Study of Aging and Degradation of Fluoroelastomers in HPHT Sour Conditions Under Acceleration Testing

Abstract Fluoroelastomers are widely used in high-pressure, high-temperature (HPHT) oil and gas downhole applications due to their resistance to aggressive chemical environments. This study investigates the aging and degradation behavior of laboratory-formulated tetrafluoroethylene-propylene (FEPM) rubbers subjected to HPHT sour (H2S) conditions through accelerated aging tests at 200°C, 225°C, and 250°C. Mechanical testing revealed that tensile strength and modulus at 25% and 50% strain declined significantly with aging time and temperature, indicating early onset degradation. Dynamic Mechanical Analysis (DMA) showed reductions in the glass transition temperature (Tg), suggesting crosslink density loss. Solid-state 13C CP-MAS NMR confirmed rapid decline of the Triallyl Isocyanurate (TAIC) carbonyl peak near 150 ppm, supporting the observation of early-stage crosslinking breakdown. Fourier-transform infrared (FTIR) analysis further evidenced carbonyl degradation. Combining thermal, mechanical, spectroscopic, and analytical characterization, the degradation mechanism was elucidated and the material’s service life was estimated using the Arrhenius approach per ISO 23936-2 guidelines. The findings offer critical insights into FEPM behavior in sour gas environments and support the development of more robust sealing materials for extreme HPHT sour applications.