Charging mechanism of fibrous PTFE films

Author

Hu, Zhongming ; von Seggern, H.

Author_Institution

Inst. of Mater. Sci., Darmstadt Univ. of Technol., Germany

fYear

2005

fDate

11-14 Sept. 2005

Firstpage

31

Lastpage

34

Abstract

Recently air-breakdown charging has gained increasing interest with respect to porous electrets for application in novel piezoelectric transducers. A strong discrepancy between porous (closed-porous) polypropylene (PP) and fibrous (open-porous) teflon PTFE has been recognized concerning the obtainable polarization and the related piezoelectric d₃₃ coefficients. The present study aims to clarify the reasons for the poor charge separation ability of fibrous materials when exposed to electrical breakdown in their air voids. It will be demonstrated that a breakdown-induced conductivity hinders the formation of a large internal polarization by mutual charge compensation and therewith accounts for the obtainable low piezoelectric d₃₃ coefficients in fibrous materials. It will be shown that this limitation can be overcome by utilizing a sandwich structure of two FEP charge blocking layers incorporating a fibrous PTFE film.

Keywords

electrets; electric breakdown; piezoelectricity; polymer films; air voids; air-breakdown charging; breakdown-induced conductivity; charge separation; electrical breakdown; fibrous materials; fibrous teflon polytetrafluoroethylene film; piezoelectric d₃₃ coefficients; piezoelectric transducers; polarization; porous electrets; porous polypropylene; sandwich structure; Conducting materials; Corona; Electrets; Electrodes; Materials science and technology; Piezoelectric films; Piezoelectric polarization; Solids; Thermal stability; Voltage;

fLanguage

English

Publisher

ieee

Conference_Titel

Electrets, 2005. ISE-12. 2005 12th International Symposium on

Print_ISBN

0-7803-9116-0

Type

conf

DOI

10.1109/ISE.2005.1612311

Filename

1612311