Rheological Properties and Shear Induced Texture Development of Thermotopic Liquid Crystalline Polymer Melts

Abstract

The flow behavior of two commercial liquid crystalline polymers (LCPs), trade name Vectra B 950 and Vectra L 950 supplied by Ticona, was investigated using a capillary rheometer with a special double slit die. The pressure drops in convergent and divergent wedge passage between the two slit sections, which are influenced by the curvature strains in nematic melts, were determined and compared with the pressure drops of a conventional polystyrene (PS) with flexible polymer chains. Furthermore the extensional viscositiy was determined from the pressure drop in convergent wedge passage. The development of the shear induced texture as a function of shear rate was investigated by use of a rapidly coolable double slit die with the same gap design as the double slit die used for viscosity measurement. The structural analysis was performed using polarized light microscopy.

Keywords

• liquid crystalline polymers (lcps(
• capillary rheometer
• convergent flow
• shear induced texture
• polarized light microscopy