Degradation Mechanism of Ethylene-propylene-diene Terpolymer by Ozone in Aqueous Solution

Abstract

The degradation of ethylene-propylene-diene terpolymer (EPDM) in ozone water has been investigated. The surface of EPDM specimen degraded rapidly in ozone water. It showed adherence after ozone water treatment, since the polymer near the surface decomposed. From Fourier transform infrared (FT-IR) spectroscopy, the aggregation structure near the surface of EPDM treated with ozone in aqueous solution was different from that treated with ozone in gas phase. This may be due to that the degradation of EPDM by ozone in aqueous solution was initiated by hydroxyl radical, which was generated by self-decomposition of ozone. Through nuclear magnetic resonance (NMR) spectroscopy, the detected structures from degraded EPDM after ozone water treatment agreed with the most probable structures, which may be produced by ozone water treatment. It was concluded that the degradation of EPDM proceeded in ozone water, regardless of its good ozone resistance in air, because hydroxyl radical caused the decomposition of EPDM, which was initiated from proton abstraction from saturated hydrogen carbon linkage of EPDM main chain.