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