Conductive polymer foams with carbon nanofillers – Modeling percolation behavior

Abstract

Abstract.A new numerical model considering nanofiller random distribution in a porous polymeric matrix was developed to predict electrical percolation behavior in systems incorporating 1D-carbon nanotubes (CNTs) and/or 2D-graphene nanoplatelets (GNPs). The numerical model applies to porous systems with closed-cell morphology. The percolation threshold was found to decrease with increasing porosity due to filler repositioning as a result of foaming. CNTs were more efficient in forming a percolative network than GNPs. High-aspect ratio (AR) and randomly oriented fillers were more prone to form a network. Reduced percolation values were determined for misaligned fillers as they connect better in a network compared to aligned ones. Hybrid CNT-GNP fillers show synergistic effects in forming electrically conductive networks by comparison with single fillers.

Electrical Conduction Behavior of High-Performance Microcellular Nanocomposites Made of Graphene Nanoplatelet-Filled Polysulfone

“…The increase in the values of electrical conductivity, by increasing the gas volume percentage, can be explained by the reduction in GnP interparticle distance as a result of a reduction in the characteristic dimension of the continuous phase in the cellular structure through a more desirable re-orientation of graphene nanoparticles. Similar results have been reported by O. Maxian et al [40], where their modeling of a percolation system, consisting of nanocomposites with carbon-based nanofillers, showed a decrease in terms of percolation threshold with increasing the porosity of nanocomposites. Gedler et al [41] also presented the results o electrical conductivity enhancement with increasing the expansion ratio, with an optimum limit to reach maximum efficiency in augmenting the electrical conductivity.…”

Enhancing the electrical conductivity of polyetherimide‐based foams by simultaneously increasing the porosity and graphene nanoplatelets dispersion

“…Said results can be explained by the further reduction of GnP interparticle distance as a consequence of a decrease in the characteristic dimension of the solid phase in the foams through a more favorable reorientation of GnP particles. A modeling study of percolation behavior of foams with carbon‐based nanofillers by O. Maxian et al showed that the percolation threshold tends to decrease with increasing the porosity due to the repositioning of the nanoparticles. Another work by G. Gedler et al showed that PC‐based foams with GnP as conductive nanoparticles could reach electrical conductivity values up to 10 −7 S/m with increasing the expansion ratio.…”

Effects of Carbon Nanotubes/Graphene Nanoplatelets Hybrid Systems on the Structure and Properties of Polyetherimide-Based Foams

“…Additionally, Wu et al [ 43 ] conducted a study using CNT and carbon black (CB) as hybrid fillers for a biodegradable polylactide composite, showing the synergic effect between both fillers in controlling cell size and forming an effective network, significantly enhancing the electrical conductivity of the foamed composites, especially when compared to similar foams containing only CNT. Maxian et al [ 23 ] also studied the combination of GnP and CNT using a new numerical model considering nanofiller random distribution in a porous polymeric matrix in order to predict the electrical percolation behavior of polymer-based composites. In their simulations, the hybrid system exhibited significantly lower percolation values in porous systems when compared to the prediction given by the rule of mixtures, demonstrating the synergic effects of combining CNT and GnP.…”

“…Therefore, a percolative conduction model was used, as the nanofiller content was enough to establish an electrical percolation network. The percolative model has been used extensively for polymeric composites containing CNT as a conductive nanofiller [ 23 , 43 , 44 , 45 , 46 , 47 , 48 ].…”

“…Various attempts to prepare hybrid CNT/graphene materials have been carried out to create transparent conductors [ 14 , 15 , 16 , 17 ], electrodes [ 18 ], electron field emitters [ 19 ], field effect transistors [ 17 ], supercapacitors [ 20 ], and Li-ion batteries [ 21 , 22 ]. Maxian et al [ 23 ] numerically investigated the electrical percolation behavior of porous systems incorporating carbon 1D- and 2D-fillers assuming perfect random filler distribution and realistically modeling ‘foaming’ by displacing the fillers. Their model was able to successfully capture experimental trends [ 24 ] showing the increased conductivity and lower percolation threshold of porous compared to non-porous systems.…”