THERMALLY AND HYGROTHERMALLY AGING-INDUCED PROPERTIES AND SERVICE LIFE PREDICTION OF EPDM

초록

EPDM is recognized for its outstanding flexural resistance, resilience, low-temperature performance, and chemical stability, making it suitable for applications in the automotive, sealing, and waterproofing industries. However, a key challenge for this type of rubber-based compound is its susceptibility to thermal, mechanical, or oxidative stress-ors, even under standard operating conditions. Consequently, accurately predicting the service life of these materials is critical to ensure their reliability in practical applications. We propose an accelerated aging methodology to estimate the lifespan of EPDM under thermal and hygrothermal environments. Accelerated thermal aging tests were performed at 70, 80, and 100 degrees C. For hygrothermal conditions, the tests were conducted at 23, 70, and 80 degrees C, with relative humidity levels between 50 and 95%. In both cases, the exposure durations varied from 22 to 672 h. Properties such as tensile strength, elongation at break, tear strength, compressive strength, and hardness, specific gravity, and X-ray photoelectron spectroscopy analysis of the rubber were systematically studied before and after aging. Nevertheless, using the Arrhenius, Peck, and Luo, Wu, and Wu models, shelf life was predicted from the laboratory-based aging data, with a compression set at 25% selected as the failure criterion. It was observed that hygrothermal conditions had a more significant effect on deterioration than thermal aging alone. Thus, this approach provides a valuable framework for assessing the durability of polymeric materials, instilling confidence in their application under specified service conditions.

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