Biomedical Engineering Reference
In-Depth Information
interface
. The overall mechanical behavior of
a composite is thus governed by the properties of
the individual constituents and the interfaces
between them. In the case of PEEK, the polymer is
typically designed as the matrix of the composite
and constitutes most of the volume in the polymer
composite.
As already alluded to previously in this chapter,
carbon and glass fillers were among the first rein-
forcement additives for PEEK to increase its strength
and stiffness
[29]
. PEEK forms a strong interface
with carbon fibers, effectively transferring stress
between the fibers and the polymer matrix (
Fig. 1.8
).
The strength and modulus of carbon fiber-reinforced
PEEK (CFR-PEEK) depend on the size, length, and
orientation of the fibers. CFR-PEEK biomaterials are
currently used in implants for spine fusion and joint
replacement.
PEEK biomaterials are also engineered for the
biomedical, as well as their biomechanical, func-
tion. PEEK may be mixed with radiopacifiers, such
as barium sulfate, to improve visualization and
contrast in medical imaging. Image contrast grades
of PEEK are commercially available for implant
applications and are currently used in spinal
implants.
Researchers are also investigating the combination
of PEEK and bioactive fillers, such as hydroxyapa-
tite, to enhance bone growth around implants.
Although structural and image contrast formulations
of PEEK are relatively well understood, bioactive
PEEK composites represent a novel field in bioma-
terials under active research and development. In
Chapter 3 of this
Handbook
, we explore PEEK
composites more thoroughly.
1.7 Overview of This Handbook
The primary goal of this
Handbook
is to provide
a comprehensive, state-of-the-art assessment of
PEEK and PEEK composites as a family of bioma-
terials. In recent years, advances in the processing
and biomaterials applications of PEEK have been
progressing steadily. Previously, much of the
research on PEEK implants has been fragmented in
the materials science, composites, biomaterials, and
application-specific literature. Consequently, we
have also sought to synthesize data from the mate-
rials science, polymers engineering, biomaterials,
and clinical literature to make this information more
readily available and to hopefully facilitate new
research in this field.
This
Handbook
is organized in three main
sections. The first part of this
Handbook
provides the
reader with a foundation in PEEK structure, proper-
ties, and behavior. As background for this mono-
graph, we have provided in this introductory chapter
an initial summary of polyaromatic ketones as the
basis for understanding the chemical, physical, and
mechanical properties of this family of polymeric
biomaterials. Chapter 2 summarizes the techniques
for processing PEEK and fabricating PEEK compo-
nents, and Chapter 3 further covers the field of PEEK
composites. Chapters 4
e
6 describe the structure and
morphology,
fatigue and fracture behavior, and
chemical
and
radiation
stability
of
PEEK
biomaterials.
The second part of this
Handbook
summarizes the
biocompatibility of PEEK and recent developments
in the engineering of PEEK biocomposites. Chapter 7
provides an overview of studies in the literature
analyzing the biocompatibility of PEEK. In Chapter
8, the interaction between PEEK and microbiological
organisms is summarized. Surface modification of
PEEK can be achieved using bioactive coatings
(Chapter 9) or by plasma treatment (Chapter 10).
Chapter 11 covers advances in the field of hydroxy-
apatite-PEEK biocomposites, and in Chapter 12, we
describe efforts to introduce porosity into PEEK
biomaterials for creating tissue scaffolds.
The third part of this
Handbook
provides an
overview of current applications of PEEK implants.
We provide an overview of the clinical applications
Figure 1.8
Freeze fracture surface of CFR-PEEK
(PEEK OPTIMA LT130). Image courtesy of Ryan Baxter,
Ph.D., Drexel University.
