The influence of primary quinoline insolubles on the development of secondary quinoline insolubles in coal tar pitches

Abstract

The development of secondary quinoline insolubles (2°QI) or mesophase has been studied by heat treating four different, commercially available coal tar binder pitches to a series of predetermined temperatures and hold times. The development of the 2°QI is discussed in terms of the shape and amount of the primary quinoline insolubles (1°QI) initially present in each pitch by examination of scanning electron micrographs of the extracted quinoline insolubles. The development of the 2°QI of these materials is compared with the development of 2°QI in a petroleum pitch where 1°QI is initially absent. Small, laboratory extruded graphite rods using each of the four binder pitches were produced in order to examine the influence of 2°QI development on typical graphite properties.