Enhanced Positive Temperature Coefficient Behavior of High‐Density Polyethylene/Carbon Black Composites via Waste Rubber Volume Exclusion and Electron‐Beam Irradiation Crosslinking

ABSTRACT

Positive temperature coefficient (PTC) conductive polymer composites are promising for self‐regulating heating and overcurrent protection, yet high‐density polyethylene (HDPE)/carbon black (CB) systems still struggle to combine low room‐temperature resistivity, high PTC intensity, and stable high‐temperature electrical response. Herein, ground tire rubber (GTR)‐induced volume exclusion and electron beam (EB) irradiation crosslinking were combined to regulate the conductive network of HDPE/CB composites. GTR particles acted as a stable dispersed phase in the HDPE matrix, compressing the effective distribution space of CB and facilitating conductive pathway formation. Increasing GTR content from 0 to 30 wt.% reduced the room‐temperature logρv from 1.08 to 0.38, although the PTC intensity decreased from 4.80 to 3.24 because of reduced crystallinity and weakened HDPE thermal expansion. After EB irradiation, the crosslinked network restricted HDPE chain motion and CB migration, eliminated the high‐temperature NTC effect, and increased the PTC intensities of GTR‐containing composites to 6.93, 5.97, 5.19, and 4.93. Their PTC‐intensity change rates after three thermal cycles decreased to 2.02%, 1.51%, 1.93%, and 4.67%, respectively. This work provides a low‐cost route for high‐value utilization of waste tire rubber in high‐performance PTC composites.