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Biodegradable Blends and Nanocomposite Films with Amylopectin, Poly(lactic acid) and Chitosan Matrices
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [sv]

Användningan av engångsförpackningar har ökat kraftigt de senaste åren. Den absolut största delen av dessa förpackningar tillverkars av oljebaserade plaster såsom polyetylen (PE) och polypropylen (PP). Dessa har även en oerhört lång nedbrytningstid, vilket gör det viktigt att finna mer miljövänliga alternativ. Exempel på förnyelsebara och bionedbrytbara material är amylopektin (AP), kitosan och polymjölksyra (PLA). I denna avhandling presenteras arbete med att utveckla dessa material för att öka deras chanser att i framtiden användas som, förslagsvis, förpackningsmaterial. Nanokompositer baserade på AP och kitosan tillverkas genom att montmorillonitlera (MMT) och/eller mikrofibrillär cellulosa (MFC) inkorporeras i matrisen. En metod där en vattenlöslig reaktiv kompatibilisator används för att öka adhesionen mellan MMT och AP-matrisen presenteras. Mekanisk prövning visar på ökad styvhet and styrka när kompatibilisatorn används. Påverkan av olika värmebehandlingar innan, under och efter filmbildning redovisas. Med infraröd strålning (IR) och absorbtionsmätningar följs rektionen mellan fyllmedel och matris. Studier på MFC/AP visar att användningen av MFC leder till en anmärkningsvärd effect, det vanligen spröda amylopektinmaterialet blir en böjbar komposit utan att använda mjukgörare. Detta är möjligt tack vare att MFC är mycket hydroskopisk och, som de termiska mätningarna visar, binder vatten väldigt hart. Även mekaniska prövning av fiberkompositerna har studerats. Fiberkompositer baserade på kitosan har studerats tillsammans med en allmänt vedertagen buffringsmetod. De mekaniska egenskaperna i vått och torrt tillstånd har genom detta kunna förbättrats. Fiber och lerdistributionen i samtliga nanokompositer har även analyserats med X-ray, transmissions electron mikroskop (TEM), skanning electron mikroskop (SEM) och optiskt mikroskop (OM). Slutligen har PLA blandningar med AP producerats genom smältblandning. För att öka affiniteten mellan de två komponenterna har en nedbrytbar sort av polyetylenvinylalkohol (EVOH), med hög halt vinyl alkohol, använts som kompatibilisator. Den morphologiska stukturen har studerats genom SEM, OM, och Raman spektroskopi. En bra mixing erhölls även om en visss fasseparation kunde ses. När även glycerol ingick i systemet kunde en lite bättre dispersion fås.

Abstract [en]

As the use of disposable materials is rapidly increasing so are the issues with waste handling. Today, the majority of the materials used for these applications, i.e. food packages, are oil-based plastics such as polyethylene and polypropylene. Therefore, it is important to find biodegradable materials made from renewable resources for this huge growing market. Amylopectin (AP), poly(lactic acid) (PLA) and chitosan are three interesting materials for these applications. In this thesis, several ways and methods are evaluated to improve these materials and their chances of becoming future biodegradable bulk materials. AP and chitosan based nanocomposites were created by incorporating montmorillonite (MMT) and/or microfibrillated cellulose (MFC) into the materials. Also, a novel approach of using a water-soluble coupling agent to enhance the strength and stiffness of AP/MMT-composites by increasing the adhesion between the matrix and the filler is presented. Through infrared spectroscopy (IR) and moisture absorption measurements the reaction was analyzed. Mechanical testing showed that an improved strength and stiffness was obtained with the use of the coupling agent. By using appropriate treatment, before, during and after filmmaking, the effect of the coupling agent could be further increased. The AP/MFC composites showed that MFC bind water very tightly, creating a foldable material based on the naturally brittle AP. Chitosan has been investigated to study the mechanical properties of films in dry and wet conditions using MFC and/or a well-known buffer treatment. The addition of MFC prevented extensive shrinkage in the wet condition due to increased wet stiffness. The fibre and clay distribution in all the composites have been analyzed with X-ray, transmission electron microscopy, scanning electron microscopy and optical microscopy. Furthermore, PLA/AP blends were produced through melt mixing. In efforts to improve the affinity between the two constituents, a biodegradable grade of poly(ethylene-co-vinyl alcohol) EVOH, with high vinyl alcohol content, was used as a compatibilizer. Good mixing were obtained even if some phase separated structure could be seen. The presence of glycerol slightly increased the dispersion of the secondary phase in PLA.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 61 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:29
Keyword [en]
amylopectin, chitosan, microfibrillated cellulose, nanocomposite, montmorillonite, coupling agent
Keyword [sv]
amylopektin, kitosan, mikrofibrillär cellulose, nanokomposit, montmorillonit, kompatibilisator
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-4731ISBN: 978-91-7178-939-6 (print)OAI: oai:DiVA.org:kth-4731DiVA: diva2:13669
Public defence
2008-05-30, F3, Lindstedtsvägen 26, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20100831Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2010-08-31Bibliographically 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
Show others...
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
Show others...
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. Nanocomposites based on amylopectin, microfibrillated cellulose and montmorillonite
Open this publication in new window or tab >>Nanocomposites based on amylopectin, microfibrillated cellulose and montmorillonite
(English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344Article in journal (Other academic) Submitted
Keyword
amylopectin, montmorillonite, microfibrillated cellulose (MFC), nanocomposite, mechanical properties
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8364 (URN)
Note
QS 20120328Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2012-03-28Bibliographically approved
5. Melt blends of PLA and amylopectin using EVOH as a compatibilizer: Part I: Morpological characterization
Open this publication in new window or tab >>Melt blends of PLA and amylopectin using EVOH as a compatibilizer: Part I: Morpological characterization
(English)Manuscript (Other academic)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8365 (URN)
Note
QC 20100831Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2010-08-31Bibliographically approved
6. 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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Citation style
  • apa
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  • modern-language-association-8th-edition
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Output format
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