The possibility to obtain resistant and reusable hollow devices with differentiated high porosity is difficult to achieve efficiently. To solve this problem, we propose a combined melt-wet processing, which allows predictable and tunable morphologies(1). The process consists in combining Material Extrusion (MEX) with salt leaching in distilled water. The raw materials used in this work were polyamide6 and NaCl as porogen agent. NaCl was used in three different granulometries. PA6/NaCl30/70%wt(2) filaments were produced by extrusion and all blends exhibited rheological and mechanical behaviour sufficiently suitable for 3D printing. The porous hollow devices were produced by MEX of previously extruded blends and subjected to salt leaching in distilled water. The porogen showed good dispersion in both filaments and printed devices; pore distribution range was consistent with the one of the three salt samples, so the morphology of the systems is predictable. Printed devices after leaching showed high porosity, according to theoretical porosity. Despite the high degree of voids, the devices have maintained sufficient compressive mechanical properties. Hollow devices were then filled with methylene-blue as model molecule, to test their release capability and the contextual possibility to control it by changing pores’ morphology(3). Peppas-Korsmeyer model confirmed that the release mechanism for all devices is anomalous, thus influenced by swelling and porosity. These results indicate that the controlled release of other molecules,i.e. drugs or fertilizers, is possible, confirming the versatility of the process.

Acknowledgement
This study was carried out within the SAMOTHRACE (sicilian micro and nano technology research and innovation center) extended partnership and received funding from the european union next-generationeu (Piano Nazionaled di Ripresa e Resilienza (PNRR) – missione 4 componente 2, investimento 1.5). This manuscript reflects only the authors’ views and opinions, neither the european union nor the european commission can be considered responsible for them.

Melt grafting by reactive extrusion is a well-established method for producing functional polymers [1]. This technique traditionally requires a peroxide initiator, which serves as a source of free radicals. Upon exposure to elevated temperatures, the peroxide decomposes, generating alkoxy radicals that abstract hydrogen atoms from the polymer chains, thereby forming active sites for grafting. A fundamental limitation of this process is that the rate of radical initiation depends on the peroxide half-life, which is strongly temperature-dependent. Most monomers are either volatile or decompose at the temperatures required for fast peroxide decomposition, this can limit grafting efficiency. Furthermore, handling peroxides poses serious safety concerns due to their unstable, reactive nature [2]. To address the challenge of decoupling radical initiation from the grafting reaction temperature and to encourage safer industrial practices, a novel radical initiation method involving the use of a cold atmospheric pressure plasma jet (CAPPJ) has been investigated. Plasma treatment has been widely used for surface modification, enhancing adhesion properties by promoting the formation of polar oxygen groups [3,4]. Recent findings have also demonstrated its efficacy in generating free radicals when applied in the melt state [5]. However, functionalization in the melt is constrained due to low oxygen availability. Thus, by coupling in-line plasma treatment in a batch mixer with the addition of a functional monomer, we have successfully grafted methacrylic acid (MAA) onto low-density polyethylene (LDPE) without the use of chemical initiators, paving the way for a continuous process of plasma-induced reactive extrusion.

Environmental pollution caused by plastic waste and concerns regarding the emission of greenhouse gases during incineration of plastic waste results in increased interest in biodegradable polymers produced from renewable resources. However, the industrial use of renewable polymers is often limited by their costs and less favourable physical and mechanical properties compared to conventional synthetic polymers. This holds even more for polymers used in strength dominated applications, for instance films, tapes, and textiles, e.g. weaves for flexible intermediate bulk containers, also called “BigBags”. In particular, the poor stretchability of renewable polymers is disadvantageous for packaging applications, in which stretching is key to achieve the required mechanical performance. Here, we investigated blending of various renewable polymer grades in various amounts that can be utilized in high-speed stretching, commonly applied in the industrial production of polymer tapes. Stretching at velocities of up to 800 mm/s, similar to industrial production of non-degradable synthetic polymers, allows for achieving much higher strength and stiffness as compared to conventional stretching at low velocity regularly performed in laboratory scale. This was enabled by using a custom-made setup installed on an injection molding machine and making use of the high opening-velocity of the device. The influence of the type and amounts of the various renewable polymers onto the stretchability as well as mechanical properties, in particular Young’s modulus and yield stress, of the prepared composites was evaluated. Stretched tapes based on TPS, PBAT, and PLA with high stretchability, modulus, and yield stress comparable to PE-HD and iPP were realized.

Fibre optic cables are commonly used in long-distance and high-performance data networks, including telecommunication, military, and medical purposes. Generally, fibre optic cables could be divided into two groups according to their application areas: indoor and outdoor. Cables dedicated to indoor application must meet rigorous fire-safety requirements in the European Union, which guide the selection of Flame Retardant, Non-Corrosive, Low Smoke Zero Halogen. Constantly increasing telecommunication market demand requires development of cable manufacturing technology to provide higher production capacity and cost optimization as well.
Commercially available thermoplastic FRNC compounds dedicated to fiber optic cables are based on linear low-density polyethylene /ethylene-vinyl acetate composites highly loaded with aluminum trihydroxide and magnesium dihydroxide fillers.
Objective of this work was to characterize an influence of temperature and thermomechanical degradation in extrusion process on properties of commercial FRNC cable compounds. Thermal degradation of cable materials was studied with use of thermogravimetry and rheometry. The series of jacket samples under different processing conditions were produced. Material processing behavior was characterized, and tensile and heat ageing performance of cable jacket were tested. The thermal analysis of materials allows to extend processing temperature to 200°C with satisfactory processing performance. Moreover, rheorogical analysis shows insignificant rheorogical changes up to 220⁰C. Characterization of mechanical properties of the cables shows relationship between production speed, processing temperature and processing profile type. The result and general approach to the FRNC investigation can be successfully used in cable industry or in other industries involving the extrusion of FRNC materials.

Over the past decades, polymer processing has advanced significantly, particularly in the precise control of the crystallizing microstructure in semi-crystalline polymers using virgin materials [1]. Optimized extruder designs have enabled efficient processing and compounding, making this a well-established field [2]. However, as the industry transitions toward circularity and sustainability, the challenges of recycling and reprocessing waste polymers become increasingly critical. Traditional melting strategies, designed for uniform virgin pellets, often fail when applied to recycled materials [3]. These materials typically consist of irregularly shaped granules or flakes, often containing mixtures of polyolefins with different molecular structures, melting points, and viscosities. Such variability complicates heat generation, heat transfer and flow behavior, leading to inefficient and inconsistent processing.

To address these challenges, we have developed a thermomechanically coupled framework that predicts heat generation during the deformation of various polyolefin materials [4]. By capturing the complex interactions between mechanical energy dissipation and thermal behavior, this framework provides valuable insights into the melting dynamics of mixed recycled streams under realistic extrusion conditions. It enables the identification of optimal processing parameters and helps in designing new melting strategies suited for post-consumer waste. This approach is crucial for improving the efficiency and consistency of polymer recycling, ultimately supporting the transition toward a more sustainable and circular plastics economy.