Investigation of microstructure and electric heating behavior of hybrid polymer composite films based on thermally stable polybenzimidazole and multiwalled carbon nanotube

Abstract

Thermally stable polybenzimidazole (PBI)-based composite films filled with different pristine multiwalled carbon nanotube (MWCNT) contents of 0.0–10.0 wt% were manufactured by a facile solution casting, and their microstructural features, thermal and electrical properties were investigated as a function of the MWCNT content. Electron microscopic images and FT-IR spectra of the composite films confirmed that each MWCNT was wrapped with PBI chains by π–π interaction and thus they were well dispersed in the PBI matrix. Thus, the electrical resistivity of the composite films decreased considerably from ∼107 Ω cm to ∼10−1 Ω cm with the increment of the MWCNT content, especially at a certain percolation threshold of ∼0.25 wt% MWCNT. The composite films containing above 0.3 wt% MWCNT contents exhibited excellent electric heating performance. For instance, the composite film with 10.0 wt% MWCNT exhibited low temperature growth/decay time constant of ∼1 s, stable maximum temperatures of 40–220 °C, and high electric power efficiency of ∼7.32 mW/°C under the relatively low applied voltages of 5–25 V. Thermogravimetric analysis revealed that the composite films were thermally stable up to ∼450 °C under air environment. It is thus reasonable to contend that PBI/MWCNT composite films can be used as high performance electric heating materials in emerging application areas.