Thermal ageing and lifetime prediction for organic matrix composites

During their thermal ageing in air, organic matrix composites undergo a superficial oxidation leading to a 'spontaneous' cracking. The aim of this article is to present a new strategy of investigation intended to minimise empirism in the field of lifetime prediction. It is based on a kinetic model starting from a radical chain mechanism, initiated by hydroperoxide decomposition, and coupling the oxygen diffusion and consumption kinetics. The model gives access to the thickness distributions of all the chemical changes happening during the exposure. All its parameters have a physical sense and are checkable experimentally In addition, they obey Arrhenius law, which is not the case for the usual global properties. Some significant results showing the model efficiency are reported. Then, it is shown how, in the near future, the model will be usable to predict changes in mechanical properties.