- Carbon nanotube,Purity: 99.9% Diameter: 150-200 nm (from HRTEM, Raman) Length: 10 – 20 microns (Transmission Electron Microscope) Aspect Ratio: 70 Graphitization: > 80% Thermal Conductivity: K>1600w/mk Area: 300 square meters m/g (BET) Thermal conductivity: ~ 2000 W/m Thermal expansion coefficient: 1.0ppm/℃ Bulk density: 0.18g/cm3 ~ True density: 2 g/cm3, 5g