AN ATTEMPT TO CHARACTERIZE AND ELABORATE ANISOTROPIC PITCHES AND DERIVED CARBON-FIBERS .1. PREPARATION BY BUBBLING

Gas-sparge process was approximated by bubbling. Heterogeneous anisotr opic pitch was prepared by pulsing bubbles of nitrogen in an isotropic pitch Kraemer-Sarnov point (KS 70-degrees-C) thermally evolving (irre gular bubbling). It was compared to laboratory and industrial, B, B1,. ..B3 pitches. All of them are mixtures of isotropic phase 1 containing Brooks and Taylor mesophase spheres with an edge-to-edge type of gel 2-3. The latter is a two-phase disperse system made of a major anisotr opic component 2 including orthogonally oriented microdroplets 3. The gel 2-3 is quinoline-soluble but toluene insoluble (QS.Tl) (i.e., beta resins). From B, B1 to B3, the amount of phase 1 increases and become s the major component in B, and B3. A more steady stirring yields a pi tch C1 free of isotropic phase 1 and identical to the industrial pitch C. Heterogeneous pitches yield poor heterogeneous fibers. The pure ge l 2-3 pitch yields improved fibres. After graphitization, the cross se ctions are entirely full of nano zig-zag issued from 2-3. The larger t he grains, forming (in projection) the linear parts of the zig-zag, th e better the graphitizability.