Studies of polymer electrets. II. Factors governing the stabilities of homoelectrets obtained from polystyrene and its derivatives

Abstract

SynopsisPolystyrene and its various alkyl and halo derivatives have been studied as homoelectrets and their stabilities under different environmental conditions determined. The stabilities of the homoelectrets prepared from these polymers depended on their volume resistivities, glass transition temperatures, and interactions with electron-acceptor impurities. Excellent stabilities were exhibited by the homoelectrets prepared from polystyrene, poly(vinyltoluene), poly(chlorostyrene), and poly(t-butylstyrene). It is postulated that the charged particles are trapped by the 7r-orbitals of the phenyl rings present in these polymers and that they are adversely affected by the presence of electron-acceptor compounds that generally form charge-transfer complexes with the phenyl groups.

Influence of physical aging on the performance of corona‐charged amorphous polymer electrets

“…The charge storage capability of a polymer electret material is mainly determined by the chemical nature of the polymer. In addition, additives and impurities can act either as trap sites or charge carriers depending on their nature and concentration 3–6. In semicrystalline polyolefines, the lamellar‐crystals embedded in the amorphous matrix form a heterogeneous morphology, where charge trapping and transport mechanisms depend for instance on the degree of crystallinity.…”

“…In amorphous polymers charge trapping occurs in particular sites of the polymer backbone, for instance at dipoles formed by electronegative atoms and groups, or in between interacting segments of adjacent polymer chains 5, 10–12. Several amorphous polymers have been reported to be good electret materials.…”

Tailored Additives to Improve the Electret Performance of Polycarbonates

“…[10,[15][16][17][18][34][35][36] The degree of improvement strongly depends on chemical structure and concentration of the additive with respect to the nature of the polymer.…”

“…In amorphous polymers charge trapping occurs at particular sites of the polymer backbone, for instance at electronegative atoms, or between interacting polymer chain segments. [10][11][12][13] Besides the chemical structure, catalyst residues, concentration and type of additives, processing conditions and thermal history have a great impact on the charge storage capability of a particular polymer material, especially for commercial grades. As will be investigated in this paper, these parameters can change the electret performance considerably; and, vice versa, knowledge of these relationships can be exploited to optimize polymer electret materials.…”

“…[10,14,15] For instance, in the case of poly-(propylene), anti-static additives act as charge carriers and lead to accelerated charge drain-off, whereas certain bisand trisamide additives act as charge traps and improve the charge storage capability distinctly. [16][17][18] However, the function as a charge trap additive strongly depends on the nature of a polymer and additives have to be tailored with respect to the polymer matrix.…”