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Transport properties of chitosan and whey blended with poly(ε-caprolactone) assessed by standard permeability measurements and microcalorimetry
KTH, Superseded Departments, Polymer Technology.
KTH, Superseded Departments, Polymer Technology.
KTH, Superseded Departments, Polymer Technology.
KTH, Superseded Departments, Polymer Technology.
2001 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 42, no 9, 4401-4408 p.Article in journal (Refereed) Published
Abstract [en]

Blends of poly(p-caprolactone) (PCL) with chitosan and a whey-protein-isolate (WPI) were prepared by solution mixing and film casting. The purpose was to increase the water vapour resistivity of chitosan and whey by blending them with a hydrophobic biodegradable polymer. The water vapour transmission rate was determined by a standard technique and by a new technique based on microcalorimetry. The blends were characterised by scanning electron microscopy (SEM), density measurements and thermogravimetry. Oxygen permeability was measured on the pure components and on some of the blends. The incorporation of PCL yielded a pronounced decrease in water vapour transmission rate of both chitosan and the WPI measured at a relative humidity gradient of 11 to 0%. A volume content of 17-18% of PCL lowered the water vapour transmission rate by 70-90%. It was found that the majority of the PCL particles were ellipsoidal in chitosan and fibrous in the WPI and the data indicated that the particle shape had an important influence on the water vapour transmission rate. The large decrease in water vapour transmission rate was also due to a reduction in water solubility because of limited swelling of the constrained chitosan or WPI matrix in the presence of PCL. SEM revealed that the miscibility/compatibility between PCL and the matrices was good. The water vapour transmission rate of the films decreased with increasing vacuum-drying time of the chitosan and WPI solutions. Microcalorimetry provided accurate estimates of water vapour transmission rate. Furthermore. this technique proved to be very flexible and the water vapour transmission rate could be determined over a broad range of relative humidities in a single experiment.

Place, publisher, year, edition, pages
2001. Vol. 42, no 9, 4401-4408 p.
Keyword [en]
chitosan, whey, transport properties
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-5127DOI: 10.1016/S0032-3861(00)00680-7ISI: 000167050400049OAI: oai:DiVA.org:kth-5127DiVA: diva2:7912
Note
QC 20101005Available 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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