The structures of new forms of polytetrafluoroethylene obtained by modification of commercial PTFE using different methods

The structures of different polytetrafluoroethylene (PTFE) powder forms—PTFE-FORUMTMobtained by thermal treatment, PTFE-TOMFLONTM obtained by irradiation and crushing in vortex mill and PTFE-F4—were investigated by means of IR, ESR, NMR and X-ray spectroscopy methods. Ab initio calculations were used for interpretation of the experimental data. All the studied PTFE forms are in general crystals with amorphous regions in their structures. The nature of amorphism in FORUMTM differs from those in PTFE-F4 and TOMFLONTM. The molecular structure of PTFE remained mostly intact in all modified forms. FORUMTM is a low-molecular form of PTFE built from helixes with terminal –CFCF2CFCF2 and branching–CF3CF3 groups. The terminal –COF groups emerge in the chains in the PTFE-F4 and FORUMTM structures after irradiation in air. Unlike TOMFLONTM, in which structure radicals were detected, their presence in the structures of PTFE-F4 and FORUMTM was observed only after irradiation.