Composite Materials Containing ChemicallyModified Multiwall Carbon Nanotubes

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Composite Materials Containing Chemically-Modified
Multiwall Carbon Nanotubes

• Rodney Andrews, John Anthony, Robert Bergosh,
  Robert Haddon, Chad Landis, Fiona McKenzie, Mark
  Meier and Terry Rantell
• University of Kentucky
• Center for Applied Energy Research
• NSF-MRSEC Advanced Carbon Materials Center

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Objectives

• Nanotube Composite Materials
• Ultrahigh strength-to-weight materials
• Electrically or thermally conductive plastics
• Functionalized nanotubes
• Improved dispersability
• Enhanced nanotube-matrix adhesion
• Better load transfer to nanotubes

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MWNT Functionalization

• Based on known functionalization routes for
  fullerenes
• Functional Groups
• Benzyne (Bz)
• Dichlorocarbene (DClC)
• Diphenylmethylcarbene (DPMC)
• Treated by 1x or 3x reaction

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MWNT Materials

• CVD synthesis
• xylene / ferrocene
• low temperature, 725 oC
• high purity, gt 95

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Shear Mixing of MWNT into Polymers

• Haake Polylab Shear Mixer
• 50 gram charges
• 0 - 1 vol fiber
• Matrices
• PS (280k Mw)
• Mixing Energy

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Dispersion of f-MWNT in PS
Optical Micrograph
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SEM of Fracture Surface
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Film Fabrication

• Post mix material ground to -5mm
• Vacuum hot pressing
• Heated platens
• Teflon mold cloth bagging
• Films
• 1.5mm thick for flexural testing
• 0.2mm thick for tensile testing

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Testing Protocols

• Surface resistance
• ProStat POI-870
• ASTM D257
• Tensile and flexural measurements
• MTS QT1/L
• ASTM D790
• ASTM D882
• ASTM D638

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Surface Resistivity of MWNT/Polystyrene
Composite Films
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Flexural Modulus of MWNT/Polystyrene Films
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Flexural Strength of MWNT/Polystyrene Films
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Tensile Modulus of MWNT/Polystyrene Films
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Tensile Strength of MWNT/Polystyrene Films
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Conclusions

• Functionalization did not impair electrical
  conductivity (1vol 103 Ohm/square)
• Significant increase in tensile and flexural
  moduli compared to unmodified MWNTs
• Effect on strength not clear
• MWNT ends act as defect sites
• Improvement in nanotube-polymer interface
• f-MWNT yield composite stronger than native
  polymer

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What next?

• Optimized functional group - polymer systems
• Copolymerizations of f-MWNTs
• Aligned MWNT reinforcements
• 2D and 3D ordering

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Acknowledgements