Rule of Thumb for Product Life Estimation: The 10-Degree Rule

 

In this blog post, we discuss the 10-degree rule as a quick estimation for product life time.

Polymer materials are more and more used as protection and as barriers towards harsh and aggressive chemicals. As already previously discussed, plastic part failure is linked to phenomenological and human causes such as material misselection and poor specification. To prevent part failure, an increased focus on material selection is beneficial. In material selection, especially in the practical validation tests, estimation of part lifetime is needed. If the part specification states that the part lifetime needs to be 3,000 hours, the selected polymer needs to be checked for suitability.

Here comes the 10-degree rule into the game. The 10-degree rule, also called the Q₁₀ rule, the RGT-rule (ReaktionsGeschwindigkeit-Temperatur-rule), or Van’t Hoff’s rule, states that the polymer thermal aging rate k is doubled for every temperature delta of 10°C. It is based on the Arrhenius relationship, which shows the temperature dependence of reaction rates.

The 10-degree rule, also called the Q₁₀ rule.

Also, more common written as:

Accelerating part testing by increasing temperature

In essence, the 10-degree rule says that for every 10°C increase, the reaction rates double. As a consequence, the useful life time of the material will be halved. Since it is an exponential function, test temperature changes of for example 50°C will result in reaction time changes by factor 32.

In practical terms, it means instead of testing at room temperature (25°C), increasing the test temperature in 10°C steps will accelerate testing enormously. Furthermore, extrapolation to longer times is possible.

One last remark: the 10-degree rule is a purely phenomenological rule and the predictive character is limited.

Thanks for reading and #findoutaboutplastics

Greetings,

Herwig Juster

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Literature:

[1] https://www.mddionline.com/design-engineering/general-aging-theory-and-simplified-protocol-accelerated-aging-medical-devices

[2] https://www.ptonline.com/articles/materials-the-mystery-of-physical-aging-part-3