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CNT Nantes- 2011

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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

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CNT Nantes- 2011

  1. 1. Carbon Nanotubes (CNTs)The Good The Bad& the Ugly Malcolm Mackley, Anson Ma, Kat Yearsley Department of Chemical Engineering and Biotechnology
  2. 2. The Carbon FamilyGraphite Graphene Diamond CNT Carbon Black 2
  3. 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/mK (Copper 385 W/mK) 3
  4. 4. CNTs; “The Bad” health risk University of Cambridge Health and Safety Office HSD060C July 2009Carbon nanotubes and other insoluble fibrousnanoparticles that have the potential to becomeairborne should be handled under HEPA‡filtered local exhaust ventilation (LEV). ‡ High Efficiency Particulate Air (HEPA) 4
  5. 5. CNTs; “The Ugly” Dispersion 5
  6. 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. 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. 8. Best method of Mixing ? Simple shear Extension Stretch and Fold or Mixed flow “Vibration” 8
  9. 9. MWCNT vs Carbon Black (CB)0.25 wt% CNT in epoxy 0.25 wt% CB in epoxy Kat Yearsley 9
  10. 10. Optical Observation ofUntreated Multi-Walled CNT The Linkam, Cambridge Shear System CSS 10
  11. 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. 12. 0.25% CB in epoxy 12
  13. 13. 0.25% CNTs 13
  14. 14. CB after low shear: CNT after low shear:Aggregation AggregationFlow FlowCB after high shear: CNT after high shear:Disaggregation Disaggregation & alignmentFlow Flow 14
  15. 15. The “Zoo” of CNT Microstructure 0 s-1 1 s-1 10 s-1 100 s-1 1000 s-1I. Untreated SWNTII. Treated SWNTIII. Untreated MWNT IV. Treated MWNT All at 0.05 wt% conc 15
  16. 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. 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. 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. 19. CNT Fibre makers Pasqualli Group Rice University Houston Windle team Cambridge University 19
  20. 20. Rice University Houston.;Anson Ma and Matteo Pasquali, Oct 2010 20
  21. 21. TRUE SOLUTIONS OF SWNTs 1 min 10 min 60 min CNTs dissolve spontaneously in chlorosulfonic acidDavis, Pasquali, et al, Nature Nanotech, 4, 830, 2009 21Pasquali et al, US Patent Application under review (2009)
  22. 22. BEHAVIOR AT HIGH CONCENTRATION 12% vol SWNT in chlorosulfonic, CROSS POLARS co hi ntra nc gh t e er ion ISOTROPICCONCENTRATED LIQUID CRYSTALLINE analyzer -60 -45OOOO -75 -30O 50 µm 0O -15 polarizer Davis, Pasquai, et al, Nature Nanotech, 4, 830, 2009 22
  23. 23. SPINNING NEAT SWNT FIBERSEricson, 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. 24. TYPICAL ACID-SPUN SWNT FIBER Ø=37±3µm Ø=50±2µmSub-optimal mesostructure (bundles), affect transportExcellent macrostructure 24 Wang, Pasquali, Smalley, et al., Chem. Mater., 17, 6361 (2005)
  25. 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. 26. Carbon Nanotube Fibres andtheir Composites Alan Windle And Team acromolecular aterials ab New Museums Site, Pembroke Street Cambridge, CB23QZ, UK
  27. 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. 28. Department of Materials, Cambridge, Injection system Reactor Gas exchange valveFibre collection 28
  29. 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. 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. 31. Wide angle X-ray of fibre ESRF synchrotron source Grenoble 002 Winding rate = 20 m/min Winding rate = 30 m/minVery good orientation of CNTs, graphitic component Unoriented 31but an unoriented component (particles ?)
  32. 32. Carbon nanotube fibre propertiesPhysical: Specific Gravity 0.5 – 1.1 (Diameter 10 micron)Mechanical: Strength 0.5 - 2.3 GPa/SG Stiffness 20 – 80 GPa/SGThermal: Conductivity 50 – 1000 Wm -1K-1Electrical: Conductivity 8 x 105 S/m (no influence of sample length, but only 1/60 ofcopper or 1/8 on a unit mass basis). Mix of metallic and 32
  33. 33. Carbon nanotube fibresCarbon fibre Polymer fibres Carbon A new sort Nanotube of stuff ? Fibres Yarns 33
  34. 34. Conclusions•CNTs (still) have exciting potential.•Handle with care.•Dispersion still a challenging problem. Next generation Composite reinforcement ? “Carbon Fibre” ? 34
  35. 35. The problem! Polymers - CNTsMolecular dynamics simulations of entangled polymers (or maybe CNTs?) Prof Aleksei Likhtman (University of Reading) 35

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