Interaction between radio-oxidized polypropylene and gaseous HCl. Part 1. Qualitative evidence

•Polypropylene is reacted with HCl to mimic cross-infection of radio-oxidized polymers.•Evolution of radio-oxidized PP which has reacted with HCl is evaluated at the molecular scale.•Qualitative evaluation of possible interactive pathways is offered. Polymers are widely used in various sectors of the nuclear industry where they can become contaminated with fission and activation products. The resulting nuclear wastes consist in a mixture of different polymers, which may be classified as long-lived intermediate-level waste (LL-ILW) if they have been in contact with long-lived radionuclides. From their production, polymers will be radio-oxidized. If different type of polymeric materials degrade close to each other, cross-infection can happen and alter the known degradation mechanisms. The objective of this work is to investigate the interaction between the HCl, which mimic polyvinyl chloride (PVC) degradation, and radio-oxidized polypropylene (PP). Polymers are characterized before interaction with HCl: additives are identified in the pristine polypropylene and evolution of the films with dose are evidenced (POH, POOH and CO bonds are increasing with dose). Evolution under HCl exposure of PP and of radio-oxidized PP is followed by different techniques, in situ and ex situ. Upon contact, a rapid evolution of the gases (HCl consumption in addition to CO2, H2O and CO formation) in the reactor is observed for the 15 first hours, followed by a slow evolution. At the molecular level in the polymer, in situ FTIR spectroscopy analyses show a decrease of the POH/POOH broad infrared peak along with the formation of ketone bonds. CCl bonds are also evidenced. Finally, sorption of HCl is shown. Hypotheses on preferred mechanisms are suggested, some of them being evaluated in Part 2 of this article.