English Abstract
Topics on the Radiation Induced Degradation of Elastomers

Masayuki ITO
Advanced Research Institute for Science and Engineering, Waseda University, Shinjuku-Ku, Tokyo, Japan
Nippon Gomu Kyokaishi,(2009),82(5),233-239 General Review in Japanese

Nine kinds of ethylene-propylene-diene elastomer (EPDM) were irradiated under low dose rate (0.33 kGy/h) at room temperature that is the reference condition. As the short time irradiation condition, two conditions shown below were studied.
1) Irradiation of 4.2 kGy/h in 0.5 MPa oxygen at room temperature.
2) Irradiation of 5.0 kGy/h in air at 70 .
It was found out that two methods mentioned above were available as time accelerated irradiation conditions on the view point of changes in mechanical properties. Heat resistant fluorine-containing elastomer did not have radiation resistance. The compounding of EPDM for heat resistance did not have radiation resistance. There was no correlation between heat resistance and radiation resistance. The synergistic relationship between heat and radiation was found out and the coefficient of synergism was proposed to express the degree of synergism. The energy transfer from polymer to antioxidant reagent during irradiation has an important role in radiation induced degradation of elastomers.

Degradation by Irradiation, Ethylene-propylene Elastomer, Time Accelerated Irradiation Method, Modulus-ultimate Elongation Profile, Synergistic Relationship between Heat and Radiation, Energy Transfer