Structure and gas permeability of multi-wall carbon nanotube buckypapers

We report on the filtration behavior, scanning electron microscopy (SEM) and gas permeability of multi-wall carbon mats (buckypapers). The SEM-apparent macropore diameter, image fractal dimension and lacunarity (a measure of translational invariance) of the samples averaged at 38 nm, 1.82 and 0.55, respectively. Their N2 adsorption analysis revealed an average BET specific surface area of 197 m2/g, BJH pore diameter of 2.67 nm and FHH fractal dimension of 2.492. These parameters were rather insensitive to the preparation conditions. The effective diffusivity of six common laboratory gases (O2, N2, H2, He, CO2, CH4) through buckypapers of different thicknesses was also measured. Results fell into the 3–12 × 10−9 m2 s−1 range and correlated with the kinetic diameter of the gases.