On the use of Arrhenius law in the domain of polymer ageing

Arrhenius law is generally used to represent the temperature dependence of polymer ageing kinetics. Its application to such phenomena is based on hypotheses that are recalled in a first chapter. It is then demonstrated that it is practically impossible to be checked on the basis of experimental results. The following chapters are devoted to the presentation of ageing cases where Arrhenius law is not obeyed. Trivial cases due to the presence of transitions in the temperature interval under consideration are first recalled. Then, less trivial 'non arrhenian' cases are described. The non arrhenian character can be due to the coexistence of competitive reactions with distinct activation energies or to the coexistence of kinetic regimes controlled or not by diffusion of molecular reactants such as oxygen or water, or of reactive species such as macro-radicals. It appears that the cases where ageing obeys Arrhenius law could be the exception rather than the rule. (authors)