Effect of Dose Rate on Degradation Behavior of Insulating Polymer Miaterials

The dose rate effect on the mechanical and electrical properties of representative insulating and jacket materials has been studied. Crosslinked polyethylene (XLPE),thylene ethylene-propylene terpolymer (EPDM), and some chlorine containing polymeric materials are irradiated in air at several dose rates. XLPE degrades significantly at lower dose rates, but EPDM shows opposite dose rate dependency to XLPE. Dose rate effect is interpreted as a competition between the dissolution and diffusion of oxygen into the sample and the oxidation reaction by irradiation. Ingredient compounding in chlorine containing polymeric materials may depress the dose rate effect.