Carbonization of various precursors. Effect of heating rate Part I: Optical microscopy studies

During carbonization anisotropic domains, i.e. local molecular orientation (LMO), occurs. Their final size coincides with resolidification, fixing up the further properties of carbons. Five samples [pitch (Ashland 240), heavy petroleum products and kerogen increasingly cross-linked by oxygen] were studied by optical microscopy after heat treatment at increasing heating rates (0.5 degrees C min(-1) and 4 degrees C min(-1)). Anisotropy suddenly occurs after softening and before solidification at an increasing HTT as the heating rate increases. Anisotropy also occurs at decreasing HTT from pitch (A240) to heavy petroleum products. Anisotropic domain sizes increase up to solidification (local molecular orientation) from petroleum products to pitch. (C) 1999 Elsevier Science Ltd. All rights reserved.