Adrian Catalin Taut

This study focuses on the development of bioactive packaging materials by incorporating grape pomace and copper particles into polylactic acid (PLA) composites. The goal is to increase the shelf life of packaged foods while benefiting the health of consumers through the use of these active materials. 6 recipes of composite materials based on polylactic acid and Proviplast 2624 plasticizer were obtained. The additives added were: grape pomace, added at 0.5%, 1% and 1.5%, and copper particles, formed using PEG 600 + CuSO₄, added at 2%, 5% and 8%. Material characterization techniques: FTIR Spectroscopy, used to study the chemical structure. Differential scanning calorimetry (DSC): examined thermal transitions such as glass transition and melting temperatures. Thermogravimetric analysis (TGA) and differential thermogravimetry (DTG): evaluated thermal stability and degradation temperatures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM): analyzed the surface morphology and structure. Mechanical tests: evaluated tensile strength, elongation at break and flexibility. Thermal property analyzes revealed that the additives acted as plasticizers, reducing the intermolecular forces between PLA chains, which decreased the glass transition temperature (Tg), cold crystallization temperature (Tcc) and melting temperature (Tm). The addition of grape pomace and copper particles decreased the degradation temperature of PLA composites, indicating a slight reduction in thermal stability. The transformation temperatures changed and the nature of the thermal transitions (exothermic or endothermic) varied with additive concentrations. Mechanical properties indicated a reduction in tensile strength with increasing additive concentration. Elongation at break and longitudinal modulus of elasticity increased significantly, especially with grape pomace, improving the flexibility of PLA. These changes indicate that the material can absorb more energy before breaking, making it more ductile and more suitable for flexible packaging applications. Increased flexibility and improved thermal resistance ensure that these materials can withstand the demands of packaging, handling and shipping. The combination of improved flexibility, thermal resistance and moderate tensile strength makes these PLA-based composites incorporated with grape pomace or copper particles, enhance the aspect of sustainability by recycling agricultural waste, making the material both ecological and functional, making it a viable option for active food packaging.

This article proposes the synthesis and characterization of (triethylene glycol dimethacrylate–N,N-dihydroxyethyl-p-toluidine) TEGDMA-DHEPT self-healing microcapsules for their inclusion in dental composite formulations. The obtaining method is the in situ emulsion polymerization of the (poly urea-formaldehyde) (PUF) coatings. The microcapsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), high-performance liquid chromatography (HPLC), and low-field nuclear magnetic resonance (NMR) techniques. The optimal formation of uniform microcapsules is achieved at a stirring speed of 800 rpm and centrifugation is no longer necessary. HPLC demonstrates that the microcapsules formed at 800 rpm show a better control of liquid release than the heterogeneous ones obtained at a lower stirring speed. The centrifuged samples have rounded shapes, with dimensions between 80 and 800 nm, while the non-centrifuged samples are more uniform, with a spherical shape and dimensions of approximately 800 nm.

Several forged 3-Polker coins have been reported in historical sources on the financial crisis that occurred between 1619 and 1623 at the start of the 30-year-long war. Supposedly, belligerent countries forged other countries’ coins which were then used for external payments as a war strategy. Thus, a lot of 3-Polker coins (e.g., Sigismund-III-type) were forged, and the markets became flooded with poor currency. In the present day, these pre-modern forgeries are rare archeological findings. Only five forged 3-Polker coins randomly found in Transylvania were available for the current study. There are deeper implications of silver and tin in the forgery techniques that need to be considered. Thus, the forged 3-Polker coins were investigated via nondestructive methods: SEM microscopy coupled with EDS elemental spectroscopy for complex microstructural characterization and XRD for phase identification. Three distinct types of forgery methods were identified: the amalgam method is the first used for copper blank silvering (1620), and immersion in melted silver (1621) is the second one. Both methods were used to forge coins with proper legends and inscriptions. The third method is the tin plating of copper coins (with corrupted legend and altered design) (1622, 1623, and 1624). The EDS investigation revealed Hg traces inside the compact silver crusts for the first type and the elongated silver crystallites in the immersion direction, which are well-attached to the copper core for the second type. The third forgery type has a rich tin plating with the superficial formation of Cu₆Sn₅ compound that assures a good resistance of the coating layer. Therefore, this type should have been easily recognized as fake by traders, while the first two types require proper weighing and margin clipping to ensure their quality.

The present study is focused on polylactic acid (PLA) blending with bio nanoadditives, such as Tonsil^® (clay) and Aerosil^®, to obtain nanocomposites for a new generation of food packaging. The basic composition was enhanced using Sorbitan oleate (E494) and Proviplast as plasticizers, increasing the composite samples’ stability and their mechanical strength. Four mixtures were prepared: S1 with Tonsil^®; S2 with Aerosil^®; S3 with Aerosil^® + Proviplast; and S4 with Sabosorb. They were complexly characterized by FT-IR spectroscopy, differential scanning calorimetry, mechanical tests on different temperatures, and absorption of the saline solution. FTIR shows a proper embedding of the filler component into the polymer matrix and DSC presents a good stability at the living body temperature for all prepared samples. Micro and nanostructural aspects were evidenced by SEM and AFM microscopy, revealing that S3 has the most compact and uniform filler distribution and S4 has the most irregular one. Thus, S3 evidenced the best diametral tensile strength and S4 evidenced the weakest values. All samples present the best bending strength at 18 °C and fair values at 4 °C, with the best values being obtained for the S1 sample and the worst for S4. The lack of mechanical strength of the S4 sample is compensated by its best resistance at liquid penetration, while S1 is more affected by the liquid infiltrations. Finally, results show that PLA composites are suitable for biodegradable and disposable food packages, and the desired properties could be achieved by proper adjustment of the filler proportions.