Toward More Sustainable High-Performance CFRPs by Coupling Bio-based Epoxy Resins and Recycled Carbon Fibers

Short carbon fiber reinforced polymers (SCFRPs) containing commercial (C-CFs), washed commercial (wC-CFs), and recycled (R-CFs) fibers and two bio-based epoxies, diglycidyl ether of vanillyl alcohol and diglycidyl ether of gastrodigenin, as well as a commercial BPA-derived resin, were produced. R-CFs were reclaimed by pyro-gasification of CFRP in a semi-commercial pilot plant. Composites display CF contents ≥ 70 wt.%, thermal stability ≥ 340 °C, and glass transition temperatures (Tgs) ≥ 128 °C (loss moduli) as well as tensile moduli at least one order of magnitude higher than neat epoxies. Both bio-based formulations exhibited strong affinity with C-CFs and R-CFs, generating composites with a slight decrease in tensile mechanical performance compared to BPA-based analogues. Furthermore, SCFRPs with wC-CFs confirmed that deficiencies of R-CF containing SCFRPs could be mainly ascribed to the lack of sizing. Nevertheless, they still display performances suitable for non-structural applications where lightweight and low-cost materials are required, while achieving overall “net” sustainability percentages above 90 wt.%.