3,84,5
5,3
9,5
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
9,0
10,0
1500 bar packing pressure 2200 bar packing pressure
Bu
lkR
esi
sta
nce
[m
Ωcm
²]
PP-Gr-CNT PP-Gr-CB
• Parameters of 24 experimental design
• Melt temperature
• Mould temperature
• Packing pressure
• Material
Melt temperature has an significant influence on the bulk resistivity of
moulded parts � the potential of reducing the bulk resistance is about40 % using CNT-Compound and about 8 % using CB-Compound
A correlation between mould- and
melt temperature on the electrical properties is the main message of
figure 4
By increasing the mould temperature
the bulk resistivity decreases at both
materials significantly
Figure 5 shows the effect of packing pressure on the bulk resistivity. An
increase of packing pressure increases the resistivity of the moulded part
� negative effect
Packing pressure less than 1500 bar was not investigated. Maybe it is
possible to reduce the resistivity further
Conclusion:
• High temperatures of melt and mould are efficiently to increase theconductivity of injection moulded parts because of decreasing viscosity
and better network formation of conductive fillers
• High packing pressure impedes the network formation due to high
differences of pressure inside the cavity. Long time balancing
processes of pressure differences might be a problem for betterconductivity
• Carbon Nanotubes are ableto reduce the melt viscosity
in reference to Carbon Black
„Processing window of CNT-Compounds for
injection moulding“
• Mouldability diagram for
• (red) PP-Gr-CNT-Compound
• (blue) PP-Gr-CB-Compound
• Melt temperatures above 340 °C and mould
temperatures above 140 °C were not investigated
• Comparable filler contents of graphite and Carbon Nanotubes
(CNT) respectively Carbon Black (CB)
• Moulded part: Testing plate with 20 cm³ volume and part
thickness of 2 mm (demonstrator for bipolar plates)
CarboPlateJ. Dörner, J. Wortberg
Universität Duisburg-Essen
• Figure 3 shows results of an
effect study of melttemperature on the bulk
resistivity
• The left dark blue bar shows
the average bulk resistivity of
the moulded parts at 300 °Cincluding all measuring values
at 300 °C and varying otherparameters of experimental
designFigure 3: Effect of melt temperature on bulk resistance
Figure 4: Effect of mould temperature on bulk resistance
Figure 5: Influence of packing pressure on electrical resistance
Figure 1: Moldability diagram of CNT- and CB-Compounds
Figure 2: 3D model of testing plate
The target of CarboPlate is the development of larger bipolar plates
than possible by starting the project in 2009 (50 cm² active surface).With new fillers like Carbon Nanotubes and optimized injection
moulding processes it is possible to reach the goals. This poster
shows a comparison of two highly filled compounds with equal fillercontents. The only difference is the substitution of Carbon Black with
Carbon Nanotubes.
Level Material
Melt
Temperature
[°C]
Mould
Temperature
[°C]
Packing
Pressure
[bar]
1 PP-Gr-CNT 300 80 1500
2 PP-Gr-CB 320 120 2200
Table 1: Parameters and levels for experimental design
5,3
3,1
7,77,1
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
9,0
10,0
300 °C Melt Temperature 320 °C Melt Temperature
Bu
lk R
esi
sta
nce
[m
Ωcm
²]
PP-Gr-CNT PP-Gr-CB
5,6
2,7
9,0
5,9
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
9,0
10,0
80 °C Mould Temperature 120 °C Mould Temperature
Bu
lk R
esi
sta
nce
[m
Ωcm
²]
PP-Gr-CNT PP-Gr-CB
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