[Review] Mechanical properties of CNT-Polymer composite - Part 1

I. INTRODUCTION
1. Advantage of CNT in polymer
 - Good (thermal, ellectrical) conductivity
 - High aspect ratio
 - Low percolation threshold
 - (Small dimensions =>) High surface area => Great interaction with composite matrices
 - Impressive mechanical properties with Young's modulus in the range 100 - 1000 GPa and strengths between 2.5 and 3.5 GPa
2. Parameter of CNT
 - Diameter ranges from 1 to 100 nm
 - Lengths of up to millimetres
 - Density ~ 1.3g/cm3
 - Highest measured strength was 63GPa
3. Properties of CNT
 - Two main types: Single walled nanotubes (SWNT) - diameter 1nm, Multi-walled nanotubes (MWNT) - diameters 2~100 nm
 - The most common synthetic: laser ablation, chemical vapor deposition (CVD) and in particular, decomposition of CO

A graphene sheet may be rolled up in many ways to form a single walled nanotube. The rolling action breaks the symmetry of the planar system and imposes a distinct direction with respect to the hexagonal lattice, the axial direction. Depending on the relationship between this axial direction and the unit vectors describing the hexagonal lattice, the tube can be metallic, semi-metallic or semi-conducting. Semi-conducting nanotubes have bandgaps that scale inversely with diameter, ranging from approximately 1.8 eV for very small diameter tubes to 0.18 eV for the widest possible stable SWNT

 - One-dimensional nature => charge carriers can travel through nanotubes without scattering => CNT are extremely conductive [The absence of scattering means that Joule heating is minimised so that nanotubes can carry very large current densities of up to 100 MA/cm2]

Semi-conducting nanotubes: carrier mobilities as high as 100.000cm2/Vs

Thermal conductivity: around 200 W/m K