Faculty of Technology and Metallurgy

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Author: search.filters.author.Bužarovska, AleksandraStart date: 2024

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    Thermoplastic Polyurethane/Polylactic Acid Blend Foams Loaded With <scp><i>Curcuma longa</i></scp> L. and <scp><i>Hypericum perforatum</i></scp> Extracts Towards Wound Dressing Applications
    (Wiley, 2025)
    Bužarovska, Aleksandra
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    Stanoeva, Jasmina Petreska
    ;
    Karamanolevski, Predrag
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    Popa, Andreea Daniela
    ;
    Dinescu, Sorina
    <jats:title>ABSTRACT</jats:title><jats:p>This study aimed to fabricate and evaluate TPU/polylactic acid foams loaded with natural extracts of <jats:styled-content style="fixed-case"> <jats:italic>Curcuma longa</jats:italic> </jats:styled-content> L. (C) and <jats:styled-content style="fixed-case"> <jats:italic>Hypericum perforatum</jats:italic> </jats:styled-content> (H) for WD application. In the frame of the structure/properties relationships study, different and complementary analyzes for WD materials, such as water contact angles measurements, water vapor transmission rate, water absorption, and extracts release studies were performed, in connection with the structural and thermal characterizations performed using scanning electron microscopy, differential scanning calorimetry and Fourier transform spectroscopy. The water absorption capacity of the blank blend foam and foams loaded with extracts (C and H) was found to be in the range of 8.31% ± 0.27, 90.7% ± 4.1 and 164% ± 4.0%, respectively. The loaded foams presented cumulative extracts release of 45.5% ± 2% (C) and 100% ± 1.1% (H) within 96 h and acceptable water vapor transmission rate in the range of 2088 ± 66 and 3520 ± 991 g·m<jats:sup>−2</jats:sup>·24 h<jats:sup>−1</jats:sup>, respectively. Summary, the investigated foams, enriched with both extracts, showed excellent performances in agreement with WD materials requirements, higher cell viability and proliferation compared to the reference foams, as well as non‐cytotoxic effects on human fibroblasts in experimental conditions.</jats:p>
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    Development of Poly(L-lactic acid) Films Containing Curcuma lunga L. Extract for Active Cheese Packaging
    (MDPI AG, 2025)
    Bužarovska, Aleksandra
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    Trajkovska Petkoska, Anka
    <jats:p>Biobased packaging solutions with active functions for different food categories are a very attractive topic nowadays. This packaging provides suitable preservation of the food quality and extends the shelf life of packed items. In addition, this is a promising pathway to overcome global pollution, to protect human health, as well as to provide a better planetary wellbeing. In this work, a packaging composition based on poly(lactic acid) (PLA) with the addition of Curcuma longa L. (C) extract prepared by the solution casting method is promoted as a potential packaging option for the active food packaging of cheese. The dopant levels of the extract were performed at 0.5%, 1%, 2%, 5%, and 10%, while the neat PLA film was used as a control. The obtained results are promising. By a thermal analysis, it is shown that C-extract has a plasticizing and nucleating effect on PLA molecules, as well as improving the barrier and other film properties. Moreover, this packaging was proven as a potential antimicrobial packaging for white cheese—it enables extending the shelf life by direct contact. This is a simple way of manufacturing biobased packaging doped with natural antimicrobials that could be used for other food categories that are prone to microbiological attack.</jats:p>
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    Piezoelectric PVDF‐TrFE nanocomposite mats filled with BaTiO<sub>3</sub> nanofibers: The effect of poling conditions
    (Wiley, 2024-02)
    Stojchevska, Ema
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    Zanoni, Michele
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    Gasperini, Leonardo
    ;
    Selleri, Giacomo
    <jats:title>Abstract</jats:title><jats:p>BaTiO<jats:sub>3</jats:sub> nanofibers (BT NFs), prepared by electrospinning, were used as a filler for electrospun poly(vinylidene fluoride‐<jats:italic>co</jats:italic>‐trifluoroethylene) (PVDF‐TrFE) nanocomposite mats. The phase structure and the effect of poling conditions on the piezoelectric properties of PVDF‐TrFE/BT nanocomposites were investigated. The results showed an improved degree of crystallinity (78.6%) and a high <jats:italic>β</jats:italic>‐crystal phase (up to 98.3%) in all electrospun samples, independent of the nanofiber content. The two‐step poling method, applying electric fields of opposite polarity, led to significantly improved piezoelectric constants d<jats:sub>33</jats:sub> (−31.7 pC N<jats:sup>−1</jats:sup>), strongly dependent on the added BaTiO<jats:sub>3</jats:sub> nanofibers. The inclusion of piezoelectric ceramic nanofibers into a polymer matrix, easily carried out by means of electrospinning, followed by an ad hoc optimized poling treatment, allowed to develop flexible materials with enhanced piezoelectric properties, potentially exploitable in innovative conversion systems used in wearable and sensing devices.</jats:p>