The Taylor Impact Response of PTFE (Teflon)

Whilst Polytetrafluoroethylene (PTFE) is an unusually ductile polymer, it undergoes an abrupt ductile‐brittle transition at modest impact velocities. No previous explanation for this behaviour seems to have been presented. In this paper we examine the role of a pressure‐induced phase transition in PTFE in the failure of Taylor cylinder samples. Whilst a phase transition occurs at approximately 0.65 GPa at 21°C, the transition pressure is inversely related to temperature. Varying the temperature of the fired Taylor cylinders shows that the phase transition is likely to be involved because the critical velocity increased for decreasing temperature, despite the material fracture toughness decreasing.