Introduction Carbon Nanotubes (CNT) are: § Nano-sized cylindrical tubes composed of sheets of carbon atoms
Schematic of a CNT
SEM image of CNT
§ Discovered in 1991 by Sumio Ijima in his study of arcdischarge products CIV4211: Final Year Project
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Introduction § Usually produced by arc evaporation § Exceptional mechanical, thermal and electrical properties § High aspect ratio
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Problem Statement: “CNT-epoxy composite has slightly better mechanical properties than pure epoxy”
Reason: 1. CNT tend to agglomerate and entangle 2. Strong van der Waals attractive force 3. Weak CNT-matrix interaction Solution: Dispersion CIV4211: Final Year Project
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Aims § Study the characteristics of CNT to realize its full potential § Understand the role of carbon nanotube geometry on efficient dispersion § Harnessing the superior properties of nanocarbon in the construction industry
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Learning mechanism
Literature Review
Experiment
Simulation/ Modelling CIV4211: Final Year Project
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Stage 1: Literature Review CNT Properties: § Density: 1.4 to 2.1 g/cm3 Properties
CNT
Young’s Modulus
1000 GPa
CNT Epoxy Composite 1 to 2.7 GPa
Tensile Strength
13 to 53 GPa
1 to 3 MPa
Flexural Strength
13 to 15 GPa
30 to 70 MPa
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Stage 1: Literature Review Composite Characteristics § Reinforcement: High strength of the carbon fibre § Matrix: Epoxy protects CNT § Successful composite requires treatment
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Stage 1: Literature Review CNT Fabrication: § Dispersion Methods: q Chemical: solvent type, surfactant, CNT functionalization q Physical: High speed shear mixing and ultrasonication
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Stage 2: Experiment Aim: Investigate effect of CNT geometry Method 1. CNT mixed with ethanol and surfactant 2. Sonication with a horn sonicator 3. UV-vis method and visual observation 4. Scanning electron microscopy (SEM)
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Stage 2: Experiment Adsorption Spectrum § Peak at about 260nm § Strong absorption by dispersed CNT § Absorbance decreases: Scattering Figure 1: Normalized UV-vis adsorption spectrum of CNT in ethanol at continuous power of 25 W.
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Stage 2: Experiment CNT Diameter § Poor dispersion in small diameter CNT § Smaller diameter = large surface area. § More surfactant molecules needed
Figure 2: Effect of CNT diameter on CNT dispersion in ethanol solvent. CIV4211: Final Year Project
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Stage 2: Experiment CNT Length § CNT length insignificant § TSA:V is independent of length § Van Der Waals
Figure 3: Effect of CNT length on CNT dispersion in ethanol solvent. CIV4211: Final Year Project
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Conference Paper
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Conclusion § Dispersion is key to enhance mechanical properties § Experiment: Fabrication, CNT laboratory testing § CNT geometry o Diameter o Length
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THANK YOU
Questions?
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Glossary
§ Aspect ratio: Ratio of length to diameter in a tube § Surfactant: Substance that promotes dispersion of CNT. In the experiment, dispersing agent was BYK9076, an Alkylammonium salt of a high molecular weight copolymer § Functionalisation: Chemically attach certain molecules (functional groups) to their smooth sidewalls without significantly changing the CNT desirable properties § Shear Mixing: Flow of the medium respond to an external force generates local shear stresses that causing dispersion § Uv-vis: correlates intensity of absorption of UV-visible radiation to the amount of substance present in a solution § SWNT: tubes of graphite that are normally capped at the ends with a single cylindrical wall CIV4211: Final Year Project
