Correlation between morphology, rheological behavior, and electrical behavior of conductive cocontinuous LLDPE/EVA blends containing commercial graphene nanoplatelets

Abstract

In this work, co-continuous blends of linear low density polyethylene (LLDPE)/ Ethyl vinyl acetate (EVA) containing graphene (GN) have been studied. Although mass-produced GN grade prepared by mechanochemical exfoliation of graphite and a facile melt compounding technique were adopted, it was possible to lower the electrical percolation threshold significantly by controlling the localization of GN nanoplatelets in the blend and by applying an appropriate thermal annealing procedure. The electrical and rheological properties of the obtained nanocomposites were systematically investigated to get an insight on the composite morphology. During annealing, an alignment between time-dependent behaviors of viscoelastic moduli and electrical conductivity was observed. An increase of both quantities and a simultaneous coarsening of the blend's morphologies occurred during the first 30 minutes of annealing followed by a more stable behavior. This rise was attributed to the diffusion and flocculation of GN nanoplatelets and their migration to the interface. Furthermore, the electrical and rheological percolation threshold concentrations were evaluated using a scaling Power law. The electrical percolation threshold was reduced to 0.5 vol% upon thermal annealing and was close to the rheological percolation threshold. Finally, the viscoelastic response of the composites was well described by a two-phase model, indicating that the effect of the relaxation dynamics of the interfacial network does not depend on the blend's morphology, even though the latter affects the space arrangement of GN and consequently the strength of the formed network.

Ultra-Low Percolation Threshold Induced by Thermal Treatments in Co-Continuous Blend-Based PP/PS/MWCNTs Nanocomposites

“…The whole treatment took 1 h 10 min ( Figure 1 ). The starting temperature of the treatment (160 °C) was chosen to prevent the so-called annealing effect [ 11 , 14 , 29 , 30 , 31 , 49 ] which could involve the coarsening of blend morphology. The temperature of 135 °C at the end of the treatment corresponds to the highest onset temperature of crystallization, evaluated by the DSC analysis.…”

“…Conductive nanocomposites are obtained by dispersing electrically conductive nanoparticles (particles with at least one of their dimensions ranging from 1 to 100 nm) within a matrix. The most used nanoparticles to obtain electrically conductive polymers are carbon black (CB) [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], carbon nanotubes (CNTs) [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 24 , 25 , 26 , 27 , 28 ], and graphene [ 12 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Due to the advantages conductive thermoplastic composites present, significant research has been conducted towards achieving certain desired properties at low filler concentrations, primarily by reducing the percolation threshold (PT).…”

“…Furthermore, other researchers suggested that the thermal annealing of polymer/filler or PB/filler composites above the melting or softening temperature could further decrease the PT and improve the electrical conductivity of a system [ 11 , 14 , 18 , 29 , 30 , 31 , 35 , 42 , 48 , 49 , 50 , 51 , 52 ]. In polymer blend-based composites, this effect is usually accompanied by changes in the blend morphology.…”

A Review on Graphene’s Light Stabilizing Effects for Reduced Photodegradation of Polymers

“…Recently, graphene, which consists of sp 2 -hybridized networks of carbon atoms in two dimensional hexagonal structures with one atom thickness, started gaining interest as a novel multifunctional additive that may effectively replace conventional light stabilizers, which are mostly specific in their action [13,14]. In addition to its excellent photostabilizing properties, which will be discussed in details in this article, graphene features promising electrical, mechanical, thermal, and chemical properties [15][16][17][18] attracting worldwide attention in the academic and industrial fields as a promising candidate for various applications [19][20][21][22]. Furthermore, the recent progress in large-volume and cost-effective manufacturing of few-layer graphene has made it an economically viable choice for the plastics industry.…”

Development of Reinforced Polyester/Graphene Nanocomposite Showing Tailored Electrical Conductivity

“…To date, a significant amount of research has been conducted on the area of matrix modification by GNP, with remarkable outcomes. For instance, GNP-filled polymers showed improved mechanical [6], electrical [7], gas barrier [8] and heat conduction [9] properties. Moreover, recent studies on the gene toxicity of GNP have concluded that graphene is much safer than carbon black for large-scale use [10].…”