Structural changes of polytetrafluoroethylene during irradiation in oxygen

• The structural change of PTFE irradiated in O2 is different from that in vacuum.
• The double bond is not found in PTFE after irradiation in oxygen.
• The new groups like COF, COOH and CF3 are formed in PTFE after irradiation.
• The expansion of crystallite size is observed in the irradiated PTFE.

To study the effect of irradiation on PTFE structure and prepare modified PTFE micropowder, PTFE was irradiated with dose up to 4 MGy in oxygen at room temperature. The structures of both irradiated and unirradiated PTFE samples were comparatively characterized by IR, XPS, Raman spectra and XRD measurement. The results showed that new groups of acyl fluoride (COF), carboxylic acid (COOH) and trifluoromethyl (CF3) were formed under heavy radiation exposure in oxygen. In addition, the expansion of crystallite size or crystal lattice was first reported for the irradiated PTFE. The formation of new chemical groups and the expansion of crystallite size were elucidated by structural changes occurring in irradiation.