Rheological investigations of pitch material - Part II: viscosity measurement of A240 and ARA-24 pitches using a high-temperature high-pressure rheometer

Fluid behavior of carbonaceous pitch materials, such as A240 and ARA-24; is evaluated using the high-temperature, high-pressure (HTHP) viscometer. The measured viscosity of A240 pitch using the HTHP viscometer shows excellent agreement with that obtained using a Brookfield viscometer (DV III+). Furt her, the viscosity of ARA-24 (mesophase) pitch is measured and reported as a function of temperature at elevated temperature. Finally, the viscosity o f pitch materials, both A240 and ARA-24, is modeled using the modified Will iam-Landel-Ferry (WLF) equation. The shear activation energy for the 100% m esophase pitch (ARA-24 pitch) increased with the shear rate while that for the A240 pitch remained constant. Moreover, the shear activation energy for ARA-24 pitch was higher than that for A240 pitch at the shear rates invest igated. (C) 2000 Elsevier Science Ltd. All rights reserved.