Effect of conjugated bonds on the charging of insulating polymers

Abstract

Different densities of conjugated bonds, which affect the polarization states necessary in forming polarons, are generated by stretching polymers at various rates. An investigation of the charging of the stretched high-impact polystyrene and high-density polyethylene by using a scanning electron microscope technique is made. The experimental results reveal that polymer charging is related to electron trapping as polarons at the polarized sites of the polymeric chains, confirming the recent interpretation of charging behavior in insulating materials.

A time-resolved current method for the investigation of charging ability of insulators under electron beam irradiation

“…Electron trapping, leading to the formation of space charges in insulators such as ceramics, 1-6 glasses, 2 and polymers [7][8][9][10][11][12] under nonpenetrating electron beam irradiation, has been observed for a long time and has attracted much interest because it is strongly related to the properties of a material such as complex permittivities ͑⑀Ј,⑀Љ͒, defects, and mobility. 4,5,9,13,14 The study of this phenomenon is an important means of understanding the dielectric strength and flashover phenomenon of insulators.…”

“…4,5,9,13,14 The study of this phenomenon is an important means of understanding the dielectric strength and flashover phenomenon of insulators.…”

Charging of deformed semicrystalline polymers observed with a scanning electron microscope

“…This can lead to the breakage of the chains in the amorphous phase (Fig. 8 c) and the formation of conjugated double bonds [12]. The present authors [12] have recently investigated the effect of conjugated bonds on charging and found that the formation of conjugated bonds leads to a decrease in the charging response of a polymer.…”

“…It should be noted that the polaron model has been employed also in the interpretation of another phenomenon, charge transport in molecularly doped polymers [7]. Despite the previous explanation of charging in polymers using the polaron concept [12], further confirmation and a more detailed description of the polaron concept in charge trapping is needed. One of our aims is to see whether the polaron concept can be employed in the interpretation of the charging behavior of deformed polymers.…”

“…For glasses and polymers, the cause of charging was less clear and it was uncertain whether the explanations for the insulating crystals were applicable [5]. Using the polaron model, we have interpreted the effect of conjugated bonds on charging for polystyrene (PS) and high-density polyethylene (HDPE) [12]. It should be noted that the polaron model has been employed also in the interpretation of another phenomenon, charge transport in molecularly doped polymers [7].…”