Uniaxial elongational viscosity, steady

In Fig. 19 the steady state uniaxial elongational viscosity, ng/3. Is conqiared with the steady state shear, n> as well as dynamic, n , end complex, n, viscosities. It Is evident that some strain hardening, evident In I.100 (LLDPE-10) Is systematically diluted by the Increasing amount of LPX-30. Thus, Series 1 behaves as a truly miscible system. By contrast, addition of LDPE (11.100) to LPX-30 (1.0) Is generating more a complex variation of properties. The strain hardening, already visible at lOX of LDPE, reaches Its maximum not at lOOX LDPE but rather at 50 50 composition. Note that at e 0.1 (s" ) the maximum strain at break for 11.50 Is ejj > eg 3.2. The blends behave as Immiscible. 

Therefore, the steady-state uniaxial elongation viscosity ]g(e) can be calculated from... 

Uniaxial extensional viscosity and shear viscosity 77+ as functions of time after inception of steady straining for lUPAC A low density polyethylene. The open symbols are elongational viscosities the solid and half-open symbols are shear viscosities. Adapted from Meissner (1972). 

Relaxation spectrum has been calculated from oscillatory measurements (Figure 1) whereas the nonlinear parameters of all models were identified on the steady uniaxial elongational data only (Figure 2). All model parameters for corresponding materials are summarized in Tables 1-2. The model predictions in comparison with experimental data (shear viscosity, first q/i, and second normal sttess coefficients, y/2, uniaxial extensional viscosity, qE,u) are depicted in Figures 2-5 for all materials. 

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