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Carbon nanotube (CNT) composites are ideal materials for electric heating (E-heating) components owing to their lightweight, rapid heating ability, and easy processability for microscale patterns. However, careful consideration of their thermal stability and the effect of E-heating on CNT composites is necessary to ensure safety and long-term durability. Thermal degradation of CNT composites as a result of E-heating was found to be much more severe than air convection heating (C-heating). Enhanced mechanical properties of CNT composite were observed after 40 h C-heating, while E-heating composites became fragile that the matrix was severely damaged at the same temperature/hours. Consequently, the electrical resistance of the CNT composite for E-heating was dramatically increased. To avoid thermal degradation and a dramatic increase in resistance, the E-heating temperature should be much lower than the temperature limit of thermally stable polymer. In addition, thermal degradation of the polymer matrix could be relieved through the addition of CNTs, which can be understood as parallel resistor model, by spreading thermal concentration throughout the polymer matrix. [ABSTRACT FROM AUTHOR]

Negative temperature coefficient of resistance of a material can be a disadvantage in high temperature applications, causing a system to be thermally unstable as the temperature increases. We investigate the concept of excluded volume to suppress the negative temperature coefficient of resistance of a multi-walled carbon nanotube/silicone rubber composite. When micro- or nano-silica particles are incorporated to realize the segregated conductive network, the resistance-temperature dependence of the composite is suppressed in both the conductive polymer composite itself and a fuser unit for printers having the carbon nanotube composite as heating layer. It is believed that the effect of mechanical reinforcement and suppression in thermal expansion by the secondary particles are essential for suppressing the temperature dependence of resistance. This investigation on the excluded volume can be interpreted to offer a new perspective on nanomaterial-based thermistor technology. [ABSTRACT FROM AUTHOR]