Nonlinear “oddities” at the percolation of 3D hierarchical graphene polymer nanocomposites
Journal article, 2020

The nonlinear rheology of a novel 3D hierarchical graphene polymer nanocomposites was investigated in this study. Based on an isotactic polypropylene, the nanocomposites were prepared using simple melt mixing, which is an industrially relevant and scalable technique. The novel nanocomposites stand out as having an electrical percolation threshold (≈0.94 wt%) comparable to solution mixing graphene-based polymer nanocomposites. Their nonlinear flow behavior was investigated in oscillatory shear via Fourier-transform (FT) rheology and Chebyshev polynomial decomposition. It was shown that in addition to an increase in the magnitude of nonlinearities with filler concentration, the electrical percolation threshold corresponds to a unique nonlinear rheological signature. Thus, in dynamic strain sweep tests, the nonlinearities are dependent on the applied angular frequency, potentially detecting the emergence of a weakly connected network that is being disrupted by the flow. This is valid for both the third relative higher harmonic from Fourier-transform rheology, I3/1, as well as the third relative viscous, v3/1, Chebyshev coefficient. The angular frequency dependency comprised non-quadratic scaling in I3/1 with the applied strain amplitude and a sign change in v3/1. The development of the nonlinear signatures was monitored up to concentrations in the conductor region to reveal the influence of a more robust percolated network.

Nonlinear oscillatory shear

Hierachical graphene

Polymer nanocomposites

Percolation

Author

Roland Kádár

Chalmers, Industrial and Materials Science, Engineering Materials

Karolina Gaska

University of Bristol

Thomas Gkourmpis

Borealis AB

Chalmers, Industrial and Materials Science, Engineering Materials

Rheologica Acta

0035-4511 (ISSN)

Vol. 59 5 333-347

High performance and scalable tailored graphene - polyolefin nanocomposites

VINNOVA, 2018-11-30 -- 2021-02-28.

Subject Categories

Applied Mechanics

Textile, Rubber and Polymeric Materials

Composite Science and Engineering

Areas of Advance

Production

Materials Science

DOI

10.1007/s00397-020-01204-w

More information

Latest update

6/5/2020 7