Upcycling <scp>CFRP</scp> waste for aerospace applications: Recovery of carbon fibers, <scp>CNT</scp> growth, and composite fabrication

Abstract In this study, carbon fiber (CF) was recovered from carbon fiber reinforced polymer (CFRP) composite waste using microwave‐assisted chemical recycling technique, utilizing a combination of acetic acid and hydrogen peroxide in equal proportions. The mechanical properties of the recovered carbon fiber (RCF) were successfully improved by growing carbon nanotubes (CNTs) on its surface using microwave irradiation (720 W). Ferrocene was used as a catalyst for growing CNTs. The scanning electron microscopy (SEM) analysis suggested hair‐like dense growth on the RCF surface. The Raman spectral analysis indicated the existence of D + D', G' peaks and a decline in I D /I G values by 0.9 for CNT‐grown recovered carbon fiber (CNT_RCF) in comparison to RCF, confirming the CNT growth. The CNT‐grown RCF was subsequently used to develop composites. The CNTs facilitated the improved wettability of RCF and acted as an anchorage point at the RCF/epoxy interface, resulting in improved mechanical properties. Compared to RCFRP composite, the mechanical characteristics of developed composites such as interlaminar shear strength (ILSS), ultimate tensile strength (UTS) and interlaminar fracture toughness (ILFT) of CNT‐grown recovered carbon fiber (CNT_RCFRP) composite were increased by 8%, 29%, and 19%, respectively. Highlights The CF was recovered from CFRP waste using the MACR technique. The CNT was successfully grown on RCF using microwave irradiation. Mechanical properties of RCF were successfully upcycled to VCF. The ILFT of CNT_RCFRP composite enhanced by 19% compared to RCFRP. The contact angle was correlated with the ILSS and UTS of the resulting composites.