High-field dielectric properties of LDPE, PP and PS films under AC ramp electric field application

Abstract

Recent improving of the processing capability of computers, it is getting possible to obtain the band structures for various kinds of polymers, such as polyethylene(PE), polypropylene(PP), polystyrene(PS), and so on, from a quantum chemical calculation. This numeric simulation is expected not only understanding of complex conduction mechanism in polymer, but also giving the useful information to develop high performance insulation materials. However, in order to confirm its validity, it is necessary to compare it with experimental results with high reproducibility as much as possible. In this study, three kinds of polymers, that is, PE, PP, and PS are chosen to understand the conduction mechanisms under AC high field, especially, the relation between the high-field dielectric properties of polymers and its structural formula. The simultaneous observations of dissipation current waveform and the number of electroluminescence (EL) pulses for these polymers have carried out under an AC ramp electric field application for 10 s. Here, at least 8 films in each sample were used to confirm its reproducibility. From the results of observations, the electric field dependences of the number of EL and the harmonic of dissipation current waveform were investigated. The influence of polymer structure on dielectric property under AC high field was discussed from these analyses.