Additive manufacturing technologies are gaining more and more attention, resulting in the development or modification of 3D printing techniques and dedicated materials. On the other hand, economic and ecological aspects force the industry to develop material recycling strategies. In this work, the multiple reprocessing of a commercially available PLA conductive composite with carbon black filler, dedicated to 3D printing, was investigated. The effects of extrusion temperature (190 °C and 200 °C) and reprocessing steps (1–5 steps) on the rheology, morphology, thermal and electrochemical properties of the conductive PLA 3D-printing filament were evaluated. The results showed deterioration of the thermal stability and material strength, as well as the influence of reprocessing on the melting point, which increases after initial melting. The electronic conduction mechanism of the composite depends on the percolation paths and it is also affected by the multiple processing. The reversibility of the [Fe(CN)₆]^3−/4− redox process diminishes with a higher degradation level of the conductive PLA. Importantly, the material fluidity was too high after the multiple reprocessing, which should be considered and suitably corrected during CB–PLA application as a 3D-printed electrode material.

Tutorial guide and critical review on conductive 3D-printing filaments for advanced electrochemical devices.

In this work, ground tire rubber (GTR) was thermo-mechanically treated in the presence of styrene-butadiene-styrene (SBS) copolymers. During preliminary investigation, the effects of different SBS copolymer grades, the variable content of SBS copolymer on the Mooney viscosity, and the thermal and mechanical properties of modified GTR were determined. Subsequently, GTR modified by SBS copolymer and cross-linking agents (sulfur-based system and dicumyl peroxide) was characterized by assessment of rheological, physico-mechanical, and morphological properties. Rheological investigations showed that linear SBS copolymer, with the highest melt flow rate among studied SBS grades, was the most promising modifier of GTR, considering processing behavior. It was also observed that an SBS improves the thermal stability of the modified GTR. However, it was found that higher content of SBS copolymer (above 30 wt%) does not bring any effective changes and, for economic reasons, is inefficient. The results showed that samples based on GTR modified by SBS and dicumyl peroxide have better processability and slightly higher mechanical properties compared to samples cross-linked by a sulfur-based system. This is due to the affinity of dicumyl peroxide to the co-cross-linking of GTR and SBS phases.

Plastic waste poses a serious threat to ecosystems and human health. Similarly, the increasing use of automobiles has led to a rise in discarded tires, exacerbating environmental concerns. However, repurposing this waste into new materials promotes sustainability and supports the concept of a circular economy. In this study, we explored the combination of reclaimed ground tire rubber (rGTR) and additive manufacturing technology (3D printing) for the development of novel conductive filaments. For this purpose, a filament composed of 25% rGTR, 25% carbon black (CB), and 50% low-density polyethylene (LDPE) was formulated for constructing additively manufactured electrodes. The produced filament exhibited excellent flexibility, with successful incorporation of rGTR into the matrix, as confirmed by TGA, SEM and AFM data. 3D-printed working electrodes prepared using rGTR, CB, and LDPE subjected to an atmospheric air plasma pen (3D-CB/rGTR/LDPE-PT) were applied for detecting a hazardous fungicide, carbendazim (CBZ). Thus, under optimized differential pulse voltammetry (DPV) conditions, the sensor demonstrated a linear response ranging from 1.0 to 40.0 μmol L⁻¹ CBZ, with limits of detection (LOD) and quantification (LOQ) of 79 nmol L⁻¹ and 262 nmol L⁻¹, respectively. The proposed 3D-CB/rGTR/LDPE-PT sensor was successfully applied for detecting CBZ in drinking water and effluent samples, achieving recovery rates between 95 and 105%, highlighting its excellent analytical performance. This work demonstrates that recycled raw materials from the automotive industry can be repurposed to develop innovative devices for detecting environmental contamination caused by indiscriminate pesticide use, while also simultaneously promoting sustainability through the reuse and recycling of waste tire rubber.

In this work, ground tire rubber and styrene–butadiene block copolymer (GTR/SBS) blends at the ratio of 50/50 wt%, with the application of four different SBS copolymer grades (linear and radial) and two types of cross-linking agent (a sulfur-based system and dicumyl peroxide), were prepared by melt compounding. The rheological and cross-linking behavior, physico-mechanical parameters (i.e., tensile properties, abrasion resistance, hardness, swelling degree, and density), thermal stability, and morphology of the prepared materials were characterized. The results showed that the selected SBS copolymers improved the processability of the GTR/SBS blends without any noticeable effects on their cross-linking behavior—which, in turn, was influenced by the type of cross-linking agent used. On the other hand, it was observed that the tensile strength, elongation at break, and abrasion resistance of the GTR/SBS blends cured with the sulfur system (6.1–8.4 MPa, 184–283%, and 235–303 mm³, respectively) were better than those cross-linked by dicumyl peroxide (4.0–7.8 MPa, 80–165%, and 351–414 mm³, respectively). Furthermore, it was found that the SBS copolymers improved the thermal stability of GTR, while the increasing viscosity of the used SBS copolymer also enhanced the interfacial adhesion between the GTR and SBS copolymers, as confirmed by microstructure evaluation.

Screw extrusion is a cost-effective and solvent-free method for manufacturing polymer blends and composites. This article reviews the latest developments in the field of multi-screw extruders, i.e. triple-screw, quad-screw, octa-screw, ring, planetary and multi-rotation system (MRS). The authors also discussed limitations and directions of multi-screw extruders development.