Multi-reaction ageing as an explanation for the ageing compensation effect

The Ageing Compensation Effect (ACE) observed in thermal ageing tests of several insulating materials may be a consequence of two or more important ageing reactions in the material and as such an apparent phenomenon. This possibility is illustrated both in general terms and by numeric examples. It is shown that always when there are two or more reactions with different activation energies (halving intervals) and at least one of the reactions has non-linear characteristics (changes in a physical property are in nonlinear relationship to changes in a relevant chemical concentration) there is a distinct possibility for ACE to appear. Using two numerical examples it is shown that ACE in fact is produced and that some published test results can be treated using two-reaction process characteristics to produce exactly the same ACE as directly derived from the observed results. Applying the same logic even one diffusion controlled ageing reaction seems to be able to produce ACE. The main practical result from this work is a warning: the intentions to use ACE as means to predict material behaviour are suspect, unless the chemical ageing process is accurately known