Résumé
Carbon fibre reclaiming and reuse is both an environmentally and economically fruitful endeavour. The reuse of pyrolysis reclaimed carbon fibres (RCF) in meaningful quantities for high performance parts is promising. However, the harmfulness of the reclaiming process to the mechanical properties of fibres and their adhesion capabilities with polymeric matrix must be investigated. This paper studies the mechanical and surface properties of pyrolysis RCF in comparison with sized and de-sized fibres to assess their potential for reuse. Tensile mechanical properties of these three fibre types were evaluated via micromechanical tensile testing of single fibre samples. RCF show a minor diminution in tensile strength and unchanged elastic modulus which makes these intrinsic mechanical properties suitable for reuse in composite parts. The morphology of the fibre surfaces were analysed using scanning electron microscopy and atomic force microscopy. The scans show clearly different morphologies. RCF present polymeric residues as well as smooth areas very similar to de-sized fibres. Atomic force microscopy was also used to measure the roughness of fibre surfaces. The mean roughness of RCF surfaces was higher than that of de-sized fibres but lower than that of sized fibres. In that context, the residual polymer might be a contributor to better interfacial properties between the fibre and the matrix. Tensiometric tests were carried out to determine fibre surface energy. The RCF showed higher surface energies than de-sized fibres suggesting better adhesion. However, this finding did not transfer to better cohesion between RCF and the polymer matrix. Indeed, in IFSS testing both RCF and de-sized fibres showed similar interfacial shear strength values. The outcomes of this work contribute to the optimisation of the reclaimed carbon fibre re-use in composites. In particular, they highlight the necessity for a surface treatment on RCF to enhance fibre/matrix adhesion and thus composite mechanical properties.