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Biodegradable nanocomposite films based on amylopectin and chitosan
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The use of disposable material is rapidly increasing, today the absolute majority of the material used for these application, i.e. food packages, are oil-based plastics such as polyethylene and polypropylene. Therefore it is of great importance to find alternative biodegradable materials made from renewable resources for this huge growing market. In the present thesis, work and research to develop and improve such materials are presented. Amylopectin and chiotsan are two interesting material choises for these applications. In this thesis serveral ways of improving amylopectin (AP) and chitosan films are presented, using either Na+-montmorillonite (MMT) or microfibrillated cellulose (MFC). A novel approach of using a water-soluble coupling agent to enchance the strength and stiffness of MMT/AP-composites by increasing the adhesion beween the matrix and the filler. The results from IR, mechanical and moisture absorption tests show that the coupling agent indeed improve the properties of the composite films. Studies on MFC/AP show that the MFC have a remarkable effect of acting as a reinforcing plasticiser creating a flexible material without the use of a plasticiser. Thermal measurements show that the MFC have a ability to bound water very tightly. This was further investigated with thermal analysis. Chitosan, another interesting “green material”, and the effect of using MFC and/or a well-known buffer treatment, to enhace the mechanical properties of chitosan films in dry and wet conditions have here been investigated. The addition of MFC prevented extensive shrinkage in the wet condition due to increased wet stiffness.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , 41 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2006:36
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-4168ISBN: 91-7178-477-2 (print)OAI: oai:DiVA.org:kth-4168DiVA: diva2:11027
Presentation
2006-11-22, V3, Väg&Vatten, Teknikringen 72, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20101122Available from: 2006-11-13 Created: 2006-11-13 Last updated: 2010-11-22Bibliographically approved
List of papers
1. Enhanced film forming and film properties of amylopectin using micro-fibrillated cellulose
Open this publication in new window or tab >>Enhanced film forming and film properties of amylopectin using micro-fibrillated cellulose
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2007 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 68, no 4, 718-727 p.Article in journal (Refereed) Published
Abstract [en]

This work describes a novel approach to produce amylopectin films with enhanced properties by the addition of micro fibrillated cellulose (MFC). Aqueous dispersions of gelatinized amylopectin, glycerol (0-38 wt%) and MFC (0-10 wt%) were cast at ambient temperature and 50% relative humidity and, after 10 days of storage, the tensile properties were investigated. The structure of the composite films was revealed by optical, atomic force and transmission electron microscopy. The moisture content was determined by thermogravimetry and the temperature-dependent film rigidity was measured by thermal mechanical analysis. Synchrotron simultaneous small- and wide-angle X-ray measurements revealed that the solutions had to be heated to above 85 degrees C in order to achieve complete gelatinization. Optical microscopy and atomic force microscopy revealed uniformly distributed MFC aggregates in the films, with a length of 10-90 mu m and a width spanning from a few hundred nanometers to several microns. Transmission electron microscopy showed that, in addition to aggregates, single MFC microfibrils were also embedded in the amylopectin matrix. It was impossible to cast antylopectin films of sufficient quality with less than 38 wt% glycerol. However, when MFC was added it was possible to produce high quality films even without glycerol. The film without glycerol was stiff and strong but not brittle. It was suggested that this remarkable effect was due to its comparatively high moisture content. Consequently MFC acted both as a "conventional" reinforcement because of its fibrous structure and also indirectly as a plasticiser because its presence led to an increase in film moisture content.

Keyword
amylopectin films, microfibrillar cellulose, glycerol, mechanical properties, plasticiser
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8361 (URN)10.1016/j.carbpol.2006.08.008 (DOI)000245846200012 ()2-s2.0-33947172649 (Scopus ID)
Note
QC 20100831Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2010-11-22Bibliographically approved
2. Properties of amylopectin/montmorillonite composite films containing a coupling agent
Open this publication in new window or tab >>Properties of amylopectin/montmorillonite composite films containing a coupling agent
2007 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 104, no 6, 4160-4167 p.Article in journal (Refereed) Published
Abstract [en]

The addition of clay to polymers has the combined effects of enhancing both the strength / stiffness and the barrier properties. This investigation presents a novel approach to further enhance the strength / stiffness of cast plasticized amylopectin (AP)/Na+-montmorillonite clay films using a water-soluble coupling agent, poly[(isobutylene-alt-maleic acid, ammonium salt)-co-(isobutylene-alt-maleic anhydride)], between the filler and the matrix. The addition of clay increased the strength and stiffness of the film and the addition of 0.4 parts of a coupling agent per 1 part clay further increased these properties. The trends were the same after each treatment, and there were always significant differences in stiffness and strength between the films without clay and with clay with 0.4 parts of the coupling agent. The increase in stiffness / strength in the presence of a small amount of the coupling agent suggested that it had a bridging effect, presumably through strong secondary bonds to the clay and to the matrix. Infrared spectroscopy and moisture swelling experiments indicated that ester bonds were formed between the coupling agent and AP. X-ray spectroscopy and transmission electron microscopy revealed that the clay-particle / polymer structure was qualitatively independent of the presence of the coupling agent showing a mixture of intercalated clay stacks and exfoliated platelets.

Keyword
amylopectin, montmorillonite, composite, mechanical properties, coupling agent
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8362 (URN)10.1002/app.26172 (DOI)000246128400087 ()2-s2.0-34249048863 (Scopus ID)
Note
QC 20100831Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2010-11-22Bibliographically approved
3. Enhancement of the wet properties of transparent chitosan-acetic-acid-salt films using microfibrillated cellulose
Open this publication in new window or tab >>Enhancement of the wet properties of transparent chitosan-acetic-acid-salt films using microfibrillated cellulose
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2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 8, 2398-2403 p.Article in journal (Refereed) Published
Abstract [en]

This report presents a new route to enhance the wet properties of chitosan-acetic-acid-salt films using microfibrillated cellulose (MFC). The enhancement makes it easier to form chitosan-acetic-acid-salt films into various shapes at room temperature in the wet state. Chitosan with MFC was compared with the well-known buffer treatment. It was observed that films containing 5 wt % MFC were visually identical to the buffered/unbuffered films without MFC. Field-emission scanning electron microscopy indicated that MFC formed a network with uniformly distributed fibrils and fibril bundles in the chitosan matrix. The addition of MFC reduced the risk of creases and deformation in the wet state because of a greater wet stiffness. The wet films containing MFC were also extensible. Although the stiffness, strength and extensibility were highest for the buffered films, the wet strength of the MFC-containing unbuffered films was sufficient for wet forming operations. The effects of MFC on the mechanical properties of the dry chitosan films were small or absent. It was concluded that the addition of MFC is an acceptable alternative to buffering for shaping chitosan films/products in the wet state. The advantages are that the "extra" processing step associated with buffering is unnecessary and that the film matrix remains more water-soluble.

Keyword
Acetic acid, Mechanical properties, Scanning electron microscopy, Solubility, Stiffness, Wetting Buffer treatment, Chitosan-acetic-acid-salt films, Film matrix, Microfibrillated cellulose
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8363 (URN)10.1021/bm070246x (DOI)000248755000010 ()2-s2.0-34548207331 (Scopus ID)
Note
QC 20100831Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2010-11-22Bibliographically approved
4. Transport Properties of Nanocomposites Based on Polymers and Layered Inorganic Fillers
Open this publication in new window or tab >>Transport Properties of Nanocomposites Based on Polymers and Layered Inorganic Fillers
2009 (English)In: Packaging Nanotechnology / [ed] Amar K Mohanty; Manjusri Misra; Hari Singh Nalwa, Stevenson Ranch, Calif.: American Scientific Publishers , 2009Chapter in book (Other academic)
Place, publisher, year, edition, pages
Stevenson Ranch, Calif.: American Scientific Publishers, 2009
Series
Nanotechnology book series, 22
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-24290 (URN)1-58883-105-1 (ISBN)
Note
QC 20100831. Tidigare titel: Transport properties of polymer-layered mineral nanocompositesAvailable from: 2010-08-31 Created: 2010-08-31 Last updated: 2010-11-22Bibliographically approved

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