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Title: Predicting Polymer Degradation and Mechanical Property Changes for Combined Radiation-Thermal Aging Environments

Abstract

Here, a new approach is presented for conducting and extrapolating combined environment (radiation plus thermal) accelerated aging experiments. The method involves a novel way of applying the time-temperature-dose rate (t-T-R) approach derived many years ago, which assumes that by simultaneously accelerating the thermal-initiation rate (from Arrhenius T-only analysis) and the radiation dose rate R by the same factor x, the overall degradation rate will increase by the factor x. The dose rate assumption implies that equal dose yields equal damage, which is equivalent to assuming the absence of dose-rate effects (DRE). A plot of inverse absolute temperature versus the log of the dose rate is used to indicate experimental conditions consistent with the model assumptions, which can be derived along lines encompassing so-called matched accelerated conditions (MAC lines). Aging trends taken along MAC lines for several elastomers confirms the underlying model assumption and therefore indicates, contrary to many past published results, that DRE are typically not present. In addition, the MAC approach easily accommodates the observation that substantial degradation chemistry changes occur as aging conditions transition R-T space from radiation domination (high R, low T) to temperature domination (low R, high T). The MAC-line approach also suggests an avenue formore » gaining more confidence in extrapolations of accelerated MAC-line data to ambient aging conditions by using ultrasensitive oxygen consumption (UOC) measurements taken along the MAC line both under the accelerated conditions and at ambient. From UOC data generated under combined R-T conditions, this approach is tested and quantitatively confirmed for one of the materials. In analogy to the wear-out approach developed previously for thermo-oxidative aging, the MAC-line concept can also be used to predict the remaining lifetimes of samples extracted periodically from ambient environments.« less

Authors:
 [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1465385
Report Number(s):
SAND-2018-8787J
Journal ID: ISSN 0035-9475; 666928
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Rubber Chemistry and Technology
Additional Journal Information:
Journal Volume: 91; Journal Issue: 1; Journal ID: ISSN 0035-9475
Publisher:
American Chemical Society (ACS), Rubber Division
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Gillen, Kenneth T., and Celina, Mathew. Predicting Polymer Degradation and Mechanical Property Changes for Combined Radiation-Thermal Aging Environments. United States: N. p., 2018. Web. doi:10.5254/rct.18.81679.
Gillen, Kenneth T., & Celina, Mathew. Predicting Polymer Degradation and Mechanical Property Changes for Combined Radiation-Thermal Aging Environments. United States. doi:10.5254/rct.18.81679.
Gillen, Kenneth T., and Celina, Mathew. Mon . "Predicting Polymer Degradation and Mechanical Property Changes for Combined Radiation-Thermal Aging Environments". United States. doi:10.5254/rct.18.81679. https://www.osti.gov/servlets/purl/1465385.
@article{osti_1465385,
title = {Predicting Polymer Degradation and Mechanical Property Changes for Combined Radiation-Thermal Aging Environments},
author = {Gillen, Kenneth T. and Celina, Mathew},
abstractNote = {Here, a new approach is presented for conducting and extrapolating combined environment (radiation plus thermal) accelerated aging experiments. The method involves a novel way of applying the time-temperature-dose rate (t-T-R) approach derived many years ago, which assumes that by simultaneously accelerating the thermal-initiation rate (from Arrhenius T-only analysis) and the radiation dose rate R by the same factor x, the overall degradation rate will increase by the factor x. The dose rate assumption implies that equal dose yields equal damage, which is equivalent to assuming the absence of dose-rate effects (DRE). A plot of inverse absolute temperature versus the log of the dose rate is used to indicate experimental conditions consistent with the model assumptions, which can be derived along lines encompassing so-called matched accelerated conditions (MAC lines). Aging trends taken along MAC lines for several elastomers confirms the underlying model assumption and therefore indicates, contrary to many past published results, that DRE are typically not present. In addition, the MAC approach easily accommodates the observation that substantial degradation chemistry changes occur as aging conditions transition R-T space from radiation domination (high R, low T) to temperature domination (low R, high T). The MAC-line approach also suggests an avenue for gaining more confidence in extrapolations of accelerated MAC-line data to ambient aging conditions by using ultrasensitive oxygen consumption (UOC) measurements taken along the MAC line both under the accelerated conditions and at ambient. From UOC data generated under combined R-T conditions, this approach is tested and quantitatively confirmed for one of the materials. In analogy to the wear-out approach developed previously for thermo-oxidative aging, the MAC-line concept can also be used to predict the remaining lifetimes of samples extracted periodically from ambient environments.},
doi = {10.5254/rct.18.81679},
journal = {Rubber Chemistry and Technology},
issn = {0035-9475},
number = 1,
volume = 91,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

FIG. 1. FIG. 1.: Arrhenius plot of induction times and oxygen consumption shift factors for an EPDM o-ring material.

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