The high-density polyethylene /carbon black (HDPE/CB) composite with a CB volume fraction of 0.113 is isothermally annealed at various temperatures from 116 to 149 degrees C, covering the positive temperature coefficient (PTC) transition and the negative temperature coefficient regions during heating as well as from 149 to 122 degrees C above the reverse-PTC transition during cooling. Influences of annealing temperature on the resistance-temp era tu re and the resistance-time characteristics are discussed. The results show that both the resistance-temperature and the resistance-time characteristics are highly sensitive to the thermal history. Effects of recrystallization of HDPE and redistribution of CB aggregates in HDPE on the performance are discussed. (c) 2007 Wiley Periodicals, Inc.