Model for the Oxidative Ageing process of Elastomers

Abstract

Oxidative ageing is one of the important factors limiting the lifetime of elastomer products. The chemical reactions taking place during ageing are very complex as a result of interactions between numerous components of the compound and the reactive intermediates. The chemiluminescence method delivers a good insight into the progress of oxidative ageing reactions. This method detects the light which is emitted during the degradation of hydroperoxides that are formed during the ageing process. Using a mathematical model for the oxidative ageing process it is possible to reproduce the intensity of the chemiluminescence signal as a function of time. By fitting the calculated and the measured curves, the reaction constants used within the model can be determined. The model can be tested and a more exact determination of the reaction constants can be achieved by preparing specific compounds with different amounts of antioxidants, for instance, or by directed variation of the oxygen concentration during the chemiluminescence measurement. This approach delivers a deeper understanding of the oxidative ageing process. Using this model it is possible, for instance, to predict the impact of recipe variations. In this way, elastomer compounds can be optimised still more effectively. In addition, for example, the influence of the oxygen concentration specific to the application can be taken into account when estimating the lifetime of elastomer products.