A novel carbon nanohorn-based intumescent multilayer nanocoating on cotton fabrics: thermal degradation kinetics, flammability and flame-retardant mechanism

Abstract

Creating eco-friendly flame retardants (FRs) that are highly effective for textiles while requiring minimal quantities is crucial for both human well-being and environmental conservation. Traditionally, halogen FRs have been the mainstay in this field. Yet, due to their harmful impacts on both human health and the environment, there is a growing demand to discontinue their use. Herein, in this work, a novel eco-friendly intumescent-based flame retardant for cotton fabrics, consisting of ammonium polyphosphate (APP), single-walled carbon nanohorns (SWCNHs), and melamine (MEL) was explored. The addition of SWCNHs demonstrated a clear synergistic effect with APP and MEL in enhancing the flame retardancy of cotton fabrics. After four spraying cycles, the treated cotton fabric ASM4 demonstrated outstanding flame retardancy and self-extinguishing properties. Additionally, its LOI value could reach 24.1 ± 0.1% and the damage length dropped to 4.6 ± 0.2% cm from 30.0 ± 0.1% cm for the pristine cotton fabric, while preserving its original morphology with partial carbonization. The pHRR and THR of ASM4 were dramatically decreased by 90% and 51%, respectively in the cone calorimeter test. Moreover, investigating the thermal degradation kinetics of treated cotton fabric and the physicochemical properties of the char residues revealed the crucial influence of SWCNHs on improving the flame resistance of cotton fabrics. The incorporation of SWCNHs improved both the thermal stability and the degree of graphitization of the char layer, which served as a protective barrier. This barrier efficiently blocked the release of volatile combustible substances while allowing for the emission of nonflammable gases. This work provides a theoretical basis for the feasible application of SWCNHs in intumescent FRs.