Time Dependent Response of Polymers: PEEK Performance

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Time Dependent Response of Polymers PEEK
Performance

• By Andrew Darmawan

Supervisors
Dr. Rebecca Powles
Prof. David Mckenzie
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Elastic Materials
Crystalline atomic structure
Strong Inter-atomic Forces
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Viscoelastic materials are those for which the
relationship between stress and strain depends on
time. E.g. Polymers.
Illustration by David Zinn
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Pitch drop experiment

• Started in 1927 by University of Queensland
  Professor Thomas Parnell.
• A drop of pitch falls every 9 years

Pitch drop experiment apparatus
Pitch can be shattered by a hammer
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VentrAssist LVAS

• Left Ventricular Assist System (LVAS)
• Used as alternative to heart transplant or a
  bridge to recovery
• Only one moving part

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Evolution of the heart pump
Polymers

• Why Polymers?
• Easier manufacture (injection molding)
• Cheaper
• Density is a better match with the human body

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PEEK (Poly ether ether ketone)
Properties

• Why PEEK?
• Biocompatible
• Strong
• Smooth

Chain Structure
ketone
ether
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Experiment 1 Newtons Rings

• Light is reflected from both sides of a thin film
• Interference occurs
• The interference pattern represents a contour map
  of the surface.

Optical flat
Reflective polymer
Air film (made by indentation)
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Experiment 1 Newtons Rings
Camera
Beam splitter
Apparatus
Sample with optical flat
Laser
Paper
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10min
60min
Results
480min
4300min
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Experiment 2 Surface Profiler
Pin dragged across surface Produces a profile of
the indentation.
Tencor Alpha-step
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Conclusions Surface profiling is a useful method
for measuring the time dependant response of
polymers. PEEK has a time dependant response to
indentation (appears to be exponential) (the
sample recovered by approximately 8 in 87
minutes)
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Other applications
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Summary
3. Ventracors VentrAssist
4. PEEK
5. Experiment 1 Newtons Rings
6. Experiment 2 Surface Profiler
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