1. conductive polymeric nanocomposites
Dr. Mohammad Arjmand
Polymer Processing Group (PPG)
Dept. of Chemical & Petroleum Engineering University of Calgary, Calgary, Alberta, Canada

2. calgary location

3. city of calgary Metropolitan Population: 1.2 Million
80 km East of the Front Range of Rockey Mountains
Calgary’s Economy is Tied to Oil Industry (Oilsand)

4. university of calgary Public Research University Founded in 1966
Composed of 14 Faculties and 85 Research Institute Centers
25000 Undergraduate and 6000 Graduate Students
Top-ranked University in Canada, the Second Best Post-Secondary Institution in North America, and the Ninth Best in the World, among Universities Established After 1964

5. polymer processing group
Directed by Prof. Sundararaj
Areas of Expertise:
Nanomaterial Synthesis (Carbon Nanotube, Metallic Nanowire - Graphene – Graphene Nanoribbon - Nanocaly)
Nanofiller/Polymer Nanocomposite Development and Characterization, i.e. Electrical, Dielectric, Electromagnetic Interference Shielding, Mechanical, Thermal, Rheological, optical, etc.

6. facilities in ppg (cont’d)
Chemical Vapor Deposition Setup (Carbon Nanotube Synthesis)
Nanowire Synthesis Setup
Melt Mixing Equipment at Different Scales: Alberta Polymer Asymteric Miniature Mixer (2 cm3), Haake Mixer Setup (70 cm3), and Coperion Pilot Scale Twin-Screw Extruder
Injection Molding and Compression Molding Setups
TGA and DSC for Thermal Analysis
Electro-spinning Setup

7. facilities in ppg
Electromagnetic Interference Shielding Setup and Broad Range of Resistivity Meters and Impedance Spectrometers
State-of-the-Art Rheometer, Confocal Microscope and Optical Microscope
Dilatometer (Thermal Expansion)
Tensile Tester
Raman Spectrometer
Spin Coater
Cryo-Ultramicrotome Setup

8. what is a polymer composite?!
Composite is a multi-component material comprising different phases, in which one of the phases is continuous.
Polymer composite is a type of composite in which one of the phases is polymer.
Enhanced Properties:
Electrical
Mechanical
Thermal
Optical
Tribological
Rheological

9. Microcomposite versus Nanocomposite
Microfiller
103 nm
Nanofiller
103 nm
〜 1 nm
1 vol.% of Filler in 1 m3 Polymer Matrix
Surface Area = 60,000 m2
Surface Area = 20,000,000 m2

10. conductive filler/polymer composites (CPCs)
Light weight
Low cost
Easy processability
Presenting wide range of electrical conductivity

11. multi-walled carbon nanotube (MWCNT): an outstanding filler for CPCs
sp2 hybrid
High Electrical Conductivity
Outstanding Thermal Stability

12. Semi-Conductive Insulative Conductive Quartz Glass Silicon Copper
Conductive Filler/Polymer Composites
Semi-Conductive
Insulative
Conductive
S/m
10-18
10-12
10-7
10+2
10+8
Quartz
Glass
Silicon
Copper

13. ELECTRICAL CONDUCTIVITY OF CPCs
The percolation curve of MWCNT/polycarbonate composite.1 1
1 Arjmand M, Mahmoodi M, Gelves GA, Park S, Sundararaj U, Carbon, 49, 3430 (2011).

14. Electromagnetic Interference (EMI) Shielding Mechanisms
Incident Power PI
EMI Shielding Mechanisms:
1- Reflection
2- Absorption
3- Multiple-Reflections
PI-R
Reflected Power PR
Transmitted Power PT
SE = 10 · log (PI/PT)
Expressed in dB

15. WHAT MAKES A CPC UNIQUE FOR CHARGE STORAGE?
Nano-Capacitor: Conductive Filler as Nanoelectrode and Polymer Matrix as Nanodielectric

16. WHAT MAKES CPC DIFFERENT FOR USE AS CHARGE STORAGE MATERIAL?
The electric dipole has a magnitude equals to the strength of each charge times the separation between charges.
Interfacial Polarization + + + + - + + + + +
Electronic Polarization

17. Improving conductive network Enhanced EMI Shielding
Deteriorating conductive network Improved Dielectric Properties
Mahmoodi M, Arjmand M, Sundararaj U, Park S. Carbon 2012; 50(4):

18. CONCEPTUALIZATION OF EFFECTS OF ALIGNMENT ON EMI SE+ + - + + + + - + +

19. Desired morphologies to improve emi shielding or dielectric properties of mwcnt/polymer composites
(ii)
(iii)
(iv)
(i) Alignment
(ii) Improving Dispersion
(iii) Incorporation of Secondary (Insulative) Filler
(iv) Using Copper Nanowire Instead of MWCNTs

20. Hierarchy of developing conductive filler/polymer composites

21. Chemical Vapor Deposition (CVD) Setup

23. DIELECTRIC RESPONSE TO APPLIED ELECTRIC FIELD
Interfacial
Log (ε′)
X-Band ( GHz) 3 8 12 15
Log (Frequency (Hz))

24. Doping of Carbon Nanotubes: Why Nitrogen and Boron?

25. Different Types of Nitrogen Bonding in Graphitic Structures
Wei DC, Liu YQ, Wang Y, Zhang HL, Huang LP, Yu G. Nano Lett 2009;9(5):

26. Chemical Vapor Deposition (CVD) Setup

27. Nitrogen-doped (N-CNT) Synthesis Procedure
Incipient wetness impregnation of catalyst precursors (Metal Nitrate and Sulfate Components) onto Alumina Support
Drying (25ºC) - Calcination with air at 350ºC – Reduction with Hydrogen at 400ºC
Synthesis at 750ºC for 2h – Precursor Gases (Ethane and Ammonia) - Carrier Gas (Hydrogen)

28. Transmission Electron Microscopy
Open Channel
Bamboo-Shaped
Bamboo-Shaped

29. N-CNT Growth Mechanism
Reyes-Reyes M, Grobert N, Kamalakaran R, Seeger T, Golberg D, Ruhle M, et al.. Chem Phys Lett 2004;396(1-3):

30. Parameters Affecting Electrical Properties of N-CNT/Polymer Nanocomposite
Synthesis Yield (TGA)
Length and Diameter (TEM)
Crystallinity (Raman Spectroscopy)
Metallicity (Raman Spectroscopy and STS)
Nitrogen Content and Bonding Type (XPS)
CNT Dispersion in Nanocomposite (OM+SEM/TEM)

31. Thermogravimetric Analysis

32. Length and Diameter

33. Nitrogen Content and Nitrogen Bonding Type

34. Percolation Curve

35. Electromagnetic Interference Shielding

36. Co > Fe > Ni Conclusions
N-CNTs grown over different catalysts showed the following order of electrical properties from high to low:
Co > Fe > Ni
Higher electrical properties of (N-CNT)Co was attributed to a combination of high synthesis yield, high aspect ratio, high crystallinity, high metallicity, low nitrogen content and better microdispersion.

37. Conceptualization of Ohmic Loss and Polarization Loss+ + - + +

38. Shieldings by Reflection and Absorption

39. BACK-UP SLIDES

40. Dielectric Properties

41. Polarization Mechanisms Over the X-Band (8.2-12.4 GHz)
Interfacial ×
Dipolar (PVDF Matrix) ×
CNT Polarization Yes
Electronic Polarization Yes

42. EXPERIMENTAL (CONT’D)
Injection Molding
BOY 12A
Polystyrene Masterbatch 20 wt%
(MB )
Blending with Twin-Screw Extruder “Coperion ZSK”
Pure Polystyrene
(Styron® 610)
Compression Molding

43. 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
Levels (set points) of the processing parameters used in the injection molding experiments (EXPs). The processing parameters are mold temperature (C1), melt temperature (C2), injection/holding pressure (C3) and injection velocity (C4).
EXP #
C1 (°C)
C2 (°C)
C3 (bar)
C4 (mm.s-1) 1 60
215
100
240 2 3 24
Parameter
Value (mm) a
22.86 b
10.16
c, d 1 e 2 f 10
1Mahmoodi M, Arjmand M, Sundararaj U, Park S. Carbon 2012; 50(4):

44. Illustration of the effect of nanotube alignment on the appearance of micrograph of mwcnt-aligned samples
Flow Direction
Perpendicular to the flow direction
Parallel to the flow direction
Adapted from Pötschke et al. Eur. Polym. J. 2004;40(1):

45. 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
EXP #1
1.66
1.51
EXP #2
1.53
1.44
EXP #3
1.35
1.27
The order of the Raman intensity ratios, and consequently MWCNT alignment, from the highest to the lowest is EXP #1 > EXP #2 > EXP #3 > compression molded samples.

46. Effects of mwcnt alignment on dc conductivity and emi se
The order of electrical conductivity and EMI SE from the highest to the lowest is compression molded samples > EXP #3 > EXP #2 > EXP #1.
EMI shielding does not require filler connectivity; however, it increases with filler connectivity.

47. Effects of MWCNT alignment on real permittivity and imaginary permittivity
The order of real permittivity and imaginary permittivity from the highest to the lowest is compression molded samples > EXP #3 > EXP #2 > EXP #1.

48. HIERARCHY OF RANDOM DISTRIBUTION OF MWCNTS AND HIGHER EMI SE
Greater Probability of MWCNT Contacts
Greater Electrons’ Mean Free Path
Higher Imaginary Permittivity and Ohmic loss
Higher EMI SE
Higher Applied Electric Field Between MWCNTs
Higher Real Permittivity and Polarization loss

49. Conclusions
The EMI shielding properties of the compression molded samples of MWCNT/PS composites were superior to those of the injection molded samples.
Higher EMI SE in the compression molded samples was related to higher electrical conductivity, real permittivity and imaginary permittivity.
Achieving random distribution of MWCNTs is critical in designing the molds to produce highly conductive injection molded composites.

50. 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

51. CHRONOLOGICAL DEVELOPMENT OF CAPACITORS
Conventional Capacitors like Ceramic Capacitors
High-k Ceramic Powder / Polymer Capacitors
Conductive Filler / Polymer Capacitors (CPCs)

52. STRATEGIES TO AVOID SHARP INSULATOR – CONDUCTOR TRANSITION
Covering the Surface of Conductive Filler with an Insulative Layer
Introducing Secondary Particle as Insulating Barrier

53. The following slides present the results for different processing conditions of injection molding machine.

54. EXPERIMENTAL (CONT’D)
Materials
Masterbatch of multi-walled carbon nanotube (MWCNT) in Polystyrene, Hyperion (MB )
Neat Polystyrene (PS), Americas Styrenics LLC (Styron® 610)
Composite Preparation
Diluting the masterbatch with the neat PS using a Coperion ZSK co-rotating intermeshing twin-screw extruder with a residence time, melt temperature and extruder speed of 2 min, 200 °C and 150 rpm, respectively
Composite Molding
Compression Molding: Carver Plate Press: 210 oC, 38 MPa, 10 min

55. EFFECTS OF MWCNT ALIGNMENT ON SHIELDINGS BY REFLECTION AND ABSORPTION

56. MWCNT ALIGNMENT
&
DIELECTRIC PROPERTIES

57. BASIC PREREQUISITES FOR CAPACITORS
High Dielectric Constant (Real Permittivity)
Low Leakage Current (Imaginary Permittivity)
Process Compatibility with printed circuit board

58. CHALLENGES IN MANIPULATING CPCS AS CHARGE STORAGE MATERIALS
According to the percolation theory, a high real permittivity with a low leakage current is achievable at filler loadings below and close to percolation threshold region.1
The insulator–conductor transition, which occurs at percolation threshold region, precludes CPCs from being used at filler loadings above percolation threshold.
There is a typical narrow insulator-conductor transition window to regulate dielectric properties. This leads to challenges in manipulating CPCs as charge storage materials.
1Dang ZM, Yao SH, Yuan JK, and Bai JB. J Phys Chem C 2010; 114:

59. EFFECT OF ALIGNMENT ON INSULATOR – CONDUCTOR TRANSITION WINDOW
0.7 – 2.0 wt%
5.0 – 8.5 wt%
1 Arjmand M, Mahmoodi M, Park S, Sundararaj U, Compos Sci Tech, 78, 24 (2013).

60. Effects of alignment on real permittivity and imaginary permittivity

61. EFFECTS OF ALIGNMENT ON DISSIPATION FACTOR

62. MORPHOLOGICAL ANALYSIS
Injection Molding
Compression Molding

63. 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
1 Arjmand M, Mahmoodi M, Park S, Sundararaj U, Compos Sci Tech, 78, 24 (2013).

64. CHARGE STORAGE
The electric dipole has a magnitude equals to the strength of each charge times the separation between charges.
Interfacial Polarization + + + + - + + + + +
Electronic Polarization

65. Design of Experiments (Injection Molding Process)
Factors c1 c2 c3 c4 1 - 2 + 3 4 5 6 7 8 9 10 11 12 13 14 15 16
c1: Mold Temperature
c2 : Melt Temperature
c3 : Injection/Holding Pressure
c4 : Injection Velocity
Level
Factors
c1 (°C)
c2 (°C)
c3 (bar)
c4 (mm/sec) + 60
240
100 - 25
215 24
Parameter
Value (mm) a
22.86 b
10.16
c, d 1 e 2 f 10

66. (I) Design of Experiments
Balancing the cavities based on same filling time strategy
Full factorial design of experiments
Exp. #
Factors c1 c2 c3 c4 1 - 2 + 3 4 5 6 7 8 9 10 11 12 13 14 15 16
c1: Mold Temperature
c2 : Melt Temperature
c3 : Injection/holding Pressure
c4 : Injection Velocity
Cavity 2
Fan Gate
Cavity 1
Edge Gate
Cavity 3
Level
Factors
c1 (°C)
c2 (°C)
c3 (bar)
c4 (mm/sec) + 60
240
100 - 25
215 24

67. Experimental design (5.0wt% MWCNT/PS Composites)

69. What Does Make CPC Different For Use As Charge Storage Material
What Does Make CPC 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

72. Impedance Spectroscopy to recognize Conductive Materials
Undoped CNT/PVDF Nanocomposites
N-CNT/PVDF Nanocomposites

73. What Makes Doping Important for Electronic Properties?
Isolator-Metal. Available from:

74. N-CNT Growth Mechanism
Bamboo-Shaped
Fe Catalyst
Open-Channel
Co Catalysts
van Dommele S, Romero-Izquirdo A, Brydson R, de Jong KP, Bitter JH. Carbon 2008;46(1):
Hofmann S, Sharma R, Ducati C, Du G, Mattevi C, Cepek C, et al. Nano Lett 2007;7(3):602-8.