AN ULTRASENSITIVE TECHNIQUE FOR TESTING THE ARRHENIUS EXTRAPOLATION ASSUMPTION FOR THERMALLY AGED ELASTOMERS

We present a general approach for more confidently correlating accelerated aging results with aging under service conditions using the Arrhenius methodology. We first show that, as a result of complex diffusion-limited oxidation effects, time/temperature correlations may occur for some properties but not for others. To rigorously extrapolate high temperature results to low temperatures, we sought an ultrasensitive technique correlated to macroscopic degradation and capable of measurements at or near service temperatures. We achieved this objective by monitoring oxygen consumption rates at high (accelerated) temperatures, to establish the necessary correlation, and at low temperatures (down to 23 degrees C), to determine their temperature-dependence in the extrapolation region. Because easily measurable oxygen consumption rates of 10(-13) mol/g s correspond to decades of predicted lifetime for most elastomers, this approach increases confidence in long-term predictions and therefore provides a means of testing Arrhenius extrapolations.