Appraisal of the current standards for stress relaxation measurements in compression for rubbers

Birley, A. W.; Fernando, Kamal P.; Tahir, Mohammed

doi:10.1016/0142-9418(86)90009-7

Cited by 11 publications

(1 citation statement)

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“…For seal materials, the property of paramount interest is the sealing force, and the experimental approach most closely related to this property involves compression stress-relaxation (CSR) measurements [9][10][11]. Stress-relaxation in general results from a combination of socalled physical relaxation processes and chemical effects [12-1 4].…”

Section: Introductionmentioning

confidence: 99%

Methods for Predicting More Confident Lifetimes of Seals in Air Environments

Gillen

Celina

Keenan

2000

Rubber Chemistry and Technology

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We have been working for many years to develop improved methods for predicting the lifetimes of polymers exposed to air environments and have recently turned our attention to seal materials. This paper describes an extensive study on a butyl material using elevated temperature compression stress-relaxation (CSR) techniques in combination with conventional oven aging exposures. The results initially indicated important synergistic effects when mechanical strain is combined with oven aging, as well as complex, non-Arrhenius behavior of the CSR results. By combining modeling and experiments, we show that diffusion-limited oxidation (DLO) anomalies dominate traditional CSR experiments. A new CSR approach allows us to eliminate DLO effects and recover Arrhenius behavior. Furthermore, the resulting CSR activation energy (EJ from 125°C to 70"C is identical to the activation energies for the tensile elongation and for the oxygen consumption rate of unstrained material over similar temperature ranges. This strongly suggests that the same underlying oxidation reactions determine both the unstrained and strained degradation rates. We therefore utilize our ultrasensitive oxygen consumption rate approach down to 23°C to show that the CSR E~likely remains unchanged when extrapolated below 70°C, allowing very confident room temperature lifetime predictions for the butyl seal.

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Section: Introductionmentioning

confidence: 99%