This presentation reviews the Good, the Bad and the Ugly side of Carbon Nanotubes. The presentation was given at the Ecole Centrale Nantes in 2011

1. Carbon Nanotubes (CNTs)
The Good
The Bad
& the Ugly
Malcolm Mackley, Anson Ma, Kat Yearsley
Department of Chemical Engineering and Biotechnology

2. The Carbon Family
Graphite Graphene Diamond CNT
Carbon Black
2

3. CNTs; “The Good”
Super potential properties
Stiffness
CNT 1000 GPa
(steel 210 GPa)
Electrical Conductivity
CNT 106 10 S /m
7
(Copper 6 107 S /m)
Thermal Conductivity
CNT 3500 W/m
K
(Copper 385 W/m
K) 3

4. CNTs; “The Bad”
health risk
University of Cambridge
Health and Safety Office
HSD060C
July 2009
Carbon nanotubes and other insoluble fibrous
nanoparticles that have the potential to become
airborne should be handled under HEPA‡
filtered local exhaust ventilation (LEV).
‡ High Efficiency Particulate Air (HEPA)
4

5. CNTs; “The Ugly”
Dispersion
5

6. Dispersion matrix
• Epoxy resin*
10Pas or 1 Pas SWNT, MWNT
• UV curing acrylic precursor*
• Thermoplastic Polypropylene (PP)
Nanocyl (Compounding required)
• Agarose/water*
Carboxyl Methyl Cellulose (CMC )“surfactant” required
• Fuming Sulphuric acid (LCP form)
Matteo Pasquali ( Rice University, Houston Texas)
* Personal involvement
6

7. Dispersion devices
 Batch Stirred vessel; design, scale, feed
protocol*.
 High shear mixer*.
 Ultra sound mixer; Biorupter, Nanorupter*.
 Compounding device (Nanocyl)
 Twin screw extruder (Nanocyl)
* Personal involvement
7

8. Best method of Mixing ?
 Simple shear
 Extension
 Stretch and Fold or Mixed flow
 “Vibration”
8

9. MWCNT vs Carbon Black (CB)
0.25 wt% CNT in epoxy 0.25 wt% CB in epoxy
Kat Yearsley
9

10. Optical Observation of
Untreated Multi-Walled CNT
The Linkam, Cambridge Shear System CSS
10

11. Microstructure
• Optical Microscope combined with shear cell
• Isotropic CB vs. Anisotropic CNTs
Images Recorded
100
Shear Rate (s-1)
10
0.5
15 mins 10 s 10 s
11

12. 0.25% CB in epoxy
12

13. 0.25% CNTs
13

14. CB after low shear: CNT after low shear:
Aggregation Aggregation
Flow Flow
CB after high shear: CNT after high shear:
Disaggregation Disaggregation & alignment
Flow Flow 14

15. The “Zoo” of CNT Microstructure
0 s-1 1 s-1 10 s-1 100 s-1 1000 s-1
I. Untreated
SWNT
II. Treated
SWNT
III. Untreated
MWNT
IV. Treated
MWNT
All at 0.05 wt% conc 15

16. Steady Shear (SS) Experiments
CB CNT
1000
1000 1000
100
100 100 0.4%
4% 4% 0.3%
η η 10 2% η
(Pa.s)10 10 0%0%1%1%2%2%4%4%
Pa.s) 3% (Pa.s) 0.2%
1%
1 1 2% 1
0%
0% 0%
0.10.1 0.1
0.10.1 1 1 10 10 100 0.1
100 1 10 100
Shear Rate (/s)
Shear Rate (/s) Shear Rate (/s)
16

17. Aggregation/orientation model , Paco Chinesta
Diffusion equation
∂  dρ  ∂  ∂ψ (ρ, n )  ∂ψ (ρ, n ) ∂ 2ψ (ρ, n )
− ψ (ρ, n )  +  Dr ( n )  − 3vn + Dn =0
∂ρ  dt  ∂ρ  ∂ρ  ∂n ∂n 2
Where
n is population from n = 0 to n = 1
.
βα = vd vc vn = v c − vd Dn = vd n + vc (1 − n )
,
Destruction rate due to shear creation rate
Constitutive equation
σ = − p I + 2η D + 2ηN p a : D
17

18. (a) 0.25% CNT (b) 0.1% CNT
1000 1000
ηa 100 ηa 100
[Pa.s] [Pa.s]
10 10
0.1 1 10 0.1 1 10
Shear rate [s -1] -1
Shear rate [s ]
(c) 0.05% CNT (d) 0.025% CNT
100 100
ηa 10 ηa 10
[Pa.s] [Pa.s]
1 1
0.1 1 10 0.1 1 10
Shear rate [s -1] Shear rate [s -1]
18

19. CNT Fibre makers
 Pasqualli Group Rice University Houston
 Windle team Cambridge University
19

20. Rice University Houston.;
Anson Ma and Matteo Pasquali, Oct 2010
20

21. TRUE SOLUTIONS OF SWNTs
1 min 10 min 60 min
CNTs dissolve spontaneously
in chlorosulfonic acid
Davis, Pasquali, et al, Nature Nanotech, 4, 830, 2009
21
Pasquali et al, US Patent Application under review (2009)

22. BEHAVIOR AT HIGH CONCENTRATION
12% vol SWNT in chlorosulfonic, CROSS POLARS
co
hi ntra
nc
gh t
e
er ion
ISOTROPIC
CONCENTRATED
LIQUID
CRYSTALLINE
analyzer
-60
-45OOOO
-75
-30O 50 µm
0O
-15
polarizer Davis, Pasquai, et al, Nature Nanotech, 4, 830, 2009
22

23. SPINNING NEAT SWNT FIBERS
Ericson, Pasquali, Smalley, et al., Science, 305, 1447 (2004)
Smalley, Pasquali, et al., US Patent 7,125,502 (2006)
Davis, Pasquali, et al., Nature Nanotech., (2009)
Pasquali et al., patent application under review 23

24. TYPICAL ACID-SPUN SWNT FIBER
Ø=37±3µm
Ø=50±2µm
Sub-optimal mesostructure (bundles), affect transport
Excellent macrostructure 24
Wang, Pasquali, Smalley, et al., Chem. Mater., 17, 6361 (2005)

25. SPINNING FROM CHLOROSULFONIC ACID
7 WT% SWNT in chlorosulfonic 7 wt% SWNT in 7 wt% SWNT in
acid, coagulated in 96% H2SO4 chlorosulfonic chlorosulfonic
13 µm acid: Solvent acid, coagulated in
evaporation dichloromethane
30 µ m 100 µm 100 µm
1 µm 1 µm 1 µm
• Smooth, compact fibers
via slow coagulation
• Coagulants: dichloromethane,
chloroform, ether, sulfuric acid (96%)
25
Davis, Pasquali, et al, Nature Nanotech, 4, 830, 2009

26. Carbon Nanotube Fibres and
their Composites
Alan Windle
And
Team
acromolecular
aterials
ab
New Museums Site, Pembroke Street
Cambridge, CB23QZ, UK

27. Fibre spinning in furnace
H2
Ethanol or Hexane
Ferrocene 2%
Thiophene 0.3%
Nanotube
1100 - 1300`°C
Smoke
Its elastic!
an aerogel
Ya-Li Li, Ian Kinloch and Alan Windle,
Science, 304, p 276, 9 April 2004
27

28. Department of Materials, Cambridge,
Injection system
Reactor
Gas exchange valve
Fibre collection
28

29. Continuous wind up with
drawing (10 - 50 m/min)
n.b. 20m/min at 0.05 tex is only 1mg/min or ~ 1g/day
29

30. The knot test; (Get Knotted)
Tensile strength not
degraded by presence
of a knot.
c.f. For carbon fibre
with a knot, strength
can be only 10 % of
unknotted sample
30

31. Wide angle X-ray of fibre
ESRF synchrotron source Grenoble
002
Winding rate = 20 m/min Winding rate = 30 m/min
Very good orientation of CNTs, graphitic component
Unoriented
31
but an unoriented component (particles ?)

32. Carbon nanotube fibre properties
Physical: Specific Gravity 0.5 – 1.1
(Diameter 10 micron)
Mechanical: Strength 0.5 - 2.3 GPa/SG
Stiffness 20 – 80 GPa/SG
Thermal: Conductivity 50 – 1000 Wm -1K-1
Electrical: Conductivity 8 x 105 S/m
(no influence of sample length, but only 1/60 of
copper or 1/8 on a unit mass basis). Mix of metallic and
32

33. Carbon nanotube fibres
Carbon fibre Polymer fibres
Carbon
A new sort
Nanotube
of stuff ?
Fibres
Yarns
33

34. Conclusions
•CNTs (still) have exciting potential.
•Handle with care.
•Dispersion still a challenging problem.
Next generation
Composite reinforcement ?
“Carbon Fibre” ?
34

35. The problem! Polymers - CNTs
Molecular dynamics simulations of entangled polymers (or maybe CNTs?)
Prof Aleksei Likhtman (University of Reading)
35