PTC/NTC Behaviors of Nanostructured Carbon Black-filled HDPE Polymer Composites

In this study, the effects of carbon black (CB) content and anodic oxidation treatment with AgNO3 on positive temperature coefficient (PTC) behavior of CB/HDPE nanocomposites were investigated. Also, the addition of elastomer as a toughing agent was studied. The 20~50 wt % of CB, 0~5 wt % of elastomer, and 1 wt % of AgNO3-filled HDPE nanocomposites were prepared using the internal mixer in 60 rpm at 160oC and the compression-molded at 180oC for 10 min. As a result, the room temperature resistivity and PTC intensity of the composites were dependent, to a large extent, on the content of CB, addition of elastomer, and surface chemical properties that were controlled in the relative arrangements of the carbon black aggregates in a polymeric matrix. Moreover, the composites with relatively low room temperature resistivity and suitable PTC intensity could be achieved by treatment of AgNO3. Consequently, it was noted that PTC effect was due to the deagglomeration or the breakage of the conductive networks caused by thermal expansion or crystalline melting of the polymeric matrix