Preparation and Performance of Modified Positive Temperature Coefficient Conductive Polymer Composites From Recycled High‐Density Polyethylene

ABSTRACT This study investigates the properties of conductive composites made from recycled high‐density polyethylene (rHDPE) sourced from urban plastic pollution, blended with virgin high‐density polyethylene (vHDPE) and carbon black (CB). The composites' room‐temperature resistivity, positive temperature coefficient (PTC) intensity, PTC behavior, and cyclic stability were evaluated. A control sample consisted of 100% vHDPE and CB, while rHDPE was incrementally substituted for vHDPE in 5% steps. Crosslinking with dicumyl peroxide (DCP) was used to optimize composite performance. Results showed that increasing rHDPE content raised the room‐temperature resistivity and PTC intensity but weakened cyclic stability and introduced a negative temperature coefficient (NTC) effect. However, adding DCP significantly improved room‐temperature resistivity and PTC intensity, eliminated the NTC effect, and enhanced cyclic stability. The optimal DCP content was found to be 0.2 wt% for the 10% rHDPE composite.