Morphology of polytetrafluoroethylene before and after irradiation

► Fibrillar structure of as-polymerized PTFE is preserved after its sintering. ► In the sintered polymer some segments of fibrils form lamels. ► Irradiation above the melting point rearrange PTFE structure. ► New formed spherulites consist of radially extending fibrils. ► Formation of spherulites is ascribed to radiation-induced chain scission.