Upcycling p-Aramid Waste into Universal Antidripping Aramid Nanofiber Coatings for Future Mobility Interior Plastics

Para-aramid (p-aramid) is a high-performance polymer that is exceptionally mechanically, thermally, and chemically stable. However, its thermal protective effects have received less attention than their well-documented mechanical properties. Herein, we present a sustainable and nontoxic aramid nanofiber (ANF) coating that enhances the antidripping performance of various automotive interior plastics. From a sustainability perspective, p-aramid waste can be upcycled into ANF coating solutions. Additionally, ANFs were successfully dispersed in ethanol (EtOH) through the use of suspension rheology, with flame protection achieved by uniformly coating the ANFs onto five representative automotive plastics: polyethylene, polypropylene, poly(ethylene terephthalate), polycarbonate (PC), and poly(methyl methacrylate) without surface treatment. The ANF coating endowed each substrate with antidrip and self-extinguishing properties. In terms of flame retardancy, the ANF coating increased the limiting oxygen index (LOI) of all tested plastics. Among them, PC exhibited an LOI improvement of 6.4% (from 22.4 to 28.8%), exceeding the threshold for self-extinguishing plastics. The thermally infusible ANF coating formed a dense char layer with a high char yield of 42.1% during combustion, which serves as an effective antidripping barrier. Hence, the use of a universal ANF coating provides an effective strategy for suppressing the flammability of various types of interior plastics and mitigating fire hazards for future mobility applications.