The influence of mold pressing parameters on PTC of HDPE/CB composites

The influence of mold pressing parameters on the positive temperature coefficient of high-density polyethylenel carbon black composites was investigated. The composites with a low resistivity at room temperature and a high positive temperature coefficient can be obtainee with the mold pressing parameters as follows: mold pressing pressure 6–14MPa, mold pressing temperature 150–170°C, mold pressing time about 15 min, and room temperature of molded specimen after cooding for 20–60 minutes. The positive temperature coefficient effect of the composite is 7.7 when it is prepared under the mold pressing parameters, and the negative temperature coefficient effect is less than 0.8. Scanning electron microscopy (SEM) reveals some aggregations of carbon black particles with a size of 1 μm inside the composite, which was obtained at the mold pressing temperature of 180°C.