A viable strategy to recycle post-used carbon fiber thermoset composites as a multi-functional filler for PP composites

Abstract

The correct destination of this post-used of carbon fiber (CF) reinforced epoxy composites, is considered noble since their manufacturing process involves high costs and advanced technologies. This work aimed to study the feasibility of mechanical recycling of CF/epoxy composites for nobler applications, such as non-structural internal components, antistatic packaging, or electronics housings. The CF/epoxy residues (CFRPres.) were collected from parts of the aerospace industry, selected, and ground, followed by granulometric separation. Then, the CFRPres. particles were incorporated as filler and/or partial reinforcement in a polypropylene (PP) matrix to obtain a new thermoplastic composite using double-screw extrusion processing, followed by hot compression molding to obtain standardized specimens. The quality of the composites obtained was evaluated through mechanical tests (tensile test, Izod impact strength, and Shore D hardness), thermal (differential scanning calorimetry), electric (impedance spectroscopy, electromagnetic), and morphological characterization (scanning electron microscopy). The addition of 30 wt% of CFRPres. in the PP matrix increases the electrical conductivity by seven orders of magnitude and exhibits semiconductor behavior, and increases 168% in the elastic modulus. As for the electromagnetic properties, increasing the content of residues in the composites also occurs a substantial increase in the relative permittivity. In addition, the development of composites from the incorporation of residues from the aerospace sector proved viable in applications where the impact strength, rigidity, and hardness are crucial, even for the high content of residues aggregate.