Decomposition and CO2 evolution of an aliphatic polymer under bombardment with high energy heavy ions

Foils of the aliphatic polymer polyvinyl acetate (PVAc) were exposed to swift heavy ion beam irradiation with Xenon, Gold, and Uranium ions with kinetic energies up to 2 GeV, corresponding to transferred energies dE/dx between 8 and 18 MeV/μm, with different fluences between 1 × 109 and 1 × 1012 ions/cm2 at room temperature. The ion induced chemical changes were studied by in-situ Fourier-transform Infrared Spectroscopy and Quadrupole Mass Spectrometry. Apart from a general reduction of the IR absorption bands, showing the degradation of the polymer by side chain scission, the appearance of a new band, assigned to the CO2 group, was observed. Volatile molecular fragments of various species from H2 up to CO2 lead to a considerable mass loss of the polymer. The structural changes lead to a reduction in the thermal stability of the residual polymer. The results are technically relevant for use of the material in space applications and particle accelerators.