On Thermal Acceleration of Medical Device Polymer Aging

An empirical rule, the 10 °C rule, states that chemical reaction rates are doubled for every 10 °C temperature increase. This is often used in thermally accelerated medical device polymer aging studies. Here, theoretical evidence and limitations for the rule are analyzed. Thus, a new and more accurate rule based on averaging Arrhenius chemical reaction rate ratios over typical activation energies 0.1 eV-0.9 eV in the normal medical device accelerated test temperature interval 25 °C-70 °C is proposed. A comparison of the 10 °C rule shows that the 10 °C rule provides similar estimates, but only at the reference temperature 25 °C. Fitting the reaction rate ratio based on the Arrhenius equation using the reference temperature 25 °C to the 10 °C rule data reveals that the best agreement is achieved with thermal aging activation energy of 0.67 eV.