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Electrical Conductivity of Polymer Composites Filled with Carbon Black

Conducting polymer composites filled with carbon black (CB) exhibit a positive temperature coefficient (PTC) effect. It is desirable to develop these composites with a low resistivity at room temperature and with a high PTC intensity. We evaluated the dependence of the PTC properties of the composites on the type and crystallinity of the component polymers, and the content and particle size of CB. Among the crystalline polymers investigated, we found that high-density polyethylene (HDPE) has the lowest resistivity at room temperature and the highest resistivity after polymer melting. The higher the crystallinity of HDPE, the lower the resistivity of the composites. The resistivity of the composites decreased with increasing CB content. The smaller the CB particle size, the lower the resistivity of the composites. We developed composites with a low resistivity at room temperature and a high resistivity after polymer melting. The resistivities of the composite consisting of 45 wt% HDPE and 55 wt% CB were 0.17 Ω cm at room temperature and 930 Ω cm after polymer melting.