Production of mesophase by pyrolysis

Reprinted with permission from Hornby J, Kearsey HA, Carbon fibres from pitch precursors 2. The preparation of mesophase pitches suitable for spinning into fibres, AERE Harwell report AERE-M 3029, Oct 1979. Copyright 1979, AEA Technology pic. 

Sparge of an inert gas, which continuously removed the highly volatile components, effectively producing a single phase product, which was 100% mesophase, with over 90% having a molecular weight less than 1500. 

A later modification of this process, used in Japan, yielded a less viscous product achieved by cooking at a slightly lower temperature and allowing the heavier mesophase pitch (about 70-80% mesophase) to settle out by standing and then collecting by centrifuging. 

Union Carbide [243] claims that a pitch suitable for spinning should preferably contain 40-90% mesophase, with domain sizes greater than 200 pm, which will then produce a fiber with a highly oriented structure. Domain sizes below 100 pm produce stringy clumps, unsuitable for spinning. When the droplets coalesce to form the bulk mesophase, some 

The effect of mesophase pitches on the tensile modulus of the resultant pitch based carbon fiber has been studied [245] and carbon fiber prepared from an isotropic pitch containing mesophase spheres has also been studied [246], 

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