Effects of carbon fiber content and size on electric conductive properties of reinforced high density polyethylene composites

The influence of the content and length-diameter ratio (l(f)/d(f)) of carbon fiber (CF) on the electric conductive behavior of the reinforced high density polyethylene (HDPE) composites was investigated. It was found that both the HDPE composites filled with CF with largel(f)/d(f) (short-cut) and the HDPE composites filled with CF with small l(f)/d(f) (triturated) presented obvious conductive percolation behavior; the percolation threshold value of the HDPE/short-cut CF composites was about 7.5 vol%, but when the triturated CF volume fraction was 18%, the percolation threshold value of the HDPE/triturated CF composite was obvious higher than that of the HDPE/short-cut CF composites. The positive temperature coefficient (PTC) transition temperature of the composites moved from low temperature to high temperature direction. For the same PTC transition temperature, the triturated CF weight fraction needed was at least two times higher than that of the short-cut CF. (C) 2017 Elsevier Ltd. All rights reserved.