NUMERICAL-SOLUTION PROBLEMS OF HIGHLY CONCENTRATED ROD-LIKE MACROMOLECULES

The structural phenomenological approach is used to describe the rheol ogical behavior of materials exhibiting super-abnormal viscosity, that may be attributed to the orientational anisotropy of the material pro perties. It is assumed that the external fields and boundary condition s prevent the uniform orientation of all macromolecules in an arbitrar y direction in the bulk of material, even though the concentration is above the critical one. A uniform orientation takes place only within the limits of local regions (domains) having unique directors. The dom ains are defined as super molecular formations rotating and elongating in the shear flow. The domain rotation is described using the Hinch a nd Leal models. Upon reaching the critical shear intensity the domains are deformed turning into a thin layer of unbound macromolecules alig ned with flux. This is found to be the reason for orientational anisot ropy and super-abnormal viscosity. The rheological equations developed are used to calculate numerically the flow of polymeric materials in the screw channels of the extruder.