1. Unraveling the antibiofilm activity of a new nanogold resin for dentures and epithesisVera Ivanović, Danica Popović Antić, Sanja Petrović, Rebeka Rudolf, Peter Majerič, Miloš Lazarević, Igor Djordjević, Vojkan Lazić, Milena Radunović, 2022, izvirni znanstveni članek Opis: Dentures and epitheses are mostly made from poly(methyl methacrylate) (PMMA), which
does not show antimicrobial properties. They present reservoirs of microorganisms grown in
biofilms. The aim of this study is to prepare a PMMA enriched with gold nanoparticles (AuNPs)-
PMMA/AuNPs and the examination of its physical, mechanical and antimicrobial properties. The
AuNPS were synthetized from HAuCl4 using the ultrasonic spray pyrolysis method with lyophilization. The PMMA/AuNP samples were compared to PMMA samples. Density was measured by
pycnometer. Microhardness was evaluated using the Vickers hardness test. Monomicrobial biofilm
formation (Streptococcus mitis, Candida albicans, Staphylococcus aureus and Escherichia coli) was measured by colony-forming units (CFUs) and MTT test and visualized by SEM. AuNP release was
measured indirectly (the CFUs of the medium around the sample). The density and microhardness
of the PMMA/AuNPs were similar to those of the PMMA. CFU and MTT values for the biofilms
formed on the PMMA for each of the tested species were higher than those of the biofilms formed on
the PMMA/AuNPs. The CFUs of the medium around the sample were similar for both materials.
PMMA/AuNPs showed a significant reduction in the monomicrobial biofilms of all tested species.
AuNPs are not released from PMMA/AuNPs. Density, indirect measurement of residual monomer
and dentures weight were similar between PMMA and PMMA/AuNPs. Microhardness, as a measure
of the wear resistance, was also similar between tested discs.
Ključne besede: PMMA, gold nanoparticles (AuNPs), biofilm, antibiofilm effect
Objavljeno v DKUM: 24.03.2025; Ogledov: 0; Prenosov: 2
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2. Vpliv parametrov procesa brizganja na zaostale napetosti in nastanek razpok pri več-komponentnih prozornih izdelkih iz pmma : diplomsko deloKatja Jernejšek, 2022, diplomsko delo Opis: Pokrove za zadnje avtomobilske luči izdelamo z brizganjem plastičnih mas. Kakovost izdelkov nadzorujemo in zagotavljamo s spreminjanjem procesnih parametrov. Velik vpliv na spreminjanje kakovosti izdelkov med uporabo imajo zaostale napetosti, ki se pojavijo med njihovim ohlajanjem. Pomembno je, da visoke zaostale napetosti na izdelkih pravočasno odkrijemo, sicer se lahko zaradi njih, v času uporabe izdelka, na izdelkih pojavijo razpoke.
Pri izvedbi eksperimenta nas je zanimalo, kako se s spreminjanjem procesnih parametrov spreminja nastanek razpok na izdelkih. Pokrove smo izpostavili tekočemu etanolu in pregledovali nastale razpoke. Nastanek razpok na pokrovih smo preprečili z brizganjem pri nižjem naknadnem tlaku in krajšem času delovanja naknadnega tlaka.
Ključne besede: PMMA, plastične mase, brizganje plastičnih mas, zaostale napetosti, nastanek razpok
Objavljeno v DKUM: 05.03.2024; Ogledov: 318; Prenosov: 6
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3. Synthesis of PMMA/ZnO nanoparticles composite used for resin teethDanica Popović Antić, Rajko Bobovnik, Silvester Bolka, Miroslav Vukadinovič, Vojkan Lazić, Rebeka Rudolf, 2017, izvirni znanstveni članek Opis: Wear resistance is one of the most important physical properties of the artificial teeth used in acrylic dentures. The goal of this research was to synthesize a new composite material made of matrix Poly-(methyl methacrylate)-PMMA with different percentages (2 % and 3 % of volume fractions) of zinc-oxide nanoparticles (ZnO NPs) as reinforcing elements, to improve its mechanical properties. The dynamic mechanical behaviour of this composite was studied through the DMA method in comparison to the pure PMMA supported by the characterization of their microstructures. Then the wear resistance was analysed on the samples, which were prepared in the form of teeth. In this context their vertical height loss was measured after 100,000 chewing cycles on a chewing simulator, before and after the artificial thermal ageing. Investigations showed that the PMMA/ZnO NP composites dampened the vibrations better than the pure PMMA, which could be assigned to the homogenous distribution of ZnO NPs in the PMMA matrix. It was found that the mean vertical height loss for the pure PMMA teeth was significantly higher (more than 4 times) compared to composite teeth made with ZnO NPs. Introducing the thermal artificial ageing led to the finding that there was no effect on the height loss by the composite material with 3 % of volume fractions of ZnO NPs. Based on this it was concluded that PMMA/ZnO NPs composites showed improved in-vitro wear resistance compared to acrylic-resin denture teeth, so this new composite material should be preferred when occlusal stability is considered to be of high priority.
Ključne besede: poly-methyl methacrylate, PMMA, zinc-oxide nanoparticles, composite, resin teeth
Objavljeno v DKUM: 12.12.2017; Ogledov: 1876; Prenosov: 446
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4. Monolithic magneto-optical nanocomposites of barium hexaferrite platelets in PMMAGregor Ferk, Peter Krajnc, Anton Hamler, Alenka Mertelj, Federico Cebollada, Mihael Drofenik, Darja Lisjak, 2015, izvirni znanstveni članek Opis: The incorporation of magnetic barium hexaferrite nanoparticles in a transparent polymer matrix of poly(methyl methacrylate) (PMMA) is reported for the first time. The barium hexaferrite nanoplatelets doped with Sc3+, i.e., BaSc0.5Fe11.5O12 (BaHF), having diameters in the range 20 to 130 nm and thicknesses of approximately 5 nm, are synthesized hydrothermally and stabilized in 1-butanol with dodecylbenzenesulfonic acid. This method enables the preparation of monolithic nanocomposites by admixing the BaHF suspension into a liquid monomer, followed by in-situ, bulk free-radical polymerization. The PMMA retains its transparency for loadings of BaHF nanoparticles up to 0.27 wt.%, meaning that magnetically and optically anisotropic, monolithic nanocomposites can be synthesized when the polymerization is carried out in a magnetic field. The excellent dispersion of the magnetic nanoparticles, coupled with a reasonable control over the magnetic properties achieved in this investigation, is encouraging for the magneto-optical applications of these materials.
Ključne besede: polymer composites, nanoparticles, polymethyl methacrylate, PMMA
Objavljeno v DKUM: 23.06.2017; Ogledov: 1638; Prenosov: 450
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5. Raziskave formiranja asimetričnih poroznih membran v ternarnem sistemu poli(metilmetakrilat)/N,N-dimetilformamid/voda (PMMA/DMF/voda) : diplomsko deloIris Gnjidič, 2001, diplomsko delo Ključne besede: organska kemija, membrane, polimetilmetakrilat, PMMA, dimetilformamid, DMF, mokra fazna separacija, asimetrične porozne membrane
Objavljeno v DKUM: 26.07.2007; Ogledov: 3597; Prenosov: 0 |
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