THE EFFECT OF TEXTURE ON THE SHEAR RHEOLOGY OF A THERMOTROPIC LIQUID CRYSTALLINE POLYMER

摘要

The effects of annealing time and temperature on the transient shear rheology of a thermotropic liquid crystalline polymer are reported. During flow startup, the first shear stress maximum and shear stress minimum was found to depend on annealing time, temperature, whereas the second shear stress maximum, a true overshoot, depends on the temperature, but not on annealing time. In situ rheo-optical characterization revealed that the evolution of the melt texture depends on the annealing time and temperature. We confirm that the threaded texture leads to the generation of the local shear stress maximum and shear stress minimum during shear flow startup.