A study of gamma radiation effects on PVC compounds

Molecular structural damage caused by gamma radiation in PVC (polyvinyl chloride) compounds is investigated as it is reflected in changes of the dielectric properties of the system. Three PVC compounds were selected containing different amounts of plasticizer to change their stiffness from rigid to flexible. These compounds were exposed to 10⁵, 10⁶, and 10⁷ rad of gamma rays coming from the impact of 8 MeV electrons on gem stones. The dielectric properties of these compounds were determined at 25°C between 250 kHz and 70 MHz. At the two higher radiation levels significant changes in the dielectric constant, loss tangent, and AC conductivity were noted. The analysis suggests that plasticized PVC compounds may be useful electrical insulation compounds under moderate gamma radiation conditions