The need to recycle carbon-fibre-reinforced composite polymers (CFRP) has grown significantly to reduce the environmental impact generated by their production. To meet this need, thermoreversible epoxy matrices have been developed in recent years. This study investigates the performance of an epoxy vitrimer made by introducing a metal catalyst (Zn²⁺) and its carbon fibre composites, focusing on the healing capability of the system. The dynamic crosslinking networks endow vitrimers with interesting rheological behaviour; the capability of the formulated resin (AV-5) has been assessed by creep tests. The analysis showed increased molecular mobility above a topology freezing temperature (T_v). However, the reinforcement phase inhibits the flow capability, reducing the flow. The fracture behaviour of CFRP made with the vitrimeric resin has been investigated by Mode I and Mode II tests and compared with the conventional system. The repairability of the vitrimeric CFRP has been investigated by attempting to recover the delaminated samples, which yielded unsatisfactory results. Moreover, the healing efficiency of the modified epoxy composites has been assessed using the vitrimer as an adhesive layer. The joints were able to recover about 84% of the lap shear strength of the pristine system.

Polymeric coatings represent a well-established protection system that provides a barrier between a metallic substrate and the environment. The development of a smart organic coating for the protection of metallic structures in marine and offshore applications is a challenge. In the present study, we investigated the use of self-healing epoxy as an organic coating suitable for metallic substrates. The self-healing epoxy was obtained by mixing Diels–Alder (D–A) adducts with a commercial diglycidyl ether of bisphenol-A (DGEBA) monomer. The resin recovery feature was assessed through morphological observation, spectroscopic analysis, and mechanical and nanoindentation tests. Barrier properties and anti-corrosion performance were evaluated through electrochemical impedance spectroscopy (EIS). The film on a metallic substrate was scratched and subsequently repaired using proper thermal treatment. The morphological and structural analysis confirmed that the coating restored its pristine properties. In the EIS analysis, the repaired coating exhibited diffusive properties similar to the pristine material, with a diffusivity coefficient of 1.6 × 10⁻⁶ cm²/s (undamaged system 3.1 × 10⁻⁶ cm²/s), confirming the restoration of the polymeric structure. These results reveal that a good morphological and mechanical recovery was achieved, suggesting very promising applications in the field of corrosion-resistant protective coatings and adhesives.

The use of 3D printing technology for manufacturing new products based on sustainable materials enables one to take advantage of secondary raw materials derived from recycling. This work investigates the structural performances of 3D printing composite filaments based on polylactic acid (PLA), as a matrix, reinforced by recycled carbon fiber (rCF). Carbon fibers were recovered from industrial scraps by a patented thermal process and used to produce thermoplastic composite filaments for additive manufacturing without any additional treatment and additives. The influence of the recovered carbon fiber (rCF) content on the thermal properties, mechanical properties and microstructure of the composites was studied in the range of 3–20 wt%. The recorded TGA curves exhibited a one-stage weight loss within the temperature range 290–380 °C for all samples and the residual rCF content was in good agreement with the theoretical fiber loading. The Young modulus of the extruded filaments strongly increased below a critical content (5 wt%), while at higher content the improvement was reduced. An increase in the storage modulus of 54% compared to neat PLA 3D printed sample resulted in a printed specimen with a higher rCF content. SEM images highlighted a strong rCF prevailing alignment in the direction of the extrusion flow, creating almost unidirectional reinforcement inside the filament. These findings suggest that homogeneous composite filaments reinforced with well-dispersed recycled CF without additional chemical modification and additives are suitable materials for additive manufacturing. The effect of rCF topological distribution within the material on the mechanical performances has been discussed, highlighting that the isolated fibers could efficiently transfer loads with respect to the percolated 3D network and have been correlated with the microstructure.

The process of curing of large thick composite parts needs attention regarding the formation of residual stresses. Similarly, novel reactive thermoplastics need investigating to produce an efficient thermal cure profile that decreases the risk of warpage and residual stress. In this work, the polymerization kinetics of the Elium resin system is investigated by differential scanning calorimetry (DSC) tests, the analysis of thermo-grams, and the parameters of Kamal and Sourour’s semi-empirical model. A numerical model based on finite elements was set up to reproduce the temperature fields during part consolidation. Several processing conditions were investigated (dwell temperature, environment, heat exchange) in order to predict the thermal gradient within the part. The optimal cure profile was identified as a function of process parameters with the aim of minimizing the thermal gradient within the composite element. The analysis revealed that, for the reactive thermoplastic Elium, the consolidation in facilities with high thermal exchange may increase the risk of residual stresses within the parts, erasing the advantage of short cure cycles.

In the present work, a commercial epoxy based on epoxy anhydride and tertiary amine was modified by a metallic catalyst (Zn²⁺) to induce vitrimeric behavior by promoting the transesterification reaction. The effect of two different epoxy/acid ratios (1 and 0.6) at two different zinc acetate amounts (Zn(Ac)₂) on the thermomechanical and viscoelastic performances of the epoxy vitrimers were investigated. Creep experiments showed an increase in molecular mobility above the critical “Vitrimeric” temperature (T_v) of 170 °C proportionally to the amount of Zn(Ac)₂. A procedure based on Burger’s model was set up to investigate the effect of catalyst content on the vitrimer ability to flow as the effect of the dynamic exchange reaction. The analysis showed that in the case of a balanced epoxy/acid formulation, the amount of catalyst needed for promoting molecular mobility is 5%. This system showed a value of elastic modulus and dynamic viscosity at 170 °C of 9.50 MPa and 2.23 GPas, respectively. The material was easily thermoformed in compression molding, paving the way for the recyclability and weldability of the thermoset system.

The use of high thermal conductive materials for heat transfer is gaining attention as a suitable treatment for improving battery performance. Thermal runaway is a relevant issue for maintaining safety and for proficient employment of accumulators; therefore, new solutions for thermal management are mandatory. For this purpose, a hierarchical nanomaterial made of graphite nanoplatelet has been considered as an interface material. High-content graphite nanoplatelet films have very high thermal conductivity and might improve heat dissipation. This study investigates the effect of a thermally conductive material as a method for safety enhancement for a battery module. A numerical model based on the finite element method has been developed to predict the heat generation during a battery pack’s charge and discharge cycle, using the Multiphysics software Comsol. The lumped battery interface generates appropriate heat sources coupled to the Heat Transfer Interface in 3D geometry. Simulation results show that the protection of neighbouring cells from the interleaved layer is fundamental for avoiding heat propagation and an uncontrollable heating rise of the entire battery pack. The use of graphite nanocomposite sheets could effectively help to uniform the temperature and delay the TR propagation.