Highly oriented porous graphite film prepared from porous aromatic polyimide film

Porous aromatic polyimide films of 28 and 59 μm thickness and with about 50% porosity (PAPIF-28 and -59) were carbonized and then heat-treated to various temperatures up to 3000 °C, and their texture and graphitizability were investigated. A porous texture on the micrometric scale remained on the surfaces and inside the heat-treated PAPIF-28 and -59 films but the 3000 °C-treated PAPIF-28 film was not porous and showed a dense and fine texture. These heat-treated films, except the 3000 °C-treated PAPIF-28 film, exhibited high permeability to gases and alcohols. The carbonized films of PAPIF-28 and -59 were graphitized by 1 min heat-treatment at 2700 and 2800 °C, respectively and exhibited an approximately planar orientation of carbon layers along each film surface, even though the films had porous textures. However, the graphitization degrees of the porous carbon films derived from PAPIF-28 and -59 were much lower than those of carbon films derived from Kapton, Novax and PPT films.