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.degree. to 210.degree. 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.

Abstract: The invention relates to a process for the manufacture of carbon and/or graphite fibres from natural organic fibres, obtained particularly from the distillation residues of coal or petroleum, by irradiation by microwaves.The process according to the invention consists in subjecting the fibres to a preparatory thermal treatment up to a temperature of between 300.degree. and 1500.degree. C. in an inert atmosphere, for example of nitrogen, argon, helium or hydrogen and then irradiating them with microwaves.The microwaves may have frequencies between 900 and 30,000 MHz and preferably between 2000 and 15,000 MHz and use a power of between 10W and 30kW and preferably between 50W and 10kW. The irradiation is preferably also in an inert atmosphere, for a period ranging from 10 seconds to 15 minutes. The fibres may be oxidized for example in an atmosphere of oxygen, ozone or air up to a temperature of between 100.degree. and 250.degree. C. before the preparatory thermal treatment.