Enhanced Electrical and Electromagnetic Interference Shielding Properties of Polymer–Graphene Nanoplatelet Composites Fabricated via Supercritical-Fluid Treatment and Physical Foaming
| Autor: | Biao Zhao, Mahdi Hamidinejad, Tobin Filleter, Nima Moghimian, Chul B. Park, Azadeh Zandieh |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
chemistry.chemical_classification
Materials science Nanocomposite Composite number Percolation threshold 02 engineering and technology Dielectric Polymer Polyethylene 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences chemistry.chemical_compound chemistry Electromagnetic shielding General Materials Science High-density polyethylene Composite material 0210 nano-technology |
| Zdroj: | ACS Applied Materials & Interfaces. 10:30752-30761 |
| ISSN: | 1944-8252 1944-8244 |
| DOI: | 10.1021/acsami.8b10745 |
| Popis: | Lightweight high-density polyethylene (HDPE)-graphene nanoplatelet (GnP) composite foams were fabricated via a supercritical-fluid (SCF) treatment and physical foaming in an injection-molding process. We demonstrated that the introduction of a microcellular structure can substantially increase the electrical conductivity and can decrease the percolation threshold of the polymer-GnP composites. The nanocomposite foams had a significantly higher electrical conductivity, a higher dielectric constant, a higher electromagnetic interference (EMI) shielding effectiveness (SE), and a lower percolation threshold compared to their regular injection-molded counterparts. The SCF treatment and foaming exfoliated the GnPs in situ during the fabrication process. This process also changed the GnP's flow-induced arrangement by reducing the melt viscosity and cellular growth. Moreover, the generation of a cellular structure rearranged the GnPs to be mainly perpendicular to the radial direction of the bubble growth. This enhanced the GnP's interconnectivity and produced a unique GnP arrangement around the cells. Therefore, the through-plane conductivity increased up to a maximum of 9 orders of magnitude and the percolation threshold decreased by up to 62%. The lightweight injection-molded nanocomposite foams of 9.8 vol % GnP exhibited a real permittivity of ε' = 106.4, which was superior to that of their regular injection-molded (ε' = 6.2). A maximum K-band EMI SE of 31.6 dB was achieved in HDPE-19 vol % GnP composite foams, which was 45% higher than that of the solid counterpart. In addition, the physical foaming reduced the density of the HDPE-GnP foams by up to 26%. Therefore, the fabricated polymer-GnP nanocomposite foams in this study pointed toward the further development of lightweight and conductive polymer-GnP composites with tailored properties. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|