Ultrasonic evaluation of polyether ether ketone and carbon fiber-reinforced PEEK

Polyether ether ketone (PEEK) and carbon fiber-reinforced (CFR) PEEK are commonly used in medical implants. This study evaluated the mechanical moduli of PEEK and CFR PEEK using nondestructive, ultrasonic tests. The Young’s modulus of CFR PEEK was determined in all the spatial directions. Ultrasonic attenuation has not been studied extensively in PEEK, and not at all in CFR PEEK. The broadband ultrasound attenuations (BUAs) were determined for PEEK and CFR PEEK. The average Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio of PEEK were 4.21, 1.52, 6.25, and 0.388 GPa, respectively. The maximum and minimum Young’s moduli of CFR PEEK were 15.1 and 5.1 GPa measured parallel and perpendicular to the fiber axis respectively. The longitudinal and transverse BUAs of PEEK were 1.33 and 4.37 dB/cm MHz, respectively. The longitudinal BUAs of CFR PEEK parallel and perpendicular to the fiber axis were 2.43 and 1.45 dB/cm MHz, respectively. Characterization of Young’s modulus of CFR PEEK in all the spatial directions is useful for stiffness matching in implant design. The BUA values are useful in modeling the interaction of ultrasound and the PEEK materials and can also be used for developing non-destructive tests to find structural defects in implants made from these materials.