High-field Conduction and Breakdown against Physical and Chemical Properties for Low Density Polyethylene Films

I. Effects of Film Density

Abstract

The authors prepared the low density polyethylene (LDPE) films with densities of 0.917-0.927g/cm³, and discussed their high-field conduction and electrical breakdown above room temperature. We discussed high-field conduction and electrical breakdown against film density. The high-field current of the specimen with a lower density was higher than that of the specimen with a higher density. In addition, the breakdown strength of the former is lower than that of the latter. The density dependence of impulse breakdown strength was lower than that of dc breakdown strength. The breakdown strength depends on the value of high-field current. The breakdown strength of the specimen with a higher current is relatively lower than that of the specimen with a lower current. In spite of the small difference in density, 0.01g/cm³, a big difference in dc breakdown strength, about 2MV/cm was observed. Our data showed the stronger density dependence of breakdown strength as compared with the previously reported data. Our experimental result also supported that the conduction pass in which high-field current flows mainly in forward in the amorphous region and that the breakdown of LDPE above room temperature was caused by an thermal breakdown process.