A critical study on interfacial modification and scalable processing of high-performance regenerated carbon fiber reinforced thermoplastic composites from waste CFRP

Abstract

The substantial annual generation of carbon fiber–reinforced polymer (CFRP) waste from key industries, including sporting goods and aerospace, poses a serious environmental challenge, as most of this material is disposed of via landfilling. This study demonstrates a scalable and industrially viable process to fabricate high-performance carbon–reinforced thermoplastic composites (CFRTP) from regenerated carbon fibers (rCF) to address this issue. The rCF were recovered from discarded bicycle frames and wind turbine blade spars via microwave-assisted pyrolysis, subsequently surface-modified with a novel modifier, and compounded with polyamide 66 (PA66) using a custom-designed high-temperature dispersion kneader. Experimental results revealed that an optimal 5 wt.% surface modification yielded comprehensive mechanical enhancements over unmodified composites, including increases in tensile strength (+ 10.0%), Young’s modulus (+ 22.8%), flexural strength (+ 8.3%), flexural modulus (+ 13.1%), and impact strength (+ 23.8%). Notably, the modified rCF composites also outperformed a benchmark commercial composite (reinforced with virgin carbon fibers) in tensile strength (by 20.3%) and flexural strength (by 21.4%). Scanning electron microscopy analysis attributed this superiority to enhanced fiber-matrix bonding and greater fiber length retention, a direct result of the low-shear nature and high-dispersion efficiency of the kneader process. This work validates a robust pathway for the high-value recycling of CFRP waste, offering a sustainable solution for producing high-performance composites with strong potential for industrial applications in the automotive and sporting goods sectors.