Claudio Tosto

This study evaluates the environmental and economic implications of manufacturing and chemically recycling a multifunctional carbon fiber (CF) epoxy laminate with an integrated crystalline-silicon photovoltaic (PV) cell. Primary material, energy, and waste data were collected during laboratory-scale manufacture and selective acid-mediated disassembly. A preliminary contribution analysis identified the photovoltaic cell and CF fabric as the dominant manufacturing hotspots, jointly accounting for approximately 85% of both climate change and fossil resource impacts. These findings guided a comparative cradle-to-gate life-cycle assessment of two multifunctionally equivalent laminates: a virgin-material system vs. a recycled-content system using recovered CFs and a PV cell. The recycled-content system reduced the considered environmental impacts by 55.9–98.2%, including a 57.6% reduction in climate change. A conservative component-level bounding analysis showed lower impacts for the recovered components across all EF 3.1 categories, with reductions ranging from 26.0% to 99.3% for the CF fabrics and from 47.0% to approximately 99.9% for the PV cell. The life-cycle costing model estimated a 28.0% cost reduction from EUR 10.17 to EUR 7.32 per multifunctional unit. Supplying 50% of process electricity from photovoltaics produced an additional 31% reduction in climate change impact. The results establish a primary-data case for integrating multifunctional-component recovery into composite circularity assessments while identifying laboratory scale and assumed multifunctional equivalence as the main limitations.

In this study, the effect of temperature on thermal-assisted glass delamination was investigated using two treatment conditions differing in the set temperature of the process (100 °C vs. 140 °C). Thermogravimetric Analysis (TGA) confirmed that ethylene-vinyl acetate (EVA) remains thermally stable up to about 280 °C, with degradation onset near 300 °C, ensuring that both treatments operate below decomposition. Differential Scanning Calorimetry (DSC) analysis identified an endothermic transition attributable to the melting of crystalline regions in EVA within the thermal range of 35–65 °C, indicating enhanced polymer chain mobility at elevated temperatures. This endothermic transition corresponds to the melting of polyethylene crystallites within the EVA copolymer and should not be interpreted as a glass transition, since the Tg of EVA is typically located at approximately −30 to −35 °C. Fourier Transform Infrared (FTIR) analysis verified preservation of ester functional groups, confirming the absence of chemical degradation. The morphological analysis performed via Scanning Electron Microscopy (SEM) revealed a clear temperature-dependent morphology of EVA after thermal-assisted delamination. At 140 °C, enhanced polymer softening and viscous flow led to smoother surfaces and more uniform interfacial separation, whereas at 100 °C, limited mobility resulted in heterogeneous, fragmented residues and predominantly cohesive failure. These results highlight that optimizing temperature is key to balancing effective delamination with residue minimization, supporting more sustainable PV recycling.

This study investigates the mechanical properties and thermal conductivity of metal parts produced using metal fused filament fabrication (Metal FFF), focusing on three distinct printing profiles (Fast, Strong, and Quality) provided by the material manufacturer. The correlation between thermal conductivity and mechanical strength is explored, aiming to optimize part performance by understanding the impact of printing parameters. Results demonstrate that the “Quality” profile delivers superior mechanical strength and thermal conductivity due to enhanced inter-layer bonding and reduced porosity, as confirmed by SEM analysis. Conversely, the “Fast” profile offers the lowest performance but maximizes productivity and cost-efficiency. The “Strong” profile represents a balanced compromise among mechanical performance, thermal properties, and manufacturing cost. This work highlights the potential of using thermal conductivity tests as a faster and more resource-efficient proxy for mechanical testing in initial assessments. Such tests are particularly valuable in applications where thermal conductivity is a critical requirement (e.g., battery thermal management systems, heat exchangers, cooling systems in electronic, etc.). Future research should focus on developing predictive models to further streamline the characterization and optimization of Metal FFF processes for industrial applications.

This study presents the chemical, thermal and mechanical characterization of two bio-based and fully-recyclable epoxy latent resins derived from pine oil, engineered to meet high-performance mechanical and thermal specifications for advanced composite applications. The characterized latent epoxy resins exhibited glass transition temperature (T _g ) values ranging between 90 and 120 °C, flexural strength and modulus values within the range of 35–110 MPa and 2.5–3.2 GPa, respectively, making them suitable for structural applications. One of the latent epoxy resin was further employed in the fabrication of a hybrid joint comprising metal and CFs reinforced composites characterized by an average ILSS of 11.9 MPa and a maximum load of 1429.2 N, due to a good mechanical interlocking at the metal/CFs interface. Due to its latent curing behavior, the epoxy resin remains stable until exposed to elevated temperatures (≥ 80 °C), at which point cross-linking is initiated. This property affords an extended pot life and improved control during application and assembly. This feature makes the system especially attractive for hybrid manufacturing approaches, where the extended open time supports accurate positioning of fibers and metal inserts. Furthermore, the epoxy resin was cross-linked by using a cleavable amine hardener to achieve full recyclability, so enabling disassembly under mild acidic controlled conditions. This property facilitated the full recovery of constituent raw materials through a targeted chemical recycling process, achieving a 100% recovery yield. The proposed system offers a sustainable alternative to conventional thermoset-based hybrid metal/CFs composite manufacturing and end-of-life management. This class of hybrid joints can find industrial applications in aerospace and automotive sectors, in electronic and optical applications, in sports equipment and biomedical devices, for the manufacturing of next-generation structural solutions, with enhanced performance and versatility, by also supporting the global shift toward circular design and responsible material use.

Glass fiber–reinforced polymer composites produced via sheet molding compound (SMC) and bulk molding compound (BMC) processes heavily rely on unsaturated polyester resins (UPRs) containing styrene, a volatile organic compound associated with environmental and health risks. In response to increasing regulatory pressure to reduce styrene emissions, this study investigates the formulation and performance of low‐styrene (10%wt) and styrene‐free UPR for SMC/BMC applications. Pure maleic‐based and isophthalic/maleic‐based polyester matrices were synthesized using 1,4‐butanediol dimethacrylate as an alternative reactive diluent. These resins were reinforced with short glass fibers to produce composite laminates via a combined SMC or BMC and hot pressing production process, which were evaluated for thermo‐mechanical properties and interfacial morphology. The isophthalic/maleic‐based formulation with 10 wt% styrene demonstrated superior mechanical performance (i.e., flexural strength: 119.83 ± 5.52 MPa) and comparable thermal stability ( T _g of 155°C) to conventional 30 wt% styrene systems, owing to improved fiber‐matrix adhesion. Conversely, pure maleic‐based systems exhibited higher flexural modulus but inferior mechanical strength due to poor interfacial bonding. Morphological and dynamic mechanical analyses confirmed the role of matrix structure and styrene content in governing performance. These findings demonstrate the feasibility of reducing styrene content in UPRs when optimized backbone chemical structure are used while maintaining industrially relevant processing and mechanical performance, thus supporting the transition toward sustainable composite manufacturing.

Carbon fiber-reinforced composites (CFRCs) are widely used in aerospace, automotive, and defense applications due to their high strength-to-weight ratio and excellent mechanical performance. In this study, cores and sandwich panels were fabricated via fused filament fabrication (FFF) using co-polyester filaments reinforced with 20 wt.% short carbon fibers. The mechanical response of the structures was evaluated under low-velocity impact (LVI) conditions using instrumented drop weight testing at energy levels ranging from 2 to 20 J. A three-factor, three-level full factorial experimental design was employed, considering build orientation (flat vs. upright), infill pattern (trihexagonal vs. triangular), and impact energy as factors. The maximum contact force was selected as the primary response variable. The results revealed that upright-printed specimens exhibited significantly improved impact resistance compared to flat-printed ones, with increases in peak force of up to 28% for cores and over 68% for sandwich structures. Among the tested infill geometries, the triangular pattern outperformed the trihexagonal one across all configurations and energy levels. The combination of upright orientation and triangular infill proved to be the most effective, providing enhanced energy absorption and reduced rear-side damage, especially under higher impact energies. These findings offer valuable insights into the design of lightweight, impact-resistant structures produced by additive manufacturing, with direct implications for structural components in demanding engineering environments.

This study aims to investigate the chemical recycling of two different fully recyclable bio-based epoxy matrices based on epoxidized precursors derived from waste flour. The key for their recyclability relies on the use of a cleavable hardener. In fact, the latter contains a ketal group in its chemical structure, which is cleavable in mild acetic conditions, so allowing for the breakage of the cured network. The recyclability was successfully assessed for both the two investigated formulations, with a recycling process yield ranging from 80 up to 85%. The recycled polymers presented a T_g up to 69.0 ± 0.4 °C, determined by mean of DMA and DSC analysis. Next, the TGA revealed that the thermal decomposition of the specimens primarily occurred around 320 °C and attributed to the breaking of C–O and C–N bonds in cross-linked networks. In the end, the chemical characterizations were carried out by mean of Py-GC/MS, MALDI-TOF-MS and FT-IR ATR. In fact, these analyses allowed for investigating how the recycled polymer’s structure changed, starting from the initial epoxy systems. These insights on their chemical structure could further allow for identifying re-use strategies in accordance with a circular economy approach.