Valorization of Discarded Para‐Aramid Fibers for Synergistic Enhancement of Poly(m‐Phenylene Isophthalamide) Composites

ABSTRACT Poly(m‐phenylene isophthalamide) (PMIA) fibers have been widely adopted across various fields due to their outstanding heat resistance and flame retardancy. However, the inferior mechanical properties of PMIA fibers adversely affect the service life of products manufactured from them. Meanwhile, the improper disposal of substantial waste para‐aramid fibers from production entails both the wasteful loss of valuable resources and serious environmental consequences. In this work, we demonstrated a strategy to enhance the properties of PMIA fibers by blending its solution with aramid nanofibers (ANF) derived from waste para‐aramid via deprotonation. A minimal amount of ANF (0.15% of PMIA mass) was able to improve the tensile strength and elongation at break of PMIA/ANF fibers by 76.71% and 78.15%, respectively, compared to pristine PMIA fibers. Nano‐composite fibers possessed not only superior mechanical properties but also exhibited enhanced heat resistance and flame retardancy. The glass transition temperature and thermal shrinkage rate at 320°C for the composite fiber with 0.15% ANF were 322°C and 5.83%, respectively, whereas the corresponding values for the pristine PMIA fiber were 318°C and 7.67%. The proposed method establishes a synergistic strategy for enhancing PMIA fibers and valorizing waste para‐aramid, contributing to both material advancement and a circular economy.