Excellent positive temperature coefficient behavior and electrical reproducibility of HDPE/(TiC-CB) composites

The high-density polyethylene/(titanium carbide--carbon black) (HDPE/(TiC-CB) composites were prepared by melting blend process. Microstructure, room temperature resistivity, positive temperature coefficient (PTC) behavior and electrical reproducibility of composites were investigated. Results show that adding 3.0 vol% CB was in favor of reducing the room temperature resistivity of HDPE/(TiC-CB) composites, and leading to obtain high PTC intensity (the ratio of maximum resistivity to room temperature resistivity is defined as the PTC intensity). When the content of conductive fillers TiC was 32.0 vol% and CB was 3.0 vol%, the room temperature resistivity of composites was 0.8 Ω.m and PTC intensity reached 7.0, which is similar to the composites with 45.0 vol% TiC individually. The reduction of the inorganic material TiC facilitates the more flexibility of the composites, and the effect of PTC was still stability after several heating cycles. When the content of CB was more than 5.0 vol%, the room temperature resistivity was slightly reduced. However, the PTC intensity dropped below 3.7 abruptly. The micrographs of scanning electron microscopy (SEM) indicated that the CB had greatly influence on the formation of the electric conduction channel in the matrix.