4. Representative materials and specimens. Exposure conditions

To study the aging behavior of materials, we need specimens that are representative of the CMO to be characterized (in terms of material, processing, etc.), as well as reliable, properly regulated and robust means of exposure. The cost of testing is a compromise between the choice of aging parameters likely to influence the behavior of the CMO, the number of specimens to be tested, the complexity of the specimens to be manufactured, and the duration of the exposures required to produce valid predictive models. This requires an experimental design to optimize the number of tests according to the parameters to be evaluated.

The choice of tests is also very important, as a test should only be carried out if it is not covered by a similar, more stringent test. Similarly, the choice of a combined test, more difficult to implement but more representative of the real environment,...