Preparation of isotropic pitch precursors for general purpose carbon fibers (GPCF) by air blowing—I. Preparation of spinnable isotropic pitch precursor from coal tar by air blowing

✍ Scribed by Toyohiro Maeda; Shu Ming Zeng; Katsuhisa Tokumitsu; Juji mondori; Isao Mochida

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 733 KB
• Volume: 31
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(93)90127-v

✦ Synopsis

A QI-free coal tar pitch with a softening point around 80°C was air blown in an autoclave at 330", 360", and 38O"C, respectively, for various periods in order to prepare a pitch precursor for GPCF. Air blowing markedly increased the softening point and contents of solvent insoluble fractions such as BI, QI. as well as atomic C/H ratio. The pitches blown at 360°C for 2 to 4 h showed excellent spinnability into thin fibers of 12 to 14 pm in diameter at a wide range of 255" to 330°C. Structural characterization by NMR, FT-IR, and elemental analysis on the blown pitches showed that d~stillat~~)n of lighter fractions, aromatization, and polymerization of the remaining fractions due to oxidative dehydrogenation raised their softening points. Although all blown pitches stayed completely isotropic, further heat treatment at 380°C under Nz Aow for 14 to 21. h allowed generation of mesophase spheres in the isotropic matrix. After the carbonization at 600°G, all pitches showed anisotropic texture, suggesting that blown pitches maintain fusibility and reactivity to follow the growth and development of mesophase spheres in the successive carbonization.