Combined effect of hindered amine light stabilizer and antioxidants on photodegradation of poly (vinyl chloride)

Casted PVC films with hindered amine light stabilizer (HALS) and antioxidants are photo-irradiated for 400-h and the process of photodegradation is characterized by color differences, ultraviolet-visible (UV-vis) spectroscopy, Fourier transformation infrared (FT-IR) spectroscopy and viscosity-average molecular weight (Mη). When added to PVC separately, hindered amine derivate (T770) and phenol antioxidant (1076) both have little effect on the dehydrochlorination and oxidation of PVC films. In PVC films with T770/1076, the extension of shorter polyenes is retarded during photo-irradiation of 400-h. The extension of longer polyenes is well retarded from 0-h to 200-h. T770/1076 has only a little effect on the anti-oxidation of PVC films from 0-h to 400-h. The p-phenylenediamine antioxidant (4010NA) and 2-Mercapto benzimidazole (MB) both accelerate the photodegradation and crosslinking of PVC films. However, there is no crosslinking in PVC with T770/4010NA and PVC with T770/MB and the degradation of PVC films is weakened. This phenomenon means the light stabilizer T770 protects antioxidants (4010NA and MB) from photo-irradiation and antioxidants can play a positive role in the antioxidative effect.