Study on suppression mechanism of space charge accumulation in nano-doped LDPE

The introduction of nano-fillers into polyethylene can suppress space charge accumulation. The mechanism of this phenomenon hasn´t been understood clearly, and has been explained in two different ways, i.e. an interface behavior that reduces charge injection and a bulk property that affects charge migration. In order to investigate which factor determines the space charge behavior in LDPE nano-composites, samples of triple-layer structure are measured. The experimental results show that the nano-fillers can reduce charge injection. However, the reduced charge injection cannot entirely remove the space charge. The bulk property also plays an important role in space charge suppression. Furthermore, a bipolar blocking phenomenon is found in our triple layer sample at high temperature. This can be explained by a shift in the apparent Fermi (charge demarcation) level near the electrode due to the trapping of injected charge, which increases the interface barrier.