For both LCP melts investigated, the pressure profiles along both slit section of the convergent as well as of the divergent die were found to be linear for all shear rates (Fig.
On the contrary, in the divergent die configuration the influence of pre-shearing and die geometry on the viscosity are in the same direction, so that the viscosity is found to be lower in the second slit die with the larger gap size (see Fig.
On the other hand, the divergent die and the convergent one cause the stretch and the compression in a tangent direction near the die exit, respectively.
On the other hand, the uniaxial elongation is dominant for the flow of the divergent die at the upper stream region and the biaxial elongation is dominant near the die exit.
However, the numerical results of the swelling ratio got lower than the experimental data, especially for the divergent die. This tendency is greatly different from the result of the K-BKZ model.
On the other hand, the uniaxial elongational property is important for the divergent die and the convergent one.
Ftrstly, the tendency of the K-BKZ model that the convergent die causes a larger swell in comparison with the divergent die does not change by adjusting the uniaxial elongational behavior by [Beta].
For the reasons why the lower shear die resulted in composites with higher degrees of fibrillation than the case of higher shear dies, it was assumed that 1) the high shear rate at [Phi] 1.4 dies resulted in an undesirable rise in the temperature of the melt beyond the optimum for fibrillation, and 2) the divergent dies
might have helped the relaxation of fibrils already formed in the strand (25).