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.

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%.

This study investigated the creation of nano-composites using recycled LDPE and added 7.5 wt% nanofillers of Al and Fe in two varying particle sizes to be used as hot-melt adhesives for reversible bonding processes with the use of microwave technology. Reversible bonding relates to circular economy enhancement practices, like repair, refurbishment, replacement, or renovation. The physical–chemical, mechanical, and dielectric characteristics were considered to determine the impact of particle size and metal type. Through the investigation of electromagnetic radiation absorption in the composites, it was discovered that the optimal bonding technique could potentially involve a frequency of 915 MHz and a power level of 850 × 10³ W/kg, resulting in an efficient process lasting 0.5 min. It was ultimately proven that the newly created hot-melt adhesive formulas can be entirely recycled and repurposed for similar bonding needs.

The article explains how to make thermoplastic construction materials by combining waste from chicken feathers with plastic waste. The initial phase focused on a new and environmentally friendly method of sterilizing raw feathers using microwave radiation inside sealed ovens with circulating air. Additionally, composites containing varying feather amounts using two different polymer matrices were fabricated through an injection process, followed by mechanical and physical tests on the samples. Because of their excellent characteristics, products made from a combination of chicken feather waste and plastic waste could effectively replace traditional wood–plastic composites that are polyvinyl chloride-based. The recycling technology was assessed for its environmental impact, and sustainability was proven economically and environmentally.

This paper describes the process to obtain ceramic nanotubes from titanium dioxide, alumina and yttrium oxide by a feasible, replicable and reliable technology, including three stages, starting from an electrospinning process of poly(methyl methacrylate) solutions. A minimum diameter of 0.3 μm was considered optimal for PMMA nanofibers in order to maintain the structural stability of covered fibers, which, after ceramic film deposition, leads to a fiber diameter of 0.5–0.6 μm. After a chemical and physical analysis of the stages of obtaining ceramic nanotubes, in all cases, uniform deposition of a ceramic film on PMMA fibers and, finally, a uniform structure of ceramic nanotubes were noted. The technological purpose was to use such nanotubes as ingredients in screen-printing inks for electrochemical sensors, because no study directly targeted the subject of ceramic nanotube applications for printed electronics to date. The printing technology was analyzed in terms of the ink deposition process, printed electrode roughness vs. type of ceramic nanotubes, derived inks, thermal curing of the electrodes and the conductivity of electrodes on different support (rigid and flexible) at different curing temperatures. The experimental inks containing ceramic nanotubes can be considered feasible for printed electronics, because they offer fast curing at low temperatures, reasonable conductivity vs. electrode length, good printability on both ceramic or plastic (flexible) supports and good adhesion to surface after curing.

This research examined the development and testing of hot-melt adhesives incorporating metallic (Al and Fe powders averaging 800 nm) and ferrite additives, designed for reversible bonding technology of polyolefins through electromagnetic energy. The experimental models with Al displayed smooth particles that were fairly evenly distributed within the polymer matrix. Experimental models with Fe suggested that Fe nanopowders are more difficult to disperse within the polymer matrix, frequently resulting in agglomeration. For ferrite powder, there were fewer agglomerations noticed, and the dispersion was more uniform compared to similar composites containing Fe particles. Regarding water absorption, the extent of swelling was greater in the composites that included Al. Because of toluene’s affinity for the matrices, the swelling measurements stayed elevated even with reduced exposure times, and the composites with ferrite showed the lowest swelling compared to those with metallic particles. A remarkable evolution of the dielectric loss factor peak shifting towards higher frequencies with rising temperatures was observed, which is particularly important when the materials are exposed to thermal activation through electromagnetic energy. The reversible bonding experiments were performed on polyolefin samples which were connected longitudinally by overlapping at the ends; specialized hot-melts were employed, using electromagnetic energy at 2.45 GHz, with power levels between 140 and 850 × 10³ W/kg and an exposure duration of up to 2 min. The feasibility of bonding polyolefins using homologous hot-melts that include metallic/ferrite elements was verified. Composites with both matrices showed that the hot-melts with Al displayed the highest mechanical tensile strength values, but also had a relatively greater elongation. All created hot-melts were suitable for reversible adhesion of similar polyolefins, with the one based on HDPE and Fe considered the most efficient for bonding HDPE, and the one based on PP and Al for PP bonding. When bonding dissimilar polyolefins, it seems that the technique is only effective with hot-melts that include Al. According to the reversible bonding diagrams for specific substrates and hot-melt combinations, and considering the optimization of energy consumption in relation to productivity, the most cost-effective way is to utilize 850 × 10³ W/kg power with a maximum exposure time of 1 min.