1. A NOVEL METHOD TO IMPROVE DIELECTRIC PROPERTIES IN CONDUCTIVE FILLER / POLYMER COMPOSITES
M. Arjmand, U. Sundararaj
Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Canada
PPS – 28
Dec 11-15, thailand

2. Embedded Capacitor
In a typical microelectronic product, around 80% of the electronic components are passive components, such as capacitors, which take up more than 40% of the printed circuit board (PCB) surface area.1 2
1J. X. Lu, K. S. Moon, J. W. Xu, and C. P. Wong, J. Mater. Chem. 16 (16), 1543 (2006).
2www.murata.com

3. Chronological Development of Capacitors
Conventional Capacitors like Ceramic Capacitors
High-k Ceramic Powder / Polymer Capacitors
Conductive Filler / Polymer Capacitors (CPCs)

4. What Makes CPCs Different For Use As Charge Storage Material? (Cont’d)
The electric dipole has a magnitude equals to the strength of each charge times the separation between charges.
Interfacial Polarization + + + + - + + + + +
Electronic Polarization

5. Challenges in Manipulating CPCs as Charge Storage Materials
High real permittivity is achievable close to or above percolation threshold.1
The insulator–conductor transition, which occurs at percolation threshold, precludes CPCs from being used above the percolation threshold.
There is a typically narrow insulator-conductor transition window to regulate dielectric properties.
1Dang ZM, Yao SH, Yuan JK, and Bai JB. J Phys Chem C 2010; 114:

6. Strategies to Avoid Sharp Insulator – Conductor Transition
Covering the Surface of Conductive Filler with an Insulative Layer
Introducing Secondary Particle as Insulating Barrier

7. Conductive Filler Alignment: A Novel Approach to Improve Dielectric Properties
The Inverse Relationship Between MWCNT Alignment and Electrical Conductivity1
The Direct Relationship Between Electrical Conductivity and Imaginary Permittivity
Compression Molding
Injection Molding
Arjmand M, Mahmoodi M, Gelves GA, Park S, and Sundararaj U. Carbon 2011; 49:

8. Experimental (Cont’d)
Injection Molding
BOY 12A
Polystyrene Masterbatch 20 wt%
(MB )
Blending with Twin-Screw Extruder
“Coperion ZSK”
Compression Molding
Pure Polystyrene
(Styron® 610)

9. Processing Parameters
Experimental
Composite Molding
Compression Molding: Carver Plate Press: 210 oC, 38 MPa, 10 min
Injection Molding
Processing Parameters
240
Injection Velocity
(mm.s-1)
215
Melt Temperature
(°C)
100
Injection Pressure
(bar) 60
Mold Temperature

10. Morphological Analysis
Injection Molding
Compression Molding

11. Effect of Alignment on Insulator – Conductor Transition Window
0.7 – 2.0 wt%
5.0 – 8.5 wt%

12. Conceptualization of the Effects of Alignment on Real and Imaginary Permittivities+ + - + + + + - + +

13. Effects of Alignment on Imaginary Permittivity

14. Effects of Alignment on Real Permittivity

15. Effects of Alignment on Dissipation Factor

16. Conclusions
MWCNT alignment widened the typically narrow concentration window near the percolation threshold.
The results showed that the MWCNT alignment reduces the dissipation factor in conductive filler / polymer composites.
Due to industrial applications of injection molding process, the positive impact of MWCNT alignment on the dielectric properties is of high significance.

17. Acknowledgements
Natural Sciences and Engineering Research Council of Canada (NSERC).
Mr. Mahmoodi and Dr. Park, University of Calgary for assistance with the mold design and manufacturing.
Mr. Apperley and Dr. Okoniewski, University of Calgary for assistance with electrical properties measurements.
Americas Styrenics LLC, for providing pure polystyrene.

18. Any Questions!?

19. Injection Molding vs Compression Molding: Length Distribution

20. Raman spectroscopy ratios parallel/perpendicular
Two significant characteristics in the Raman spectra of the MWCNT/polymer composites are the D band (disorder band), and the G band (graphite band).
The Dװ/D ┴and Gװ/G ┴ parallel/perpendicular to the flow direction were used to determine the degree of MWCNT alignment.
Raman spectroscopy ratios parallel/perpendicular
┴/DװD
┴/GװG
Compression Molding
1.01
Injection Molding
1.66
1.51

21. Raman Spectroscopy

22. Rogers Corporation Product X-band Dielectric Properties
Dielectric Constant
Dissipation Factor
Volume Resistivity
(Ohm cm)
R0 3003TM
PTFE CERAMIC
3.00
0.0013
1018
R0 3203TM
3.02
0.0016
1013
R04003CTM
HYDROCARBON CERAMIC
3.38
0.0029
1015

23. Processing Parameters
Experimental
Injection Molding
Our previous study showed that the melt temperature had the greatest impact on MWCNT alignment followed by the injection velocity, while the impacts of mold temperature and injection/holding pressure were insignificant.1
Processing Parameters
240
Injection Velocity
(mm.s-1)
215
Melt Temperature
(°C)
100
Injection Pressure
(bar) 60
Mold Temperature
Parameter
Value (mm) a
22.86 b
10.16
c, d 1 e 2 f 10
1 Mahmoodi M, Arjmand M, Sundararaj U, Park S. Carbon 2012; 50(4):