BIFURCATION BEHAVIOUR OF EXTRUSION OF LIQUID CRYSTALLINE POLYMER MELT-ANISOTROPIC VISCOELASTIC FLUID
液晶高分子-各向异性流体挤出拉伸分岔研究

Using the constitutive equaiton of co-rotational derivative type for LC polymer melt, the extrusion process of LC polymer melt is investigated. The extrusion process near the die exit of the fiber spinning is represented by a viscometric-extensional flow. Using the computational symbolic manipulation software Maple, analytical expressions of the elongational viscosity are derived. The relationship between elongational viscosity and extension rate under varying shear rate shows bifurcation behaviour and considerable increase of elongational viscosity, when the orientational motion of the director vector is considered. The contraction of extrudate is caused by the high elongational viscosity for LC polymer melt, which is a rheological explanation of anti-die swell of LC polymer melt in extrusion process.