Scanning electron microscope picture of a ferroelectretic foam, together with a graphical representation of the charging states in the pores.
A research team in Austria has been unravelling the secrets of the charging of plastic foams. Its findings open the way for the development of flat microphones and loudspeakers, as well as "smart" surfaces that could be used as floor coverings, among other things. The interest in the success of the group´s work - which was co-funded by the Austrian Science Fund (FWF) - has resulted in the integration of the project in a European interdisciplinary research network.
During a thunder storm the electrical tension between the earth and the air is discharged by the lightning and hence lowered. In non-polar polymer foams a comparable process results in the precise opposite - an increase in the electrical charge. First, an electric discharge is induced in the microscopic voids (pores) in foamed plastics by applying an external voltage. The propagation of the discharge is then inhibited by the insulating properties of the polymer foam, resulting in charging of the pore walls. As the non-polar material is non-conductive, the charge is stored there. A team under Prof. Siegfried Bauer at the Johannes Kepler University Linz Institute for Experimental Physics has succeeded in proving the existence of this phenomenon. In so doing it has challenged established scientific doctrine which holds that such states can only exist in polar materials.
Pores with potential
Univ.-Prof. Dr. Siegfried Bauer | alfa
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