2. The organic chemist's and polymerist's point of view

The "target" of chemical aging is always a small group of atoms, for example an ester group in a hydrolysis process, or a methylene group in an oxidation process. From the point of view of organic chemistry, it's the transformation of these groups that needs to be studied. For example, hydrolysis of the ester group leads to acid and alcohol groups:

The accumulation of acids and alcohols is likely to modify certain properties of use, as we shall see in paragraph 4. However, hydrolysis can be accompanied by modifications on another structural scale, and these...