Impact of MW-CNT/polymer composites matrix type on the electrical and gas-sensitive properties

In this paper, polyurethane/MW-CNT, silicone/MW-CNT, and epoxy/MW-CNT nanocomposites were prepared, and their electrical and gas-sensitive properties were investigated. The aerosol-assisted chemical vapor deposition method was used to synthesize MW-CNTs from acetonitrile as a carbon source. These nanocomposites were prepared by an irreversible dispersion method that was developed by our group. SEM analysis results proved that smooth-surfaced, less defective MW-CNTs with 30–60 nm diameter and 60-50 μm length were synthesized successfully. The electrical conductivity of the prepared nanocomposites reveals the correspondence between the degree of uniformity of distribution of MW-CNTs inside polymers and the electrical conductivity of nanocomposites. The electrical conductivity graphs for Epoxy/x MW-CNTs and PU/x MW-CNTs nanocomposites have the same shape, and there is a sharp increase in electrical conductivity from 4% of MW-CNTs, but the values are different: Epoxy/x MW-CNTs (x = 8%) (1000 S/m) and PU/x MW-CNTs (x = 8%) (24.39 S/m). The electrical conductivity graph of silicone/x MW-CNT has a different shape, and percolation began at 2% of MW-CNT and increased sharply till 4%, then there was observed saturation. These results proved that the nanocomposite’s electrical conductivity properties depend on the polymer matrix nature. Simultaneously, the gas-sensitive properties of these nanocomposites were discovered. Thus, it was determined that the highest resistance change was observed for PVAc/x MW-CNT (x = 4%) nanocomposite under CO gas. Except for PVAl/x-MW-CNT (x = 4%), other nanocomposites show a gas-sensitive effect depending on gas types. Moreover, the resistance of all nanocomposites decreases with increasing temperature (from 20 to 120°C) and their behavior as semiconductors. However, the shapes of the graphs of the resistance depending on temperature are different depending on the nanocomposites, and their values are also different, some of them in the Om, KOm, and MOm ranges.