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Effects on Oxygen-barrier Properties of Pretreating Paperboard with a Starch–Poly(Vinyl Alcohol) Blend before Polyethylene Extrusion
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. Karlstad University.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.ORCID iD: 0000-0002-1256-1708
2016 (English)In: Packaging technology and science, ISSN 0894-3214Article in journal (Refereed) Published
Place, publisher, year, edition, pages
John Wiley & Sons, 2016.
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-38336DOI: 10.1002/pts.2210OAI: oai:DiVA.org:kau-38336DiVA, id: diva2:867839
Note

ej publicerats än

Available from: 2015-11-06 Created: 2015-11-06 Last updated: 2018-03-26Bibliographically approved
In thesis
1. Effects of plasticizing and crosslinking on the mechanical and barrier properties of coatings based on blends of starch and poly(vinyl alcohol)
Open this publication in new window or tab >>Effects of plasticizing and crosslinking on the mechanical and barrier properties of coatings based on blends of starch and poly(vinyl alcohol)
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In the last decades, intensive research has been carried out in order to replace oil-based polymers with bio-based polymers due to growing environmental concerns. So far, most of the barrier materials used in food packaging are petroleum-based materials. The purpose of the barrier is to protect the packaged food from oxygen, water vapour, water and fat. The mechanical and barrier properties of coatings based on starch-plasticizer and starch-poly(vinyl alcohol) (PVOH)-plasticizer blends have been studied in the work described in this thesis. The plasticizers used were glycerol, polyethylene glycol and citric acid. In a second step, polyethylene coatings were extruded onto paperboard pre-coated with a starch-PVOH-plasticizer blend. The addition of PVOH to the starch increased the flexibility of the film. Curing of the film led to a decrease in flexibility and an increase in tensile strength. The flexibility of the starch-PVOH films was increased more when glycerol or polyethylene glycol was added than citric acid. The storage modulus of the starch-PVOH films containing citric acid increased substantially at high temperature.

It was seen that the addition of polyethylene glycol or citric acid to the starch-PVOH blend resulted in an enrichment of PVOH at the surface of the films. Tensile tests on the films indicated that citric acid acted as a compatibilizer and increased the compatibility of the starch and PVOH in the blend. The addition of citric acid to the coating recipe substantially decreased the water vapour transmission rate through the starch-PVOH coated paperboard, which indicated that citric acid acts as a cross-linker for starch and/or PVOH. The starch-PVOH coatings containing citric acid showed oxygen-barrier properties similar to those of pure PVOH or of a starch-PVOH blend without plasticizer when four coating layers were applied on a paperboard. The oxygen-barrier properties of coatings based on a starch-PVOH blend containing citric acid indicated a cross-linking and increase in compatibility of the starch-PVOH blends.

Polyethylene extrusion coating on a pre-coated paperboard resulted in a clear reduction in the oxygen transmission rate for all the pre-coating formulations containing plasticizers. The addition of a plasticizer to the pre-coating reduced the adhesion of polyethylene to pre-coated board. Polyethylene extrusion coating gave a board with a lower oxygen transmission rate when the paperboard was pre-coated with a polyethylene-glycol-containing formulation than with a citric-acid-containing formulation. The addition of polyethylene glycol to pre-coatings indicated an increase in wetting of the pre-coated paperboard by the polyethylene melt, and this may have sealed the small defects in the pre-coating leading to low oxygen transmission rate. The increase in brittleness of starch-PVOH films containing citric acid at a high temperature seemed to have a dominating effect on the barrier properties developed by the extrusion coating process. 

Abstract [en]

Over the last few decades, industry and academia have made joint efforts to generate knowledge about renewable barrier materials in order to replace the oil-based barrier materials currently used in food packaging. This work has focused on the possibility of producing a material with high oxygen barrier properties including polyethylene as a moisture protection.

The flexibility of starch films was increased by adding poly(vinyl alcohol) (PVOH) to the starch and the addition of a plasticizer to the starch-PVOH blend films further increase the flexibility of the films. The plasticizers used were glycerol, polyethylene glycol and citric acid. Curing of the films reduce their flexibility. The addition of citric acid to a starch-PVOH blend increased the compatibility of the starch-PVOH blend and affected the barrier properties of the coating layers containing citric acid. When a sufficient number of coating layers was applied, the starch-PVOH-citric-acid coatings showed oxygen-transmission-rate-values similar to those of the pure PVOH and of the starch-PVOH blend without plasticizers. Polyethylene extrusion coating on pre-coated paperboard resulted in a clear reduction in the oxygen transmission rate of all the pre-coating recipes based on starch-PVOH blends. The polyethylene extrusion coating showed a higher oxygen transmission rate for a board pre-coated with citric-acid-containing recipes than for a board pre-coated with polyethylene-glycol-containing recipes.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2015. p. 42
Series
Karlstad University Studies, ISSN 1403-8099 ; 2015:54
Keywords
Citric acid, Glycerol, Polyethylene glycol, Barrier properties, Starch, Mechanical properties, Polyvinyl alcohol, Adhesion, Cross linking, Extrusion coating
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-38337 (URN)978-91-7063-673-8 (ISBN)
Presentation
2015-12-17, 9C203, Nyquistsalen, Karlstad University, Karlstad University, Dept. of Engineering and Chemical Sciences, Karlstad, 10:15 (English)
Opponent
Supervisors
Funder
Knowledge FoundationBillerudKorsnäs AB
Available from: 2015-11-26 Created: 2015-11-06 Last updated: 2017-08-11Bibliographically approved
2. Effects of plasticizing and crosslinking on coatings based on blends of starch-PVOH and starch-lignin
Open this publication in new window or tab >>Effects of plasticizing and crosslinking on coatings based on blends of starch-PVOH and starch-lignin
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A barrier material is usually needed on a fiber-based food package to protect the packed food from gases and moisture and thus maintain its quality. Barrier materials presently used in food packaging applications are mostly petroleum-based polymers. Over the last few decades, efforts have been made to replace petroleum-based materials with bio-based materials. The present work has focused on the possibility of using a natural barrier material on a fiber-based food package and the  effects of plasticizing and cross-linking on the mechanical and barrier properties, and the stability in water of coatings based on starch-poly(vinyl alcohol) (PVOH) and starch-lignin blends.

The flexibility of the starch films was increased by adding PVOH further by adding a plasticizer. It was shown that citric acid can act as a compatibilizer and cross-linker for starch and PVOH, and the use of citric acid may slow down the diffusion of both oxygen and water vapor if a multilayer coating strategy is used. The addition of polyethylene glycol to the pre-coating recipe resulted in a lower oxygen transmission rate through polyethylene-extruded board than when citric acid was added to the pre-coating. The flexibility of the barrier coatings and the properties of the base substrate affect the cracking tendency of the barrier coatings during the creasing and folding of a barrier-coated board.

The addition of lignin to the starch reduced the migration of starch from the starch-lignin films and the addition of ammonium zirconium carbonate as a cross-linker reduced the migration of both starch and lignin from the films. The addition of starch to the lignin solution increased the solubility of lignin at low pH, and the pilot-coated board showed a significant decrease in migration of lignin from the coatings containing ammonium zirconium carbonate when the pH of the coating solution was decreased.

Abstract [en]

A barrier material is usually needed on a fiber-based food package to maintain quality by protecting packed food from gases and moisture. Over the last few decades, efforts have been made to replace petroleum-based materials with bio-based materials. The present work has focused on the possibility of using a natural barrier material on fiber-based food packaging materials, and the effects of plasticizing and cross-linking on the mechanical and barrier properties and on the stability in water of coatings based on starch-PVOH and starch-lignin blends have been evaluated.

Citric acid can act as a compatibilizer and cross-linker for starch and PVOH, and the use of citric acid may retard the diffusion of both oxygen and water vapor if a multilayer coating strategy is used. A polyethylene extrusion coating on a board pre-coated with a recipe containing polyethylene glycol resulted in a greater reduction in the rate of oxygen transmission than through a board pre-coated with a recipe containing citric acid. The addition of lignin to the starch solution decreased the migration of starch from the starch-lignin films, and the addition of ammonium zirconium carbonate as a cross-linker decreased the migration of both starch and lignin from the films. 

Place, publisher, year, edition, pages
Karlstads universitet, 2018. p. 69
Series
Karlstad University Studies, ISSN 1403-8099 ; 2018:14
Keywords
Citric acid, Glycerol, Polyethylene glycol, Barrier coatings, Starch, Lignin, Mechanical properties, Poly(vinyl alcohol), Creasing, Adhesion, Cross-linking, Extrusion coating
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-66853 (URN)978-91-7063-844-2 (ISBN)978-91-7063-939-5 (ISBN)
Public defence
2018-05-16, 1B306, Fryxellsalen, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2018-04-25 Created: 2018-03-26 Last updated: 2018-04-25Bibliographically approved

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Javed, AsifUllsten, HenrikJärnström, Lars

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