nanocellulose reinforced pvdf speaker

COLLEGE OF ENGINEERING
Chemical, Biological & Environmental Engineering
NANOCELLULOSE REINFORCED PVDF SPEAKER
Background
Hussain Al Zayer, Alex Van, Greg Wu
Sponsored by Dr. John Simonsen
• Piezoelectric materials ​generate mechanical
strain proportional to applied electric charge​
• PVDF is a piezoelectric polymer when it is in
the β-phase​ (See Figure 2)
• PVDF film exhibits piezoelectric behavior in
specific planes relative to an applied electric
field (See Figure 1)
• Crystalline nanocellulose (CNC) filler
provides electrical and mechanical properties
and potential cost savings
• Piezoelectric PVDF films can serve as an
audio speaker
Objective
Investigate the use of crystalline nanocellulose (CNC) as a filler in polyvinylidene fluoride (PVDF)
films for use in two-dimensional audio speakers.
Tests were performed to investigate the effect of:
• Filler content (% CNC)
• Thickness of films (µm)
The effect of these parameters were analyzed by looking at
• Volume and sound quality of speaker
• Frequency range of produced sound
Results
Future Work
• Construct high voltage operational amplifier
• Try new frame designs (ring-shaped, different
sizes)
• Poling the PVDF films by subjecting to large
electric field
• Perform tests to determine mechanical
robustness
• Cast with other methods to get wrinkle free
PVDF films, to improve speaker sound
quality
• Explore relationship between direction
manufacturing geometry and volume
produced
• Compare thickness and sound results at same
content filler of nanocellulose
Comparison of frequency vs. audio volume for different filler contents of nanocellulose in PVDF
films and film coatings are summarized in the plots below.
https://www.americanpiezo.com/knowledge-center/piezo-theory/piezoelectric-constants.html
http://pubs.rsc.org/en/content/articlehtml/2013/ra/c3ra45134h
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Methods
• PVDF film is cast in a solution
of nanocellulose and DMAC for four hours​
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Acknowledgment
Frequency (Hz)
Figure 4: Original frame design made use of four c-clamps
to secure film and did not include a transformer or coaxial
cable. For testing a small weight was placed on the film to
help produce noise.
Figure 5: Volume between frequencies 800-16,000 Hz for a
0% CNC film that was 30 μm thick. The film has been
metalized with silver ink. Large peaks below 1000 Hz is due to
background noise.
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Volume (dB)
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Figure 6: Volume produced between frequencies 80016,000 Hz for a 16% CNC film that was 37 µm thick
film, The film has been metalized with silver ink. The
CNC filled film has more peaks that pass -66 dB than the
0% film.
• Meisam Shir Mohammadi – PhD Student
• Andy Brickman – Electrical Assistance
• Milo Clauson – Frame Design
• Dr. Phil Harding – General Guidance
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• Dr. John Simonsen – Project Sponsor
• Scott Hong Cheng Tan – Frame
reconstruction
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Frequency (Hz)
Figure 3: CNC and DMAC solution is applied in rotary
caster with a heat gun to maintain 60 oC for four hours
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Volume (dB)
• Frequency of applied field is adjusted with
waveform generator to determine
minimum frequency
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• Thickness is then measured with a
micrometer​
• Film is coated with silver ink on both sides to
create conductive film
• PVDF films filled with nanocellulose has
better sound quality compared to non-filled
films
• Sputter coated PVDF films produce higher
volume compared to films coated with silver
ink
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Volume (dB)
Figure 1: Different strains
that a piezoelectric film can
experience for an electric
field in a given direction
Conclusion
Figure 2(a): α-phase of PVDF
Figure 2 (b): β-phase of
PVDF where the fluorine
atoms are aligned on one side
and hydrogen on the other.
Frequency (Hz)
Figure 7: Volume by a 16% CNC that was 37 µm thick
film. The film has been metalized by sputter coating
with gold. Large peaks below 1000 Hz is due to both
background noise and noise produced by the film.