Preparation and application practice of temperature self-regulating flexible polymer electric heaters

The present article considers a comparative analysis of two elastomers, polyurethane (PUC) and organosilicon (OSC), both modified with 1.0-9.0 wt.% multiwall carbon nanotubes (MWCNTs). The MWCNTs-1 and MWCNTs-2 were synthesized through CVD method using Co-Mo/Al2O3-MgO and Fe-Co/2,1Al2O3. The results obtained showed that the lowest bulk conductivity (5 x 10(-10) S x cm(-1)) was typical for PUC elastomer modified with 1 wt.% MWCNTs-2. As for OSC elastomer (modified with 9 wt.% MWCNTs-1), the lowest bulk conductivity was found to be 0.4 S x cm(-1). The maximum temperature field uniformity was established for OSC elastomer modified with 7 wt.% MWCNTs-2, whereas in the modified PUC-based elastomer, the nonuniform temperature field took place. This might be caused by local MWCNTs entanglement manifested in the formation of agglomerates or a denser packing of conductive networks. The best combination of the polymer matrix and MWCNTs type was revealed. Finally, it was established that for electric heaters, it is the most efficient to employ OSC modified with 7 wt.% MWCNTs and use MWCNTs-1 or MWCNTs-2, depending on the feeding voltage level of 12 or 24 V. This study is of special importance in household purposes, clothing with built-in heating panels, car/tractor systems, minibus interiors, onboard thermal ventilation systems, clothing, and aircraft industries.