Effects of plasticizing and crosslinking on coatings based

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Effects of plasticizing and crosslinking,on coatings based on blends of starch. PVOH and starch lignin,Asif Javed,Faculty of Health Science and Technology. Chemical Engineering, DOCTORAL THESIS Karlstad University Studies 2018 14. Effects of plasticizing and crosslinking,Structural Studies. on coatings based and Modelling,on blends of starch.
PVOH Transport in Barrier,and starch lignin,Materials for Food Packaging. Asif Nyfl tt,LICENTIATE,DOCTORAL THESIS Karlstad,KarlstadUniversity. UniversityStudies,Studies 2018 14, Effects of plasticizing and crosslinking on coatings based on blends of starch PVOH. and starch lignin,Asif Javed,DOCTORAL THESIS,Karlstad University Studies 2018 14. urn nbn se kau diva 66853,ISSN 1403 8099,ISBN 978 91 7063 844 2 print.
ISBN 978 91 7063 939 5 pdf,The author,Distribution. Karlstad University,Faculty of Health Science and Technology. Department of Engineering and Chemical Sciences,SE 651 88 Karlstad Sweden. 46 54 700 10 00,Print Universitetstryckeriet Karlstad 2018. WWW KAU SE, Fibre based food packaging normally requires a barrier material to.
protect packed foodstuff from gases and moisture in order to ensure. food quality So far the barrier materials used in food packaging. applications have been mostly oil based polymers Over the last. decade efforts have been made to replace oil based barrier materials. with bio based materials due to growing environmental concerns and. due to the persistent increase in oil prices and oil scarcity The work. described in this thesis has focused on coatings based on blends of. starch poly vinyl alcohol PVOH and starch lignin for their potential. use as barrier materials in food packaging applications. The effects of plasticizing and crosslinking on mechanical and barrier. properties of coatings based on starch PVOH blends were investigated. the plasticizers used being glycerol polyethylene glycol and citric acid. The addition of PVOH to the starch increased the flexibility of the film. and the addition of a plasticizer further increased their flexibility. Curing of the films led to a decrease in flexibility and to an increase in. brittleness of the films containing citric acid at high temperature Citric. acid acted as a compatibilizer for starch and PVOH blend and a low. water vapour transmission rate through coatings containing citric acid. indicated that citric acid also acted as a cross linker The oxygen. barrier properties of the coatings reflected the compatibility and cross. linking of the starch PVOH blend containing citric acid. Polyethylene was extruded onto a paperboard pre coated with a starch. PVOH blend and this lowered the oxygen transmission rate for all the. pre coating recipes containing plasticizer The addition of a plasticizer. to the pre coating reduced the adhesion of polyethylene to the pre. coated board The increase in brittleness of the pre coating at a high. temperature and the increase in wetting of the pre coated board by the. PE melt can affect the barrier properties developed by the extrusion. coating The polyethylene coated board had a lower oxygen. transmission rate when the board was pre coated with a polyethylene. glycol containing recipe than when the board was pre coated with a. citric acid containing recipe, In order to convert a board into a package creasing and folding. operations are usually necessary The results showed that an increase. in brittleness of the barrier coating layer can increase the cracking. tendency of the layers after creasing and folding of the board The base. substrate can also affect the crack propagation in the barrier coating. layer Barrier coatings applied on the mineral coated side of the board. showed a greater tendency to crack than barrier coatings applied on the. uncoated side of the board The cracks in the barrier coating layers. seemed to follow the fibres when the coating was applied on the board. with a high susceptibility to fibre rising, The addition of lignin to the starch decreased the migration of starch. from the starch lignin films into the model liquids viz deionized water. alkaline buffer solution of pH 10 and food simulant B 3 w v acetic. acid solution The addition of ammonium zirconium carbonate as a. cross linking agent to the starch lignin blend increased the brittleness. of the film and decreased the migration of both starch and lignin from. the films in contact with a liquid Ammonium zirconium carbonate was. a better cross linker for starch and lignin when the pH of the starch. lignin solution was adjusted with ammonia rather than with NaOH. The addition of starch to the lignin solution increased the solubility in. the test liquid of the lignin in starch lignin blends at low pH levels The. migration into the model liquids of lignin from the paper with a pre. coating of a starch lignin blend containing ammonium zirconium. carbonate decreased with decreasing pH of the coating solutions. List of papers included in the thesis, I Javed A Ullsten H Ernstsson M J rnstr m L 2016 Study of. starch and starch PVOH blends and effects of plasticizers on. mechanical and barrier properties of coated paperboard Nordic Pulp. Paper Research Journal 31 3 499 510, II Javed A Ullsten H J rnstr m L 2016 Effects on oxygen barrier. properties of pre treatment of paperboard with starch poly vinyl. alcohol blends before polyethylene extrusion Packaging Technology. and Science doi 10 1002 pts 2210, III Javed A R tt P J rnstr m L Ullsten H 2018 Crack analysis of.
barrier coatings based on starch and starch PVOH with and without. plasticizer Accepted for publication in Nordic Pulp Paper Research. IV Javed A Ullsten H R tt P J rnstr m L 2018 Lignin. containing coatings for packaging materials Submitted for. publication, V Javed A R tt P J rnstr m L Ullsten H 2018 Lignin. containing coatings for packaging materials pilot trials Submitted for. publication,Author s contribution, I Principal author Prepared the samples and designed the experiment. Carried out all the experiments except for the X Ray Photoelectron. Spectroscopy, II Principal author Prepared the samples and designed the experiment. Performed all the laboratory work except for the PE extrusion coating. III Principal author Planned and performed all the experimental work. with the exception of SEM images, IV Principal author Planned and performed all the experimental work. V Principal author Planned and performed all the experimental work. List of abbreviations and symbols,A Interfacial area.
AZC Ammonium zirconium carbonate,Average crack area. Concentration,CA Citric acid,CLA Cylindrical laboratory coater. CTMP Chemithermomechanical pulp,Diffusion coefficient. DiCA Contact angle of diiodomethane,DMA Dynamic mechanical analysis. DSC Differential scanning calorimetry,Elastic modulus.
Storage modulus,ESCA Electron spectroscopy for chemical analysis. EVOH Ethylene vinyl alcohol,Flux in x direction,Gly Glycerol. Gibbs free energy of mixing,Enthalpy of mixing,Boltzman constant. Crack length,Total measured length,MD Machine direction. Number of molecules,OTR Oxygen transmission rate,pph Parts per hundred.
Permeability,PA Polyamide,PE Polyethylene,PET Polyethylene terephthalate. PP Polypropylene,PVC Poly vinyl chloride,PVDC Poly vinylidene chloride. PEG Polyethylene glycol,PVOH Poly vinyl alcohol,RH Relative humidity. SEM Scanning electron microscope,Solubility coefficient. SP Starch to PVOH ratio,Entropy of mixing,Average thickness.
Absolute temperature,TMA Thermo mechanical analysis. Glass transition temperature,U Potential energy,Volume fraction. Average crack width,WCA Contact angle of water,WVTR Water vapour transmission rate. Average coat weight,XPS X ray photoelectron spectroscopy. Phase shift,Angular frequency,Total Surface Energy.
Lifshiz van der Waals component of the,surface energy. Electron donor component of the surface energy,Electron acceptor component of the surface. Table of Contents,Abstract I,List of papers included in the thesis III. Author s contribution IV,List of abbreviations and symbols V. 1 Objectives of the study 1,2 Background 2,Food packaging 2.
Polymeric materials as barrier materials 4,Barrier properties 6. Water resistance 7, Mechanical properties and the glass transition temperature 8. Plasticization 10,Polymer solutions and polymer blends 11. Adhesion 13,Coating 14,Converting 17,3 Materials 17. Poly vinyl alcohol 21,Polyethylene 23,Additives 24.
4 Experimental techniques 26,Coatings 26,Self supporting films 27. Extrusion 27,Oxygen transmission rate 28,Water vapour transmission rate 29. Mechanical properties of self supporting films 29,X Ray electron spectroscopy 31. Adhesion 33,Scanning electron microscopy SEM 34,Microscopic analysis 35. Contact angle determination 35,Surface roughness 36.
Surface profilometery 37,Creasing and folding 38,Stability in water of self supporting films 38. 5 Barrier Properties 39,6 Crosslinking 43,7 Mechanisms of failure 45. 8 Sustainability and socio economic aspects 46,9 Summary of papers 47. 10 Future perspectives 49,11 Conclusions 50,12 Acknowledgement 52. 13 References 54,1 Objectives of the study, Barrier coatings are normally applied on fibre based food packaging.
materials in order to shield the packaged food from gases liquids and. moisture The barrier coating materials currently being utilized for. food packaging are mostly oil based polymers but interest in. environment friendly bio based polymers has developed in recent. years due to the expanding interest in replacing oil based polymers. with them Currently bio based barrier materials have been surveyed. under conditions that are far from being realistic and there is thus a. need to centre research endeavours in this field, The main aim of this study was to gain detailed knowledge about bio. based barrier coatings and to explore the possibility of using them to. replace oil based polymers in food packaging The focus of this project. is to improve the mechanical properties barrier properties and. stability in water of starch based barrier layers The aim of the project. is also to understand the mechanism of failure of the layers during the. converting operations typically performed in industry to convert a. barrier coated board into a package, This work has explored how different plasticizers influence the. properties of starch based barrier layers with and without polyethylene. extrusion and how plasticizers affect the compatibility of starch PVOH. blends The way in which plasticizers affect the mechanical and barrier. properties of starch and starch PVOH coatings was also investigated. Furthermore a crack analysis of board coated with starch and starch. PVOH blends was performed after creasing and folding of the coated. board The purpose was to investigate how the flexibility of barrier. layers and baseboard properties can affect cracking in the layers after. creasing and folding of the coated board, Starch lignin based barrier coatings were also studied The major aim. being to improve the water stability of starch films by adding lignin to. starch films and further by cross linking the starch lignin coatings. Pilot trials were performed to investigate whether the good results. obtained in the laboratory could also be achieved on a pilot scale. 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

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