Influence of low pressure on electrets behaviour at various air gaps

Viraneva, A.; Yovcheva, T.; Gencheva, E. A.; Mekishev, G.

doi:10.1016/j.jnoncrysol.2009.09.033

Cited by 7 publications

(7 citation statements)

References 9 publications

(19 reference statements)

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“…At lower pressures the surface potential is also constant but has different values for the different cases. A similar behavior has been observed and described earlier [9,10].  The pressure range in which the sharp surface potential decay occurs is narrow for polypropylene and poly(ethylene terephthalate) electrets and wide for poly(lactic acid) electrets;  The minimal value to which the surface potential decays at low pressures is higher for positively charged electrets than those for negatively charged ones, independently of the material type;  The minimal values of the surface potential at low pressures are the highest ones for the positively charged poly(lactic acid) electrets.…”

Section: Resultssupporting

confidence: 89%

“…However, only several papers refer to the influence of lowered pressure on electrets surface potential decay [4][5][6][7][8][9][10][11]. In the earliest papers [4][5][6] a dissectible capacitor was used to measure the surface charge density.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, air gaps between the charged surface and the measuring electrode were formed. In our investigations the method of the vibrating electrode with compensation was used to measure the electrets surface potential [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…In [10] we studied the influence of pressure on polypropylene samples placed into the vacuum chamber between two plate short-circuited electrodes at various air gap thicknesses.…”

Section: Introductionmentioning

confidence: 99%

“…Some authors assume that charge decay is a result of discharges occurring in air according to Paschen's law [4,6], and others believe that surface potential decay is due to ion desorption from electret surfaces [5,[7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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Pressure effect on the polymer electret films

Viraneva

Yovcheva

Mekishev

2013

IEEE Trans. Dielect. Electr. Insul.

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Polypropylene (PP), poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET) samples, charged in a positive or in a negative corona were studied. The charging of the samples in a corona discharge was carried out by means of a conventional corona triode system. After charging the surface potentials were measured using the method of the vibrating electrode with compensation and then the electrets were placed into a vacuum chamber under different low pressures from 10 Pa to 10 5 Pa for 30 minutes. The effect of lower pressure on the surface potential of charged samples was investigated. It was established that the reduced pressure led to the surface potential decay of the electrets. The results obtained of polypropylene, poly(ethylene terephthalate) and poly(lactic acid) electrets show that charge decay is different for different polarity of the corona voltage and for different materials. The same effect was earlier observed for other polymer films. Processes of desorption from the electrets surface accompanied with surface diffusion are supposed to occur.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In [10] we studied the influence of pressure on polypropylene samples placed into the vacuum chamber between two plate short-circuited electrodes at various air gap thicknesses.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pressure effect on the polymer electret films

Viraneva

Yovcheva

Mekishev

2013

IEEE Trans. Dielect. Electr. Insul.

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Effect of gamma‐irradiation on the electret properties of poly(L‐lactide)

Yovcheva

Marudova

Viraneva

et al. 2012

J of Applied Polymer Sci

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Electret stability of poly(L-lactide) (PLA) films, gamma-irradiated up to 100 kGy has been investigated by measuring the surface potential during the storage period. PLA samples-40-lm thick films-were prepared by the casting method and then irradiated in a 60 Co radiation facility at a dose rate of 0.25 kGy/h. The structural changes during the irradiation were estimated by viscometric, differential scanning calorimetry and scanning electron microscope measurements. Random chain scission and appearance of end radicals are the most probable results of the irradiation process. After irradiation, the samples were charged in a corona discharge system and surface potential was measured by the method of the vibrating electrode with compensation. The values of the surface potential of the irradiated samples were higher in comparison with the non-irradiated samples. This effect could be related to the degradation of the macromolecules and changes in the crystal state of PLA during the irradiation. Both of the mentioned factors lead to structural defects that increase the number of discrete trapping levels. The effect of low pressure on the surface potential drop was also investigated.

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