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Polymers 2018, 10(2), 222;

Effects of Particle Size and Surface Chemistry on the Dispersion of Graphite Nanoplates in Polypropylene Composites

Institute for Polymers and Composites/I3N, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
Leibniz Institute for Polymer Research Dresden, Hohe Strasse 6, D-01069 Dresden, Germany
Authors to whom correspondence should be addressed.
Received: 8 December 2017 / Revised: 14 February 2018 / Accepted: 21 February 2018 / Published: 24 February 2018
(This article belongs to the Special Issue Polymer Nanocomposites)
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Carbon nanoparticles tend to form agglomerates with considerable cohesive strength, depending on particle morphology and chemistry, thus presenting different dispersion challenges. The present work studies the dispersion of three types of graphite nanoplates (GnP) with different flake sizes and bulk densities in a polypropylene melt, using a prototype extensional mixer under comparable hydrodynamic stresses. The nanoparticles were also chemically functionalized by covalent bonding polymer molecules to their surface, and the dispersion of the functionalized GnP was studied. The effects of stress relaxation on dispersion were also analyzed. Samples were removed along the mixer length, and characterized by microscopy and dielectric spectroscopy. A lower dispersion rate was observed for GnP with larger surface area and higher bulk density. Significant re-agglomeration was observed for all materials when the deformation rate was reduced. The polypropylene-functionalized GnP, characterized by increased compatibility with the polymer matrix, showed similar dispersion effects, albeit presenting slightly higher dispersion levels. All the composites exhibit dielectric behavior, however, the alternate current (AC) conductivity is systematically higher for the composites with larger flake GnP. View Full-Text
Keywords: graphite nanoplates; surface modification; polymer composites; dispersion graphite nanoplates; surface modification; polymer composites; dispersion

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Santos, R.M.; Mould, S.T.; Formánek, P.; Paiva, M.C.; Covas, J.A. Effects of Particle Size and Surface Chemistry on the Dispersion of Graphite Nanoplates in Polypropylene Composites. Polymers 2018, 10, 222.

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