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Plasticized xyloglucan for improved toughness-Thermal and mechanical behaviour
KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.ORCID-id: 0000-0001-5818-2378
2012 (engelsk)Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, nr 4, s. 2532-2537Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Tamarind seed xyloglucan is an interesting polysaccharide of high molar mass with excellent thermomechanical properties. Several plasticizers were studied in order to facilitate thermal processing and improve toughness (work to fracture) of xyloglucan film materials: sorbitol, urea, glycerol and polyethylene oxide. Films of different compositions were cast and studied by thermogravimetric analysis (TGA), calorimetry (DSC), dynamic mechanical thermal analysis (DMA) and tensile tests. Results are analysed and discussed based on mechanisms and practical considerations. Highly favourable characteristics were found with XG/sorbitol combinations, and the thermomechanical properties motivate further work on this material system, for instance as a matrix in biocomposite materials.

sted, utgiver, år, opplag, sider
Elsevier, 2012. Vol. 87, nr 4, s. 2532-2537
Emneord [en]
Glass transition, Mechanical properties, Plasticization, Polymer films, Xyloglucan
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-90895DOI: 10.1016/j.carbpol.2011.11.024ISI: 000299969800023Scopus ID: 2-s2.0-84865653433OAI: oai:DiVA.org:kth-90895DiVA, id: diva2:507973
Merknad

QC 20150716

Tilgjengelig fra: 2012-03-07 Laget: 2012-03-05 Sist oppdatert: 2017-12-07bibliografisk kontrollert
Inngår i avhandling
1. Xyloglucan-based polymers and nanocomposites – modification, properties and barrier film applications
Åpne denne publikasjonen i ny fane eller vindu >>Xyloglucan-based polymers and nanocomposites – modification, properties and barrier film applications
2012 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Biopolymers from renewable resources are of interest for packaging applications as an alternative to conventional petroleum-based polymers. One of the major application areas for biopolymers is food packaging, where a candidate polymer should meet critical requirements such as mechanical and oxygen barrier performance, also in humid conditions. Starch has long been used in certain packaging applications, either in plasticized state or blended with other polymers. However, native starch has high sensitivity to water and low mechanical and barrier performance. Recently, wood-derived hemicelluloses have been extensively studied as oxygen barrier films, but suffer from low film-forming ability and mechanical performance. In the present study, xyloglucan (XG) from tamarind seed waste is explored as an alternative high-performance biopolymer in packaging applications. The obstacles of polysaccharides in terms of moisture sensitivity and processability are addressed in this thesis.

In Paper I, film properties of XG were studied. XG has a cellulose backbone, but unlike cellulose, it is mostly soluble in water forming highly robust films. Moisture sorption isotherms, tensile tests and dynamic mechanical thermal analysis were performed. Enzymatic modification (partial removal of galactose in side chains of XG) was performed to study the effect of galactose on solubility and filmforming characteristics. XG films showed lower moisture sorption than starch. Stiffness and tensile strength were very high of the order of 4 GPa and 70 MPa respectively, with considerable ductility and toughness. The thermomechanical performance was very high with a softening temperature near 260 ºC.

In Paper II, several plasticizers were studied in order to facilitate thermal processing of XG films: sorbitol, urea, glycerol and polyethylene oxide. Films of different compositions were prepared and studied for thermomechanical and tensile properties. Highly favorable characteristics were found with XG/sorbitol system. A large drop in glass transition temperature (Tg) of XG of the order of 100 ºC with 20 - 30 wt% sorbitol was observed with an attractive combination of increased toughness.

In Paper III, XG was chemically modified and the structure-property relationship of modified XG studied. XG modification was performed using an approach involving periodate oxidation followed by reduction. The oxidation is highly regioselective, where the side chains of XG are mostly affected with the cellulose backbone well-preserved as noticed from MALDI-TOF-MS and carbohydrate analysis. Films were cast from water and characterized by dynamic mechanical thermal analysis, dynamic water vapor sorption, oxygen transmission analysis and tensile tests. Property changes were interpreted from structural changes. The regioselective modification results in new types of cellulose derivatives without the need for harmful solvents.

In Paper IV, moisture durability of XG was addressed by dispersing montmorillonite (MTM) platelets in water suspension. Oriented bionanocomposite coatings with strong in-plane orientation of clay platelets were prepared. A continuous water-based processing approach was adopted in view of easy scaling up. The resulting nanocomposites were characterized by FE-SEM, TEM, and XRD. XG adsorption on MTM was measured by quartz crystal microbalance analysis. Mechanical and gas barrier properties were measured, also at high relative humidity. The reinforcement in mechanical properties and effects on barrier properties were remarkable, also in humid conditions.

In Paper V, cross-linked XG/MTM composite was prepared with high clay content (ca. 45 vol%) by an industrially scalable “paper-making” method. Instead of using cross-linking molecules, cross-linking sites were created on the XG chain by selective oxidation of side chains. The in-plane orientation of MTM platelets were studied using XRD and FE-SEM. The mechanical properties and barrier performance were evaluated for the resulting 'nacre-mimetic' nanocomposites. The elastic modulus of cross-linked nanocomposites is as high as 30 GPa, one of the stiffest bionanocomposites reported.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2012. s. ix, 61
Serie
Trita-CHE-Report, ISSN 1654-1081 ; 2012:53
Emneord
xyloglucan, packaging, oxygen barrier, nanocomposites
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-107043 (URN)978-91-7501-528-6 (ISBN)
Disputas
2012-12-21, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20121107

Tilgjengelig fra: 2012-12-07 Laget: 2012-12-06 Sist oppdatert: 2012-12-07bibliografisk kontrollert

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