Electrical conduction characteristics of VLDPE and LLDPE degraded by the voltage-thermal stress

The effects of voltage-thermal stress on the conduction behaviors of VLDPE and LLDPE have been investigated. It is observed that the conduction current density of the voltage-thermal aged VLDPE decreases while the conduction current of aged LLDPE increases significantly. We could conclude that the decrease of conduction current in the aged VLDPE may be attributed to the slight increase of activation energy and decrease of hopping distance, and the large decrease of activation energy (/spl sim/0.2 [eV]) together with electrode effect were responsible for the increase of conduction current in the aged LLDPE. We could confirm, from the XRD analysis, that the changes of conduction behaviors in aged VLDPE and LLDPE may be due to the decrease of deep traps or defects in the ordered phase of aged LLDPE and increase of traps between crystalline-amorphous boundaries of VLDPE respectively.