Material propertiesStrength of poly-ether-ether-ketone: Effects of sterilisation and thermal ageing

This paper investigates the strength of polyether-ether-ketone (PEEK) after sterilisation and thermal ageing. PEEK specimens were divided into five groups, according to whether the specimens had been annealed, sterilised or aged. Specimens were subjected to either static or dynamic three-point bend tests. Static tests involved loading the specimens until a maximum displacement of 40 mm was reached. Dynamic tests involved applying a sinusoidally varying force at a frequency of 5 Hz. The maximum force applied to a specimen was based on a percentage of the static yield strength. Testing continued until failure or run out of 10 million cycles. Sterilisation and ageing resulted in no significant change in the static yield strength. Annealing was found to significantly increase the yield strength. For the dynamic tests, the fatigue strength was in the range 99.4 to 107.4 MPa; sterilisation and thermal ageing were found to have no effect on fatigue strength.