Enhanced positive temperature coefficient behavior of the high-density polyethylene composites with multi-dimensional carbon fillers and their use for temperature-sensing resistors

Positive temperature coefficient (PTC) materials usually suffer from the low intensity and poor reproducibility, which will limit their service time under harsh thermal control conditions. In this paper, both the functionalized carbon black (CB) and multi-walled carbon nanotubes (MWNT) were introduced into the high-density polyethylene (HDPE) matrix to achieve the improved PTC behaviors. The CB/ MWNT/HDPE and CB/HDPE composites were respectively prepared through solution-melt mixing method, and their PTC behaviors were investigated. The results show that the HDPE composites filled with the modified CB exhibit better PTC effect than those filled with raw CB due to the anti-oxidation action of coupling agent. Moreover, it was found that the addition of a small amount of MWNT (0.7 wt%) into the HDPE composites with CB (18 wt%) could make larger intensity (similar to 6.5) and better reproducibility of PTC behavior. The synergistic effect of the modified CB and MWNT on improving the service time of PTC effect was further explored. The use of multi-dimensional carbon fillers was expected to provide a new route to fabricate high-performance polymeric PTC materials with a potential application as flexible temperature-resistivity sensor.