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The paper presents the characterization of 5 polymer composite materials with a polypropylene (PP) matrix obtained with different (mass) concentrations of strontium ferrite (Fe12SrO19) reinforcement that have synergistic protective properties against electrostatic discharges (ESD) and electromagnetic impulses (EMI). These types of composites can be used to protect electronic equipment. To this purpose, suitable polymer composites were developed using SrFe12O19 type filler in two forms (powder and concentrate). The weight ratio of the PP/SrFe12O19 composites obtained by the extrusion process and injection from the melt is 75/25 and 70/30. The characterization of these composite materials consisted of carrying out some physico-chemical tests to determine the hydrostatic density and the resistance to the action of water, as well as FTIR, UV-Vis analyzes and dielectric, magnetic and functional tests to identify the simultaneous protection performance at electromagnetic shielding and electrostatic discharges, which can occur in the electro-technical, electronics and automotive industries. It is also found that all composite materials presented reflection shielding properties (SER) in the range: -71.5 dB...to -56.7 dB, indicating very low absorption shielding. The best performing material was the PP/SrFe12O19 powder composite with a weight ratio of 70/30. At the same time, EDS tests were also carried out on these materials. For these applications, the surface resistance Rs and the point-to-point resistance Rp were tested. Recommended composites for simultaneous EMI and sensitivity to electrostatic discharges (ESD) functionality, in order of their performance, are M2 (with 30% ferrite powder) and M1 (with 25% ferrite powder). M4 composite (with 30% ferrite powder concentrate) can also be used at the limit. Following the research carried out, the obtained results recommend the composite with promising simultaneous operations as M2 (with 30% ferrite powder). The element of originality consists of obtaining polymer composites with simultaneous properties of protection against electromagnetic impulses and electrostatic discharges. [ABSTRACT FROM AUTHOR]

The paper presents a technological approach for obtaining sintered components with tailored electromagnetic features from electromagnetically active powders through the selective recycling of electronic waste, in particular scrap electronic components. Printed circuit board (PCB) scraps were submitted to a succession of grinding processes, followed by progressive magnetic and electrostatic separation, resulting two final fractions: metallic particles and non-metallic particles including different metallic oxides. Three types of powders were analyzed, i.e., powder after fine grinding, after magnetic separation and after electrostatic separation, which were further processed within a spark plasma sintering furnace in order to obtain solid disk samples. All samples contained several classes of oxides, and also residual metals, leading to specific thermal decomposition processes at different temperatures, depending on the nature of the oxides present in the studied materials. The chemical analysis of powders, via spectrometry with X-ray fluorescence—XRF, emphasized the presence of a mixture of metal oxides and traces of metals (mainly Ag), with concentrations diminishing along with the purification process. The most important analysis was related to dielectric parameters, and it was concluded that the powders obtained by the proposed technology could efficiently substitute scarce raw materials actually used as additives in composites, coatings and paints, mainly due to their high permittivity (above 6 in all frequency domains) and, respectively, dielectric loss factor (above 0.2 in all cases, in all frequency domains). We estimate that the technology described in this paper is a sustainable one according to the concept of circular economy, as it could reduce, by a minimum of 15%, the embodied GHG emissions generated from information and communications technology (ICT) devices by advanced recycling. [ABSTRACT FROM AUTHOR]

This paper describes the process used to produce thermoplastic building materials from non-recyclable mixed plastic–paper packaging waste. A first step was dedicated to an innovative and sustainable sterilization technology for non-recyclable waste, based on exposure to microwave radiation in closed air-circulation ovens. Further, composites with different cellulose contents and with two polymer matrices, respectively, were obtained using an injection process, and the samples were subjected to mechanical and physical tests. Due to their superior features, the products based on mixed polypropylene–paper packaging waste may successfully replace the classic polyvinylchloride-based wood–plastic composites. The environmental impact of mixed plastic–paper packaging waste was analyzed, and the sustainability of the thermoplastic technology was demonstrated from an economic and environmental point of view. [ABSTRACT FROM AUTHOR]

The paper describes the process of obtaining geopolymer composites using raw materials from critical waste, i.e., mixed power plant ash and furnace slag powder. Using such geopolymer composites, structural insulation panels were made in the laboratory, which were subjected to tests specific to construction applications. At the same time, some special properties, such as sound insulation and electromagnetic shielding properties for special applications, were tested. The results obtained from the functional tests led to the conclusion that the panels made of geopolymer composites provided both sound and electromagnetic attenuation values clearly superior to those obtained from autoclaved cellular concrete, brick, or concrete structures, which encourages us to suggest such material concepts for complex shielding purposes. The sustainability of the technology for producing such geopolymer composites was fully demonstrated from the economic, environmental, and social perspectives. [ABSTRACT FROM AUTHOR]

The piezocomposites from poly-(vinylidene fluoride) (PVDF) with BaTiO3 (BT) are largely presented in literature, but the composites from polydimethylsiloxane (PDMS) with BT consist a very new scientific preoccupation. The novelty of the paper lies in a new simpler route of preparation of the two composites with PDMS and respectively PVDF matrix, with tailored deposition on specific substrates for microelectronic use (e.g. indium-tin-oxide ITO/glass, Si/Pt, polyethylene terephthalate PET), along with an extensive comparation of their dielectric features, a consistent comparison of the influence of polymer matrix upon the piezoelectric features, and a demonstration of direct use for microelectronic applications of the composites of BT with PDMS. An interesting effect is observed around 100 kHz domain, determined by the activity and architecture of BT particles mainly for the BTPDMS composites, which induce an additional ionic-dipolar conjugated polarization, as a displacement due to the balance between the resonance and anti-resonance frequency. Such phenomena explain the potential use of such composites as resonators/filters, and BT-PDMS composites should be further investigated for tailored applications in radiofrequency electronic field. We can appreciate that superior piezoelectric features are offered by the composites of BT with PDMS, comparing to the composites with PVDF, which means that the composites of BT with PDMS were worth to study, leading to more versatile variants of electronic characteristics and with superior values. [ABSTRACT FROM AUTHOR]

The purpose of this work was to obtain an elastic composite material from polymer powders (polyurethane and polypropylene) with the addition of BaTiO3 until 35% with tailored dielectric and piezoelectric features. The filament extruded from the composite material was very elastic but had good features to be used for 3D printing applications. It was technically demonstrated that the 3D thermal deposition of composite filament with 35% BaTiO3 was a convenient process for achieving tailored architectures to be used as devices with functionality as piezoelectric sensors. Finally, the functionality of such 3D printable flexible piezoelectric devices with energy harvesting features was demonstrated, which can be used in various biomedical devices (as wearable electronics or intelligent prosthesis), generating enough energy to make such devices completely autonomous only by exploiting body movements at variable low frequencies. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Composite materials are materials with anisotropic properties that are created by combining several different components in a way that allows the best qualities of each component to be used. In this paper, raw materials were used to obtain composite materials of the type TPU/PP/BaTiO3 powder. The thermogravimetric analysis, dynamic differential calorimetry, and scanning electron microscopy were carried out. The preliminary tests for making specific filaments for 3D printing with a diameter of 1.75 mm were carried out on a laboratory extruder. The purpose of the experiment was to develop the optimal extrusion temperatures and the speed of drawing the filament to make filaments with rigorously constant dimensions, and the variation in diameter had a maximum of 10%. [ABSTRACT FROM AUTHOR]

Composite materials are materials with anisotropic properties that are created by combining several different components in a way that allows the best qualities of each component to be used. In this paper, raw materials were used to obtain composite materials of the type TPU/PP/BaTiO 3 powder. The thermogravimetric analysis, dynamic differential calorimetry, and scanning electron microscopy were carried out. The preliminary tests for making specific filaments for 3D printing with a diameter of 1.75 mm were carried out on a laboratory extruder. The purpose of the experiment was to develop the optimal extrusion temperatures and the speed of drawing the filament to make filaments with rigorously constant dimensions, and the variation in diameter had a maximum of 10%.