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Tamarind seed xyloglucan: a thermostable high-performance biopolymer from non-food feedstock
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
KTH, Skolan för bioteknologi (BIO), Glykovetenskap.ORCID-id: 0000-0001-9832-027X
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Biokompositer.ORCID-id: 0000-0001-5818-2378
2010 (Engelska)Ingår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 20, nr 21, s. 4321-4327Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Polysaccharide biopolymers from renewable resources are of great interest as replacements for petroleum-based polymers since they have lower cradle-to-grave non-renewable energy use and greenhouse gas emissions. Starch is widely used as a packaging material but is based on food resources such as potato or corn, and suffers from high sensitivity to water vapor even under ambient conditions. For the first time, xyloglucan (XG) from tamarind seed waste is explored as an alternative high-performance biopolymer from non-food feedstock. XG is purified, and dissolved in water to cast films. Moisture sorption isotherms, tensile tests and dynamic mechanical thermal analysis are performed. Glycerol plasticization toughening and enzymatic modification (partial removal of galactose in side chains of XG) are attempted as means of modification. XG films show much lower moisture sorption than the amylose component in starches. Stiffness and strength are very high, with considerable ductility and toughness. The thermal stability is exceptionally high and is approaching 250 degrees C. Glycerol plasticization is effective already at 10% glycerol. These observations point towards the potential of XG as a "new'' biopolymer from renewable non-food plant resources for replacement of petroleum-based polymers.

Ort, förlag, år, upplaga, sidor
2010. Vol. 20, nr 21, s. 4321-4327
Nyckelord [en]
Ambient conditions, Cast film, Dynamic mechanical thermal analysis, Enzymatic modification, Food plants, Food resources, High sensitivity, Moisture sorption, Moisture sorption isotherms, Non-renewable energy, Renewable resource, Side chains, Tensile tests, Thermal stability, Xyloglucans
Nationell ämneskategori
Fysikalisk kemi Materialteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-27854DOI: 10.1039/c0jm00367kISI: 000277832700008Scopus ID: 2-s2.0-77952522070OAI: oai:DiVA.org:kth-27854DiVA, id: diva2:385804
Anmärkning
QC 20110112Tillgänglig från: 2011-01-12 Skapad: 2011-01-03 Senast uppdaterad: 2017-12-11Bibliografiskt granskad
Ingår i avhandling
1. Xyloglucan-based polymers and nanocomposites – modification, properties and barrier film applications
Öppna denna publikation i ny flik eller fönster >>Xyloglucan-based polymers and nanocomposites – modification, properties and barrier film applications
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2012. s. ix, 61
Serie
Trita-CHE-Report, ISSN 1654-1081 ; 2012:53
Nyckelord
xyloglucan, packaging, oxygen barrier, nanocomposites
Nationell ämneskategori
Polymerteknologi
Identifikatorer
urn:nbn:se:kth:diva-107043 (URN)978-91-7501-528-6 (ISBN)
Disputation
2012-12-21, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20121107

Tillgänglig från: 2012-12-07 Skapad: 2012-12-06 Senast uppdaterad: 2012-12-07Bibliografiskt granskad

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