significantly different from NFC foams of similar density due to differences in deformation mechanisms for NFC nanofiber networks.


Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 74 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2011:024
Nanofibrillated cellulose, nanopaper, nanofiber, biocomposites, aerogel, foam
National Category
Materials Engineering
urn:nbn:se:kth:diva-32079 (URN)978-91-7415-931-8 (ISBN)
Public defence
2011-04-27, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
QC 20110406Available from: 2011-04-06 Created: 2011-04-05 Last updated: 2011-11-11Bibliographically approved

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