Lilian Vanessa Rossa Beltrami

The increasing demand for lightweight and efficient ballistic protection systems has motivated polymer-based composites combining high impact resistance. In this study, nanostructured high-density polyethylene (HDPE) and low-density polyethylene (LDPE) films containing cellulose nanofibers (CNF), graphene nanoplatelets (GNP), or organoclay (CLAY), were produced by melt extrusion and combined with aramid fabric (AR) to manufacture multilayer composite plates through hot compression molding. The composites were characterized by Split Hopkinson Pressure Bar (SHPB) dynamic compression tests, ballistic impact tests following NIJ 0101.06 and NBR 15000 standards, backface deformation measurements, and tensile, flexural, and impact tests. Among the evaluated formulations, the composite containing 1.0 wt.% CNF exhibited the best overall mechanical performance under dynamic loading, showing higher stress, toughness, and energy absorption than the reference material. No plate was perforated and all backface deformations (22.2–29.1 mm) were below 44 mm, meeting the Level III-A criteria under the conditions adopted, although three formulations were impacted above the velocity tolerance (a more severe condition). The GNP and CLAY formulations exhibited the lowest backface deformation after ballistic impact, indicating enhanced energy dissipation. The results show that nanostructured HDPE/LDPE films reinforced with suitable nanofillers, particularly CNF, are promising for multilayer ballistic protection systems.

Nanocomposites are promising matrices for polymer electrolytes in lithium-polymer batteries, and TiO₂ nanoparticles are widely explored to enhance dynamic-mechanical and ionic properties. However, despite increasing interest in epoxy-based electrolytes, no study to date has concurrently reported dynamic-mechanical and electrochemical properties for the same epoxy-TiO₂ formulations. This prevents establishing structure–property relationships and represents a critical evidence gap. A search (2014–2024) across ScienceDirect, Scopus, Web of Science, and Springer identified eleven studies on epoxy-TiO₂ dynamic-mechanical behavior and five on polymer–particle electrolyte performance. Pearson’s r-test (5% significance) revealed a strong inverse correlation (r = −0.97) between Tan δ and Tg in epoxy nanocomposites containing 30–40 nm TiO₂ at 2–15 wt %, indicating a trade-off between damping and strength. Yet, although the review was originally designed to investigate whether these viscoelastic trends relate to electrochemical performance in semisolid epoxy-based electrolytes, such a link could not be established: no included study reported mechanical and electrochemical data for the same epoxy formulation. Limited data and experimental variability further hindered broader comparisons, especially between nanocomposites and polymer electrolytes. Notably, all conductivity improvements identified in polymer–particle systems occurred exclusively in nonepoxy matrices and therefore do not constitute evidence that TiO₂-induced mechanical enhancements in epoxy resins translate into electrochemical gains. Nonetheless, two studies showed simultaneous mechanical and ionic enhancements, suggesting that nanoparticle-induced structural rearrangements may facilitate Li⁺ transport. Overall, this review highlights the potential role of nanoscale ceramics as nanostructuring agents while underscoring the need for future studies that jointly evaluate mechanical and electrochemical properties in epoxy-based electrolytes.

Copper oxide nanoparticles (CuONPs) have received considerable attention because of their wide range of applications, particularly in the development of antimicrobial materials for medical, environmental, and industrial purposes. However, conventional synthesis routes often involve the use of toxic chemicals and environmentally harmful conditions. To overcome these limitations, green synthesis strategies have been developed as sustainable alternatives through the use of natural reducing and stabilizing agents. In this study, Citrus sinensis leaf extract, which exhibits high antioxidant capacity, was investigated for green synthesis of CuONPs, followed by their subsequent incorporation into a chitosan polymeric matrix. The optimal synthesis conditions were achieved at a pH of 7.0 using copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) at a concentration of 10.0 g L⁻¹ and a calcination temperature of 300 °C. The resulting CuONPs exhibited a heterogeneous morphology, with average particle sizes ranging from 20 to 30 nm, and demonstrated satisfactory antimicrobial activity against Escherichia coli and Staphylococcus aureus. The incorporation of these NPs into chitosan yielded composite materials with enhanced antimicrobial performance, highlighting the added value of polymer–NP hybrid systems. Although these composite materials were not evaluated under realistic operational conditions, the optimized green protocol provides a robust methodological basis for future studies targeting water disinfection and other environmentally relevant technologies.

The objective of the present study is to develop epoxy-based coating containing graphene nanoplatelets (0.25 (w/w)) coated with niobium at different concentrations (0.1, 0.5, 1, and 2% (w/w)) using magnetron sputtering technique for further use on an aluminum alloy panel (AA7075). Raman spectroscopy, wettability, impact, and corrosion resistance (ACET), electromagnetic shielding, and morphological analysis of the nanocomposites were performed. The hydrophobicity showed an increase of ∼27% for higher niobium concentrations (compared to the neat epoxy). Also, at higher niobium concentrations (1 and 2%), the electromagnetic shielding showed an attenuation peak at −8 dB for the frequency range 8–10 GHz (compared to a resonance peak of −6 dB at 10.2 G Hz for 0.5% Nb). The results showed that the incorporation of graphene nanoplatelets decorated with niobium proportionate an increase of 2 dB as electromagnetic barrier, which can be related to a conducted network formed by niobium on the surface of the coating via absorption mechanism magnetic properties. ACET showed an increase in the properties by higher niobium concentrations (1 and 2%), indicating an improvement in the shielding protection and corrosion resistance of the suggested composites. The other properties did not show any improvement of the properties.

The incorporation of graphene and montmorillonite clay (MMT30B) nanoparticles into photopolymerizable liquid acrylic resins for the fabrication of temporary crowns via 3D printing was evaluated. A slight color change was observed by incorporating 0.0025% graphene, which is acceptable for dental applications. The resin containing 0.0125% graphene exhibited superior abrasion resistance, with a lower mass loss (approximately 10% less than that of the neat resin). Resins containing 0.0125% graphene and 0.0125% MMT30B demonstrated higher compressive strength and elastic modulus, as well as an increase in Shore D hardness (average value of 83). Nanocomposites containing 0.05% and 0.10% graphene exhibited degradation onset temperatures of 274°C and 271°C, respectively. When combined with MMT30B, the nanocomposites with 0.0025%, 0.05%, and 0.10% nanofiller content showed onset temperatures of 268°C, 276°C, and 275°C, respectively—all higher than that of the neat resin (264°C). Thermal expansion was reduced to 0.12% in resins with 0.0125% graphene and 0.10% MMT30B, compared to 0.15% in the neat resin. However, the addition of nanofillers decreased the stiffness of the material. In conclusion, the nanocomposites obtained through the addition of graphene and MMT30B exhibited significant potential for dental applications.

The exposure of metals to corrosion results in significant economic and environmental losses. One approach to mitigate corrosion is the use of coatings, particularly organic coatings, which act as physical barriers, isolating the metal from corrosive environments. However, these coatings are prone to failure, leading to substrate exposure and subsequent corrosion. Smart self‐healing coatings have emerged as a promising solution by regenerating damage and restoring the protective barrier. In this study, a smart self‐healing coating was developed based on epoxy resin and microcapsules with urea‐formaldehyde walls, containing different active cores (epoxy, silicon alkoxide precursor, and imidazole). The coatings, incorporating 15 wt% microcapsules, were evaluated using the Accelerated Cyclic Electrochemical Technique (ACET). A controlled scratch was introduced on the sample surfaces, followed by six ACET cycles. Electrochemical tests revealed that all coatings containing microcapsules exhibited superior anticorrosive and self‐repair performance compared to the pure epoxy resin coating. The impedance modulus at 0.01 Hz increased from | Z | _0.01 = 506 Ω cm ² for the epoxy coating to | Z | _0.01 = 17,960 Ω cm ² for coatings containing microcapsules with an epoxy core. Nyquist plots showed larger semicircle radii, higher pore resistance, and lower capacitance with the addition of microcapsules.