The effect of crystallinity on the fracture of polytetrafluoroethylene (PTFE)

The extremely low coefficient of friction and biocompatibility provided by the inert nature of polytetrafluoroethylene (PTFE) have lead to its application in a wide range of biological implants ranging from single component PTFE structures to sliding contact pads in complex joints. In vivo fracture has been identified as a major cause of failure in these implants. It has recently been shown that the fracture behavior of PTFE undergoes transitions from brittle-fracture below 19 °C to ductile-fracture with fibril formation and large-scale plasticity over 30 °C associated with crystalline phase transformations. In this paper the formation of fibrils and an associated increase in JIC fracture toughness are revealed to be restricted by an increase in crystalline content in PTFE. [LAUR 05-2223]