Abstract

Reprocessable, repairable, and recyclable thermoset composites have the potential to improve the circularity of composites and ensure their sustainability. Disulfide-based epoxy matrices are under development to meet the specifications of key sectors (transport, wind energy, etc.). The manufacturing of reinforced composites by different techniques (infusion, prepregs, etc.) has been validated (TRL 4-5). The incorporation of new functionalities, such as fire resistance, and the validation of recycling are now on the table. Conventional chemical recycling separates the reinforcement from the composite for reuse, leaving aside the polymer matrix. The new functionalities incorporated require recovery and validation of the matrix. Dynamic resins allow milder conditions to be applied during recycling, and the challenge remains to find new applications that reuse these recycled products. On the other hand, the rational use of resources demands for new recycling routes that do not require separation of the components, apply few steps, be economically viable, and maintain the value of the reinforcement and the matrix. Vitrimers allow the thermoforming of composite parts through the application of heat and pressure. This process opens the way from reusing final parts with new shapes to generating short new fibre composites from mechanical pre-crushing. This communication will present the latest developments and objectives of several European projects funded under the HE framework (SURPASS, GA no. 101057901; MC4, GA no. 101057394) in which work on the maturity of the technologies is in progress.

Abstract

The use of fiber-reinforced polymer (FRP) composites in structural applications is increasingly widespread due to their light weight and load-bearing capacity. However, their behavior under fire exposure presents unique challenges—such as thermal buckling and post-buckling response—that current regulations, including Eurocode and SOLAS, do not specifically address. This work investigates the phenomenon of thermo-inelastic buckling in composites, taking into account their flexibility, thermal degradation, and natural imperfections. A modeling approach is proposed that integrates Felippa’s corotational theory, isotropic damage models with SPROM, and thermo-mechanical coupling. These methodologies are validated across scenarios ranging from one-dimensional to three-dimensional thermal buckling, including experimental validation. The results highlight the limitations of traditional approaches based on slenderness and inelasticity, such as the Tsai-Wu method, and emphasize the need for design frameworks that incorporate structural fire response in composite materials. This work aims to bridge the gap between the growing use of these materials and the design methodologies required for fire-resistant applications.