| abstract |
In a process for the manufacture of pitch foams in which pitches are expanded at elevated temperature by a porogenic agent in a mould, the pitch has a KS softening point of from 70 DEG to 210 DEG C. The initial pressure is such that, at the decomposition temperature of the porogenic agent, the external pressure is higher than the pressure which would normally exist within the pitch at the temperature of operation. After the decomposition of the porogenic agent the pressure is lowered to expand the pitch. The temperature may also be adjusted between the decomposition and decompression stages. These pitch foams can be used as floor coverings, as insulators or as surfaces for the collection of solar energy. Certain foams may be converted to carbon and graphite foams by a process of oxidation to render their surface infusible followed by carbonisation and, if desired, graphitisation. The carbon foams can be used as thermal insulation, as catalyst supports or as filters for corrosive products. |