1. Noise evaluation of S-polymer gearsBoštjan Trobentar, Matija Hriberšek, Simon Kulovec, Srečko Glodež, Aleš Belšak, 2022, original scientific article Abstract: In this study, an acoustic behaviour of S-polymer gears made of the material combination
POM/PA66 was investigated and compared to the standardised involute gears (E-gears). Basic
evaluating characteristics included noise during operation, which is of particular significance when
noise reduction is expected. The measured signals were analysed in time and frequency domains
and the levels of acoustic activity were compared. The experimental results have shown that the
sound pressure level of both E- and S-polymer gears are proportional to the torque. However, the
comprehensive noise evaluation has shown some advantages of S-polymer gears if compared to the
E-polymer gears. In that respect, S-polymer gears were found more appropriate for noise reduction
of gear drive systems in the case of normal loading and typical drive speed. Future studies in the
operating behaviour of S-polymer gears could also cover noise evaluation using new methods of
sound signal analysis at different temperatures of gears.
Keywords: polymers, S-gears, sound, noise analysis
Published in DKUM: 24.03.2025; Views: 0; Downloads: 6
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2. 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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3. Durability and degradation of PVC-P roofing membrane—example of dynamic fatigue testingAndrej Ivanič, Samo Lubej, 2022, original scientific article Abstract: This paper presents a study of PVC-P waterproofing membrane Specimens. The Specimens
were taken from different segments of a flat roof after a service life of 11 years. The reason for
analysing the condition of the Specimens was the apparent degradation of the waterproofing, which
no longer guaranteed the watertightness of the roof. The analysis of the performance of the Specimens
was based on the control of the mechanical properties, which were compared with the declared
values. The mechanical properties of the degraded PVC-P waterproofing membranes with a polyester
mesh backing, which are prescribed by the standards, do not usually deviate from the declared
properties. This often poses a problem for liability and warranty claims due to the poor quality
of the waterproofing membrane. There may be several causes of degradation of PVC-P. For this
reason, in this paper, we present the possibility of controlling the properties of PVC-P waterproofing
membranes using cyclic dynamic fatigue, microstructure analysis using scanning electron microscopy
(SEM) and energy dispersive spectroscopy (EDS). The results show that the cause of the deterioration
of the PVC-P waterproofing membranes is often related to dehydrochlorination of the polymer.
However, the deterioration of the mechanical properties of the PVC-P waterproofing membranes can
be successfully demonstrated by cyclic dynamic fatigue.
Keywords: environmental impact of polymers, durability, polymer degradation
Published in DKUM: 13.03.2025; Views: 0; Downloads: 5
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4. 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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5. Effect of monomer type on the synthesis and properties of poly(ethylene furanoate)Johan Stanley, Zoi Terzopoulou, Panagiotis A. Klonos, Alexandra Zamboulis, Eleftheria Xanthopoulou, Savvas Koltsakidis, Dimitrios Tzetzis, Lidija Fras Zemljič, Dimitra A. Lambropoulou, Apostolos Kyritsis, George Z. Papageorgiou, Dimitrios Bikiaris, 2023, original scientific article Abstract: This work aimed to produce bio-based poly(ethylene furanoate) (PEF) with a high molecular weight using 2,5-furan dicarboxylic acid (FDCA) or its derivative dimethyl 2,5-furan dicarboxylate (DMFD), targeting food packaging applications. The effect of monomer type, molar ratios, catalyst, polycondensation time, and temperature on synthesized samples’ intrinsic viscosities and color intensity was evaluated. It was found that FDCA is more effective than DMFD in producing PEF with higher molecular weight. A sum of complementary techniques was employed to study the structure– properties relationships of the prepared PEF samples, both in amorphous and semicrystalline states. The amorphous samples exhibited an increase in glass transition temperature of 82–87 ◦C, and annealed samples displayed a decrease in crystallinity with increasing intrinsic viscosity, as analyzed by differential scanning calorimetry and X-ray diffraction. Dielectric spectroscopy showed moderate local and segmental dynamics and high ionic conductivity for the 2,5-FDCA-based samples. The spherulite size and nuclei density of samples improved with increased melt crystallization and viscosity, respectively. The hydrophilicity and oxygen permeability of the samples were reduced with increased rigidity and molecular weight. The nanoindentation test showed that the hardness and elastic modulus of amorphous and annealed samples is higher at low viscosities due to high intermolecular interactions and degree of crystallinity.
Keywords: bio-based polymers, poly(ethylene furanoate), polycondensation, thermal properties, mechanical properties, oxygen transmission rates
Published in DKUM: 13.02.2025; Views: 0; Downloads: 3
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7. Investigating the viability of epithelial cells on polymer based thin-filmsBoštjan Vihar, Jan Rožanc, Boštjan Krajnc, Lidija Gradišnik, Marko Milojević, Laura Činč Ćurić, Uroš Maver, 2021, original scientific article Abstract: The development of novel polymer-based materials opens up possibilities for several novel applications, such as advanced wound dressings, bioinks for 3D biofabrication, drug delivery systems, etc. The aim of this study was to evaluate the viability of vascular and intestinal epithelial cells on different polymers as a selection procedure for more advanced cell-polymer applications. In addition, possible correlations between increased cell viability and material properties were investigated. Twelve polymers were selected, and thin films were prepared by dissolution and spin coating on silicon wafers. The prepared thin films were structurally characterized by Fourier transform infrared spectroscopy, atomic force microscopy, and goniometry. Their biocompatibility was determined using two epithelial cell lines (human umbilical vein endothelial cells and human intestinal epithelial cells), assessing the metabolic activity, cell density, and morphology. The tested cell lines showed different preferences regarding the culture substrate. No clear correlation was found between viability and individual substrate characteristics, suggesting that complex synergistic effects may play an important role in substrate design. These results show that a systematic approach is required to compare the biocompatibility of simple cell culture substrates as well as more complex applications (e.g., bioinks).
Keywords: HUIEC, HUVEC, morphology, polymers, thin films, viability
Published in DKUM: 18.10.2024; Views: 0; Downloads: 1
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8. Hierarchically porous polyacetylene networks : adsorptive photocatalysts for efficient bisphenol a removal from waterDavid Šorm, Jiří Brus, Albin Pintar, Jan Sedláček, Sebastijan Kovačič, 2024, original scientific article Keywords: polyacetylenes, emulsion-templating, π-conjugated networks, macroporous polymers, heterogeneous photocatalysis
Published in DKUM: 29.08.2024; Views: 73; Downloads: 5
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9. Reinforcing ethyl cellulose aerogels with poly(lactic acid) for enhanced bone regenerationGabrijela Horvat, Jan Rožanc, Uroš Maver, Matjaž Finšgar, Željko Knez, Zoran Novak, 2024, original scientific article Abstract: Developing double porous biodegradable and biocompatible scafolds that can incorporate and release drugs in a controlled manner holds immense potential in regenerative medicine. This study presents a synthesis method for preparing a macro-mesoporous scafold, where poly(lactic acid) adds to the macroporous region and mechanical properties, and ethyl cellulose adds to the surface area (182 m2 /g). High surface area enables the incorporation of model drug indomethacin with an entrapment efciency of 17.0% and its later controlled release profle. The resulting scafold has desirable mechanical properties in the range of a natural trabecular bone with a compressive modulus of 22.4 MPa. The material is stable in the simulated body fuids for 120 days before the slow degradation starts. In vitro studies demonstrate the material’s ability to support bone cell adhesion, proliferation, and diferentiation, promoting osteogenic activity. Overall, the unique combination of poly(lactic acid) and ethyl cellulose produces advanced materials with tailored macro and mesopore properties, remarkable mechanical properties, optimal degradation rate, and drug delivery potential, making it a promising candidate for bone scafolds in regenerative medicine and tissue engineering
Keywords: bio composite, polymer-matrix composites (PMCs), polymers, porosity/voids, secondary ion mass spectrometry
Published in DKUM: 23.08.2024; Views: 130; Downloads: 9
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