Effect of Uniaxial Pressures on the Resistance of High Density Polyethylene/Carbon Black Composites

The relationship between uniaxial pressures and resistance of high density polyethylene/carbon black (HDPE/CB) composites was studied. The results showed that there existed a critical pressure below which composite resistance decreased with the increase of pressure and above which resistance increased with the increase of pressure. Correspondingly, these behaviors were defined as negative and positive pressure coefficient of resistance in this work. There existed obvious electrical hysteresis during unloading procedures. Nonrecoverable resistance was found when pressures approached to zero. It was believed that the uniaxial pressures-resistance relations were involved in the reformation and destructure of conductive network under pressures. A simple piezoresistive model was proposed phenomenologically to explain the experimental results.