Improvement on Temperature-Sensing Property of Low-Density Polyethylene Based PTC Composites with Static Magnetic Field Treatment

Abstract

A stable magnetic field was applied during hot press molding of low-density polyethylene (LDPE)/carbon black (CB)/ carbon nanotube (CNT) composites and HDPE/CB/nickel powder composites. The effect of magnetic field treatment on the temperature-sensing property of LDPE-based positive temperature coefficient (PTC) composites was investigated. Experimental results indicate that the magnetic field treatment can lead to an alignment of CNT and nickel powder in LDPE along the direction of the applied external magnetic field. The alignment of these filler particles can endow the composites with low room-temperature resistivity and high PTC intensity when the concentration of CB is decreased. The alignment also can significantly improve mechanical property and processability of the composites. Compared with CNT, nickel powder with strong magnetism has more sensitive response to external magnetic field and is much easier to align in LDPE. Addition of nickel powder is beneficial for developing PTC composites with excellent comprehensive properties.