High-Temperature Electrically Conductive Polymer Composites with Single-Walled Carbon Nanotubes

Abstract

High-temperature composite materials comprising single-walled carbon nanotubes embedded in a polybenzimidazole (PBI) polymer matrix with a weight percentage of nanotubes from 1 to 5% were prepared and characterized. Film composite samples were prepared by flow-coating from dispersions of nanotubes in 2% PBI solution in N-methyl-2-pyrrolidone. The temperature dependences of electrical resistance of the composites were studied in the range from room temperature to 300°C in a high vacuum at a pressure less than 1 × 10–3 Pa. The first heating cycle to 300°C gave rise to an increase in room-temperature electrical resistance of the samples due to the desorption of oxygen from the nanotubes. For the composites containing 5 and 1% nanotubes, the change was about 1.4 and 500 times, respectively. This increase was reversible: when the samples were transferred to the ambient air, the electrical resistance relaxed to its initial value. The thermal stability of the composites was proved by the repeatability of the subsequent heating cycles and by thermogravimetric analysis.