Synthesis and antioxidant capacity of a C12-naphthylamine antioxidant in polyethylene

A C 12 -naphthylamine antioxidant (3,3′-(dodecylazanediyl)bis( N -(4-(naphthalen-2-ylamino)phenyl) propanamide)) was successfully synthesized via Michael addition and amidation reactions. The chemical structure was analyzed by Fourier transform infrared spectra (FTIR), 1 H-nuclear magnetic resonance spectroscopy ( 1 H NMR), and liquid chromatography–mass spectrometry (LC–MS). Thermal stability of C 12 -naphthylamine antioxidant was also examined by differential scanning calorimetry (DSC). The scavenging capacity of antioxidants was investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The efficiency of the antioxidants in thermo-oxidative stabilization of polyethylene (PE) was determined by DSC, FTIR, and tensile testing machine. The results showed that the inhibition percentage of the C 12 -naphthylamine antioxidant was 57.09, the oxidation induction time (OIT) was 157.83 min, and the carbonyl index (CI) was 0.25. In addition, the C 12 -naphthylamine antioxidant had a better antioxidant efficiency in both scavenging test and thermo-oxidative test compared with N -phenyl-2-naphthylamine and N , N ′-di-2-naphthyl-p-phenylenediamine. The result for migration of antioxidants from PE indicated that migration content of C 12 -naphthylamine antioxidant was small.