Polymers Behaviour under Ionizing Radiations: In-Situ Characterization of Macromolecular Defects and Outgassing

Polymers are made of long chains of repeating units linked <i>via</i> covalent bonds. Those chains are organized in function of the chemical structure of their repeating units; leading to different levels of organization. Due to these organization levels, polymers have different transition and relaxation temperatures and are more often than not semi-cristalline. Crystallites are embedded in amorphous phases and radicals created under ionizing radiations, that are the reactive species in polymers, can be trapped therein and react long after irradiation either with the oxygen or with humidity from the air.<br/>Polymer are subjected to gas permeation and diffusion. Therefore, any analysis performed off-line, after irradiation is susceptible to represent not the state of the sample freshly irradiated but its state after subsequent post-irradiation evolution.<br/>In order to make sure to actually study the effect of radiations, we have, at CIMAP, developed set-ups enabling to studying polymers under various temperatures and atmospheres and under different ionizing radiations be them ion or electron beams. Polymers are submitted to radiolysis and studying radiation-induced gas-emission is of great interest in assessing their ageing mechanisms, as gaseous products are the parallel of defects created in the polymer chains.<br/>I will present not only experimental set-ups for online study of polymers but also beams available at GANIL for these studies and some results on polymers of interest.