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 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. Comparison with 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 best agreement is achieved with a thermal aging activation energy of 0.67 eV.