Skip to content

Characterizing Long-chain Branching in Commercial HDPE Samples via Linear Viscoelasticity and Extensional Rheology

Abstract

It is well established that polymer chain architecture and the distribution of molecular weight play a key role in the flow behavior (processing) and performance of a given polymer material. Long-chain branching (LCB) in particular is known to strongly affect the processability and the material performance of polymers. Often branching is a result of the polymerization process and therefore must be quantified in every sample. We study four commercial high-density polyethylene (HDPE) samples with unknown degrees of polydispersity and LCB. We first use size-exclusion chromatography and linear shear rheology to identify differences in molecular weight, polydispersity, and LCB. Each material is then tested in constant rate and constant stress uniaxial extension using a filament stretching rheometer to quantify extensional viscosity and strain hardening. Correlations between nonlinear extensional rheology, LCB and polydispersity are discussed. We show that the combination of the van Gurp-Palmen plot and extensional rheology allows for a full characterization of the LCB fraction and their effect on extensional rheology.

Publication Metadata

Authors

Morelly, Samantha L.; Alvarez, Nicolas J.

Citation

Morelly, S.L., Alvarez, N.J. Characterizing long-chain branching in commercial HDPE samples via linear viscoelasticity and extensional rheology. Rheol Acta. 59, 797–807 (2020). DOI: https://doi.org/10.1007/s00397-020-01233-5