Relationship between the Rheological and Molecular Structural Characteristics of Polypropylene

The results of studying the viscoelastic properties of polypropylene with various melt flow and ethylene unit content are presented. Using rheological measurements in the oscillation regime the data required for the analysis of relationship between the molecular weight characteristics and viscoelastic properties of various polypropylene brands are collected; the time–temperature superposition principle is applied for their processing. The values of the storage modulus and the loss modulus are compared with the MW values measured by GPC for a number of homopolymers and random and block propylene–ethylene copolymers; as result, the relationship between the rheological curves and the MW values is revealed. The results of this study are intended for assembling polymer MW database; in the future, this may contribute to the development of a rapid and accurate method to determine the molecular structure of polymers from rheological measurements.