A pressurized filtration technique for fabricating carbon nanotube buckypaper: Structure, mechanical and conductive properties

Abstract

Self-supporting carbon nanotube (CNT) buckypaper has unique structural and conductive properties which can be utilized in various applications. A pressurized filtration technique was developed to fabricate the buckypaper, and tailor its porous structures and properties. Compared with the conventional vacuum filtration technique, the pressure applied in the pressurized filtration process increased from 1atm to as high as 12atm. Filtration behaviors of the CNT solutions during the vacuum and pressurized filtration processes were studied. The results indicated that the filtration behaviors were largely dependent of the applied pressure. Micro-morphologies of the buckypaper were also characterized and appeared to be corresponding to the filtration behaviors well. Upon applying high pressure during the filtration, porosity of the buckypaper was reduced slightly by ∼1.9% due to the flexibility of the porous CNT network structure. Dimensions of the gaps within the interior of highly intermingled CNT bundles or junctions also decreased, resulting in higher intertube interactions. The higher intertube interactions improved the overall mechanical properties, as well as electrical and thermal conductivities of the buckypaper significantly.