Fractionation of Polyvinyl Chloride Pitch by Vacuum Sublimation

Pitch prepared by heating polyvinyl chloride at 400 °C (PVC pitch) was fractionated by vacuum sublimation. The fractions were studied by means of elementary analysis, determination of molecular weight, IR spectroscopy and NMR spectroscopy. It was found that each fraction has a characteristic constituent as follows: 1) Zones 1 and 2 are composed of some aromatic nuclei with 3–4 rings and 3–5 rings linked with aliphatic chains, respectively; 2) Zones 3 and 4 are composed of condensed aromatic nuclei with 6–8 rings and 6–7 rings, respectively; 3) In zone 5, aromatic nuclei have 2–4 aromatic rings on an average, and the ratio of the aliphatic group is higher than that of other zones; 4) The sublimation residue is mainly composed of condensed aromatic nuclei, and the ratio of aromatic hydrogen to aliphatic hydrogen in the residue is the highest.