Synthesis of a novel triazine N-alkoxyamine for simultaneously enhancing the flame retardancy and UV aging resistance of intumescent flame-retardant polypropylene

Polypropylene (PP) is highly flammable and prone to ultraviolet (UV) aging, limiting its durability. Conventional intumescent flame retardants (IFR) require high loadings (20-30 wt%), which deteriorate mechanical properties. Herein, a low-basicity N-alkoxyamine compound (CDMP) is designed as a multifunctional synergist for IFR-modified PP. With only 0.3 wt% CDMP and 19.7 wt% IFR, the composite achieves a limiting oxygen index (LOI) of 33.0% and a vertical burning (UL-94) V-0 rating, while reducing total heat release (THR) and total smoke production (TSP) by 22.2% and 37.6%, respectively. After 120 h UV exposure, the composite shows minimal surface damage and a lower carbonyl index growth rate (87.2% of neat PP), indicating enhanced UV resistance. Meanwhile, elongation at break and impact strength are significantly improved compared to PP/IFR. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis reveals that CDMP generates nitroxyl radicals, which quench free radicals during both photo-oxidation and combustion. This synergy between IFR and CDMP enables simultaneous enhancement of flame retardancy, UV stability, and mechanical performance in PP.