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The influence of moisture content on the polymer structure of polyvinyl alcohol in dispersion barrier coatings and its effect on the mass transport of oxygen
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Bologna University.
Bologna University.
Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. (Materialvetenskap)ORCID iD: 0000-0002-1609-8909
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(English)In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028Article in journal (Other academic) Epub ahead of print
Abstract [en]

This paper presents a study of the effect of moisture on the gas permeability of polyvinyl alcohol (PVOH) and PVOH–kaolin dispersion barrier coatings. The oxygen permeability was measured at different humidity levels, and the material properties were characterized under the same conditions: polymer crystallinity, kaolin concentration, and kaolin orientation were all evaluated. The experimental results revealed that the water plasticizes the PVOH material of the coatings, and the presence of kaolin filler is unable to affect such behavior significantly. The PVOH crystallinity was affected drastically by the humidity, as water melts polymer crystallites, which is a reversible process under removal of water. The permeability data were analyzed using a thermodynamicbased model able to account for the water effect on both the solubility of the gas and the diffusivity coefficients in the polymer and composite. The results showed good agreement between the model’s predictions and the experimental data in terms of the overall permeability of the material.

Place, publisher, year, edition, pages
Springer.
Keyword [en]
Mass transport, Permeability, Modeling, Barrier coating, Moisture, Kaolin, PVOH
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-47462DOI: 10.1007/s11998-017-9937-2OAI: oai:DiVA.org:kau-47462DiVA: diva2:1055712
Funder
Knowledge Foundation, 20100268Stora Enso
Available from: 2016-12-13 Created: 2016-12-07 Last updated: 2017-08-25Bibliographically approved
In thesis
1. Structure-Performance Relations of Oxygen Barriers for Food Packaging
Open this publication in new window or tab >>Structure-Performance Relations of Oxygen Barriers for Food Packaging
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Food packaging should ensure the safety and quality of food, minimize spoilage and provide an easy way of storing and handling it. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. Using both experimental data and computer modelling, this thesis explains some aspects of how the structure of barrier coatings influences the mass transport of oxygen with the aim of obtaining essential knowledge that can be used to optimize the performance of barriers.

Barrier coatings are produced from polyvinyl alcohol and kaolin blends that are coated onto a polymeric support. The chemical and physical structures of these barriers were characterized according to their influence on permeability in various climates. At a low concentration of kaolin, the crystallinity of polyvinyl alcohol decreased; in the thinner films, the kaolin particles were orientated in the basal plane of the barrier coating. The experimental results indicated a complex interplay between the polymer and the filler with respect to permeability.

A computer model for permeability incorporating theories for the filled polymeric layer to include the polymer crystallinity, addition of filler, filler aspect ratio and surrounding moisture was developed. The model shows that mass transport was affected by the aspect ratio of the clay in combination with the clay concentration, as well as the polymer crystallinity. The combined model agreed with the experiments, showing that it is possible to combine different theories into one model that can be used to predict the mass transport.

Four barrier coatings: polyethylene, ethylene vinyl alcohol + kaolin, latex + kaolin and starch were evaluated using the parameters of greenhouse gas emissions and product costs. After the production of the barrier material, the coating process and the end-of-life handling scenarios were analysed, it emerged that starch had the lowest environmental impact and latex + kaolin had the highest.

Abstract [en]

Food packaging is required to secure the safety and quality of food, as well as minimize spoilage and simplify handling. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods.

This thesis focuses on the mass transport of oxygen in order to gain deeper knowledge of, and thereby optimise, the performance of barrier coatings. This experimental study, together with computer modelling, characterized the structure of barrier materials with respect to the mass transport process. The performance of the barriers was evaluated based on the parameters of environmental impact and product costs. As the long-term aim is to use non-petroleum-based barrier coatings for packaging, these should be evaluated by assessing the properties of the material in question, its functionality and its environmental impact to provide more insight into which materials are desirable as well as to develop technology.

The results from this study indicate that several parameters (the orientation, concentration and aspect ratio of the clay and the polymer crystallinity) influence the properties of a barrier. Using this knowledge, researchers and food packaging engineers can work toward improving and customising renewable barriers.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2017. 100 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2017:3
Keyword
Barrier coating, Permeability, Dynamic Mass Transport, Modelling, Diffusion, Polymer, Dispersion, Kaolin, LCA, Starch, Hemicellulose
National Category
Polymer Technologies Textile, Rubber and Polymeric Materials Computational Mathematics Food Engineering Composite Science and Engineering Paper, Pulp and Fiber Technology
Research subject
Materials Science
Identifiers
urn:nbn:se:kau:diva-47496 (URN)978-91-7063-738-4 (ISBN)978-91-7063-739-1 (ISBN)
Public defence
2017-02-10, Eva Eriksson, 21A342, Karlstad, 10:00 (English)
Opponent
Supervisors
Projects
VIPP
Funder
Knowledge Foundation, 20100268Stora Enso
Available from: 2017-01-24 Created: 2016-12-13 Last updated: 2017-12-05Bibliographically approved

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Nyflött, ÅsaMoons, EllenJärnström, LarsLestelius, Magnus
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