Analysis of radiation induced degradation in FPC-461 fluoropolymers by variable temperature multinuclear NMR

Solid state nuclear magnetic resonance techniques have been used to investigate aging mechanisms in a vinyl chloride:chlorotrifluoroethylene copolymer, FPC-461, due to exposure to γ-radiation. Solid state 1H MAS NMR spectra revealed structural changes in the polymer upon irradiation under both air and nitrogen atmospheres. Considerable degradation is seen with 1H NMR in the vinyl chloride region of the polymer, particularly in the samples irradiated in air. 19F MAS NMR was used to investigate speciation in the chlorotrifluoroethylene blocks, though negligible changes were seen. 1H and 19F NMR at elevated temperature revealed increased segmental mobility and decreased structural heterogeneity within the polymer, yielding significant resolution enhancement over room temperature solid state detection. The effects of multi-site exchange are manifested in both the 1H and 19F NMR spectra as a line broadening and change in peak position as a function of temperature.