A New Production Route for Tailor-Made Buckypaper

Buckypaper are self-supporting films of carbon nanotubes (CNT), which can be used as electrodes, nano filter or for the reinforcement of polymers, for instance. Usually they are produced by filtration of CNT dispersions. The disadvantages of filtration process are discontinuous operation, long duration of filtration and limited size of the buckypaper. The aim of this project was to develop a special tape casting process for buckypaper production. Due to the small particle size and high aspect ratio of the CNT, the maximum CNT content in castable dispersions is limited to 3 wt. %. This leads to low layer thicknesses, high shrinkages and high crack formation during the drying of casted films. To increase the buckypaper thickness, a multi-layer tape casting process has been developed. For the production of buckypaper, water based CNT dispersions have been used. Rheological and zeta potential measurements have been used for characterization of CNT dispersions. The influence of casting parameters on the films was investigated by using design of experiments. The films were examined according to thickness, bulk density, porosity and electrical conductivity.