Mechanically Robust Poly (Metaphenylene Isophthalamide) Fibers Enhanced From the Recycling of Heterocyclic Para‐Aramid Fibers via Deprotonation and Blending Strategies

ABSTRACT Poly (metaphenylene isophthalamide) (PMIA) fiber has excellent heat resistance and flame‐retardant ability, but its mechanical properties are poor due to its own structure. Therefore, it is of great significance to improve the mechanical properties of fibers to expand their application range. Meanwhile, a large amount of waste aramid fibers generated during the production process are mishandled, resulting in the waste of valuable resources as well as serious environmental pollution. In this study, heterocyclic para‐aramid fibers were treated by deprotonation to obtain heterocyclic para‐aramid nanofibers, which were combined with PMIA fibers as a reinforcing phase. The composite fibers presented superior mechanical properties through wet spinning and stretching phases. The results showed that when the addition of HANF was 0.4%, the tensile strength and elongation at break of HANF/PMIA composite fibers were increased by 86.28% and 48.48% respectively, compared with PMIA fiber. Compared to most of the current studies on nano‐filler reinforced fiber, this work has the advantages of low addition of nano‐filler and significant strengthening effect. It provides a feasible and cost‐effective approach for the recycling of heterocyclic aramid fiber.