Photo-oxidation of acrylic-urethane thermoset networks. Relating materials properties to changes of chemical structure

Acrylic-urethane thermoset photo-ageing was investigated by various techniques including IR spectroscopy, dynamic-mechanical thermal analysis (DMTA), and micro-hardness testing. These results were used to identify the sites at which the chain oxidation reaction is initiated and the main pathways through which the degradation reaction proceeds. The chemical modifications induced by photo-ageing were qualitatively and quantitatively correlated with the modifications observed in the architecture and mechanical properties of the thermoset network. The results of this work also allow for the development of a quantitative kinetic model based on the identified mechanisms and a multi-scale approach from the molecular to the macroscopic level, which highlights the effect of the changes of the chemical structure on the modification of the macromolecule arrangement and thus on the mechanical properties. Finally, the impact of stabilisers on material ageing was studied.