Recycled carbon fiber potential for reuse in carbon fiber/PA6 composite parts

Pyrolysis reclaiming is the most promising process to treat high volumes of composite waste with an advantageous carbon footprint. This paper aims to compare pyrolysis reclaimed carbon fibers (RCF) to virgin sized fibers (VF) and de-sized fibers (VFT) in their capability to bond to a polyamide 6 matrix. Micromechanical tensile testing of single fiber samples of the three fiber types was conducted. A minor reduction in tensile strength and an unchanged elastic modulus of the RCF compared to VF was observed. Scanning electron microscopy and atomic force microscopy scans were used to evaluate the morphology of the fibers. To evaluate the surface energy of the fibers, tensiometric testing was conducted. RCF showed a better adhesion capability compared to VFT through higher total surface energy. Moreover, X-ray spectrophotometry scans highlighted a higher proportion of functional groups at the RCF surface compared to VFT. Finally, pull-out tests underlined a decrease of the interfacial shear strength of RCF and VFT by 35% compared to VF. Overall, this study's results further the understanding of the impact of the pyrolysis reclaiming process on RCF mechanical and adhesion properties.