Effect of MeV protons on the phase behaviour and thermal stability of polytetrafluoroethylene

Thermomechanical spectroscopy analysis was used to study the influence of accelerated protons on the molecular-topological properties of polytetrafluoroethylene (PTFE). The study showed changes in a wide number of polymer parameters as a result of bombardment with 1, 2 and 4 MeV protons at fluences up to 2 × 10¹⁵ protons/cm². The basic topological process occurring under proton bombardment is amorphicity, as found for γ-irradiation of PTFE. The flow temperature of bombarded PTFE significantly decreases with increasing the fluxes and energy of the accelerated protons. The general process resulting from proton bombardment is cleavage of C-F bonds, leading to formation of “centered” radicals ～CF₂CF · CF₂～ and HF. The thermal stability of bombarded PTFE is below than that of virgin polymer. The rate of thermal destruction noticeably increases and the temperature of the initiation of effective thermal decomposition decreases after bombardment. The gaseous products generated during thermal destruction of the bombarded and virgin PTFE are similar.