Methods for Predicting More Confident Lifetimes of Seals in Air Environments

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Description

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 ... continued below

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31 p.

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Celina, M.; Gillen, K.T. & Keenan, M.R. March 5, 1999.

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This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 12 times . More information about this article can be viewed below.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Albuquerque, NM, and Livermore, CA (United States)
    Place of Publication: Albuquerque, New Mexico

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Description

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 (E{sub a}) 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{sub a} likely remains unchanged when extrapolated below 70 C, allowing very confident room temperature lifetime predictions for the butyl seal.

Physical Description

31 p.

Notes

OSTI as DE00004252

Medium: P; Size: 31 pages

Source

  • Journal Name: Rubber Chemistry and Technology; Other Information: Submitted to Rubber Chemistry and Technology

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  • Report No.: SAND99-0553J
  • Grant Number: AC04-94AL85000
  • Office of Scientific & Technical Information Report Number: 4252
  • Archival Resource Key: ark:/67531/metadc681680

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  • March 5, 1999

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  • July 25, 2015, 2:20 a.m.

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  • April 12, 2017, 1:11 p.m.

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Celina, M.; Gillen, K.T. & Keenan, M.R. Methods for Predicting More Confident Lifetimes of Seals in Air Environments, article, March 5, 1999; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc681680/: accessed September 19, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.