Synthesis of Reactive Antioxidant and Its Influence on the Thermal-Oxidative Stability of Nylon 6

To enhance the efficiency and durability of hindered amine antioxidants in improving the thermo-oxidative aging resistance of polyamide 6 （PA6）, a reactive hindered amine antioxidant, 4-（4,6-bis（2,2,6,6-tetramethylpiperidin-4-yl）amino）-1,3,5-triazin-2-yl）oxybenzoic acid （TAPA）, was synthesized and grafted onto PA6 via a melt reactive extrusion process. The structure of TAPA and the grafted PA6 （PA6-g-TAPA） were characterized by FT-IR, ¹H-NMR, and HRMS analysis. The thermo-oxidative aging behaviors of commercial PA6, PA6 containing a small-molecule antioxidant and PA6-g-TAPA were comparatively investigated in terms of functional group content, crystallization characteristics, mechanical strength, and color difference. Results indicate that TAPA can be successfully grafted onto the PA6 chain and significantly improve the thermo-oxidative stability of PA6 by effectively suppressing carbonyl formation and chain scission. Consequently, the deterioration of mechanical properties and yellowing were alleviated. Compared with conventional additive-type antioxidants, the grafted reactive antioxidant exhibited a more persistent anti-aging performance and longer service life under prolonged aging conditions, showing great potential for application in the weather-resistant modification of PA6 materials.