| Popis: |
In many cases of accelerated thermal aging of polymeric materials of electrical interest, for various Arrhenius lifelines corresponding to various properties of a given material, to various materials with the same endlife criterion, and to various endlife criteria for a given material, a linear correlation exists between the logarithm of the preexponential factor and the activation energy. An attempt is made to demonstrate that, in many important cases, the existence of such a correlation, called the compensation effect, results from the non-Arrhenian character of the kinetics. An experimental and a numerical example show that, for an aging process resulting from two successive steps, the non-Arrhenian kinetics leads to an apparent compensation effect. Another experimental and numerical example shows that, for a sequential process, an apparent compensation effect can also be observed in a comparative study of various materials of close composition. > |
