Some Rheological Measurements on Coal Tar Pitches

Abstract (1) Visco-elastic properties of tar pitches in the softening range were measured by a dynamic method covering 3∼20 minutes of period. (2) No frequency dependence of viscosity was observed in this range of period. (3) Elastic effect was slight in this range of period. Its frequency dependence was appreciable. (4) Tar pitch is a simple Maxwellian body rheologically above the softening point. (5) Temperature dependence of viscosity was studied along the rate-process theory, and it was supposed that tar pitch has a highly associated or solvated structure, consistent with the present theory of the internal structure of coal.