TY  - JOUR
A1  - Wang, Jingwen
A1  - Rychkov, Dmitry
A1  - Nguyen, Quyet Doan
A1  - Gerhard, Reimund
T1  - The influence of orthophosphoric-acid surface modification on charge-storage enhancement in polypropylene electrets
T2  - Journal of applied physics
N2  - Bipolar electrets from polypropylene (PP) are essential, e.g., in electret air filters and in cellular-foam ferroelectrets. Therefore, the mechanism of surface-charge stability enhancement on PP electrets via orthophosphoric-acid surface treatment is investigated in detail. It is shown that the significant charge-stability enhancement can be mainly attributed to deeper surface traps originating from deposited chemicals and topographic features on the modified surfaces. Thermally stimulated discharge of chemically treated and non-treated PP films with different surface-charge densities is used to test the limits of the newly formed deep traps in terms of the capacity for hosting surface charges. When the initial surface-charge density is very high, more charges are forced into shallower original traps on the surface or in the bulk of the treated PP samples, reducing the effect of the deeper surface traps brought by the surface modification. The well-known crossover phenomenon (of the surface-charge decay curves) has been observed between modified PP electrets charged to +/- 2kV and to +/- 3kV. Acoustically probed charge distributions in the thickness direction of PP electrets at different stages of thermal discharging indicate that the deep surface trapping sites may have preference for negative charges, resulting in the observed asymmetric charge stability of the modified PP films.
Y1  - 2020
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/57685
SN  - 0021-8979
SN  - 1089-7550
VL  - 128
IS  - 3
PB  - American Institute of Physics
CY  - Melville
ER  -