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This work is focused on the mechanical characterization and fracture surfaces analysis of thermosetting polymers reinforced with short, randomly oriented, recycled carbon fibres (rCFs). This work aims at evaluating fibre/matrix adhesion between recycled CFs-reclaimed via pyrolysis followed by controlled oxidation of the pyrolytic char-and different polymer matrices, namely epoxy and vinyl ester resins. The latter is the main focus in this work, being amongst the most widely used thermosetting resins in SMC processes, which are the typical target for short rCFs. The evaluation of the properties of this new recycled carbon fibre reinforced polymer (rCFRP) has been via thermogravimetric analysis, dynamic mechanical analysis, stress/strain tests in tensile mode, and a subsequent analysis of the fracture surfaces by means of images analysis obtained by macrophotography, Optical Microscopy and Scanning Electron Microscopy. The comparison amongst the results allowed to evaluate the influence of the polymer nature and of the adhesion quality between fibres and polymeric matrix, mainly on the mechanical properties of the rCFRPs.

This work focuses on the optimization of pyro-gasification process of carbon fiber reinforced polymers (CFRPs) with the aim of recovering carbon fibers (CFs) with properties suitable for the production of new more sustainable composites with high performances. In particular, the pyro-gasification process is carried out on cured CFRPs panels based on both epoxy (EC) and vinyl ester (VC) matrices, which are the two most used resins for CFRPs. The matrix degradation is evaluated via sample's weight loss measurement and the recovered CFs obtained after different time of treatment are analyzed to identify convenient pyro-gasification conditions to avoid damaging of the recovered CFs. The obtained results highlight the importance of the thickness of the composites to be treated for the identification of the more suitable pyro-gasification conditions.

The present work presents the evaluation of the performance of single carbon fibers after pyro-gassification treatment in different gasification conditions, i.e. 500°C for 30' and 60', and 600°C for 20', in order to evaluate the intrinsic fiber properties that might contribute to the overall composite behavior when re-impregnated with a polymeric matrix. Such investigation, carried with different analytic techniques such as Raman spectroscopy, XRD diffractometry, SEM Microscopy with EDX atimic mapping and finally mechanical tensile test carried out on single fibers, proves that convenient pyro-gassification conditions might lead to recovery of carbon fibers with properties not far from the pristine ones. While some further tuning of the gasification condition might still be required, 500°C proved to be the optimal temperature for treatment, where the structure and morphology are practically untouched and mechanical properties are well comparable with pristine fibers in terms of Young's Modulus with just a slight drop in ultimate properties.