This paper presents the obtaining and characterization of recycled polypropylene/strontium ferrite (PP/SrFe₁₂O₁₉) polymer composite materials with applications in the electromagnetic shielding of vehicle interiors (mainly automotive electronics—carcasses) from the electromagnetic radiation emitted mainly by exterior sources—electrical lines and supply sources—in terms of the development of the new electrical vehicles. With this aim, suitable polymer composite materials were developed using SrFe₁₂O₁₉ filler in two forms (powder and concentrate). The recycled PP polymer and composite materials with a PP/SrFe₁₂O₁₉ weight ratio of 75/25 and 70/30 were obtained in two stages, i.e., pellets by extrusion and samples for testing through a melt injection process. The characterization of the obtained materials took into account the requirements imposed by the desired applications. It consisted of determining the mechanical and dielectric properties, and microstructure analyses, along with the determination of the resistance to the action of a temperature of 70 °C, which is higher than the temperatures created during the summer inside vehicles. The performance of these materials as electromagnetic shields was assessed through functional tests consisting of the determination of magnetic permeability and the estimation of the electromagnetic shielding efficiency (SE). The obtained results confirmed the improvement of the mechanical, dielectric, and magnetic properties of the PP/SrFe₁₂O₁₉ composites compared to the selected PP polymers. It is also found that all the composite materials exhibited reflective shielding properties (SE_R from −71.5 dB to −56.7 dB), with very little absorption shielding. The most performant material was the composite made of PP/SrFe₁₂O₁₉ powder with a weight ratio of 70/30. The promising results recommend this composite material for potential use in automotive shielding applications against electromagnetic pollution.

The use of nanotechnologies in the applied biomedical sciences can offer a new way to treat infections and disinfect surfaces, materials, and products contaminated with various types of viruses, bacteria, and fungi. The Cu-Au nanoparticles (NPs) were obtained by an eco-friendly method that allowed the obtaining in a one-step process of size controlled, well dispersed, fully reduced, highly stable NPs at very mild conditions, using high energy ionizing radiations. The gamma irradiation was performed in an aqueous system of Cu²⁺/Au³⁺/Sodium Dodecyl Sulfate (SDS)/Ethylene Glycol. After irradiation, the change of color to ruby-red was the first indicator for the formation of NPs. Moreover, the UV-Vis spectra showed a maximum absorption peak between 524 and 540 nm, depending on the copper amount. The Cu-Au NPs presented nearly spherical shapes, sizes between 20 and 90 nm, and a zeta potential of about −44 mV indicating a good electrostatic stability. The biocidal properties performed according to various standards applied in the medical area, in dirty conditions, showed a 5 lg reduction for Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus hirae, a 5 lg reduction for both enveloped and non-enveloped viruses such as Adenovirus type 5, Murine Norovirus, and human Coronavirus 229E, and a 4 lg reduction for Candida albicans, respectively. Thus, the radiochemically synthesized Cu-Au alloy NPs proved to have high biocide efficiency against the tested bacteria, fungi, and viruses (both encapsulated and non-encapsulated). Therefore, these nanoparticle solutions are suitable to be used as disinfectants in the decontamination of hospital surfaces or public areas characterized by high levels of microbiological contamination.

The European methodology for plastics, as a feature of the EU’s circular economy activity plan, ought to support the decrease in plastic waste. The improvement of recycled plastics’ economics and quality is one important part of this action plan. Additionally, achieving the requirement that all plastic packaging sold in the EU by 2030 be recyclable or reusable is an important objective. This means that food packaging materials should be recycled in a closed loop at the end. One of the most significant engineering polymers is polyethylene terephthalate (PET), which is widely used. Due to its numerous crucial qualities, it has a wide variety of applications, from packaging to fibers. The thermoplastic polyolefin, primarily polyethylene and polypropylene (PP), is a popular choice utilized globally in a wide range of applications. In the first phase of the current experiment, the materials were obtained by hot pressing with the press machine. The reinforcer is made of Al nanopowder 800 nm and Fe nanopowder 790 nm and the quality of the recycled polymer was examined using Fourier transform infrared spectroscopy (FTIR), a scanning electron microscope (SEM), and differential scanning calorimetry (DSC). From DSC variation curves as a function of temperature, the values from the transformation processes (glass transition, crystallization, and melting) are obtained. SEM measurements revealed that the polymer composites with Al have smooth spherical particles while the ones with Fe have bigger rough spherical particles.

In this paper, the obtaining and characterization of five experimental models of novel polymer composite materials with ferrite nano-powder are presented. The composites were obtained by mechanically mixing two components and pressing the obtained mixture on a hot plate press. The ferrite powders were obtained by an innovative economic co-precipitation route. The characterization of these composites consisted of physical and thermal properties: hydrostatic density, scanning electron microscopy (SEM), and TG DSC thermal analyses, along with functional electromagnetic tests in order to demonstrate the functionality of these materials as electromagnetic shields (magnetic permeability, dielectric characteristics, and shielding effectiveness). The purpose of this work was to obtain a flexible composite material, applicable to any type of architecture for the electrical and automotive industry, necessary for protection against electromagnetic interference. The results demonstrated the efficiency of such materials at lower frequencies, but also in the microwave domain, with higher thermal stability and lifetime.

In this study, polymer matrix composites based on high-density polyethylene (HDPE) and recycled HDPE (HDPEr) were reinforced with zinc oxide nanoparticles (ZnO NPs). Four formulations (M1-M4) with HDPE/HDPEr/ZnO NP mass ratios of 50/50/0, 48/47/5, 45/45/10, and 43/42/15 were produced via melt injection molding. Disc-shaped samples (Ø30 ± 0.1 mm × 2 ± 0.1 mm) were evaluated in unaged and aged states (840 h at 100% humidity and 100 °C) using scanning electron microscopy, X-ray diffraction, ultraviolet–visible and Fourier-transform infrared spectroscopy, water absorption, thermal resistance, and mechanical and dielectric testing. Among all composites, M2 showed the best performance, with the highest aging resistance (estimated lifetime of 3891 h in humidity and 2361 h in heat). It also exhibited superior mechanical properties, with the highest indentation hardness, Vickers hardness, and elastic modulus before (0.042 GPa, 3.846 HV, and 0.732 GPa) and after aging under humidity (0.042 GPa, 3.932 HV, 0.706 GPa) and elevated temperature (0.085 GPa, 7.818 HV, 1.871 GPa). Although ZnO NPs slightly reduced electrical resistivity, M2 showed the most stable dielectric properties. In its unaged state, M2 had 22%, 30%, and 3% lower surface resistivity, volume resistivity, and dielectric strength, respectively, than M1 polymer. M2 was identified as the optimal formulation, combining mechanical strength, dielectric stability, and resistance to moisture and heat.

This research investigates novel polymeric composite materials for automotive interior trim applications. The composites utilize recycled polypropylene (PPr) matrix and carboxymethylcellulose (CMC) as filler (PPr/CMC: 100/0, 95/5, and 90/10 wt.%). The materials were processed by extrusion and injection molding. Considering their intended application, the composites were evaluated for resistance to key climatic factors, i.e., temperature, humidity, and UV radiation. In addition, structural analyses and FTIR analyses were performed to assess potential heterogeneity and thermal stability. Following FTIR tests, the incorporation of carboxymethyl cellulose in polypropylene is confirmed by the detection of characteristic CMC bands for -OH, C=O, and C-O-C groups. The results indicate slight structural heterogeneity in the 5% and 10% CMC composites. However, no thermal distortions were observed in either the composites or the PPr matrix itself. The behavior of PPr/CMC composites under the action of the mentioned climatic factors has been assessed from the variation of dielectric characteristics with frequency. The strong polarization of CMC leads to a sharp increase in composites electrical conductivity after submersion in water for 480 h, suggesting weakening of the composite structure. After exposure to UV radiation, a sharp increase in conductivity is observed even after the first cycle (72 h) of UV radiation. Following the experimental results obtained in our study, it is recommended to use the PPr +10% CMC composite for obtaining different interior ornaments (carpets, supports, etc.). At the same time, the use of these materials also has the advantage of lightening the mass of the vehicle due to their lower density than polymers.