EFFECTS OF HYDROGENATION OF PETROLEUM PITCH ON MESOPHASE FORMATION

The effects of hydrogenation of petroleum pitch on mesophase formation have been studied in terms of the hydrogen donor (D(a)) and acceptor (A(a)) abilities of starting pitch, the temperature dependence of mesophase content, the thermal properties of the resultant mesophase pitches with differential scanning calorimetry (DSC), and C-13-NMR spectra of the mesophase pitches in the liquid and solid states. Hydrogenation of petroleum-derived pitch causes a significant increase of (D(a)) and a clear shift of the mesophase generation temperature to the high-temperature side. Measurement of the characteristics of molecular size for mesophase pitches using DSC has been successfully accomplished. The increase of D(a) due to hydrogenation cause the production of mesophase having a smaller average molecular size and a more homogeneous molecular size distribution. The decrease of molecular size in the mesophase seems to cause the narrowing of the characteristic peak for mesophase around 180 p.p.m. in C-13-NMR spectra in the liquid state.