Electrical tree growing properties of LDPE influenced by heat treatments

Crystallization and inner stresses can influence electrical aging properties of insulating material. Heat treatment is one of the most important processes in production of insulating material. This paper presents the growing properties of electrical trees in low density polyethylene (LDPE). The LDPE specimens used for electrical tree experiments are obtained by four different heat treatment processes. These LDPE specimens have different crystallization and inner stresses. The pictures of electrical trees in the LDPE specimens are recorded by a long focal-length microscope system. The length of electrical trees is measured to study the influences of crystallization and inner stresses on the growing properties of LDPE. Melting enthalpy of these specimens is meanwhile measured by the differential scanning calorimetry (DSC) technique. Experiment and analysis results show that heat treatment processes influence the growing properties of electrical trees in LDPE.