1. Keratinski nanodelci iz produkta hidrotermične razgradnje perja/volne in formulacija premazov na celulozne tekstilije : magistrsko deloTamara Gavrić, 2025, master's thesis Abstract: V magisterskem delu je predstavljena sinteza delcev iz ekstrahiranega keratina iz odpadne volne oz. perja in kvaterniziranega hitozana. Cilj je, da dobimo nanodelce (velikost delcev do 100 nm), katere bi uporabili za medicinske tekstilije namenjene celjenju ran. Keratinske suspenzije smo še dodatno prečistili z dializo in filtrirali skozi 1 μm filter. Sintezo nanodelcev smo izvedli z metodo ionskega geliranja, kjer smo počasi dodajali hitozan v keratin pri pH=5, konstantnem mešanju in pri sobni tempraturi z namenom, da bi zamrežili keratinske karboksilne (negativne) skupine s hitozanskimi aminskimi (pozitivnimi) skupinami. Pri optimizaciji razmerij in sprotnem merjenju zeta potenciala je bila izbrana mešanica F v množinskem razmerju hitozan:keratin=1:5000. Ta je pri meritvah zeta potenciala skozi pH območje med 2 in 9, imela izoelektrično točko pri pH okoli 7 in s tem obdržala tako pozitiven kot negativen značaj, kar kaže na amfoterni značaj in uspešno zamreženje. S tem v delce doprinesemo antioksidativne kot protimikrobne značilnosti obeh združenih polimerov. Optimalni mešanici smo nanesli na bombažno tekstilijo in preverili antioksidativnost le te, ki je bila visoka. Nazadnje smo naredili test omočljivost tekstilije in izmerili ATR-FTIR spekter, s pomočjo katerega smo ugotovili, da pri sintezi premaza in premazovanju ni prišlo do spremembe glavnih funkcionalnih skupin,
Keywords: ionsko geliranje, keratin, hitozan, nanodelci, celjenje ran, antioksidativnost
Published in DKUM: 02.04.2025; Views: 0; Downloads: 15
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2. Faculty of Mechanical Engineering : Research Guide2025, guide book Abstract: The publication presents an overview of research activities and research achievements at the Faculty of Mechanical Engineering. The following research areas are presented: Energy, process and environmental engineering, Construction and design, Materials technology, Mechanics, Production engineering, Textile materials and design, and Fundamental and general areas. Individual laboratories and centers of the faculty present their research equipment, service offerings for industry, collaborations with companies and other institutions, the most prominent publications, patents, national and international projects and the most important research achievements.
Keywords: energy, construction and design, process and environmental engineering, materials technology, mechanics, production engineering, textile materials and design
Published in DKUM: 01.04.2025; Views: 0; Downloads: 2
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3. Significant fragmentation of disposable surgical masks—enormous source for problematic micro/nanoplastics pollution in the environmentAlen Erjavec, Olivija Plohl, Lidija Fras Zemljič, Julija Volmajer Valh, 2022, original scientific article Abstract: The pandemic of COVID-19 disease has brought many challenges in the field of personal
protective equipment. The amount of disposable surgical masks (DSMs) consumed increased dramatically, and much of it was improperly disposed of, i.e., it entered the environment. For this reason,
it is crucial to accurately analyze the waste and identify all the hazards it poses. Therefore, in the
present work, a DSM was disassembled, and gravimetric analysis of representative DSM waste was
performed, along with detailed infrared spectroscopy of the individual parts and in-depth analysis
of the waste. Due to the potential water contamination by micro/nanoplastics and also by other
harmful components of DSMs generated during the leaching and photodegradation process, the
xenon test and toxicity characteristic leaching procedure were used to analyze and evaluate the
leaching of micro/nanoplastics. Micro/nanoplastic particles were leached from all five components
of the mask in an aqueous medium. Exposed to natural conditions, a DSM loses up to 30% of its mass
in just 1 month, while micro/nanoplastic particles are formed by the process of photodegradation.
Improperly treated DSMs pose a potential hazardous risk to the environment due to the release of
micro/nanoparticles and chloride ion content.
Keywords: DSM, micro/nanoparticles, leaching, artificial weathering, environmental pollution
Published in DKUM: 26.03.2025; Views: 0; Downloads: 1
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4. Obtaining medical textiles based on viscose and chitosan/zinc nanoparticles with improved antibacterial properties by using a dielectric barrier dischargeMatea Korica, Ana Kramar, Zdenka Peršin Fratnik, Bratislav M. Obradović, Milorad Kuraica, Biljana Dojčinović, Lidija Fras Zemljič, Mirjana M. Kostić, 2022, original scientific article Abstract: This study aimed to obtain functional viscose textiles based on chitosan coatings with
improved antibacterial properties and washing durability. For that reason, before functionalization
with chitosan/zinc nanoparticles (NCH+Zn), the viscose fabric was modified by nonthermal gas
plasma of dielectric barrier discharge (DBD) to introduce into its structure functional groups suitable
for attachment of NCH+Zn. NCH+Zn were characterized by measurements of hydrodynamic diameter and zeta potential and AFM. DBD-plasma-modified and NCH+Zn-functionalized fabrics were
characterized by zeta potential measurements, ATR-FTIR spectroscopy, the calcium acetate method
(determination of content of carboxyl and aldehyde groups), SEM, breaking-strength measurements,
elemental analysis, and ICP-OES. Their antibacterial activity was determined under dynamic contact
conditions. In addition to SEM, the NCH+Zn distributions on viscose fabrics were also indirectly characterized by measuring their absorbent capacities before and after functionalization with NCH+Zn.
Washing durability was monitored through changes in the zeta potential, chitosan and zinc content,
and antibacterial activity after 1, 3, and 5 washing cycles. The obtained results showed that DBD
plasma modification contributed to the simultaneous improvement of NCH+Zn sorption and antibacterial properties of the viscose fabric functionalized with NCH+Zn, and its washing durability,
making it suitable for the production of high-value-added medical textiles.
Keywords: medical textiles, antibacterial properties, viscose, chitosan/zinc nanoparticles, dielectric barrier discharge
Published in DKUM: 26.03.2025; Views: 0; Downloads: 2
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5. First insights into the antiviral activity of chitosan-based bioactive polymers towards the bacteriophage Phi6: physicochemical characterization, inactivation potential, and inhibitory mechanismsOlivija Plohl, Katja Fric, Arijana Filipić, Polona Kogovšek, Magda Tušek-Žnidarič, Lidija Fras Zemljič, 2022, original scientific article Abstract: The outbreak of the worrisome coronavirus disease in 2019 has caused great concern
among the global public, especially regarding the need for personal protective equipment with
applied antiviral agents to reduce the spread and transmission of the virus. Thus, in our research,
chitosan-based bioactive polymers as potential antiviral agents were first evaluated as colloidal
macromolecular solutions by elemental analysis and charge. Three different types of low and high
molecular weight chitosan (LMW Ch, HMW Ch) and a LMW Ch derivative, i.e., quaternary chitosan
(quart-LMW Ch), were used. To explore their antiviral activity for subsequent use in the form of
coatings, the macromolecular Chs dispersions were incubated with the model virus phi6 (surrogate
for SARS-CoV-2), and the success of virus inactivation was determined. Inactivation of phi6 with
some chitosan-based compounds was very successful (>6 log), and the mechanisms behind this
were explored. The changes in viral morphology after incubation were observed and the changes in
infrared bands position were determined. In addition, dynamic and electrophoretic light scattering
studies were performed to better understand the interaction between Chs and phi6. The results
allowed us to better understand the antiviral mode of action of Chs agents as a function of their
physicochemical properties.
Keywords: bacteriophage phi6, bioactive polysaccharide biomaterials, chitosans, antiviral activity, dynamic and electrokinetic light scattering, charge, biointerfaces
Published in DKUM: 26.03.2025; Views: 0; Downloads: 1
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6. 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, original scientific article Abstract: 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.
Keywords: chitosan, active packaging, PET, recycling, reusability
Published in DKUM: 26.03.2025; Views: 0; Downloads: 5
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7. Unlocking innovation: Novel films synthesised and structurally analysed from poly (l-lactide-co-ethylene adipate) block copolymers blended with poly(lactic acid)Athira John, Klementina Pušnik Črešnar, Johan Stanley, Sabina Vohl, Damjan Makuc, Dimitrios Bikiaris, Lidija Fras Zemljič, 2025, original scientific article Abstract: This study addresses the inherent shortcomings of poly (lactic acid) (PLA), a biodegradable polymer widely used in industries such as packaging and biomedical applications. The principal challenge of PLA resides in its low crystallinity, which detrimentally affects its mechanical properties and thermal stability. Additionally, PLA is prone to water and hydrolysis, which compromises its chemical resistance and can lead to degradation over time. To overcome surmount these limitations, the study focuses on the development of hybrid films through the blending of PLA with poly (l-lactide-co-ethylene adipate) (pLEA) block copolymers. The objective is to augment the crystallinity, mechanical performance, and chemical resistance of the resulting materials. The study employs a range of analytical techniques, including Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Polarised Light Microscopy (PLM), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA), to thoroughly characterize the copolymers and blend films. By systematically selecting blending ratios and processing methodologies, the study demonstrates enhancements in the properties of the resultant hybrid films compared to neat PLA. Specifically, the structure of films significantly changed from amorphous to crystalline in a short duration - 5 min, of annealing., leading to better tensile strength, modulus and reduced wettability, which are crucial for applications requiring durability and resistance to environmental factors. Films made from 30 wt% of pLEA 97.5/2.5 with 70 % of PLA by fast cooling exhibited outstanding mechanical properties, with a tensile strength 20 MPa higher than that of neat PLA films. Additionally, the chemical resistance may be improved, as evidenced by a decrease in wettability by approximately 15° and a reduction in the polar component of the surface free energy by about 7 mN/m. Hydrophobic, water-repellent materials resist penetration by water and other polar solvents, reducing exposure to corrosive substances and enhancing chemical resistance through barrier protection. Overall, this research addresses the limitations of PLA through innovative copolymerization and blending strategies, offering valuable insights into optimizing the material's properties for various practical applications.
Keywords: Poly(lactic acid), Poly(l-lactide-co-ethylene adipate), copolymer, blend, crystallinity
Published in DKUM: 13.03.2025; Views: 0; Downloads: 7
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8. Thermal, molecular dynamics, and mechanical properties of poly(ethylene furanoate)/poly(ε-caprolactone) block copolymersJohan Stanley, Panagiotis A. Klonos, Aikaterini Teknetzi, Nikolaos Rekounas, Apostolos Kyritsis, Lidija Fras Zemljič, Dimitra A. Lambropoulou, Dimitrios Bikiaris, 2024, original scientific article Abstract: This study presents the synthesis and characterization of a series of multiblock copolymers, poly(ethylene 2,5-furandicarboxylate)-poly(ε-caprolactone) (PEF-PCL), created through a combination of the two-step melt polycondensation method and ring opening polymerization, as sustainable alternatives to fossil-based plastics. The structural confirmation of these block copolymers was achieved through Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), ensuring the successful integration of PEF and PCL segments. X-ray Photoelectron Spectroscopy (XPS) was employed for chemical bonding and quantitative analysis, providing insights into the distribution and compatibility of the copolymer components. Differential Scanning Calorimetry (DSC) analysis revealed a single glass transition temperature (Tg), indicating the effective plasticizing effect of PCL on PEF, which enhances the flexibility of the copolymers. X-ray Diffraction (XRD) studies highlight the complex relationship between PCL content and crystallization in PEF-PCL block copolymers, emphasizing the need to balance crystallinity and mechanical properties for optimal material performance. Broadband Dielectric Spectroscopy (BDS) confirmed excellent distribution of PEF-PCL without phase separation, which is vital for maintaining consistent material properties. Mechanical properties were evaluated using Nanoindentation testing, demonstrating the potential of these copolymers as flexible packaging materials due to their enhanced mechanical strength and flexibility. The study concludes that PEF-PCL block copolymers are promising candidates for sustainable packaging solutions, combining environmental benefits with desirable material properties.
Keywords: poly(ethylene furanoate), poly(ε-caprolactone), block copolymers, thermal properties, molecular dynamics, crystallinity, mechanical properties, flexible packaging
Published in DKUM: 13.03.2025; Views: 0; Downloads: 5
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9. Thermal decomposition kinetics and mechanism of poly(ethylene 2,5-furan dicarboxylate) Nanocomposites for food packaging applicationsJohan Stanley, Evangelia Tarani, Nina Maria Ainali, Tjaša Kraševac Glaser, Lidija Fras Zemljič, Konstantinos Chrissafis, Dimitra A. Lambropoulou, Dimitrios Bikiaris, 2024, original scientific article Abstract: Poly(ethylene 2,5-furan dicarboxylate) (PEF) based nanocomposites containing different nanoparticles like Ag, TiO2, ZnO, ZrO2 Ce-Bioglass, have been synthesized via in-situ polymerization techniques targeting food pack aging applications. Zeta potential measurements showed an increase in the negative zeta potential value due to an increase in the surface charge density of the nanocomposites. Thermogravimetric analysis results proved that, except PEF-ZnO nanocomposite, all the other nanocomposites exhibited good resistance to thermal degradation without serious mass loss until 330 ◦C. Thermal decomposition kinetic analysis and the dependence of activation energy on the degree of conversion (α), indicated that the presence of ZnO nanoparticles influences, the degradation mechanism of PEF. In contrast, the presence of Ce-Bioglass nanoparticles leads to a slower degra dation process, contributing to the enhanced resistance to thermal degradation of the PEF-Bioglass nano composite. The thermal degradation mechanism of PEF nanocomposites analyzed by pyrolysis‒gas chromatography/mass spectrometry (Py-GC/MS) indicated that the primary thermal degradation mechanism for the studied nanocomposites was β-hydrogen bond scission, while to a lesser extent, α-hydrogen bond scission products were noted in PEF-TiO2 and PEF-ZrO2 nanocomposites.
Keywords: bio based polymers, Poly(ethylene 2, 5-furan dicarboxylate), nanoparticles, thermal properties, nanocomposites, decomposition mechanism
Published in DKUM: 13.03.2025; Views: 0; Downloads: 4
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10. Study on impact of monomers towards high molecular weight bio-based poly(ethylene furanoate) via solid state polymerization techniqueJohan Stanley, Eleftheria Xanthopoulou, Margaritis Kostoglou, Lidija Fras Zemljič, Dimitra A. Lambropoulou, Dimitrios Bikiaris, 2024, original scientific article Abstract: In recent years, bio-based poly(ethylene furanoate) has gained the attention of packaging industries owing to its remarkable properties as a promising alternative to fossil-based polymers. It is necessary to synthesize high-molecular-weight polymers using effective and straightforward techniques for their commercialization. In this present work, poly(ethylene 2,5-furan dicarboxylate) (PEF) was produced with a high molecular weight of 0.43 dL/g using 2,5-furan dicarboxylic acid (FDCA) or its derivative Dimethyl-2,5-Furan dicarboxylate (DMFD), followed by solid-state polymerization (SSP) conducted at different temperatures and reaction times. The intrinsic viscosity ([η]), carboxyl end-group concentration (–COOH), and thermal properties of the produced polyesters were evaluated using differential scanning calorimetry (DSC). The results indicated that the SSP process improved the melting temperature and crystallinity of both the PEF samples as the reaction times and temperatures increased, as corroborated by DSC and X-ray diffraction (XRD) analyses. Additionally, both intrinsic viscosity and number-average molecular weight saw an increase with longer SSP durations and higher temperatures, while the concentration of carboxyl end groups decreased, aligning with expectations. The overall results indicate that PEF (DMFD) samples exhibited a significant increase in crystallization and molecular weight, attributed to their lower degree of crystallinity and their monomer’s high purity.
Keywords: bio-based polymers, 2, 5-furan dicarboxylic acid, dimethyl 2, 5-furan dicarboxylate, poly(ethylene 2, 5-furan dicarboxylate), poly(ethylene furanoate), solid state polymerization, thermal properties
Published in DKUM: 10.03.2025; Views: 0; Downloads: 6
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