Thermo-Oxidation Mechanism of Sulfur Vulcanized Ethylene-Propylene-Diene Rubbers Studied by FT-IR and Pyrolysis GC-MS

Abstract

Thermo-oxidized ethylene-propylene-dinen (EPDM) rubbers (sulfur vulcanized) were charac terized by FT-IR spectroscopy and high-resolution pyrolysis-gas chromatography-mass spectro metry (Py-GC/MS). Depth profile of micro FT-IR spectra indicated that carbonyl products were formed more abundantly in the surface area. In addition, saturated and unsaturated carbonyl products formed in the polymer chain were typically observed in the ATR FT-IR spectra. On the basis of the observed spectra, the formation mechanisms of the carbonyl products were discussed. Moreover, it was proved that diene unit was oxidized earlier to yield 5-acetylcyclopentadiene (ACP) which was confirmed by observing the MS spectrum obtained by Py-GC/MS. Finally thermo oxidation mechanism of sulfur vulcanized EPDM was comprehensively discussed.