Polyether ether ketone (PEEK) is an organic polymer
thermoplastic used in engineering applications and medical implants.
Synthesis:
PEEK polymers are produced by step-growth polymerization by the
dialkylation of bisphenolate salts.
Properties:
PEEK is a colorless semicrystalline thermoplastic with excellent
mechanical and chemical resistance properties. The Young's
modulus
is 3.6 GPa and its tensile strength 90 to 100 MPa (see
below). It
is highly resistant to thermal degradation as well as attack by both
organic and aqueous environments.
Density
1320 kg/m3
Young's modulus (E)
3.6 GPa
Tensile strength (σt)
90-100 MPa
Elongation @ break
50%
Notch
test
55 kJ/m2
Glass temperature
143 °C
Melting point
~343 °C
Thermal Conductivity
0.25 W/m.K
Water absorption, 24 hours (ASTM D 570)
- 0.1%
Usage: Because
of its strength, PEEK is used to fabricate items used in demanding
applications, including bearings, piston parts, pumps, compressor plate
valves, and cable insulation. It is one of the few plastics compatible
with ultra-high vacuum applications. Thus, it is used in the aerospace,
automotive, teletronic, and chemical process industries, extensively.
PEEK is also considered an advanced biomaterial used in medical
implants.
In
the spine area, it is mainly used for production of interbody cages,
and recently, outer coverings of the rods. When used in production of
cages, its advantages include its similar Young's modulus to that of
the bone. Thus, the risk of cage subsidence is lower than that of
metallic cages. Another advantage of the PEEK cage is that it is
radiolucent. Its main disadvantage is that its hydrophobic nature.
Thus, it will never bonds to bone, unlike titanium. Therefore, to
achieve a solid fusion, one has to select afiller (inside the cage)
that has a high likelihood of fusing.
