Low percolation threshold and balanced electrical and mechanical performances in polypropylene/carbon black composites with a continuous segregated structure

A novel continuous segregated structure was constructed in polypropylene (PP)/carbon black (CB) composites, to improve the electrical conductive performance and achieve a balance of the electrical conductivity and mechanical properties. Compared with traditional segregated structures reported in literature, PP matrix maintained a continuous structure instead of being separated completely by the electrical conductive fillers and CB particles formed a thorough conductive network in the continuous segregated PP/CB composites. A percolation threshold as low as 0.37 vol%, which is significantly lower than the percolation threshold of melt compounded PP/CB composites (2.75 vol%) and PP/polystyrene (PS)/CB composites (3.23 vol%) with a double percolation structure, was obtained because of the formation of the two-dimensional conductive network of CB particles. The mechanical performance tests showed that the tensile modulus, strength and elongation of break could be maintained well at CB contents around the percolation threshold. That is, with this novel continuous segregated structure, a balance of strength, toughness and electrical conductivity property can be achieved in conductive polymer composites. (C) 2016 Elsevier Ltd. All rights reserved.