Prevention of degradation of γ-irradiated EPDM using phenolic antioxidants
The mitigation of oxidative degradation under γ-irradiation promoted by eight commercial antioxidants: Ethanox 330, Hostanox O3, Irganox 1010, Topanol OC, Ionox 220, Santonox R, Santowhite, Cyanox 2246 loaded onto ethylene-propylene terpolymer at the concentration of 0.5 phr in respect of a pristine polymer was studied. The polymer samples were exposed to various doses up to 500 kGy. The kinetic parameters of oxidations: oxidation induction times, onset oxidation temperature, oxidation rates were evaluated by CL measurements. They validated the differences in the stabilisa-tion activities by limitation of the oxidation gradient. The high efficiency of some of the antioxidants studied, such as Ionox 220 and Santowhite, ensured the delay in degradation even at a high irradiation dose (500 kGy). For the environments with γ-radiation exposure, a relevant sequence in the increasing protection efficiency could be established: Topanol OC; Hostanox O3; Irganox 1010; Cyanox 2246; Santonox R; Ionox 220; Santowhite. The FT-IR spectra were recorded for the calculation of the radiochemical yields resulting from the modifications occuring in the concentrations of oxygenated structures. The accumulations of hydroxyl- and carbonyl-containing products were calculated to evaluate the irradiation effects in EPDM-based products during a severe accident. The options for EPDM stabilisation are discussed based on chemiluminescence and FTIR analyses.
Key wordsEPDM radiation degradation oxidation stabilisation FT-IR chemiluminescence
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