Water Vapor Barrier Studies Of Cellophane Films
Rantanen, Topias (2024)
2024
Materiaalitekniikan DI-ohjelma - Master's Programme in Materials Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2024-09-30
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202409088590
https://urn.fi/URN:NBN:fi:tuni-202409088590
Tiivistelmä
Sustainable and biodegradable food packaging films are a popular topic of research due to the large amounts of plastics being produced each year. Cellophane films are made from naturally occurring cellulose, which makes it a tempting option for packaging materials. However, cellophane films are limited in their use by their poor water vapor barrier. In this thesis coating layers are used to improve the water vapor barrier of cellophane.
Water vapor barrier properties of cellophane films were improved by coating it with AKD, carnauba and their layer combinations. Hydrophobized cellulose nanocrystals (HmCNC) were also incorporated into the carnauba matrix in concentrations of 5-, 10- and 20% per carnauba’s weight. Films with an even thickness and some haze were successfully created. Water vapor barrier levels in the same order of magnitude as PE and PET could be achieved, thus proving carnauba coatings with HmCNCs as a promising set of coating materials. The produced films were estimated to be biodegradable and sustainable.
Films were also measured and inspected for their oxygen transmission rates (OTR), grease barriers and pinholes. Cross-section images were taken of the films to evaluate the coating layer’s quality. Their coating grammage was measured for normalizing the transmission rate results.
Hydrophobized nanoparticles were created by grafting of lactic acid onto cellulose nano-crystals. Efforts at further grafting fatty acids on the lactic acid chain were not successful. The nanoparticles were characterized by using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, differential calorimetry, and thermogravimetric analysis.
Suspensions of carnauba were made by heating and sonication in water with and without surfactants. Suspension with surfactant was then dried and the collected wax particles redispersed in ethanol to gain a higher concentration wax suspension.
Water vapor barrier properties of cellophane films were improved by coating it with AKD, carnauba and their layer combinations. Hydrophobized cellulose nanocrystals (HmCNC) were also incorporated into the carnauba matrix in concentrations of 5-, 10- and 20% per carnauba’s weight. Films with an even thickness and some haze were successfully created. Water vapor barrier levels in the same order of magnitude as PE and PET could be achieved, thus proving carnauba coatings with HmCNCs as a promising set of coating materials. The produced films were estimated to be biodegradable and sustainable.
Films were also measured and inspected for their oxygen transmission rates (OTR), grease barriers and pinholes. Cross-section images were taken of the films to evaluate the coating layer’s quality. Their coating grammage was measured for normalizing the transmission rate results.
Hydrophobized nanoparticles were created by grafting of lactic acid onto cellulose nano-crystals. Efforts at further grafting fatty acids on the lactic acid chain were not successful. The nanoparticles were characterized by using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, differential calorimetry, and thermogravimetric analysis.
Suspensions of carnauba were made by heating and sonication in water with and without surfactants. Suspension with surfactant was then dried and the collected wax particles redispersed in ethanol to gain a higher concentration wax suspension.