This work is devoted to evaluating the effectiveness of the recovery of carbon fibers from end-of-life wind turbine blades in the pyrolysis process, and the use of those fibers in the production of flat composite panels. The recovery of carbon fibers from wind turbine blades uses a pyrolysis process at 500–600 °C in a non-oxidizing atmosphere, in such a way that makes it possible to preserve the shape and dimensions of the fibers. Using recycled carbon fibers, flat CFRP sheets with epoxy resin matrix were produced by pressing. Seven different series of samples were tested, which differed in fiber length, fiber orientation, and pressure holding time. The results obtained on the recycled fibers were compared to the original carbon fibers, cut to corresponding lengths. Additionally, one of the series was reinforced with a biaxial fabric. The most favorable pressing parameters are empirically found to be pre-pressing 2 MPa (10 min), and further pressing at a pressure of 7 MPa until the resin completely cross-linked (about 120 min). A number of tests were carried out to demonstrate the usefulness of pyrolytic fibers, including tensile strength of carbon fibers, bending strength, SEM observations, FT-IR, and Raman spectroscopy. The tests carried out on the carbon fibers show that the pyrolysis process used leaves about 2% of the matrix on the surface of the fiber, and the tensile strength of the fibers drops by about 20% compared to the new carbon fibers. The research results show that the use of the recycled carbon fibers in the production of flat composite plates is reliable, and their mechanical properties do not differ significantly from plates made of corresponding original carbon fibers. Composite panels with the pyrolytic fibers (274 MPa) show up to a 35% higher flexural strength than similarly produced panels with the original new carbon fibers (203 MPa), which means that the panels can be used in the production of elements for footbridges, bridges, pipelines, or structural elements of buildings and roofing.

In this paper, sedimentation inhibition attempts were examined using colloidal silica in a mathematical and experimental approach. Experimental results were validated by a two-step verification process. It was demonstrated that application of quantitative metallography and hardness measurements in three different regions of samples allows us to describe the sedimentation process using modified Stokes law. Moreover, proper application of Stokes law allows one to determine the optimal colloidal silica amount, considering characteristics of applied filler (alumina or graphite). The results of mathematical calculations have been confirmed experimentally—the experimental results show good agreement with the calculated data.

This study investigates the piezoelectric and piezotronic properties of a novel composite material comprising polyvinylidene fluoride (PVDF) and antimony sulphoiodide (SbSI) nanowires. The material preparation method is detailed, showcasing its simplicity and reproducibility. The material’s electrical resistivity, piezoelectric response, and energy-harvesting capabilities are systematically analyzed under various deflection conditions and excitation frequencies. The piezoelectric response is characterized by the generation of charge carriers in the material due to mechanical strain, resulting in voltage output. The fundamental phenomena of charge generation, along with their influence on the material’s resistivity, are proposed. Dynamic strain testing reveals the composite’s potential as a piezoelectric nanogenerator (PENG), converting mechanical energy into electrical energy. Comparative analyses highlight the composite’s power density advantages, thereby demonstrating its potential for energy-harvesting applications. This research provides insights into the interplay between piezoelectric and piezotronic phenomena in nanocomposites and their applicability in energy-harvesting devices.

Carbon nanocomposites have gained interest due to the rapid development of nanotechnology. The graphite-based composites have been demonstrated to possess unique mechanical, electrical, and thermal properties. This paper presents a facile one-step sonochemical synthesis of antimony sulfoiodide (SbSI)/graphite nanocomposite. The weight concentrations of graphite in the prepared material varied from 0% to 33.3%. The morphology and chemical composition of the SbSI/graphite nanocomposites are studied with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. SEM examination shows that SbSI/graphite nanocomposite consists of one-dimensional SbSI nanostructures and graphite microparticles. The influence of graphite concentration on the energy band gap of SbSI/graphite nanocomposite is investigated using diffuse reflectance spectroscopy (DRS). The prepared materials are cold-pressed to obtain the bulk samples. They are characterized by direct current (DC) electrical measurements and thermoelectric examination. The increase in the graphite concentration in the SbSI/graphite nanocomposite resulted in a significant reduction in the electrical resistivity of the material. The Seebeck coefficients of the pristine SbSI nanowires and SbSI/graphite nanocomposite are determined for the first time. The investigations of the thermoelectric effect reveal that these nanomaterials exhibited p-type electrical conductivity. The thermoelectric power factor of the SbSI/graphite nanocomposite is examined as a function of the graphite concentration. The presented work demonstrates the comprehensive optical, electrical, and thermoelectric characterization of novel hybrid SbSI/graphite nanocomposites, which has not been studied before.