The Preparation Of Carbon/Polymer Composite And Its Properties

Graphite nanoplatelets (GNPs) have been widely used in conductive polymer composites due to their large aspect ratio and extraordinary electrical property. In this paper, two kinds of polymers, silicon rubber and epoxy resin, were used to perpare electrical conductive composites. First, GNPs were prepared by ultrasonication of expanded graphite, then silicon rubber/GNPs/carbon nanotubes (CNTs) composites and epoxy/GNPs/nanoCaCO3 composies were prepared via liquid mixing method individually. The morphology and microstructure of the fillers and the composites were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The volume electrical resistivities of the composites were measured by a two-probe method. The conductive mechanism and the effect of the weight ratio of different geometry fillers on the electrical property were investigated in detail, and the mechanism of the synergistic effect in different geometry fillers was also proposed. The fracture toughness of epoxy/GNPs/CaC03 composies were measured by a three point bending method, meanwhile, the toughening mechanism of CaCO3 in epoxy resin was studied in detail. A series epoxy/GNPs composites were chosen to prepare activated carbon, the morphology and microstructure of the samples were examined by SEM and transition electron microscopy (TEM), and the electrochemical properties were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).Silicon rubber/GNPs composites were prepared by liquid mixing method, the percolation threshold of the composite was 3 wt.%. Fixing the total filler content at 1wt.%, the electrical conductivity of composites was remarkably improved by the addtion of CNTs. When the ratio of CNTs to GNPs was 3:7, the conductivity of the composite was the highest, almost two orders of magnitude higher than silicon rubber/GNPs composites. Due to the synergistic effect between the two different geometry fillers, the electrical conductivity of the composites with two kinds of fillers was higher than which only contained one kind filler.Epoxy/GNPs composites were prepared, the composites with a very low content of GNPs has good electrical conductivity. Fixing the total filler content at 2 wt.%, EG and CaC03 with different ratios were sonicated to obtain hybrid fillers with GNPs and CaCO3, and then epoxy/GNPs/CaCO3 composites were prepared via liquid mixing method. With the increase of CaCO3, the electrical conductivity is increased under the ratio of 1:9 (CaCO3 to GNPs), and after that, the conductivity declined rapidly. The synergistic effect between GNPs and CaCO3 promoted their individual dispersion, but too much electrically inert CaCO3 destroyed the conductive network. The fracture toughness of the composites was increased with the increase of CaC03, that's because CaCO3 shows the advantage of improving fracture toughness, when the composites containing only CaCO3, the fracture toughness of the composite was 2.7 MN-m-3/2.Activated carbons were synthesized from the carbonization and activation of a series of epoxy/GNPs composites. A conductive network was formed with the increase of GNPs. All the three activated carbons have good capacitance retentions, that's due to the high electrical conductivity of activated carbons.