In‐Situ Photorheology and Electron Spin Resonnce to Assess Polymer Photoaging

It is known that polymers ages under UV irradiation. Thus, to predict polymer photo durability it is necessary to be able to characterize their evolution at a molecular level. FTIR spectroscopy gives the chemical evolution of the material by the analysis of their photoxydation products. UV coupled Melt Rheology and ESR techniques provide the evolution of the molecular structure as a result of chain scission and crosslinking. Due to the large frequency spectrum obtained by ESR, we were able to precise the chain scission/crosslinking/recombination reactions. Moreover, the local character of the ESR technique gives additional information on the heterogeneous character of these reactions. Till to now it was not so common to use ESR experiments to assess photo‐oxidation of elastomers and even more for UV in situ irradiation. Our results proved the validity of this technique and will be the beginning of new further developments, for instance to reach to indentify the radicals species by a suitable choice of the nature and the functionality of the probe.