This study focuses on polyamide 6/organo-modified montmorillonite (PA6/OMMT) nanocomposites as potential liner materials, given the growing interest in enhancing the performance of type IV composite overwrapped hydrogen storage pressure vessels. The mechanical properties of PA6/OMMT composites with varying filler concentrations were investigated across a temperature range relevant to hydrogen storage conditions (−40 °C to +85 °C). Liner collapse, a critical issue caused by rapid gas discharge, was analyzed using an Ishikawa diagram to identify external and internal factors. Mechanical testing revealed that higher OMMT content generally increased stiffness, especially at elevated temperatures. The Young’s modulus and first yield strength exhibited non-linear temperature dependencies, with 1 wt. per cent OMMT content enhancing yield strength at all tested temperatures. Dynamic mechanical analysis (DMA) indicated that OMMT improves the storage modulus, suggesting effective filler dispersion, but it also reduces the toughness and heat resistance, as evidenced by lower glass transition temperatures. This study underscores the importance of optimizing OMMT content to balance mechanical performance and thermal stability for the practical application of PA6/OMMT nanocomposites in hydrogen storage pressure vessels.

This study investigates the hydrogen permeability of injection-molded polyamide 6 (PA6) nanocomposites reinforced with organo-modified montmorillonite (OMMT) at varying concentrations (1, 2.5, 5, and 10 wt. %) for potential use as Type IV composite-overwrapped pressure vessel (COPV) liners. While previous work examined their mechanical properties, this study focuses on their crystallinity, morphology, and gas barrier performance. The precise inorganic content was determined using thermal gravimetry analysis (TGA), while differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and scanning electron microscopy (SEM) were used to characterize the structural and morphological changes induced by varying filler content. The results showed that generally higher OMMT concentrations promoted γ-phase formation but also led to increased agglomeration and reduced crystallinity. The PA6/OMMT-1 wt. % sample stood out with higher crystallinity, well-dispersed clay, and low hydrogen permeability. In contrast, the PA6/OMMT-2.5 and -5 wt. % samples showed increased permeability, which corresponded to WAXD and SEM evidence of agglomeration and DSC results indicating a lower degree of crystallinity. PA6/OMMT-10 wt. % showed the most-reduced hydrogen permeability compared to all other samples. This improvement, however, is attributed to a tortuous path effect created by the high filler loading rather than optimal crystallinity or dispersion. SEM images revealed significant OMMT agglomeration, and DSC analysis confirmed reduced crystallinity, indicating that despite the excellent barrier performance, the compromised microstructure may negatively impact mechanical reliability, showing PA6/OMMT-1 wt. % to be the most balanced candidate combining both mechanical integrity and hydrogen impermeability for Type IV COPV liners.

Microplastic (MP) pollution in river systems has become an increasing environmental concern, particularly in transboundary rivers such as the Danube. This study provides the first detailed assessment of microplastic contamination in the Szigetköz section of the Danube and its major tributary, the Mosoni-Danube. Depth-resolved pumped water samples were collected at three locations (Rajka, Mecsér and Gönyű) and analysed using Fourier Transform Infrared (FTIR) spectroscopy combined with automated spectral evaluation. MP concentrations showed a clear downstream increase, with average values of 83.8 particles/m³ at Rajka, 237.6 particles/m³ in the Mosoni-Danube at Mecsér, and 795.9 particles/m³ at Gönyű. Polyethylene (PE) was the dominant polymer in the tributary (70.6%), whereas both PE and alkyd resins were prevalent at the main Danube sites (Rajka: alkyd 37.7%, PE 31.8%; Gönyű: alkyd 39.9%, PE 37.3%). Particle size distribution also shifted downstream, with a higher proportion of smaller (50–100 μm) particles detected at Gönyű compared to upstream sites. The results suggest that the tributary may represent an important input to the main Danube channel in this section, while differences in polymer composition point to varying source characteristics within the study area. These findings provide an important baseline for future monitoring and support the development of targeted mitigation strategies in this transboundary river system.

Metal additive manufacturing is receiving increased attention today, as major industries such as the automotive, aerospace, and medical sectors place a stronger emphasis on it. Among the numerous technologies, fused filament fabrication (FFF) is gaining more focus due to its relatively low equipment cost and ease of application. The production of a solid metal part begins with the extrusion of a metal powder-filled filament, followed by printing, debinding, and heat treatment, through which the final strength is achieved. Among the commercially available filaments, stainless steel–based composites are the most widespread, as they offer good printability, corrosion resistance, and mechanical stability. The two most used materials in this category are BASF Ultrafuse 316L and Markforged 17-4PH alloys. These two materials lend themselves well to comparison, as they are designed for the same manufacturing technology but exhibit different metallurgical behaviors and process requirements, thus providing a comprehensive view of the capabilities and limitations of metal FFF technology. In this study, we aim to demonstrate how these two materials differ in their processing requirements, microstructural evolution, and resulting mechanical performance, and to show what can be achieved when manufacturing metal composites using FFF technology. The main differences between the two filaments are presented in a comparative table to provide a clear and structured overview of their distinct characteristics.

This study explores how atmospheric-pressure plasma treatments can modify the surface properties of polyamide 6 (PA6) and its nanocomposites reinforced with organomodified montmorillonite (OMMT), materials developed as potential liners for Type IV composite overwrapped pressure vessels (COPVs) designed for hydrogen storage. Four material compositions were examined: neat PA6 and composites containing 1, 2.5, 5, and 10 wt.% OMMT. Two different plasma systems—a piezoelectric plasma brush and a rotary plasma source—were used to activate the surfaces, and their effects were evaluated using water contact angle (WCA) measurements and Fourier transform infrared spectroscopy (FTIR). Both plasma treatments effectively increased the wettability of the tested materials, but the rotary plasma consistently produced the lowest WCA values across all compositions, reaching as low as 21° for neat PA6. These findings suggest that the rotary plasma’s higher power and dynamic exposure enhance the formation of polar functional groups and may increase micro-scale roughness, leading to improved surface activation. FTIR results confirmed the appearance and growth of oxidized functional groups, particularly carbonyl and hydroxyl species, which are linked to the increased surface polarity and hydrophilicity. Time-dependent contact angle tests revealed that the effects of plasma treatment were not permanent. Over several hours, the contact angles gradually increased, returning close to untreated values.

The low surface energy of many engineering thermoplastics limits their adhesive bonding performance, making surface activation an essential pre-treatment. This study compares the effects of atmospheric-pressure nitrogen and argon plasma treatments on the wettability and adhesive bond strength of five engineering thermoplastics [polypropylene (PP), high-impact polystyrene (HIPS), poly(vinyl chloride) (PVC), polycarbonate (PC), and polyethylene terephthalate (PET)] under identical processing conditions. Surface wettability was evaluated by water contact angle measurements, while adhesive performance was assessed by lap shear testing. Both plasma gases significantly improved the wettability and adhesive performance of all investigated polymers compared with untreated surfaces. Nitrogen plasma generally produced lower water contact angles, whereas argon plasma provided a wider processing window without visible surface degradation and achieved comparable or even higher bond strength for several polymer–adhesive systems. Although plasma treatment generally increased lap shear strength, the lowest water contact angle did not always correspond to the highest bond strength, demonstrating that adhesion depends not only on wettability but also on plasma-induced changes in surface characteristics and adhesive compatibility. The results provide practical guidance for selecting plasma treatment conditions and demonstrate that optimizing plasma-assisted adhesive bonding requires consideration of both the polymer substrate and the adhesive system.