Rheological Characterization of Long Chain Branching in a Melt of Evolving Molecular Architecture

Abstract

A rheological method was presented for estimating the degree of long chain branching of a polymer melt undergoing the early stages of a cross-link induced reactive modification. The model was tested on a series of polypropylenes, all produced from the same linear precursor in the presence of varied peroxide concentrations. It was found that the branching indices predicted from the analysis of zero shear viscosity of the samples were in good agreement with those evaluated by size exclusion chromatography combined with intrinsic viscosity measurements.