Application of microcapsulation technology to the preparation of carbon foam

Microcapsules were prepared by in situ polymerization and microcapsulation. Tetraethyl orthosilicate was used as the core material and phenolic resin was used as the wall material in an emulsion system of polyacrylic and tetraethyl orthosilicate. The obtained microcapsules were slowly heated such that the core material was released by evaporation, leaving hollow-core spheres. The spheres were mixed with a phenolic resin-derived binder and molded to obtain a carbon foam precursor, which was carbonized at 1100°C under the protection of N₂ gas and graphitized at 2300°C under the protection of Ar gas. Thus, the carbon foam of hollow closed-shelled microspheres with a graphitic structure was prepared. The properties and structure of this foam were discussed.