Positive temperature coefficient effect in multiwalled carbon nanotube/high-density polyethylene composites

Muldwalled carbon nanotube (MWNT)-filled high-density polyethylene (HDPE) composites were prepared by a solution-precipitation process, and the temperature dependence of electrical conductivity of the MWNT/HDPE composites was studied. An obvious positive temperature coefficient (PTC) effect was found in the MWNT/HDPE composites with a relatively low MWNT concentration. Compared with that of carbon black (CB)/HDPE composite, the negative temperature coefficient (NTC) effect of the MWNT/HDPE composite at temperature above the melting temperature of HDPE was much less obvious and could be further eliminated after 80 kGy gamma-ray irradiation. The mechanism of the PTC and NTC effects in MWNT/HDPE composites was discussed. (C) 2005 American Institute of Physics.