Electron Radiation Effects on the Electrical and Mechanical Properties of Polypropylene

Capacitor-grade polypropylene film was irradiated in air with a 1 MeV electron beam to different doses up to 108 rads and the post-irradiation effects on the electrical and mechanical properties of the film were evaluated. The electrical properties included the 60 Hz a. c. breakdown voltage, dielectric constant and dissipation factor. The dielectric constant and dissipation factor were obtained at five frequencies ranging from 50 Hz to 10 kHz. The tensile properties comprised the Young's modulus, elongation-at-break and tensile strength. While the electrical and tensile properties were evaluated at room temperature, the dynamic mechanical properties were determined at a frequency of 110 Hz in a temperature range of 12°C to 120°C. The results obtained indicate that while the electrical properties remain relatively stable at doses up to 107 rads, the mechanical properties exhibit a steady decline even at lower dose levels.