Thickness =

From Pco and T we can draw graphs to discuss the properties of copolymer

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D= Thermal diffusivity constant

For PVDF Film                                                 D
= 6.2 x 10?? m²/s

5. Results and Discussion:

5.1 Thickness vs Pyroelectric coefficient of bilayer 21µm thick PVDF
film

Figure 7: Spatial distribution of the
apparent pyroelectric coefficient of a 21µm thick PVDF bilayer film front
side

In the above
figure,   X axis = Thickness (m)

Y axis = Pyroelectric
coefficient (a.u.)

We can observe a break
in the curve this is because of sign changes. The polarization reaches maximum
at 5µm.compared to single layer PVDF film polarization decreases if the thermal
wave moves deep inside the sample

 

 

 

 

 

 

5.2
Thickness vs Pyroelectric coefficient of three layer 30µm thick PVDF film

Figure 8: Spatial distribution of the
apparent pyroelectric coefficient of a 30µm thick PVDF multilayer film
front and back side

 

 

In the above
figure,   X axis = Thickness (m)

Y axis = Pyroelectric
coefficient (a.u.)

0-10µm polarization direction is upwards ? and polarization reaches
maximum value at 5 µm and decreases and from 10-20µm polarization direction is
downwards ? and polarization increases and from 20-30µm polarization direction
is upwards ? and there is not much change in polarization. So I would say we
can measure better polarization until 20 µm. blue curve indicate front side of
the film and the green curve indicate back side of the film.

Figure 9 Combination of measurements from 2
sides from figure 8

 

1.3   Thickness vs Pyroelectric coefficient of
bilayer 23um thick P(VDF-TrFE)70/30 mol%, P(VDF-TrFE)50/50 mol%film

 

In the below
figure,   X axis = Thickness (m)

Y axis = Pyroelectric
coefficient (a.u.)

blue curve indicates front side of the film and the green curve
indicates back side of the film.

Both sides of the film
polarized in the same direction by applying a voltage. Blue curve reaches
maximum polarization faster than the green curve. This is because of their
different mol%.  We can observe curve
changes until 23um after that polarization coefficient shows a constant value.
I would say green curve has maximum polarization so I expect it would be 70/30
mol% and the blue curve has less polarization compared to green so I expect blue
curve is 50/50 mol%.

Figure 10: Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer film
front 70/30 mol% front and 50/50 mol% back side

 

Figure 11 Combination of measurements from 2
sides from figure 10

Started measuring
polarization at different temperatures from 40°C to 120°C to determine the
polarization changes of the film caused because of temperature deference.

Figure 12: Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer       film   front 70/30 mol% and 50/50 mol% back
side

Sample heated for 10
minutes at 40°C and measured pyroeletricity at room temperature

In the above
figure    X axis = Thickness (m)

Y axis = Pyroelectric
coefficient (a.u.)

Blue curve reaches maximum polarization so I expect it would be 70/30
mol% and the green curve has less polarization compared to green so I expect
green curve is 50/50 mol%. Compared to Figure 12 there are no much changes
expect less decrease of maximum polarization

Figure 13 Combination of measurements from 2
sides from figure 12

 

Figure 14 Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer       film  
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample heated for 10 minutes at 45°C and measured pyroeletricity at room
temperature. In the above figure full of noise due to missing connections
happened during measurement.

Figure
12: Spatial distribution of the apparent pyroelectric coefficient of a
23um thick P(VDF-TrFE) bilayer film front 70/30 mol% and 50/50 mol% back
side

Figure 15 Spatial distribution of the apparent
pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer film front
70/30 mol% and 50/50 mol% back side

            X
axis = Thickness (m)

Y axis = Pyroelectric coefficient (a.u.)

Sample heated for 10 minutes at 50°C and measured pyroeletricity at room
temperature. Missing connections continued from figure 14. There is no change
in the graph noise continues.

Figure 16 Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis = Thickness (m)

Y axis = Pyroelectric
coefficient (a.u.)

Sample heated for 10
minutes at 55°C and measured pyroeletricity at room temperature

Figure 17 Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer film front
70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample heated for 10 minutes at 65°C and measured pyroeletricity at room
temperature

 

 

Figure 18 Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample heated for 10 minutes at 75°C and measured pyroeletricity at room
temperature

 

Figure 19 Spatial distribution of the
apparent pyroelectric coefficient of a 23um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample heated for 10 minutes at 85°C and measured pyroeletricity at room
temperature

 

 

5.4 Thickness vs Pyroelectric coefficient
of bilayer 25um thick P(VDF-TrFE)70/30 mol%, P(VDF-TrFE)50/50 mol%film

Figure 20 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

In the above
figure,   X axis = Thickness (m)

Y axis = Pyroelectric
coefficient (a.u.)

blue curve indicates front side of the film and the green curve
indicates back side of the film. Both curves show a disturbance in the starting
of the curve is because of noise. In the above figure blue curve reaches maximum
polarization so I expect it would be 70/30 mol% and the green curve has less
polarization compared to green so I expect green curve is 50/50 mol%.

 

Figure 21 combination of measuremnts from 2
sides of sample from figure 20

Figure 22 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 40°C and measured pyroeletricity at room
temperature. Compared to Figure 20 has more noise starting of the curves and
having less noise in the end but in figure 22 we can observe a change in noise
that is having less noise in the starting and more in the end of the curve.

Figure 23 combination of measuremnts from 2
sides of sample from figure 22

Figure 24 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

 

Sample is annealed at 50°C and measured pyroeletricity at room
temperature. In the above figure we can observe change in polarization compared
to figure 20 and figure 22 caused due to change in temperature.

 

Figure 25 combination of measuremnts from 2
sides of sample from figure 24

Figure 26 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 60°C and measured pyroeletricity at room
temperature

 

 

 

 

 

 

 

 

 

Figure 27 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 70°C and measured pyroeletricity at room
temperature

Compared to figure 26 and figure 27 there is no change in the
polarization. Rather we can observe change in noise

 

Figure 28 combination of measuremnts from 2
sides of sample from figure 27

 

Figure 29 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 80°C and measured pyroeletricity at room
temperature

 

Figure 30 combination of measuremnts from 2
sides of sample from figure 29

 

Figure 31 Spatial distribution of the apparent
pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film front 70/30
mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 90°C and measured pyroeletricity at room
temperature

 

Figure 32 combination of measuremnts from 2
sides of sample from figure 31

 

Even at 80°C and 90°C also we didn’t get a change in polarization I
would say this is because of measurement error

 

Figure 33 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 100°C and measured pyroeletricity at room
temperature

 

Figure 34 combination of measuremnts from 2
sides of sample from figure 33

 

Figure 35 Spatial distribution of the
apparent pyroelectric coefficient of a 25um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

Sample is annealed at 110°C and measured pyroeletricity at room
temperature.

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

 

Figure 36 combination of measuremnts from 2
sides of sample from figure 35

 

From Figure 20, 22, 24, 26, 27, 29, 31, 33 and 35 we can observe there
is no change in the graphs. Mostly it is because of sample not get polarized at
50/50 mol% side. If we measure at 120°C we may have seen a change at 70/30
mol%, because it gets depolarized at 120°C.  
 So we proceed to prepare next
film and measured with different amplification factors to know about where the
problem is occurred.

5.5 Thickness vs Pyroelectric coefficient
of bilayer 30um thick P(VDF-TrFE)70/30 mol%, P(VDF-TrFE)50/50 mol%film

 

Figure 37 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

The above figure results are not good. We thought
problem is with the amplification factor. So we measured polarization with
different amplification factors. Here it follows

Figure 38 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
soldering side at 10^6 high amplification

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

In the above figure measured polarization
of soldering side sample at high amplification factor 10^6.

Figure 39 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
front 70/30 pin side at 10^5 high amplification factor

X axis = Thickness
(m)

Y axis =
Pyroelectric coefficient (a.u.)

Measured polarization of pin side of the sample at
high amplification factor 10^5.

Compared to Figure 38 and Figure 39, I would say that
soldering side of the film at 10? high amplification factors and pin side of
the film is at 10? high amplification factors got good results compared to same
amplification factor. We can observe less noise.

Figure 40 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side at 140°C

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Sample is annealed at 140°C and measured pyroeletricity at room
temperature. We can observe full of noise due to measurement error. Next we
will measure polarization at low and high amplification factors to know about
where the problem exists.

 

Figure 41 
Spatial distribution of the apparent pyroelectric coefficient of a
30um thick P(VDF-TrFE) bilayer film front 70/30 mol% and 50/50 mol% back
side at 10^5 high amplification factor

            X axis = Thickness (m)

Y axis = Pyroelectric coefficient (a.u.)

Measured pyroelectricity of the sample at high
amplification factor 10^5.

Figure 42 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side at 10^4 high amplification factor

 X axis = Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Measured
pyroelectricity of the sample at high amplification factor 10^4. In the above
figure, we can observe full of noise.

So compared to 10?,
10?, 10? amplification factors, from figure 38, figure 41, figure 42 we can say
it’s good to measure polarization at 10? amplification factor. We will get less
noise and more clear results.

Figure 43 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side at 
high amplification factor

 X axis = Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Measured pyroelectricity  of the sample at high amplification factor.

Figure 44 Spatial distribution of the
apparent pyroelectric coefficient of a 30um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side at low amplification factor

 X axis = Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Measured pyroelectricity of the sample at Low
amplification factor 10^5.

Compared to figure 43
and figure 44, we can clearly observe at high amplification factor shows less noise
compared to low amplification factor. So I would recommend to measure at high
amplification factor based on these results. To measure high frequencies it
would be better to measure at low amplification factor. And also for low
frequencies use high amplification factor

5.6 Thickness vs Pyroelectric coefficient
of bilayer 33um thick P(VDF-TrFE)70/30 mol%, P(VDF-TrFE)50/50 mol%film

Figure 45 Spatial distribution of the
apparent pyroelectric coefficient of a 33um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Blue curve reaches
maximum polarization so I expect it would be 70/30 mol% and the green curve is
50/50mol%.both sides of the film poled in the same direction. A little bit of
noise is presented at the starting of the green curve.

Figure 46 combination of measuremnts from 2
sides of sample from figure 45

Figure 47 Spatial distribution of the apparent
pyroelectric coefficient of a 33um thick P(VDF-TrFE) bilayer film front 70/30
mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

Compared to
figure 33 in the above figure green curve 50/50 mol% lost its polarization
caused due to increase in temperature of the film. I would say green curve
reaches its curie temperature. In 70/30 mol% Blue curve less decrease of
polarization. To confirm this we polarized the film again by applying voltage
and we get results figure 49 and figure 51

Figure 48 combination of measuremnts from 2
sides of sample from figure 47

Figure 49 Spatial distribution of the
apparent pyroelectric coefficient of a 33um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

In the
above figure, we tried to polarize the film by applying voltage but we can
clearly see that green curve 50/50mol% not get polarized. To confirm this we
again increased the temperature of the film to 70°C. We can see
if any changes happened or not in figure 51.

Figure 50 combination of measuremnts from 2
sides of sample from figure 49

 

Figure 51 Spatial distribution of the
apparent pyroelectric coefficient of a 33um thick P(VDF-TrFE) bilayer film
front 70/30 mol% and 50/50 mol% back side

X axis =
Thickness (m)

Y axis =
Pyroelectric coefficient (a.u.)

There is no change in figure 51 and figure 49.
That means film not get polarized completely. So for next time we have to
increase the temperature of the film till 120°C then both the
sides of the film lose its polarization. After that we can apply voltages to
get polarize the sample then I would say the film get polarized completely and
after that without any disturbances we can measure pyroelectricity.

Figure 52 combination of measuremnts from 2
sides of sample from figure 51