Degradation of Irgafos 168 and migration of its degradation products from PP‐R composite films

Food contact materials contain non‐intentionally added substances from degradation, and reaction processes could rise food safety problems. Three polypropylene random copolymer composite films were prepared by extruding the polypropylene random copolymer matrix with Irgafos 168, Irgafos 168 and nanocopper, Irgafos 168 and KH550 modified nanocooper, respectively. To evaluate the degradation behaviors of Irgafos 168, the films were treated by UV irradiation, microwave treatment, sunlight exposure, placed in different oxygen concentration conditions, suffered the extrusion process, and high temperature. Migration test was conducted at 20°C, 40°C, and 70°C with films tested in food simulant. GC‐MS was adopted to determine the concentration of Irgafos 168 and its two degradation products, 2,4‐di‐tert‐butylphenol (DP1) and tris (2,4‐di‐tert‐butylphenyl) phosphate (DP2). UV irradiation significantly accelerated the degradation of Irgafos 168 compared with other treatments; DP1 and DP2 increased to maximum value at 24 hours and decreased afterwards, simultaneously. The introduction of nanocopper notably promoted DP1 generation after extrusion whereas suppressed DP2 generation which also caused a higher degradation rate of Irgafos 168 and sharp decrease of DP1 under microwave treatment, sunlight exposure, and high temperature treatment. No significant difference between the effects of nanocopper and KH550 modified nanocopper on degradation of Irgafos 168 was found. For the migration test, the introduction of nanocopper inhibited the migration of Irgafos 168 and DP2 whereas promoted the migration of DP1. No significant difference between the introduction of nanocopper and KH550 modified nanocopper on migration of Irgafos 168 and DP1, DP2 was found.