Electrical Properties of the Carbon-Nanotube Composites Film Under Extreme Temperature Condition

Carbon nanotube (CNT) composites have been widely investigated for electric heating applications (such as water heater, de-icing unit, and patternable micro heaters) owing to their rapid heating, flexibility and light-weight properties. For practical use of CNT composite as heating element applications, the change of resistance with varying temperature must be interpreted. In this study, electric heating behavior of CNT/Nylon 6 composite film (10 wt%) and CNT/Polydimethylsiloxane (PDMS) composite film (10 wt%) were evaluated by measuring the change in normalized resistance under extreme temperature from -50 °C to 100 °C. While CNT/PDMS composite film showed 25% normalized resistance change from -50 °C to 100 °C, in the case of CNT/Nylon 6 composite film, only 10% normalized resistance change was shown. The difference of resistance change is attributed to the difference of the polymer's coefficient of thermal expansion (CTE), which is a crucial factor to consider in the design of CNT composites as a heater or heating sensor. CNT/Nylon 6 composite film is appropriate for flexible heating unit and de-icing application, due to the lower degree of resistance change than that of CNT/PDMS composite film. In addition, a thermal cycling test was conducted to determine the thermal stability and repeatability of CNT composites.