Carbon Mesophase / Carbon Nanotubes Nanocomposite - Functional Filler for Conductive Pastes

Abstract

This paper presents the characterization of carbonic functional phase based on carbon mesophase/carbon nanotubes nanocomposites used as functional filler in a polymeric matrix by optical microscopy, X-ray diffraction and functional by electrical resistivity measurements. The nanocomposites were prepared by adding of single walled carbon nanotubes (SWNT) or multi walled carbon nanotubes (MWNT) in a petroleum pitch. It was reported that SWNT behaves as either a metal or a semiconductor depending on the wrapping angle of the graphene sheet and its diameter, while MWNTs are always conductive. Carbonic functional phase was obtained by heat treatment of pitch/nanotubes mixtures at 450oC and 900oC temperatures. Polymeric composites were obtained by adding carbonic functional phase in an epoxy resin matrix. The polymeric composites were functional characterized from electrical point of view, establishing their behaviour. The electrical behaviour of the (SWNT/MWNT)/PP systems heat treated at 450�C is not largely influenced by the CNTs, because they are not creating any conducting connections. The composite systems, heat treated at 450�C, show a high resistivity of 105 ohm�cm, while the systems heat treated at 900�C show a lower electrical resistivity of 10-1 ohm�cm.

Electromagnetic properties of Si–C–N based ceramics and composites

“…When ceramics have insulating components (SiO 2 , BN, Si 3 N 4 and Al 2 O 3 ), which are usually EM transparent materials, with the inclusion of a conducting phase such as graphite, CNT, ordered mesoporous carbon (OMC) and graphene, they are promising for blocking EM radiation and reducing or eliminating EMI. 115,147 Their conductivity and dielectric property can be adjusted and controlled easily through chemical processing.…”

“…It means that carbon/ ceramic composites are suitable for EMI shielding. 115 The capability that a material shields EM wave can be expressed by EMI shielding effectiveness or efficiency (SE), indicating how much incident signal is blocked by the shielding material. A SE of 20 dB means that 99% incident signal is blocked, which is required for the commercial applications.…”