Carbon Nanotube Composites Presentation by Jason Morejon What

Carbon Nanotube Composites Presentation by Jason Morejon • What are CNT Composites? • How do they work? • What affects how well they work? • Improvement Methods • Measured Effects

What are CNT Composites? • “Distinct” molecules forming a single component • Motivation for using composites • Size • Price of CNTs • Large scale production • Current uses for CNT Composites

How do they work? • Matrix and Reinforcement • Connective forces • van der Waals forces • Covalent bonding • Shared Properties • Mechanical Load • Thermal, Electrical conduction Nanotube in Polypropylene Sandler et al, J Macro. Mol Science B, B 42(3&4), pp 479, 2003

What affects how they work? • Matrix substance • Concentration • Dispersion • Orientation • Anisotropic material • Type of nanotube • SWNT and MWNT • Surface area vs volume • Defects in nanotubes • Metallic and Semiconductive M. J. Biercuk, M. C. Llaguno, M. Radosavljevic, J. K. Hyun, A. T. Johnson Applied Physics Letters 80 (2002) p. 2767

Improvement Methods • Polycarbonate wrapping of MWNT • Plasma deposition of 2 -7 nm polystyrene • Improved dispersion • Increased tensile strength and modulus • Clearly defined interfacial adhesion layer Ding W. , et al, Direct observation of polymer sheathing in carbon nanotube polycarbonate composites. Nano Letters, 2003. 3(11): p. 15931597

Improvement Methods • Dispersion • Overcoming van der Waals interactions • Easier with MWNT (less aggregation due to size) • Alignment • Shown to improve mechanical properties and electrical and thermal conductivity • Ultrasonic dispersion, Melt processing, electrospinning, electric fields, mechanical shear

Alignment - electrospinning • Forced out by pump • Held together by viscosity (or breaks into droplets) • Kept thin by electrostatic repulsion • Produces nanometer-scale diameters of uniform fibers http: //en. wikipedia. org/wiki/Electrospinning

Measured effects Unaligned Aligned M. J. Biercuk, M. C. Llaguno, M. Radosavljevic, J. K. Hyun, A. T. Johnson Applied Physics Letters 80 (2002) p. 2767 Improvements to a polypropylene matrix due to various percentages of added carbon nanotubes

Measured Effects • For 1% CNT a 5 th-order decrease in resistivity achieved • For Melt Blended CNT a 50% and 60% increase in modulus was achieved for 5% and 10% respectively • A tensile strength of 1. 8 GPa has been reached (stronger than steel or spider silk)

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