5. Conclusion

In the study of structure development in semi-crystalline polymers, two approaches, by no means mutually exclusive, can be adopted:

• a descriptive approach, which, in the most general case, seeks to establish correlations between the molecular architecture of the polymer, its formulation, the forming conditions in a given process, the resulting microstructures and the final properties of the manufactured products. As suggested by the examples given, many studies are in fact limited to considering the influence of forming conditions on structures and properties, for one or more selected materials (polymers and formulation). For given forming conditions, some studies examine the influence of molecular structure on the development of structures (in this article, the case of LLDPE studied in sheath blowing).

• a...