The antioxidant mechanism of hindered phenolic antioxidants bonded with para bridge groups in PA6

The correlations between the antioxidant activity and hindered phenolic antioxidants bonded with para bridge structures in polyamide 6 (PA6) were studied by comparing the antioxidant properties of three hindered phenolic antioxidants bonded with different bridging groups. The antioxidant properties of the pure PA6 and stabilized PA6 were investigated in terms of mechanical properties, rheological properties, crystallization properties, chemical structure, and the migration resistance of antioxidants. The radical scavenging activity and capacity of hindered phenolic antioxidants were also compared. The results showed that the hindered phenolic bonded with the aromatic ring exhibits the best activity and capacity in scavenging radical and the best migration resistance in PA6. Therefore, the tensile strength of PA6/HPAP remains at 117 % of the unaged sample after 12 days of thermal oxygen aging at 150 °C, and the notch impact strength of PA6/HPAP remains at 68 % of the unaged sample. The mechanical properties of PA6/HPAP are comparable to PA6/1098 (a commonly used commercial antioxidant in PA) after 12 days of thermal oxygen aging. The mechanism of the hindered phenolic antioxidants bonded with para bridge structure in scavenging PA6 free radicals and inhibiting the aging of PA6 macromolecular chains was explored in this article.