6. Conclusion

While the study of the linear viscoelastic behavior of molten polymers provides an additional tool for the analysis of polymer structure, the nonlinear viscoelastic behavior at large deformations in the molten state is more directly correlated to the material's processability. There is, of course, a strong link between structure, linear and non-linear rheological behavior and processing. Thus, only a global approach can achieve the expected optimization in terms of material and process suitability.

Over the past four decades, empirical knowledge of rheological behavior has evolved into numerical modeling tools that use experimental data in simple shear and elongation flows, at small and large strains, to predict phenomena in complex flow situations.

Non-linear behavior laws combining relative ease of numerical use and relevant behavioral...