Effect of Alteration of Antioxidant by UV Treatment on the Dielectric Strength of BOPP Capacitor Film

The effect of altered products of the antioxidant by UV irradiation on dielectric breakdown strength of metallized biaxially-oriented polypropylene (BOPP) capacitor film was studied. Results from Weibull statistical analysis show that an optimal UV exposure level of ~3.4 J/cm² (200-400 nm) increases the breakdown strength at 5% probability by ~20%. As indicated by UV spectroscopic analysis, the antioxidant in BOPP was consumed almost entirely to form 2,6-di-tert-butyl-p-benzoquinone (2,6-DTB-PBQ). Density functional theory computations indicate that this compound is electronegative, which probably accounts for the increased dielectric strength.