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

•PBI/MWCNT composite films were manufactured by a facile solution casting.•Composites with >0.3 wt% MWCNT exhibited excellent electric heating performance.•Rapid electric heating rate and excellent electric power efficiency were achieved.•Composite films were thermally stable up to ∼450 °C even in air atmosphere.•Composite films can be applied as high performance electric heating materials.

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.

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