Influence of melt-mixing processing sequence on electrical conductivity of polyethylene/polypropylene blends filled with graphene

• Published in: Polymer bulletin (Berlin, Germany) Vol. 74; no. 4; pp. 1237 - 1252
• Main Authors: Tu, Ce, Nagata, Kenji, Yan, Shouke
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2017; Springer Nature B.V
• Subjects: Blending; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Composite materials; Compounding; Electrical resistivity; Graphene; Graphite; High density polyethylenes; Hydrochloric acid; Localization; Mechanical properties; Nitrogen; Organic Chemistry; Original Paper; Percolation; Physical Chemistry; Polyethylene; Polymer blends; Polymer Sciences; Polyolefins; Polypropylene; Potassium; Rheological properties; Rheology; Soft and Granular Matter; Sulfuric acid; Transmission electron microscopy; Japan; Polymer blend; Graphene; Selective localization; Electrical percolation threshold; Processing sequence
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-016-1774-4

In this paper, we produced composites of high-density polyethylene (PE)/polypropylene (PP) filled with graphene by melt compounding. Comparing composites produced in three processing sequences, we explored whether the sequence improved the composites’ electrical conductivity. The (graphene/PE)/PP composite, prepared by simultaneous compounding, exhibited an electrical percolation threshold of 1.25 vol.%. In contrast, the (graphene/PP)/PE composite, prepared by blending the graphene with PP first and then blending the graphene/PP with PE, had a much lower electrical percolation threshold at less than 0.83 vol.%. At its percolation threshold, the (graphene/PP)/PE composite had a conductivity about two orders of magnitude higher than the (graphene/PE)/PP composite. We attribute this difference in conductivity to differences in the graphene distributions in the composites. In the (graphene/PE)/PP composite, the graphene sheets were selectively dispersed in the PE phase; in the (graphene/PP)/PE composite, some of the graphene was localized at the interface of the PE/PP blend. We also showed how the different processing sequences affected the composites’ measured rheological and mechanical properties.