Sustainable PA6 Composites from Recycled Carbon Fiber Thermoplastics for Mechanical and EMI Applications

The growing demand for sustainable solutions in advanced composite materials has driven interest in reusing carbon fiber-reinforced thermoplastic (CFRT). This study investigates the rheological, mechanical, thermal, electrical, and electromagnetic properties of polyamide 6 (PA6) composites reinforced with recycled CFRT waste. The composites were prepared by the extrusion process with different ground CFRT contents (10 and 20 wt %). Differential scanning calorimetry (DSC) revealed that the presence of carbon fibers acts as an effective heterogeneous nucleating agent, increasing the crystallization temperature and the degree of crystallinity. Mechanical characterization demonstrated significant improvements, with the elastic modulus and ultimate tensile strength increasing by up to 80% and 69%, respectively, while strain at break was reduced due to the restriction of polymer chain mobility and stress concentration around fiber-matrix interfaces. Impact strength improved by 53% at higher ground CFRT contents, driven by energy dissipation mechanisms such as fiber pull-out and crack deflection. Electromagnetic characterization indicated promising shielding effectiveness (SET), reaching up to 16 dB in the X-band, with absorption-related mechanisms presented. The composites exhibit a desirable combination of mechanical performance and electromagnetic interference (EMI) shielding capabilities. These findings underscore the potential of CFRT-reinforced PA6 composites as sustainable, high-performance materials for applications requiring mechanical and electronic requirements.