1. Economical chemical recycling of complex PET waste in the form of active packaging materialJulija Volmajer Valh, Dimitrije Stopar, Ignacio Selaya Berodia, Alen Erjavec, Olivera Šauperl, Lidija Fras Zemljič, 2022, izvirni znanstveni članek Opis: Since millions of tons of packaging material cannot be recycled in conventional ways, most
of it ends up in landfills or even dumped into the natural environment. The researched methods
of chemical depolymerization therefore open a new perspective for the recycling of various PET
materials, which are especially important for packaging. Food preservative packaging materials
made from PET plastics are complex, and their wastes are often contaminated, so there are no
sophisticated solutions for them in the recycling industry. After integrating the biopolymer chitosan,
which is derived from natural chitin, as an active surface additive in PET materials, we discovered
that it not only enriches the packaging material as a microbial inhibitor to reduce the bacteria
Staphylococcus aureus and Escherichia coli, thus extending the shelf life of the contained food, but also
enables economical chemical recycling by alkaline or neutral hydrolysis, which is an environmentally
friendly process. Alkaline hydrolysis at a high temperature and pressure completely depolymerizes
chitosan-coated PET packaging materials into pure terephthalic acid and charcoal. The products
were characterized by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance
spectroscopy, and elemental analysis. The resulting reusable material represents raw materials
in chemical, plastic, textile, and other industries, in addition to the antimicrobial function and
recyclability itself.
Ključne besede: chitosan, active packaging, PET, recycling, reusability
Objavljeno v DKUM: 26.03.2025; Ogledov: 0; Prenosov: 5
 Celotno besedilo (3,56 MB)
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2. Exploring chitosan-plant extract bilayer coatings: Advancements in active food packaging via polypropylene modificationSaša Kaloper, Olivija Plohl, Sonja Smole Možina, Alenka Vesel, Vida Šimat, Lidija Fras Zemljič, 2024, izvirni znanstveni članek Opis: UV-ozone activated polypropylene (PP) food films were subjected to a novel bilayer coating process involving primary or quaternary chitosan (CH/QCH) as the first layer and natural extracts from juniper needles (Juniperus oxycedrus; JUN) or blackberry leaves (Rubus fruticosus; BBL) as the second layer. This innovative approach aims to redefine active packaging (AP) development. Through a detailed analysis by surface characterization and bioactivity assessments (i.e., antioxidant and antimicrobial functionalities), we evaluated different coating combinations. Furthermore, we investigated the stability and barrier characteristics inherent in these coatings. The confirmed deposition, coupled with a comprehensive characterization of their composition and morphology, underscored the efficacy of the coatings. Our investigation included wettability assessment via contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), which revealed substantial enhancements in surface concentrations of elements and functional groups of CH, QCH, JUN, and BBL. Scanning electron microscopy (SEM) unveiled the coatings' heterogeneity, while time-of-flight secondary ion mass spectrometry (ToF-SIMS) and CA profiling showed moderately compact bilayers on PP, providing active species on the hydrophilic surface, respectively. The coatings significantly reduced the oxygen permeability. Additionally, single-layer depositions of CH and QCH remained below the overall migration limit (OML). Remarkably, the coatings exhibited robust antioxidative properties due to plant extracts and exceptional antimicrobial activity against S. aureus, attributed to QCH. These findings underscore the pivotal role of film surface properties in governing bioactive characteristics and offer a promising pathway for enhancing food packaging functionality.
Ključne besede: chitosan, plant extracts, polypropylene, active packaging, surface characterization, bioactivity
Objavljeno v DKUM: 27.05.2024; Ogledov: 241; Prenosov: 21
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4. Active agents incorporated in polymeric substrates to enhance antibacterial and antioxidant properties in food packaging applicationsJohan Stanley, Athira John, Klementina Pušnik Črešnar, Lidija Fras Zemljič, Dimitra A. Lambropoulou, Dimitrios Bikiaris, 2023, pregledni znanstveni članek Ključne besede: food packaging, active agents, bulk preparation techniques, antibacterial and antioxidant properties
Objavljeno v DKUM: 11.04.2024; Ogledov: 251; Prenosov: 26
Celotno besedilo (5,51 MB)
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