Abstract
The similar molecular structure but different geometries of the carbon nanotube (CNT) and graphene nanoribbon (GNR) create a genuine opportunity to assess the impact of nanofiller geometry (tube vs. ribbon) on the electromagnetic interference (EMI) shielding of polymer nanocomposites. In this regard, GNR and its parent CNT were melt mixed with a polyvinylidene fluoride (PVDF) matrix using a miniature melt mixer at various nanofiller loadings, i.e., 0.3, 0.5, 1.0 and 2.0 wt%, and then compression molded. Molecular simulations showed that CNT would have a better interaction with the PVDF matrix in any configuration. Rheological results validated that CNTs feature a far stronger network (mechanical interlocking) than GNRs. Despite lower powder conductivity and a comparable dispersion state, it was interestingly observed that CNT nanocomposites indicated a highly superior electrical conductivity and EMI shielding at higher nanofiller loadings. For instance, at 2.0 wt%, CNT/PVDF nanocomposites showed an electrical conductivity of 0.77 S·m−1 and an EMI shielding effectiveness of 11.60 dB, which are eight orders of magnitude and twofold higher than their GNR counterparts, respectively. This observation was attributed to their superior conductive network formation and the interlocking ability of the tubular nanostructure to the ribbon-like nanostructure, verified by molecular simulations and rheological assays.
Highlights
In recent years, major concerns have been raised over electromagnetic pollution due to the widespread use of electronics and telecommunication systems [1]
Comparison of graphene nanoribbon (GNR)/polyvinylidene fluoride (PVDF) and carbon nanotube (CNT)/PVDF systems shows that both α-PVDF and β-PVDF have a stronger interaction towards CNT
It was found that the binding energy of all the nanomaterial/PVDF systems is higher for configuration H than for configuration F
Summary
Major concerns have been raised over electromagnetic pollution due to the widespread use of electronics and telecommunication systems [1]. Du et al [12] compared the electrical properties of CNTs and GNPs in polyethylene nanocomposites and reported a much lower electrical percolation for the CNT systems They claimed that CNTs created a three-dimensional conductive network in the polymer matrix, while GNPs ended up with a two-dimensional conductive structure. It is well known that EMI shielding is a strong function of the conductive network, that is, at a fixed nanofiller loading, a CPN with a better conductive network indicates superior EMI shielding [19,20] In this regard, the similar molecular structures but distinct geometries of GNR and its parent CNT create a genuine opportunity to investigate the effect of nanofiller geometry (tube vs ribbon) on conductive network formation and EMI shielding. Besides the EMI shielding measurement, we employed molecular simulations, rheology, and electrical conductivity as direct or indirect evidence of conductive network formation in the developed nanocomposites
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