Study on structural evolution of polytetrafluoroethylene irradiated by electron beam under stretching using SAXS/WAXS

• Structural evolution of PTFE and crosslinked PTFE with different radiation doses during stretching were studied by SAXS/WAXS.
• The evolution behavior provided a reasonable explanation for mechanical property.
• The experimental results verified that the lamellae can be protected from damage in only high concentration network structure.

The structural evolution of polytetrafluoroethylene (PTFE) and crosslinked PTFE (XPTFE) irradiated by electron beam was studied using synchrotron wide- and small-angle X-ray scattering (WAXS/SAXS) before and after stretching. Before stretching, the crystal size, crystallinity and long period of lamellar decreased with increasing irradiation dose. After stretching, crystals had a preferred orientation along stretching direction for PTFE and crosslinked PTFE. For PTFE, at breaking point, the microvoids formed and caused the decreasing crystallinity; the lamellae were arranged periodically along stretching direction. For XPTFE with low irradiation dose, the lamellar structure was destroyed at break. However, the lamellae were observed to align more orderly in XPTFE with high irradiation dose. High irradiation dose induced the high density of crosslinking molecules and network structure which has protected the lamellar under force load. The structure evolution provided a reasonable explanation for mechanical property.

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