Issue 77

A. Casaroli et alii, Fracture and Structural Integrity, 77 (2026) 89-106; DOI: 10.3221/IGF-ESIS.77.07

effectively "burning" the resin to release the carbon fibres. Thermal processes can lead to a steady degradation of mechanical properties, making the recycled material significantly weaker than its virgin counterpart. For carbon fibres, the economic viability of thermal plants depends heavily on processing large volumes of material. The energy required to reach the decomposition temperatures of high-performance resins must be balanced with the market price of the recovered fibres. If degradation is too severe, potential customers may opt for new virgin fibres, thus limiting the market for recycled products. Chemical recycling uses solvents and catalysts to break the chemical bonds of the polymer matrix at relatively lower temperatures than pyrolysis [17]. This method is highly effective for fibre recovery with minimal surface damage and greater length retention. However, like thermal methods, chemical recycling requires sophisticated industrial infrastructure and is currently subject to rigorous evaluation regarding its economic feasibility and chemical waste stream management [18]. The choice of a recycling route is governed by a balance between the technology readiness level (TRL) and the waste treatment hierarchy (WTH). Traditional disposal methods, such as landfill, have the highest TRL score, indicating a fully mature and accessible "technology." However, landfill has the lowest possible WTH score, indicating its complete failure as a sustainable solution. From an economic perspective, the costs associated with landfill disposal are borne directly by the consumer, while the entire technological value of the composite is lost forever. This creates a strong incentive to switch to high-tech recovery. The challenge is that recycled fibres are not intrinsically equivalent to virgin fibres; specific differences in surface chemistry and mechanical strength influence the consumer's choice between virgin and recycled raw materials. In the short term, the carbon fibre recycling market is driven by the relatively low cost of recovery compared to the energy-intensive processes required to produce virgin PAN. For carbon fibres to achieve a truly circular lifecycle, the industry must overcome the economic barriers associated with high-tech processing facilities. Only by ensuring that recycled fibres can compete, both in terms of performance and cost, with virgin materials can the technological value associated with these advanced materials be preserved for future generations of engineering applications. As the market value of carbon fibres is expected to approach that of glass fibres in the next 15–20 years [19], the development of industrial-scale recycling solutions is no longer a marginal issue but a necessity for a sustainable composites market. This article aims to provide a comprehensive analysis of the mechanical and tomographic characterization of recycled CFRP obtained through an innovative, entirely mechanical, and environmentally sustainable process [20]. Materials and method detailed analysis was carried out to assess the mechanical behaviour of recycled CFRP produced using an innovative fully mechanical and environmentally sustainable process [20]. The main objective of this comprehensive series of analyses - which included Scanning Electron Microscopy of recycled non-woven fabric mats and carbon fibre powders, tensile tests on epoxy-impregnated carbon panels, and high-resolution tomographic analysis - was to systematically identify any latent issues within the recycling process. Ultimately, understanding these phenomena aims to formulate specific guidelines capable of improving the production quality and reliability of recycled carbon composite panels made of recycled CFRP. The samples provided for mechanical and tomographic evaluation consisted of two different types of recycled carbon panels, both produced by the controlled impregnation of recycled carbon fibre non-woven fabric mats with a standard structural epoxy resin. SEM analysis of recycled fibre non-woven fabric mats This analysis aims to characterise the morphology and degree of cleanliness of the fibres through a Scanning Electron Microscope (SEM) analysis. The advantages offered by this instrument are considerable and clearly explain why it is used: high resolution, high magnification and a wide depth of field. These characteristics allow for an accurate visualisation of the fibres present in the non-woven fabric samples; thanks to the depth of field, it is possible to analyse the surfaces of the fibres at different distances from the focal point. The material supplied consists of two non-impregnated recycled carbon non-woven fabric mats, with a weight per unit area of 200 g/m² and 1000 g/m². The analysed areas, approximately 9 cm² in size, were randomly selected from the non-woven fabric mats. Fig. 3 shows the areas observed at 150x, 2000x, and 4000x magnifications. Although the fibres appear to be distributed almost randomly, a certain amount of them, estimated between 5% and 20% depending on the observation area, group together in bundles with preferential orientations. Furthermore, the same fibre density is observed regardless of the weight per unit area considered. Higher magnifications allow to observe the excellent level of cleanliness of the recycled fibres, achieved thanks to the innovative, entirely mechanical recycling process [20]. Only small amounts of residual material, likely deriving from A R ESULTS AND DISCUSSION

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