Biomedical Engineering Reference
In-Depth Information
developed to thermally accelerate the post-
irradiation degradation mechanisms of UHMWPE
after gamma sterilization in air
[26]
. Because of
its inherent thermal resistance, conducting analo-
gous accelerated thermal aging experiments on
gamma-sterilized PEEK is unwarranted, because
previous thermal aging temperatures used for
UHMWPE (70
e
80
C) are far below the glass transi-
tion temperature inPEEK(144
C). In summary, below
the glass transition, and for doses below 600 kGy of
gamma radiation, postirradiating aging is not expected
to be a clinically relevant concern with PEEK bioma-
terials as it has been, historically, for UHMWPE.
interface in FRP composites after exposure to
simulated physiologic saline environments,
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(2007)
209
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220.
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polyetheretherketone composite in physiolog-
ical
6.6 Summary
PEEK is a remarkably stable polymer, thanks to its
resonance-stabilized, aromatic structure. Conse-
quently, the available literature over the past two
decades demonstrates that PEEK and its composites
will exhibit long-term stability in aqueous environ-
ments at body temperature. Reported data also show
that PEEK and its composites will not be affected by
repeated exposures to steam or gamma radiation
sterilization. Furthermore, postirradiation aging is
not expected to be a concern with PEEK, as it is with
other aliphatic polymers such as polyethylene,
because of the short lifespan of macroradicals within
the material. The stability of PEEK has implications
for its biocompatibility, which is covered in the
following chapter.
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17
(8)
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781
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