Thermal Control Performances of Carbon Black/Tetradecanol-Based PTC Composites with Low Curie Temperatures
Self-regulating thermistors composed of conductive polymer composites exhibiting positive temperature coefficients(PTC)could replace resistors in heating devices and provide significant advantages in the active temperature control of electronic devices.However,the Curie temperatures(>60℃)of existing PTC composites are generally high,limiting their applications in the temperature control for electronic devices operating at room temperature.This study prepared PTC composites with a low Curie temperature(35℃)by the melt blending and molding methods.Tetradecanol with a low phase transition temperature was used as the phase transition matrix,carbon black(CB)was used as the conductive particles,and ethylene vinyl acetate copolymer(EVA)was used as the backbone.The effects of CB mass fractions on the electrical and PTC properties of the composites were investigated.The results indicate that the composite with a CB mass fraction of 12%exhibits a room temperature electrical resistivity of 0.5 Ω·m,a PTC strength of 7.0,and the negative temperature coefficient(NTC)effect is not observed.The microstructures of the composites were analyzed using scanning electron microscopy.The changes in electrical properties were correlated with the microstructures,explaining the intrinsic mechanisms behind the composite excellent PTC properties.Additionally,the thermal control behaviors of the PTC composites were investigated.The results indicate that,compared with the ordinary resistance heaters,the PTC composites possess a self-adaptive temperature control capability.The temperature of the controlled device could be maintained within the room temperature range and kept in equilibrium without an external control system.
Positive Temperature Coefficient CompositeCurie TemperatureRoom Temperature Electrical ResistivityPositive Temperature Coefficient PerformanceSelf-adaptive Temperature Control CapabilityEthylene Vinyl Acetate Copolymer
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