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Bio-inspired polysaccharide nanocomposites and foams
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-4583-723X
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Today, the majority of materials used for single-use packaging are petroleum-based synthetic polymers. With increased concern about the environmental protection, efforts have been made to develop alternative biodegradable materials from renewable resources. Starch offers an attractive alternative since it is of low cost and abundant. However, the starch material is brittle without plasticizer and the mechanical properties of starch materials are highly sensitive to moisture.

In nature, the plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. This interesting combination of properties is attributed to a network based on cellulose microfibrils. Inspired by this, microfibrillated cellulose (MFC) reinforced starch-based nanocomposites films and foams were prepared. Films with a viscous matrix and MFC contents from 10 to 70wt% were successfully obtained by solvent casting. The films were characterized by DSC, DMA, FE-SEM, XRD, mercury density measurements, and dynamic water vapor sorption (DVS). At 70wt% MFC content a high tensile strength together with high modulus and high work of fracture was observed. This was due to the nanofiber and matrix properties, favourable nanofiber-matrix interaction, a good dispersion of nanofibers and the MFC network.

Novel nanocomposite foams were obtained by freeze-drying aquagels prepared from 8wt% solutions of amylopectin starch and MFC. The MFC content was varied from 10 to 70wt%. For composite foam with MFC contents up to 40wt%, improved mechanical properties were observed in compression. The mechanical properties depended both on the cell wall properties and the cell-structure of the foam. The effect of moisture (20-80% RH) on the dynamical properties of composite foam with 40wt% MFC was also investigated and compared to those of neat starch foam. Improved storage modulus was noted with MFC content, which was a result of the nanofiber network in the cell-wall. In addition, the moisture content decreased with MFC content, due to the less hydrophilic nature of MFC.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , 27 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2006:44
Keyword [en]
cellulose, starch, microfibrillated cellulose, biomimetic, nanocomposite, nanocomposite foam, mechanical properties
National Category
Biomaterials Science
Identifiers
URN: urn:nbn:se:kth:diva-4260OAI: oai:DiVA.org:kth-4260DiVA: diva2:11507
Presentation
2007-01-31, K1, teknikringen 56, KTH, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101118Available from: 2007-01-10 Created: 2007-01-10 Last updated: 2010-11-18Bibliographically approved
List of papers
1. Biomimetic polysaccharide nanocomposites of high cellulose content and high toughness
Open this publication in new window or tab >>Biomimetic polysaccharide nanocomposites of high cellulose content and high toughness
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 8, 2556-2563 p.Article in journal (Refereed) Published
Abstract [en]

Plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. Inspired by this, a nanostructured cellulose network is combined with an almost viscous polysaccharide matrix in the form of a 50/50 amylopectin-glycerol blend. Homogeneous films with a microfibrillated cellulose (MFC) nanofiber content in the range of 10-70 wt % are successfully cast. Characterization is carried out by dynamic mechanical analysis, field-emission scanning electron microscopy, X-ray diffraction, and mercury density measurements. The MFC is well dispersed and predominantly oriented random-in-the-plane. High tensile strength is combined with high modulus and very high work of fracture in the nanocomposite with 70 wt % WC. The reasons for this interesting combination of properties include nanofiber and matrix properties, favorable nanofiber-matrix interaction, good dispersion, and the ability of the MFC network to maintain its integrity to a strain of at least 8%.

Keyword
Biomimetics, Cellulose, Field emission microscopes, Polysaccharides, Scanning electron microscopy, Stiffness, Tensile strength, Toughness, X ray diffraction analysis
National Category
Biomaterials Science
Identifiers
urn:nbn:se:kth:diva-6717 (URN)10.1021/bm0703160 (DOI)000248755000029 ()17655354 (PubMedID)2-s2.0-34548253109 (Scopus ID)
Note
Uppdaterad från manuskript till artikel(20101118) Tidigare titel: Biomimetic polysaccharide nanocomposites of high cellulose content. QC 20101118Available from: 2007-01-10 Created: 2007-01-10 Last updated: 2017-12-14Bibliographically approved
2. Nanocomposite cellulose-starch foams prepared by lyophilization
Open this publication in new window or tab >>Nanocomposite cellulose-starch foams prepared by lyophilization
(English)Manuscript (Other academic)
National Category
Dentistry
Identifiers
urn:nbn:se:kth:diva-6718 (URN)
Note
QC 20101118Available from: 2007-01-10 Created: 2007-01-10 Last updated: 2010-11-18Bibliographically approved

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