Van Gurp-Palmen-plot: a way to characterize polydispersity of linear polymers

Abstract

This article is concerned with the so-called van Gurp-Palmen-plot which charts the phase angles vs the absolute values of the complex shear modulus from a rheological experiment. Its basic characteristic features are elucidated for polymers having a simple, i.e., a linear structure. A subsequent manuscript will then address more complicated topologies as present in long chain branched polymers.

A unique type of curve is typical for linear samples. This type of curve is characterized by one minimum and one inflection point. The locations of these points and thus the shape of the curve are correlated to the plateau modulus, to the molecular weight, and, especially, to the polydispersity. With these findings in mind, scaling is then introduced to the van Gurp-Palmen-plot. Finally, bimodal homopolymer blends are considered in order to learn how two distinct relaxation processes influence the shape of the van Gurp-Palmen-plot.