2.2. Composite materials—characterization
Electrical conductivity of the composite films was studied using Van der Pauw 4-terminal method using an MCP-T610 and MCP-TPLSP probe (Low Rester, Mitsubishi Chemical Analytech Co., LTD). Raman spectroscopy was carried out using a NICOLET ALMEGA XR Dispersive Raman (Thermo Fisher Scientific K.K.) and combined with optical microscopy to assess the electronic structure and spatial distribution of SG-SWCNT in the composite (Fig. 1d). The crystallinity of the SG-SWCNT and the extent of its structural damage during the processing, were evaluated from the ratio of the Raman G- and D-bands of SG-SWCNT. For purpose of visualization of the SG-SWCNT inside the elastomer, methyl isobutyl ketone (MIBK) or N,N-dimethylformamide (DMF) was used to fully dissolve the elastomer from the composite film ( Fig. 1e). This reveals the structure of SG-SWCNT network inside the elastomeric matrices and provided an understanding into the origin of electrical conductivity.