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Mechanical and physical properties of chitosan and whey blended with poly(ε- caprolactone)
KTH, Superseded Departments, Fibre and Polymer Technology.
KTH, Superseded Departments, Fibre and Polymer Technology.
KTH, Superseded Departments, Fibre and Polymer Technology.
KTH, Superseded Departments, Fibre and Polymer Technology.
2002 (English)In: International Journal of Polymeric Materials, ISSN 0091-4037, E-ISSN 1563-535X, Vol. 51, no 3, 275-289 p.Article in journal (Refereed) Published
Abstract [en]

Properties important for packaging were studied on blends of 0-15 wt% poly( caprolactone) and chitosan and a whey-protein-isolate. The blends were obtained by solution mixing, and films were produced by solvent casting. Transparency was measured by UV/VIS spectroscopy and the printability was qualitatively estimted by using a red ethanol dye. Mechanical properties of solid films and seals were assessed by tensile tests. Stiffness and folding endurence were also measured. The blend morphology was characterized by scanning electron microscopy. It was found that all the blends were transparent. The whey-protein-isolate had the best printability properties and printability remained in the poly( -caprolactone)-blends. Film stiffness decreased and strain at break increased strongly when the pure chitosan and the pure whey-protein-isolate were wetted. The addition of poly( -caprolactone) to chitosan and whey-protein-isolate had only a moderate effect on the toughness properties but a strong effect on the modulus which could be predicted by the Halpin-Tsai model. The modulus of the whey-protein-isolate increased and the modulus of the chitosan decreased with the addiion of poly( -caprolactone). It was found that it was impossible to seal chitosan with a standard heat-pulse sealing technique. The whey-protein-isolate was sealable but the strength of the seals was lower than the intrinsic strength of the pure whey-protein-isolate. The folding endurance properties of chitosan and its blends were far better than those of the whey-protein-isolate and its blends.

Place, publisher, year, edition, pages
2002. Vol. 51, no 3, 275-289 p.
Keyword [en]
Poly(ε-caprolactone), Chitosan, Whey, Physical Properties, Optical Properties, Blends
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-5128DOI: 10.1080/00914030213038OAI: oai:DiVA.org:kth-5128DiVA: diva2:7913
Note
QC 20101013Available from: 2005-05-18 Created: 2005-05-18 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Strategies to improve the aging, barrier and mechanical properties of chitosan, whey and wheat gluten protein films
Open this publication in new window or tab >>Strategies to improve the aging, barrier and mechanical properties of chitosan, whey and wheat gluten protein films
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Chitosan, Whey Protein Isolate (WPI) and vital wheat gluten (WG) are three biomaterials that have quite promising properties for packaging purposes. They have good film forming properties and good gas barrier properties in dry conditions. Moreover, because they are produced from industrial waste of food processing, they offer an ecological advantage over polymers made from petroleum. However, their physicochemical characteristics still must be improved for them to be of commercial interest for the food packaging industry. The purpose of this work was to study different strategies aiming to improve the water resistance and aging properties of these polymers, which are some of the key disadvantages of these materials.

The produced solution cast chitosan and WPI films were characterised with scanning electron microscopy (SEM), density measurements and thermogravimetry. The water vapour transmission rate was determined at a relative humidity of 11%. In the first part, mechanical properties of solid films and seals were assessed by tensile testing. WG film’s tensile properties and oxygen and water vapour permeabilities were measured as a function of aging time. The changes in the protein structure were determined by infrared spectroscopy and size-exclusion high-performance liquid chromatography and the film structure was revealed by optical and scanning electron microscopy. Gluten-clay nanocomposites were characterised by tensile testing, X-ray diffraction and transmission electron microscopy.

The incorporation of a hydrophobic biodegradable polymer, poly ( ε-caprolactone), PCL, in both chitosan and whey protein, yielded a significant decrease in water vapour transmission rate. It was observed that a certain amount of the PCL particles were ellipsoidal in chitosan and fibrous in WPI. The obtained data also indicated that the particle shape had an important influence in the water vapour transmission rate.

In the second part, the aging properties of WG films, plasticized with glycerol and cast from water/ethanol solutions with pH=4 or pH=11 were investigated. WG films made from alkaline solutions were mechanically more time-stable than the acidic ones, the latter being initially very ductile but turning brittle towards the end of the aging period. The protein solubility measurements indicated that the protein structure of the acidic films was initially significantly less aggregated than the in basic films. During aging the acidic films lost more mass than the basic films through slow evaporation of volatiles (water/ethanol) and through migration of glycerol to the paper support. The oxygen permeability was also lower for the basic films.

In the last part, the properties of new and aged glycerol-plasticized WG films at acidic and basic conditions containing ≤4.5 wt% natural or quaternary-ammonium-salt-modified montmorillonite were studied. Films of WG with montmorillonite were possible to produce by solution casting. The aging rate of acidic and basic films was unaffected by the incorporation of clay. However, the large reduction in water vapour permeability for most systems suggested that the clay sheets were evenly distributed within the films. The film prepared from basic solution and containing natural clay was almost completely exfoliated as revealed by transmission electron microscopy and X-ray diffraction. The best water vapour barrier properties were obtained by using modified clay.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 68 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2005:14
Keyword
Chemistry, biodegradable polymers, chitosan, whey protein, wheat gluten, poly(ε-caprolactone), montmorillonite, food packaging, permeability, mechanical properties, aging, pH, solubility, migration, solution casting., Kemi
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-208 (URN)91-7178-049-1 (ISBN)
Public defence
2005-05-27, K2, Teknikringen 28, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101013Available from: 2005-05-18 Created: 2005-05-18 Last updated: 2010-10-13Bibliographically approved

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