抄録
The present investigation was undertaken to know the effect of chemical structures of pitches on the formation and the growth of spherical bodies observed in the early stage of carbonization of pitches. Naphtha tar pitch of which chemical structure differs from that of naphtha tar pitch used in a previous paper (the former and the latter shall be hereafter called as naphtha tar pitch-2 and naphtha tar pitch-1, respectively) was fractionated by n-hexane, acetone, and benzene into three fractions of No.1, No.2, and No.3. Each fraction was carbonized to examine its spherical bodies by polarized-light microscope.
The structural parameters for each fraction were estimated from elemental analysis, molecular weight and hydrogen distribution determined by NMR spectra. The aromaticity and the degree of substitution of the aromatic system of each fraction were found ranging from 0.76 to 0.79 and from 0.22 to 0.25, respectively. Although the formation and the growth of spherical bodies in fractions of naphtha tar pitch-2 were easy in a similar order of No.3 to No.1 to those in naphtha tar pitch-1 and coal tar pitch as described in a previous paper, they were easy compared with the same fractions in naphtha tar pitch-1 and coal tar pitch. Furthermore, the interlayer spacing, the size of crystallite and the coefficient of thermal expansion were observed in order to compare the characteristics of cokes obtained from each fraction.
